Rapid Hematologic Clearances and Promising Bone Marrow Responses in AL Amyloidosis

Heather J. Landau, MD, of Memorial Sloan Kettering Cancer Center, presents the finalized results of the phase 1b/2 NEXICART-2 trial (NCT06097832) evaluating NXC-201, a BCMA-directed chimeric antigen receptor (CAR) T-cell therapy specifically for patients with AL amyloidosis. The study safely proceeded through a standard dose-escalation phase, enrolling its initial 3 patients at the lowest predefined dose level. Following the absence of any dose-limiting toxicities (DLTs), the investigators successfully escalated the regimen. A subsequent cohort of approximately 42 patients received the target therapeutic dose. The trial is now complete, notably recording zero dose-limiting toxicities across the entire expanded study population.

The clinical data from this trial demonstrates profound and highly accelerated anti-plasma cell activity. A preliminary analysis tracking the first 23 treated patients revealed a 74% complete hematologic response rate at the time of data cutoff. Beyond standard blood-based metrics, a substantial majority of patients evaluated at the day 25 landmark achieved a deep response of minimal residual disease (MRD) negativity within the bone marrow. Utilizing the study’s most sensitive detection methods, investigators found no evidence of remaining abnormal clone plasma cells in the marrow at this early juncture.

Landau notes that achieving bone marrow MRD negativity is a powerful indicator of long-term success. Because serological markers tested in the blood can lag behind cellular clearance and take time to fully degrade, patients with clean bone marrow are highly expected to continue evolving into complete hematologic responders over time. This continuous depth of response is further supported by data from even earlier time points, which showed that abnormal serum free light chains normalized by day 7 or day 14 post-infusion in all patients treated with this cellular product.