2024 EBMT : China’s First RRMM CAR-T Therapy Equecabtagene Autoleucel: Efficacy Unaffected by Patients’ Baseline sBCMA Plasma Levels
2024 EBMT : China’s First RRMM CAR-T Therapy Equecabtagene Autoleucel: Efficacy Unaffected by Patients’ Baseline sBCMA Plasma Levels
RRMM
In recent years, CAR-T cell therapy targeting BCMA has emerged as a groundbreaking treatment for multiple myeloma, offering new hope to patients. At the 50th European Society for Blood and Marrow Transplantation (EBMT) Annual Meeting, held from April 14-17, 2024, in Glasgow, the team led by Professor Qiu Lugui presented the latest subgroup analysis results from the FUMANBA-1 study (Abstract OS10-04) on China’s first BCMA-targeted CAR-T therapy, Iquilencel (CT103A).
BCMA (B-cell maturation antigen) is a promising therapeutic target for multiple myeloma (MM), with soluble BCMA (sBCMA) levels in the blood reflecting tumor burden. High sBCMA levels can interfere with the effectiveness of BCMA-targeted therapies, including CAR-T, by competing with cell-surface BCMA for binding, which can lead to reduced efficacy. In contrast, Iquilencel has been designed to minimize the impact of sBCMA on treatment outcomes through careful selection of its single-chain variable fragment (scFv).
The FUMANBA-1 phase II study (NCT05066646) in Chinese patients with relapsed/refractory multiple myeloma (RRMM) has demonstrated that Iquilencel can induce deep and durable responses, with a complete response (CR) rate of 82.4% and a 12-month progression-free survival (PFS) rate of 85.5%. This study aimed to explore whether baseline serum sBCMA levels affect clinical outcomes following Iquilencel infusion.
### Study Methods and Results
The study used enzyme-linked immunosorbent assay (ELISA) to measure serum sBCMA levels and digital droplet PCR (ddPCR) to monitor CAR transgene copy numbers in patients’ peripheral blood. Baseline serum sBCMA levels were classified into high (≥225.1 ng/mL) and low (<225.1 ng/mL) groups. Results showed that high sBCMA levels were significantly associated with high tumor burden, advanced R-ISS and DS stages, and high BCMA expression. However, there were no significant differences in CAR-T cell expansion, AUC (Area Under the Curve) during the first 28 days, or cell persistence between the high and low sBCMA groups.
Patients with high baseline sBCMA levels had overall response rates (ORR) and ≥CR rates of 100% and 80%, respectively, compared to 97.8% and 84% in the low sBCMA group. Analysis showed no significant correlation between baseline characteristics (including sBCMA levels) and CR/sCR achievement. Additionally, there were no significant differences in minimal residual disease (MRD) negativity rates, 18-month sustained MRD negativity rates, PFS, and overall survival (OS) between the two groups.
### Conclusion
The findings from the FUMANBA-1 study indicate that Iquilencel’s efficacy is not influenced by baseline sBCMA levels, making it a universally applicable and promising treatment option for RRMM patients. Its unique fast-dissociation and low-exhaustion properties, similar to those of healthy T-cell receptors, enable Iquilencel to remain effective and persistent in patients’ bodies regardless of sBCMA levels.
Professor Qiu Lugui from the Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences, and Professor Li Chunrui from Tongji Hospital, Huazhong University of Science and Technology, noted, “sBCMA is an important biomarker of tumor burden in multiple myeloma and a key factor influencing prognosis. Accumulation of sBCMA can inhibit the function of BCMA CAR-T cells. However, our study shows that Iquilencel can overcome the challenges posed by high baseline sBCMA levels, providing significant and lasting responses for RRMM patients.”
These results underscore Iquilencel as an ideal treatment choice for RRMM, offering hope for more effective and long-lasting therapeutic outcomes.