Efficacy of minimal residual disease driven immune-intervention after allogeneic hematopoietic stem cell transplantation for high-risk chronic lymphocytic leukemia: results of a prospective multicenter trial.

Allogeneic hematopoietic stem cell transplantation (HSCT) remains a potentially curative and useful strategy in high-risk relapsing CLL. Minimal Residual Disease (MRD) assessment at 12 months post-HSCT is predictive of relapse. This phase 2 study aimed to achieve M12 MRD negativity (MRDneg) using MRD-driven immune-intervention (Md-PII) algorithm based on serial flow-cytometry blood MRD, involving cyclosporine tapering followed if failure by donor lymphocytes infusions. Patients had high-risk CLL according to 2006 EBMT consensus, in complete or partial response with lymphadenopathy < 5 cm and comorbidity score ≤ 2. Donors were HLA-matched sibling or matched unrelated (10/10). Forty-two enrolled patients with either 17p deletion (front-line, n=11; relapse n=16) or other high-risk relapse (n=15) received reduced intensity-conditioning regimen before HSCT and were submitted to Md-PII. M12-MRDneg status was achieved in 64% versus 14.2% before HSCT. With a median follow-up of 36 months (range, 19-53), 3-year overall survival, non-relapse mortality and cumulative incidence of relapse are 86.9% (95%CI, 70.8-94.4), 9.5% (95%CI, 3.7-23.4) and 29.6% (95%CI, 17.3-47.7). Incidence of 2-year limited and extensive chronic graft versus host disease (cGVHD) is 38% (95%CI, 23-53) and 23% (95%CI, 10-36) including 2 cases post Md-PII. Fifteen patients converted to MRDneg either after CsA withdrawal (n=12) or after cGVHD (n=3). As a time-dependent variable, MRDneg achievement at any time-point correlates with reduced relapse (HR=0.14 [0.04-0.53], p=0.004) and improvement of both progression free (HR=0.18 [0.06-0.6], p<0.005) and overall (HR: 0.18 [0.03-0.98], p=0.047) survival. These data highlight the value of MRD-driven immune-intervention to induce prompt MRD clearance in the therapy of CLL.

Checkpoint inhibition before haploidentical transplantation with posttransplant cyclophosphamide in Hodgkin lymphoma.

We report on 59 Hodgkin lymphoma patients undergoing haploidentical stem cell transplantation (SCT; haplo-SCT) with posttransplant cyclophosphamide (PTCy) as graft-versus-host disease (GVHD) prophylaxis, comparing outcomes based on pretransplant exposure to checkpoint inhibitors (CPIs). Considering pretransplant characteristics, the 2 cohorts (CPI = 29 patients vs no-CPI = 30 patients) were similar, except for the number of prior lines of therapy (6 vs 4; P < .001). With a median follow-up of 26 months (range, 7.5-55 months), by univariate analysis, the 100-day cumulative incidence of grade 2-4 acute GVHD was 41% in the CPI group vs 33% in the no-CPI group (P = .456), whereas the 1-year cumulative incidence of moderate to severe chronic GVHD was 7% vs 8%, respectively (P = .673). In the CPI cohort, the 2-year cumulative incidence of relapse appeared lower compared with the no-CPI cohort (0 vs 20%; P = .054). No differences were observed in terms of overall survival (OS), progression-free survival (PFS), and nonrelapse mortality (NRM) (at 2 years, 77% vs 71% [P = .599], 78% vs 53% [P = .066], and 15% vs 21% [P = .578], respectively). By multivariable analysis, CPI before SCT was an independent protective factor for PFS (hazard ratio [HR], 0.32; P = .037). Stable disease (SD)/progressive disease (PD) was an independent negative prognostic factor for both OS and PFS (HR, 14.3; P < .001 and HR, 14.1; P < .001, respectively) . In conclusion, CPI as a bridge to haplo-SCT seems to improve PFS, with no impact on toxicity profile.