Second autologous stem cell transplant: an effective therapy for relapsed multiple myeloma.

Therapeutic options for patients with multiple myeloma (MM) whose disease has relapsed after a prior autologous stem cell transplant (ASCT) include an expanding armamentarium of novel agents, often combined with traditional chemotherapy, or a second ASCT, with no clear standard of care. We retrospectively analyzed the outcomes of 75 patients who underwent salvage melphalan-based ASCT for relapsed MM at Memorial Sloan-Kettering Cancer Center between 1995 and 2012. Conditioning was performed with melphalan 200 mg/m(2) (n = 43), 180 mg/m(2) (n = 1), 140 mg/m(2) (n = 22), and 100 mg/m(2) (n = 9). The median age at second ASCT was 59 years (range, 36 to 75), and 58% (n = 35) were men. Of those with available data, 19% had high-risk cytogenetics (including t (4;14), p53 loss, or del 13q by karyotype) at the time of second ASCT. Median interval between first and salvage ASCT was 37.5 months (range, 6.9 to 111.4). Of 72 assessable patients, 57% had chemotherapy-sensitive disease before to salvage ASCT and 43% were chemoresistant. Four patients died within 100 days of ASCT. Response was assessed at 2 to 3 months post-ASCT, and of 71 assessable patients, 82% achieved at least a partial response, 15% had stable disease, and 3% progressed despite salvage ASCT. After salvage ASCT, 38 patients received maintenance therapy and 14 went on to allogeneic ASCT. The median progression-free survival (PFS) after second autograft was 10.1 months (95% confidence interval [CI], 7.6 to 13.4) and median overall survival (OS) 22.7 months (95% CI, 19.2 to 41.2). Patients with chemosensitive relapse had a trend toward better PFS (hazard ratio [HR], .60 [95% CI, .36 to 1.02]; P = .058) and significantly longer OS (HR, .49 [95% CI, .27 to .88]; P = .017) than patients with resistant relapse. Those with high-risk cytogenetics at the time of second ASCT had higher risk of death (HR, 2.98 [95% CI, 1.28 to 6.97]; P = .012) compared with patients with standard-risk cytogenetics. Salvage ASCT is an effective strategy for relapsed MM with chemosensitive disease and results in comparable PFS and OS to other salvage strategies.