Multiple myeloma (MM), a common and aggressive hematological malignancy, continues to pose a significant challenge for clinicians worldwide due to its high rates of relapse and drug resistance. Despite advancements in proteasome inhibitors, immunomodulatory drugs, and autologous stem cell transplantation (ASCT), MM remains incurable for most patients. The urgent need for more effective treatments has propelled immunotherapy to the forefront of MM research and clinical care.
A New Era of Immunotherapy for MM
A recent review published in Experimental Hematology & Oncology by researchers from the University Hospital Bonn Comprehensive Cancer Center in Germany and Renji Hospital, Shanghai Jiao Tong University School of Medicine, offers an in-depth analysis of the latest advances in adoptive cell therapy (ACT) for MM. The article highlights groundbreaking clinical data on CAR-T cell therapies—especially those targeting BCMA—and bispecific antibodies like teclistamab and elranatamab, while exploring the future potential of NK cell therapies and TCR-T therapies.
CAR-T Cell Therapies: Changing the Game
CAR-T cell therapy involves engineering a patient’s own T cells to express a chimeric antigen receptor (CAR) that targets specific tumor antigens. This breakthrough approach has demonstrated remarkable clinical results in MM, particularly targeting BCMA:
- Fucaso (Equecabtagene Autoleucel): In the pivotal FUMANBA-1 trial conducted across multiple centers in China, this BCMA-targeted CAR-T therapy demonstrated an impressive overall response rate (ORR) of 96.1% in patients with relapsed/refractory multiple myeloma (RRMM), with the ORR reaching 98.9% in those without prior CAR-T therapy. With a median follow-up of 13.8 months, deep and durable responses were observed. Notably, only 1 patient (≈1%) experienced ≥ Grade 3 cytokine release syndrome (CRS), and no ≥ Grade 3 immune effector cell-associated neurotoxicity syndrome (ICANS) was reported, reflecting a highly favorable safety profile.
- Zevor-cel (Zevorcabtagene Autoleucel): Based on results from the open-label, single-arm, multi-center Phase II LUMMICAR STUDY 1 in China, Zevor-cel, another BCMA-targeted CAR-T product, achieved an overall response rate (ORR) of 92.2% in relapsed/refractory multiple myeloma (RRMM) patients, with a complete remission (CR) rate of 71.6%. The treatment demonstrated a favorable safety profile, with ≥ Grade 3 adverse events occurring in only 6.9% of patients.
- Idecabtagene vicleucel (Abecma): In the pivotal KarMMa trial, this BCMA-targeted CAR-T achieved an overall response rate (ORR) of 73% in relapsed/refractory MM (RRMM) patients, with a complete response (CR) rate of 33% and a median duration of response (mDOR) of 11 months. Common side effects included cytokine release syndrome (CRS, 85%) and neurotoxicity (18%).
- Ciltacabtagene autoleucel (Carvykti): Based on dual-epitope binding CAR-T design, Carvykti achieved an astonishing 98% ORR and 83% stringent complete response (sCR) rate in the CARTITUDE-1 study, with a 2-year progression-free survival (PFS) rate of 61% and overall survival (OS) rate of 74%.
Beyond BCMA, new targets such as GPRC5D and CD38 are being explored to overcome antigen loss and treatment resistance:
- MCARH109, a GPRC5D-targeted CAR-T, has shown early promise, particularly in patients who relapsed after BCMA-targeted therapies.
- CD38 and SLAMF7 CAR-T therapies are also under investigation, though they present unique challenges such as off-target toxicity and self-killing T cell activity.
Bispecific Antibodies: An Accessible Alternative
Bispecific antibodies (BsAbs) simultaneously engage tumor antigens and CD3 on T cells, redirecting immune responses against MM cells without the need for individualized cell engineering.
Key agents include:
- Teclistamab: The first approved BCMA×CD3 BsAb, showed a 63% ORR and 39.4% CR rate in the MajesTEC-1 trial. It was approved by China’s NMPA in June 2024 for RRMM patients after three prior therapies.
- Elranatamab: Reported a 61% ORR and 14.7-month mDOR in MagnetisMM-3 and received conditional NMPA approval in March 2025.
- Talquetamab: A GPRC5D×CD3 BsAb, achieved a 73% ORR and 58.8% ≥VGPR rate in the MonumenTAL-1 study, with approval granted by the NMPA in February 2025.
Emerging Immunotherapy Options
- CAR-NK Cell Therapy: Offers a similar tumor-killing mechanism to CAR-T, with reduced risks of CRS and neurotoxicity and potential for off-the-shelf availability.
- TCR-T Cell Therapy: Targets intracellular tumor antigens presented via HLA, overcoming the limitation of CAR-T’s surface antigen dependence.
- Tumor Vaccines: Aim to stimulate patient-specific anti-myeloma immunity.
Challenges and Future Directions
While immunotherapy has transformed MM treatment, several hurdles remain:
- Managing Adverse Events: CRS and ICANS are common and potentially life-threatening. Early identification and management protocols are essential.
- Resistance Mechanisms: Tumor antigen loss (e.g., BCMA downregulation), T cell exhaustion, and immunosuppressive microenvironments contribute to resistance.
- Accessibility and Affordability: CAR-T cell production is complex and expensive, limiting widespread application. Bispecific antibodies, though more accessible, still face questions about long-term efficacy.
- Optimizing Combination Strategies: Integrating immunotherapies with standard treatments could enhance efficacy.
- Personalized Medicine: Tailoring immunotherapy based on individual patient profiles, disease biology, and immune characteristics is a key future focus.
Conclusion
The therapeutic landscape of multiple myeloma is undergoing a paradigm shift, with CAR-T cell therapies and bispecific antibodies leading the charge. These innovative immunotherapies, while highly promising, require continued optimization in clinical practice to enhance safety, durability, and patient access. As our understanding of MM immunobiology deepens, more effective, personalized, and accessible treatments are on the horizon—offering new hope for improved survival and quality of life in MM patients.
