Bendamustine Bridging Versus Standard of Care Chemotherapy on Toxicity Profile for Multiple Myeloma Patients Undergoing CAR T Cell Therapy

Introduction

Multiple myeloma (MM) remains an incurable malignancy arising from plasma cells, however great promise has been seen with the use of Chimeric Antigen Receptor (CAR) T cells. Autologous CAR-T products require bridging therapy, however little is known about different agents used in this manner. Some studies indicate decrease in disease burden is crucial, while others note an association with higher rates of toxicity and negative effect on survival. As commercial CAR T cell therapy is indicated after failure of at least 4 prior treatments, careful consideration of bridging therapy is crucial, particularly in patients with aggressive and high-risk disease. This study aims to compare the impact of bendamustine to standard of care (SOC) bridging therapy in MM patients undergoing CAR T cell therapy.

Methods

A single-center retrospective chart review of 19 adult patients with relapsed/refractory multiple myeloma treated with CAR T cells, who also received bridging therapy with either bendamustine (n=9) or SOC/Other (n=10) was conducted at Mount Sinai Hospital. Patient demographic information (gender, race, MM subtype, history of prior transplant) was collected and toxicity profiles (infection, pancytopenia, cytokine release syndrome (CRS), and immune effector cell-associated neurotoxicity syndrome (ICANS)) were compared. Descriptive statistics were used to analyze demographic characteristics and toxicity profiles between the two cohorts.

Results

Comparative analysis of demographics showed that both cohorts were predominantly males with IgG MM subtype, and varied in terms of race ( Figure 1a). The Other cohort had a higher proportion of patients with a history of autologous stem cell transplant (ASCT) (70%) compared to the bendamustine group. In the SOC group, two patients developed infections, whereas none were observed in the bendamustine cohort ( Figure 1b). Pancytopenia was observed in both groups, but interestingly, 100% of patients experienced it in the SOC cohort. CRS and ICANS were comparable between the two groups ( Figure 1b). Comparative statistics demonstrated no significant difference between the two groups ( Figure 1c).

Conclusion

Our study findings indicate that there was no significant difference in toxicity profiles between the two pre-conditioning therapy groups. Given our limited sample size, future studies with a larger are indicated to validate these results.