Session: 651. Multiple Myeloma and Plasma Cell Dyscrasias: Basic and Translational: Poster I
Hematology Disease Topics & Pathways:
Research, Fundamental Science, Translational Research, Plasma Cell Disorders, Diseases, Immune mechanism, Treatment Considerations, Biological therapies, Immunotherapy, Immunology, Lymphoid Malignancies, Biological Processes, Emerging technologies, Technology and Procedures, Profiling, Human, Omics technologies
We collected BM biopsies and blood samples from 62 MM patients. We utilized longitudinal single-cell RNA and V(D)J sequencing to characterize the phenotype and clonality of over 500,000 BMTCs. Additionally, tumor-reactive T cells were identified by screening 187,015 T cells representing 132,501 unique TCR clonotypes for their reactivity against single autologous MM cells using a newly developed microfluidics-based screening method. We deorphanized putative tumor-reactive TCRs using patient-specific peptide libraries of tumor MHC class I and II immunopeptidomes. By synthesizing, cloning, and re-expressing these TCRs, we examined recognition of MM versus healthy patient cells. We further differentiated TCRs that cross-reacted with viral antigens (CMV, EBV, Influenza, SARS-CoV-2) from those that demonstrated bona fide MM-specificity.
We found distinct heterogeneity in patient BMTCs, with specific transcriptional signatures linked to anti-tumor functions as opposed to virus recognition or bystander activity. Deeper profiling of T cells with MM-specificity revealed a transcriptionally unique, ITGB1 (CD29)-expressing T cell subset recognizing cancer-associated antigens (CAAs) or peptides from non-canonical translation products (nuORFs). Additionally, we recurrently identified personalized neoantigens within the immunoglobulin (Ig) hypervariable region of MM clones. T cells targeting such Ig-derived antigens were found in 70% of analyzed patients. Further, a minimal epitope derived from cancer/testis antigen 2 (CTAG2) was recognized by TCRs from multiple MM patients spanning four different HLA supergroups. This data suggests the frequent occurrence of both private neoantigens derived from the hypermutated MM-Ig and public, MHC-promiscuous antigens as targets of endogenous anti-myeloma T cell responses. Surprisingly, the clonal expansion of these tumor-specific TCRs, present in only about 1.2% of assayed BMTCs but detectable in all newly diagnosed MM patients, correlated with enhanced clinical responses.
To further investigate the clinical relevance of our findings, we developed and benchmarked a transcriptional signature of anti-tumor reactivity tailored to the unique transcriptional phenotype of lymphocytes within the bone marrow environment. Applying this signature to two independent patient cohorts, we found that early detection of tumor-reactive TCRs correlates with improved responses to current SoC induction/consolidation treatment with Daratumumab-VTd (HR = 0.32, p < 0.0001) as well as BCMAxCD3 bispecific T cell engager administration (HR = 0.36, p = 0.0005) in relapsed/refractory MM.
To determine if tumor-reactive TCRs are transplanted and persist long-term, we analyzed stem cell grafts from MM patients undergoing autologous stem cell transplantation (ASCT; NCT03617731) and traced individual TCRs up to two years post-ASCT. We found that tumor-reactive TCRs were enriched in these grafts, preferentially transplanted, and maintained long-term persistence, potentially contributing to the therapeutic value of ASCT. Furthermore, the presence of these TCRs in the bone marrow correlated with long-term clinical responses, indicating their role in sustaining anti-myeloma immunity.
Here, we systematically profiled and consistently detected T cells with endogenous anti-tumor reactivity in MM patients. Our data suggest that tumor-reactive TCRs play a critical role in mediating anti-myeloma responses and are influenced by both intrinsic properties and microenvironmental factors. Ongoing studies aim to further elucidate how these TCRs contribute to long-term immune surveillance and therapeutic responses in MM, with potential implications for the development of more effective immunotherapies.
Disclosures: Goldschmidt: Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Support for attending meetings and/or travel, Research Funding; Adaptive Biotechnologies: Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Support for attending meetings and/or travel; grants and/or provision of Investigational Medicinal Product, Research Funding; Celgene: Research Funding; Chugai: Honoraria, Other: Grants and/or provision of Investigational Medicinal Product; GlaxoSmithKline (GSK): Honoraria, Other: Support for attending meetings and/or travel, Research Funding; GlycoMimetics Inc.: Research Funding; Heidelberg Pharma: Research Funding; Hoffmann-La Roche: Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants and/or provision of Investigational Medicinal Product; support for attending meetings and/or travel, Research Funding; Incyte Corporation: Research Funding; Karyopharm: Research Funding; Merck Sharp and Dohme (MSD): Research Funding; Millennium Pharmaceuticals Inc.: Research Funding; Molecular Partners: Research Funding; MorphoSys AG: Research Funding; Novartis: Honoraria, Other: Support for attending meetings and/or travel, Research Funding; Pfizer: Honoraria, Other: Support for attending meetings and/or travel, Research Funding; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants and/or provision of Investigational Medicinal Product; support for attending meetings and/or travel, Research Funding; Takeda: Research Funding; Array Biopharma/Pfizer: Other: Grants and/or provision of Investigational Medicinal Product; Bristol Myers Squibb/Celgene: Other: Grants and/or provision of Investigational Medicinal Product; Dietmar Hopp Foundation: Other: Grants and/or provision of Investigational Medicinal Product; Johns Hopkins University: Other: Grants and/or provision of Investigational Medicinal Product; Mundipharma GmbH: Other: Grants and/or provision of Investigational Medicinal Product. Weinhold: Sanofi-Aventis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; The Binding Site: Research Funding; BMS/Celgene: Research Funding; GlaxoSmithKline (GSK): Membership on an entity's Board of Directors or advisory committees. Carr: Kymera: Membership on an entity's Board of Directors or advisory committees; PrognomIQ: Membership on an entity's Board of Directors or advisory committees; Seer: Membership on an entity's Board of Directors or advisory committees; PTM BioLabs: Membership on an entity's Board of Directors or advisory committees. Raab: Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel expenses, Research Funding; Oncopeptides: Consultancy, Honoraria, Other: travel expenses; Sanofi: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; GSK: Consultancy, Membership on an entity's Board of Directors or advisory committees; Heidelberg Pharma: Research Funding; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel expenses; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel expenses, Research Funding. Friedrich: Pfizer: Honoraria, Speakers Bureau; Roche: Research Funding; Kerna Ventures: Honoraria, Speakers Bureau.
See more of: Oral and Poster Abstracts