Autologous versus allogeneic stem cell transplant for multiple myeloma

Abstract

We report results of a comparative analysis of 87 patients with multiple myeloma, treated with either autologous PBSCT (n = 70) or allogeneic sibling donor myeloablative transplant (n = 17) using cyclophosphamide and fractionated TBI conditioning. Autologous transplant recipients were significantly older (median age 53 vs. 47 years, p < .01) and had a longer period between diagnosis and transplant (10.5 vs 7 months, p = .03). Autologous transplant led to lower transplant related mortality (TRM) of 4% (95% CI 0–36%) vs. 18% (0–9%) in the allogeneic patients at 100 days post transplant (p = .02). More frequent complete responses (CR) were seen in the allogeneic patients (64% (95% CI 37–91%) vs. 34% (95% CI 23–45%) in the autologous patients, p = .09). In the autologous patients, overall survival of 86% (95% CI 80–95%) at one year and 50% (95% CI 47–75%) at 4 years was seen vs. 64% (95% CI 40–87%) at one year and at 4 years in the allogeneic patients. In patients surviving beyond one year, survival was superior in the allogeneic transplant patients (100% (95% CI 100–100%) versus 58% (95% CI 41–75%) at 4 years, p = .02). The cumulative incidence of relapse showed a trend towards higher relapse in the autologous patients (73% (95% CI 55–90%) versus (37% (95% CI 11–63%) in allogeneic patients at 4 years, p = .1). In multiple regression analysis, attainment of a CR or PR pre transplant (OR 3.4, 95% CI 0.9–12.9, p = .06), ≤ 1 year between diagnosis and transplant (OR 3.8, 95% CI 1.1–13.8, p = .04), ≤ 2 regimens of chemotherapy (OR 8.3, 95% CI 2.2–31.3, p <.01) were associated with good response. Early transplant with ≤ 4 chemo cycles (RR of failure 0.5 (95% CI 0.2–0.9, p = 0.04) and attainment of CR or PR post transplant (RR 0.4 (95% CI 0.2–0.7, p < 0.01) was a significant predictor of good overall and progression free survival. Older age at transplant (RR 1.1, 95% CI 0.9–1.3, p = .06), allogeneic transplant (RR 11.0, 95% CI 2.3–53.7, p < .01), and > 4 cycles of pretransplant chemotherapy (RR 6.3, 95% CI 1.1–35.7, p = .04) were each significant predictors of high TRM. We observed good clinical tolerance of the myeloablative conditioning regimen followed by either autologous or allogeneic transplant. We report modest TRM, high CR rates and favorable survival following allogeneic transplants. Younger patients with responsive disease undergoing early transplant may have a superior survival and lower TRM. This group may be suitable candidates for allogeneic transplant.