Selective radiotracers and methods of use

Abstract

The present disclosure relates to radiotracers that selectively bind to voltage-gated sodium channels (e.g., NaV1.7 or NaVl.8) and which are useful for detecting, imaging, and / or quantifying the NaVs, e.g., using positron-emission tomography (PET). The disclosure is also directed to processes for preparing the radiotracers, and to the use of the radiotracers for imaging a tissue or a subject, e.g., in vivo. The disclosure is further related to methods of pain management and improved identification and diagnosis allowing for rapidly identifying the location of or source of pain. The disclosure also relates to growth mediums, cell cultures, and kits.

Description

SELECTIVE RADIOTRACERS AND METHODS OF USERELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 717,543, filed on November 7, 2024, U.S. Provisional Application No. 63 / 749,213, filed on January 24, 2025. and U.S. Provisional Application No. 63 / 814,270, filed on May 30, 2025, the contents of which are each incorporated herein by reference in their entireties.BACKGROUND

[0002] Pain is a widespread health issue throughout the world, but the causes of pain are often misdiagnosed or improperly treated due to a lack of reliable methods for the objective evaluation of pain intensity and alleviation. For example chronic pain, which affects over one quarter of people living in the United States, is typically treated by medications such as opioids that only temporarily mask pain without addressing the root cause, and are associated with serious side-effects or risk of addiction. (See. e.g., Dydyk AM, Chronic Pain. In: StatPearls [Internet], Treasure Island (FL): StatPearls Publishing; 2023 Jan; Rikard SM, et al., MMWRMorb. Mortal Wkly. Rep. (2023);72:379-385; Kritikou P, et al. Clin. Pract. (2023) 27; 13(1): 166-176; each of which are incorporated herein by reference in their entireties).

[0003] Pain often has no detectable anatomical component that correlates with a person's symptoms, and there is a lack of suitable techniques or biomarkers that can reliably identify the source of pain, objectively measure pain intensity, or quantify response to therapy or analgesia. This creates a significant obstacle for physicians diagnosing and treating pain, and also researchers involved in the discovery of new treatments for pain, who are limited to using imprecise and subjective methods for assessing pain in subjects. Consequently, there is a dearth of new pain treatments, and pain is often misdiagnosed and treated by inappropriate or ineffective methods that can prolong suffering.

[0004] Voltage-gated sodium channels (NaVs) encompass a family of transmembrane proteins (Navl.l - Navi.9 and Nax) that conduct sodium currents across membranes in various tissues in response to changes in membrane voltage. Voltage-gated sodium channels contain a pore-forming alpha subunit and a stabilizing beta subunit. Multiple isoforms of the alpha subunit have been identified based on the similarity to amino acid sequences in the extracellular and transmembrane domain. Ion channel subunits are expressed in neurons and can be used for studying chronic pain treatments.

[0005] While NaVs are expressed in tissues throughout the body and are crucial for normal animal function, some NaVs play a central role in the transmission and modulation of pain signals and represent an important pharmacologic target for pain treatment. The isoforms NaV 1.7, NaV1.8, and NaV1.9 are primarily expressed in nen es that are centrally involved in nociceptive signaling, and are known as the neuronal NaVs. There is an abundance of literature detailing NaVs and their role in normal animal function. (See, e.g., (Hameed S. Mol. Pain (2019) 15: 1744806919858801; Dib-Hajj SD. et al. Nat. Rev. Neurosci. (2015) 16(9):511-519; Bennett, D. L , et al. (2019). Physiological Reviews (2019) 99(2): 1079-1151 Kwong et al., Curr. Opin. Pharmacol. (2015), 22:131-139; Bean et al, Nat. Rev. Neurosci.(2007) 8:451-465; Bagal SK, et al. Bioorg. Med. Chem.. Lett. (2014) 24(16):3690-3699; Ratte S, et al. Curr Opin. Neurobiol. (2016) 36:31-37; Alles Sascha R. A., et al. Frontiers in Pain Research (2021) 2:106; Cox JJ, et al. Nature (2006) 444(7121):894-898; Djouhri et al. report TTX-resistant sodium channel Navi.8 (SNS / PN3) expression as correlating with membrane properties in rat nociceptive primary afferent neurons. J. Physiol. (2003) 550, 3:739-752; Barbieri et al. report voltage-gated sodium channel dysfunctions in neurological disorders. Life (2023) 13, 1 19; Hoyt et al. report 3-amino-l,5-benzodiazepinones as potent, statedependent sodium channel blockers with anti-epileptic activity, Bioorg. Med. Chem. Lett. (2008), 18, 1963-1966; Ramdas et al. report NaV 1.7 inhibitors with oral efficacy in pain models. J. Med. Chem. (2020) 63, 6107-6133; Wang et al. report a series of pyridine amides as NaV1.8 inhibitors, Bioorg. Med. Chem. Lett. (2024). 101, 129655; Schoenberger et al. report compounds useful as radiotracers for position emission tomography imaging of voltage gated sodium channels, U.S Patent No. 11,117,858; See also US Patent App. Pub. 2014 / 0213616, WO 2015 / 089361, WO 2018 / 163077, WO 2018 / 213426, WO 2020 / 206119, and WO 2020 / 219867. Each reference cited herein is incorporated by reference in its entirety’. The citation of any reference is not an admission of prior art.

[0006] NaVs have attracted some attention as targets for diagnostic applications. For example, a radiolabeled variant of lidocaine known as radiocaine was developed for use with positron emission tomography (PET) and has been used to image NaVs in vivo. (See U.S. Patent No. 11,117,858). However, radiocaine does not bind selectively to a particular NaV isoform and therefore is not suitable for imaging only neuronal NaVs. Indeed, there is a lack of compounds and techniques for selectively imaging NaV isoforms, particularly the neuronal NaVs.

[0007] As such, there is an unmet need for new compounds and techniques that can be used for detecting or measuring pain, particularly compounds that can be used to selectively image neuronal NaVs.SUMMARY

[0008] The present disclosure relates to certain radiotracers, which are small molecule compounds covalently bonded to a radionuclide that bind to a voltage-gated sodium channel (NaV). In some aspects, the radiotracers can selectively bind to a NaV isoform (e.g., NaV1.7 or NaV1.8). Also disclosed herein are pharmaceutical compositions comprising the radiotracers, and methods of using or making the radiotracers, including diagnostic and analytical methods, e.g., for detecting or measuring pain. Kits and growth mediums are also disclosed.

[0009] It will be understood that the radiotracers disclosed herein have relatively short half-lives and would not be considered for use in therapeutic methods (e.g., the treatment of pain) as a substitute for the radiotracer’s non-radiolabel ed NaV blocking counterpart. However, due to the detectability of the radiotracers with certain imaging techniques (e.g.. PET scanning) and the ability to selectively bind a NaV with the radiotracers, the radiotracers of the present disclosure are particularly useful in analytical and diagnostic methods.

[0010] In particular, the radiotracers of the present disclosure can bind to and / or inhibit NaV (e.g., NaV1.7 or NaV1.8). As such, the present disclosure also relates to methods for detecting, quantifying, or localizing aNaV (e.g.. NaV1.7 or NaV1.8), e.g., in a sample or subject, e.g., in vivo, using the radiotracers with an imaging technique (e.g., PET scanning). Also, because the radiotracers can bind (e.g., selectively bind) to and / or inhibit aNaV (e.g., NaV 1.7 or NaV1.8), the radiotracers can therefore also be used for detecting or quantifying (e.g., selectively detecting or quantifying) a tissue that expresses aNaV, e.g., NaV1.7 or NaV1.8. The radiotracers of the present disclosure can also be used for evaluating the binding of a test compound to aNaV, e.g., NaV1.7 or NaV1.8.

[0011] A radiotracer of the present disclosure can be a compound comprising a structure ofFormula (salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof, wherein: W is C or N; X is CH or N; Y is C or N, optionally, wherein at least one of X and Y is N; R30is hydrogen, (Ci-C4)-alkyl (e.g., methyl or ethyl), (C3-C8)-cycloalkyl (Ci-C4)-haloalkyl (e.g., CF3), optionally substituted heterocyclyl (e.g., morpholinyl), optionally substituted aryl (e.g.. phenyl), optionally substituted heteroaryl (e.g., imidazolyl), or -NH-heterocyclyl; R1is aryl or heteroaryl, wherein the aryl or heteroaryl is optionally substituted with one or more groups selected from the group consisting of a radionuclide, (Ci-C4)-haloalkyl, optionally substituted (Ci-Cs)-alkyl, (C3-Cio)-cycloalkyl, halogen (e.g., F, Cl, or Br, including unstable isotopes thereof such as18F), heteroaryl, cyano, amino, nitro, aryloxyl, aryl, (Ci-C8)-alkyloxyl, (Ci-C4)-haloalkyloxyl, sulfanyl, trifluoromethylsulfanyl, and arylalkoxyl (including, e.g.,18F); R2is selected from the group consisting of aryl, heteroaryl, and heterocyclyl, wherein the aryl, heteroaryl, and heterocyclyl are optionally substituted with one or more groups selected from the group consisting of (Ci-C4)- haloalkyl, optionally substituted (Ci-Cs)-alkyl, (C3-Cio)-cycloalkyl. halogen (e.g., F, Cl, or Br. including isotopes thereof such as18F), heteroaryl, cyano, amino, nitro, aryloxyl, aryl, (Ci-Cs)- alkyloxyl, (Ci-C4)-haloalkyloxyl, oxo, alkylsulfinyl, alkylsulfonyl, alkyliminosulfanonyl, alkylsulfoxide, sulfonamide, alkylsulfoximinyl, morpholinyl, oxazolyl, -S(O)(NH)-(Ci-C4)-alkyl (e.g., -S(O)(NH)-CH3), and -S(O)(NMe)-(Ci-C4)-alkyl; when Y is C, R3is selected from the group consisting of hydrogen, cyano, halogen (e.g., F, Cl, or Br, including isotopes thereof such as18F), (Ci-Cs)-alkyoxyl, (Ci-C4)-haloalkyl (e.g., CFs), (Ci-C4)-haloalkyloxyl, (C3-Cs)- cycloalkyl, nitro, and haloalkyloxyl; or when Y is N, R3is absent; when W is C, R4is selected from the group consisting of hydrogen, cyano, halogen (e.g., F, Cl, or Br. including isotopes thereof such as18F), (Ci-C8)-alkyoxyl. (Ci-C4)-haloalkyl (e.g., CF3), (Ci-C4)-haloalkyloxyl, optionally substituted (Ci-Cs)-alkyl, (C3-C8)-cycloalkyl, and morpholinyl; or when W is N, R4is absent; or R3and R4together form a (C3-C5)-carbocyclic ring (including carbon atoms to which R3and R4are attached); wherein R3and R4are not both hydrogen; and wherein the compound of Formula (A) comprises at least one radionuclide (e.g..18F).

[0012] A radiotracer of the present disclosure can be a compound that comprises a structure ofFormulasalt thereof (e.g., a pharmaceutically acceptablesalt thereof), or a tautomer thereof,, wherein X is a radionuclide (e.g.,18F). In some embodiments, the radionuclide is18F.

[0013] The radiotracer of Formula (I) can be a compound that comprises a structure of Formulasalt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof.

[0014] The radiotracer of Formula (I) or (la) can be a compound that comprises a structure ofFormula (salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof.

[0015] The radiotracer of Formula (I) or (la) can be a compound that comprises a structure ofFormulasalt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof.

[0016] A radiotracer of the present disclosure can be a compound that comprises a structure ofFormulasalt thereof (e.g.. a pharmaceutically acceptable salt thereof), or a tautomer thereof, wherein X is a radionuclide (e.g.,18F). In some embodiments, the radionuclide is18F.

[0017] The radiotracer of Formula (IV) can be a compound that comprises a structure ofFormulasalt thereof (e g., a pharmaceutically acceptable salt thereof), or a tautomer thereof.

[0018] A radiotracer of the present disclosure can be a compound that comprises a structure ofFormulasalt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof, wherein one of Xaand Xbis a radionuclide (e.g.,18F). In some embodiments, one of Xaand Xbis a radionuclide (e.g.,18F) and the other of Xaand Xbis a stable F isotope (i.e.,19F). In some embodiments, the radionuclide is18F. In some embodiments, one of Xaand Xbis18F, and the other of Xaand Xbis19F. In some embodiments, Xais18F, and Xbis19F. In some embodiments, Xais19F and Xbis18F. In some embodiments, each of Xaand Xbis independently18F.

[0019] The radiotracer of Formula (II) can be a compound that comprises a structure of Formulasalt thereof (e.g.. a pharmaceutically acceptable salt thereof), or a tautomer thereof, wherein one of Xaand Xbis a radionuclide (e.g.,18F). In some embodiments, one of Xaand Xbis a radionuclide (e.g.,18F) and the other of Xaand Xbis a stable F isotope (i.e.,19F). In some embodiments, the radionuclide is18F. In some embodiments, one of Xaand Xbis18F, and the other of Xaand Xbis19F. In some embodiments, Xais18F, and Xbis19F. In some embodiments, Xais19F and Xbis18F. In some embodiments, each of Xaand Xbis independently18F.

[0020] The radiotracer of Formula (II) or (Ila) can be a compound that comprises a structure ofsalt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof.

[0021] The radiotracer of Formula (II) or (Ila) can be a compound that comprises a structure ofFormulasalt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof.

[0022] A radiotracer of the present disclosure can be a compound that comprises a structure ofFormulasalt thereof (e.g., a pharmaceuticallyacceptable salt thereof), or a tautomer thereof, wherein X is a radionuclide (e.g.,18F). In some embodiments, the radionuclide is18F.

[0023] The radiotracer of Formula (III) can be a compound comprising a structure of Formula(Illa):(Illa), or a salt thereof (e.g. a pharmaceutically acceptable salt thereof), or a tautomer thereof.

[0024] A radiotracer of the present disclosure can be a compound comprising a structure ofFormulasalt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof, wherein: W is C or N; X is CH or N; Y is C or N; R30is hydrogen, (Ci-C4)-alkyl (e.g., methyl or ethyl), (C3-Cs)-cycloalkyl (Ci-C4)-haloalkyl (e.g., CF3), optionally substituted heterocyclyl (e.g., morpholinyl), optionally substituted aryl (e.g., phenyl), optionally substituted heteroaryl (e.g.. imidazolyl), or -NH-heterocyclyl; R1is aryl or heteroaryl, wherein the ar l or heteroaryl is optionally substituted with one or more groups selected from the group consisting of a radionuclide, (Ci-C4)-haloalkyl, optionally substituted (Ci-Cs)-alkyl, (Cs- Cio)-cycloalkyl, halogen (e.g., F, Cl, or Br, including isotopes thereof such as18F), heteroaryl, cyano, amino, nitro, aryloxyl, aryl, (Ci-Cs)-alkyloxyl. (Ci-C4)-haloalkyloxyl. sulfanyl, trifluoromethylsulfanyl, and arylalkoxyl (including, e.g.,18F); R2is selected from the group consisting of aryl, heteroaryl, and heterocyclyl, wherein the aryl, heteroaryl, and heterocyclyl are optionally substituted with one or more groups selected from the group consisting of (C1-C4)- haloalkyl, optionally substituted (Ci-Cs)-alkyl, (C3-Cio)-cycloalkyl. halogen (e.g., F, Cl, or Br, including isotopes thereof such as18F), heteroaryl, cyano, amino, nitro, aryloxyl. aryl, (Ci-Cs)- alkyloxyl, (Ci-C4)-haloalkyloxyl, oxo, alkylsulfinyl, alkylsulfonyl, alkyliminosulfanonyl, alkylsulfoxide, sulfonamide, alkylsulfoximinyl, morpholinyl, oxazolyl, -S(O)(NH)-(Ci-C4)-alkyl (e.g., -S(O)(NH)-CH3), and -S(O)(NMe)-(Ci-C4)-alkyl; when Y is C, R3is selected from the group consisting of hydrogen, cyano, halogen (e.g., F, Cl. or Br, including isotopes thereof such as18F), (Ci-C8)-alkyoxyL (Ci-C4)-haloalkyl (e.g., CF3), (Ci-C4)-haloalkyloxyl, (Cs-Cs)- cycloalkyl, nitro, haloalkyloxyl; or when Y is N, R3is absent; when W is C, R4is selected fromthe group consisting of hydrogen, cyano, halogen (e.g., F, Cl, or Br, including isotopes thereof such as18F), (Ci-C8)-alkyoxyl, (Ci-C4)-haloalkyl (e.g., CF3), (Ci-C-O-haloalkyloxyl, optionally substituted (Ci-C8)-alkyl, (C3-C8)-cycloalkyl, and morpholinyl; or when W is N, R4is absent: or R3and R4together form a (C3-Cs)-carbocyclic ring (including carbon atoms to which R3and R4are attached); optionally, wherein R3and R4are not both hydrogen; wherein the compound comprises at least one radionuclide (e.g.,18F); and with the proviso that, when X is CH and W and Y are each C, then R1is not 4-fluoro-2-methylphenyl and R2is not a methoxymethylsubstituted pyridinone or a hydroxy-substituted pyridine.

[0025] A radiotracer of the present disclosure can be a compound that comprises a structure provided in Table 1 disclosed herein, or a pharmaceutically acceptable salt thereof.

[0026] A radiotracer of the present disclosure can be a radionuclide-containing variant of LTGO- 33, LTGO-34, LTGO-OOl, LTGO-305, suzetrigine, or PF-05089771, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof. In some embodiments, a radiotracer of the present disclosure is a radionuclide-containing variant of LTGO-33, LTGO-34, suzetrigine, or PF-05089771. In some embodiments, a radiotracer of the present disclosure is a radionuclide-containing variant of LTGO-33. In some embodiments, a radiotracer of the present disclosure is a radionuclide-containing variant of LTGO-34. In some embodiments, a radiotracer of the present disclosure is a radionuclide-containing variant of LTGO-OOL In some embodiments, a radiotracer of the present disclosure is a radionuclide-containing variant of LTGO-305. In some embodiments, a radiotracer of the present disclosure is a radionuclidecontaining variant of suzetrigine. In some embodiments, a radiotracer of the present disclosure is a radionuclide-containing variant of PF-05089771. In some embodiments, the radionuclide is18F. It will be understood that the variant can comprise the same carbon skeleton of LTGO-33, LTGO-34, LTGO-OOl, LTGO-305, suzetrigine. or PF-05089771. with the only variation being the substitution of a single atom (e.g., a19F fluorine atom) for a radionuclide (e.g., an18F fluorine atom). It will be understood that the variant can comprise the same carbon skeleton as LTGO- 33, LTGO-34, suzetrigine, or PF-05089771, with the only variation being the substitution of a single atom (e.g., a19F fluorine atom) for a radionuclide (e.g., an18F fluorine atom).

[0027] A radiotracer of the present disclosure can be an18F-containing variant of LTGO-33, LTGO-34, LTGO-OOl, LTGO-305, suzetrigine, or PF-05089771. In some embodiments, a radiotracer of the present disclosure is an18F-containing variant of LTGO-33, LTGO-34, suzetrigine, or PF-05089771. In some embodiments, a radiotracer of the present disclosure is an18F-containing variant of LTGO-33. In some embodiments, a radiotracer of the present disclosure is an18F-containing variant of LTGO-34. In some embodiments, a radiotracer of thepresent disclosure is an18F-containing variant of LTGO-OOl. In some embodiments, a radiotracer of the present disclosure is an18F-containing variant of LTGO-305. In some embodiments, a radiotracer of the present disclosure is an18F-containing variant of suzetrigine. In some embodiments, a radiotracer of the present disclosure is an18F-containing variant of PF- 05089771. It will be understood that the variant can comprise the same carbon skeleton as LTGO-33, LTGO-34, LTGO-OOl, LTGO-305, suzetrigine, or PF-05089771, with the only variation being the substitution of a19F fluorine atom for an18F fluorine atom. It will be understood that the variant can comprise the same carbon skeleton as LTGO-33, LTGO-34, suzetrigine, or PF-05089771, with the only variation being the substitution of a19F fluorine atom for an18F fluorine atom.

[0028] A radiotracer of the present disclosure can be a compound that comprises a structure ofFormula (salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof, wherein X is a radionuclide (e.g.,18F). It will be understood that the compound can exist in its tautomeric form:

[0029] A radiotracer of the present disclosure can be Compound C:(Compound C; 2-(4-(fluoro-18F)-2-methylphenoxy)-N-(2- hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide), or a salt thereof (e.g., a pharmaceuticallyacceptable salt thereof), or a tautomer thereof. It will be understood that Compound C can exist

[0030] A radiotracer of the present disclosure can be Compound (B):(Compound B; 2-(4-(fluoro-18F)-2-methylphenoxy)-N-(l-(methoxymethyl)-2-oxo-l ,2-dihydropyridin-4-yl)-4- (trifluoromethyl)benzamide) or a salt thereof (e.g. , a pharmaceutically acceptable salt thereof), or a tautomer thereof.

[0031] A radiotracer of the present disclosure can comprise a specific activity' of about 0.2 Ci / pmol or greater, e.g., about 0.4 Ci / pmol, about 0.6 Ci / pmol, about 0.8 Ci / pmol, about 1.0 Ci / pmol, about 1.2 Ci / pmol, about 1.4 Ci / pmol, about 1.6 Ci / pmol, about 1.8 Ci / pmol, about 2.0Ci / pmol, about 2.2 Ci / pmol, about 2.4 Ci / pmol, about 2.6 Ci / pmol, about 2.8 Ci / pmol, about 3.0Ci / pmol, about 3.5 Ci / pmol, about 4.0 Ci / pmol, about 4.5 Ci / pmol, about 5.0 Ci / pmol, about 6.0Ci / pmol, about 7.0 Ci / pmol, about 8.0 Ci / pmol, about 9.0 Ci / pmol, about 10 Ci / pmol, about 12Ci / pmol, about 14 Ci / pmol, about 16 Ci / pmol, about 18 Ci / pmol, about 20 Ci / pmol, or greater.

[0032] In some aspects, this disclosure relates to tracer compounds 2-(4-(fluoro-18F)-2- methylphenoxy)-N-(l-(methoxymethyl)-2-oxo-l,2-dihydropyridin-4-yl)-4-(trifluoromethy l)benzamide (Compound B) and 2-(4-(fluoro-18F)-2-methylphenoxy)-N-(2- hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide (Compound C), derivatives, or salts thereof, and uses as a PET imaging agent. In certain embodiments, this disclosure relates to precursor compounds for generating tracer compounds 2-(4-(fluoro-18F)-2-methylphenoxy)-N-(l- (methoxymethyl)-2-oxo-l,2-dihydropyridin-4-yl)-4-(trifluoromethyl)benzamide (Compound B) and 2-(4-(fluoro-18F)-2-methylphenoxy)-N-(2-hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide (Compound C) such as N-(l-(methoxymethyl)-2-oxo-l,2-dihydropyridin-4-yl)-2-(2-methyl-4-(4,4,5,5-tetramethyl-l,3,2-dioxaborolan-2-yl)phenoxy)-4-(trifluoromethyl)benzamide (Compound A), derivatives, or salts thereof

[0033] The present disclosure further relates to pharmaceutical compositions comprising a radiotracer disclosed herein, and optionally one or more pharmaceutically acceptable excipients. In some embodiments, the one or more pharmaceutically acceptable excipients comprise water, ethanol, or a combination thereof. In some embodiments, the pharmaceutical composition has a pH of between about 5 and about 8.

[0034] A pharmaceutical composition of the present disclosure can have a radiochemical purity of between about 20% and about 100%, e.g., between about 30% and about 100%, between about 40% and about 100%, between about 50% and about 100%, between about 60% and about 100%, between about 70% and about 100%, between about 80% and about 100%, between about 90% and about 100%, between about 95% and about 100%, or between about 98% and about 100%.

[0035] The present disclosure also relates to methods comprising administering a radiotracer or a pharmaceutical composition disclosed herein, e.g., to a subject or a sample.

[0036] A method of the present disclosure can be for imaging a subject or sample, comprising administering to a subject or sample a radiotracer disclosed herein, or a pharmaceutical composition disclosed herein, and performing an imaging technique disclosed herein (e.g., positron emission tomography (PET)) on the subject or sample. The method can comprise imaging a cell, tissue, organ, or a combination thereof, in the subject or in the sample.

[0037] The method can comprise imaging a voltage-gated sodium channel (NaV), e.g., selectively imaging NaV1.7 or NaV1.8.

[0038] The radiotracer or pharmaceutical composition can be administered to the sample or subject about 4 hours (e.g., about 3 hours, about 2 hours, or less) prior to performing the imaging technique (e.g., PET) on the subject or sample.

[0039] The present disclosure further relates to methods involving the administration of a radiotracer or a pharmaceutical composition disclosed herein. The method can comprise selectively binding NaV 1.7 with the radiotracer, and optionally, detecting, quantifying, or localizing the radiotracer after it has selectively bound to NaV1.7.

[0040] The method can comprise selectively binding NaV1.8 with the radiotracer, and optionally, detecting, quantifying, or localizing the radiotracer after it has selectively bound to NaV 1.8.

[0041] In some aspects, the present disclosure relates to a method for the detection of a voltagegated sodium channel (NaV), comprising administering (e.g., intravenously) to a subject or asample a radiotracer of the present disclosure, or a pharmaceutical composition of the present disclosure. The radiotracer or the pharmaceutical composition can be administered to the sample or subject within eight hours (e.g., four hours, or within four hours, e.g., about 3 hours, about 2 hours, or less) of performing an imaging technique for detecting the radiotracer, e.g., a positron emission tomography (PET) scan. In some embodiments, the method comprises selectively binding NaV1.7 with the radiotracer, and optionally, detecting, quantifying, or localizing the radiotracer after it has selectively bound to NaV1.7. In some embodiments, the method comprises selectively binding NaV1.8 with the radiotracer, and optionally, detecting, quantifying, or localizing the radiotracer after it has selectively bound to NaV1.8. In some embodiments, the method comprises subjecting the subject or sample to a PET scan, and optionally, detecting, quantifying, or localizing NaV1.7 in the subject. In some embodiments, the method comprises subjecting the subject or sample to a PET scan, and optionally, detecting, quantifying, or localizing NaV1.8 in the subject.

[0042] In some aspects, the present disclosure relates to a method for the detection of aNaV (e.g., NaV1.7 or NaV1.8) in a subject, comprising administering (e.g., intravenously) to a subject (e.g., a mammal) a radiotracer of the present disclosure, or a pharmaceutical composition of the present disclosure. In some embodiments, the method further comprises a step of performing an imaging technique on the subject, such as a PET scan. In some embodiments, the radiotracer is administered to the subject about 15 to about 120 minutes prior to performing the imaging technique, e.g.. prior to the PET scan.

[0043] In a method of the present disclosure, the radiotracer or pharmaceutical composition can administered to the subject parenterally, e.g., intravenously, subcutaneously, intramuscularly, intradermally, intrathecally, intra-articularly, or intra-arterially. In a method of the present disclosure, the radiotracer or pharmaceutical composition can be administered intravenously. In a method of the present disclosure, the radiotracer can be administered to a subject intravenously.

[0044] In a method of the present disclosure the radiotracer can be administered (e.g., intravenously, e.g.. to a human) in an amount sufficient to provide a radioactivity of about 3 mCi (108 MBq) to about 10 mCi (370 MBq).

[0045] In some aspects, the present disclosure relates to a method for evaluating the binding of a test compound to a NaV (e.g., NaV1.7 or NaV1.8) in a sample or in a subject, comprising coadministering a radiotracer of the present disclosure, or a pharmaceutical composition of the present disclosure, and the test compound, to the sample or subject. The radiotracer (or pharmaceutical composition), the test compound, or both can be administered intravenously. Insome embodiments, the radiotracer (or pharmaceutical composition) and the test compound are administered within a short period of time of each other (e.g.. within 10 minutes, within 5 minutes, within 2 minutes, within 1 minute) or are administered simultaneously. In some embodiments, the radiotracer or pharmaceutical composition, and the test compound are each administered within a period of about 1 hour (e.g., w ithin 30 minutes, within 10 minutes, within 5 minutes, within 2 minutes, within 1 minute) or are administered simultaneously.

[0046] In some embodiments, the test compound is a non-radioactive NaV inhibitor (e.g., a nonradioactive NaV 1.7 inhibitor or a non-radioactive NaV 1.8 inhibitor). In some embodiments, the test compound is a non-radiolabeled NaV binder (e.g., a non-radiolabeled NaV 1.7 binder or a non-radiolabeled NaV 1.8 binder).

[0047] In some embodiments, the test compound is administered orally to the subject. In some embodiments, the test compound is administered parenterally to the subject. In some embodiments, the radiotracer, or the pharmaceutical composition, and / or the test compound, are administered intravenously.

[0048] In some embodiments the method further comprises a step of imaging the subject or sample with an imaging technique, e.g., a PET scan. In some embodiments, the method further comprises detecting and / or quantitating the radiotracer in the sample or in the subject, and optionally, evaluating binding of the test compound to a NaV (e.g., NaV1.7 or NaV1.8).

[0049] The unstable radionuclide of a radiotracer disclosed herein results in certain emissions. For example, fluorine- 18 (18F) decays predominantly by [3 emission. The emissions from a radionuclide or radiotracer of the present disclosure can be detected using an imaging technique disclosed herein, e.g., by PET. As such, a method of the present disclosure can comprise a step of detecting emissions. The method can also comprise creating an image indicating or highlighting a location of a compound (e.g., radiotracer) isotopically enriched with a radionuclide (e.g., fluorine-18) in a subject. The method can further comprise a step of quantifying the emission. The method can also comprise providing an emission quantity. The method can further comprise recording the emission quantity, such as on non-transitory computer readable media. The method can also comprise correlating the emission quantity to a concentration of the radiotracer in an area of the subject. The method can also compnse reporting the emission quantify to a medical professional.

[0050] A method of the present disclosure can comprise: (a) administering a radiotracer of the present disclosure to a subject; and (b) scanning the subject for emissions from an area of the subject. The scanning can comprise PET scanning. The emissions can be from the interior or exterior of a nerve in the subject. The nerve can comprise a voltage-gated sodium channel(NaV), e.g., NaV 1.8. The radiotracer can be a compound of Formula (A), Formula (B), Formula (I) (e.g., a compound of Formula (la), (la-1), or (la-2)), Formula (II) (e.g., a compound of Formula (e.g., a compound of Formula (Ila), (IIa-1), or (IIa-2)), Formula (III) (e.g., a compound of Formula (Illa)), Formula (IV) (e.g., a compound of Formula (IV a)), Formula (A1)-(A57), a compound of Table 1), or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof.

[0051] A method of the present disclosure can comprise: (a) administering a composition comprising 2-(4-(fluoro- 18F)-2-methy lphenoxy)-N-(2-hydroxypyridin-4-yl)-4- (trifluoromethyl)benzamide (Compound C) or salt thereof (e.g., a pharmaceutically acceptable salt thereof) or a tautomer thereof, isotopically enriched with fluorine- 18, to a subject; and (b) scanning the subject for emissions from an area of the subject. The scanning can comprise PET scanning. The emissions can be from the interior or exterior of a nen e in the subject. The nerve can comprise a voltage-gated sodium channel (NaV), e.g., NaV 1.8. The method can further comprise a step of detecting the emissions and creating an image indicating or highlighting the location of the compound (e.g., Compound C) isotopically enriched with fluorine-18 in the subject. The method can further comprise a step of quantifying the emission, providing an emission quantity, and recording the emission quantity on non-transitory computer readable media. The method can further comprise correlating the emission quantity to a concentration of the radiotracer (e.g., Compound C) in an area of the subject. The method can also comprise reporting the emission quantity to a medical professional.

[0052] In certain embodiments, this disclosure relates to methods comprising: a) administering a composition comprising a radiotracer of the present disclosure to a subject; and scanning the subject for emissions from an area of the subject. In certain embodiments, the radiotracer binds to or enters cells, tissues, or organs that express a voltage-gated sodium channel. In certain embodiments, the emissions are from or on the exterior or inside a nerve. The radiotracer can be a compound of Formula (A), Formula (B), Formula (I) (e.g., a compound of Formula (la), (la-1), or (la-2)), Formula (II) (e.g., a compound of Formula (e.g., a compound of Formula (Ila), (IIa-1 ), or (IIa-2)), Formula (III) (e.g., a compound of Formula (Illa)). Formula (IV) (e.g., a compound of Formula (IVa)), Formula (A1)-(A57), a compound of Table 1, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof.

[0053] In certain embodiments, this disclosure relates to methods comprising: a) administering a composition comprising the tracer compound 2-(4-(fluoro-18F)-2- methylphenoxy)-N-( 1 -(methoxymethyl)-2-oxo- 1 ,2-dihydropyridin-4-yl)-4-(trifluoromethyl)benzamide (Compound B) and / or 2-(4-(fluoro-18F)-2 -methylphenoxy )-N- (2-hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide (Compound C) isotopically enriched with fluorine 18 to a subject; and scanning the subject for emissions from an area of the subject. In certain embodiments, the tracer 2-(4-(fluoro-18F)-2-methylphenoxy)-N-(l- (methoxymethyl)-2-oxo- 1 ,2-dihy dropyridin-4-yl)-4-(trifluoromethyl)benzamide (C ompound B) and / or 2-(4-(fluoro- 18F)-2 -methylphenoxy )-N-(2-hy droxypyri din-4-yl)-4- (trifluoromethyl) benzamide (Compound C) binds to or enters cells, tissues, or organs that express a voltage-gated sodium channel. In certain embodiments, the emissions are from or on the exterior or inside a nerve.

[0054] In certain embodiments, the radiotracer is administered at a dose of 0.04 to 0.9 pmol / kg or 0.04 to 10 mol / kg. e.g., intravenously, e.g., to a human subject. In certain embodiments, scanning the subject for emissions is for between 15 and 30 minutes, or longer. In certain embodiments, administering is at a dose of about 0.9 pmol / kg and scanning the subject (e.g., human subject) for emissions is for 15 minutes or longer. The radiotracer can be a compound of Formula (A), Formula (B), Formula (I) (e.g., a compound of Formula (la), (la-1), or (la-2)), Formula (II) (e.g., a compound of Formula (e.g., a compound of Formula (Ila), (IIa-1), or (IIa-2)), Formula (III) (e.g., a compound of Formula (Illa)), Formula (IV) (e.g., a compound of Formula (IV a)), Formula (A1)-(A57), a compound of Table 1, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof, or a tautomer thereof.

[0055] In certain embodiments, the tracer 2-(4-(fluoro-18F)-2-methylphenoxy)-N-(l- (methoxymethyl)-2-oxo- 1 ,2-dihy dropyridin-4-yl)-4-(trifluoromethyl)benzamide (C ompound B) and / or 2-(4-(fluoro-18F)-2 -methylphenoxy )-N-(2-hy droxypyri din-4-yl)-4- (trifluoromethyl) benzamide (Compound C) is administered at a dose of 0.04 to 0.9 pmol / kg or 0.04 to 10 pmol / kg. In certain embodiments, scanning the subject for emissions is for between 15 and 30 min or longer. In certain embodiments, administering is at a dose of about 0.9 pmol / kg and scanning the subject for emissions is for 15 min or more.

[0056] In certain embodiments, methods further comprise the step of detecting and / or measuring the emissions and creating an image indicating or highlighting the location of the radiotracer in the subject. In certain embodiments, the emissions are from or on the exterior or inside a nerve. The radiotracer can be a compound of Formula (A), Formula (B), Formula (I) (e g., a compound of Formula (la), (la-1), or (la-2)), Formula (II) (e.g., a compound of Formula (e.g., a compound of Formula (Ila), (Ila- 1), or (IIa-2)), Formula (III) (e.g., a compound of Formula (Illa)), Formula (IV) (e.g., a compound of Formula (IV a)), Formula(A1)-(A57), a compound of Table 1, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof.

[0057] In certain embodiments, methods further comprise the step of detecting and / or measuring the emissions and creating an image indicating or highlighting the location of the compound 2-(4-(fluoro- 18F)-2-methylphenoxy )-N-( 1 -(methoxy methyl)-2-oxo- 1,2- dihydropyridin-4-yl)-4-(trifluoromethyl)benzamide (Compound B) and / or 2-(4-(fluoro-18F)- 2-methylphenoxy)-N-(2-hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide (Compound C) isotopically enriched with fluorine 18 in the subject. In certain embodiments, the emissions are from or on the exterior or inside a nerve.

[0058] In certain embodiments, methods comprise the step of detecting, measuring, and / or quantifying the emission providing an emission quantity and optionally correlating the emission measurement / detection / quantity to a concentration of radiotracer on or in the cells, tissue, or organ. The radiotracer can be a compound of Formula (A), Formula (B), Formula (I) (e.g., a compound of Formula (la), (la-1 ), or (la-2)), Formula (II) (e.g., a compound of Formula (e.g., a compound of Formula (Ila), (Ila- 1), or (IIa-2)). Formula (III) (e.g., a compound of Formula (Illa)), Formula (IV) (e.g., a compound of Formula (IV a)), Formula (A1)-(A57), a compound of Table 1, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof.

[0059] In certain embodiments, methods comprise the step of detecting, measuring, and / or quantifying the emission providing an emission quantity and optionally correlating the emission measurement / detection / quantity to a concentration of 2-(4-(fluoro-18F)-2- methylphenoxy)-N-(l -(methoxymethyl)-2-oxo- 1 ,2-dihydropyridin-4-yl)-4- (trifluoromethyl)benzamide (Compound B) and / or 2-(4-(fluoro-18F)-2 -methylphenoxy )-N- (2-hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide (Compound C) on or in the cells, tissue, or organ.

[0060] In certain embodiments, methods further comprise the step of correlating a low, high, or abnormal measurement, quantity7, or concentration of a radiotracer disclosed herein to the existence of or diagnosis of a subject at risk of a pain, epilepsy, seizure, movement disorder, central nervous system disease, or condition. In certain embodiments, the disease is pain sensitivity or pain insensitivity, or a neurodegenerative disease. The radiotracer can be a compound of Formula (A), Formula (B), Formula (I) (e.g., a compound of Formula (la), (la- 1), or (la-2)), Formula (II) (e.g., a compound of Formula (e.g., a compound of Formula (Ila). (IIa-1). or (IIa-2)), Formula (III) (e.g.. a compound of Formula (Illa)), Formula (IV) (e.g., acompound of Formula (IV a)), Formula (A1)-(A57), a compound of Table 1, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof.

[0061] In certain embodiments, methods further comprise the step of correlating a low, high, or abnormal measurement, quantity, or concentration of 2-(4-(fluoro-18F)-2- methylphenoxy)-N-(l-(methoxymethyl)-2-oxo-l,2-dihydropyridin-4-yl)-4- (trifluoromethyl)benzamide (Compound B) and / or 2-(4-(fluoro- 18F)-2 -methylphenoxy )-N- (2-hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide (Compound C) to the existence of or diagnosis of a subject at risk of a pain, epilepsy, seizure, movement disorder, central nervous system disease, or condition. In certain embodiments, the disease is pain sensitivity or pain insensitivity, or a neurodegenerative disease.

[0062] A method of the present disclosure can exclude treating a disease or disorder, such as a disease or disorder disclosed herein. For example, the method does not comprise treating a disease or disorder in the subject, e.g., the radiotracer or pharmaceutical composition is administered to the subject in an amount that provides less than a therapeutically effective amount.

[0063] A method of the present disclosure can exclude treating pain or providing analgesia to a subject. For example, the method does not comprise treating pain or providing analgesia to a subject, e.g., wherein the radiotracer or pharmaceutical composition is administered to the subject in an amount that is less than an amount effective to treat pain or provide analgesia to the subject.

[0064] In some embodiments, a radiotracer of the present disclosure is not for treating a disease or disorder.

[0065] In some embodiments, a radiotracer of the present disclosure is not for treating pain or providing analgesia to a subject.

[0066] The present disclosure also relates to a method of manufacturing a radiotracer of the present disclosure, or a pharmaceutical composition of the present disclosure. In some embodiments, a radionuclide (e.g.,18F) or a precursor comprising a radionuclide (e.g.,18F) is introduced in a late stage of synthesis (e.g., as the penultimate or the final synthetic step) to provide the radiotracer. For example, a radionuclide (e.g.,18F) or a precursor comprising the radionuclide can be introduced in a late stage of the manufacture (e.g., as a penultimate or final step in a synthesis of the radiotracer). The method of manufacturing a radiotracer can further comprise a step of purifying the radiotracer, e.g., by filtration.

[0067] In some aspects, the present disclosure relates to a precursor compound useful for manufacturing a radiotracer of the present disclosure, e.g., a precursor disclosed herein.

[0068] The present disclosure further relates to Compound (A):(Compound A; N-(l -(methoxy methyl)-2-oxo- 1,2- dihydropyridin-4-yl)-2-(2-methyl-4-(4,4,5,5-tetramethyl-l,3,2-dioxaborolan-2-yl)phenoxy)- 4-(trifluoromethyl)benzamide), or a salt thereof (e.g. .a pharmaceutically acceptable salt thereof), or a tautomer thereof. In some embodiments, Compound A is a precursor compound useful for manufacturing a radiotracer of the present disclosure. It will be understood that Compound A is a specific compound, and is not the same as generic Formula (A) disclosed herein.

[0069] The present disclosure further relates to Compound (B):(Compound B; 2-(4-(fluoro-18F)-2-methylphenoxy)-N-(l-(methoxymethyl)-2-oxo-l,2-dihydropyridin-4-yl)-4- (trifluoromethyl)benzamide) or a salt thereof (e.g. ,a pharmaceutically acceptable salt thereof), or a tautomer thereof. In some embodiments, Compound B is a precursor compound useful for manufacturing a radiotracer of the present disclosure. It will be understood that Compound B is a specific compound, and is not the same as generic Formula (B) disclosed herein.

[0070] In certain embodiments, this disclosure relates to a PET imaging precursor compound 2-(4-(fluoro-I8F)-2-methylphenoxy)-N-(l-(methoxymethyl)-2-oxo-l,2-dihydropyridin-4-yl)- 4-(trifluoromethyl)benzamide (Compound B) and / or 2-(4-(fluoro-18F)-2-methylphenoxy)-N- (2-hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide (Compound C), derivative, or salt thereof.

[0071] A method of making a compound (e g., radiotracer) disclosed herein can comprise contacting a precursor (e.g., a precursor disclosed herein) with a copper complex and afluorine-18 (18F) ion, e.g., an isotopically enriched fluorine-18 negative ion. The method can further comprise contacting the resulting compound with an acid, e.g., to provide a radiotracer. The radiotracer can be a compound of Formula (A), Formula (B), Formula (I) (e.g., a compound of Formula (la), (la-1), or (la-2)), Formula (II) (e.g., a compound of Formula (e g., a compound of Formula (Ila), (Ila- 1), or (IIa-2)), Formula (III) (e.g., a compound of Formula (Illa)), Formula (IV) (e.g., a compound of Formula (IV a)), Formula (A1)-(A57), a compound of Table 1. or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof.

[0072] For example, a method of the present disclosure can comprise: (a) contacting N-(l- (methoxymethyl)-2-oxo-l,2-dihydropyridin-4-yl)-2-(2-methyl-4-(4,4,5,5-tetramethyl-l,3,2- dioxaborolan-2-yl)phenoxy)-4-(trifluoromethyl)benzamide (Compound A) with a copper complex and an isotopically enriched fluorine-18 negative ion, producing 2-(4-(fluoro-18F)- 2-methylphenoxy)-N-(l-(methoxymethyl)-2-oxo-l,2-dihydropyridin-4-yl)-4- (trifluoromethyl)benzamide (Compound B); and (b) contacting Compound B with an acid, providing 2-(4-(fluoro-18F)-2-methylphenoxy)-N-(2-hydroxypyridin-4-yl)-4- (trifluoromethyl) benzamide (Compound C).

[0073] In certain embodiments, this disclosure relates to methods of making the tracer 2-(4- (fluoro- 18F)-2-methylphenoxy)-N-( 1 -(methoxy methyl)-2-oxo- 1 ,2-dihy dropyridin-4-yl)-4- (trifluoromethyl)benzamide (Compound B) and / or 2-(4-(fluoro- 18F)-2 -methylphenoxy )-N- (2-hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide (Compound C) comprising contacting a precursor compound N-(l -(methoxy methyl)-2-oxo-l ,2-dihydropyridin-4-yl)-2- (2-methyl-4-(4,4,5,5-tetramethyl-l,3,2-dioxaborolan-2-yl)phenoxy)-4- (trifluoromethyl)benzamide (Compound A), derivatives, or salt thereof or salts thereof, with an isotopically enriched fluorine 18 negative ion under conditions producing the PET imaging tracer.

[0074] In certain embodiments, methods include conditions of contacting a precursor compound with a copper complex, e.g., tetrakis(pyridine)copper(II) triflate or other copper Inflate. In certain embodiments, the conditions include a precursor compound with a copper complex and contacting with tetraethylammonium bromide (TEAB), or other a quaternary ammonium compound. In certain embodiments, the conditions include contacting with a solvent such as N,N-Dimethylacetamide (DMA) or a longer alkyl chain acetamide, and / or butyl alcohol or other long chain hydroxy alkyl. In certain embodiments, the conditions include contacting with a solvent such as N.N-Dimethylacetamide (DMA) or a longer alkylchain acetamide, and butyl alcohol or other long chain hydroxy alkyl in a ratio of about 2: 1 or between 3: 1 to 1 : 1.

[0075] In certain embodiments, the enriched fluorine 18 negative ion is a fluorine 18 potassium salt bound to a cryptand. Any suitable cryptand can be used, e.g., a cryptand disclosed herein.

[0076] The present disclosure further relates to kits. A kit of the present disclosure can comprise any compound, precursor, or radiotracer, disclosed herein or a combination thereof. The radiotracer can be a compound of Formula (A), Formula (B), Formula (I) (e.g., a compound of Formula (la), (la-1), or (la-2)), Formula (II) (e.g., a compound of Formula (e.g., a compound of Formula (Ila), (IIa-1), or (IIa-2)), Formula (III) (e.g., a compound of Formula (Illa)), Formula (IV) (e.g.. a compound of Formula (IV a)), Formula (A1)-(A57), a compound of Table 1, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof.

[0077] A kit of the present disclosure can comprise Compound A or Compound B. The kit can further comprise a starting material or substance for preparing a compound (e.g.. radiotracer or precursor).

[0078] A kit of the present disclosure can further comprise instructions for use.

[0079] A kit of the present disclosure can further comprise water, H218O, and / or ethanol. The water, H218O, and / or ethanol can be contained by a container in the kit. The container can be sealed from the atmosphere.

[0080] A kit of the present disclosure can comprise a solid support or filter (e g., a filter for purifying a compound, precursor, or radiotracer of the present disclosure.

[0081] A kit of the present disclosure can comprise potassium. The potassium can be bound to a cryptand. Any suitable cryptand can be used, e.g., a cryptand disclosed herein.

[0082] In certain embodiments, this disclosure relates to kits comprising a precursor PET imaging compound disclosed herein and potassium ion bound to a cryptand.

[0083] In certain embodiments, this disclosure relates to a radiotracer of the present disclosure attached to a solid surface or in or on an array or wells or zones. The radiotracer can be a compound of Formula (A), Formula (B), Formula (I) (e.g., a compound of Formula (la), (la-1), or (la-2)). Formula (II) (e g., a compound of Formula (e.g., a compound of Formula (Ila), (IIa-1), or (IIa-2)), Formula (III) (e.g., a compound of Formula (Illa)), Formula (IV) (e.g., a compound of Formula (IV a)), Formula (A1)-(A57), a compound of Table 1, or a salt thereof (e.g.. a pharmaceutically acceptable salt thereol), or a tautomer thereof.

[0084] In certain embodiments, this disclosure relates to a tracer 2-(4-(fluoro-18F)-2- methylphenoxy)-N-( 1 -(methoxymethyl)-2-oxo- 1 ,2-dihy dropyridin-4-yl)-4-(trifluoromethy 1) benzamide (Compound B) and / or 2-(4-(fluoro-18F)-2-methylphenoxy)-N-(2-hydroxypyridin- 4-yl)-4-(trifluoromethyl) benzamide (Compound C) attached to a solid surface or in or on an array or wells or zones.

[0085] Also disclosed herein are growth mediums. A growth medium of the present disclosure can comprise a radiotracer disclosed herein. The radiotracer can be a compound of Formula (A), Formula (B), Formula (I) (e.g., a compound of Formula (la), (la-1), or (la-2)), Formula (II) (e.g., a compound of Formula (e.g., a compound of Formula (Ila), (IIa-1), or (IIa-2)), Formula (III) (e g., a compound of Formula (Illa)), Formula (IV) (e.g., a compound of Formula (IVa)). Formula (A1)-(A57), a compound of Table 1, or a salt thereof (e.g.. a pharmaceutically acceptable salt thereof), or a tautomer thereof.

[0086] In some aspects the present disclosure relates to a growth medium comprising a compound of Formula (A), Formula (B), Formula (I) (e g., a compound of Formula (la), (la- 1), or (la-2)). Formula (II) (e.g., a compound of Formula (e.g., a compound of Formula (Ila), (IIa-1), or (IIa-2)), Formula (III) (e.g., a compound of Formula (Illa)), Formula (IV) (e.g., a compound of Formula (IVa)), Formula (A1)-(A57), a compound of Table 1, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof. .

[0087] In some aspects the present disclosure relates to a growth medium comprising 2-(4- (fluoro- 18F)-2-methylphenoxy)-N-(2-hy droxypyridin-4-yl)-4-(trifluoromethyl) benzamide (Compound C) or salt thereof (e g., a pharmaceutically acceptable salt thereof), or a tautomer thereof.

[0088] The growth medium can further comprise a cell, such as a nerve cell. The nerve cell can comprise aNaV. e.g., NaV 1.7 or NaV1.8. In some embodiments, the growth medium comprises a nerve cell. In some embodiments, the nerve cell comprises NaV 1.7. In some embodiments, the nen e cell comprises NaV 1.8.

[0089] In certain embodiments, this disclosure relates to a grow th medium comprising a compound of Formula (A), Formula (B), Formula (I) (e.g., a compound of Formula (la), (la- 1), or (la-2)). Formula (II) (e.g., a compound of Formula (e.g., a compound of Formula (Ila), (IIa-1), or (IIa-2)), Formula (III) (e.g., a compound of Formula (Illa)), Formula (IV) (e.g., a compound of Formula (IVa)), Formula (A1)-(A57), a compound of Table 1, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof. In certain embodiments, the growth medium further comprises a cell, e.g., nerve cell or cell expressing a voltage-gated sodium channel gene, e.g., NaV 1.8.

[0090] In certain embodiments, this disclosure relates to a grow th medium comprising a tracer 2-(4-(fluoro- 18F)-2-methylphenoxy)-N-( 1 -(methoxymethy l)-2-oxo- 1 ,2- dihydropyridin-4-yl)-4-(trifluoromethyl)benzamide (Compound B) and / or 2-(4-(fluoro-18F)- 2-methylphenoxy)-N-(2-hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide (Compound C). In certain embodiments, the grow th medium further comprises a cell, e.g., nerve cell or cell expressing a voltage-gated sodium channel gene, e.g.. NaV 1.8.BRIEF DESCRIPTION OF DRAWINGS

[0091] FIG. 1 shows the chemical structures of exemplary Compounds A-C disclosed herein. Compound A has the chemical name N-(l-(methoxymethyl)-2-oxo-l,2-dihydropyridin-4-yl)-2- (2-methyl-4-(4,4,5,5-tetramethyl-l,3,2-dioxaborolan-2-yl)phenoxy)-4- (trifluoromethyl)benzamide. Compound B has the chemical name 2-(4-(fluoro-18F)-2- methylphenoxy)-N-(I-(methoxymethyl)-2-oxo-l,2-dihydropyridin-4-yl)-4- (trifluoromethyl)benzamide. Compound C has the chemical name 2-(4-(fluoro-18F)-2- methylphenoxy)-N-(2-hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide.

[0092] FIG. 2 shows an exemplary route for the synthesis of a reference compound (6), and an exemplary route for the synthesis of a precursor compound (13).

[0093] FIG. 3 shows an exemplary route for the synthesis of Compound C (labeled [18F] 6 in the drawing).

[0094] FIG. 4 is a graph depicting data collected following a whole-body biodistribution of Compound C in CD-I mice. For each organ or tissue along the x axis, the values are provided for the groups of mice euthanized at 5 mins (first bar), 15 mins (second bar), 30 (third bar), and 60 mins (fourth bar).

[0095] FIG. 5 is a graph depicting data collected following a whole-body biodistribution of radiotracer Formula (la-1) in CD-I mice. For each organ or tissue along the x axis, the values are provided for the mice euthanized at 5 mins (first bar), 15 mins (second bar), 30 (third bar), and 60 mins (fourth bar).

[0096] FIG. 6 is a PET image obtained from a mouse that was administered radiotracer Formula (la- 1 ) and subjected to PET imaging, showing sagittal and coronal views.DETAILED DESCRIPTION

[0097] The present disclosure relates to radiotracers and methods of using them, e.g., for the detection and / or quantification of voltage-gated sodium channels (NaVs). In particular, radiotracers disclosed herein can selectively bind to aNaV isoform, e.g., NaV1.7 or NaV1.8,and can be used for selectively detecting and / or quantifying a single NaV isoform. The disclosure also relates to pharmaceutical compositions comprising a radiotracer of the present disclosure. Further, the disclosure relates to methods of preparing radiotracers, and analytical methods for assessing test compounds such as NaV channel blockers. The disclosure also relates to growth mediums, cell cultures, and kits.

[0098] Radiotracers

[0099] The radiotracers of the present disclosure are small molecule compounds covalently bonded to a radionuclide. Radiotracers of the present disclosure can bind to and / or block (or inhibit) voltage-gated sodium channels (NaVs), e.g., NaV1.7 or NaV1.8. It will be understood that the compounds of the present disclosure comprising a radionuclide (e.g.,, 8F) can also be referred to as radiolabeled compounds, tracers, or the like.

[0100] Radiotracers of the present disclosure can selectively bind to a NaV isoform, e.g., a neuronal NaV, such as NaV 1.7 or NaV 1.8. As such, radiotracers of the present disclosure can be referred to as isoform-selective NaV binders. A radiotracer of the present disclosure can exhibit 10-fold selectivity or more for one NaV isoform over remaining NaV isoforms, e.g., 20-fold. 30-fold, 40-fold. 50-fold, 75-fold, 100-fold. 150-fold. 200-fold. 300-fold. 400- fold, 500-fold, 600-fold, 700-fold, 800-fold, 900-fold, 1000-fold, 2000-fold, 5000-fold, 10,000-fold, 20,000-fold, 30,000-fold, or more selectivity7.

[0101] In some embodiments, a radiotracer of the present disclosure selectively binds to NaV 1.7. In some embodiments, a radiotracer of the present disclosure selectively binds to NaV 1.8.

[0102] Radiotracers of the present disclosure comprise a radionuclide selected from the group consisting ofnC,13N,15O,18F,34mCl,38K,45Ti.51Mn,52mMn,52Fe,55Co,60Cu,61Cu,62Cu.64Cu.66Ga.67Ga.68Ga.71As.72As,74As,75Br,76Br,82Rb,86Y,89Zr,90Nb,94mTc,99mTc,110mIn,inIn,118Sb,120I,1211,1221,123I,124I,124I,131I, and2O1T1. In some embodiments, the radionuclide is selected from the group consisting of18F,34mCl,75Br,76Br,120I,121I,122I,123I,124I,124I, and131I. In some embodiments, the radionuclide is18F.

[0103] A radiotracer of the present disclosure can be a radionuclide-containing variant of LTGO-33 ((7?)-2-(4-fluoro-2-methylphenoxy)-N-(3-(S-methylsulfonimidoyl)phenyl)-5- (trifluoromethyl)nicotinamide), or a salt thereof (e.g., a pharmaceutically acceptable salt thereof). Non-radiolabeled LTGO-33 (containing19F-fluorine) is currently under development by Latigo Biotherapeutics, Inc. as a new non-opioid treatment of pain. Nonradiolabeled LTGO-33 has 600-fold selectivity for NaV1.8 over other human NaV isoforms See Gilchrist, et al. Mol. Pharmacol. (2024) 105:233-249), and it is believed that theradiotracer of the present disclosure that is a radionuclide-containing variant of LTGO-33 has substantively similar or the same selectivity for binding NaV 1.8. The variant can comprise the same carbon skeleton as LTGO-33, with the variation being the substitution of a single atom for a radionuclide, for example, the substitution of a single19F atom for an18F atom. A radiotracer of the present disclosure that is a radionuclide-containing variant of LTGO-33 can comprise a radionuclide (e.g.,18F) covalently bonded to any substitutable atom (e.g., a carbon atom). A radiotracer of the present disclosure can be an18F-containing variant of LTGO-33, or a pharmaceutically acceptable salt thereof, where the LTGO-33 structure is modified by substituting the19F group on the phenyl ring with the radioactive18F isotope.

[0104] Another radiotracer of the present disclosure is a radionuclide-containing variant of LTGO-34 ((<SY)-2-(4-fluoro-2-methylphenoxy)-N-(3-(S-methylsulfonimidoyl)phenyl)-5- (trifluoromethyl)nicotinamide), or a pharmaceutically acceptable salt thereof. Nonradiolabeled LTGO-34 (containing19F-fluorine) is also under development by Latigo Biotherapeutics, Inc. as a new non-opioid treatment of pain. LTGO-34 has over 450-fold selectivity for NaV1.8 over other human NaV isoforms. (See Gilchrist, et al. supra). and it is believed that the radiotracer of the present disclosure that is a radionuclide-containing variant of LTGO-34 has substantively similar or the same selectivity for binding NaV1.8. The variant can comprise the same carbon skeleton as LTGO-34, with the variation being the substation of a single atom for a radionuclide, for example, the substitution of a single19F atom for an18F atom. A radiotracer of the present disclosure that is a radionuclide-containing variant of LTGO-34 can comprise a radionuclide (e g.,18F) covalently bonded to any substitutable atom (e.g., a carbon atom). A radionuclide-containing variant of LTGO-34 of the present disclosure can be an18F-containing variant of LTGO-34, where the LTGO-34 structure is modified by substituting the19F group on the phenyl ring with the radioactive18F isotope.

[0105] Another radiotracer of the present disclosure is a radionuclide-containing variant of LTGO-OOl. Yet another radiotracer of the present disclosure is a radionuclide-containing variant of LTGO-305. LTGO-OOl and LTGO-305 are also selective NaV binders being developed by Latigo Biotherapeutics, Inc.

[0106] In some embodiments, a radiotracer of the present disclosure comprises a compound with a structure of Formula (salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof, wherein W is C or N; X is CH or N; Y is C or N; R30is hydrogen, (Ci-C4)-alkyl (e.g., methyl or ethyl), (Cs-Cs)- cycloalkyl (Ci-C4)-haloalkyl (e.g., CF3), optionally substituted heterocyclyl (e.g., morpholinyl), optionally substituted aryl (e.g.. phenyl), optionally substituted heteroaryl (e.g., imidazolyl), or -NH-heterocyclyk R1is aryl or heteroaryl, wherein the aryl or heteroaryl is optionally substituted with one or more groups selected from the group consisting of (C1-C4)- haloalkyl, optionally substituted (Ci-Cs)-alkyl, (C3-Cio)-cycloalkyl, halogen (e.g., F, Cl, or Br, including isotopes thereof such as18F), heteroaryl, cyano, amino, nitro, aryloxyl, aryl, (Ci-C8)-alkyloxyl, (Ci-C4)-haloalkyloxyl, sulfanyl, trifluoromethylsulfanyl, and arylalkoxyl (including, e.g.,18F); R2is selected from the group consisting of aryl, heteroary 1, and heterocyclyl, wherein the aryl, heteroaryl, and heterocyclyl are optionally substituted with one or more groups selected from the group consisting of (Ci-C4)-haloalkyl, optionally substituted (Ci-Cs)-alkyl, (C3-Cio)-cycloalkyl. halogen (e g., F, Cl, or Br. including isotopes thereof such as18F), heteroaryl, cyano, amino, nitro, aryloxyl, aryl, (Ci-Cs)-alkyloxyl, (Ci- C4)-haloalkyloxyl, oxo, alkylsulfinyl, alkylsulfonyl, alkyliminosulfanonyl, alkylsulfoxide, sulfonamide, alkylsulfoximinyl, morpholinyl, oxazolyl, -S(O)(NH)-(Ci-C4)-alkyl (e.g., - S(0)(NH)-CH3), and -S(O)(NMe)-(Ci-C4)-alkyl; when Y is C, R3is selected from the group consisting of hydrogen, cyano, halogen (e.g., F. Cl, or Br. including isotopes thereof such as18F), (Ci-Cs)-alkyoxyl, (Ci-C4)-haloalkyl (e.g., CF3), (Ci-C4)-haloalkyloxyl, (C3-Cs)- cycloalkyl, nitro, haloalkyloxyl; or when Y is N, R3is absent; when W is N, R4is absent; when W is C, R4is selected from the group consisting of hy drogen, cyano, halogen (e.g., F, Cl, or Br, including isotopes thereof such as18F), (Ci-C8)-alkyoxyl. (Ci-C4)-haloalkyl (e.g., CF3), (Ci-C4)-haloalkyloxyl, optionally substituted (Ci-Cs)-alkyl, (C3-C8)-cycloalkyl, and morpholinyl, optionally, wherein R3and R4are not both hydrogen; or R3and R4together form a (C3-C5)-carbocyclic ring (including carbon atoms to which R3and R4are attached); wherein the compound of Formula (A) comprises at least one radionuclide (e.g.,18F). In some embodiments, at least one of W, X, and Y is N. In some embodiments, at least one of X and Y is N.

[0107] In some embodiments, the radiotracer comprises a compound with a structure ofFormula (salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof,, wherein W is C or N; X is CH or N; Y is C or N, provided that at least one of X and Y is N; R30is hydrogen, (Ci-C4)-alkyl (e.g., methyl or ethyl), (C3-Cs)-cycloalkyl (Ci-C4)-haloalkyl (e.g., CF3), optionally substituted heterocyclyl (e.g., morpholinyl), optionally substituted aryl (e.g.. phenyl), optionally substituted heteroaryl (e.g., imidazolyl), or -NH-heterocyclyk R1is aryl or heteroaryl, wherein the aryl or heteroaryl is optionally substituted with one or more groups selected from the group consisting of (Ci-C4)-haloalkyl, optionally substituted (Ci-C8)-alkyl, (C3-Cio)-cycloalkyl, halogen (e.g., F, Cl, or Br, including isotopes thereof such as18F), heteroaryd, cyano, amino, nitro, aryloxyl. aryl, (Ci-C8)-alkyloxyl, (Ci-C4)-haloalkyloxyl, sulfanyl, trifluoromethylsulfanyl, and arylalkoxyl (including, e.g.,18F); R2is selected from the group consisting of aryl, heteroaryl, and heterocyclyl, wherein the aryl, heteroaryl, and heterocyclyl are optionally substituted with one or more groups selected from the group consisting of (Ci- C4)-haloalkyl, optionally substituted (Ci-Cs)-alkyl, (C3-Cio)-cycloalkyl, halogen (e.g., F. Cl, or Br, including isotopes thereof such as18F), heteroaryl, cyano, amino, nitro, aryloxyl, and, (Ci-C8)-alkyloxyl, (Ci-C4)-haloalkyloxyl, oxo, alkylsulfinyl, alkylsulfonyl, alkydiminosulfanonyl, alkydsulfoxide, sulfonamide, alkylsulfoximinyl, morpholinyl, oxazolyl, -S(O)(NH)-(Ci-C4)-alkyl (e.g., -S(O)(NH)-CH3), and -S(O)(NMe)-(Ci-C4)-alkyl; when Y is C, R3is selected from the group consisting of hydrogen, cyano, halogen (e.g., F, Cl, or Br. including isotopes thereof such as18F), (Ci-Cs)-alkyoxyl, (Ci-C4)-haloalkyl (e.g., CF3), (Ci- C4)-haloalkyloxyl, (C3-Cs)-cycloalkyd, nitro, haloalk doxyl; or when Y is N, R3is absent; when W is N, R4is absent: when W is C, R4is selected from the group consisting of hydrogen, cyano, halogen (e.g., F, Cl, or Br. including isotopes thereof such as18F), (Ci-Cs)- alkyoxyl, (Ci-C4)-haloalkyl (e.g., CF3), (Ci-C4)-haloalkyloxyl, optionally substituted (Ci-Cs)- alkyl, (C3-Cs)-cycloalkyl, and morpholinyl, provided that R3and R4are not both hydrogen; or R3and R4together form a (C3-Cs)-carbocyclic ring (including carbon atoms to which R3and R4are attached); wherein the compound of Formula (A) comprises at least one radionuclide.

[0108] In some embodiments of the compound of Formula (A), or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof,, X is CH or N; Y is C or N;R1is selected from the group consisting of phenyl or pyridinyl, wherein the phenyl or pyridinyl is optionally substituted with one or more groups selected from the group consisting of optionally substituted (Ci-C8)-alkyl, halogen (e.g., F, Cl, or Br, including isotopes thereof such as18F), -O-R5, wherein R5is selected from the group consisting of (Ci-Cs)-alkyl, -CF3, -CHF2, and -(CH2)P-CF3, wherein p is an integer of 1-8, and -S-CF3; R2is selected from the group consisting of phenyl, pyridyl, pyrimidinyl, pyridazinyl. pyrazolyl, pyridine-1 -oxide, 1,2,3-thiadiazolyl, 1,2,4-triazolyl, 1,3-benzothiazolyl, and partially or fully saturated forms thereof (e.g., dihydropyridinyl or tetrahydropyridinyl), wherein the phenyl, pyridyl, pyrimidinyl, pyridazinyl, pyridine-l-oxide, 1,2,3-thiadiazolyl, 1,2,4-triazolyl, 1,3- benzothiazolyl, and partially or fully saturated forms thereof, are optionally substituted with one or more groups selected from the group consisting of unsubstituted or substituted (Ci- C5)-alkyl, halogen (e.g., F, Cl, or Br, including isotopes thereof such as18F), cyano, oxo, -O- R5, wherein R5is selected from the group consisting of (Ci-Cs)-alkyl, -CFs, -CHF2, -(CH2)q- OH, wherein q is an integer of 1-8, -NR6AR7A, wherein R6Aand R7Aare selected from the group consisting of H and (Ci-C4)-alkyl, morpholinyl, oxazolyl, -C(O)-R8, wherein R8is selected from the group consisting of -NR6BR7B, wherein R6Band R7Bare selected from the group consisting of H and (Ci-C4)-alkyl, -S(O)-R9, -S(O)2-R9, -S(O)(NR10)-R11, and - N=S(O)-(Rn)2, wherein each R9is independently (Ci-C4)-alkyl, -CF3, or -NR6CR7C, wherein R6Cand R7Care selected from the group consisting of H and (Ci-C4)-alkyl, R10is H or (Ci- C4)-alkyl, and R11is (Ci-C4)-alkyl, provided that when Y is N and R2is phenyl or pyridyl, R8is not -NR6BR7B; when Y is C, R3is selected from the group consisting of hydrogen, cyano, halogen (e.g., F, Cl, or Br, including isotopes thereof such as18F), -CF3, (Ci-Cs)-alkoxyl, -O- CH(F)2, optionally substituted (Ci-Cs)-alkyl, (C3-Cs)-cycloalkyl, nitro; or when Y is N, R3is absent; when W is N, R4is absent; when W is C, R4is selected from the group consisting of hydrogen, cyano, halogen (e.g., F, CL or Br, including isotopes thereof such as18F), (Ci-Cs)- alkoxyl, -CF3, optionally substituted (Ci-Cs)-alkyl, and morpholinyl, optionally wherein R3and R4are not each hydrogen; or R3and R4together form a (C3-C5)-carbocyclic ring including carbon atoms to which R3and R4are attached.

[0109] In some embodiments of the compound of Formula (A), or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof,, X is CH or N; Y is C or N, provided that at least one of X and Y is N; R1is selected from the group consisting of phenyl or pyridinyl, wherein the phenyl or pyridinyl is optionally substituted with one or more groups selected from the group consisting of optionally substituted (Ci-Cs)-alkyl, halogen (e.g., F, Cl, or Br, including isotopes thereof such as18F), -O-R5, wherein R5is selected fromthe group consisting of (Ci-Cs)-alkyl, -CF3, -CHF2, and - (CH2)P-CF3, wherein p is an integer of 1-8, and -S-CF3; R2is selected from the group consisting of phenyl, pyridyl, pyrimidinyl, pyridazinyl, pyrazolyl, pyridine- 1 -oxide, 1,2,3 -thiadi azolyl, 1,2,4-triazolyl, and1.3-benzothiazolyl, wherein the phenyl, pyridyl, pyrimidinyl, pyridazinyl, pyridine-l-oxide,1.2.3-thiadiazolyl, 1,2,4-triazolyl, and 1,3-benzothiazolyl are optionally substituted with one or more groups selected from the group consisting of unsubstituted or substituted (Ci-C5)-alkyl, halogen (e.g., F, Cl, or Br, including isotopes thereof such as18F), cyano, oxo, -O-R5, wherein R5is selected from the group consisting of (Ci-Cs)-alkyl, -CF3, -CHF2, -(CH2)q- OH, wherein q is an integer of 1-8, -NR6AR7A, wherein R6Aand R7Aare selected from the group consisting of H and (Ci-C4)-alkyl, morpholinyl, oxazolyl, -C(O)-R8, wherein R8is selected from the group consisting of -NR6BR7B, wherein R6Band R7Bare selected from the group consisting of H and (Ci-C4)-alkyl, -S(O)-R9, -S(O)2-R9, -S(O)(NR10)-R11, and - N=S(O)-(Rn)2, wherein each R9is independently (Ci-C4)-alkyl, -CFs, or -NR6CR7C, wherein R6Cand R7Care selected from the group consisting of H and (Ci-C4)-alkyl, R10is H or (Ci- C4)-alkyl, and R11is (Ci-C4)-alkyl, provided that when Y is N and R2is phenyl or pyridyl, R8is not -NR6BR7B; when Y is C, R3is selected from the group consisting of hydrogen, cyano, halogen (e.g., F, Cl, or Br, including isotopes thereof such as18F), -CF3, (Ci-Cs)-alkoxyl, -O- CH(F)2, optionally substituted (Ci-Cs)-alkyl, (C3-Cs)-cycloalkyl, nitro; or when Y is N, R3is absent; when W is N, R4is absent; when W is C, R4is selected from the group consisting of hydrogen, cyano, halogen (e.g., F. Cl, or Br. including isotopes thereof such as18F), (Ci-Cs)- alkoxyl, -CF3, optionally substituted (Ci-Cs)-alkyl, and morpholinyl, provided that R3and R4are not each hydrogen; or R3and R4together form a (C3-C5)-carbocyclic ring including carbon atoms to which R3and R4are attached.

[0110] In some embodiments, R1is aryl or heteroaryl, wherein the aryl or heteroaryl is substituted with one or more halogen atoms, e.g., F, CL or Br, including isotopes thereof such as18F. In some embodiments, R1is aryl or heteroaryl, wherein the aryl or heteroaryl is substituted with18F.

[0111] In some embodiments, the radiotracer comprises a compound with a structure ofFormula (salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof,, wherein W is C or N; X is CH or N; Y is C or N; R30is hydrogen, (Ci-C4)-alkyl (e.g., methyl or ethyl), (C3-C8)-cycloalkyl (C1-C4)- haloalkyl (e.g., CF3). optionally substituted heterocyclyl (e.g., morpholinyl), optionally- substituted aryl (e.g.. phenyl), optionally substituted heteroaryl (e.g., imidazolyl), or -NH- heterocyclyl; R2is selected from the group consisting of aryl, heteroaryl, and heterocyclyl, wherein the aryl, heteroaryl, and heterocyclyl are optionally substituted with one or more groups selected from the group consisting of (C i-C4)-haloalkyl, optionally substituted (Ci-Cs)-alkyl, (C3-Cio)-cycloalkyl. halogen (e.g., F, Cl, or Br. including isotopes thereof such as18F), heteroaryl, cyano, amino, nitro, aryloxyl. aryl, (Ci-Cs)-alkyloxyl, (Ci-C4)-haloalkyloxyl, oxo, alkylsulfinyl, alkylsulfonyl, alkyliminosulfanonyl, alkylsulfoxide, sulfonamide, alkylsulfoximinyl, morpholinyl, oxazolyl, -S(0)(NH)-(Ci-C4)-alkyl (e.g., -S(0)(NH)-CH3), and -S(0)(NMe)-(Ci-C4)-alkyl; when Y is C, R3is selected from the group consisting of hydrogen, cyano, halogen (e.g., F, CL or Br, including isotopes thereof such as18F), (Ci-Cs)- alkyoxyl, (Ci-C4)-haloalkyl (e.g., CF3), (Ci-C4)-haloalkyloxyl, (C3-Cs)-cycloalkyl. nitro haloalkyloxyl; or when Y is N, R3is absent; when W is N, R4is absent; when W is C, R4is selected from the group consisting of hydrogen, cyano, halogen (e.g., F, Cl, or Br, including isotopes thereof such as18F), (Ci-C8)-alkyoxyl, (Ci-C4)-haloalkyl (e.g.. CF3). (C1-C4)- haloalkyloxyl, optionally substituted (Ci-Cs)-alkyl, (C3-C8)-cycloalkyl, and morpholinyl, optionally wherein R3and R4are not both hydrogen; or R3and R4together form a (C3-C5)- carbocyclic ring (including carbon atoms to which R3and R4are attached); n is an integer of 0-5; and each instance of R24is independently selected from the group consisting of (C1-C4)- haloalkyl, (Ci-Cs)-alkyl, (C3-Cio)-cycloalkyl, halogen (e.g., F, Cl, or Br, including isotopes thereof such as18F), heteroaryl, cyano, amino, nitro, ary loxyl, ary l, (Ci-C8)-alkyloxyl, (Ci- C4)-haloalkyloxyl, sulfanyl, trifluoromethylsulfanyl, and arylalkoxyl; wherein the compound of Formula (Al) comprises at least one radionuclide (e.g.,18F).

[0112] In some embodiments, the radiotracer comprises a compound with a structure ofFormula (salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof,, wherein W is C or N; X is CH or N; Y is C or N, provided that at least one of X and Y is N; R30is hydrogen, (Ci-C4)-alkyl (e.g., methyl or ethyl), (C3-Cs)-cycloalkyl (Ci-C- -haloalkyl (e.g., CFs). optionally substituted heterocyclyl (e.g., morpholinyl), optionally substituted aryl (e.g., phenyl), optionally substituted heteroaryl (e g., imidazolyl), or -NH-heterocyclyl; R2is selected from the group consisting of aryl, heteroaryl, and heterocyclyl, wherein the and, heteroar l. and heterocyclyl are optionally substituted with one or more groups selected from the group consisting of (Ci-C4)-haloalkyl, optionally substituted (Ci-Cs)-alkyl. (C3-Cio)-cycloalkyl, halogen (e.g.. F, Cl, or Br, including isotopes thereof such as18F), heteroaryl, cyano, amino, nitro, aiyloxyl, aryl, (Ci-Cs)- alkyloxyl, (Ci-C4)-haloalkyloxyl, oxo, alkylsulfinyl, alkylsulfonyl, alky liminosulfanonyl, alkylsulfoxide, sulfonamide, alkylsulfoximinyl, morpholinyl, oxazolyl, -S(O)(NH)-(CI-C4)- alkyl (e.g., -S(0)(NH)-CH3), and -S(O)(NMe)-(Ci-C4)-alkyl; when Y is C, R3is selected from the group consisting of hydrogen, cyano, halogen (e.g., F, CL or Br, including isotopes thereof such as18F), (Ci-C8)-alkyoxyl, (Ci-Ci)-haloalky 1 (e.g., CF3), (Ci-C4)-haloalkyloxyl, (C3-Cs)-cycloalkyl, nitro haloalky loxyl; or when Y is N, R3is absent; when W is N, R4is absent; when W is C, R4is selected from the group consisting of hydrogen, cyano, halogen (e.g.. F, Cl. or Br, including isotopes thereof such as18F). (Ci-Cs)-alkyoxyl, (Ci-C4)-haloalkyl (e.g., CF3), (Ci-C4)-haloalkyloxyl, optionally substituted (Ci-Cs)-alkyl, (C3-C8)-cycloalkyl, and morpholinyl, provided that R3and R4are not both hydrogen; or R3and R4together form a (C3-Cs)-carbocyclic ring (including carbon atoms to which R3and R4are attached); n is an integer of 0-5; and each instance of R24is independently selected from the group consisting of (Ci-C4)-haloalkyl, (Ci-C8)-alkyl, (C3-Cio)-cycloalkyl, halogen (e.g., F, Cl, or Br, including isotopes thereof such as18F), heteroaryl, cyano, amino, nitro, aryloxyl, aryl, (Ci-Cs)- alkyloxyl, (Ci-C4)-haloalky loxyl, sulfanyl, trifluoromethylsulfanyl, and ary lalkoxyl; wherein the compound of Formula (Al) comprises at least one radionuclide.

[0113] In some embodiments, at least one R24is present and is halogen (e.g.,18F).

[0114] In some embodiments, R1comprises the structure:. wherein R29is selected from the group consisting of optionally substituted (Ci-Cs)-alkyl, halogen, -O-R5, wherein R5is selected from the group consisting of (Ci-Cs)-alkyl, -CF3, -CHF2, and -(CH2)P-CF3, wherein n is an integer of 0-4, and wherein p is an integer of 1-8.

[0115] In some embodiments, R1is selected from a group consisting of, wherein m is an integer of 0-4; R25is selected from the group consisting of H, morpholinyl, oxazolyl. halogen, cyano, -(CH2)q-OH, wherein q is an integer of 1-8, -C(O)- R8, -S(O)2-CH3, and -S(O)(NH)-CH3; R26is halogen or cyano; each R27is independently selected from the group consisting of hydrogen, halogen, (Ci-C4)-alkoxyl, cyano, -and NR6DR7D; each R28is independently H or (Ci-C4)-alkyl; R8is selected from the group consisting of-NR6DR7Dand (Ci-C4)-alkyl, wherein R6Dand R7Dare selected from the group consisting of hydrogen, (Ci-C4)-alkyl. -S(O)-R9, -S(O)2-R9, -S(O)(NR10)-Rn, and -N=S(O)- (Rn)2, wherein each R9is independently (Ci-C4)-alkyl, -CF3, or -NR6ER7E, wherein R6Eand R7Eare selected from the group consisting of hydrogen and (Ci-C4)-alkyl; R10is hydrogen or (Ci-C4)-alkyl; and R11is (Ci-C4)-alkyl, provided that when Y is N and R2is phenyl or pyridyl, R8is not -NR6DR7D.

[0117] In some embodiments, R2is selected from a group consistingany of the above structures can exist in a tautomeric form. For example,can exist as its tautomer

[0120] In some embodiments, the radiotracer comprises a compound with a structure ofpharmaceutically acceptable salt thereof, wherein each

[0122] In some embodiments, the radiotracer comprises a compound with a structure of

[0123] In some embodiments, the radiotracer comprises a compound with a structure oft thereof, wherein each

[0124] In some embodiments, the radiotracer comprises a compound with a structure of

[0125] In some embodiments, the radiotracer comprises a structure of Formula (I):salt thereof (e g., a pharmaceutically acceptable salt thereof), or a tautomer thereof, wherein X is a radionuclide (e.g.,18F). For example, the structure of the radiotracer can be that of Formula (salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof. The structure of the radiotracer can be that of Formulaor a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof. The structure of the radiotracer can be that of Formulaa salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof.

[0126] A radiotracer of the present disclosure can be a compound that comprises a structure ofFormulasalt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof, wherein X is a radionuclide (e.g.,18F). In some embodiments, the radionuclide is18F.

[0127] The radiotracer of Formula (IV) can be a compound that comprises a structure ofFormulasalt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof.

[0128] In some embodiments, the radiotracer is a compound with a structure selected from Table 1, or a pharmaceutically acceptable salt thereof.

[0129] Table 1. Exemplary radiotracers.

[0130] A radiotracer of the present disclosure can be a compound that comprises a structure ofsalt thereof (e.g., a pharmaceutically acceptablesalt thereof), or a tautomer thereof, wherein X is a radionuclide (e.g.,18F). In some embodiments, the radionuclide is18F. It will be understood that the compound can exist in its tautomeric form:

[0131] A radiotracer of the present disclosure can be Compound C:(Compound C: 2-(4-(fluoro-18F)-2-methylphenoxy)-N-(2- hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide), or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof. It will be understood thatCompound C can exist in its tautomeric form:

[0132] A radiotracer of the present disclosure can be Compound (B):(Compound B; 2-(4-(fluoro-18F)-2-methylphenoxy)-N-(l-(methoxymethyl)-2-oxo-l,2-dihydropyridin-4-yl)-4- (trifluoromethyl)benzamide) or a salt thereof (e.g. , a pharmaceutically acceptable salt thereof), or a tautomer thereof.

[0133] A radiotracer of the present disclosure can be a radionuclide-containing variant of a NaV-binding compound disclosed in WO 2020 / 014246 or WO 2022 / 192487, each of which are incorporated herein by reference in their entireties, and the radionuclide can be18F. The variant can comprise the same carbon skeleton as a compound disclosed in WO 2020 / 014246 or WO 2022 / 192487, w ith the variation being the substitution of a single atom for a radionuclide, for example, the substitution of a single19F atom for an18F atom. In some embodiments, the radiotracer is an18F-containing variant of a NaV-binding19F-containing compound disclosed in WO 2020 / 014246, where the NaV-binding compound is modified by substituting the19F atom on the compound with the radioactive18F isotope. In some embodiments, the radiotracer is an18F-containing variant of a NaV-binding19F-containing compound disclosed in WO 2022 / 192487. where the NaV-binding compound is modified by substituting the19F atom on the compound with the radioactive18F isotope.

[0134] Another radiotracer of the present disclosure is a radionuclide-containing variant of suzetrigine (VX-548, or ((2R,3S,4S,5R)-4-[[3-(3,4-difluoro-2-methoxy-phenyl)-4,5- dimethy 1-5 -(trifluoromethyl) tetrahydrofuran-2-carbonyl]amino]pyridine-2-carboxamide, or a pharmaceutically acceptable salt thereof. Suzetrigine (containing19F -fluorine) is currently under development by Vertex Pharmaceuticals Inc. for treating acute and neuropathic pain. Suzetrigine has over 30,000-fold selectivity7for NaV1.8 over other human NaV isoforms (See Jones, et al. N. Engl. J. Med. (2023) 389(5):393-405), and it is believed that the radiotracer of the present disclosure that is a radionuclide-containing variant of suzetrigine has substantively similar or the same selectivity for binding NaVl .8. The variant can comprise the same carbon skeleton as suzetrigine, with the variation being the substitution of a single atom for a radionuclide, for example, the substitution of a single19F atom for an18F atom. A radiotracer of the present disclosure that is a radionuclide-containing variant of suzetrigine can comprise a radionuclide (e.g.,18F) covalently bonded to any substitutable atom (e.g., a carbon atom). A radionuclide-containing variant of suzetrigine of the present disclosure can be an18F -containing variant of suzetrigine, where the suzetrigine structure is modified by substituting a19F atom on the phenyl ring with the radioactive18F isotope.

[0135] In some embodiments, the radiotracer comprises a structure of Formula (II):salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof, wherein one of Xaand Xbis a radionuclide (e.g.,18F), and the other of Xaand Xbis a stable F isotope (i. e. ,19F). For example, one of Xaand Xbcan be18F, and the other of Xaand Xbcan be a stable F isotope (i.e.,19F). The radiotracer can comprise a structure of Formulasalt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof, wherein one of Xaand Xbis a radionuclide (e.g.,18F), and the other of Xaand Xbis a stable F isotope. For example, one of Xaand Xbcan be18F, and the other of Xaand Xbcan be a stable F isotope. The radiotracer can comprise a structure of Formulasalt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof. The radiotracer can comprise a structure of Formulaor a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof.

[0136] In some embodiments, a radiotracer of the present disclosure is a radionuclidecontaining variant of a NaV-binding compound disclosed in WO 2021 / 113627, which is incorporated herein by reference in its entirety, and the radionuclide can be18F. The variantcan comprise the same carbon skeleton as a compound disclosed in WO 2021 / 113627, with the variation being the substitution of a single atom for a radionuclide, for example, the substitution of a single19F atom for an18F atom. In some embodiments, the radiotracer is an18F-containing variant of aNaV-binding19F-containing compound disclosed in WO 2021 / 113627, where the NaV-binding compound is modified by substituting the19F atom on the compound with the radioactive18F isotope.

[0137] Another radiotracer of the present disclosure is a radionuclide-containing variant of PF-05089771 (4-[2-(3-amino-l / 7-pyrazol-4-yl)-4-chlorophenoxy]-5-chloro-2-fluoro-N-(l,3- thiazol-4-yl)benzene-l -sulfonamide). PF-05089771 (containing19F-fluorine) is under development by Pfizer as an orally administered analgesic. PF-05089771 selectively binds to Navi.7, and is 11-fold, 16-fold, and 59-fold selective over the NaV 1.2. NaV1.6, and NaVl. l channels, respectively, and greater than or equal to 909-fold selective over Navi .3, Navi .4, Navi.5, and Navi.8 (See Siebenga, et al. Clin. Transl. Sci. (2020) 13:318-324), and it is believed that the radiotracer of the present disclosure that is a radionuclide-containing variant of PF-05089771 has substantively similar or the same selectivity for binding NaV1.7. The variant can comprise the same carbon skeleton as PF-05089771, with the variation being the substitution of a single atom for a radionuclide, for example, the substitution of a single19F atom for an18F atom. A radiotracer of the present disclosure that is a radionuclide-containing variant of PF-05089771 can comprise a radionuclide (e.g.,18F) covalently bonded to any substitutable atom (e.g., a carbon atom). A radionuclide-containing variant of PF-05089771 of the present disclosure is an18F-containing variant of PF-05089771, where the PF- 05089771 structure is modified by substituting the19F atom on the phenyl ring with the radioactive18F isotope.

[0138] PF-05089771 was developed as an orally available NaV 1.7 inhibitor, and while it demonstrated analgesic efficacy in clinical trials, it also significantly increased cholesterol in a Phase 2 study (NCT02215252). It is therefore an advantage of the radionuclide-containing variant of PF-05089771 of the present disclosure that it can be administered at dosages that are magnitudes lower than the therapeutic dose, and nevertheless be useful for the diagnostic and analytical methods disclosed herein. For example, the radiotracer can be used in a method of the present disclosure at a single dose as low as 20 micrograms, whereas therapeutic dosing in subjects was at 300 milligrams daily. Without wishing to be bound by theory', it is believed that this lower dosing of the presently disclosed methods reduces the likelihood of subjects experiencing side effects or toxicity.

[0139] In some embodiments, the radiotracer comprises a structure of Formula (III):salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof, wherein X is a radionuclide (e.g.,18F). The radiotracer can comprise a structure of Formula (Illa):salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof.

[0140] In some embodiments, a radiotracer of the present disclosure is a radionuclidecontaining variant of aNaV-binding compound disclosed in WO 2010 / 079443, which is incorporated herein by reference in its entirety, and the radionuclide can be18F. The variant can comprise the same carbon skeleton as a compound disclosed in WO 2010 / 079443, with the variation being the substitution of a single atom for a radionuclide, for example, the substitution of a single19F atom for an18F atom. In some embodiments, the radiotracer is an18F-containing variant of aNaV-binding19F-containing compound disclosed in WO 2010 / 079443, where the NaV-binding compound is modified by substituting the19F atom on the compound with the radioactive18F isotope.

[0141] A radiotracer of the present disclosure can comprise a specific activity of about 0.2 Ci / pmol or greater, e.g., between about 0.4 Ci / pmol and about 20 Ci / pmol, between about 0.4 Ci / pmol and about 10 Ci / pmol, between about 0.4 Ci / pmol and about 5 Ci / pmol. or between about 0.4 Ci / pmol and about 3 Ci / pmol; e.g., about 0.4 Ci / pmol, about 0.6 Ci / pmol, about 0.8 Ci / pmol, about 1.0 Ci / pmol, about 1.2 Ci / pmol, about 1.4 Ci / pmol, about 1.6 Ci / pmol, about 1.8 Ci / pmol, about 2.0 Ci / pmol, about 2.2 Ci / pmol, about 2.4 Ci / pmol, about 2.6 Ci / pmol, about 2.8 Ci / pmol, about 3.0 Ci / pmol. about 3.5 Ci / pmol. about 4.0 Ci / pmol. about 4.5 Ci / pmol, about 5.0 Ci / pmol, about 6.0 Ci / pmol, about 7.0 Ci / pmol, about 8.0 Ci / pmol, about 9.0 Ci / pmol, about 10 Ci / pmol, about 12 Ci / pmol, about 14 Ci / pmol, about 16 Ci / pmol, about 18 Ci / pmol, about 20 Ci / pmol, or greater.

[0142] Without wishing to be bound by theory', it is believed that the substitution of the stable fluoro group (19F) present on the aforementioned NaV blockers with the radioactive18Fisotope does not alter the selectivity or ability of the compounds to bind to NaV1.7 or NaV1.8. However, it will be understood by those having ordinary skill in the art that these radiotracers are not suitable alternatives to the non-radiolabeled counterparts for use in therapeutic methods, such as analgesia and methods of treating pain, e.g., due to the instability' and short half-lives of the radionuclide. For example, the18F isotope has a halflife of only 109.7 minutes. The inventors discovered that the incorporation of a radionuclide (e.g., an18F isotope) advantageously makes the radiotracers of the present disclosure useful as probes for diagnostic and analytical methods, such as selectively detecting and imaging NaV isoforms, e.g., when coupled with a suitable imaging technique such as PET. Indeed, a particular advantage of the radiotracers of the present disclosure is their ability to selectively bind to a particular NaV isoform (e.g.. NaV 1.7 or NaV 1.8). which provides the ability to identify those NaV isoforms selectively, e.g., in vivo. Yet another advantage of the radiotracers is that large, or repeated, doses that are typically required for therapeutic doses are not needed when using the radiotracers of the present disclosure, e.g., for diagnostic or analytical purposes, and the radiotracers can be administered (e.g., intravenously) in very’ loyv doses that avoids undesirable side-effects or noticeable pharmacological effects (e.g., loss of feeling or movement) in the subject.

[0143] Pharmaceutical Compositions

[0144] The present disclosure provides pharmaceutical compositions comprising a radiotracer disclosed herein, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof, and optionally a pharmaceutically acceptable excipient.

[0145] In some aspects, a pharmaceutical composition described herein comprises radionuclide-containing variant of LTGO-33 (e.g., an18F-containing variant of LTGO-33), or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof, and optionally a pharmaceutically acceptable excipient. In some aspects, a pharmaceutical composition described herein comprises radionuclide-containing variant of LTGO-34 (e.g., an18F-containing variant of LTGO-34), or a salt thereof (e.g.. a pharmaceutically acceptable salt thereof), or a tautomer thereof, and optionally a pharmaceutically acceptable excipient. In some aspects, a pharmaceutical composition described herein comprises radionuclidecontaining variant of LTGO-OOl (e.g., an18F-containing variant of LTGO-OOl), or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof, and optionally a pharmaceutically acceptable excipient. In some aspects, a pharmaceutical composition described herein comprises radionuclide-containing variant of LTGO-305 (e.g.,an18F-containing variant of LTGO-305), or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof, and optionally a pharmaceutically acceptable excipient. In some aspects, a pharmaceutical composition described herein comprises a compound of Formula (I), e.g., a compound of Formula (la), (la-1 ), or (la-2), or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof, and optionally a pharmaceutically acceptable excipient. In some aspects, a pharmaceutical composition described herein comprises a compound of Formula (IV), (IV a), (Al), (A1)-(A55), or a compound of Table 1, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof, and optionally a pharmaceutically acceptable excipient. In some aspects, a pharmaceutical composition described herein comprises a compound of Formula (V), (A56), (A57), or a salt thereof (e.g.. a pharmaceutically acceptable salt thereof), or a tautomer thereof, and optionally a pharmaceutically acceptable excipient.

[0146] In some aspects, a pharmaceutical composition disclosed herein comprises a compound of Formula (A), Formula (B), Formula (I) (e.g., a compound of Formula (la), (la- 1), or (la-2)). Formula (II) (e.g., a compound of Formula (e.g., a compound of Formula (Ila), (IIa-1), or (IIa-2)), Formula (III) (e.g., a compound of Formula (Illa)), Formula (IV) (e.g., a compound of Formula (IVa)), Formula (A1)-(A57), a compound of Table I, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof, and optionally a pharmaceutically acceptable excipient.

[0147] In some aspects, a pharmaceutical composition described herein comprises Compound C, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof, and optionally a pharmaceutically acceptable excipient. In some aspects, a pharmaceutical composition described herein comprises Compound B, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof, and optionally a pharmaceutically acceptable excipient.

[0148] In some aspects, a pharmaceutical composition described herein comprises radionuclide-containing variant of suzetrigine (e.g., an18F-containing variant of suzetrigine), or a pharmaceutically acceptable salt thereof, and optionally a pharmaceutically acceptable excipient. In some aspects, a pharmaceutical composition described herein comprises a compound of Formula (II), e.g., a compound of Formula (Ila), (Ila- 1), or (Ila- 2), or a pharmaceutically acceptable salt thereof, and optionally a pharmaceutically acceptable excipient.

[0149] In some aspects, a pharmaceutical composition described herein comprises radionuclide-containing variant of PF-05089771 (e.g., an18F-containing variant of PF-05089771), or a pharmaceutically acceptable salt thereof, and optionally a pharmaceutically acceptable excipient. In some aspects, a pharmaceutical composition described herein comprises a compound of Formula (III), e.g., a compound of Formula (Illa), or a pharmaceutically acceptable salt thereof, and optionally a pharmaceutically acceptable excipient.

[0150] A pharmaceutical composition of the present disclosure may be prepared by any suitable method known in the art. Such methods can involve a step of bringing the radiotracer, or a pharmaceutically acceptable salt thereof, into association with one or more pharmaceutically acceptable excipients (e.g., a carrier or binding agent, e.g., water and / or ethanol), and may further involve a step of shaping and / or packaging the composition into a single- or multi-dose unit.

[0151] Relative amounts of the radiotracer, and the one or more pharmaceutically acceptable excipients, in a pharmaceutical composition of the present disclosure will vary depending on several factors, including the identity', size, and / or condition of the subject or sample to be administered the composition, and also depending on the route by which the composition is to be administered. For example, the pharmaceutical composition may comprise between about 0. 1 wt% and about 100 wt% of the radiotracer.

[0152] Radiotracers or pharmaceutical compositions of the present disclosure may be administered by any suitable technique known in the art, such as direct injection. Injection may be an intravenous (IV) injection. Administration may be general or local to the site of interest. Radiotracers or pharmaceutical compositions of the present disclosure may be administered orally, parenterally (including, without limitation, subcutaneously, intramuscularly, intravenously, and intradermally), by inhalation (e.g., oral inhalation), topically, rectally, nasally, buccally, vaginally, or by an implanted reservoir. Preferably, the radiotracer or pharmaceutical composition is administered parenterally, e.g., intravenously, subcutaneously, intramuscularly, intradermally, intrathecally, intra-articularly, or intraarterially. In some embodiments, the radiotracer, pharmaceutical salt thereof, or pharmaceutical composition thereof, is administered intravenously. In some embodiments the radiotracer, pharmaceutical salt thereof, or pharmaceutical composition thereof is not administered orally.

[0153] The radiotracer may be used in conjunction with another probe, for example a fluorescent probe. The two (or more) probes may be administered together, separately, or sequentially. The tracer of the present disclosure may be used to diagnose, assess, or monitorthe progression or treatment of a disease or condition reported herein, such as pain, epilepsy, seizures movement disorders, cognitive disorders, and neurodegenerative disorders.

[0154] A pharmaceutical compositions of the present disclosure can comprise any suitable pharmaceutically acceptable excipient, such as a pharmaceutically acceptable excipient disclosed herein. In some embodiments, the one or more pharmaceutically acceptable excipients comprise water. In some embodiments, the one or more pharmaceutically acceptable excipients comprise ethanol. In some embodiments, the one or more pharmaceutically acceptable excipients comprise a combination of water and ethanol.

[0155] Pharmaceutical compositions of the present disclosure may be administered (e.g., intravenously) in any acceptable dosage form including, without limitation, aqueous solutions. Intravenous dosage forms can include a pharmaceutically acceptable excipient (e.g., a pharmaceutically acceptable excipient disclosed herein), e.g., carriers, diluents, or the like, such as water and / or ethanol.

[0156] It will be understood that the pharmaceutical compositions of the present disclosure are suitable for administration to humans, but also for administration to other animals, and also other organisms or samples (e.g., cells or tissue samples). It will also be understood that modifications of pharmaceutical compositions are possible to render the compositions suitable for administration to various animals, other organisms, samples, and the ordinarily skilled person can design and / or perform such modification with ordinary experimentation.

[0157] Radiotracers and pharmaceutical compositions disclosed herein can be formulated in a dosage unit form, e.g., a single unit dosage form, for ease of administration or uniformity of dosage. However, it will be understood that the dosage of the radiotracers or compositions of the present disclosure will be decided by the attending physician or researcher within the scope of sound medical judgment.

[0158] A radiotracer or pharmaceutical composition disclosed herein may be formulated or administered to provide a total dose of betw een about 1 mCi and about 30 mCi (e.g., about 1 mCi, about 2 mCi, about 4 mCi, about 6 mCi, about 8 mCi, about 10 mCi, about 15 mCi, about 20 mCi, about 25 mCi, or about 30 mCi). A radiotracer or pharmaceutical composition disclosed herein may be administered as a bolus dose, as an infusion, or a combination thereof. For example, a radiotracer or pharmaceutical composition disclosed herein may be administered as a bolus dose of between about 1 mCi and about 15 mCi (e.g., about 1 mCi, about 2 mCi, about 3 mCi, about 4 mCi, about 5 mCi, about 6 mCi, about 7 mCi, about 8 mCi, about 9 mCi, about 10 mCi, about 11 mCi, about 12 mCi, about 13 mCi, about 14 mCi, or about 15 mCi), follow ed by an infused dose of between about 1 mCi and about 10 mCi(e.g., about 1 mCi, about 2 mCi, about 3 mCi, about 4 mCi, about 5 mCi, about 6 mCi, about 7 mCi, about 8 mCi, about 9 mCi, or about 10 mCi). It will be understood that the term “mCi” refers to “millicurie,” a unit of radioactivity.

[0159] A pharmaceutical composition of the present disclosure can have a radiochemical purity of between about 20% and about 100%, e.g., between about 30% and about 100%, between about 40% and about 100%, between about 50% and about 100%, between about 60% and about 100%, between about 70% and about 100%, between about 80% and about 100%, between about 90% and about 100%, between about 95% and about 100%, or between about 98% and about 100%.

[0160] A radiotracer or composition of the present disclosure can be administered concurrently with, prior to, or subsequent to, one or more additional pharmaceutical agents (e.g., also referred to herein as a test compound), which can be useful, e.g., to monitor treatment with the one or more additional pharmaceutical agents, or monitor the abi 1 i ty of the pharmaceutical agent to bind to a target, such as aNaV (e.g., Navi.7 or NaV1.8).Pharmaceutical agents include therapeutically active agents. Pharmaceutical agents also include prophylactically active agents. Each additional pharmaceutical agent may be administered at a dose and / or at a time determined for that pharmaceutical agent. The additional pharmaceutical agents may also be administered together with each other and / or with the compound or composition described herein in a single dose or administered separately in different doses. The particular combination to employ in a regimen will take into account compatibility of the inventive compound with the additional pharmaceutical agents and / or the desired therapeutic and / or prophylactic effect to be achieved.

[0161] The pharmaceutical composition can have a pH value close to physiologic pH (e.g., approximately pH 7). The pharmaceutical composition can have a pH greater than about 5. For example, the pH value of the composition may be about 4 to about 8.5, e.g., about 5 to about 8.5. The pH value of the pharmaceutical composition can be regulated or adjusted by any suitable means know n to those of skill in the art. The composition can be buffered or the pH value adjusted by addition of acid or base.

[0162] A radiotracer or pharmaceutical composition of the present disclosure is typically- administered once, but could be repeated in daily / weekly / monthly / y early intervals, such as to measure NaV expression or activity changes over time. Thus, the administration can occur a plurality of times, for example to monitor the disease state or response to therapy, e.g. analgesia.

[0163] In certain embodiments, this disclosure relates to pharmaceutical compositions comprising compounds 2-(4-(fluoro- 18F)-2-methylphenoxy)-N-(l -(methoxymethyl)-2-oxo- 1,2-dihydro pyridin-4-yl)-4-(trifluoromethyl) benzamide (Compound B) and 2-(4-(fluoro- 18F)-2-methylphenoxy)-N-(2-hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide (Compound C) or salt thereof or salts thereof or a precursor compound disclosed herein such as such as N-(l-(methoxymethyl)-2-oxo-l,2-dihydropyridin-4-yl)-2-(2-methyl-4-(4, 4,5,5- tetramethyl-1 ,3,2-dioxaborolan-2-yl)phenoxy)-4-(trifluoromethyl)benzamide (Compound A), or salt thereof or and a pharmaceutically acceptable excipient.

[0164] In certain embodiments, the disclosure relates to a pharmaceutical composition comprising a compound as described herein including salts thereof and a pharmaceutically acceptable excipient, diluent, or carrier. In certain embodiments, the pharmaceutical composition is in the form of a powder, liquid, or aqueous buffered solution. In certain embodiments, the buffered solution is a citrate buffered solution, isotonic solution, sterile solution, pyrogen free solution, endotoxins and exotoxins free solution, lipopolysaccharide free solution, and / or bacterial free solution.

[0165] Methods of Use

[0166] The present disclosure also relates to methods of using radiotracers of the present disclosure, or pharmaceutically acceptable salts thereof, or pharmaceutical compositions thereof.

[0167] Radiotracers of the present disclosure can be detected by a suitable imaging technique, such as PET scanning. As such, the radiotracers of the present disclosure can be used in conjunction with an imaging technique, such as PET, for detecting and / or quantifying the one or more NaVs that the radiotracer binds to (e.g.. for selectively detecting and or quantifying certain NaV isoforms).

[0168] Detection of the radiotracers can be done in vivo or ex vivo. It will be understood that the radiotracers of the present disclosure can also be used for detecting, localizing, or quantifying NaV (e.g., NaV1.7 or NaV1.8) expression and / or activity in tissue, e g., a nerve. The radiotracers disclosed herein can also be used in conjunction with a suitable imaging technique, such as PET, e.g., for identifying sources of pain and / or evaluating response to therapy.

[0169] In certain embodiments, a compound disclosed herein comprising a radionuclide is administered to a subject, and the radionuclide in the subject is used to create an image. The radionuclide can be administered at any suitable dose. The subject can be imaged using anysuitable imaging apparatus or imaging technique, for example an apparatus capable of gathering a magnetic resonance image (MRI). a positron emission tomography (PET) scan, or a computed tomography (CT) scan.

[0170] In certain embodiments, the method comprises administering to a subject (which can be human or animal, for experimental and / or diagnostic purposes) an image-generating amount of a compound (e.g.. radiotracer) of the disclosure, labeled with the appropriate isotope and then measuring the distribution of the compound, e.g., by PET. An imagegenerating amount is an amount which is at least able to provide an image, e.g., in a suitable detector such as a PET scanner, considering the detection sensitivity and noise level of the detector (e.g., scanner, e.g., PET scanner), the age of the isotope, the body size of the subject, and route of administration, among other factors.

[0171] For example, a method of the present disclosure can comprise: i) administering to a subject or sample a radiotracer of the present disclosure (e.g., a radionuclide-containing variant of LTGO-33, LTGO-34, LTGO-OOl, LTGO-305, suzetrigine, or PF-05089771, or a pharmaceutically acceptable salt thereof; a compound of Formula (I). (la), (la-1), (la-2), (II). (Ila). (IIa-1). (IIa-2). (Ill), (Illa). (IV). (IVa), (V). (A), (A1)-(A57). a compound of Table 1, or a pharmaceutically acceptable salt thereof; or a pharmaceutical composition thereof); and ii) imaging the sample or subject with an imaging technique (e.g., PET), e.g., to identify and / or quantify the radiotracer, e.g., after it has bound to aNaV (e.g., NaV1.7 or NaV1.8).

[0172] A method of the present disclosure can comprise: i) imaging a subject or sample with an imaging technique (e.g., PET); ii) administering to the subject or sample a radiotracer of the present disclosure (e.g., a radionuclide-containing variant of LTGO-33, LTGO-34, LTGO-OOl, LTGO-305, suzetrigine. or PF-05089771, or a pharmaceutically acceptable salt thereof; a compound of Formula (I). (la), (la- 1). (Ia-2), (II). (Ila). (Ila- 1). (IIa-2). (Ill), (Illa), (IV), (IVa), (V), (A), (A1)-(A57), a compound of Table 1, or a pharmaceutically acceptable salt thereof; or a pharmaceutical composition thereof); iii) imaging the sample or subject with an imaging technique (e.g., PET); and iv) comparing the image of step i) and the image of step iii), e.g., to identify and / or quantify the radiotracer, e.g., after it has bound to aNaV (e.g., NaV1.7 or NaV1.8) and / or measure or observe changes before and after administration of the radiotracer.

[0173] A method of the present disclosure can comprise i) administering to a subject or sample a compound of Formula (A), Formula (B), Formula (I) (e.g., a compound of Formula (la), (la- 1). or (la-2)), Formula (II) (e.g.. a compound of Formula (e.g., a compound of Formula (Ila), (IIa-1 ), or (IIa-2)), Formula (III) (e.g., a compound of Formula (Illa)), Formula(IV) (e.g., a compound of Formula (IV a)), Formula (A1)-(A57), a compound of Table 1, or a salt thereof (e.g.. a pharmaceutically acceptable salt thereof), or a tautomer thereof; or a pharmaceutical composition thereof); and ii) imaging the sample or subject with an imaging technique (e.g., PET), e.g., to identify and / or quantify the radiotracer, e.g., after it has bound to aNaV (e.g., NaV1.7 or NaV1.8).

[0174] A method of the present disclosure can comprise i) administering to a subject or sample Compound B, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof; or a pharmaceutical composition thereof); and ii) imaging the sample or subject with an imaging technique (e.g., PET), e.g., to identify and / or quantify the radiotracer, e.g., after it has bound to a NaV (e.g., NaV1.7 or NaV1.8).

[0175] A method of the present disclosure can comprise i) administering to a subject or sample Compound C, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof; or a pharmaceutical composition thereof); and ii) imaging the sample or subject with an imaging technique (e.g., PET), e.g., to identify and / or quantify the radiotracer, e.g., after it has bound to a NaV (e.g., NaV1.7 or NaV1.8).

[0176] Radiotracers disclosed herein are radiolabeled NaV1.7 or NaV1.8 binders, which can be used to identify NaV1.7 or NaV1.8, which are surrogate markers for pain, in a sample or subject.

[0177] As such, in some aspects, the present disclosure relates to a method for the detection of a NaV (e.g.. selectively detecting a NaV isoform, e.g., NaV1.7 or NaV1.8) in a sample or subject, comprising administering (e.g., intravenously) to a subject or a sample a radiotracer of the present disclosure. In some embodiments, the method comprises administering to the subject or sample a radiotracer of Formula (I), e.g., Formula (la), (la-1), or (la-2). In some embodiments, the method comprises administering to the subject or sample a radiotracer of Formula (II), e.g., Formula (Ila), (Ila- 1 ), or (Ila- 2). In some embodiments, the method comprises administering to the subject or sample a radiotracer of Formula (III), e.g., Formula (Illa). In some embodiments, the method comprises administering to the subject or sample a radiotracer of Formula (IV), e.g., Formula (IVa). In some embodiments, the method comprises administering to the subject or sample a radiotracer of Formula (V). In some embodiments, the method comprises administering to the subject or sample a radiotracer of Formula (A). In some embodiments, the method comprises administering to the subject or sample a radiotracer of Formula (A1)-(A55). In some embodiments, the method comprises administering to the subject or sample a radiotracer of Formula (A56) or (A57). In someembodiments, the method comprises administering to the subject or sample a radiotracer listed in Table 1. It will be understood that the method can be used in vivo or ex vivo.

[0178] In some aspects, the present disclosure relates to a method for the detection of aNaV (e.g., selectively detecting a NaV isoform, e.g., NaV1.7 or NaV1.8) in a sample or subject, comprising administering (e.g., intravenously) to a subject or a sample a compound of Formula (A). Formula (B). Formula (I) (e.g., a compound of Formula (la), (la- 1), or (la-2)), Formula (II) (e.g., a compound of Formula (e.g., a compound of Formula (Ila), (IIa-1), or (IIa-2)), Formula (III) (e g., a compound of Formula (Illa)), Formula (IV) (e.g., a compound of Formula (IV a)), Formula (A1)-(A57), a compound of Table 1, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof. In some aspects, the present disclosure relates to a method for the detection of a NaV (e.g., selectively detecting a NaV isoform, e.g., NaV1.7 or NaV1.8) in a sample or subject, comprising administering (e.g., intravenously) to a subject or a sample Compound B. In some aspects, the present disclosure relates to a method for the detection of a NaV (e.g., selectively detecting a NaV isoform, e.g., NaV1.7 or NaV1.8) in a sample or subject, comprising administering (e.g., intravenously) to a subject or a sample Compound C. It will be understood that the method can be used in vivo or ex vivo.

[0179] A method for the detection of a NaV (e.g., a specific NaV isoform, e.g., NaV1.7 or NaV 1.8) in a sample or subject can further comprise the use of a suitable imaging technique, such as PET. For example, the method can comprise administering the radiotracer to the sample or subject within eight hours (e g., within 7 hours, 6 hours, 5 hours, 4 hours, 3 hours, 2 hours, 1 hour, 0.5 hours, or about 15-30 minutes) of performing an imaging technique for detecting the radiotracer, e.g., a positron emission tomography (PET) scan. The output of imaging technique can then be used for detecting, quantifying, or localizing the radiotracer after it has bound to the NaV.

[0180] It will be understood that certain NaV isoforms, e.g., NaV1.7 or NaV1.8, are expressed in certain tissues. Since the radiotracers of the present disclosure selectively bind to NaV 1.7 or NaV 1.8, they can be used to selectively image those tissues that express NaV1.7 or NaV1.8, such as sensory or sympathetic nerves.

[0181] As such, the present disclosure further relates to a method for the detection of a tissue (e.g., a tissue that expresses aNaV, e.g., NaV1.7 or NaV1.8) in a sample or subject, comprising administering (e.g., intravenously) to a subject or a sample a radiotracer of the present disclosure. The method may further comprise using a suitable imaging technique, e.g., PET scanning. In some embodiments, the tissue is a nerve. In some embodiments, thetissue is a sensory neuron. In some embodiments, the tissue is a sympathetic neuron. In some embodiments, the tissue is situated in the peripheral nervous system. In some embodiments, the tissue is situated in the central nervous system. In some embodiments, the tissue is situated in the brain (e.g., thalamus, medial amygdala, hypothalamus, axons of the olfactory epithelium). In some embodiments, the tissue is situated in the spinal cord (e.g., dorsal hom). In some embodiments, the tissue is situated in the trigeminal nerve (e.g., trigeminal ganglion). In some embodiments the tissue is situated in the dorsal root ganglion. It will be understood that the method can be used in vivo or ex vivo.

[0182] Methods of the present disclosure can be used for various diagnostic purposes, such as for locating areas of aberrant sodium channel expression or activity, e.g., for the purpose of diagnosing the source of pain and / or quantifying neuronal NaV expression.

[0183] Radiotracers of the present disclosure can be used in a method for diagnosing a NaV- related dysfunction (e.g., aNaV1.7 or NaV 1.8 -related dysfunction). Radiotracers of the present disclosure can be used in a method for mapping aNaV-related dysfunction (e.g., a NaV1.7 or NaV1.8-related dysfunction).

[0184] The present disclosure also relates to detection of NaVs, e.g., neuronal NaVs. e.g., Navi.7 or NaVl .8, for disease diagnosis. Methods of the present disclosure relate to monitoring treatment of a disease or disorder, or imaging a disease or disorder, in a subject (e.g., a disease associated with abnormal expression levels or abnormal activity of a NaV, e.g., NaV1.7 or NaV1.8), comprising: i) imaging the subject with an imaging technique (e.g., PET); ii) administering to the subject a radiotracer of the present disclosure (e.g., a radionuclide-containing variant of LTGO-33, LTGO-34, LTGO-OOl, LTGO-305, suzetrigine, or PF-05089771, or a pharmaceutically acceptable salt thereof; a compound of Formula (I), (la), (la-1). (Ia-2), (II). (Ila), (Ila- 1 ), (IIa-2), (III), (Illa). (IV), (IVa), (V), (A), (A1-A57). a compound of Table 1, or a pharmaceutically acceptable salt thereof); or a pharmaceutical composition thereof; iii) imaging the subject with an imaging technique (e.g., PET); and iv) comparing the image of step i) and the image of step iii).

[0185] Methods of the present disclosure also relate to monitoring treatment of a disease or disorder, or imaging a disease or disorder, in a subject (e.g.. a disease associated with abnormal expression levels or abnormal activity of aNaV, e.g., NaV1.7 or NaV1.8), comprising: i) imaging the subject with an imaging technique (e.g., PET); ii) administering to the subject a compound of Formula (A), Formula (B), Formula (I) (e.g., a compound of Formula (la), (la- 1 ), or (la-2)), Formula (II) (e.g., a compound of Formula (e.g., a compound of Formula (Ila), (IIa-1 ), or (IIa-2)), Formula (III) (e.g., a compound of Formula (Illa)),Formula (IV) (e.g., a compound of Formula (IVa)), Formula (A1)-(A57), a compound of Table 1, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof; or a pharmaceutical composition thereof; iii) imaging the subject with an imaging technique (e.g., PET); and iv) comparing the image of step i) and the image of step iii).

[0186] Methods of the present disclosure also relate to monitoring treatment of a disease or disorder, or imaging a disease or disorder, in a subject (e.g.. a disease associated with abnormal expression levels or abnormal activity of aNaV, e.g., NaV1.7 or NaV1.8), comprising: i) imaging the subject with an imaging technique (e g., PET); ii) administering to the subject Compound B or Compound C, or a salt thereof (e.g, a pharmaceutically acceptable salt thereof) or a tautomer thereof; or a pharmaceutical composition thereof; iii) imaging the subject with an imaging technique (e.g., PET); and iv) comparing the image of step i) and the image of step iii).

[0187] The disease or disorder involved in a method of the present disclosure may be associated with abnormal expression levels of one or more NaV isoforms in a subject, e.g., NaV1.7 or NaV1.8. The disease or disorder may be associated with reduced or increased total expression levels of one or more NaV isoforms in a subject, e.g., NaV 1.7 or NaV 1.8. For example, the disease or disorder, or its treatment, may be associated with increased total expression levels ofNaV1.7 or NaV1.8.

[0188] The disease or disorder may be associated with abnormal activity of one or more NaV isoforms in a subject, e.g., NaV1.7 or NaV1.8. The disease or disorder may be associated with increased or decreased functional activity (e.g., opening frequency) of one or more NaV isoforms in a subject, e.g., NaV1.7 or NaV1.8. For example, the disease or disorder may be associated with increased functional activity of one or more NaV isoforms in a subject, e.g., NaV1.7 or NaV1.8.

[0189] The disease or disorder can be chronic pain, as well as other disorders associated with aberrant NaV expression and / or function, including but not limited to Alzheimer’s Disease, amyotrophic lateral sclerosis (ALS), anxiety, autism, cancer, depression, epilepsy, heart failure, Huntington’s Disease, Parkinson’s Disease, and stroke. The disease or disorder can be a seizure, or disease or disorder that causes seizures. The disease or disorder can be a movement disorder.

[0190] The present disclosure also relates to methods of identification and diagnosis, e.g., of a disease, disorder, or injury, and for identifying the location of or source of pain, e.g., using a radiotracer disclosed herein. Such methods can comprise: i) imaging the subject with an imaging technique (e.g., PET); ii) administering to the subject a radiotracer of the presentdisclosure (e.g., a radionuclide-containing variant of LTGO-33, LTGO-34, LTGO-OOl, LTGO-305, suzetrigine, or PF-05089771, or a pharmaceutically acceptable salt thereof; a compound of Formulae (I), (la), (la-1), (la-2), (II), (Ila), (Ila- 1), (IIa-2), (III), (Illa), (IV), (IVa), (V), (A), (A1)-(A57), a compound of Table 1, or a pharmaceutically acceptable salt thereof); or a pharmaceutical composition thereof; iii) imaging the subject with an imaging technique (e.g., PET); and iv) comparing the image of step i) and the image of step iii). Such methods can compnse: i) imaging the subject with an imaging technique (e.g., PET); ii) administering to the subject a compound of Formula (A), Formula (B), Formula (I) (e.g., a compound of Formula (la), (la-1), or (la-2)), Formula (II) (e.g., a compound of Formula (e.g., a compound of Formula (Ila), (IIa-1 ), or (IIa-2)), Formula (III) (e.g., a compound of Formula (Illa)), Formula (IV) (e.g.. a compound of Formula (IVa)), Formula (A1)-(A57), a compound of Table 1, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof; or a pharmaceutical composition thereof; iii) imaging the subject with an imaging technique (e.g., PET); and iv) comparing the image of step i) and the image of step iii). Such methods can comprise: i) imaging the subject with an imaging technique (e.g., PET); ii) administering to the subject Compound B or Compound C, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof; or a pharmaceutical composition thereof; iii) imaging the subject with an imaging technique (e.g., PET); and iv) comparing the image of step i) and the image of step iii).

[0191] In certain embodiments, this disclosure relates to methods comprising: a) administering a composition comprising the 2-(4-(fluoro- 18F)-2-methylphenoxy)-N-(l - (methoxymethyl)-2-oxo-l,2-dihydropyridin-4-yl)-4-(trifluoromethyl)benzamide (Compound B) and / or 2-(4-(fluoro- 18F)-2 -methylphenoxy )-N-(2 -hydroxy py ridin-4-y l)-4- (trifluoromethyl) benzamide (Compound C) tracer isotopically enriched with fluorine 18 to a subject; and scanning the subject for emissions from an area of the subject.

[0192] In certain embodiments, methods further comprise the step of detecting and / or measuring the emissions and creating an image indicating or highlighting the location of the compound isotopically enriched with fluorine 18 in the subject.

[0193] In certain embodiments, methods comprise the step of detecting, measuring, and / or quantifying the emission providing an emission quantity and optionally correlating the emission measurement / detection / quantity to a concentration of 2-(4-(fluoro-18F)-2- methylphenoxy)-N-( 1 -(methoxy methyl)-2-oxo- 1 ,2-dihydropy ridin-4-yl)-4- (trifluoromethyl)benzamide (Compound B) and / or 2-(4-(fluoro-18F)-2-methylphenoxy)-N-(2-hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide (Compound C) in a tissue or other area.

[0194] A disease or disorder involved in a method disclosed herein may be associated with abnormal expression of SCN9A. A disease or disorder involved in a method disclosed herein may be associated with abnormal expression of SCN10A.

[0195] In certain embodiments, methods further comprise the step of correlating a high, low, or abnormal measurement, quantity, or concentration of a radiotracer of the present disclosure to the existence of a disease or disorder in a subject, which can aid in the diagnosis of a disease or disorder in a subject, e.g., in a subject at risk of associated pain, epilepsy, seizures, movement disorders, central nervous system disease, or neurodegenerative disease.

[0196] For example, in some embodiments, the methods comprises the step of correlating a high, low, or abnormal measurement, quantity, or concentration of a compound of Formula (A), Formula (B), Formula (I) (e.g., a compound of Formula (la), (la- 1 ), or (la- 2)), Formula (II) (e.g., a compound of Formula (e.g., a compound of Formula (Ila), (Ila- 1), or (IIa-2)), Formula (III) (e.g.. a compound of Formula (Illa)), Formula (IV) (e.g., a compound of Formula (IV a)), Formula (A1)-(A57), a compound of Table 1, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof, to the existence of or diagnosis of a subject at risk of associated pain, epilepsy, seizures, movement disorders, central nervous system disease, or neurodegenerative disease.

[0197] For example, in some embodiments, the methods comprises the step of correlating a high, low, or abnormal measurement, quantity, or concentration of 2-(4-(fluoro-l 8F)-2- methylphenoxy)-N-(l -(methoxymethyl)-2-oxo- 1 ,2-dihydropyridin-4-yl)-4-(trifluoromethy l)benzamide (Compound B) and / or 2-(4-(fluoro-18F)-2 -methylphenoxy )-N- (2-hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide (Compound C) to the existence of or diagnosis of a subject at risk of associated pain, epilepsy, seizures, movement disorders, central nervous system disease, or neurodegenerative disease.

[0198] In certain embodiments, the disease or disorder is a neurodegenerative disease or a cognitive disorder. A neurodegenerative disorder can be a disease or condition in which the function of a nervous system of a subject becomes impaired. Examples of neurodegenerative diseases include Alzheimer's disease, Alexander's disease, Alper's disease, amyotrophic lateral sclerosis, ataxia telangiectasia, Batten disease, bovine spongiform encephalopathy (BSE), chronic fatigue syndrome, corticobasal degeneration, Creutzfeldt-Jakob disease, frontotemporal dementia, Gerstmann-Straussler-Scheinker syndrome, Huntington's disease, HIV-associated dementia, Kennedy's disease, Krabbe's disease, Lewy body dementia.Machado-Joseph disease, multiple sclerosis, multiple system atrophy, narcolepsy, neuroborreliosis. Parkinson's disease, Pelizaeus-Merzbacher Disease. Pick's disease, primary lateral sclerosis, Refsum's disease, Sandhoffs disease, Schilder's disease, schizophrenia, spinocerebellar ataxia, spinal muscular atrophy, Steele-Richardson-Olszewski disease, or progressive supranuclear palsy.

[0199] A neurodegenerative disease or cognitive disorder can be, for example, Alzheimer's disease, ataxia. Huntington’s disease, Parkinson’s disease, Parkinsonism, motor neuron disease, multiple system atrophy, progressive supranuclear palsy multiple system atrophy, a neuromuscular disorder, or spasticity.

[0200] In certain embodiments, this disclosure relates to methods of diagnosing and treating a subject in need thereof (e.g., a subject with a pain disorder, neurodegenerative disease, cognitive disorder or condition), comprising administering an effective amount a radiotracer of the present disclosure to the subject; measuring emissions from the subject (e.g., using a PET scanner); comparing the emission to a normal or reference value; and diagnosing the subject with or at risk of a disease or disorder, and optionally, treating the subject by further administering to the subject an effective amount of a therapeutic agent, e.g., a therapeutic agent suitable for treating the disease or disorder the subject is diagnosed with or at risk of.

[0201] For example, in some aspects the present disclosure relates to methods of diagnosing and treating a subject with a pain disorder, neurodegenerative disease, cognitive disorder or condition comprising administering an effective amount of a compound of Formula (A), Formula (B), Formula (I) (e.g., a compound of Formula (la), (Ta- 1 ), or (Ta-2)), Formula (IT) (e.g., a compound of Formula (e.g., a compound of Formula (Ila), (Ila- 1 ), or (IIa-2)), Formula (III) (e.g., a compound of Formula (Illa)), Formula (IV) (e.g., a compound of Formula (IV a)), Formula (A1)-(A57), a compound of Table 1, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof, to a subject in need thereof; measuring18F emissions from the subject; comparing the18F brain emission to a normal or reference value; and diagnosing the subject with or at risk of a disease, or pain disorder, if the emission is lower or higher than normal; and treating the subject by administering to the subject an effective amount of a therapeutic agent directed to a disease or condition reported herein.

[0202] For example, in some aspects the present disclosure relates to methods of diagnosing and treating a subject with a pain disorder, neurodegenerative disease, cognitive disorder or condition comprising administering an effective amount of the 2-(4-(fluoro-18F)-2- methylphenoxy)-N-( 1 -(methoxymethyl)-2-oxo- 1 ,2-dihydropyridin-4-yl)-4-(trifluoromethyl)benzamide (Compound B) and / or 2-(4-(fluoro-18F)-2-methylphenoxy)-N- (2-hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide (Compound C) tracer to a subject in need thereof; measuring18F emissions from the subject; comparing the18F brain emission to a normal or reference value; and diagnosing the subject with or at risk of a disease, or pain disorder, if the emission is lower or higher than normal; and treating the subject by administering to the subject an effective amount of a therapeutic agent directed to a disease or condition reported herein.

[0203] Exemplary imaging techniques that can be used in any method disclosed herein include, but are not limited to, magnetic resonance imaging (MRI), ultrasound imaging, tomographic imaging, positron emission tomography (PET) imaging, computed tomography (CT) (e.g., single-photon emission CT), PET with CT imaging, and PET with MRI. For example, the imaging technique used in a method of the present disclosure can be PET imaging. An exemplary imaging technique that can be used in a method of the present disclosure is Single Photon Emission Computed Tomography (SPECT). One or more imaging techniques can be used in combination (e.g., PET and SPECT) in a method of the present disclosure.

[0204] A preferred imaging technique is positron emission tomography (PET), which refers to an imaging technique that produces an image, e.g., three-dimensional image, by detecting pairs of gamma rays emitted indirectly by a positron-emitting radionuclide tracer. Images of tracer concentration within the area are then constructed by computer analysis. A radioactive tracer is administered to a subject e g., into blood circulation. Typically, there is a waiting period while tracer becomes concentrated in areas of interest; then the subject is placed in the imaging scanner. As the radionuclide undergoes positron emission decay, it emits a positron, an antiparticle of the electron with opposite charge, until it decelerates to a point where it can interact with an electron, producing a pair of (gamma) photons moving in approximately opposite directions. These are detected in a scanning device. The technique typically utilizes simultaneous or coincident detection of the pair of photons moving in approximately opposite direction. Photons that do not arrive in pairs (i.e., within a timing- window) are typically ignored. One t pically localizes the source of the photons along a straight line of coincidence (also called the line of response, or LOR). This data is used to generate an image.

[0205] Methods disclosed herein may be combined with other methods such as single photon emission computed tomography (SPECT) scans, computerized tomography (CT) scans, and MRI. A CT scan combines a series of X-ray images taken from different angles uses computer processing to create cross-sectional images, or slices of the brain, bones, bloodvessels and soft tissues inside a body. These scans or associated data can be used to create computerized images that take place in tissue. A scanner records data, and a computer constructs two- or three-dimensional images.

[0206] Images can be generated by virtue of differences in the spatial distribution of the imaging agents that accumulate at a site. The spatial distribution may be measured using any- imaging apparatus suitable for the imaging agent, for example, a gamma camera, a PET apparatus, a SPECT apparatus, MRS, MRI, or optical imaging apparatus, and the like. The extent of accumulation of the imaging agent may be quantified using known methods for quantifying radioactive emissions. A particularly useful imaging approach employs more than one imaging agent to perform simultaneous studies. Alternatively, the imaging method may be carried out a plurality of times with increasing administered doses.

[0207] In some embodiments, a method disclosed herein comprises performing on a subject or sample that has been administered a radiotracer of the present disclosure an imaging technique, such as a PET scan.

[0208] It should be noted that the amount effective to result in uptake of the tracer compound into a cell, tissue, or organ of interest can depend upon a variety of factors, including for example, the age, body weight, general health, sex, and diet of the host (or subject); the time of administration; the route of administration; the rate of excretion of the specific compound employed; the duration of the treatment; the existence of other drugs used in combination or coincidental with the specific composition employed; and like factors.

[0209] In some embodiments, imaging methods provided by the present disclosure include the use of the radionuclide containing compounds (or radiotracers) of the present disclosure, and / or salts thereof (e.g., pharmaceutically acceptable salts thereof), or tautomers thereof, that can generate at least a 2: 1 target to background ratio of radiation intensify, e.g., about a 5: 1, about a 10: 1 or about a 15: 1 ratio of radiation intensify between target and background. In some embodiments, the radiation intensify of the target tissue is more intense than that of the background. In other embodiments, the present disclosure provides methods where the radiation intensity of the target tissue is less intense than that of the background. Generally, any difference in radiation intensify between the target tissue and the background that is sufficient to allow for identification and visualization of the target tissue is sufficient for use in the methods of the present disclosure.

[0210] The radiotracers of the present disclosure can be used to evaluate or investigate the effects of a test compound. For example, disclosed herein are methods of evaluating the binding of a test compound to a NaV (e.g., NaV1.7 or NaV1.8). For example, the methodcan comprise co-administering a radiotracer of the present disclosure and the test compound to a sample or subject. The method can further comprise performing a suitable imaging technique, e.g., PET, shortly after co-administration of the radiotracer and test compound (e.g., within 8 hours, within 4 hours, within 3 hours, within 2 hours, within 1 hour, within 30 mins, or less). The test compound can be a NaV inhibitor (also referred to herein as a NaV blocker), such as anon-radiolabeled NaV inhibitor.

[0211] For example, a compound of Formula (A). Formula (B), Formula (I) (e.g., a compound of Formula (la), (la-1 ), or (la-2)). Formula (II) (e.g., a compound of Formula (e.g., a compound of Formula (Ila), (IIa-1 ), or (IIa-2)), Formula (III) (e.g., a compound of Formula (Illa)), Formula (IV) (e.g., a compound of Formula (IVa)), Formula (A1)-(A57), a compound of Table 1, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof can be administered with a test compound, to evaluate the effect of the test compound, which can be assayed in real time in vivo using a method in accordance with the present disclosure. The radiotracer of the present disclosure may be used with the test compound reported herein to diagnose, assess, or monitor the progression or treatment of a disease or condition, such as pain, epilepsy, seizures, movement disorders and neurodegenerative disorders.

[0212] For example, 2-(4-(fluoro- 18F)-2-methylphenoxy)-N-(l -(methoxymethyl)-2-oxo- 1 ,2- dihydropyridin-4-yl)-4-(trifluoromethyl)benzamide (Compound B) and / or 2-(4-(fluoro-18F)- 2-methylphenoxy)-N-(2-hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide (Compound C), may be administered with a test compound, to evaluate the effect of the test compound, which can be assayed in real time in vivo using a method in accordance with the present disclosure. The radiotracer of the present disclosure may be used with the test compound reported herein to diagnose, assess, or monitor the progression or treatment of a disease or condition, such as pain, epilepsy, seizures, movement disorders and neurodegenerative disorders.

[0213] Each of the test compound and the radiotracer can be administered intravenously to a subject. Alternatively, the test compound and radiotracer can be administered by different routes (e.g., a route of administration disclosed herein). In some embodiments, the radiotracer is not administered orally. It will be understood that co-administration of each of the test compound and radiotracer means the compounds are administered within a short period of time of each other (e.g., within 10 minutes, within 5 minutes, within 2 minutes, within 1 minute) or are administered simultaneously.

[0214] A test compound can be any variety of organic compounds such as small molecules, proteins, antibodies, nucleobases, nucleobase polymers, and known therapeutic agents or therapeutic candidates.

[0215] In some embodiments, this disclosure relates to methods of administering a radiotracer of the present disclosure in combination with a pain associated drug or a test compound, an epilepsy associated drug or a test compound, a seizure associated drug or a test compound, a movement disorders associated drug or a test compound, a neurodegenerative associated drug or a test compound, a cognitive disorder associated drug or a test compound, or central nervous system disorder associated drug or a test compound to a subject, and imaging, detecting, measuring, or quantifying the PET signal in a sample, tissue, connective tissue, blood, bodily fluid, organ or portion / segment thereof, of the subject in order to evaluate the ability of a test compound and / or drug to bind voltage-gated sodium channel enriched tissue of the subject.

[0216] For example, the method can comprise administering a compound of Formula (A), Formula (B), Formula (I) (e.g., a compound of Formula (la), (la- 1). or (la-2)), Formula (II) (e.g., a compound of Formula (e.g., a compound of Formula (Ila), (IIa-1), or (IIa-2)). Formula (III) (e.g., a compound of Formula (Illa)), Formula (IV) (e.g., a compound of Formula (IV a)), Formula (A1)-(A57), a compound of Table 1, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof, in combination with pain associated drug or a test compound, epilepsy associated drug or a test compound, seizure associated drug or a test compound, movement disorders associated drug or a test compound, neurodegenerative associated drug or a test compound, cognitive disorder associated drug or a test compound, or central nervous system disorder associated drug or a test compound to a subject and imaging, detecting, measuring, or quantifying the PET signal in a sample, tissue, connective tissue, blood, bodily fluid, organ or portion / segment thereof, of the subject in order to evaluate the ability of a test compound and / or drug to bind voltage-gated sodium channel enriched tissue of the subject.

[0217] For example, the method can comprise administering 2-(4-(fluoro-18F)-2- methylphenoxy )-N-( 1 -(methoxymethyl)-2-oxo- 1 ,2-dihydropyridin-4-yl)-4- (trifluoromethyl)benzamide (Compound B) and / or 2-(4-(fluoro-18F)-2-methylphenoxy)-N- (2-hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide (Compound C) tracer in combination with pain associated drug or a test compound, epilepsy associated drug or a test compound, seizure associated drug or a test compound, movement disorders associated drug or a test compound, neurodegenerative associated drug or a test compound, cognitive disorderassociated drug or a test compound, or central nervous system disorder associated drug or a test compound to a subject and imaging, detecting, measuring, or quantifying the PET signal in a sample, tissue, connective tissue, blood, bodily fluid, organ or portion / segment thereof, of the subject in order to evaluate the ability of a test compound and / or drug to bind voltagegated sodium channel enriched tissue of the subject.

[0218] A method of the present disclosure can comprise determining whether a subject is or would likely be responsive to a drug or test compound therapy. In certain embodiments, the drug is a pain reliever or a test compound. In certain embodiments, the subject has, is suspected of having, at risk of, or diagnosed with a pain disorder. In certain embodiments, the drug is acetaminophen, a nonsteroidal anti-inflammatory drug (NSAIDs), aspirin, naproxen, ibuprofen, or an opioid such as codeine, fentanyl, hydrocodone, meperidine, methadone, naloxone, or oxycodone. In certain embodiments, the drug is an epilepsy drug or a test compound, seizure associated drug or a test compound. In certain embodiments, the subject has, is suspected of having, at risk of, or diagnosed with a seizure. In certain embodiments, the drug is lacosamide, pregabalin, gabapentin, carbamazepine, oxcarbazepine. ezogabine, phenytoin, or vigabatrin. In certain embodiments, the drug is a movement disorders associated drug or a test compound. In certain embodiments, the subject has, is suspected of having, at risk of, or diagnosed with a movement disorder. In certain embodiments, the drug is levodopa, dopamine agonist, MAO-B antagonist, COMT-inhibitor. anticholinergic, amantadine, or antidepressants. In certain embodiments, the drug is a neurodegenerative disorder associated drug or a test compound. In certain embodiments, the subject has, is suspected of having, at risk of, or diagnosed with a neurodegenerative disorder. In certain embodiments, the drug is amantadine, apomorphine, donepezil, baclofen, dantrolene, carbidopa, or levodopa. In certain embodiments, the drug is a MAO-B inhibitor, safinamide, selegiline, or rasagiline. In certain embodiments, the drug is a COMT inhibitor such as entacapone, opicapone, and tolcapone. In certain embodiments, the drug is lecanemab, aducanumab, or gantenerumab. Lecanemab and aducanumab are therapeutic antibodies clinically approved for patients with mild cognitive impairment (MCI) or mild dementia due to Alzheimer's disease.

[0219] In certain embodiments, if the imaging, detecting, measuring, or quantifying of the PET signal indicates the radiotracer binds to the NaV or NaV-enriched cell, tissue or organ of the subject that is lower than a normal or reference value absent the test compound, then said imaging, detecting, measuring, or quantifying provides an indication that the test compound or drug is binding, or likely binding, with sufficient affinity, e.g., to be effective as a potentialtherapeutic agent. In certain embodiments, methods further comprise the step of administering an effective amount (e.g., therapeutically effective amount) of the test compound or drug to a subject in need thereof.

[0220] For example, if the imaging, detecting, measuring, or quantifying of the PET signal indicates the compound of Formula (A), Formula (B), Formula (I) (e.g., a compound of Formula (la), (la-1 ), or (la-2)), Formula (II) (e.g., a compound of Formula (e.g., a compound of Formula (Ila), (IIa-1 ), or (IIa-2)), Formula (III) (e.g., a compound of Formula (Illa)), Formula (IV) (e.g., a compound of Formula (IVa)), Formula (A1)-(A57), a compound of Table 1, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof binds to the voltage-gated sodium channel enriched tissue of the subject that is lower than a normal or reference value absent the test compound, then said imaging, detecting, measuring, or quantifying provides an indication that the test compound or targeted drug is binding or likely binding with sufficient affinity in the subject to be effective as a potential therapeutic agent. In certain embodiments, methods further comprise the step of administering an effective amount of the test compound or targeted drug to a subject in need thereof.

[0221] For example, if the imaging, detecting, measuring, or quantify ing of the PET signal indicates the 2-(4-(fluoro- 18F)-2-methylphenoxy)-N-(l -(methoxymethyl)-2-oxo- 1 ,2- dihydropyridin-4-yl)-4-(trifluoromethyl)benzamide (Compound B) and / or 2-(4-(fluoro-18F)- 2-methylphenoxy)-N-(2-hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide (Compound C) tracer binds to the voltage-gated sodium channel enriched tissue of the subject that is lower than a normal or reference value absent the test compound, then said imaging, detecting, measuring, or quantifying provides an indication that the test compound or targeted drug is binding or likely binding with sufficient affinity in the subject to be effective as a potential therapeutic agent. In certain embodiments, methods further comprise the step of administering an effective amount of the test compound or targeted drug to a subject in need thereof.

[0222] In some embodiments, if the imaging, detecting, measuring, or quantifying of the PET signal indicates that the radiotracer binds to the cells or tissue of the subject at normal or expected values when compared to a reference value, that can be an indication that the test compound or drug is not binding, or not binding with sufficient affinity, to be effective as a therapeutic agent. For example, in some embodiments the imaging, detecting, measuring, or quantifying of the PET signal indicates that the compound of Formula (A). Formula (B). Formula (I) (e.g., a compound of Formula (la), (la-1), or (la-2)). Formula (II) (e.g., acompound of Formula (e.g., a compound of Formula (Ila), (IIa-1), or (IIa-2)), Formula (III) (e.g., a compound of Formula (Illa)), Formula (IV) (e.g., a compound of Formula (IVa)), Formula (A1)-(A57), a compound of Table 1, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof binds to the cells or tissue of the subject that is normal when compared to a reference value, which is an indication that the test compound or pain-targeted drug is not binding or not binding with sufficient affinity to in the subject to be effective as a potential therapeutic agent.

[0223] In some embodiments, if the imaging, detecting, measuring, or quantifying of the PET signal indicates that the radiotracer binds to the cells or tissue of the subj ect at normal or expected values when compared to a reference value, that can be an indication that the test compound or drug is not binding, or not binding with sufficient affinity, to be effective as a therapeutic agent. For example, in some embodiments the imaging, detecting, measuring, or quantifying of the PET signal indicates that the 2-(4-(fluoro-18F)-2-methylphenoxy)-N-(l- (methoxymethyl)-2-oxo- 1 ,2-dihy dropyridin-4-yl)-4-(trifluoromethyl)benzamide (C ompound B) and / or 2-(4-(fluoro-l 8F)-2-methylphenoxy)-N-(2-hydroxypyridin-4-yl)-4- (trifluoromethyl) benzamide (Compound C) tracer binds to the cells or tissue of the subject that is normal when compared to a reference value, which is an indication that the test compound or pain-targeted drug is not binding or not binding with sufficient affinity' to in the subject to be effective as a potential therapeutic agent.

[0224] The methods disclosed herein, comprising administration (e.g., intravenous administration) of a radiotracer of the present disclosure may comprise administering a single dose, or multiple doses. In some embodiments, a method comprises administering to a subject a single dose of the radiotracer. In some embodiments, a method comprises administering to a subject more than one dose of the radiotracer (e.g.. 2, 3, 4. or more doses).

[0225] The radiotracers of the present disclosure can be administered in very low doses while still being useful for the diagnostic and analytical methods disclosed herein. For example, a single dose may be several orders of magnitude lower than a dose required to exert a therapeutic effect (e.g., to treat pain). It is an advantage of the radiotracers disclosed herein that they can be used at dosages that are much lower than therapeutic doses typically needed for the non-radiolabeled structural analogs, because side-effects or toxicity are much more likely to be encountered at the therapeutic dose level. For example, non-radiolabeled PF- 05089771 was administered at dosages of 300 mg / day which caused elevated cholesterol in a large number of clinical study subjects (see NCT02215252). An advantage of the radiotracers of the present disclosure, such as the radiotracer that is an analog of PF-05089771, is that the radiotracers can be used at significantly lower doses (e.g., 5-20 micrograms) for the methods disclosed herein, which avoids toxicity that was encountered at therapeutic doses.

[0226] In some embodiments, the compounds of the present disclosure (e.g., radiotracers) are excreted from the subject (or excreted from tissues of the body) quickly, e.g., to prevent prolonged exposure to the radiation of the radiolabeled compound administered to the subject. In a particular embodiment, the radiotracer provided herein can be used on an outpatient basis. Typically, compounds of the present disclosure are eliminated from the body in less than about 24 hours.

[0227] The amount of radiotracer, or pharmaceutical composition, administered in a method of the present disclosure (e.g., for diagnostic purposes) and the duration of the imaging study will depend upon, for example, the radionuclide used to label the agent, the body mass of the patient, the nature and severity of the condition being evaluated and treated, the nature of therapeutic treatments which the patient has undergone, and on the idiosyncratic responses of the patient. Ultimately, the attending physician will decide the amount of imaging agent to administer to each individual patient and the duration of the imaging study.

[0228] In some embodiments, a radiotracer of the present disclosure is administered to provide a total dose of between about 1 mCi and about 30 mCi (e.g., about 1 mCi, about 2 mCi, about 4 mCi, about 6 mCi, about 8 mCi, about 10 mCi, about 15 mCi, about 20 mCi, about 25 mCi, or about 30 mCi). A radiotracer disclosed herein may be administered as a bolus dose, as an infusion, or a combination thereof. For example, a radiotracer disclosed herein may be administered as a bolus dose of between about 1 mCi and about 15 mCi (e.g., about 1 mCi, about 2 mCi, about 3 mCi, about 4 mCi, about 5 mCi, about 6 mCi, about 7 mCi, about 8 mCi, about 9 mCi, about 10 mCi, about 11 mCi, about 12 mCi, about 13 mCi, about 14 mCi, or about 15 mCi), followed by an infused dose of betw een about 1 mCi and about 10 mCi (e.g., about 1 mCi, about 2 mCi, about 3 mCi, about 4 mCi, about 5 mCi, about 6 mCi, about 7 mCi, about 8 mCi, about 9 mCi, or about 10 mCi). It will be understood that the term “mCi” refers to “millicurie,” a unit of radioactivity.

[0229] For example, in a method of the present disclosure the radiotracer can be administered (e.g., intravenously) to a subject or sample at a dose of about 5 micrograms to about 20 micrograms. In a method of the present disclosure the radiotracer can be administered (e.g., intravenously) to a subject or sample in an amount that is sufficient to provide a radioactivity of about 3 mCi (108 MBq) to about 10 mCi (370 MBq), e.g., about 5 mCi (185 MBq).

[0230] In a method disclosed herein, the radiotracer may be administered (e.g., intravenously) within about 8 hours, e.g., within 7 hours, 6 hours. 5 hours, 4 hours. 3 hours, 2 hours, 1 hour, 0.5 hour, or e.g., within 15-120 minutes, prior to use of an imaging technique, such as a PET scan, for detecting the radiotracer (e.g., in vivo or ex vivo).

[0231] In some embodiments of a method disclosed herein, the radiotracer of the present disclosure is injected into the subject, e.g.. through a vein, and a scanner is used to make detailed images of areas inside the body over time where the radioactive material is taken up by the cells, tissue, fluids, or organs (e.g., blood, brain, spinal cord, a muscle, spleen, heart, lung, pancreas, small intestine, large intestine, liver, bone, or combinations thereof). For example, when imaging, the scans for tracking a compound of Formula (A), Formula (B), Formula (I) (e.g., a compound of Formula (la), (la-1). or (la-2)), Formula (II) (e.g., a compound of Formula (e.g., a compound of Formula (Ila), (Ila- 1), or (IIa-2)), Formula (III) (e.g., a compound of Formula (Illa)), Formula (IV) (e.g., a compound of Formula (IVa)), Formula (A1)-(A57), a compound of Table 1, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof are contemplated to show the uptake of this tracer in the blood, brain, spinal cord, a muscle, spleen, heart, lung, pancreas, small intestine, large intestine, liver, bone, or combinations thereof. For example, when imaging, the scans for tracking 2-(4-(fluoro-18F)-2-methylphenoxy)-N-(l-(methoxymethyl)-2-oxo-l,2- dihydropyridin-4-yl)-4-(trifluoromethyl)benzamide (Compound B) and / or 2-(4-(fluoro-18F)- 2-methylphenoxy)-N-(2-hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide (Compound C) are contemplated to show the uptake of this tracer in the blood, brain, spinal cord, a muscle, spleen, heart, lung, pancreas, small intestine, large intestine, liver, bone, or combinations thereof.

[0232] In certain embodiments, this disclosure relates to imaging methods comprising a) administering a radiotracer to a subject; and b) scanning the subject for the emission / positron- emissions. The methods can further comprise the steps of detecting the emissions and creating an image of an area of the subject indicating or highlighting the location of the compound containing the radionuclide in the subject. In certain embodiments, the data associated with the emissions and image are recorded on a non-transitory computer readable medium. In certain embodiments, the area of the subject is the central nervous system, brain, spinal cord, lymph nodes, groin, axilla, neck, lungs, liver, kidney, pancreas, stomach, balder, intestines, circulatory' system, breast, prostate, or gallbladder.

[0233] In certain embodiments, this disclosure relates to imaging methods comprising a) administering a compound of Formula (A), Formula (B), Formula (I) (e.g., a compound ofFormula (la), (la-1 ), or (la-2)), Formula (II) (e.g., a compound of Formula (e.g., a compound of Formula (Ila). (IIa-1). or (IIa-2)), Formula (III) (e.g.. a compound of Formula (Illa)), Formula (IV) (e.g., a compound of Formula (IVa)), Formula (A1)-(A57), a compound of Table 1, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof.to a subject; and b) scanning the subject for the emission / positron-emissions, optionally further comprising the steps of detecting the emissions and creating an image of an area of the subject indicating or highlighting the location of the compound containing the radionuclide in the subject. As above, the data associated with the emissions and image can be recorded on a non-transitory computer readable medium, and the area of the subject can be the central nervous system, brain, spinal cord, lymph nodes, groin, axilla, neck, lungs, liver, kidney, pancreas, stomach, balder, intestines, circulatory system, breast, prostate, or gallbladder.

[0234] In certain embodiments, this disclosure relates to imaging methods comprising a) administering 2-(4-(fluoro-18F)-2-methylphenoxy)-N-(l-(methoxymethyl)-2-oxo-l,2- dihydropyridin-4-yl)-4-(trifluoromethyl)benzamide (Compound B) and / or 2-(4-(fluoro-18F)- 2-methylphenoxy)-N-(2-hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide (Compound C), tracer to a subject; and b) scanning the subject for the emission / positron-emissions, optionally further comprising the steps of detecting the emissions and creating an image of an area of the subject indicating or highlighting the location of the compound containing the radionuclide in the subject. As above, the data associated with the emissions and image can be recorded on anon-transitory computer readable medium, and the area of the subject can be the central nervous system, brain, spinal cord, lymph nodes, groin, axilla, neck, lungs, liver, kidney, pancreas, stomach, balder, intestines, circulatory' system, breast, prostate, or gallbladder.

[0235] In certain embodiments, methods disclosed herein are used to detect, measure, quantify, or assess, a radiotracer concentration in a subject suspected of having, being at risk of, or diagnosed with a pain disorder, epilepsy, seizure, movement disorder, cognitive disorder, or central nervous system disorder. For example, a method can be to detect, measure, quantify, assess, diagnose, or evaluate in a subject a compound of Formula (A), Formula (B), Formula (I) (e.g., a compound of Formula (la), (la- 1), or (la-2)), Formula (II) (e.g., a compound of Formula (e.g., a compound of Formula (Ila), (IIa-1 ), or (IIa-2)), Formula (III) (e.g., a compound of Formula (Illa)), Formula (IV) (e.g., a compound of Formula (IVa)), Formula (A1)-(A57), a compound of Table 1, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof concentration in a subjectsuspected of having, being at risk of, or diagnosed with a pain disorder, epilepsy, seizure, movement disorder, cognitive disorder, or central nervous system disorder. Or. for example, a method can be to detect, measure, quantify, assess, diagnose, or evaluate in a subject the 2-(4- (fluoro- 18F)-2-methylphenoxy)-N-( 1 -(methoxymethyl)-2-oxo- 1 ,2-dihy dropyridin-4-yl)-4- (trifluoromethyl)benzamide (Compound B) and / or 2-(4-(fluoro-18F)-2 -methylphenoxy )-N- (2-hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide (Compound C) tracer concentrations in a subject suspected of having, being at risk of, or diagnosed with a pain disorder, epilepsy, seizure, movement disorder, cognitive disorder, or central nervous system disorder.

[0236] In certain embodiments, the subject is a human subject 2, 12, or 16 years old or older or less than 2, 12, or 16 years old. In certain embodiments, the subject is a human subject 55 or 65 years old or older. In certain embodiments, the subject is an infant, e.g., from one month to two years of age. In certain embodiments, the subject is a human subject such as a child, e.g., from two to twelve years of age. In certain embodiments, the subject is a human subject such as an adolescent, e.g., from twelve to sixteen years of age. In certain embodiments, the subject is a human subject sixteen years of age or older

[0237] In some embodiments, methods of the present disclosure can further comprise a step of recording data (e.g., imaging, detecting, measuring, or quantifying data or diagnostic indications therefrom) on a non-transiloiy computer readable medium. In certain embodiments, methods further comprise the step of reporting the data (e.g., imaging, detecting, measuring, or quantifying data or diagnostic indications therefrom) to a medical professional.

[0238] The present disclosure further relates to evaluating or monitoring the effectiveness of a drug therapy or recombinant therapy comprising administering a drug for treating a disease or disorder disclosed herein, in combination wi th, or sometime after, a radiotracer of the present disclosure, and thereafter imaging, detecting, measuring, or quantifying the radiotracer at a location in the subject. For example, in certain embodiments, this disclosure relates to evaluating or monitoring the effectiveness of a drug therapy or recombinant therapy comprising administering a drug for treating a disease or condition reported herein in combination with, or sometime after, a compound of Formula (A), Formula (B), Formula (I) (e.g., a compound of Formula (la), (la-1), or (la- 2)), Formula (II) (e.g., a compound of Formula (e.g., a compound of Formula (Ila), (Ila- 1), or (IIa-2)), Formula (III) (e.g., a compound of Formula (Illa)), Formula (IV) (e.g., a compound of Formula (IV a)), Formula (A1)-(A57), a compound of Table 1. or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof is administered, and thereafter imaging, detecting, measuring,or quantifying the tracer at a location in the subject. For example, in certain embodiments, this disclosure relates to evaluating or monitoring the effectiveness of a drug therapy or recombinant therapy comprising administering a drug for treating a disease or condition reported herein in combination with, or sometime after, the 2-(4-(fluoro-18F)-2- methylphenoxy)-N-(l-(methoxymethyl)-2-oxo-l,2-dihydropyridin-4-yl)-4- (trifluoromethyl)benzamide (Compound B) and / or 2-(4-(fluoro-18F)-2-methylphenoxy)-N- (2-hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide (Compound C) tracer, and thereafter imaging, detecting, measuring, or quantifying the tracer at a location in the subject.

[0239] Synthetic Methods and Precursors

[0240] It will be understood that the compounds of the present disclosure, including pharmaceutically acceptable salts thereof, can be prepared using known techniques, and can be synthesized according to any of numerous possible synthetic routes. The synthetic methods described below are exemplary.

[0241] The present disclosure further relates to synthetic processes for making the radiotracers disclosed herein. For example, a synthetic process of the present disclosure comprises use of a radionuclide-containing precursor (synthetic intermediate) to provide a radiotracer that can bind to a NaV isoform. It can be advantageous to introduce the radionuclide-containing precursor in a late stage of the synthesis, such as to mitigate the relatively short half-life of the radionuclide (e.g.,18F that has a half-life of 109 minutes) prior to use in a method that involves detecting the radionuclide, e.g., using PET imaging.

[0242] A synthetic method of the present disclosure can involve using an18F source, such as [18F] fluoride. For example, [18F] fluoride can be produced by irradiating water (containing H218O) with protons, resulting in a18O(p,n)18F reaction. The [18F] isotope can then be separated from the water and processed for use in a method of the present disclosure, e.g., for the production of a radiotracer of the present disclosure.

[0243] The [18F] fluoride can be recovered using an ion exchange resin. The recovery can be carried out in two steps (extraction and elution): first the anions (not only fluoride) are separated from the enriched [18O] water and trapped on a resin and then, said anions, including [18F] fluoride, are eluted into a mixture containing water, organic solvents, a base, also called activating agent or phase transfer agent or phase transfer catalyst, such as the complex potassium carbonate-Kryptofix 222™ (K2CO3-K222) or a tetrabutylammonium salt. Kryptofix 222™ is a cyclic crown ether, which binds the potassium ion, preventing the formation of18F -KF. Thus, potassium acts as the counter ion of18F - to enhance itsreactivity - but does not interfere with the synthesis. Typical labeling methods use low water content solutions. An evaporation step may follow the recovery of the [18F] fluoride, e.g.. azeotropic evaporation of acetonitrile or other low boiling temperature organic solvent.

[0244] Another extraction process that can be performed is passing the [18F] aqueous solution on a solid support, e.g., as reported in U.S. Patent 8,641,903, incorporated herein by reference. The solid support is typically loaded with a trapping agent, e.g., compound comprising a quaternary amine that is adsorbed on the solid support and allows the [18F] activity to be trapped because of its positive charge. The solid support can then be flushed with a gas or a neutral solvent to remove or push out most of the residual water. The [18F] can be eluted in an organic solvent or in a mixture of organic solvents, and can then be used in a method of the present disclosure (e.g.. for synthesizing a radiotracer of the present disclosure or labelling of precursor compounds).

[0245] The present disclosure further relates to precursors of radiotracers of the present disclosure, e.g., radiolabeled and non-radiolabeled precursors that may be converted to the radiotracer. The precursors may be used in a synthetic method disclosed herein. The precursor can be a compound comprising a boronic acid pinacol ester (Bpm) group, e.g., a precursor compound comprising an aryl-Bpin group.

[0246] For example, a synthetic process of the present disclosure comprises converting a precursor compound comprising a boronic ester group (e.g., a boronic acid pinacol ester (Bpin)) to a compound comprising a radionuclide (e.g.,18F). In some embodiments, the boronic ester group is covalently attached to an aryl (e.g., phenyl) or heteroaryl group. For example, a synthetic process of the present disclosure comprises contacting a precursor compound comprising a boronic ester group (e.g., a Bpin), e.g., covalently attached to an ary l (e.g., phenyl) or heteroaryl group, with [18F]fluoride and optionally a catalyst, thereby substituting the boronic ester group with an18F atom. Schemes 1-6 belo \?provide exemplary synthetic processes depicting this method.

[0247] Scheme 1: Exemplary7synthesis of a radiotracer of the present disclosure using a Bpin-containing precursor., wherein A represents an aryl or heteroaryl ring of a radiotracer disclosed herein.

[0248] Scheme 2: Exemplary synthesis of a radiotracer of Formula (I) using a Bpin-understood that a chiral precursor can be used to obtain a chiral product. Alternatively, a racemic product could be separated into enantiomers, e.g., using chiral HLPC.

[0249] Scheme 3: Exemplary7synthesis of a radiotracer of Formula (II) using a Bpin

[0250] Scheme 4: Exemplary synthesis of a radiotracer of Formula (III) using a Bpincontaining precursor

[0251] Scheme 5: Exemplary synthesis of a radiotracer of Formula (IV) using a Bpin-

[0252] Scheme 6: Exemplary synthesis of a radiotracer of Formula (V) using a Bpin-

[0253] The18F source can be aqueous [18F]fluoride. a mixture of aqueous18F and tetraethylammonium bromide (TEAB), a mixture of aqueous18F and tetrabutylammonium bromide (TBAB), silver fluoride (AgF), potassium fluoride (KF), cesium fluoride (CsF), F- TEDA-BF4 (Selectfluor), N-fluorobenzenesulfonimide (NFSI), [pyF]OTf, [ChpyF]OTf, [Me3pyF]PFe, a copper fluoride complex, or a combination thereof.

[0254] In certain embodiments, the enriched fluorine 18 negative ion is a fluorine 18 potassium salt bound to a cryptand, e.g., a cryptand disclosed herein.

[0255] In some embodiments, a catalyst is used. The catalyst can be a transition metal catalyst, such as a copper catalyst, e.g., Cu(OTf)2Py4 or (tBuCN)2CuOTf.

[0256] It will be understood that a solvent can be used in a synthetic process of the present disclosure, and the choice of solvent can depend on the reagents or conditions used, among other factors. In some embodiments, the solvent is aqueous. In some embodiments, thesolvent is tetrahydrofuran (THF), dimethylacetamine (DMA), dimethylformamide (DMF), n- butanol (n-BuOH). dioxane, water, acetonitrile (MeCN), or a combination thereof.

[0257] Other reagents, such as acids, bases, buffers, phase-transfer agents / catalysts, ligands, or amide coupling reagents, can also be used in a synthetic process of the present disclosure. For example, hydrochloric acid (e.g., 4M HC1 in dioxane), tetraethyl ammonium bromide (TEAB), cesium carbonate, potassium carbonate, or sodium hydride can be used.

[0258] It will be further understood that heating or cooling can be applied in a synthetic process disclosed herein, e.g., to increase or decrease the rate of reaction, or improve solubility of reagents.

[0259] In certain embodiments, this disclosure relates to method of making a radiotracer (e.g., PET imaging agent), such as 2-(4-(fluoro-18F)-2-methylphenoxy)-N-(l- (methoxymethyl)-2-oxo-l,2-dihydropyridin-4-yl)-4-(trifluoromethyl)benzamide (Compound B) and / or 2-(4-(fluoro-l 8F)-2-methylphenoxy)-N-(2-hydroxypyridin-4-yl)-4- (trifluoromethy l) benzamide (Compound C) tracer, comprising contacting a precursor compound N-(l-(methoxymethyl)-2-oxo-l,2-dihydropyridin-4-yl)-2-(2-methyl-4-(4,4,5,5- tetramethyl-1 ,3,2-dioxaborolan-2-yl)phenoxy)-4-(trifluoromethyl)benzamide (Compound A) with an isotopically enriched fluorine 18 negative ion producing the PET imaging tracer.

[0260] In certain embodiments, this disclosure relates to method of making a radiotracer (e.g., PET imaging agent), such as Formula (la-1) or (la-2), comprising contacting a precursor compound, e.g., either the (R)- or (S)-enantiomer of 2-(2-methyl-4-(4, 4,5,5- tetramethyl-l ,3,2-dioxaborolan-2-yl)phenoxy)-N-(3-(S-methylsulfonimidoyl)phenyl)-5- (trifluoromethyl)nicotinamide), with an isotopicahy enriched fluorine 18 negative ion producing the radiotracer of Formula (la-1) or (la-2).

[0261] Additional methods for the synthesis of radiotracers, and other relevant techniques, have been disclosed in the art. For example, Lu et al. report a copper-mediated 18F- radiosynthesis of a PET tracer on a high-throughput microdroplet platform, Lab Chip (2024), 23(21): 4652-4663; Nadporojskii et al. report automation of copper-mediated 18F- fluorination of aryl pinacol boronates using 4-dimethylaminopyridinium triflate. Molecules, 2024, 29. 3342.

[0262] Kits

[0263] Also encompassed by the present disclosure are kits (e.g., pharmaceutical packs). The kits may comprise a radiotracer or composition disclosed herein and a container (e.g., a blister pack, vial, bottle, ampule, dispenser package, syringe, or other suitable container). Insome embodiments, kits may further include a second container comprising a pharmaceutical excipient, e.g., for dilution or suspension of the radiotracer or composition. In some embodiments, the radiotracer or composition provided in the container, and the second container, are combined to form one unit dosage form, or a multi-unit dosage form.

[0264] A kit of the present disclosure can comprise instructions for use.

[0265] A kit of the present disclosure can comprise a pharmaceutically acceptable excipient disclosed herein. For example, the kit can comprise water and / or ethanol.

[0266] The kit of the present disclosure can comprise a reagent. For example, the kit can comprise H218O.

[0267] The kit can comprise one or more containers. The one or more containers can be sealed from the atmosphere. The sealed containers can prevent exposure of the contents of the container from chemical changes occurring due to the atmosphere, e.g., from exposure to oxygen, humidity, or heat. The sealed containers can also be used to compartmentalize components, and prevent undesired interactions between components within the kit.

[0268] A component of the kit, such as the radiotracer, reagent, precursor, pharmaceutically acceptable excipient, solvent, or the like, can be within a container. For example, a kit of the present disclosure can comprise water, H218O, and / or ethanol that is contained by a container in the kit.

[0269] A kit of the present disclosure can comprise a solid support or filter (e.g., a filter for purifying a compound, precursor, or radiotracer of the present disclosure.

[0270] A kit of the present disclosure can comprise potassium. The potassium can be bound to a cry ptand, such as a cryptand disclosed herein.

[0271] In certain embodiments, this disclosure relates to kits comprising a radiotracer of the present disclosure and instructions for use. In certain embodiments, this disclosure relates to kits comprising a compound of Formula (A), Formula (B), Formula (I) (e.g., a compound of Formula (la), (la-1), or (la-2)), Formula (II) (e.g., a compound of Formula (e.g., a compound of Formula (Ila), (IIa-1), or (IIa-2)), Formula (III) (e.g., a compound of Formula (Illa)), Formula (IV) (e.g.. a compound of Formula (IVa)), Formula (A1)-(A57). a compound of Table 1, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof, and / or a suitable precursor compound for making the same, and instructions for use.

[0272] In certain embodiments, this disclosure relates to kits comprising 2-(4-(fluoro-18F)-2- methylphenoxy)-N-( 1 -(methoxy methyl)-2-oxo- 1 ,2-dihydropy ridin-4-yl)-4- (trifluoromethyl)benzamide (Compound B) and / or 2-(4-(fluoro-18F)-2-methylphenoxy)-N- (2-hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide (Compound C) tracer and / orprecursor compound, e.g., N-(l-(methoxymethyl)-2-oxo-l,2-dihydropyridin-4-yl)-2-(2- methyl-4-(4,4,5,5-tetramethyl-1.3.2-dioxaborolan-2-yl)phenoxy)-4- (trifluoromethyl)benzamide (Compound A) and instructions for use. In certain embodiments, the instructions provide for the activity at the end of synthesis. In certain embodiments, the instructions provide for the half-life of the radionuclide. In certain embodiments, the instructions provide that injection should be used within limited time from the time of the end of synthesis. In certain embodiments, the container is a sealed container such as a septum capped vial.

[0273] In certain embodiments, this disclosure relates to kits comprising a radiotracer of the present disclosure and starting materials to make the radiotracer, and / or a substance for preparing a radionuclide, e.g., in a cyclotron. In certain embodiments, this disclosure relates to kits comprising a precursor suitable to make a compound of Formula (A), Formula (B), Formula (I) (e.g., a compound of Formula (la), (la-1), or (la-2)), Formula (II) (e.g., a compound of Formula (e.g., a compound of Formula (Ila), (IIa-1), or (IIa-2)), Formula (III) (e.g., a compound of Formula (Illa)), Formula (IV) (e.g., a compound of Formula (IVa)), Formula (A1)-(A57), a compound of Table 1, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof, and / or a substance for preparing a radionuclide, e.g., in a cyclotron. In certain embodiments, this disclosure relates to kits comprising the precursor N-(l-(methoxymethyl)-2-oxo-l,2-dihydropyridin-4-yl)-2-(2- methyl-4-(4,4,5,5-tetramethyl-1.3.2-dioxaborolan-2-yl)phenoxy)-4- (trifluoromethyl)benzamide (Compound A) and starting materials to make the radionuclide tracer, and / or a substance for preparing a radionuclide in a cyclotron. In certain embodiments, the kit comprises a container having water, H218O, and / or ethanol in water solution. In certain embodiments, the container is sealed from the atmosphere. In certain embodiments, kits comprise a solid support or filter. In certain embodiments, the filter may be used to purify a radionuclide tracer disclosed herein.

[0274] The radiotracer can be prepared at the location of the subject near the time the subject is exposed to an imaging device (e.g., in the same healthcare facility, clinic, or hospital). In certain embodiments, the disclosure relates to kits comprising a precursor compound disclosed herein, optionally reagents for performing chemical reactions, e.g., as reported here, and a solid support. For example, the kit can comprise a precursor compound suitable to make a compound of Formula (A), Formula (B), Formula (I) (e g., a compound of Formula (la), (la- 1). or (la-2)), Formula (II) (e.g.. a compound of Formula (e.g., a compound of Formula (Ila), (IIa-1 ), or (IIa-2)), Formula (III) (e.g., a compound of Formula (Illa)), Formula(IV) (e.g., a compound of Formula (IV a)), Formula (A1)-(A57), a compound of Table 1, or a salt thereof (e.g.. a pharmaceutically acceptable salt thereof), or a tautomer thereof, optionally reagents for performing chemical reactions as reported here, and a solid support. Or, for example, the kit can comprise the precursor compound N-(l-(methoxymethyl)-2-oxo-l,2- dihydropyridin-4-yl)-2-(2-methyl-4-(4,4,5,5-tetramethyl-l,3,2-dioxaborolan-2-yl)phenoxy)- 4-(trifluoromethyl)benzamide (Compound A), optionally reagents for performing chemical reactions as reported here, and a solid support.

[0275] The solid support of a kit disclosed herein can be any suitable solid support. For example, the kit can be selected from the group of solid phase extraction resins or liquid chromatography resins, e.g., silica (oxide) based or non-silica (metal oxide or polymers) based particles optionally functionalized (e.g.. by organosilanization) with alkyl chains for example C4, C8, Cl 8, C30 or other functional groups, e.g., polar groups (amide, carbamate, and urea) embedded within alkyl chains or branched alkyl groups or polymeric packings.

[0276] In some embodiments, the solid support is selected from the group consisting of solid phase extraction resins and liquid chromatography resins resulting from the copolymerization of divinylbenzene and / or styrene, or by the copolymerization with vinylpyrrolidone, vinylacetate, (methacryloyloxymethyl)naphtalene, 4,4'-bis(maleimido)diphenylmethane, p,p’- dihydroxy diphenylmethane diglycidyl methacrylic ester, p.p'-dihydroxy diphenylpropane diglycidyl methacrylic ester, 2-hydroxyethylmethacrylate (HEMA), 2,2- dimethylaminoethylmethacrylate (DMAEMA), ethylene dimethacrylate glycidyl methacrylate, N-vinyl carbazole, acrylonitrile, vinyl pyridine, N-methyl-N- vinyl acetamide, amino styrene, methacry late, ethacrylate, methyl methacrylate, N-vinyl caprolactam, N- methyl-N-vinyl acetamide.

[0277] In some embodiments, the solid support comprises or is functionalized with or preconditioned with: quaternary ammonium salts, e.g., tetraethylammonium carbonate, tetrabutylammonium carbonate; cryptands, e.g., potassium carbonate cryptands such as [2.2.2] cry ptand N(CH2CH2OCH2CH2OCH2CH2)3N, l,4,10-trioxa-7,13-diaza- cyclopentadecane, 4.7,13,16,21,24-hexaoxa-l,10-diazabicyclo[8.8.8]hexacosane, 4,7,13,16,21-pentaoxa-l,10-diazabicyclo[8.8.5] tricosane, 4,7,13,18-tetraoxa-l,10- diazabicyclo[8.5.5] eicosane, 5,6-benzo-4,7,13,16,21,24-hexaoxa-l,10-diazabicyclo[8.8.8] hexacos-5-ene; crown ethers such as 4'-aminobenzo-15-crown-5, 4'-aminobenzo-15-cro\vn-5, 4'-aminobenzo-15-crown-5 hydrochloride, 4'-aminobenzo-18-crown-6, a'-aminodibenzo-18- crown-6. 2-aminomethyl-15-crown-5, 2-aminomethyl-15-crown-5, 2-aminomethyl- 18- crown-6, 4'-amino-5'-nitrobenzo-15-crown-5, 4'-amino-5'-nitrobenzo-15-crown-5, l-aza-12-crown-4, l-aza-15-crown-5, l-aza-15-crown-5, 1 -aza- 18-cro\\n-6. l-aza-18-crown-6, benzo- 12-crown-4, 5,6-benzo-4,7,13.16,21,24-hexaoxa-l,10-diazabicyclo[8.8.8]hexacos-5-ene. 1- benzyl-l-aza-12-crown-4, bis[ (benzo- 15-crown-5)- 15-yl methyl ] pimelate, 4'-bromobenzo-15- crown-5. 4-tert-butylbenzo- 15-crown-5. 4-tert-butylcyclohexano- 15 -crown-5, 4'- carboxybenzo-15-crown-5; calixarenes such as 4-tert-butylcalix[4] arene, 4-tert- butylcalix[4]arene, 4-tert-butylcalix[4]arene, 4-tert-butylcalix[5] arene, 4-tert- butylcalix[6]arene, 4-tert-butylcalix[6]arene, 4-tert-butylcalix[6] arene, 4-tert- butylcalix[8]arene, 4-tert-butylcalix[8]arene, 4-tert-butylcalix|4|arene-tetraacetic acid tetraethyl ester, 4-tert-butylcalix[4] arene tetraacetic acid tetraethyl ester, 4-tert- butylcalix[4] arene- tetraacetic acid triethyl ester, calix[4] arene, calix[6] arene, calix[8] arene, 4-(chloromethyl)calix[4] arene, 4-isopropylcalix[4]arene, C-methylcalix[4]resorcinarene. C- methyl calix [4] res orcinarene, meso-octamethylcalix(4)pyrrole, 4-sulfocalix[4] arene, 4- sulfocalix[4] arene sodium salt, C-undecylcalix[4]resorcinarene monohydrate, C- undecylcalix[4]resorcinarene monohydrate; cyclodextrins such as a-cyclodextrin, |3- cyclodextrin. y-cyclodextrin. (2,6-di-O-)ethyl-p-cyclodextrin. 6-O-a-D-glucosyl-P- cyclodextrin, heptakis(6-O-t-butyldimethylsilyl-2,3-di-O-acetyl)-P-cyclodextrin, heptakis(2,6-di-O-methyl)-P-cyclodextrin, heptakis(2,3,6-tri-O-acetyl)-P-cyclodextrin, heptakis(2,3,6-tri-O-benzoyl)-P-cyclodextrin, hexakis (6-O-tertbutyl-dimethylsilyl)-a- cyclodextrin, hexakis (2,3,6-tri-O-acetyl)-a-cyclodextrin, hexakis (2,3,6-tri-O-methyl)-a- cyclodextrin. (2-hydroxyethyl)-P-cyclodextrin, 6-O-a-maltosyl-P-cyclodextrin hydrate, methyl-P-cyclodextrin, 6-monodeoxy-6-monoamino-P-cyclodextrin, octakis (6-O-t- butyldimethylsilyl)-y-cyclodextrin, sulfopropyl-P-cyclodextrin, triacetyl-a.-cyclodextrin. triacetyl-P-cyclodextrin; EDTA and derivatives such as ethylenediamine-N,N'-diacetic acid, 2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid, trans- 1,2-diaminocy cl ohexane- N,N,N',N'-tetraacetic acid monohydrate, trans-l,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid monohydrate, l,3-diamino-2-hydroxypropane-N,N,N',N'-tetraacetic acid, 1,2- diaminopropane-N,N,N',N'-tetraacetic acid, l,3-diaminopropane-N,N,N',N'-tetraacetic acid, l,3-diamino-2-propanol-N,N,N'.N'-tetraacetic acid, diethylenetriamine-pentaacetic acid calcium trisodium salt hydrate, N-(2-hydroxyethyl)ethylenediamine triacetic acid tnsodium salt hydrate, N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid; and / or polyethylene glycols (PEG), polyethylene oxides (PEO).

[0278] Growth Mediums and Cell Cultures

[0279] Also disclosed herein are growth mediums and cell cultures. A growth medium or cell culture of the present disclosure can comprise a radiotracer disclosed herein and a biological material, such as a cell, tissue, or organ.

[0280] The cell culture, or growth medium (or media) can refer to a composition that contains components that facilitate cell maintenance and growth through protein biosynthesis, such as vitamins, amino acids, inorganic salts, a buffer, and an energy source or fuel, e.g., acetate, succinate, a saccharide / disaccharide / polysaccharide, medium chain fatty acids, and / or optionally nucleotides. Typical components in a growth medium include, without limitation, amino acids (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine, and others); vitamins such as retinol, carotene, thiamine, riboflavin, niacin, biotin, folate, and ascorbic acid; carbohydrate such as glucose, galactose, fructose, or maltose; inorganic salts such as sodium, calcium, iron, potassium, magnesium, zinc; serum; and buffering agents. Additionally, a growth medium may contain a pH indicator, e.g., phenol red. Components in the growth medium may be derived from blood serum or the growth medium may be serum-free. The growth medium may optionally be supplemented with albumin, lipids, insulin and / or zinc, transferrin or iron, selenium, ascorbic acid, and an antioxidant such as glutathione, 2-mercaptoethanol or 1 -thioglycerol. Other components in a growth medium can include ammonium metavanadate, cupric sulfate, manganous chloride, ethanolamine, or sodium pyruvate.

[0281] A growth medium of the present disclosure can comprise a nerve cell. The nerve cell can comprise aNaV, e.g., NaV 1.7 or NaV1.8. In some embodiments, the growth medium comprises a nerve cell. In some embodiments, the nen e cell comprises NaV 1.7. In some embodiments, the nerve cell comprises NaV 1.8.

[0282] In some embodiments, this disclosure relates to a cell culture or growth medium comprising a compound of Formula (A), Formula (B), Formula (I) (e.g., a compound of Formula (la), (la-1), or (la-2)), Formula (II) (e.g., a compound of Formula (e.g., a compound of Formula (Ila), (IIa-1), or (IIa-2)), Formula (III) (e.g., a compound of Formula (Illa)), Formula (IV) (e.g.. a compound of Formula (IVa)), Formula (A1)-(A57). a compound of Table 1, or a salt thereof (e.g., a pharmaceutically acceptable salt thereof), or a tautomer thereof.

[0283] In some embodiments, this disclosure relates to a cell culture or growth medium comprising the 2-(4-(fluoro-18F)-2-methylphenoxy)-N-(l-(methoxymethyl)-2-oxo-l,2- dihydropyridin-4-yl)-4-(trifluoromethyl)benzamide (Compound B) and / or 2-(4-(fluoro-18F)-2-methylphenoxy)-N-(2-hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide (Compound C) tracer or salt thereof.

[0284] Various suitable growth mediums are known in the art. For example, Minimal Essential Medium (MEM) is a term of art referring to a growth medium that contains calcium chloride, potassium chloride, magnesium sulfate, sodium chloride, sodium phosphate and sodium bicarbonate, essential amino acids, and vitamins: thiamine (vitamin Bl), riboflavin (vitamin B2), nicotinamide (vitamin B3), pantothenic acid (vitamin B5), pyridoxine (vitamin B6), folic acid (vitamin M), choline, and inositol (originally known as vitamin B8). Dulbecco's modified Eagle's medium (DMEM) is a growth medium which contains additional components such as glycine, serine, and ferric nitrate with increased amounts of vitamins, amino acids, and glucose. Animal serum such as fetal bovine serum (FBS) is sometimes added to a growth media as a supplement.

[0285] Definitions

[0286] It is to be understood that this disclosure is not limited to particular embodiments described, and as such may, of course, vary. An "embodiment" of this disclosure refers to an example and infers that the example is not limiting. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

[0287] As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present disclosure. Any recited method can be carried out in the order of events recited or in any other order that is logically possible, unless otherwise specified.

[0288] All publications (e.g., scientific journal articles, patent publications, and the like) cited in this disclosure are incorporated by reference in their entireties. To the extent the material incorporated by reference contradicts or is inconsistent with this specification, the specification will supersede any such material. The citation of any references herein is not an admission that such references are prior art to the present disclosure. Various terms relating to aspects of the description are used throughout the specification and claims. Such terms are to be given their ordinary' meaning in the art unless otherwise indicated. Other specifically defined terms are to be construed in a manner consistent with the definitions provided herein.

[0289] The term “pharmaceutically acceptable salt’' as used herein refers to a salt of the compound prepared with relatively nontoxic acids or bases, depending on the particular substituents found on the respective compound. When compounds of the present disclosure contain relatively acidic functionalities, base addition salts can be obtained by contacting the neutral form of such compounds with a sufficient amount of the desired base, either neat or in a suitable solvent (e.g., an inert solvent). Examples of pharmaceutically acceptable base addition salts include sodium, potassium, calcium, ammonium, organic amino, magnesium salt, or a similar salt. When compounds of the present disclosure contain relatively basic functionalities, acid addition salts can be obtained by contacting the neutral form of such compounds with a sufficient amount of the desired acid, either neat or in a suitable solvent (e.g., an inert solvent). Examples of pharmaceutically acceptable acid addition salts include those derived from inorganic acids like hydrochloric, hydrobromic, nitric, carbonic, monohydrogencarbonic, phosphoric, monohydrogenphosphoric, dihydrogenphosphoric, sulfuric, monohydrogensulfuric, hydriodic, or phosphorous acids and the like, as well as the salts derived from organic acids like acetic (acetate), propionic, isobutyric, maleic, malonic, benzoic, succinic, suberic, fumaric, lactic, mandelic, pamoic (pamoate), phthalic, benzenesulfonic, p-toluenesulfonic, citric, tartaric, methanesulfonic (mesylate), and the like. For example, a pharmaceutically acceptable salt disclosed herein may be a hydrochloride salt. Also included are salts of amino acids such as arginate and the like, and salts of organic acids like glucuronic or galacturonic acids and the like. Certain compounds of the present disclosure can contain both basic and acidic functionalities that allow the compounds to be converted into either base or acid addition salts. These salts may be prepared by methods known to those skilled in the art. Other pharmaceutically acceptable salts know n to those of skill in the art are suitable for pharmaceutical compositions the present disclosure relates to.

[0290] Throughout this disclosure, the terms “comprise,” “comprises,” and “comprising” are used in a non-exclusive sense, except where the context requires otherwise. Likewise, the term “include” and its grammatical variants are intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that can be substituted or added to the listed items.

[0291] The articles “a” and “an” are used herein to refer to one or more than one (e.g., to at least one) of the grammatical object of the article. By way of example, “an element” means one element or more than one element.

[0292] The term “about” when referring to a measurable value such as an amount, a temporal duration, and the like, is meant to encompass variations of ±20% or less, or in some instancesI l l±15% or less, or in some instances ±10% or less, or in some instances ±5% or less, or in some instances ±1% or less, or in some instances ±0. 1% or less, from the specified value, as such variations are appropriate.

[0293] The phrase “and / or” as used herein should be understood to mean “either or both” of the elements so conjoined, e.g., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and / or” should be construed in the same fashion, e.g., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and / or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and / or B,” when used in conjunction with open- ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.

[0294] The term “effective amount” as used herein refers to an amount of a compound, or a pharmaceutical composition, described herein which is sufficient to achieve a desired result under the conditions of administration. For example, an effective amount can refer to the amount of compound that elicits the biological or medicinal response that is being sought in a tissue, system, animal, individual or human by a researcher, veterinarian, medical doctor or other clinician. A skilled clinician can determine appropriate dosing based on a variety of considerations including the severity of the disease or disorder, the subject’s age, weight, general health, and other considerations.

[0295] The term “pharmaceutically acceptable excipient” as used herein refers to a non-toxic material that may be formulated with a compound disclosed herein to provide a pharmaceutical composition. Preferably, the pharmaceutically acceptable excipient is inert and does not interfere with the pharmacological activity of a compound which it is formulated with. Pharmaceutically acceptable excipients useful in the manufacture of the pharmaceutical compositions disclosed herein are any of those well known in the art, and include without limitation, diluents, dispersing agents, granulating agents, surface active agents, emulsifiers, disintegrating agents, binding agents, preservatives, buffering agents, lubricating agents, ion exchangers, salts, electrolytes, waxes, and / or oils. For example, a pharmaceutically acceptable excipient may be alumina, aluminum stearate, lecithin, a serum protein (e.g., human serum albumin), a phosphate, glycine, sorbic acid, potassium sorbate, a glyceride mixture (e.g., saturated vegetable fatty acids), water, protamine sulfate, disodiumhydrogen phosphate, potassium hydrogen phosphate, sodium chloride, a zinc salt, colloidal silica, magnesium trisilicate, polyvinyl pyrrolidone, cellulose or a derivative thereof. polyethylene glycol or a derivative thereof (e.g., PEG-300), sodium carboxymethylcellulose, a polyacrylate, a poly ethylene-poly oxypropylene-block polymer, wool fat, a cyclodextrin (e.g., CAPTISOL®), dimethylacetamide (DMA), a polysorbate (e.g., a TWEEN®, e.g., TWEEN-20®), ethylenediaminetetraacetic acid (EDTA) or a salt thereof, and any combination thereof.

[0296] In certain embodiments, methods disclosed herein may make measurements that are compared to a normal or reference value. As used herein, a “reference value” can be an absolute value; a relative value; an average value; a median value, a mean value, or a value as compared to a particular control or baseline value. A reference value can be based on an individual sample or many samples, such as from patients or normal individuals.

[0297] The term “subject” as used herein refers to any animal, such as any mammal, including but not limited to, humans, non-human primates, rodents, dogs, and the like. Nonhuman primates include chimpanzees, cynomolgus monkeys, spider monkeys, baboons, and macaques (e.g., Rhesus). Rodents include mice, rats, woodchucks, ferrets, rabbits, and hamsters. Domestic and game animals include cows, horses, pigs, deer, bison, buffalo, feline species (e.g., domestic cat), canine species (e.g., dog, fox, wolf), avian species, and fish. In some embodiments, the subject is a mammal (e.g., a human, a rat, or a mouse). The subject can be male or female. The subject may be of any age, including an elderly human subject (e.g., 65 years or older), a human subject that is not elderly (e.g., less than 65 years old), or a human pediatric subject (e.g., 18 years old or less). In preferred aspects, the subject is a human. In certain embodiments, the subject is a human patient, a pregnant mother, infant, child, adult, newborn less than 1 years old, or elderly over 50, 60. or 65 years old

[0298] Throughout this disclosure, various embodiments can be presented in a range format (e.g., from X - Y). It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the present disclosure. Accordingly, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed subranges such as from 1 to 5, from 1 to 4, from 1 to 3, from 2 to 6, from 2 to 4, from 3 to 6, etc., as well as individual numbers within that range, e.g.. 1, 2, 2.8, 3. 3.6, 4, 5. 5.4, and 6. As another example, a range such as 95-99%includes 95%, 96%, 97%, 98%, or 99% and all subranges such as 96-99%, 96-98%, 96-97%, 97-99%, 97-98%, etc. This applies regardless of the breadth of the range.

[0299] Various embodiments of the compounds, pharmaceutical compositions, and methods herein are described in further detail herein, and additional definitions may be provided throughout the specification.

[0300] Chemical Definitions

[0301] The compounds provided herein may exist in one or more particular geometric, optical, enantiomeric, diastereomeric, epimeric, stereoisomeric, tautomeric, conformational, or anomeric forms, including but not limited to: cis- and trans- forms; E- and Z-forms; endo- and exo- forms; R-, S-, and meso-forms; D- and L-forms; d- and 1- forms; (+) and (-) forms; keto-, enol-, and enolate-forms; syn- and anti-forms; synclinal- and anticlinal-forms; a- and (3-forms; axial and equatorial forms; boat-, chair-, twist-, envelope- and half chair-forms; and combinations thereof, hereinafter collectively referred to as “isomers’’ (or “isomeric forms”).

[0302] Compounds described herein may comprise one or more asymmetric centers, and thus can exist in various isomeric forms, e.g., enantiomers and / or diastereomers. For example, the compounds described herein can be in the form of an individual enantiomer, diastereomer, or geometric isomer, or can be in the form of a mixture of stereoisomers, including racemic mixtures and mixtures enriched in one or more stereoisomer. In an embodiment, the stereochemistry depicted in a compound is relative rather than absolute. Isomers can be isolated from mixtures by methods known to those skilled in the art, including chiral high- pressure liquid chromatography (HPLC) and the formation and crystallization of chiral salts; or preferred isomers can be prepared by asymmetric synthesis. This disclosure additionally encompasses compounds described herein as individual isomers substantially free of other isomers, and alternatively, as mixtures of various isomers.

[0303] The term “radionuclide” as used herein refers to an unstable isotope that can undergo radioactive decay, and may be referred to herein as a “radioactive nuclide,” “radioisotope,” or “radioactive isotope.” A radionuclide may be present in a compound of the present disclosure as a substituent. A radionuclide of the present disclosure may be a positron emitter, e.g., a radionuclide wherein a proton is converted to a neutron, thereby releasing a positron and an electron neutrino. Examples of radionuclides include, but are not limited to,nC,13N,15O,18F,34mCl,38K,45Ti,51Mn,52mMn,52Fe,55Co,60Cu,61Cu,62Cu,64Cu,66Ga,67Ga,68Ga,71As,72As,74As,75Br,76Br,82Rb,86Y,89Zr,90Nb,94mTc. "mTc, ”OmIn,11’in, ”8Sb,120I,121I,1221.123I,124I,124I.131I, and2O1T1. A preferred radionuclide of the present disclosure is18F.

[0304] Certain compounds disclosed herein can comprise one or more fluorine (F) atoms. It will be understood that when the isotope of F is unspecified in a compound disclosed herein, the F present in the compound is the most stable and abundant isotope, i.e.,19F. A compound comprising a radioactive18F isotope disclosed herein will be denoted by showing18F in a chemical structure of the compound, or by including [18F] in the chemical name of the compound, or using similar notation.

[0305] A radionuclide tracer of the present disclosure can exclude radioactive primordial nuclides. A radiotracer of the present disclosure can include naturally occurring isotopes that exhibit radioactive decay with an isotope distribution that is enriched, i.e., greater than natural abundance. In certain embodiments, the radionuclide can have a half-life of less than 1 hour. In certain embodiments, the radionuclide can have a half-life of more than 1 hour but less than 24 hours. Radioactive isotopes are named herein using various commonly used combinations of the name or symbol of the element and its mass number (e.g.,18F, F-18, or fluorine-18). Preferred radionuclides are those useful in metabolic studies, reaction kinetic studies, detection, or imaging techniques, such as positron emission tomography (PET) or single-photon emission computed tomography (SPECT), including drug or substrate tissue distribution assays. For example, an18F or1'C-labeled compound may be used for PET or SPECT studies.

[0306] As used herein, the term “alkyl” refers to a radical of a saturated hydrocarbon group. An alkyl group can be a straight chain or a branched chain saturated hydrocarbon group. An alkyl disclosed herein can have 1 to 18 carbon atoms (Ci-Ci8)-alkyl, such as 1 to 12 carbon atoms (Ci-Ci2)-alkyl, or 1 to 6 carbon atoms (Ci-C6)-alkyl. Examples of alkyd groups include methyl, ethyl, propyl, isopropyl, buty l, Ao-butyl, sec-butyl, tert-butyl, pentyl, hexyl, and the like. Throughout this disclosure, abbreviations that are well known in the art to describe various alkyl groups or their derivatives may be used, such as Me (methyl), Et (ethyl), Pr (propyl), Bu (butyl), and the like. Each instance of an alkyl group may7be unsubstituted (an “unsubstituted alkyd”), or substituted (a “substituted alkyl”) w ith one or more substituents, e.g., from 1 to 5 substituents, 1 to 3 substituents, or 1 substituent.

[0307] As used herein, the term “alkenyl” refers to a radical of a straight-chain or branched hydrocarbon group having one or more carbon-carbon double bonds, and no triple bonds. An alkenyl group can have from 2 to 18 carbon atoms, for example, an alkenyl group may have 2 to 8 carbon atoms (C2-Cs)-alkenyl, 2 to 6 carbon atoms (C2-C6)-alkenyl, 2 to 5 carbon atoms (C2-Cs)-alkenyl, 2 to 4 carbon atoms (C2-C4)-alkenyl. or 2 to 3 carbon atoms (C2-C3)-alkenyl. The one or more carbon-carbon double bonds can be internal (such as in 2-butenyl) orterminal (such as in 1-butenyl). Examples of alkenyl groups include ethenyl, 1 -propenyl, 2- propenyl, 1-butenyl, 2-butenyl, butadienyl, pentenyl, pentadienyl, hexenyl, heptenyl, octenyl, octatrienyl, and the like. Each instance of an alkenyl group may be independently optionally substituted, e.g., unsubstituted (an “unsubstituted alkenyl”), or substituted (a “substituted alkenyl”) with one or more substituents, e g., from 1 to 5 substituents, 1 to 3 substituents, or 1 substituent.

[0308] As used herein, the term “alkynyl” refers to a radical of a straight-chain or branched hydrocarbon group having from 2 to 18 carbon atoms, and one or more carbon-carbon triple bonds. The alkynyl group may have 2 to 8 carbon atoms (C2-Cs)-alkynyl, 2 to 6 carbon atoms (C2-Ce)-alkynyl, 2 to 5 carbon atoms (C2-C5)-alkynyl, 2 to 4 carbon atoms (C2-C4)- alkynyl, or 2 to 3 carbon atoms (C2-C?)-alkynyl. The one or more carbon-carbon triple bonds can be internal (such as in 2-butynyl) or terminal (such as in 1-butynyl). Examples of alkynyl groups include ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, and the like. Each instance of an alkynyl group may be unsubstituted (an “unsubstituted alkynyl”), or substituted (a “substituted alkynyl”) with one or more substituents, e.g., from 1 to 5 substituents, 1 to 3 substituents, or 1 substituent.

[0309] As used herein, the term “heteroalkyl” refers to a non-cyclic, stable, straight or branched chain, that comprises at least one carbon atom and at least one heteroatom selected from the group consisting of O, N. P, Si, and S, wherein the nitrogen (N) and sulfur (S) atoms may optionally be oxidized, and the nitrogen heteroatom may optionally be quatemized. A heteroalkyl disclosed herein can have 1 to 18 carbon atoms (Ci-is-heteroalkyl), such as 1 to 12 carbon atoms (Ci-Ci2)-heteroalkyl, or 1 to 6 carbon atoms (Ci-Cel-heteroalkyl. The heteroatom(s) O, N, P, S, and Si may be placed at any position of the heteroalkyl group, including at the terminus. Where “heteroalkyl” is recited in this disclosure together with recitations of specific heteroalkyl groups, such as -(CH2)-C(O)-OH, -NH-CH3, or the like, it will be understood that the terms heteroalkyl and recitations of specific heteroalkyl groups are not redundant or mutually exclusive. Rather, the specific heteroalkyl groups are recited to add clarity. Thus, the term “heteroalkyl” should not be interpreted herein as excluding the specific heteroalkyl groups, such as -(CH2)-C(O)-OH, -NH-CH3, or the like. Each instance of a heteroalkyl group may be unsubstituted (an “unsubstituted heteroalkyl”), or substituted (a “substituted heteroalkyd”) with one or more substituents, e.g., from 1 to 5 substituents, 1 to 3 substituents, or 1 substituent.

[0310] As used herein, the term “haloalkyl” refers to a radical of a saturated or unsaturated hydrocarbon group, that may be straight or branched chain, and that includes at least onehalogen atom (e.g., F, Cl, Br, or I, including all isotopes thereof, e.g.,18F and34mCl). A haloalkyl disclosed herein can have 1 to 18 carbon atoms (Ci-Ci8)-haloalkyl. such as 1 to 6 carbon atoms (Ci-C6)-haloalkyl, or 1 to 4 carbon atoms (Ci-C4)-haloalkyl. The halogen atom(s) may be placed at any position of the haloalkyl group. Exemplar}' haloalky l groups include, but are not limited to: -CFs, -CCh, -CH2-CF3, -CH2-CCI3, -CH2-CI, -CH2-I, - (CH2)-F, - (CH2)2-F, - (CH2)3-F, or -(CH2)4-F. It will be understood that haloalkyl can include a particular isotope of the halogen atom, including unstable isotopes, e.g., haloalkyl may refer to -(CH2)2-18F. Each instance of a haloalky l may be unsubstituted (an “unsubstituted haloalkyl”), or substituted (a “substituted haloalkyl”) with one or more substituents, e.g., from 1 to 5 substituents, 1 to 3 substituents, or 1 substituent.

[0311] As used herein, the term “aryl.” refers to a stable aromatic ring system, that may be monocyclic or polycyclic, of which all the ring atoms are carbon. The aromatic ring system may have, for example, six, ten, or fourteen ring carbon atoms. Examples include phenyl (Ph), naphthyl, anthracyl, and the like, which may be referred to herein as benzene, naphthalene, or anthracene, respectively. Each instance of an aryl group may be unsubstituted (an “unsubstituted aryl”), or substituted (a “substituted aryl”) with one or more substituents. For example, a phenyl may be substituted with 1, 2, 3, 4, or 5 substituents.

[0312] As used herein, the term “heteroaryl” refers to an aryl group that includes one or more ring heteroatoms. For example, a heteroaryl can include a stable 5-, 6-. or 7-membered monocyclic or 7-, 8-. or 9-membered bicyclic aromatic heterocyclic ring which consists of carbon atoms, and one or more heteroatoms independently selected from the group consisting of nitrogen, oxygen and sulfur. The nitrogen atom may be substituted or unsubstituted. Examples of heteroaryl groups include pyrrole, furan, indole, thiophene, thiazole, isothiazole, imidazole, triazole, tetrazole, pyrazole, oxazole, isoxazole, pyridine, pyrazine, pyridazine, pyrimidine, quinoline, isoquinoline, quinoxaline, quinazoline, cinnoline, phthalazine, 1,2,3- triazine, 1,2,4-triazine, 1,3,5-triazine, acridine, and the like.

[0313] As used herein, the term “cycloalky 1” refers to a radical of a cyclic hydrocarbon group having from three to ten carbon atoms and no heteroatoms in the cyclic structure. Cycloalkyl can include cyclobutyl, cyclopropyl, cyclopentyl, cyclohexyl, norbomyl. and the like. The cycloalkyl group can be either monocyclic (“monocyclic cycloalkyl”) or contain a fused, bridged or spiro ring system such as a bicyclic system (“bicyclic cycloalkyl”) and can be saturated or can be partially unsaturated. “Cycloalkyl” also includes ring systems wherein the cycloalkvl ring, as defined above, is fused with one or more aryl groups wherein the point of attachment is on the cycloalkyl ring, and in such instances, the number of carbons continue todesignate the number of carbons in the cycloalkyl ring system. Each instance of a cycloalkyl group may be independently optionally substituted, e.g., unsubstituted (an "unsubsti luted cycloalkyl’’), or substituted (a “substituted cycloalkyl”) with one or more substituents.

[0314] As used herein, the term “heterocyclyl” refers to a radical of a 3- to 10-membered cyclic structure comprising one or more carbon atoms and one or more heteroatoms in the ring or rings (a radical of a heterocyclic ring). The heteroatom may be selected from nitrogen, oxygen, sulfur, boron, phosphorous, and silicon. In heterocyclyl groups that contain one or more nitrogen atoms, the point of attachment can be a carbon or nitrogen atom, as valency permits. A heterocyclyl group can be either monocyclic (“monocyclic heterocyclyl”) or a fused, bridged, or spiro ring system such as a bicyclic system (“bicyclic heterocyclyl”), and can be saturated or can be partially unsaturated. Heterocyclyl bicyclic ring systems can include one or more heteroatoms in one or both rings. Heterocyclyl also includes ring systems wherein the heterocyclyl ring, as defined above, is fused with one or more cycloalkyl groups wherein the point of attachment is either on the cycloalkyl or heterocyclyl ring, or ring systems wherein the heterocyclyl ring, as defined above, is fused with one or more aryl or heteroaryl groups, wherein the point of attachment is on the heterocyclyl ring, and in such instances, the number of ring members continue to designate the number of ring members in the heterocyclyl ring system. Each instance of heterocyclyl may be independently optionally substituted, e.g., unsubstituted (an “unsubstituted heterocyclyl”) or substituted (a “substituted heterocyclyl”) with one or more substituents. Additional reference is made to: Oxford Dictionary of Biochemistry and Molecular Biology, Oxford University Press, Oxford, 1997 as evidence that heterocyclic ring is a term well-established in field of organic chemistry'.

[0315] The terms “alkylene,” “alkenylene,” “alkynylene,” “heteroalkylene,” or “haloalkylene,” alone or as part of another substituent, mean, unless otherwise stated, a divalent radical derived from an alkyl, alkenyl, alkynyl, heteroalkyl, or haloalkyl, respectively. For instance, the term “alkylene,” by itself or as part of another substituent, means, unless otherwise stated, a divalent radical derived from an alkyl. In the case of heteroalkylene groups, heteroatoms can also occupy either or both of the chain termini (e.g., alkyleneoxy, alkylenedioxy, alkyleneamino, alkylenediamino, and the like). No orientation of the group is implied by the direction in which the formula is written. For example, the formula -C(O)OR‘- may represent both -C(O)OR’- and -R’OC(O)-. Each instance of an alkylene, alkenylene, alkynylene, heteroalkylene, and haloalkylene may be unsubstituted or substituted with one or more substituents. Each instance of alkylene, alkenylene, alkynylene, heteroalkylene, and haloalkylene can have 1 to 18 carbon atoms (e.g., (Ci-Cis)-alkylene, suchas 1 to 6 carbon atoms (e.g., (Ci-Ce)-alkylene. Examples of alkylene include methylene, ethylene, propylene, butylene, and the like.

[0316] As used herein, the terms “cycloalkylene,’’ “heterocyclylene,” “arylene,” and “heteroarylene,” alone or as part of another substituent, mean a divalent radical derived from a cycloalkyl, heterocyclyl, aryl, and heteroaryl, respectively. Each instance of a cycloalkylene, heterocyclylene, arylene, or heteroarylene may be unsubstituted or substituted with one or more substituents.

[0317] As used herein, the term “cyano” or “-CN” refer to a substituent having a carbon atom joined to a nitrogen atom by a triple bond, e.g., C=N.

[0318] As used herein, the term “halo” or “halogen” refers to F, Cl, Br. or I, including any isotope thereof, including unstable isotopes, e.g.,18F and34mCl. Generally, unless otherwise specified, “F” in a chemical structure disclosed herein will be understood to depict the fluorine-19 isotope (19F), and “18F” will be understood to refer to the radioactive fluorine-18 isotope.

[0319] As used herein, the term “hydroxy” refers to a group of formula -OH.

[0320] As used herein, the term "leaving group” refers to a molecular fragment of a compound (e.g., a precursor compound) which, upon reaction of the compound with an appropriate reactant, undergoes heterolytic bond cleavage. The leaving group may be an anionic leaving group (i.e., the molecular fragment generated upon the heterolytic bond cleavage is an anionic group). Exemplary anionic leaving groups include, but are not limited to, halo groups (e.g., chloride, bromide, or iodide), sulfonate esters (e.g., tosylate or mesylate, which may be referred to herein as tosyl (Ts) or mesyl (Ms), respectively). The leaving group may be a neutral leaving group (i.e., the molecular fragment generated upon the heterolytic bond cleavage is a neutral group). Exemplary neutral leaving groups include, but are not limited to, water and ammonia.

[0321] As used herein, the term “nitro” refers to a substituent having two oxygen atoms bound to a nitrogen atom, e.g., -NO2.

[0322] As used herein, the term “oxo” refers to an oxygen group which is double bonded to another atom, e.g., carbon. For example, “oxo” refers to the =0 in a carbonyl group (C=O) or the oxygen substituent in -CH2-C(O)-CH3.

[0323] As used herein, the phrase “optionally substituted” means unsubstituted or substituted, and the term “substituted” means that a hydrogen atom is removed and replaced by a substituent. A “substitutable atom” means any atom bound to one or more hydrogen atoms, such as the nitrogen in -NH-, or the carbon in -CH- or -CH2-, that can be substituted byreplacing the one or more hydrogen atoms with a substituent. When substituted, one or more of the groups are "substituents." The molecule may be multiply substituted. In the case of an oxo substituent ("=0"), two hydrogen atoms are replaced. It is to be understood that substitution at a given atom is limited by valency. For example, the term “substituted” may be in reference to a substituted alkyl, substituted alkylene, substituted alkenyl, substituted alkenylene, substituted alkynyl, substituted alkynylene, substituted heteroalkyl, substituted heteroalkylene, substituted heteroalkenyl, substituted heteroalkenylene. substituted heteroalkynyl, substituted heteroalkynylene, substituted haloalkyl, substituted haloalkenyl, substituted cycloalkyl, substituted cycloalkylene, substituted heterocyclyl, substituted heterocyclylene, substituted aryl, substituted ar lene, substituted heteroaryl, substituted heteroarylene, and the like, i.e., an alkyl, alkylene, alkenyl, alkenylene. alkynyl, alkynylene, heteroalkyl, heteroalkylene, heteroalkenyl, heteroalkenylene, heteroalkynyl, heteroalkynylene, haloalkyl, cycloalkyl, cycloalkydene, heterocyclyl, heterocyclylene, aryl, ary lene, heteroary l, heteroarylene moieties, and the like, having substituents replacing one or more hydrogen atoms on one or more carbon atoms or heteroatoms of the moiety. In general, the term substituted means that at least one hydrogen present on a group (e.g., a hydrogen bonded to carbon or nitrogen atom of said group) is replaced with a suitable substituent, such as a substituent described herein, including, but not limited to, radionuclides disclosed herein (e.g.,18F). Substituents can be any suitable substituent including, for example, alkyd (e.g., Ci-Ce alkyl), alkenyl (e.g.. C2-C6 alkenyl), alkynyl (e.g., C2-C6 alkynyl), heteroalkyl (e.g., Ci- Ce heteroalkyd), haloalkyl (e g., Ci-Ce haloalkyl, e.g., -CF3, where the halo can be any isotope, including unstable isotopes, for example a haloalkyl group can be -(CH2)18F, - (CH2)218F, -(CH2)318F, -(CH2)418F, or -(CH2)518F), cycloalkyl (e.g., C3-C8 cycloalkyl, e.g., cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl), heterocyclyl (e.g., C3-C8 heterocyclyl). alkylaryl (e.g., benzyd), aryl (e.g., phenyl), heteroaryl (e.g., pyrrolyl, imidazolyl, quinolinyl, or indolyl), halo (e.g., -F, -Cl, -Br, or -I, including any isotope thereof, including an unstable isotope, e.g.,18F or34mCl), hydroxyl, thio, alkydcarbonyloxy, arylcarbonyloxy, alkoxy (e.g., -OMe, -OEt, or -OBn), alkoxycarbonyloxy, aryloxycarbonyloxy, carboxylate, alkylcarbonyl, arylcarbonyl, alkoxycarbonyl, aminocarbonyl, alkylaminocarbonyl, dialkylaminocarbonyl, alkylthiocarbonyl, alkoxyl, phosphate, phosphonato, phosphinato, amino (including alkylamino, dialkylamino, ar lamino. diarylamino, and alkylarylamino). acylamino (including alkylcarbonylamino, arylcarbonylamino, carbamoyl, and ureido), amidino, imino, sulfhydryl, alkylthio, arylthio, thiocarboxylate, sulfate, sulfinyl, sulfonyl, alkylsulfinyl, sulfonato, sulfamoyl, sulfonamide, oxo, nitro, trifluoromethyl, cyano, azido,alkyl-cycloalkyl, alkyl-heterocyclyl, alkylheteroaryl, -C(O)OH, -C(O)O-alkyl (e.g., -C(O)O- tBu or -C(O)OMe), -C(O)O-heteroalkyl, -C(O)O-alkylaryl, -OC(O)O-alkyl, -OC(O)O- heteroalkyL -OC(O)O-alkylaryL -C(O)NH2, -C(O)NH-alkyL -C(O)NH-heteroalkyl, - C(O)NH-alkylaryl, -NHC(O)O-alkyl (e.g., -NHC(O)OtBu), -NHC(O)O-heteroalkyl, - NHC(O)O-alkylaryl (e.g., -NH-Cbz), -C(O)N(alkyl)2, -C(O)N(alkyl)(heteroalkyl), - C(O)N(heteroalkyl)2, -N(alkyl)C(O)O-alkyl (e.g.. N(Me)C(O)OtBu), -N(alkyl)C(O)O- heteroalkyl, -N(alkyl)C(O)O-alkylaryl, -N(alkyl)C(O)N(alkyl)2. - N(alkyl)C(O)N(alkyl)(heteroalkyl), -N(alkyl)C(O)N(heteroalkyl)2, -N(alkyl)C(O)NH- alkylaiyl, =NH, or =N-alkyl, -NRaRb, -NRaC(=O)Rb, NRaC(=O)NRaNRb, -NRaC(=O)ORb, -NRaSO2Rb, -C(=O)Ra, -C(=O)ORa, -C(=O)NRaRb, -OC(=O)NRaRb, -ORa, -SRa, -SORa, - S(=O)2Ra, -OS(=O)2Raand -S(=O)2ORa. Raand Rbin this context may be the same or different and independently hydrogen, halo, hydroxyl, alkyl, alkoxy, amino, alkylamino, dialkylamino, cycloalkyl (e.g., carbocyclyl, carbocycloalkyl), heterocyclyl (e.g., heterocarbocyclyl, heterocarbocycloalkyl). aryl, arylalkyd, heteroaryl, and heteroarylalkyl. The substituent can be a radionuclide disclosed herein (e.g..18F). Cyclic groups (e.g., cycloalky 1, heterocyclyl, aryl, and heteroaryl) can be substituted at one or more ring positions w ith any suitable substituent, such as one of the substituents listed above.

[0324] As used herein, the term “protecting group” refers to a group that acts to temporarily block a particular functional moiety, e.g., -OH, -SH, or -NH2, so that a reaction can be carried out selectively at another reactive site in a multifunctional compound. It will be appreciated by one of ordinary' skill in the art that the synthetic methods and compounds described herein may utilize a variety' of protecting groups. Protecting groups may be introduced and removed at appropriate stages during the synthesis of a compound using methods that are known to one of ordinary skill in the art. The protecting groups are applied according to standard methods of organic synthesis as described in the literature (Theodora W. Greene and Peter G. M. Wuts (2007) Protecting Groups in Organic Synthesis, 4thedition, John Wiley and Sons, incorporated by reference in its entirety). Exemplary' protecting groups include, but are not limited to, oxygen, sulfur, nitrogen and carbon protecting groups. For example, oxygen protecting groups include, but are not limited to, methyl ethers, substituted methyl ethers (e.g., MOM (methoxy methyl ether), MTM (methylthiomethyl ether), BOM (benzyloxymethyl ether), PMB (p-methoxybenzyl), optionally substituted ethyl ethers, optionally substituted benzyl ethers, silyl ethers (e.g., TMS (trimethylsilyl ether). TES (triethylsilylether). TIPS (triisopropylsilyl ether), TBDMS (t-butyldimethylsilyl ether), tribenzyl silyl ether, TBDPS (t-butyldiphenyl silyl ether), esters (e.g., formate, acetate,benzoate (Bz), trifluoroacetate, dichloroacetate), carbonates, cyclic acetals and ketals. In addition, nitrogen or amino protecting groups include, but are not limited to, carbamates (including methyl, ethyl and substituted ethyl carbamates (e.g., Boc or Troc), amides, cyclic imide derivatives, N-alkyl and N-aryl amines, imine derivatives, and enamine derivatives, fluorenylmethyloxycarbonyl (Fmoc), tert-butyloxy carbonyl (Boc), carboxybenzyl (Cbz), acetamide, trifluoroacetamide, etc. It will be appreciated that the present disclosure is not intended to be limited to these protecting groups; rather, a variety of additional equivalent protecting groups may be utilized according to methods known to one skilled in the art.

[0325] The term “solvate” as used herein refers to forms of a compound that are associated with a solvent, usually by a solvolysis reaction. This physical association may include hydrogen bonding. Conventional solvents include water, methanol, ethanol, acetic acid, dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), diethyl ether, and the like. Compounds of the present disclosure may be prepared, e.g., in crystalline form, and may be solvated. Suitable solvates include pharmaceutically acceptable solvates and further include both stoichiometric solvates and non-stoichiometric solvates. In certain instances, the solvate will be capable of isolation, for example, when one or more solvent molecules are incorporated in the crystal lattice of a crystalline solid. “Solvate” encompasses both solution-phase and isolable solvates. Representative solvates include hydrates, ethanolates, and methanolates.

[0326] The term “hydrate” as used herein refers to a compound which is associated with water. Typically, the number of the water molecules contained in a hydrate of a compound is in a definite ratio to the number of the compound molecules in the hydrate. Therefore, a hydrate of a compound may be represented, for example, by the general formula R’xFbO. wherein R is the compound and wherein x is a number greater than 0. A given compound may form more than one type of hydrate, including, e.g., monohydrates (x is 1), lower hydrates (x is a number greater than 0 and smaller than 1, e.g., hemihydrates (R»0.5H2O)), and polyhydrates (x is a number greater than 1, e.g., dihydrates (R»2H2O) and hexahydrates (R*6H2O)).

[0327] The term “tautomer” as used herein refers to compounds that are interchangeable forms of a particular compound structure, and that vary in the displacement of hydrogen atoms and electrons. Thus, two structures may be in equilibrium through the movement of it electrons and an atom (usually H). For example, enols and ketones are tautomers because they are rapidly interconverted by treatment with either acid or base. Another example of tautomerism is the aci- and nitro- forms of phenylnitromethane that are likewise formed bytreatment with acid or base. Tautomeric forms may be relevant to the attainment of the optimal chemical reactivity and biological activity of a compound of interest.

[0328] As used herein, the term '‘derivative” refers to a structurally similar compound that retains sufficient functional attributes of the identified analogue. The derivative may be structurally similar because it is lacking one or more atoms, is substituted, is a salt, has different hydration / oxidation states, or because one or more atoms within the molecule are switched, such as, but not limited to, replacing a oxygen atom with a sulfur atom, replacing an amino group with a hydroxyl group, replacing a nitrogen with a protonated carbon (CH) in an aromatic ring, replacing a bridging amino group (-NH-) with an oxy group (-O-), replacing a bridging amino group (-NH-) with an thio group (-S-), or vice versa. In certain embodiments, a derivative is an alkyl group substituted with a carbocyclyl. e.g., a propyl or butyl group substituted with corresponding a cyclopropyl or cyclobutyl group. The derivative may be a prodrug. Derivatives may be prepared by any variety of synthetic methods or appropriate adaptations presented in synthetic or organic chemistry textbooks, such as those provide in March's Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, Wiley, 6th Edition (2007) Michael B. Smith or Domino Reactions in Organic Synthesis, Wiley (2006) Lutz F. Tietze hereby incorporated by reference.EXAMPLES

[0329] Example 1. Preparation of exemplary radiotracers- Formulas (la-1) and (la-2)

[0330] A mixture of 2-chloro-5-(trifluoromethyl)pyridine-3-carboxylic acid, (3- aminophenyl)(imino)(methyl)-16-sulfanone hydrochloride, hexafluorophosphate benzotriazole tetramethyl uronium (HBTU), and diisopropylethylamine in organic solvent (e.g., dichloromethane or chloroform) will be stirred at room temperature. The solvent will then be removed, e.g., under a stream of N2. and the residue will be treated with aqueousmethanol (4: 1). The resulting mixture will be sonicated and then stirred at room temperature and resulting precipitate will be collected by filtration, washed with water and dried under vacuum.

[0331] A mixture of the precipitate, 4-[18F]fluoro-2-methylphenol and cesium carbonate in acetonitrile will be stirred until consumption of starting material, and warmed to about 50 °C if necessar ’ to promote completion of the reaction. The solvent will then be removed, e.g., under a stream of nitrogen, and the residue treated with aqueous methanol (4: 1). The resulting mixture will be briefly sonicated and then stirred at room temperature, and the resulting precipitate will be collected by filtration, washed with water and dried under vacuum to give the product. Chiral HPLC will be used to resolve each isomer (la-1 and la-2).

[0332] Example 2. Alternative preparation of exemplary radiotracers- Formulas (la-1) and (la- 2)

[0334] 2-(2-Methyl-4-(4,4,5,5-tetramethyl-l,3,2-dioxaborolan-2-yl)phenoxy)-N-(3-(S- methylsulfonimidoyl)phenyl)-5-(trifluoromethyl)nicotinamide will be converted to exemplary radiotracers of Formula (la- 1) or (la-2) using transition-metal catalyzed fluorination chemistry, such as a method for copper-mediated fluorination of arylboronate esters, using an18F source and a copper catalyst (e.g., (tBuCNhCuOTf) and base (e.g., AgF) in a suitable solvent such as THF. (See, e.g., Fier et al. J. Am. Chem. Soc. (2013) 135(7):2552-2559. which is incorporated herein by reference in its entirety). Chiral HPLC will be used to resolve each isomer (la-1 and la- 2). Alternatively, a chiral precursor (i.e., the (R)- or (S)-enantiomer of 2-(2-methyl-4-(4,4,5,5-tetramethyl-l,3,2-dioxaborolan-2- yl)phenoxy)-N-(3-(S-methylsulfonimidoyl)phenyl)-5-(trifluoromethyl)nicotinamide) will be used as starting material, which can be obtained, e.g., by chiral HPLC resolution of the racemic precursor.

[0335] Precursor Preparation

[0336] Cesium carbonate (36.12 g, 110.82 mmol, 2.5 eq.) and 1 (10 g, 44.32 mmol, 1.0 eq.) were added to a stirred solution of 7 (9.95 g, 53.19 mmol, 1.2 eq.) in acetonitrile, and the mixture reaction was warmed to 80 °C and stirred for 4 hours. The mixture reaction was concentrated and adjusted pH to 2 by HC1 to afford 8 (14.2 g) as off-white solid.

[0337] HATU (7.58 g, 19.94 mmol, 1.5 eq.) and DIPEA (5.15 g, 39.88 mmol, 3.0 eq.) were then added to a stirred solution of 8 (5.0 g, 13.29 mmol, 1.0 eq.) in DMF, followed by the addition of 4, and the mixture reaction was stirred for 3 hours. The mixture was extracted by EA and NaCl(aq.) and the organic layer was concentrated to provide 9 (8.2 g, crude) without further purification.

[0338] PhI(AcO)2 (12.79 g, 39.87 mmol, 3.0 eq.) and NH4OAc (4.91 g, 53.16 mmol, 4.0 eq.) were added to a solution of 9 (8.2 g, 13.29 mmol, 1.0 eq.) in EtOH (30 ml) and stirred overnight at room temperature. The mixture reaction was purified by silica gel column (PE / EA=E 1) to provide 10 (6.5 g) as light-yellow solid.

[0339] Pd(dppf)C12 CH2C12 (155 mg, 0.1 eq.) was then added to a solution of 10 (1.0 g, 1 .0 eq.), B(pin)2 (961 mg, 2 .0 eq), and potassium acetate (650 mg, 3.5 eq), in 1,4-dioxane (20mL), and the mixture was stirred at 80 °C for 16 hours. The mixture was extracted by EA (100 mL) and the organic layer was purified by column chromatography to obtain 11 as aracemic mixture (750 mg). Then the final product 11 was obtained via supercritical fluid chromatography (SFC. Coluumn: DAICELCHIRALPAK®IG, 100*3mm 3 pm; Mobile Phase A: Supercritical CO2; Mobile Phase B: EtOH (0.1% DEA); Flow: 1.5 mL / min; 214 nm). 'H NMR: (400 MHz, DMSO-r / 6) 3 10.98 (s, 1H), 8.63 (d, J= 1.2 Hz, 1H), 8.56 (d, J= 1.2 Hz, 1H), 8.38 (d, J= 4.0 Hz, 1H), 7.93 (t, .7= 8.0 Hz, 1H), 7.70 (d, J= 2.0 Hz, 1H), 7.57- 7.68 (m, 3H), 7.22 (d, J= 8.0 Hz, 1H), 4.23 (s, 1H). 3.06 (d, J= 2.0 Hz, 3H). 2.10 (s, 3H), 1.30 (s, 12H). LCMS: m / z = 576.3 (M+H)+.

[0341] Aqueous [18F]fluoride was trapped on a preconditioned Sep-Pak Accell Plus QMA Carbonate Plus Light Cartridge (Waters, MA, USA), and [18F]fluoride was eluted out with a solution of TEAB (1 mg) in MeCN (1 mb). The reaction mixture was dried three times using acetonitrile (1 mL each) at 110 °C under a N2 atmosphere. Chiral precursor compound 11 (1.5 mg) and Cu(OTf)2Py4 (8 mg) in anhydrous DMA / n-BuOH (0.2 / 0.1 mL) were then added and heated at 120 °C for 15 minutes. The mixture was diluted with H2O (10 mL) and was trapped on a Sep-Pak light C18 cartridge (Waters). The crude product was eluted with acetonitrile (1 mL) into H2O (3 mL), and the mixture was injected into prep-HPLC (Lablogic HPLC, Phenomenex Luna C-18 column [250 x 10 mm, 5 pm], mobile phase 45% CH3CN / 0.1% ammonium formate in water, flow :5 mL / min). The collected fraction was diluted with H2O (40 mL) and passed through another Cl 8 cartridge. Radiotracer Formula (la-1) was eluted with EtOH (0.5 mL). The radiotracer was then formulated in saline for injection in mice (see below).

[0342] Example 3. Preparation of exemplary radiotracer Formula (Illa)

[0343] N-(l-ter / -Butyl-4-(5-chloro-2-hydroxyphenyl)-lH-pyrazol-5-yl)-2,2,2- trifluoroacetamide (prepared according to Preparation 209 disclosed in WO 2010 / 079443) will be added to suspension of sodium hydride in dimethylformamide and stirred for approximately 30 minutes. Then an18F-containing variant of tert-butyl-5-chloro-2.4- difluorophenylsulfonyl(thiazol-4-yl)carbamate (prepared according to a modified version of Preparation 453 disclosed in WO 2010 / 079443 using [18F]-5-chloro-2,4- difluorobenzenesulfonyl chloride (instead of 5-chloro-2,4-difluorobenzenesulfonyl chloride) will be added to the mixture and stirred, with addition of potassium carbonate and or heating to about 55 °C if needed. Upon completion the mixture will be diluted with ethyl acetate and the organic extract will be collected, washed with water and saturated aqueous sodium chloride solution, dried over magnesium sulfate, filtered and concentrated in vacuo.Purification will be carried out by chromatography.

[0344] Example 4. Alternative preparation of exemplary radiotracer Formula (ITIa)

[0345] 4-(2-(3-Amino-lH-pyrazol-4-yl)-4-chlorophenoxy)-5-chloro-2-(4,4,5,5-tetramethyl- l,3,2-dioxaborolan-2-yl)-N-(thiazol-4-yl)benzenesulfonamide will be converted to radiotracer Formula (Illa) using transition-metal catalyzed fluorination chemistry, such as a method for copper-mediated fluorination of arylboronate esters using an18F source and a copper catalyst (e g., (tBuCNhCuOTf) and base (e g., AgF) in a suitable solvent such as THE (See, e.g., Fier et al. J. Am. Chem. Soc. (2013) 135(7):2552-2559, which is incorporated herein by reference in its entirety).

[0346] For example, aqueous [18F]fluoride will be trapped on a preconditioned Sep-Pak Accell Plus QMA Carbonate Plus Light Cartridge (Waters, MA, USA), and [18F]fluoride willbe eluted from the cartridge with a solution of TEAB (1 mg) in MeCN (1 mL), and dried three times using acetonitrile (1 mL each) at 110 °C under a N2 atmosphere. 4-(2-(3-Amino- lH-pyrazol-4-yl)-4-chlorophenoxy)-5-chloro-2-(4,4,5,5-tetramethyl-l,3,2-dioxaborolan-2- yl)-N-(thiazol-4-yl)benzenesulfonamide (1.5 mg) and Cu(OTf)2Py4 (8 mg) in anhydrous DMA / n-BuOH (0.2 / 0.1 mL) will then added and heated at 120 °C for 15 minutes. Then 4M HC1 in dioxane (0. 1 mL) will be added, and heated at 80 °C for 8 minutes. After adjusting pH to 7 with 4 M NaOH solution, the mixture will be diluted with water (10 mL) and trapped on a Sep-Pak light Cl 8 cartridge (Waters). The crude product will be eluted with acetonitrile (1 mL) into water (3 mL), and the mixture ill be purified by prep-HPLC to provide radiotracer Formula (Illa).

[0347] Precursor compound 4-(2-(3-amino-lH-pyrazol-4-yl)-4-chlorophenoxy)-5-chloro-2- (4,4,5,5-tetramethyl-l,3,2-dioxaborolan-2-yl)-N-(thiazol-4-yl)benzenesulfonamide can be prepared according to any suitable route, such as by substitution of an aryl bromide according to the procedures provided in Examples 2 or 6.

[0348] Example 5. Preparation of exemplary radiotracers Formula (IIa-1 and IIa-2)

[0349] 4-((2R,3S,4S,5R)-3-(3-Fluoro-2-methoxy-4-(4,4,5,5-tetramethyl-L3,2-dioxaborolan- 2-yl)phenyl)-4,5-dimethyl-5-(trifluoromethyl)tetrahydrofuran-2-carboxamido)picolinamide will be converted to radiotracer Formula (IIa-2) using transition-metal catalyzed fluorination chemistry, such as a method for copper-mediated fluorination of arylboronate esters using an18F source and a copper catalyst (e.g., (tBuCN)2CuOTf) and base (e.g., AgF) in a suitable solvent such as THF. (See, e.g., Fier et al. J. Am. Chem. Soc. (2013) 135(7):2552-2559, which is incorporated herein by reference in its entirety).

[0350] For example, aqueous [18F]fluoride will be trapped on a preconditioned Sep-Pak Accell Plus QMA Carbonate Plus Light Cartridge (Waters, MA, USA), and [18F]fluoride will be eluted from the cartridge with a solution of TEAB (1 mg) in MeCN (1 mL), and dried three times using acetonitrile (1 mL each) at 110 °C under a N2 atmosphere. 4- ((2R,3S,4S,5R)-3-(3-fluoro-2-methoxy-4-(4,4,5,5-tetramethyl-l,3,2-dioxaborolan-2- yl)phenyl)-4,5-dimethyl-5-(trifluoromethyl)tetrahydrofuran-2-carboxamido)picolinamide (1.5mg) and Cu(OTf)2Py4 (8 mg) in anhydrous DMA / n-BuOH (0.2 / 0. 1 mL) will then added and heated at 120 °C for 15 minutes. Then 4M HC1 in dioxane (0.1 mL) will be added, and heated at 80 °C for 8 minutes. After adjusting pH to 7 with 4 M NaOH solution, the mixture will be diluted with water (10 mL) and trapped on a Sep-Pak light C 18 cartridge (Waters). The crude product will be eluted with acetonitrile (1 mL) into water (3 mL), and the mixture will be purified by prep-HPLC to provide radiotracer Formula (IIa-2).

[0351] Precursor compound 4-((2R,3S,4S,5R)-3-(3-fluoro-2-methoxy-4-(4,4,5,5-tetramethyl- l,3,2-dioxaborolan-2-yl)phenyl)-4,5-dimethyl-5-(trifluoromethyl)tetrahydrofuran-2- carboxamidojpicolinamide can be prepared according to any suitable route, such as by substitution of an ary lbromide according to the procedures provided in Examples 2 or 6.

[0352] To make radiotracer Formula (Ila- 1), the same procedure will be followed but using 4-((2R,3S,4S,5R)-3-(4-fluoro-2-methoxy-3-(4,4,5,5-tetramethyl-l,3,2-dioxaborolan-2- yl)phenyl)-4,5-dimethyl-5-(trifluoromethyl)tetrahydrofuran-2-carboxamido)picolinamide as a precursor, which can be prepared according to any suitable route, such as by substitution of an arylbromide according to the procedures provided in Examples 2 or 6.

[0353] Example 6. Preparation of exemplary radiotracer Compound CSynthesis of precursor compound

[0354] Sodium hydride (552 mg, 0.023 mol) was added to a solution of 4-bromopyridin- 2(lH)-one (2 g, 0.011 mol) in DMF (10 mL) at 0 °C, and the mixture was stirred at room temperature for 30 min. MOMC1 (1.2 g, 0.014 mol) was then added at 0 °C, and the mixture was stirred at room temperature for 1 h. The mixture was then poured into water, extracted with ethyl acetate, washed with brine, dried over sodium sulfate (Na2SO4), concentrated, and purified by flash chromatography (petroleum ether:ethyl acetate, 10: 1) to give 4-bromo-l- (methoxymethyl)pyridin-2(lH)-one (1.15 g, 58%) as a yellow oil.

[0355] Cesium carbonate (4.5 g, 14.56 mmol), 2-fluoro-4-(trifluoromethyl)benzamide (1.2 g, 5.50 mmol), Xantphos (216 mg, 0.97 mmol) and Pd(OAc)2 were added to a solution of 4- bromo-l-(methoxymethyl)pyridin-2(lH)-one (1 g, 4.85 mmol) in dioxane (20 mL) under a nitrogen atmosphere, and the mixture was stirred at 130 °C for 2 h. The mixture was then poured into water, extracted with ethyl acetate, washed with brine, dried over Na2SC>4, concentrated and purified by flash chromatography (petroleum etherethyl acetate, 10: 1) to give 2-fluoro- / V-( l -(methoxy methyl)-2-oxo- 1.2-dihy dropyndin-4-y l)-4- (trifluoromethyl)benzamide (600 mg, 36.9%) as a white solid.

[0356] Potassium carbonate (722 mg, 5.22 mmol) and 4-bromo-2-methylphenol (391 mg, 2.09mmol) were added to a solution of 2-lluoro-X-( 1 -(methoxy methyl)-2-oxo- 1 ,2- dihydropyridin-4-yl)-4-(trifluoromethyl)benzamide (600 mg, 1.74 mmol) in DMF (10 mL), and the mixture was stirred at 80 °C for 2 h. The mixture was poured into water, extracted with ethyl acetate, washed with brine, dried over Na2SO4. concentrated and purified by flash chromatography (petroleum etherethyl acetate, 10: 1) to give 2-(4-bromo-2-methylphenoxy)- A'-( I -(methoxymethyl)-2-oxo- 1 ,2-dihy dropyridin-4-yl)-4-(trifluoromethyl)benzamide (510 mg, 69%) as a white solid.

[0357] KO Ac (57 mg, 0.58 mmol), B2PIN2 (297 mg, 1.17 mmol) and Pd(dppf)Ch (10 mg.0.015 mmol) were added to a solution of 2-(4-bromo-2-methylphenoxy)-A-(l- (methoxymethyl)-2-oxo-l ,2-dihy dropyridin-4-yl)-4-(trifluoromethyl)benzamide (150 mg, 0.29 mmol) in dioxane (2 mL) under N2. The mixture was stirred at 80 °C for 2 h, then poured into water, extracted with ethyl acetate, washed with brine, dried over Na2SO4, concentrated and purified by flash chromatography (petroleum ether: ethyl acetate, 4: 1) to give A-(l-(methoxymethyl)-2-oxo-l,2-dihydropyridin-4-yl)-2-(2-methyl-4-(4, 4,5,5- tetramethyl-l,3,2-dioxaborolan-2-yl)phenoxy)-4-(trifluoromethyl)benzamide (68 mg, 42%) as a white solid. 'H NMR: (400 MHz, CDCh) d 9.67 (d, J= 25.0 Hz, 1H), 8.38 (d, J= 8.3 Hz. 1H), 8.02 (d. J= 5.7 Hz. 1H), 7.77 (s, 1H), 7.68 (d, J= 8.2 Hz, 1H), 7.41 (d, J= 8.2 Hz, 1H), 7.13 (d, J= 1.8 Hz, 1H), 7.02 (dd, J= 5.7, 1.8 Hz, 1H), 6.96 (d, J= 8.1 Hz, 1H), 6.85 (s,1H), 5.41 (d, J= 15.4 Hz, 2H), 3.45 (d, J = 1.7 Hz, 3H), 2.22 (s, 3H), 1.31 (s, 12H). LCMS: m / z = 511.0 (M+H) -MOM.

[0358] Aqueous [18F]fluoride was trapped on a preconditioned Sep-Pak Accell Plus QMA Carbonate Plus Light Cartridge (Waters, MA, USA), and [18F]fluoride was eluted from the cartridge with a solution of TEAB (1 mg) in MeCN (1 mL), and dried three times using acetonitrile (1 mL each) at 110 °C under aN2 atmosphere. A-(l-(Methoxymethyl)-2-oxo-l,2- dihydropyridin-4-yl)-2-(2-methyl-4-(4,4,5,5-tetramethyl-l,3,2-dioxaborolan-2-yl)phenoxy)- 4-(trifluoromethyl)benzamide (1.5 mg) and Cu(OTf)2Py4 (8 mg) in anhydrous DMA / n-BuOH (0.2 / 0.1 mL) were then added and heated at 120 °C for 15 minutes. Then 4M HC1 in dioxane (0.1 mL) was added, heated at 80 °C for 8 minutes. After adjusting pH to 7 with 4 M NaOH solution, the mixture was diluted with water (10 mL) and was trapped on a Sep-Pak light C18 cartridge (Waters). The crude product was eluted with acetonitrile (1 mL) into water (3 mL), and the mixture was injected into pre-HPLC (Lablogic HPLC, Phenomenex Luna C-18 column [250 x 10 mm, 5 pm], mobile phase 30% CH3CN / 0. 1% TEA in water, flow:5 mL / min). The collected fraction was diluted with water (80 mL) and passed through another C18 cartridge. Compound C was eluted with EtOH (0.5 mL).

[0359] Example 7. Synthesis of [19F] Reference Compounds Corresponding toExemplary Radiotracers Formula (la-1) and Compound C

[0360] Reference Compound for Formula (la-1)

[0361] Cesium carbonate (53.8 g, 165.2 mmol, 2.5 eq.) and 1 (10 g, 44.32 mmol, 1.0 eq.) was added to a stirred solution of 2 (10 g, 79.3 mmol, 1.2 eq.) in acetonitrile, and the mixture was warmed to 80 °C and stirred for 4 hours. The mixture reaction was concentrated and adjusted pH to 2 by addition of HC1 to afford 3 (17.9 g) as off-white solid.

[0362] Next. HATU (10.8 g, 28.5 mmol, 1.5 eq.) and DIPEA (7.4 g, 57.0 mmol. 3.0 eq.) were added to a stirred solution of 3 (6.0 g, 19.0 mmol, 1.0 eq.) in DMF, then 4 (2.6 g, 19.0 mmol, 1.0 eq.) was added. The mixture reaction was stirred for 3 hours, and then poured into water and extracted with ethyl acetate. The organic layer was concentrated to provide 5 (9.2 g, crude) without further purification.

[0363] PhI(AcO)2 (20.4 g, 63.2 mmol, 3.0 eq.) and NH4OAc (6.5 g, 84.4 mmol, 4.0 eq.) were added to a solution of 5 (9.2 g, 21.1 mmol, 1.0 eq.) in EtOH (30 ml) and stirred overnight at room temperature. The mixture reaction was purified by silica gel column (PE / EA=1 : 1) to provide a racemic mixture of 6 (8.5 g) as light-yellow solid. Then the final product 6 was obtained via supercritical fluid chromatography (SFC, Coluumn: DAICELCHIRALPAK®IG, 100*3mm 3 pm; Mobile Phase A: Supercritical CO2; Mobile Phase B: EtOH (0.1% DEA); Flow: 1.5 mL / min; 214 nm). 'H NMR: (400 MHz, DMSO-d6) 5 10.96 (s, 1H), 8.66 (d, J = 1.2 Hz, 1H), 8.54 (d, J = 2.4 Hz, 1H), 8.38 (d, J = 2.0 Hz, 1H). 7.93 (d, J = 8.0 Hz, 1H). 7.69 (d. J = 8.0 Hz. 1H), 7.62 (dd, J = 8.0 Hz, 1.6 Hz, 1H), 7.27 (dd, J = 8.0 Hz, 4.8 Hz, 1H), 7.20 (dd, J = 9.2 Hz, 3.2 Hz, 1H), 7.10 (dd, J = 8.4 Hz, 3.2 Hz, 1H), 4.23 (s, 1H), 3.06 (d, J = 1.2 Hz, 3H), 2.10 (s, 3H). LCMS: m / z = 468.2 (M+H)+.

[0365] DIEA (621 mg, 4.80 mmol), HATU (1.37 g, 3.60 mmol) and 2-methoxypyridin-4- amine 2 (360 mg, 2.9 mmol) were added to a solution of 2-fluoro-4-(trifluoromethyl)benzoic acid 1 (500 mg, 2.40 mmol) in DCM (10 mL), and the mixture was stirred at room temperature overnight. TLC showed no SM remaining and LCMS showed the product. The reaction mixture was poured into water, extracted with DCM, washed with brine, dried over NazSCL, concentrated and purified by flash (PE / EA = 6 / 1) to give 2-fluoro-A-(2- methoxypyridin-4-yl)-4-(trifluoromethyl)benzamide (400 mg, 83%) as a yellow oil.

[0366] A solution of 2-fluoro-A-(2-methoxypyridin-4-yl)-4-(trifluoromethyl)benzamide (400 mg, 1.27 mmol) in 33% HBr / HOAc (5 mL) was stirred at 100 °C overnight. TLC showed no SM remaining and LCMS showed the product. The reaction mixture was poured into water and extracted with EA. The organic layer was washed with brine, dried over NazSOi. concentrated and purified by flash (PE / EA = 5 / 1) to give 2-fluoro- / V-(2-oxo-l,2- dihydropyridin-4-yl)-4-(trifluoromethyl)benzamide 4 (60 mg. 68%) as a yellow solid.

[0367] Potassium carbonate K2CO3 (83 mg, 0.60 mmol) and 4-fluoro-2-methylphenol 5 (31 mg, 0.24mmol) were added to a solution of 2-fluoro- / V-(2-oxo-l,2-dihydropyridin-4-yl)-4- (trifluoromethyl)benzamide (60 mg, 0.20 mmol) in DMF (1 mL), and the mixture was stirred at 80 °C for 2 h. TLC showed no SM remained. The reaction mixture was poured into water and extracted with EA. The organic layer was washed with brine, dried over NazSCL, concentrated and purified by flash (PE / EA = 10 / 1) to give 2-(4-fluoro-2-methylphenoxy)- / V- (2-oxo- l,2-dihydropyridin-4-yl)-4-(trifluoromethyl)benzami de (33 mg, 79%) as a white solid.'ll NMR: (400 MHz, CDCh) 3 10.94 (d, J= 288.7 Hz, 2H), 7.83 (d, J= 7.9 Hz, 1H), 7.59 (dd, J= 8.0, 1.7 Hz, 1H), 7.30 (d, J= 7.2 Hz, 1H), 7.22 (dd, J= 9.0, 2.4 Hz, 1H). 7.16 - 7.02 (m, 2H), 6.97 (d, J= 1.6 Hz, 1H), 6.74 (d, J= 2.0 Hz, 1H), 6.38 (dd, J= 7.2, 2.2 Hz, 1H), 2.16 (s, 3H). LCMS: m / z = 407.2 (M+H)+.

[0368] Example 8. Whole body biodistribution of Exemplary Radiotracer Compound C in mice

[0369] Compound C formulated in a saline solution, obtained in Example 6, was injected into the tail vein of 16 CD-I mice at a dose of 1-3 MBq. The mice were divided into four groups (4 per group) and euthanized at different time points after the injection of Compound C (at 5 minutes, 15 minutes. 30 minutes, and 60 minutes post injection). Organs of interests (brain, spleen, heart, lungs, pancreas, stomach, small intestine, kidneys, liver), blood, muscle, and bone were collected and weighed, and then counted by gamma counter. The percentage of injected dose per gram (%ID / g) was calculated as follows: %ID / g = tissue activity / injected dose x 100%. The radioactivity was mainly accumulated in the spleen, heart, lung, pancreas, kidney, and liver. Following an initial high uptake, radioactivity decreased over time in these organs. The kinetics in the small intestine with high radioactivity levels at 60 min post-tracer injection, suggesting excretion via the hepatobiliary pathway. A graph depicting the results of the study is provided in FIG. 4.

[0370] Example 9. Whole body biodistribution of exemplary radiotracer formula (la-1) in mice

[0371] Sixteen CD-I mice were injected with 1-3 MBq of the exemplary radiotracer Formula (la- 1) obtained in Example 2, via the tail vein, and then the mice were divided into four groups (4 mice per group) and euthanized at different time points after the injection (at 5 minutes, 15 minutes, 30 minutes, and 60 minutes post-injection). Organs of interests were collected and weighed and then counted by gamma counter. The percentage of injected dose per gram (%ID / g) was calculated as follows: %ID / g = tissue activity / injected dose x 100%. The radioactivity was mainly accumulated in the heart, lung, pancreas, kidney, and liver. Following an initial high uptake, radioactivity decreased over time in these organs. The kinetics in the liver and small intestine with high radioactivity' levels at 60 min post-tracer injection suggest a hepatobiliary elimination pathway. A graph depicting the results of the study is provided in FIG. 5.

[0372] Example 10. PET imaging in naive mice administered exemplary radiotracer Formula (la-1)

[0373] A PET imaging study was conducted. Mice were anesthetized with 2.0 % (v / v) isoflurane during the scan. A dose of 3.0 MBq of the radiotracer Formula (la- 1 ), obtained in Example 2, was intravenously injected into the tail vein of the mice, and a dynamic scan was acquiring using a PET scanner for 60 minutes. The PET image obtained is provided in FIG. 6.

Claims

What is claimed is:

1. A radiotracer that i s a compound comprising a structure of F ormula (A) :or a pharmaceutically acceptable salt thereof, wherein:W is C or N;X is CH or N;Y is C or N, provided that at least one of X and Y is N;R30is hydrogen, (Ci-C4)-alkyl (e.g., methyl or ethyl), (C3-Cs)-cycloalkyl (C1-C4)- haloalkyl (e.g., CF3). optionally substituted heterocyclyl (e.g., morpholinyl), optionally substituted aryl (e.g.. phenyl), optionally substituted heteroaryl (e.g., imidazolyl), or -NH- heterocyclyl;R1is ar l or heteroar l, wherein the ar l or heteroaryl is optionally substituted with one or more groups selected from the group consisting of a radionuclide, (Ci-C4)-haloalkyl, optionally substituted (Ci-Cs)-alkyl. (C3-Cio)-cycloalkyl, halogen (e.g.. F, Cl, or Br, including unstable isotopes thereof such as18F), heteroaryl, cyano, amino, nitro, aryloxyl, aryl, (Ci-Cs)- alkyloxyl, (Ci-C4)-haloalkyloxyl, sulfanyl, trifluoromethylsulfanyl, and arylalkoxyl (including, e.g.,18F);R2is selected from the group consisting of aryl, heteroaryl, and heterocyclyl, wherein the aryl, heteroaryl, and heterocyclyl are optionally substituted with one or more groups selected from the group consisting of (Ci-C4)-haloalkyl, optionally substituted (Ci-Cs)-alkyl, (C3-Cio)-cycloalkyl, halogen (e.g., F, Cl, or Br, including isotopes thereof such as18F), heteroaryl, cyano, amino, nitro, ary loxyl, ary l, (Ci-C8)-alkyloxyl, (Ci-C4)-haloalkyloxyl, oxo, alkylsulfinyl, alkylsulfonyl, alkyliminosulfanonyl, alkylsulfoxide, sulfonamide, alkylsulfoximinyl, morpholinyl, oxazolyl, -S(O)(NH)-(Ci-C4)-alkyl (e.g., -S(O)(NH)-CH3), and -S(O)(NMe)-(Ci-C4)-alkyl; when Y is C, R3is selected from the group consisting of hydrogen, cyano, halogen (e.g., F, Cl. or Br, including isotopes thereof such as18F), (Ci-C8)-alkyoxyl, (Ci-C4)-haloalkyl (e.g., CF3), (Ci-C4)-haloalkyloxyl, (C -C8)-cycloalkyl, nitro, and haloalkyloxyl; or when Y is N, R3is absent;when W is C, R4is selected from the group consisting of hydrogen, cyano, halogen (e.g., F, Cl. or Br, including isotopes thereof such as18F), (Ci-Cs)-alkyoxyl, (Ci-C4)-haloalkyl (e.g., CF3), (Ci-C4)-haloalkyloxyl, optionally substituted (Ci-C8)-alkyl, (C3-C8)-cycloalkyl, and morpholinyl; or when W is N, R4is absent; orR3and R4together form a (C3-C5)-carbocyclic ring (including carbon atoms to which R3and R4are attached); wherein R3and R4are not both hydrogen; and wherein the compound of Formula (A) comprises at least one radionuclide (e.g.,18F).

2. The radiotracer of claim 1, wherein the compound comprises the structure of Formula(I):or a pharmaceutically acceptable salt thereof, wherein X is a radionuclide (e.g.,18F).

3. The radiotracer of claim 1 or 2, wherein the compound comprises the structure ofFormulaor a pharmaceutically acceptable salt thereof.

4. The radiotracer of claim 1, wherein the compound comprises the structure of Formulaor a pharmaceutically acceptable salt thereof, wherein X is a radionuclide (e.g.,18F).

5. The radiotracer of claim 4, wherein the compound comprises the structure of Formulapharmaceutically acceptable salt thereof.

6. A radiotracer that is a compound comprising a structure of Formula (II):or a pharmaceutically acceptable salt thereof, wherein one of Xaand Xbis a radionuclide(e.g.,18F), and the other of Xaand Xbis a stable F isotope.

7. The radiotracer of claim 4, wherein the compound comprises a structure of Formula(Ila):or a pharmaceutically acceptable salt thereof, wherein one of Xaand Xbis a radionuclide (e.g.,18F), and the other of Xaand Xbis a stable F isotope.

8. The radiotracer of claim 6 or 7, wherein the compound comprises a structure of Formula (IIa-1) or (IIa-2):or a pharmaceutically acceptable salt thereof.

9. A radiotracer comprising a structure of Formula (III):or a pharmaceutically acceptable salt thereof, wherein X is a radionuclide (e.g.,18F).

10. The radiotracer of claim 9, comprising a structure of Formula (Illa):(Illa), or a pharmaceutically acceptable salt thereof.

11. A radiotracer of the present disclosure that comprises a compound with a structure ofFormula (B):or a pharmaceutically acceptable salt thereof, wherein:W is C or N;X is CH or N;Y is C or N;R30is hydrogen, (Ci-C4)-alkyl (e.g., methyl or ethyl), (C3-C8)-cycloalkyl (C1-C4)- haloalkyl (e.g., CF3), optionally substituted heterocyclyl (e.g., morpholinyl), optionally substituted aryl (e.g.. phenyl), optionally substituted heteroaryl (e.g., imidazolyl), or -NH- heterocyclyl;R1is aryl or heteroaryl, wherein the aryl or heteroaryl is optionally substituted with one or more groups selected from the group consisting of a radionuclide, (Ci-C4)-haloalkyl, optionally substituted (Ci-Cs)-alkyl, (C3-C io)-cycloalkyl, halogen (e.g., F, Cl, or Br, including isotopes thereof such as18F), heteroaryl, cyano, amino, nitro, aryloxyl, aryl, (Ci-Cs)- alkyloxyL (Ci-C4)-haloalkyloxyl, sulfanyl, trifluoromethylsulfanyl, and arylalkoxyl (including, e.g.,18F);R2is selected from the group consisting of aryl, heteroaryl, and heterocyclyl, wherein the aryl, heteroaryl, and heterocyclyl are optionally substituted with one or more groups selected from the group consisting of (Ci-C4)-haloalkyl, optionally substituted (Ci-Cs)-alkyl, (C3-Cio)-cycloalkyl, halogen (e.g., F, Cl, or Br, including isotopes thereof such as18F), heteroaryl, cyano, amino, nitro, aryloxyl, and, (Ci-Cs)-alky loxyl, (Ci-C4)-haloalk loxyl, oxo, alkylsulfinyl, alkylsulfonyl, alkyliminosulfanonyl, alkylsulfoxide, sulfonamide, alkylsulfoximinyl, morpholinyl, oxazolyl. -S(O)(NH)-(Ci-C4)-alkyl (e.g., -S(0)(NH)-CH3). and -S(O)(NMe)-(Ci-C4)-alkyl; when Y is C, R3is selected from the group consisting of hydrogen, cyano, halogen (e.g., F, Cl, or Br, including isotopes thereof such as18F), (Ci-Cs)- alkyoxyl, (Ci-C4)-haloalkyl (e.g., CF3), (Ci-C4)-haloalky loxyl, (C3-Cs)-cycloalkyl, nitro, haloalkyloxyl; or when Y is N, R3is absent; when W is C, R4is selected from the group consisting of hydrogen, cyano, halogen (e.g., F, Cl, or Br, including isotopes thereof such as18F), (Ci-C8)-alkyoxyl, (Ci-C4)-haloalkyl(e.g., CF3), (Ci-C4)-haloalkyloxyl, optionally substituted (Ci-Cs)-alkyl, (C3-C8)-cycloalkyl, and morpholinyl; or when W is N. R4is absent; or R3and R4together form a (C3-C5)-carbocyclic ring (including carbon atoms to which R3and R4are attached); optionally, wherein R3and R4are not both hydrogen; wherein the compound comprises at least one radionuclide (e.g.,18F); and with the proviso that, when X is CH and W and Y are each C, then R1is not 4-fluoro- 2-methylphenyl and R2is not a methoxymethyl-substituted pyridinone or a hydroxysubstituted pyridine.

12. The radiotracer of any one of claims 1-11. comprising a specific activity of about 0.2 Ci / pmol or greater, e.g., about 0.4 Ci / pmol, about 0.6 Ci / pmol, about 0.8 Ci / pmol, about 1.0 Ci / pmol, about 1.2 Ci / pmol, about 1.4 Ci / pmol, about 1.6 Ci / pmol, about 1.8 Ci / pmol, about 2.0 Ci / pmol, about 2.2 Ci / pmol, about 2.4 Ci / pmol, about 2.6 Ci / pmol, about 2.8 Ci / pmol, about 3.0 Ci / pmol, about 3.5 Ci / pmol. about 4.0 Ci / pmol. about 4.5 Ci / pmol. about 5.0 Ci / pmol, about 6.0 Ci / pmol, about 7.0 Ci / pmol, about 8.0 Ci / pmol, about 9.0 Ci / pmol, about 10 Ci / pmol, about 12 Ci / pmol, about 14 Ci / pmol, about 16 Ci / pmol, about 18 Ci / pmol, about 20 Ci / pmol, or greater.

13. A pharmaceutical composition comprising a radiotracer of any one of claims 1-12, and optionally one or more pharmaceutically acceptable excipients.

14. The pharmaceutical composition of claim 13, comprising one or more pharmaceutically acceptable excipients, optionally, wherein the one or more pharmaceutically acceptable excipients comprise water, ethanol, or a combination thereof, and optionally, wherein the pharmaceutical composition has a pH of between about 5 and about 8.

15. The pharmaceutical composition of claim 13 or 14, comprising a radiochemical purity of between about 20% and about 100%, e.g., between about 30% and about 100%, between about 40% and about 100%, between about 50% and about 100%, between about 60% and about 100%, between about 70% and about 100%, between about 80% and about 100%, between about 90% and about 100%, between about 95% and about 100%. or between about 98% and about 100%.

16. A method of imaging a subject or sample, comprising administering to a subject or sample a radiotracer of any one of claims 1-12, or a pharmaceutical composition of any one of claims 13-15, and performing an imaging technique (e.g., positron emission tomography (PET)) on the subj ect or sample.

17. The method of claim 16, wherein the method comprises imaging a cell, tissue, organ, or a combination thereof, in the subject or in the sample.

18. The method of claim 12, comprising imaging a voltage-gated sodium channel (NaV), e.g., selectively imaging NaV1.7 or NaV1.8.

19. The method of any one of claims 16-18, wherein the radiotracer or pharmaceutical composition is administered to the sample or subject about 4 hours (e.g., about 3 hours, about 2 hours, or less) prior to performing the imaging technique (e.g., PET) on the subject or sample.

20. The method of any one of claims 16-19, comprising selectively binding NaV1.7 with the radiotracer, and optionally, detecting, quantifying, or localizing the radiotracer after it has selectively bound to NaV1.7.

21. The method of any one of claims 16-19, comprising selectively binding NaV1.8 with the radiotracer, and optionally, detecting, quantifying, or localizing the radiotracer after it has selectively bound to NaV1.8.

22. The method of any one of claims 16-21, wherein the radiotracer or pharmaceutical composition is administered to the subject intravenously.

23. The method of any one of claims 16-22, wherein the radiotracer or pharmaceutical composition is administered in an amount sufficient to provide a radioactivity of about 3 mCi (108 MBq) to about 10 mCi (370 MBq).

24. The method of any one of claims 16-23, wherein the method does not comprise treating a disease or disorder in the subject, e.g., the radiotracer or pharmaceuticalcomposition is administered to the subject in an amount that provides less than a therapeutically effective amount.

25. The method of any one of claims 16-24, wherein the method does not comprise treating pain or providing analgesia to a subject, e.g., wherein the radiotracer or pharmaceutical composition is administered to the subject in an amount that is less than an amount effective to treat pain or provide analgesia to the subject.

26. A method of evaluating the binding of a test compound to aNaV (e.g., NaV1.7 or NaV1.8) in a sample or in a subject, comprising co-administering to the sample or subject (i) a radiotracer of any one of claims 1-12, or a pharmaceutical composition of any one of claims 13-15, and (ii) the test compound, and imaging the subject or sample with an imaging technique (e.g., PET).

27. The method of claim 26, wherein the radiotracer or the pharmaceutical composition, and / or the test compound, are administered intravenously.

28. The method of claim 26 or 27, wherein the radiotracer or pharmaceutical composition, and the test compound are each administered within a period of about 1 hour (e.g., within 30 minutes, within 10 minutes, within 5 minutes, within 2 minutes, within 1 minute) or are administered simultaneously.

29. The method of any one of claims 26-28, wherein the test compound is a nonradiolabeled NaV binder (e.g., a non-radiolabeled NaV 1.7 binder or a non-radiolabeled NaV 1.8 binder).

30. A method of manufacturing a radiotracer of any one of claims 1-11.

31. The method of claim 30, wherein a radionuclide (e.g.,18F) or a precursor compnsing the radionuclide is introduced in a late stage of the manufacture (e g., as a penultimate or final step in a synthesis of the radiotracer).

32. The method of claim 30 or 31, further comprising a step of purifying the radiotracer, e.g., by filtration.

33. A compound:(2-(4-(fluoro-18F)-2-methylphenoxy)-N-(2-hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide; Compound C), or salt thereof.

34. A pharmaceutical composition that comprises the compound of claim 33, and a pharmaceutically acceptable excipient.

35. A compound:(N-(l-(methoxymethyl)-2-oxo-l, 2-dihydropyridin-4-yl)-2-(2-methyl-4-(4, 4,5,5- tetramethy 1- 1 ,3,2-dioxaborolan-2-yl)phenoxy)-4-(trifluoromethy l)benzamide; Compound A), or salt thereof.

36. A compound:(2-(4-(fluoro-18F)-2-methylphenoxy)-N-( 1 -(methoxymethyl)-2-oxo- 1 ,2-dihydropyridin-4- yl)-4- (trifluoromethyl)benzamide; Compound B). or salt thereof.

37. A kit comprising a compound of claim 35 or 36, and optionally, a starting material or substance for preparing a compound of claim 33, and optionally, instructions for use.

38. The kit of claim 37, wherein the kit further comprises water, H218O. and / or ethanol, optionally wherein the water, H218O, and / or ethanol is contained by a container in the kit, and optionally, wherein the container is sealed from the atmosphere.

39. The kit of claim 37 or 38, further comprising a solid support or filter (e.g., a filter for purifying a compound).

40. The kit of any one of claims 37-39, further comprising potassium bound to a cryptand.

41. A method of making a compound comprising:(a) contacting N-(l -(methoxymethyl)-2-oxo- 1 ,2-dihydropyridin-4-yl)-2-(2-methyl- 4-(4,4,5,5-tetramethyl-l,3,2-dioxaborolan-2-yl)phenoxy)-4-(trifluoromethyl)benzamide (Compound A)with a copper complex and an isotopically enriched fluorine-18 negative ion, producing 2-(4-(fluoro-18F)-2-methylphenoxy)-N-( 1 -(methoxymethyl)-2-oxo- 1 ,2- dihydropyridin-4-yl)-4-(trifluoromethyl)benzamide (Compound B); and(b) contacting Compound B with an acid, providing 2-(4-(fluoro-18F)-2- methylphenoxy)-N-(2-hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide (Compound C).

42. A method comprising:(a) administering a composition comprising 2-(4-(fluoro-18F)-2-methylphenoxy)-N- (2-hydroxypyridin-4-yl)-4-(trifluoromethyl)benzamide (Compound C) or salt thereof, isotopically enriched with fluorine-18 to a subject; and(b) scanning the subject for emissions from an area of the subject.

43. The method of claim 42, wherein the emissions are from the interior or exterior of a nerve in the subject, optionally, wherein the nerve comprises a voltage-gated sodium channel (NaV), e.g., NaV 1.8.

44. The method of claim 42 or 43, further comprising a step of detecting the emissions and creating an image indicating or highlighting the location of the compound isotopically enriched with fluorine- 18 in the subject.

45. The method of any one of claims 42-44, further comprising a step of quantifying the emission, providing an emission quantity, and recording the emission quantity on non- transitory computer readable media.

46. The method of claim 45, further comprising correlating the emission quantity to a concentration of Compound C in an area of the subject.

47. The method of claim 45 or 46, further comprising reporting the emission quantity to a medical professional.

48. A growth medium comprising 2-(4-(fluoro-18F)-2-methylphenoxy)-N-(2- hydroxypyridin-4-yl)-4-(trifluoromethyl) benzamide (Compound C) or salt thereof.

49. The growth medium of claim 48 comprising a nerve cell, optionally, wherein the nerve comprises a voltage-gated sodium channel (NaV), e.g.. NaV 1.8.

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