Impact of Extramedullary Disease on Outcomes in RRMM Patients Receiving CAR T Therapy

Overview

This multicenter retrospective study evaluated the prognosis of relapsed-refractory multiple myeloma (RRMM) patients with active extramedullary disease (EMD) treated with commercial anti-BCMA CAR T-cell therapy. Findings indicate that EMD presence is associated with poorer progression-free and overall survival post-CAR T infusion, highlighting its role as a negative prognostic factor.

Background

Extramedullary disease (EMD) is an uncommon but aggressive manifestation of multiple myeloma, typically emerging in relapsed-refractory cases with an incidence of 3-14%. EMD is linked to adverse cytogenetics and treatment resistance, complicating management due to lack of consensus guidelines. CAR T-cell therapies targeting BCMA, such as idecabtagene vicleucel and ciltacabtagene autoleucel, have transformed RRMM treatment, but recent data suggest EMD predicts early progression after CAR T therapy. This study aimed to assess outcomes of RRMM patients with active EMD undergoing commercial CAR T-cell therapy.

Data Highlights

Key Findings

• Active extramedullary disease (EMD) was defined as bone-independent plasma cell tumors detected within 30 days before CAR T infusion.
• Patients with EMD had significantly worse progression-free survival (PFS) and overall survival (OS) after CAR T therapy compared to those without EMD.
• EMD was associated with high-risk cytogenetic abnormalities such as deletion 17p, t(4;14), and t(14;16).
• Visceral EMD involved major organs including liver, lungs, spleen, and pancreas, representing a particularly aggressive disease subset.
• Patients with paramedullary disease (PMD) only were analyzed separately to distinguish outcomes from true EMD.
• Standard lymphodepleting chemotherapy and bridging therapies were administered prior to CAR T infusion, with response assessed by IMWG criteria and imaging modalities.

Clinical Implications

Clinicians should recognize active EMD as a high-risk feature in RRMM patients considered for CAR T-cell therapy, as it predicts inferior survival outcomes. Comprehensive imaging to detect EMD prior to infusion is essential for risk stratification and treatment planning. Further research is needed to develop tailored therapeutic strategies for this subgroup to improve prognosis.

Conclusion

Active extramedullary disease significantly compromises the efficacy of commercial anti-BCMA CAR T-cell therapy in relapsed-refractory multiple myeloma, underscoring the need for specialized management approaches. This study provides critical real-world evidence to guide prognosis and therapeutic decision-making in this challenging patient population.

References

1. Usmani et al. 2021 -- Idecabtagene vicleucel in RRMM
2. Munshi et al. 2022 -- Ciltacabtagene autoleucel in RRMM
3. US Myeloma Innovations Research Collaborative (USMIRC) Study 2023 -- Outcomes of RRMM with EMD post CAR T
4. ASTCT Consensus Criteria 2019 -- CRS and ICANS Grading
5. IMWG Response Criteria 2016 -- Multiple Myeloma Response Assessment