Partial T-cell depletion improves the composite endpoint graft-versus-host disease-free, relapse-free survival after allogeneic hematopoietic stem cell transplantation

Evaluation of Disease Risk Comorbidity Index after Allogeneic Stem Cell Transplantation in a Cohort with Patients Undergoing Transplantation with In Vitro Partially T Cell Depleted Grafts

Outcomes of hematopoietic stem cell transplantation (HSCT) are influenced by comorbidities, disease type, and status at transplantation. Several prognostic scores can be used, such as the disease risk index (DRI) or the hematopoietic cell transplantation-specific comorbidity index (HCT-CI). Recently, a new prognostic tool, the disease risk comorbidity index (DRCI), combining the DRI and the HCT-CI, was published. The DRCI determines 6 patient groups (very low risk [VLR], low risk [LR], intermediate risk 1 [IR-1], intermediate risk 2 [IR-2], high risk [HiR], and very high risk [VHR]) with a significant predictive value for overall survival (OS), disease-free survival (DFS), relapse incidence (RI), and graft-versus-host disease-free/relapse-free survival (GRFS). However, the DRCI has not been evaluated for patients allografted with partially in vitro T cell depleted (pTDEP) grafts. In our center, we offer pTDEP to reduce graft-versus-host disease for patients in complete remission at transplant time. In this retrospective study, we investigated the DRCI in 404 adult patients (including 37.6% pTDEP) undergoing a first HSCT for hematological malignancies from 2008 to 2018. Because of the small number of patients in LR, VLR and LR were combined for analysis. In the entire cohort, 2-year OS was 84.4% (95% CI, 71.6% to 97.2%) for LR, 61.6% (54.8% to 68.4%) for IR-1, 45.7% (33.3% to 58.1%) for IR-2, 31% (19.4% to 42.6%) for HiR, and 30.9% (14.5% to 47.3%) for VHR (P < .001). In addition, the DRCI was predictive of DFS, RI, and GRFS but not of nonrelapsed mortality and graft-versus-host disease. Our study confirms similar results with the original publication but gives less accurate prognosis information than the DRI and HCT-CI when used separately. In conclusion, the DRCI does not seem to offer more relevant information than the DRI and HCT-CI to help physicians and patients for the HSCT decision.

Dynamic Graft-versus-Host Disease-Free, Relapse-Free Survival: Multistate Modeling of the Morbidity and Mortality of Allotransplantation

Graft-versus-host disease (GVHD)-free, relapse-free survival (GRFS) represents complete, ideal recovery after allogeneic hematopoietic cell transplantation (HCT). However, as originally proposed, this composite endpoint does not account for the possibility that HCT complications may improve after treatment. To more accurately estimate survival with response to GVHD and relapse after HCT, we developed a dynamic multistate GRFS (dGRFS) model with outcomes data from 949 patients undergoing their first allogeneic HCT for hematologic malignancy at the University of Minnesota. Because some patients were successfully treated for GVHD and relapse, dGRFS was higher than the originally defined time-to-event GRFS at 1 year (37.0 versus 27.6%) through 4 years (37.4% versus 22.2%). Mean survival without failure events was .52 years (95% confidence interval, .45 to .58 year) greater in dGRFS compared with the originally defined GRFS. Patient age (P< .001), disease risk (P < .001), conditioning intensity (P = .007), and donor type (P = .003) all significantly influenced dGRFS. The multistate model of dGRFS closely estimates the continuing and prevalent severe morbidity and mortality of allogeneic HCT. To serve the greater HCT community in more accurately modeling recovery from transplantation, we provide our R code for determination of dGRFS with annotations in Supplementary Materials.

Assessment of Individual versus Composite Endpoints of Acute Graft-versus-Host Disease in Determining Long-Term Survival after Allogeneic Transplantation

The overall composite of graft-versus-host disease (GVHD)-free, relapse-free survival (GRFS), defined as survival free of grade III-IV acute GVHD (aGVHD), chronic GVHD (cGVHD) requiring systemic immunosuppressive therapy (IST), or relapse, has emerged as a useful composite in clinical trials and to capture clinically meaningful events that impact quantity and quality of survival after allogeneic hematopoietic cell transplantation (HCT). We reviewed 565 consecutive patients aged ≥18 years undergoing HCT for hematologic malignancy to analyze how baseline incidence, specifics of clinical definitions, and proposed reductions in any one individual event may dynamically alter the overall performance of the composite To determine the relative impact of each GRFS event (excluding death), we accounted for competing risks using Fine and Gray methods, and correlated each event with overall survival (OS) using Kaplan-Meier methods. The consequences of modulating individual or composite endpoints on OS, such as hypothesized reductions of events of an HCT interventional trial, were examined using Monte Carlo simulations. The median age of the cohort was 54 years (range, 18 to 73 years). The majority of patients received HLA-matched unrelated donor HCT (53%), consisting of peripheral blood stem cell grafts (90%) after myeloablative conditioning (68%). Relapse conferred the greatest risk for death (hazard ratio [HR], 7.89; 95% confidence interval [CI], 5.83 to 10.69), followed by grade III-IV aGVHD (HR, 6.16; 95% CI, 4.42 to 8.56) and cGVHD requiring IST (HR, 1.69; 95% CI, 1.16 to 2.46). The overall GRFS composite correlated with an HR of 4.81 (95% CI, 3.61 to 6.41), which was lower compared with either relapse or grade III-IV aGVHD. Statistical simulations found that modulating the combined risk of both relapse and grade III-IV aGVHD predicted the greatest change in 5-year OS. These simulations suggest that GRFS as currently defined may be less optimal for correlating with OS, and further refinement of composite endpoints is needed. Nonetheless, composite endpoints may be particularly helpful in mitigating potential difficulties in interpretation when competing risks are present, most commonly seen in HCT studies.