Distinct Patterns of Lymphoid Immune Reconstitution After Bcma-directed Car-t Therapy in Relapsed/refractory Multiple Myeloma
Year: 2026
Type: article
Abstract: Background BCMA-directed CAR-T therapy has improved outcomes in relapsed/refractory multiple myeloma (RR-MM). However, responses remain heterogeneou, suggesting that immune recovery extends beyond CAR-T expansion alone. Although most studies focus on the infused cellular product, remodeling of CAR-positive T cells, endogenous CAR-negative T cells, and natural killer (NK) cells during early immune reconstitution remains poorly understood. Aim To characterize early lymphoid immune remodeling after BCMA-directed CAR-T therapy by integrating CAR-positive and CAR-negative T-cell compartments, CD4/CD8 balance, memory differentiation, immune checkpoints, and NK-cell subsets. Methodology: Patients with RR-MM treated with BCMA-directed CAR-T cells were prospectively enrolled (CAAE: 65750722.3.0000.5432). Blood samples were collected before infusion and 30 days after treatment. PBMC were analyzed by multiparametric flow cytometry to assess CAR-positive and CAR-negative CD4⁺ and CD8⁺ T-cell subsets, memory differentiation, checkpoint expression, and conventional and non-conventional NK-cell phenotypes. Paired changes between baseline and day 30 were evaluated. Results Paired analyses of three patients revealed marked interindividual heterogeneity in early lymphoid reconstitution. Circulating CAR-T frequencies ranged from robust expansion to minimal detectable expansion at D30. Total CD4⁺ and CD8⁺ T-cell compartments followed distinct trajectories, producing divergent CD4/CD8 architectures. The responding patient exhibited a more balanced CD4/CD8 ratio, whereas the two non-responders developed CD4- or CD8-dominant profiles. Corresponding alterations in CD4/CD8 balance were also observed within the CAR-negative compartment, indicating that remodeling extended beyond the infused product. Effector-memory enrichment was observed across CAR-positive and CAR-negative T-cell compartments, accompanied by sustained PD-1 and reduced LAG-3 expression, particularly among CD8⁺ T cells. All patients also showed expansion of non-conventional NK cells, with relative contraction of canonical NK subsets and reduced LAG-3 expression. These findings demonstrate multi-compartment lymphoid remodeling during early immune reconstitution. Discussion: The concomitant changes observed in CAR-positive T cells, endogenous CAR-negative T cells, and NK cells suggest that early immune recovery after BCMA-directed CAR-T therapy reflects systemic lymphoid reorganization rather than expansion of the infused product alone. The expansion of non-conventional NK phenotypes across patients with markedly different CAR-T frequencies may represent a shared feature of post-lymphodepletion immune recovery. The observation that the responding patient maintained a more balanced CD4/CD8 architecture, whereas non-responders developed opposite forms of imbalance, is hypothesis-generating and suggests that the organization of immune reconstitution may be biologically relevant. However, the limited cohort precludes conclusions regarding association with clinical response. Conclusion BCMA-directed CAR-T therapy was followed by distinct patterns of early lymphoid reconstitution involving CAR-positive T cells, endogenous CAR-negative T cells, and non-conventional NK cells. These findings support further investigation of integrated lymphoid architecture, including CD4/CD8 balance, as a potential marker of immune recovery and treatment outcome in larger longitudinal cohorts.
Authors: Arianne Fagotti GUSMAO, Raquel Garcia DA SILVA, Vanessa Dos Anjos BOVOLENTA, Bianca Batista CAL, Ana Costa CORDEIRO, Daniela DELECHIAVE, Sabrina Pinho Costa MENDES, Lais Lie Senda DE ABRANTES, Alexandre Silva CHAVES, Ana Luiza Sionti PACHECO, Larissa Souza CAMPOS, Mariana Soares GOMES, Gabriel Andrade DE PAULA, Filipe Freires DOS SANTOS, Marina De Matos NASCIMENTO, Mariela Pires Cabral PICCIN, Marta Maria Moreira LEMOS, Jayr Schmidt FILHO, Martin BONAMINO, Marjorie Vieira BATISTA
Language: English
Topic: CAR-T cell therapy research
Subfield: Oncology
Field: Medicine
Domain: Health Sciences
Open Access status: diamond
OpenAlex ID: W7223110270