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Non-antigenic toxin-conjugate and fusion protein of internalizing receptor system

Inactive Publication Date: 2005-08-11
IMMUNOMEDICS INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0009] It is therefore an object of the present invention to provide a more effective and less toxic anti-tumor therapy, particularly a therapy for treatment of B-cell malignancies, such as NHL and B-CLL.
[0010] It is another object of the invention to improve the value as antigenic targets of slowly internalizing surface antigens such as the CD20 antigen.
[0011] It is a further object of the invention to overcome the tendency of antibodies bound to the surface of lymphoma cells to dissociate rapidly from the surface of the cells.

Problems solved by technology

It suffers, however, from relatively low expression levels on most B-cell malignancies, and is not widely expressed, e.g., it is expressed on only 30-50% of cases of B-cell lymphocytic leukemia (B-CLL).
A major disadvantage of CD20 is that it is a slowly internalizing antigen.
A further problem of CD20 is the fact that B-cell malignancies exhibit a more rapid dissociation of bound anti-CD20 mAbs from the surface as compared to nonlymphoma tumor cells.
This suggests that a therapy that uses bonding to a B-cell restricted antigen, particularly those characterized by slow internalization, would not be successful.
This severely limits the duration of therapy.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

Determining of Expression of the β / γc Chains of IL-2 / IL-15 by a Malignant Cell Type

[0035] Five B-lymphoma cell lines were assayed for IL-15 and IL-2 binding, along with two non-B cell lines (MLA 144, a T cell line known to express IL-2Rβ / γc and MB-02, an AML derived cell line). 125I-labeled rIL-15 was used. Cold ligand inhibition was done with both IL-2 and IL-15 to allow estimation of the contribution of IL-15Rα to the overall binding.

[0036] Washed cells (2×106) were suspended in binding buffer (growth medium). To these tubes was added either buffer or a 150-fold molar excess of cold rIL-15 or a 500-fold excess of cold rIL-2 for 15 min @ 4° C. Then 125I-IL-15 was added at 1.5 nM final concentration. Binding was allowed to proceed for 90 min @ 4° C. after which cells were transferred to 0.4 ml tubes and spun through a cushion of 80 / 20 dibutyl phthalate / olive oil. The tips were then cut off and counted in a gamma counter. The results are shown in Table 1.

TABLE 1CPM 125I-IL-15 BOU...

example 2

Assessment of Toxins for Effectiveness Against B-Cell Malignancies

[0038] Three different mAbs, LL1, a class II invariant chain, LL2, an anti-CD22 antibody, and 5E9, an anti-transferrin receptor antibody, were conjugated to two RNase superfamily toxins, onconase and EDN. The resulting conjugates were tested on a panel of cell lines that included three B-lymphoma cell lines, Daudi, Raji, CA-46, a breast cancer line, MDA-MB-231, and a human T cell line, HuT 102. The results showed that LL2-onconase had the lowest IC50 values of all the conjugates tested. Toxicity of onconase-based immunotoxins on B lymphoma cell line, Daudi, was further demonstrated with conjugates of onconase and LL2. LL2 is an antibody to CD22, an efficiently internalizing antigen. Both whole IgG and Fab′ conjugates were prepared and were found to inhibit this cell line in the subnanomolar range. The effect was shown to be dependent on the CD22 reactivity of the conjugate, since inhibitory effects are nearly elimina...

example 3

Construction of a Soluble IL-15Rα-1F5scFv Fusion Protein

[0039] The hybridoma 1F5, IgG2a κ is available from the American Type Culture Collection in Rockville, Md. This hybridoma is used to produce mAb both by growth of the hybridoma in tissue culture and / or ascites with subsequent purification on protein A-agarose. It is cultured in RPMI 1640 supplemented with 2 mM L-glutamine and 50 μg / ml each of penicillin and streptomycin and 10% FCS.

[0040] For isolation of the VH and VL genes of 1F5, 3×107 cells are used for isolation of total RNA. This is done by solubilizing washed cell pellets in Trizol reagent (Gibco / BRL, Grand Island, N.Y.) followed by RNA isolation via the acid-guanidium phenol-chloroform method. Five μg of total RNA are used as template for production of 1st strand cDNA using the AMV reverse transcriptase-based kit of Boehringer-Mannheim (Indianapolis, Ind.). From 2 to 5% of the resulting reaction products is used as a template for PCR amplification of the VH and the VL...

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Abstract

A conjugate of a toxin and a cytokine, and a fusion protein comprising a bispecific antibody that has a first specificity for a cell marker specific to a malignant cell and a second specificity for a region of IL-15α, each optionally further comprising a radionuclide, are useful therapeutic reagents for treating leukemias and lymphomas.

Description

BACKGROUND OF THE INVENTION [0001] The present invention relates to a fusion protein of a component of an internalizing receptor system and a moiety that binds to a specific cellular surface marker on a cell, to a conjugate of a toxin and a ligand for the internalizing receptor system, and to a method of tumor therapy using the conjugate and internalizing receptor system. [0002] There is now a fairly large and growing body of experience in the use of monoclonal antibodies (mAbs) for the therapy of lymphoma. Several studies targeting different B-cell restricted CD (clusters of differentiation) antigens have shown promising results. These studies have used radiolabeled mAbs and, to a lesser extent, mAb-toxin conjugates, and have targeted CDs19-22, CD37, and HLA-DR. [0003] MAbs used in lymphoma therapy differ in their ability to bind cognate antigen and to become internalized. For example, CD22 exhibits efficient internalization as well as reexpression of antigen after internalization....

Claims

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Application Information

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IPC IPC(8): A61K38/00A61K39/395A61K47/48C12N15/09A61K51/00A61K51/08A61P35/00A61P35/02C07K14/54C07K14/715C07K16/28C07K16/46C07K19/00
CPCA61K38/00A61K47/48269A61K47/48561A61K51/088A61K2039/505C07K2319/00C07K14/7155C07K16/2803C07K16/2896C07K2317/622C07K14/5443A61K47/642A61K47/6849A61P35/00A61P35/02
Inventor GOLDENBERG, DAVID M.
Owner IMMUNOMEDICS INC
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