Real-World Outcome in the pre-CAR-T Era of Myeloma Patients Qualifying for CAR-T Cell Therapy

BACKGROUND: CAR-T cell therapy is likely to be introduced starting from 2021 in patients with relapsed/refractory myeloma (r/r MM) in Europe. In order to qualify for commercial CAR-T treatment, it is assumed that r/r MM patients will have to be exposed to at least three lines of previous treatments including lenalidomide, bortezomib and anti-CD38 treatment. However, the outcome of this particular subgroup of r/r MM patients is largely unknown whereas this knowledge is crucial to estimate the possible benefit of eventual CAR-T treatment. METHODS: In this non-interventional, retrospective single-center study, we analyzed all subsequent r/r MM patients treated between 01/2016 (when anti-CD38 treatment was commercially introduced in Switzerland) and 04/2020 at the University Hospital of Bern. Patients were eligible for the study if they had received at least three lines of treatment including one proteasome inhibitor (PI), one immunomodulatory drug (IMID) and one anti-CD38 antibody, and if they were in need of subsequent treatment and effectively received further lines of treatment. RESULTS: Among 56 patients fulfilling the criteria of at least three lines of treatment including PI, IMID and anti-CD38 treatment, only 34 (60%) effectively received subsequent further therapy. This suggests that 40% of r/r MM patients never receive additional treatment after at least three lines of treatment including PI, IMID and anti-CD38 treatment. For patients receiving further treatment, the median number of previous lines of treatment was 4.5 (range 2–12), including autologous stem cell transplantation in 31 (91%) patients. 13 (37%) patients were penta-refractory. The most frequently used treatment options were IMID/dexamethasone treatment in 11 (32%) patients, followed by PI/dexamethasone in 10 (29%) patients. 21 (62%) patients received two or more additional lines of therapy. The median PFS was 6.6 months (range 0–36.6 months), the median TTNT was 7.5 months (range 1.4–24.5 months) and the median OS was 13.5 months, (range 0.1–38 months) for the first subsequent treatment. The overall response rate (ORR) to the first subsequent treatment was 41%, with a median duration of the response of 5 months (range 1–37 months). 12% of the patients achieved VGPR or better, with a median duration of response of 8 months (range 3–37 months). CONCLUSIONS: Myeloma patients refractory after at least three lines of anti-CD38/PI/IMID treatment have a poor prognosis with a PFS of 6.6 months and OS of 13.5 months. These data may serve as reference to compare the potential benefit of CAR-T treatment in this group of myeloma patients when available in the near future.