High CD34-positive cell dose in matched unrelated donor allogeneic hematopoietic stem cell transplant is not associated with graft-versus-host disease or mortality.

BACKGROUND: CD34+ stem cells serve as the primary graft source for allogeneic transplants, with a minimum of 2-4 × 106 cells/kg needed for engraftment. There are conflicting data on outcomes at high stem cell doses, with studies limited by few patients receiving doses far above the minimum target. STUDY DESIGN AND METHODS: In this retrospective, single-center study of patients with hematologic malignancies who underwent matched unrelated donor transplants, we assessed outcomes for engraftment, survival, relapse, and graft-versus-host disease (GVHD) for the highest CD34+ dose quintile (>13 × 106 cells/kg, n = 36) compared to the remaining patients (n = 139). Similar analysis was performed correlating T cell dose and outcomes. RESULTS: There was no difference between the groups in neutrophil engraftment, with a trend toward faster platelet engraftment. There was no significant difference in mortality (adjusted risk ratio [aRR] = 1.02, 95% confidence interval [CI] = 0.85-1.22), relapse (aRR = 1.10, 95% CI = 0.85-1.42), or overall survival by Kaplan-Meier analysis (p = .44). High CD34+ dose was not associated with higher incidence of acute GVHD (aRR = 0.99 grades II-IV, aRR = 1.18 grades III-IV) or chronic GVHD (aRR = 0.87 overall, RR = 1.21 severe). There was limited correlation between CD34+ and T cell dose (R2 = .073), and there was no significant difference in survival, relapse, or GVHD in the highest T cell dose quintile (n = 33) compared to the remaining quintiles (n = 132). DISCUSSION: We found no difference in survival, relapse, or GVHD incidence or severity in patients receiving CD34+ doses above prior cutoffs reported in the literature. These data do not support the routine use of graft CD34+ dose reduction.

Final analysis of a phase II trial of daratumumab, carfilzomib, lenalidomide, and dexamethasone in newly diagnosed multiple myeloma without transplant.

We evaluated the efficacy and safety of 24 cycles of Dara in combination with carfilzomib (K), lenalidomide (R), and dexamethasone (d) without autologous stem cell transplant (ASCT) in newly diagnosed multiple myeloma (NDMM) irrespective of ASCT eligibility in a single-arm, phase II study. The primary endpoint was the rate of stringent complete response (sCR) and/or measurable residual disease (MRD) < 10-5 by next-generation sequencing (NGS) at the end of cycle 8 (C8). MRD was also assessed on peripheral blood samples using both the EXENT® system and liquid chromatography-mass spectrometry (LC-MS). Forty-two patients entered the treatment phase; forty were evaluable for the primary endpoint. The rate of sCR and/or MRD < 10-5 following C8 was 30/40 (75%), meeting the statistical threshold for efficacy. The 10-6 MRD negative rate improved with treatment beyond C8. Agreement between EXENT® and NGS was high and increased over time; agreement between LC-MS and NGS was lower. The estimated 3-year progression-free survival progression-free survival was 85%, and 3-year overall survival was 95%. Upper respiratory infections occurred in 67% (7% grade 3-4). There were no treatment-related deaths. Extended frontline Dara-KRd induced a high rate of sCR and/or MRD negativity; the rate and depth of MRD negativity improved beyond C8.