Impact of Graft-Versus-Host Disease on Relapse and Nonrelapse Mortality Following Posttransplant Cyclophosphamide-Based Transplantation.

Following conventional graft-versus-host disease (GVHD) prophylaxis, the development of acute and/or chronic GVHD is associated with lower relapse rates. However, the effects of GVHD on relapse and non-relapse mortality following post-transplant cyclophosphamide (PTCy)-based GVHD prophylaxis have not been well studied. To this end, we analyzed the impact of acute and chronic GVHD following PTCy-based haploidentical donor transplantation (HIDT). The analysis included 335 consecutive HIDT recipients transplanted at a single institution between 2005 and 2021. Landmark analysis (LA) and time-dependent multivariable analysis (MVA) were utilized to study the impact of GVHD development on transplant outcome. Landmarks were defined as Day +100 for acute GVHD and one-year for chronic GVHD. Recipient characteristics included a median age of 50 (19-80) years, most commonly transplanted for acute leukemia[/MDS [242]. PBSC was the graft source in 81%, and regimen intensity was myeloablative in 49%. Median follow-up was 65 (23-207) months. In landmark analysis, development of grade 3 to 4 acute GVHD (versus 0-1) was associated with inferior 3-year overall survival (OS 47% versus 64%, P = .041), due to higher NRM (25% versus 10%, P = .013). In contrast, development of grade 2 acute GVHD had no significant effect on NRM or survival. When restricted to acute leukemia/MDS patients, development of grade II acute GVHD was associated with improved OS (79% versus 58%, P = .027) and a trend towards lower relapse (24% versus 36%, P = .08). Development of moderate-to-severe chronic GVHD resulted in significantly higher NRM (15% versus 4%, P = .010), but had no impact on relapse, DFS or OS. In Cox multivariate analysis (MVA), grade 3 to 4 acute GVHD and moderate-to-severe chronic GVHD were both associated with significantly higher NRM (HR 3.38, P < .001 and HR3.35, P < .001, respectively). In addition, grade 3 to 4 acute GVHD predicted worse OS (HR 1.80, P = .007) and DFS (HR 1.55, P = .041). In contrast, relapse was not impacted by acute or chronic GVHD in MVA. Grade 2 acute GVHD was not associated with transplant outcome in MVA. In summary, both grade 3 to 4 acute and moderate-to-severe chronic GVHD were associated with higher NRM after PTCy-based HIDT, without an effect on relapse risk. Methods of early identification of such patients in order to augment GVHD prophylaxis are clearly needed.

Immunosuppression-Free Status at 1 Year after Haploidentical Hematopoietic Cell Transplantation with Post-Transplantation Cyclophosphamide.

The development of chronic graft-versus-host disease (GVHD) in 1-year survivors after matched related or unrelated hematopoietic cell transplantation was shown to be associated with higher nonrelapse mortality (NRM) and worse overall survival (OS). The impact of chronic GVHD requiring immunosuppression (IS) for recipients of haploidentical transplantation (HIDT) with post-transplantation cyclophosphamide (PTCy) who have survived to 1 year post-transplantation has not been studied previously and was investigated for this analysis. A total of 322 adult patients who underwent HIDT at our center were included in this study. The effect of IS-free status on post-transplantation outcomes was assessed. The median follow-up for survivors was 63.9 months (range, 18.3 to 165 months). A total of 163 patients (65%) were IS-free at 1 year post-HIDT. Baseline characteristics of this group were similar to those of patients still requiring IS, except for higher percentages of female donor-male recipient pairs (28% versus 15%; P =.03) and female donors (48% versus 30%; P =.008). Logistic regression to identify patients more likely to be on IS at 1 year post-HIDT identified the use of a female donor as a significant risk factor (odds ratio, 2.11; P = .009). In a Cox regression analysis, patients requiring IS at 1 year post-transplantation had higher NRM (hazard ratio [HR], 4.18; 95% confidence interval [CI], 1.80 to 6.72; P < .001) and showed a trend toward worse disease-free survival (DFS) (HR, 1.59; 95% CI, .95 to 2.66; P =.08), with no impact on OS (HR, 1.44; 95% CI, .90 to 2.31; P = .13) or relapse (HR, .77; 95% CI, .37 to 1.61; P = .49). These results indicate that use of a female donor is a significant risk factor for requiring IS at 1 year post-HIDT. Additionally, chronic GVHD requiring IS at 1-year post-HIDT no significant effect on relapse but is associated with higher NRM and a trend toward worse DFS.

Revised HLA-DP TCE-Core Permissiveness Model Better Defines Relapse Risk and Survival following Haploidentical Transplant.

The presence of an HLA-DPB1 nonpermissive mismatch (NPMM) by the TCE-3 model has been associated with improved survival following haploidentical donor transplantation (HIDT) using post-transplantation cyclophosphamide (PTCy). With the development of a revised model (TCE-Core) that further separates TCE-3 "group 3" alleles into "core" (C) and "noncore" (NC) alleles, a formerly permissive mismatch (PMM) resulting from group 3 alleles in both donor and recipient is now considered a C-NPMM if 1 or more of those alleles is NC. We aimed to study the additional effect of HLA-DPB1 C-NPMM according to the TCE-Core algorithm, as well as the directional vector of the mismatch, on outcomes following HIDT. To this end, we analyzed 242 consecutive HIDT recipients with acute leukemia or myelodysplastic syndrome who underwent transplantation between 2005 and 2021 (median age, 51 years; range, 19 to 80 years). The median follow-up was 62 months (range, 23 to 199 months). Of the 136 HIDTs classified as PMM by TCE-3, 73 were reclassified as a C-NPMM by the TCE-Core algorithm, of which 36 were in the graft-versus host (GVH) vector (37 were host-versus-graft [HVG] only). Given comparable survival between conventional NPMM and C-NPMM, GVH/bidirectional were analyzed together (nonpermissive). HVG-only C-NPMM were combined with HLA-DPB1-matched and PMM (permissive) because of similar outcomes. The presence of a TCE-Core-defined nonpermissive HLA-DP mismatch resulted in superior 5-year overall survival (OS) (66% versus 47%) and disease-free survival (DFS) (60% versus 43%). Compared to the conventional TCE-3 algorithm, TCE-Core identified a higher percentage of nonpermissive transplants (38% versus 23%) and better discriminated outcomes between nonpermissive and permissive status, with a larger difference in survival outcomes using TCE-Core compared to TCE-3 (OS Δ, 18.3% versus 12.7%; DFS Δ, 16.5% versus 8.5%). In multivariable analysis (MVA), a nonpermissive TCE-Core mismatch led to improved OS (hazard ratio [HR], .54; P = .003) and DFS (HR, .62; P = .013), largely due to decreased relapse risk (HR, .63; P = .049). In contrast, nonrelapse mortality (NRM) and graft-versus-host disease (GVHD) outcomes were not significantly impacted. In summary, the presence of nonpermissive TCE-Core HLA-DP mismatch strongly predicts survival following PTCy-based HIDT, owing to a reduction in relapse risk without a corresponding increase in GVHD or NRM. As a donor selection tool, TCE-Core appears to better discriminate HIDT outcomes while at the same time identifying a larger percentage of the potential donor pool.

HLA evolutionary divergence (HED) informs the effect of HLA-B mismatch on outcomes after haploidentical transplantation.

Graft versus tumor relies on tumor-associated antigens (TAAs) that are presented to donor T cells via human leukocyte antigens (HLAs). The HLA evolutionary divergence (HED) between alleles of a single individual can dictate the ability to present TAAs. The impact of HED in haploidentical donor transplantation (HIDT) has not been studied. We studied the effect of HED on transplant outcomes following HIDT. We analyzed 322 consecutive recipient/donor pairs with a median follow-up of 57.2 months. Pairwise divergence of HLA class I and II showed that HLA-B, -DRB1, and -DQB1 contributing most to mean HED. The mean HED was class I 6.85 (HLA-A 7.08, -B 8.24, and -C 5.07), class II 8.58 (HLA-DRB1 10.97, -DQB1 10.06 and -DPB1 4.06). A high HED in class I mismatched recipient/donor haplotype (RD MM) was significant for worse DFS (HR 1.11, p = 0.020), and relapse (HR 1.11, p = 0.02). Also, a high HED in RD MM HLA-B haplotype had worse OS (HR 1.07, p = 0.02), DFS (HR 1.09, p = 0.002), higher relapse (HR 1.10, p = 0.003), and similar NRM to low HED. The multivariate analysis showed that high HED in RD MM HLA-B (≥7.8 vs <7.8) had worse DFS (HR 1.53, p = 0.01), higher relapse (HR 1.61, p = 0.024), and similar NRM and OS.

Gilteritinib as Post-Transplant Maintenance for AML With Internal Tandem Duplication Mutation of FLT3.

PURPOSE: Allogeneic hematopoietic cell transplantation (HCT) improves outcomes for patients with AML harboring an internal tandem duplication mutation of FLT3 (FLT3-ITD) AML. These patients are routinely treated with a FLT3 inhibitor after HCT, but there is limited evidence to support this. Accordingly, we conducted a randomized trial of post-HCT maintenance with the FLT3 inhibitor gilteritinib (ClinicalTrials.gov identifier: NCT02997202) to determine if all such patients benefit or if detection of measurable residual disease (MRD) could identify those who might benefit. METHODS: Adults with FLT3-ITD AML in first remission underwent HCT and were randomly assigned to placebo or 120 mg once daily gilteritinib for 24 months after HCT. The primary end point was relapse-free survival (RFS). Secondary end points included overall survival (OS) and the effect of MRD pre- and post-HCT on RFS and OS. RESULTS: Three hundred fifty-six participants were randomly assigned post-HCT to receive gilteritinib or placebo. Although RFS was higher in the gilteritinib arm, the difference was not statistically significant (hazard ratio [HR], 0.679 [95% CI, 0.459 to 1.005]; two-sided P = .0518). However, 50.5% of participants had MRD detectable pre- or post-HCT, and, in a prespecified subgroup analysis, gilteritinib was beneficial in this population (HR, 0.515 [95% CI, 0.316 to 0.838]; P = .0065). Those without detectable MRD showed no benefit (HR, 1.213 [95% CI, 0.616 to 2.387]; P = .575). CONCLUSION: Although the overall improvement in RFS was not statistically significant, RFS was higher for participants with detectable FLT3-ITD MRD pre- or post-HCT who received gilteritinib treatment. To our knowledge, these data are among the first to support the effectiveness of MRD-based post-HCT therapy.

Impact of Prior Inotuzumab Ozogamicin Treatment on Brexucabtagene Autoleucel outcomes in Adults with B-cell ALL.

The effect of prior inotuzumab ozogamicin (InO) treatment on brexucabtagene autoleucel (brexu-cel) outcomes remains unclear in adults with acute lymphoblastic leukemia (ALL), particularly the influence off previous InO response and the timing of administration. We conducted a retrospective multicenter analysis of 189 patients with relapsed/refractory (r/r) ALL treated with brexu-cel. Over half of the patients received InO before brexu-cel (InO-exposed). InO-exposed patients were more heavily pretreated (p= 0.02) and frequently had active marrow disease pre-apheresis (p= 0.03). Response rate and toxicity profile following brexu-cel were comparable for InO-exposed and InO-naïve; however, consolidation therapy post brexu-cel response was utilized at a higher rate in InO-naïve patients (p= 0.005). With a median follow up of 11.4 months, InO-exposed patients had inferior progression-free survival (PFS) (p=0.013) and overall survival (OS) (p=0.006) in univariate analyses; however, prior InO exposure did not influence PFS (HR 1.20, 95%CI, 0.71-2.03) in multivariate models. When InO-exposed patients were stratified according to prior InO response, InO responders had superior PFS (p=0.002) and OS (p<0.0001) relative to InO-refractory. The timing of administering InO did not affect brexu-cel outcomes, with comparable PFS (p=0.51) and OS (p=0.86) for patients receiving InO as bridging therapy or pre-apheresis. In conclusion, while InO exposure was associated with inferior survival outcomes following brexu-cel in unadjusted analyses, these associations were no longer significant in multivariate analyses, suggesting it is unlikely that InO negatively impacts brexu-cel efficacy. Our data instead imply that InO-exposed recipients of brexu-cel tend to be higher-risk patients with intrinsic adverse leukemia biology.