FLT3-specific chimeric antigen receptors and methods using same
Inventors
Chien, Christopher D. • Fry, Terry J.
Assignees
US Department of Health and Human Services
Publication Number
US-11299546-B2
Publication Date
2022-04-12
Expiration Date
2037-05-26
Interested in licensing this patent?
MTEC can help explore whether this patent might be available for licensing for your application.
Abstract
An embodiment of the invention provides a chimeric antigen receptor (C AR) comprising an antigen binding domain specific for FLT3, a transmembrane domain, and an intracellular T cell signaling domain. Nucleic acids, recombinant expression vectors, host cells, populations of cells, antibodies, or antigen binding portions thereof, and pharmaceutical compositions relating to the CARs are disclosed. Methods of detecting the presence of a proliferative disorder, e.g., cancer, in a mammal and methods of treating or preventing a proliferative disorder, e.g., cancer, in a mammal are also disclosed.
Core Innovation
The invention provides chimeric antigen receptors (CARs) comprising an antigen binding domain specific for FLT3, a transmembrane domain, and an intracellular T cell signaling domain. The CAR may further include a 4-1BB intracellular domain, a spacer, or both. These CARs are designed based on antibodies, such as NC7, and may contain single chain variable fragments (scFv) with specified heavy and light chain variable regions linked by suitable linkers, including glycine-serine linkers.
The problem addressed by the invention is the lack of effective treatments for certain leukemic patient populations, such as infants with pre-B cell precursor acute lymphoblastic leukemia (ALL) or acute myeloid leukemia (AML), who have low survival rates despite standard therapies. Current CAR T cell therapies mostly target CD19 but face issues of relapse due to antigen loss. FLT3 is frequently mutated and overexpressed in AML and infant ALL, making it a promising target resistant to down-modulation escape mechanisms.
The inventive CARs specifically bind FLT3 antigen and can elicit antigen-specific immune responses. They enable targeting and destruction of FLT3-expressing cancer cells and may facilitate immune cell infiltration into tumors, thereby enhancing anti-cancer responses. The CARs can be encoded by nucleic acids, inserted into recombinant vectors, expressed in host cells including T cells, and used in pharmaceutical compositions. Methods include detecting cancer presence and treating or preventing proliferative disorders, particularly FLT3-expressing leukemias.
Claims Coverage
The patent claims encompass several inventive features related to the composition and use of chimeric antigen receptors targeting FLT3, nucleic acids encoding them, vectors, host cells, antibodies, pharmaceutical compositions, and methods for detecting and treating cancer.
Chimeric antigen receptor targeting FLT3 with specific scFv CDR sequences
A CAR comprising an antigen binding domain specific for FLT3, wherein the domain is a single chain variable fragment comprising the heavy chain variable region CDR1, CDR2, and CDR3 sequences of SEQ ID NOS: 6, 8, and 10 and the light chain variable region CDR1, CDR2, and CDR3 sequences of SEQ ID NOS: 14, 16, and 18.
Antigen binding domain comprising specified variable regions and linker
The antigen binding domain comprises light chain variable region sequences SEQ ID NOS: 13-19 and heavy chain variable region sequences SEQ ID NOS: 5-11, with a linker sequence SEQ ID NO: 12, forming the scFv.
Transmembrane domain comprising CD8 sequences
The transmembrane domain comprises the CD8 alpha hinge sequence of SEQ ID NO: 25 and the transmembrane domain of SEQ ID NO: 26.
Intracellular T cell signaling domain with 4-1BB and CD3 zeta sequences
The intracellular signaling domain includes the 4-1BB amino acid sequence of SEQ ID NO: 27 and the CD3 zeta amino acid sequence of SEQ ID NO: 28, which provide costimulatory and activation signals.
Inclusion of spacer sequences
The CAR further includes spacer sequences comprising SEQ ID NOS: 21-24, such as IgG heavy chain constant domain spacers, positioned between domains to assist functionality.
Nucleic acid and recombinant vector encoding the CAR
Nucleic acids encoding the CAR can be codon-optimized and inserted into recombinant expression vectors, including lentiviral vectors, for expression in host cells.
Host cells and cell populations expressing the CAR
Isolated host cells, particularly T cells or non-T immune effector cells, comprising recombinant expression vectors encoding the CAR; populations of such cells can be used in therapies.
Antibodies specifically binding the CAR
Antibodies or antigen binding portions specifically recognizing the CAR, useful for detection or therapeutic purposes.
Pharmaceutical compositions including the CAR materials
Compositions comprising the CAR, nucleic acids, vectors, host cells, antibodies, or their antigen binding portions together with pharmaceutically acceptable carriers.
Methods of detecting cancer using the CAR or related materials
Methods comprising contacting a sample containing cells with the CAR, nucleic acids, vectors, host cells, antibodies, or pharmaceutical compositions and detecting complexes indicative of cancer presence.
Methods of treating or preventing cancer by administering CAR-expressing cells
Administering host cells or populations expressing the CAR to treat or prevent FLT3-positive cancers, in particular pre-B cell precursor acute lymphoblastic leukemia or acute myeloid leukemia.
Determining patient candidacy for treatment by measuring FLT3 expression
Measuring FLT3 expression levels in biological samples to determine if a subject is suitable for treatment with the FLT3-specific CAR.
The claims collectively cover the molecular composition of FLT3-specific CARs with defined variable regions, linkers, transmembrane and signaling domains; encoding nucleic acids and vectors; host cells; antibodies; pharmaceutical formulations; and methods for detecting and treating FLT3-expressing cancers, notably ALL and AML.
Stated Advantages
The CARs specifically target FLT3-expressing cancer cells, reducing or eliminating them.
By targeting both wild type and mutant FLT3, the CARs provide broad targeting of infant ALL and AML.
The CARs can overcome tumor escape mechanisms by recognizing antigen independent of MHC processing.
Inclusion of costimulatory domains such as 4-1BB enhances T cell survival and function.
Documented Applications
Detecting the presence of proliferative disorders, such as cancer, in a mammal by contacting samples with the CAR or related materials and detecting complexes.
Treating or preventing cancer, particularly FLT3-positive malignancies including pre-B cell precursor acute lymphoblastic leukemia and acute myeloid leukemia, by administration of CAR-expressing host cells or related compositions.
Determining if a subject with a proliferative disorder is a candidate for CAR treatment by measuring FLT3 expression levels in biological samples.
Interested in licensing this patent?