CAR-T Cell Adapter for Selective Stem Cell Elimination
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Solution Overview
Problem
Current hematopoietic stem cell transplantation methods, particularly allogeneic transplantation, cause significant toxicity to non-hematopoietic tissues like bone marrow stromal cells due to the use of alkylating agents, leading to impaired hematopoiesis and increased morbidity and mortality, especially in non-malignant monogenic diseases and DNA repair-deficient patients.
Innovation Solution
A combination of compositions involving chimeric antigen receptor (CAR)-modified T cells and accessory cell populations to specifically target and eliminate hematopoietic stem cells while preserving bone marrow stromal cells, followed by enhanced engraftment of CD34+ stem cells with contributory cell populations to promote attachment and survival in the bone marrow niche.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alkylating agents (busulfan) are used for myeloablation in allogeneic hematopoietic stem cell transplantation, then donor stem cell engraftment is achieved, but toxicity to non-hematopoietic tissues (bone marrow stromal cells) increases, impairing hematopoiesis
Solution Approach 1:
The patent uses an adapter molecule as an intermediary that bridges the CAR-T cell and the hematopoietic stem cell. The adapter consists of a first binding domain specific for a hematopoietic stem cell antigen (e.g., CD34, CD90) and a second binding domain specific for the CAR-T cell receptor. This intermediary enables specific targeting of HSCs without requiring direct recognition, allowing selective elimination while preserving stromal cells and reducing off-target toxicity.
Solution Approach 2:
The invention applies local quality by making the CAR-T cell therapy specific only to hematopoietic stem cells through the adapter molecule. The first binding domain of the adapter is designed to bind specifically to antigens expressed on HSCs (such as CD34, CD90, CD133), while leaving other bone marrow cells including stromal cells unaffected. This localized specificity ensures that only the intended target cells are eliminated while preserving the bone marrow microenvironment.
2Reliability
If high-dose chemotherapy and whole-body irradiation are used for conditioning, then malignant cells are eradicated and immune suppression is achieved, but morbidity and mortality risk increases significantly
Solution Approach 1:
The patent extracts the essential function of myeloablation (clearing space for donor engraftment) from the harmful conventional approach (high-dose chemotherapy and irradiation). Instead of using cytotoxic agents that damage all rapidly dividing cells, the invention uses CAR-T cells directed against HSCs to selectively eliminate hematopoietic cells through immune-mediated mechanisms. This extraction separates the therapeutic effect (HSC elimination) from the harmful effects (tissue toxicity, mortality) associated with traditional conditioning.
Solution Approach 2:
The invention replaces the mechanical/chemical system of high-dose chemotherapy and radiation with a biological immune system approach. CAR-T cells are genetically engineered to recognize and kill HSCs expressing specific antigens. This substitution uses the body's own immune machinery rather than external toxic agents, thereby achieving myeloablation with significantly reduced toxicity to non-hematopoietic tissues and lower mortality risk.
3Reliability
If busulfan is administered for conditioning, then donor stem cell transplantation is enabled, but bone marrow stromal cell function is permanently damaged, reducing support for hematopoiesis
Solution Approach 1:
The adapter molecule serves as a specific intermediary that mediates the interaction between CAR-T cells and hematopoietic stem cells. The first binding domain targets antigens uniquely or preferentially expressed on HSCs (such as CD34, CD90, CD133), ensuring that busulfan-free conditioning selectively eliminates HSCs while leaving stromal cells intact. This specificity prevents the permanent stromal cell damage caused by conventional busulfan therapy.
Solution Approach 2:
The invention changes the parameter of cell targeting specificity by using the adapter molecule with its dual binding domains. Rather than using a non-specific cytotoxic agent like busulfan that affects all dividing cells, the CAR-T cell system with the adapter achieves selective HSC elimination by recognizing specific surface antigens. This parameter change from non-specific to specific targeting preserves stromal cell function and enables sustained hematopoietic support.
Data Source
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AI summary
The present invention provides a combination of compositions comprising i) a composition comprising I) a population of T cells, NK cells or cytotoxic immune effector cells comprising a chimeric antigen receptor specific for a stem cell antigen and/or, II) α) a population of T cells, NK cells or cytotoxic immune effector cells comprising a chimeric antigen receptor specific for a tag of a tagged polypeptide, wherein said tagged polypeptide binds specifically to a stem cell antigen, and β) said tagged polypeptide, and ii) a composition comprising a) a population of CD34+ hematopoietic stem cells, and b) one or more accessory or contributory cell populations selected from the group consisting of myeloid cell lineages expressing CD14, CD11b, CD11c, CD123, CD33; CD36; CD47, CD66b, CD235a, CD146 and CD326. A method applying these compositions to a subject in need thereof are also provided.