Introduction Autologous stem cell transplantation (ASCT) is a frontline treatment for multiple myeloma (MM), but can result in T cell dysfunction, which in turn may reduce the effectiveness of subsequent CAR T-cell therapy (Gustine, 2024). The KarMMa-2 (NCT03601078) phase 2 multicenter trial evaluated the efficacy of idecabtagene vicleucel (ide-cel), a BCMA-directed CAR T cell therapy, in high-risk MM cohorts, including patients with suboptimal response to ASCT. Although ide-cel demonstrated promising outcomes, a subset of patients failed to respond, underscoring the need to address T cell fitness post ASCT.

This analysis focuses on two specific cohorts: cohort 2c (C2c), enrolling newly diagnosed MM (NDMM) patients with a best overall response (BOR) of < VGPR after frontline ASCT, and cohort 3 (C3), enrolling NDMM patients with less than complete response (CR) after ASCT. The median time from ASCT to enrollment was 5.8 months for C2c and 4.2 months for C3. C2c achieved an overall response rate (ORR) of 87.1% and a complete response rate (CRR) of 80.6% with ide-cel, but some patients still did not respond optimally (Paul, 2024). Cohort 3 incorporated a cycle of lenalidomide (LEN) before apheresis to assess its effect on markers of T cell health and patient outcomes. We present the findings of a cross-cohort analysis to assess the impact of pre-apheresis LEN on T cell fitness, drug product characteristics, pharmacokinetic (PK), and pharmacodynamic (PD) features.

Methods Immune profiling of peripheral blood mononuclear cells (PBMCs) was performed at baseline and day 15 (D15) using a Mass Cytometry by Time-of-Flight (CyTOF) panel with 35 markers in 31 patients from C2c and 30 patients from C3. Additional analyses included cytokine and chemokine profiling by immunoassay and proteomic analysis with the OLINK 3K panel. Drug product material was characterized using high-parameter flow cytometry and immunoassay, while cellular kinetics were evaluated by droplet digital polymerase chain reaction. Tumor burden and patient health were also clinically assessed.

Results Baseline soluble BCMA (sBCMA), indicating tumor burden, was lower in both C2c and C3 NDMM populations compared to relapsed/refractory MM (RRMM) patients, but C2c showed higher sBCMA (27 ng/mL) than C3 (14.5 ng/mL). Immunophenotyping revealed that C3 had improved T cell fitness, with higher CD8 Tem and lower CD8 Temra subtypes, as well as reduced expression of CD57, PD1, and CD38 on CD4 and CD8 T cells. C3 patients also exhibited lower Ki67 and CTLA4 on CD4 T cells, and higher CD27 expression on CD4 Tcm and Tem, suggesting a less differentiated and potentially more effective drug product phenotype.

Cohort 3 demonstrated increased levels of IL2, IL7, and perforin (PRF), which may support enhanced CAR T cytotoxic activity, while lower levels of IFNγ indicated a more favorable immune microenvironment. Baseline proteomics revealed significant differential expression of >200 analytes between C2c and C3, with pathway enrichment analyses highlighting involvement of Hallmark MYC target genes. Drug product analysis showed a trend for higher potency and lower CD57 expression on CD4 and CD8 cells in C3, consistent with increased cytolytic potential.

At D15 post-infusion, C3 had higher abundance of Tem and lower abundance of Tcm subtypes in both CD4 and CD8 CAR T cells. PD1 and CD38 expression remained lower on both endogenous and CAR T cells in C3. CAR T-cell expansion was comparable between C2c and C3, with cellular kinetics similar to those observed in RRMM patients treated with ide-cel in the KarMMa-3 trial. Cohort 3 also showed superior clearance of sBCMA in 93.3% (28/30) of patients, compared to 77.4% (24/31) in C2c, indicating enhanced PD activity.

ConclusionsA cycle of LEN pre-apheresis improved T cell fitness, leading to better drug product profiles and enhanced PD activity in cohort 3 patients.

This content is only available as a PDF.
2025
Sign in via your Institution