Age barriers in allogeneic hematopoietic cell transplantation: Raising the silver curtain

Allogeneic hematopoietic cell transplantation (HCT) is no longer exclusively for the young. With an aging population, development of non-intensive remission-inducing strategies for hematologic malignancies, and novel graft-versus-host disease-prevention platforms, an older population of patients is pursuing HCT. The evolving population of HCT recipients requires an overhaul in the way we risk-stratify and optimize patients prior to HCT. Here, we review the history and current state of HCT for older adults and propose an assessment and intervention flow to bridge the gaps in today's clinical guidelines.

ASTCT Committee on Practice Guidelines Survey on Evaluation and Management of Relapsed/Refractory Multiple Myeloma after Failure of Chimeric Antigen Receptor T Cell Therapy

Chimeric antigen receptor T cell therapy (CAR-T) has revolutionized the management of relapsed and/or refractory multiple myeloma (RRMM). However, CAR-T treatment failure is not uncommon and remains a major therapeutic challenge. There is substantial variability across transplantation and cellular therapy programs in assessing and managing post-CAR-T failures in patients with RRMM. The American Society for Transplantation and Cellular Therapy (ASTCT) Committee on Practice Guidelines conducted an online cross-sectional survey between September 2023 and December 2023 to determine myeloma, transplantation, and cellular therapy physicians' practice patterns for the surveillance, diagnosis, and management of CAR-T failure. The intent of this survey was to understand clinical practice patterns and identify areas for further investigation. Email surveys were sent to 1311 ASTCT physician members, of whom 80 (6.1%) completed the survey. The respondents were 58% white and 66% male, and 51% had >10 years of clinical experience. Most (89%) respondents were affiliated with a university/teaching center, and 56% had a myeloma-focused transplantation and/or cellular therapy practice. Post-CAR-T surveillance laboratory studies were commonly done every 4 weeks, and surveillance bone marrow biopsies and/or imaging surveillance were most commonly done at 3 months. Sixty-four percent of the respondents would often or always consider biopsy or imaging to confirm relapse. The most popular post-CAR-T failure rescue regimen was GPRC5D-directed immunotherapy (30%) for relapses occurring ≤3 months and BCMA-directed bispecific therapies (32.5%) for relapse at >3 months. Forty-one percent of the respondents endorsed post-CAR-T prolonged cytopenia as being "often" or "always" a barrier to next-line therapy; 53% had offered stem cell boost as a mitigation approach. Substantial across-center variation in practice patterns raises the need for collaborative studies and expert clinical recommendations to describe best practices for post-CAR-T disease surveillance, optimal workup for treatment failure, and choice of rescue therapies.

Three-year follow-up analysis of axicabtagene ciloleucel in relapsed/refractory indolent non-Hodgkin lymphoma (ZUMA-5)

ABSTRACT

Axicabtagene ciloleucel (axi-cel) is an autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy approved for relapsed/refractory (R/R) follicular lymphoma (FL). Approval was supported by the phase 2, multicenter, single-arm ZUMA-5 study of axi-cel for patients with R/R indolent non-Hodgkin lymphoma (iNHL; N = 104), including FL and marginal zone lymphoma (MZL). In the primary analysis (median follow-up, 17.5 months), the overall response rate (ORR) was 92% (complete response rate, 74%). Here, we report long-term outcomes from ZUMA-5. Eligible patients with R/R iNHL after ≥2 lines of therapy underwent leukapheresis, followed by lymphodepleting chemotherapy and axi-cel infusion (2 × 106 CAR T cells per kg). The primary end point was ORR, assessed in this analysis by investigators in all enrolled patients (intent-to-treat). After median follow-up of 41.7 months in FL (n = 127) and 31.8 months in MZL (n = 31), ORR was comparable with that of the primary analysis (FL, 94%; MZL, 77%). Median progression-free survival was 40.2 months in FL and not reached in MZL. Medians of overall survival were not reached in either disease type. Grade ≥3 adverse events of interest that occurred after the prior analyses were largely in recently treated patients. Clinical and pharmacokinetic outcomes correlated negatively with recent exposure to bendamustine and high metabolic tumor volume. After 3 years of follow-up in ZUMA-5, axi-cel demonstrated continued durable responses, with very few relapses beyond 2 years, and manageable safety in patients with R/R iNHL. The ZUMA-5 study was registered at www.clinicaltrials.gov as #NCT03105336.

Post-transplantation cyclophosphamide is associated with increased bacterial infections

Post-transplant cyclophosphamide (PTCy) is increasingly used to reduce graft-versus-host disease after hematopoietic cell transplantation (HCT); however, it might be associated with more infections. All patients who were ≥2 years old, receiving haploidentical or matched sibling donor (Sib) HCT for acute leukemias or myelodysplastic syndrome, and either calcineurin inhibitor (CNI)- or PTCy-based GVHD prophylaxis [Haploidentical HCT with PTCy (HaploCy), 757; Sibling with PTCy (SibCy), 403; Sibling with CNI-based (SibCNI), 1605] were included. Most bacterial infections occurred within the first 100 days; 953 patients (34.5%) had at least 1 infection and 352 patients (13%) had ≥2 infections. Patients receiving PTCy had a greater incidence of bacterial infections by day 180 [HaploCy 46%; SibCy 48%; SibCNI 35%; p < 0.001]. Compared with the SibCNI without infection cohort, 1.99-fold, 3.33-fold, 2.78-fold, and 2.53-fold increased TRM was seen for the HaploCy cohort without infection and HaploCy, SibCy, and SibCNI cohorts with infection, respectively. Bacterial infections increased mortality [HaploCy (HR1.84, 99% CI: 1.45-2.33, p < 0.0001), SibCy cohort (HR,1.68, 99% CI: 1.30-2.19, p < 0.0001), and SibCNI cohort (HR,1.76, 99% CI: 1.43-2.16, p < 0.0001). PTCy was associated with increased bacterial infections regardless of donor, and bacterial infections were associated with increased mortality irrespective of GVHD prophylaxis. Patients receiving PTCy should be monitored carefully for bacterial infections following PTCy.

Allogeneic hematopoietic cell transplantation for blastic plasmacytoid dendritic cell neoplasm: a CIBMTR analysis

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematological malignancy with a poor prognosis and considered incurable with conventional chemotherapy. Small observational studies reported allogeneic hematopoietic cell transplantation (allo-HCT) offers durable remissions in patients with BPDCN. We report an analysis of patients with BPDCN who received an allo-HCT, using data reported to the Center for International Blood and Marrow Transplant Research (CIBMTR). We identified 164 patients with BPDCN from 78 centers who underwent allo-HCT between 2007 and 2018. The 5-year overall survival (OS), disease-free survival (DFS), relapse, and nonrelapse mortality (NRM) rates were 51.2% (95% confidence interval [CI], 42.5-59.8), 44.4% (95% CI, 36.2-52.8), 32.2% (95% CI, 24.7-40.3), and 23.3% (95% CI, 16.9-30.4), respectively. Disease relapse was the most common cause of death. On multivariate analyses, age of ≥60 years was predictive for inferior OS (hazard ratio [HR], 2.16; 95% CI, 1.35-3.46; P = .001), and higher NRM (HR, 2.19; 95% CI, 1.13-4.22; P = .02). Remission status at time of allo-HCT (CR2/primary induction failure/relapse vs CR1) was predictive of inferior OS (HR, 1.87; 95% CI, 1.14-3.06; P = .01) and DFS (HR, 1.75; 95% CI, 1.11-2.76; P = .02). Use of myeloablative conditioning with total body irradiation (MAC-TBI) was predictive of improved DFS and reduced relapse risk. Allo-HCT is effective in providing durable remissions and long-term survival in BPDCN. Younger age and allo-HCT in CR1 predicted for improved survival, whereas MAC-TBI predicted for less relapse and improved DFS. Novel strategies incorporating allo-HCT are needed to further improve outcomes.

Impact of second primary malignancy post-autologous transplantation on outcomes of multiple myeloma: a CIBMTR analysis

The overall survival (OS) has improved significantly in multiple myeloma (MM) over the last decade with the use of proteasome inhibitor and immunomodulatory drug-based combinations, followed by high-dose melphalan and autologous hematopoietic stem cell transplantation (auto-HSCT) and subsequent maintenance therapies in eligible newly diagnosed patients. However, clinical trials using auto-HSCT followed by lenalidomide maintenance have shown an increased risk of second primary malignancies (SPM), including second hematological malignancies (SHM). We evaluated the impact of SPM and SHM on progression-free survival (PFS) and OS in patients with MM after auto-HSCT using CIBMTR registry data. Adult patients with MM who underwent first auto-HSCT in the United States with melphalan conditioning regimen from 2011 to 2018 and received maintenance therapy were included (n = 3948). At a median follow-up of 37 months, 175 (4%) patients developed SPM, including 112 (64%) solid, 36 (20%) myeloid, 24 (14%) SHM, not otherwise specified, and 3 (2%) lymphoid malignancies. Multivariate analysis demonstrated that SPM and SHM were associated with an inferior PFS (hazard ratio [HR] 2.62, P < .001 and HR 5.01, P < .001, respectively) and OS (HR 3.85, P < .001 and HR 8.13, P < .001, respectively). In patients who developed SPM and SHM, MM remained the most frequent primary cause of death (42% vs 30% and 53% vs 18%, respectively). We conclude the development of SPM and SHM leads to a poor survival in patients with MM and is an important survivorship challenge. Given the median survival for MM continues to improve, continued vigilance is needed to assess the risks of SPM and SHM with maintenance therapy post-auto-HSCT.

Autologous transplant vs chimeric antigen receptor T-cell therapy for relapsed DLBCL in partial remission

The relative efficacy of autologous hematopoietic cell transplant (auto-HCT) vs chimeric antigen receptor T-cell (CAR-T) therapy in patients with diffuse large B-cell lymphoma (DLBCL) who achieve a partial remission (PR) after salvage chemotherapy is not known. Using the Center for International Blood & Marrow Transplant Research registry database, we identified adult patients with DLBCL who received either an auto-HCT (2013-2019) or CAR-T treatment with axicabtagene ciloleucel (2018-2019) while in a PR by computed tomography or positron emission tomography scan. We compared the clinical outcomes between the 2 cohorts using univariable and multivariable regression models after adjustment for relevant baseline and clinical factors. In the univariable analysis, the 2-year progression-free survival (52% vs 42%; P = .1) and the rate of 100-day nonrelapse mortality (4% vs 2%; P = .3) were not different between the 2 cohorts, but consolidation with auto-HCT was associated with a lower rate of relapse/progression (40% vs 53%; P = .05) and a superior overall survival (OS) (69% vs 47%; P = .004) at 2 years. In the multivariable regression analysis, treatment with auto-HCT was associated with a significantly lower risk of relapse/progression rate (hazard ratio = 1.49; P = .01) and a superior OS (hazard ratio = 1.63; P = .008). In patients with DLBCL in a PR after salvage therapy, treatment with auto-HCT was associated with a lower incidence of relapse and a superior OS compared with CAR-T. These data support the role of auto-HCT as the standard of care in transplant-eligible patients with relapsed DLBCL in PR after salvage therapy.

Sustained Hematopoietic Engraftment Potential after Prolonged Storage of Cryopreserved Hematopoietic Stem Cells (HSC) Used in Salvage Autologous Stem Cell Transplantation: Prolonged Storage of HSCs Sustains Hematological Reconstitution Potential

BACKGROUND

Salvage autologous hematopoietic stem cell transplantation (HSCT) is an effective treatment for patients with relapsed multiple myeloma (MM). Peripheral blood stem cells (PBSCs), a source of hematopoietic stem cells (HSCs), are collected prior to first transplant and adequate quantities of PBSCs can be collected and stored potentially for years to support at least two transplants for eligible patients. To ensure the safety of salvage HSCT used in the treatment of patients in subsequent relapse, PBSCs must retain the potential to engraft even after several years of cryopreservation. Although PBSC viability has been extensively studied using in vitro techniques, few publications describe the most rigorous functional potency measure: of patients receiving a myeloablative conditioning regimen. This study describes a large single-institution experience evaluating the engraftment kinetics of PBSCs used in salvage transplantation after multiple years of storage in comparison to first transplantation of the same patients in the treatment of MM.

STUDY DESIGN AND METHODS

A retrospective chart review of patients with MM undergoing HSCT from 2000 to 2021, identified 89 patients who received salvage autologous PBSC stored > 1 year after first HSCT. PBSC were cryopreserved and stored in vapor-phase liquid nitrogen refrigerators at a temperature of ≤ -150°C. All patients received a PBSC product for both transplants from the same collection cycle. Differences in CD34⁺ cell doses and days to engraftment between the first and salvage transplant were tested using a paired 2-tailed t-test and Wilcoxon signed-rank test. Univariate and multivariable linear regressions were used to determine association between storage time and days to engraftment, adjusting for CD34+ cell dose and conditioning regimen in the multivariable model.

RESULTS

The median storage time between day of initial collection and salvage transplant was 5.4 years (range, 1.0 - 19.7). Engraftment kinetics demonstrated a sustained neutrophil engraftment (absolute neutrophil count (ANC) > 0.5 × 10⁹ cells/L) at a median of 11 days after both the first and salvage transplant (ranges, 8 - 15 and 8 - 19 respectively, p<0.05). The median time to sustained platelet engraftment (> 20 × 10⁹ cells/L without transfusion support) was 13.5 days after first HSCT and 14 days after salvage HSCT (ranges, 9 - 27 and 10 - 56 respectively, p = 0.616). After adjusting for CD34+ cell doses and conditioning regimens, there was no association between the duration of cryopreservation and days to neutrophil (r = 0.178, p = 0.130) or platelet (r = 0.244, p = 0.100) engraftments.

CONCLUSION

Engraftment kinetics of the salvage HSCT are comparable to the first HSCT even when products are stored in vapor-phase nitrogen refrigerators for a median time of 5.4 years. There is no association between storage duration and time to engraftment when controlling for CD34+ dose and conditioning regimens. Prolonged storage of cryopreserved HSC products is a safe practice for MM patients undergoing salvage autologous HSCT.

Outcomes of Allogeneic Hematopoietic Cell Transplantation in T-cell Prolymphocytic Leukemia: A Contemporary Analysis from the Center for International Blood and Marrow Transplant Research

T cell prolymphocytic leukemia (T-PLL) is a rare, aggressive malignancy with limited treatment options and poor long-term survival. Previous studies of allogeneic hematopoietic cell transplantation (alloHCT) for T-PLL are limited by small numbers, and descriptions of patient and transplantation characteristics and outcomes after alloHCT are sparse. In this study, we evaluated outcomes of alloHCT in patients with T-PLL and attempted to identify predictors of post-transplantation relapse and survival. We conducted an analysis of data using the Center for International Blood and Marrow Transplant Research database on 266 patients with T-PLL who underwent alloHCT between 2008 and 2018. The 4-year rates of overall survival (OS), disease-free survival (DFS), relapse, and treatment-related mortality (TRM) were 30.0% (95% confidence interval [CI], 23.8% to 36.5%), 25.7% (95% CI, 20% to 32%), 41.9% (95% CI, 35.5% to 48.4%), and 32.4% (95% CI, 26.4% to 38.6%), respectively. In multivariable analyses, 3 variables were associated with inferior OS: receipt of a myeloablative conditioning (MAC) regimen (hazard ratio [HR], 2.18; P < .0001), age >60 years (HR, 1.61; P = .0053), and suboptimal performance status, defined by Karnofsky Performance Status (KPS) <90 (HR, 1.53; P = .0073). Receipt of an MAC regimen also was associated with increased TRM (HR, 3.31; P < .0001), an elevated cumulative incidence of grade II-IV acute graft-versus-host disease (HR, 2.94; P = .0011), and inferior DFS (HR, 1.86; P = .0004). Conditioning intensity was not associated with relapse; however, stable disease/progression was correlated with increased risk of relapse (HR, 2.13; P = .0072). Both in vivo T cell depletion (TCD) as part of conditioning and KPS <90 were associated with worse TRM and inferior DFS. Receipt of total body irradiation had no significant effect on OS, DFS, or TRM. Our data show that reduced-intensity conditioning without in vivo TCD (ie, without antithymocyte globulin or alemtuzumab) before alloHCT was associated with long-term DFS in patients with T-PLL who were age ≤60 years or who had a KPS >90 or chemosensitive disease.

Subsequent Cancers in Patients Affected with Moderate or Severe Chronic Graft-versus-Host Disease

Subsequent cancer (SC) is a significant cause of morbidity and mortality in long-term survivors after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Chronic graft-versus-host disease (cGVHD) and treatment-related immunosuppression have been recognized as risk factors for SC. This study sought to investigate the incidence and risk factors for SC in patients with established cGVHD, assessed separately for onset of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC)-categorized into nonmelanoma skin cancer (NMSC)-and all cancers other than NMSC. Two hundred and four patients were enrolled in the prospective cross-sectional cGVHD Natural History Study and underwent comprehensive clinical evaluation. Patients were followed-up with an annual survey. The cumulative incidences of NMSC and cancers other than NMSC with competing risks were estimated separately, and transplantation- and cGVHD-related factors were assessed for association with outcomes using Gray's test and multivariable Cox models. The time period for all analyses began at 2 years postevaluation to restrict analyses to patients presumed to not have had SC present at evaluation. Nineteen patients were diagnosed with NMSC and 19 were diagnosed with cancers other than NMSC, with 10-year cumulative incidences of 15.5% (95% confidence interval, 9.0% to 27.6%) and 13.8% (95% CI, 8.2% to 20.8%), respectively. Age at transplantation (hazard ratio [HR], 1.94; 95% CI, 1.23 to 3.06) and higher C-reactive protein level at evaluation (HR, 9.49; 95% CI, 1.26 to 71.58) were jointly associated with NMSC, and gastrointestinal cGVHD at evaluation (HR, 0.26; 95% CI, 0.09 to 0.78) was associated with reduced risk of NMSC. T cell depletion at transplantation (HR, 3.09; 95% CI, 1.17 to 8.20), lymphoma as an indication for transplantation (HR, 3.96; 95% CI, 1.56 to 10.05), and oral cGVHD severity at evaluation (HR, 4.36; 95% CI, 1.52 to 12.46) were jointly associated with cancers other than NMSC. This study estimates the incidence of SC in a population of allo-HSCT recipients with severe cGVHD and identifies correlations with the subsequent development of SC. These factors seem to differ between NMSC and cancers other than NMSC. Further longitudinal investigations accounting for dynamic and cumulative processes are needed to improve our understanding and management of SC.

Planned Granulocyte Colony-Stimulating Factor Adversely Impacts Survival after Allogeneic Hematopoietic Cell Transplantation Performed with Thymoglobulin for Myeloid Malignancy

The in vivo depletion of recipient and donor T lymphocytes using antithymocyte globulin (ATG; Thymoglobulin) is widely adopted in allogeneic hematopoietic stem cell transplantation (HCT) to reduce the incidence of both graft failure and graft-versus-host disease (GVHD). However, excess toxicity to donor lymphocytes may hamper immune reconstitution, compromising antitumor effects and increasing infection. Granulocyte-colony stimulating factor (G-CSF) administered early after HCT may increase ATG-mediated lymphotoxicity. This study aimed to investigate the effect of an interaction between ATG and post-transplantation granulocyte colony-stimulating factor (G-CSF) on allogeneic HCT outcomes, using the Center for International Blood and Marrow Transplant Research (CIBMTR) registry. We studied patients age ≥18 years with acute myelogenous leukemia (AML) and myelodysplastic syndrome (MDS) who received Thymoglobulin-containing preparative regimens for HLA-matched sibling/unrelated or mismatched unrelated donor HCT between 2010 and 2018. The effect of planned G-CSF that was started between pretransplantation day 3 and post-transplantation day 12 was studied in comparison with transplantations that did not include G-CSF. Cox regression models were built to identify risk factors associated with outcomes at 1 year after transplantation. A total of 874 patients met the study eligibility criteria, of whom 459 (53%) received planned G-CSF. HCT with planned G-CSF was associated with a significantly increased risk for nonrelapse mortality (NRM) (hazard ratio [HR] 2.03; P <.0001; 21% versus 12%) compared to HCT without G-CSF. The 6-month incidence of viral infection was higher with G-CSF (56% versus 47%; P = .007), with a particular increase in Epstein-Barr virus infections (19% versus 11%; P = .002). The observed higher NRM with planned G-CSF led to lower overall survival (HR, 1.52; P = .0005; 61% versus 72%). There was no difference in GVHD risk between the treatment groups. We performed 2 subgroup analyses showing that our findings held true in patients age ≥50 years and in centers where G-CSF was used in some, but not all, patients. In allogeneic peripheral blood HCT performed with Thymoglobulin for AML and MDS, G-CSF administered early post-transplantation resulted in a 2-fold increase in NRM and a 10% absolute decrement in survival. The use of planned G-CSF in the early post-transplantation period should be carefully considered on an individual patient basis, weighing any perceived benefits against these risks.

American Society of Transplantation and Cellular Therapy, Center of International Blood and Marrow Transplant Research, and European Society for Blood and Marrow Transplantation Clinical Practice Recommendations for Transplantation and Cellular Therapies in Mantle Cell Lymphoma

Autologous (auto-) and allogeneic (allo-) hematopoietic cell transplantation (HCT) are accepted treatment modalities in contemporary treatment algorithms for mantle cell lymphoma (MCL). Chimeric antigen receptor (CAR) T cell therapy recently received approval for MCL; however, its exact place and sequence in relation to HCT remain unclear. The American Society of Transplantation and Cellular Therapy, Center of International Blood and Marrow Transplant Research, and the European Society for Blood and Marrow Transplantation jointly convened an expert panel to formulate consensus recommendations for role, timing, and sequencing of auto-HCT, allo-HCT, and CAR T cell therapy for patients with newly diagnosed and relapsed/refractory (R/R) MCL. The RAND-modified Delphi method was used to generate consensus statements. Seventeen consensus statements were generated, with a few key statements as follows: in the first line setting, auto-HCT consolidation represents standard of care in eligible patients, whereas there is no clear role of allo-HCT or CAR T cell therapy outside of clinical trials. In the R/R setting, the preferential option is CAR T cell therapy, especially in patients with MCL failing or intolerant to at least one Bruton's tyrosine kinase inhibitor, while allo-HCT is recommended if CAR T cell therapy fails or is infeasible. Several recommendations were based on expert opinion, where the panel developed consensus statements for important real-world clinical scenarios to guide clinical practice. In the absence of contemporary evidence-based data, the panel found RAND-modified Delphi methodology effective in providing a formal framework for developing consensus recommendations for the timing and sequence of cellular therapies for MCL.

ASTCT, CIBMTR, and EBMT clinical practice recommendations for transplant and cellular therapies in mantle cell lymphoma

Autologous (auto-) or allogeneic (allo-) hematopoietic cell transplantation (HCT) are accepted treatment modalities for mantle cell lymphoma (MCL). Recently, chimeric antigen receptor (CAR) T-cell therapy received approval for MCL; however, its exact place and sequence in relation to HCT is unclear. The ASTCT, CIBMTR, and the EBMT, jointly convened an expert panel to formulate consensus recommendations for role, timing, and sequencing of auto-, allo-HCT, and CAR T-cell therapy for patients with newly diagnosed and relapsed/refractory (R/R) MCL. The RAND-modified Delphi method was used to generate consensus statements. Seventeen consensus statements were generated; in the first-line setting auto-HCT consolidation represents standard-of-care in eligible patients, whereas there is no clear role of allo-HCT or CAR T-cell therapy, outside of a clinical trial. In the R/R setting, the preferential option is CAR T-cell therapy especially in MCL failing or intolerant to at least one Bruton's tyrosine kinase inhibitor, while allo-HCT is recommended if CAR T-cell therapy has failed or is not feasible. In the absence of contemporary evidence-based data, the panel found RAND-modified Delphi methodology effective in providing a formal framework for developing consensus recommendations for the timing and sequence of cellular therapies for MCL.

Outcomes of upfront autologous hematopoietic cell transplantation in patients with multiple myeloma who are 75 years old or older

BACKGROUND

Consolidative autologous hematopoietic stem cell transplantation (AHCT) is commonly used for patients with multiple myeloma (MM). We studied AHCT use and outcomes in patients with MM ≥75 years old.

METHODS

Patients with MM ≥75 years old receiving AHCT between 2013 and 2017 in the United States were identified using the Center for International Blood and Marrow Transplant Research database. Relapse and/or progression (REL), progression-free survival (PFS), and overall survival (OS) were modeled using Cox proportional hazards models. Covariates used were age, sex, Karnofsky performance score (KPS), HCT-comorbidity index (HCT-CI), International Staging System and/or Durie-Salmon stage, high-risk cytogenetics, melphalan dose, and disease status at and 1 year after transplant. AHCT utilization rate using the Surveillance, Epidemiology, and End Results database was used to estimate specific incidence among ≥75 years old by race and gender.

RESULTS

Of 360 patients, 63% were male, 84% were White, 56% had KPS <90, and 57% had HCT-CI ≥3. The 100-day transplant-related mortality was 1% (0%-2%) with a 2-year REL rate of 27% (95% confidence interval [CI], 22%-33%), PFS of 66% (95% CI, 60%-72%), and OS of 83% (95% CI, 78%-87%). On multivariate analysis, only high-risk cytogenetics was associated with REL risk and decreased PFS. In White males, transplant utilization rate was 5.2%-5.8% compared to 3.5%-4.0% in African American males (P = .02). There was 3.37-3.79% transplant utilization in White females compared to 1.88-2.12% in African American females (P < .01).

CONCLUSIONS

The use of AHCT was associated with excellent 2-year outcomes in this selected MM population ≥75 years old. Transplant utilization for patients ≥75 years old remains low with significant racial and gender disparities.

Outcomes Associated With Thiotepa-Based Conditioning in Patients With Primary Central Nervous System Lymphoma After Autologous Hematopoietic Cell Transplant

Importance

Primary central nervous system lymphoma (PCNSL) requires induction and consolidation to achieve potential cure. High-dose therapy and autologous hematopoietic cell transplant (AHCT) is an accepted and effective consolidation strategy for PCNSL, but no consensus exists on the optimal conditioning regimens.

Objective

To assess the outcomes in patients with PCNSL undergoing AHCT with the 3 most commonly used conditioning regimens: thiotepa/busulfan/cyclophosphamide (TBC), thiotepa/carmustine (TT-BCNU), and carmustine/etoposide/cytarabine/melphalan (BEAM).

Design, Setting, and Participants

This observational cohort study used registry data from the Center for International Blood and Marrow Transplant Research registry. The Center is a working group of more than 380 transplantation centers worldwide that contributed detailed data on HCT to a statistical center at the Medical College of Wisconsin, Milwaukee. The participant data were from 603 adult patients with PCNSL who underwent AHCT as initial, or subsequent, consolidation between January 2010 and December 2018. Patients were excluded if they had a non-Hodgkin lymphoma subtype other than diffuse large B-cell lymphoma, systemic non-Hodgkin lymphoma, or HIV; received an uncommon conditioning regimen; or were not in partial remission or complete remission prior to AHCT. Statistical analysis was performed from July 5, 2020, to March 1, 2021.

Interventions

Patients received 1 of 3 conditioning regimens: TBC (n = 263), TT-BCNU (n = 275), and BEAM (n = 65).

Main Outcomes and Measures

The primary outcome was progression-free survival. Secondary outcomes included hematopoietic recovery, incidence of relapse, nonrelapse mortality, and overall survival.

Results

Of 603 patients, the mean age was 57 (range, 19-77) years and 318 (53%) were male. The 3-year adjusted progression-free survival rates were higher in the TBC cohort (75%) and TT-BCNU cohort (76%) compared with the BEAM cohort (58%) (P = .03) owing to a higher relapse risk in the BEAM cohort (hazard ratio [HR], 4.34; 95% CI, 2.45-7.70; P < .001). In a multivariable regression analysis, compared with the TBC cohort, patients who received TT-BCNU had a higher relapse risk (HR, 1.79; 95% CI, 1.07-2.98; P = .03), lower risk of nonrelapse mortality (NRM) (HR, 0.50; 95% CI, 0.29-0.87; P = .01), and similar risk of all-cause mortality more than 6 months after HCT (HR, 1.54; 95% CI, 0.93-2.55; P = .10). Age of 60 years or older, Karnofsky performance status less than 90, and an HCT-comorbidity index greater than or equal to 3 were associated with lower rates of survival across all 3 cohorts. Subgroup analyses demonstrated that patients aged 60 years and older had considerably higher NRM with TBC.

Conclusions and Relevance

In this cohort study, thiotepa-based conditioning regimen was associated with higher rates of survival compared with BEAM, despite higher rates of early toxic effects and NRM; these findings may assist clinicians in choosing between TBC or TT-BCNU based on patient and disease characteristics.

Outcomes in ZUMA-5 with axicabtagene ciloleucel (axi-cel) in patients (pts) with relapsed/refractory (R/R) indolent non-Hodgkin lymphoma (iNHL) who had the high-risk feature of progression within 24 months from initiation of first anti-CD20–containing chemoimmunotherapy (POD24)

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Background: POD24 is an indicator of poor survival in iNHL (Casulo & Barr. Blood. 2019). In the ZUMA-5 Phase 2 study of axi-cel anti-CD19 CAR T-cell therapy in pts with R/R iNHL, overall response rates (ORR) after 17.5 months median follow-up were similarly high in those with and without POD24 (93% and 92%; Jacobson et al. ASH 2020. #700). Here, we report updated outcomes with longer follow-up in pts with POD24 in ZUMA-5. Methods: Adults with R/R follicular lymphoma (FL) or marginal zone lymphoma (MZL) after ≥2 lines of therapy underwent leukapheresis followed by conditioning therapy and axi-cel infusion (2×106 CAR T cells/kg). Axi-cel–treated pts with available data on progression after an anti-CD20 mAb + alkylating agent were included. The updated efficacy analysis occurred when ≥80 treated pts with FL had ≥18 months follow-up. Results: Of 129 pts at baseline, 81 pts (63%; 68 FL, 13 MZL) had POD24 and 48 pts (37%; 40 FL, 8 MZL) did not have POD24. Median prior lines of therapy in pts with and without POD24 were 3 and 3.5, respectively. High-risk characteristics of pts with and without POD24 included stage III/IV disease, 83% and 94%; ≥3 FLIPI, 44% and 43%; high tumor bulk (GELF), 51% and 44%; and refractory disease, 77% and 63%, respectively. With 23.3 months median follow-up, ORR among efficacy-evaluable pts with POD24 (n = 61) and without POD24 (n = 37) was 92% each (complete response rates, 75% and 86%). At data cutoff, 52% of pts with POD24 and 70% without POD24 had ongoing responses. Median duration of response, progression-free survival, and overall survival were not reached in pts with and without POD24; 18-month estimated rates were 60% and 78%, 55% and 84%, and 85% and 94%, respectively. Incidences of Grade ≥3 adverse events were similar in pts with and without POD24 (84% and 88%), including cytopenias (69% and 65%) and infections (15% and 21%). Grade ≥3 cytokine release syndrome (CRS) occurred in 9% and 2% of pts with and without POD24, respectively; Grade ≥3 neurologic events (NEs) occurred in 17% of pts each. Median times to onset were similar in pts with and without POD24 for CRS (4 days each) and NEs (8 days and 7 days); median durations of CRS (7 days and 5 days) and NEs (11 days and 13 days) were also similar between groups. In efficacy-evaluable pts with FL, median peak CAR T-cell levels were similar in pts with and without POD24 (35.8 cells/μL and 34.5 cells/μL). Peak levels of key inflammatory biomarkers and axi-cel product attributes were generally similar in pts with and without POD24. Conclusions: Axi-cel showed a high rate of durable responses in pts with POD24 iNHL, a population with high-risk disease. Efficacy results, as well as safety and pharmacological profiles, appeared largely comparable between groups, with the exception of PFS rates. Clinical trial information: NCT03105336.

Age no bar: A CIBMTR analysis of elderly patients undergoing autologous hematopoietic cell transplantation for multiple myeloma

BACKGROUND

Upfront autologous hematopoietic stem cell transplantation (AHCT) remains an important therapy in the management of patients with multiple myeloma (MM), a disease of older adults.

METHODS

The authors investigated the outcomes of AHCT in patients with MM who were aged ≥70 years. The Center for International Blood and Marrow Transplant Research (CIBMTR) database registered 15,999 patients with MM in the United States within 12 months of diagnosis during 2013 through 2017; a total of 2092 patients were aged ≥70 years. Nonrecurrence mortality (NRM), disease recurrence and/or progression (relapse; REL), progression-free survival (PFS), and overall survival (OS) were modeled using Cox proportional hazards models with age at transplantation as the main effect. Because of the large sample size, a P value <.01 was considered to be statistically significant a priori.

RESULTS

An increase in AHCT was noted in 2017 (28%) compared with 2013 (15%) among patients aged ≥70 years. Although approximately 82% of patients received melphalan (Mel) at a dose of 200 mg/m² overall, 58% of the patients aged ≥70 years received Mel at a dose of 140 mg/m² . On multivariate analysis, patients aged ≥70 years demonstrated no difference with regard to NRM (hazard ratio [HR] 1.3; 99% confidence interval [99% CI], 1-1.7 [P = .06]), REL (HR, 1.03; 99% CI, 0.9-1.1 [P = 0.6]), PFS (HR, 1.06; 99% CI, 1-1.2 [P = 0.2]), and OS (HR, 1.2; 99% CI, 1-1.4 [P = .02]) compared with the reference group (those aged 60-69 years). In patients aged ≥70 years, Mel administered at a dose of 140 mg/m² was found to be associated with worse outcomes compared with Mel administered at a dose of 200 mg/m² , including day 100 NRM (1% [95% CI, 1%-2%] vs 0% [95% CI, 0%-1%]; P = .003]), 2-year PFS (64% [95% CI, 60%-67%] vs 69% [95% CI, 66%-73%]; P = .003), and 2-year OS (85% [95% CI, 82%-87%] vs 89% [95% CI, 86%-91%]; P = .01]), likely representing frailty.

CONCLUSIONS

The results of the current study demonstrated that AHCT remains an effective consolidation therapy among patients with MM across all age groups.

Interim analysis of ZUMA-5: A phase II study of axicabtagene ciloleucel (axi-cel) in patients (pts) with relapsed/refractory indolent non-Hodgkin lymphoma (R/R iNHL)

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Background: Advanced stage iNHL, including follicular lymphoma (FL) and marginal zone lymphoma (MZL), is considered incurable as most pts experience multiple relapses (Wang, et al. Ther Adv Hematol. 2017), highlighting a need for novel therapies. Here, we present interim results from ZUMA-5, a Phase 2, multicenter study of axi-cel, an autologous anti-CD19 chimeric antigen receptor (CAR) T cell therapy, in pts with R/R iNHL. Methods: Adults with R/R FL (Grades 1-3a) or MZL (nodal or extranodal) after ≥ 2 lines of therapy (including an anti-CD20 monoclonal antibody [mAb] with an alkylating agent), and an ECOG of 0 – 1 were eligible. Pts were leukapheresed and received conditioning chemotherapy followed by axi-cel infusion at 2 × 106 CAR T cells/kg. The primary endpoint was objective response rate (ORR) by central review (Cheson, et al. J Clin Oncol. 2014). Secondary endpoints included duration of response (DOR), progression-free survival (PFS), overall survival (OS), safety, and blood levels of cytokines and CAR T cells. Results: As of 8/20/19, 94 pts (80 FL; 14 MZL) received axi-cel with a median follow-up of 11.5 mo (range, 4.2 – 24.9). Median age was 63 y (range, 34 – 79), 47% of pts were male, 52% had stage IV disease, 51% had ≥ 3 FLIPI, and 59% had high tumor bulk (GELF). Pts had a median 3 prior lines of therapy, 66% progressed < 2 y after initial anti-CD20 mAb-containing therapy (POD24), and 73% were refractory to the last prior treatment. Of 87 pts evaluable for efficacy, ORR was 94% (79% complete response [CR] rate). Pts with FL (n = 80) had an ORR of 95% (80% CR rate). Pts with MZL (n = 7) had an ORR of 86% (71% CR rate). Overall, 68% of pts had ongoing responses as of the data cutoff. Updated data, including DOR, PFS, and OS with longer follow-up, will be included in the presentation. Of 94 pts evaluable for safety, 83% experienced Grade ≥ 3 adverse events (AEs), most commonly neutropenia (33%) and anemia (28%). Grade ≥ 3 cytokine release syndrome (CRS; per Lee et al, Blood 2014) and neurologic events (NEs; per CTCAE v4.03) occurred in 11% and 19% of pts, respectively. Median times to onset of CRS and NEs were 4 and 7 d, with median durations of 6 and 14.5 d. There were 2 Grade 5 AEs: multisystem organ failure in the context of CRS (related to axi-cel) and aortic dissection (unrelated to axi-cel). Median peak and AUC0-28 CAR T cell levels were 44 cells/µL and 490 cells/µL × d, respectively. Conclusions: Axi-cel demonstrated significant and durable clinical benefit, with high rates of ORR and CR, and a manageable safety profile in pts with R/R iNHL. Clinical trial information: NCT03105336 .

Lower Graft-versus-Host Disease and Relapse Risk in Post-Transplant Cyclophosphamide-Based Haploidentical versus Matched Sibling Donor Reduced-Intensity Conditioning Transplant for Hodgkin Lymphoma

Classic Hodgkin lymphoma (cHL) patients with relapsed or refractory disease may benefit from allogeneic hematopoietic cell transplantation (allo-HCT), but many lack a matched sibling donor (MSD). Herein, we compare outcomes of 2 reduced-intensity conditioning (RIC) HCT platforms in cHL: T cell-replete related donor haploidentical (haplo) HCT with a post-transplant cyclophosphamide (PTCy)-based approach versus an MSD/calcineurin inhibitor (CNI)-based approach. The study included 596 adult patients who underwent a first RIC allo-HCT for cHL between 2008 and 2016 using either a haplo-PTCy (n = 139) or MSD/CNI-based (n = 457) approach. Overall survival (OS) was the primary endpoint. Secondary endpoints included acute graft-versus-host disease (aGVHD) and chronic GVHD (cGVHD), nonrelapse mortality (NRM), relapse/progression, and progression-free survival (PFS). On multivariate analysis, there was no significant difference between haplo/PTCy and MDS/CNI-based approaches in terms of OS (hazard ratio [HR], 1.07; 95% confidence interval [CI], .79 to 1.45; P = .66) or PFS (HR, .86; 95% CI, .68 to 1.10; P = .22). Haplo/PTCy was associated with a significantly higher risk of grades II to IV aGVHD (odds ratio [OR], 1.73, 95% CI, 1.16 to 2.59; P = .007), but the risk of grades III to IV aGVHD was not significantly different between the 2 cohorts (OR, .61; 95% CI, .29 to 1.27; P = .19). The haplo/PTCy platform provided a significant reduction in cGVHD risk (HR, .45; 95% CI, .32 to .64; P < .001), and a significant reduction in relapse risk (HR, .74; 95% CI, .56 to .97; P = .03). There was a statistically nonsignificant trend toward higher NRM with a haplo/PTCy approach (HR, 1.65; 95% CI, .99 to 2.77; P = .06). Haplo/PTCy-based approaches are associated with lower incidences of cGVHD and relapse, with PFS and OS outcomes comparable with MSD/CNI-based approaches. There was a leaning toward higher NRM with a haplo/PTCy-based platform. These data show that haplo/PTCy allo-HCT in cHL results in survival comparable with MSD/CNI-based allo-HCT.

6-thioguanine: a drug with unrealized potential for cancer therapy

Sixty years ago, 6-thioguanine (6-TG) was introduced into the clinic. We suggest its full potential in therapy may not have been reached. In this paper, we contrast 6-TG and the more widely used 6-mercaptopurine; discuss 6-TG metabolism, pharmacokinetics, dosage and schedule; and summarize many of the early studies that have shown infrequent but nevertheless positive results with 6-TG treatment of cancers. We also consider studies that suggest that combinations of 6-TG with other agents may enhance antitumor effects. Although not yet tested in man, 6-TG has recently been proposed to treat a wide variety of cancers with a high frequency of homozygous deletion of the gene for methylthioadenosine phosphorylase (MTAP), often codeleted with the adjacent tumor suppressor CDKN2A (p16). Among the cancers with a high frequency of MTAP deficiency are leukemias, lymphomas, mesothelioma, melanoma, biliary tract cancer, glioblastoma, osteosarcoma, soft tissue sarcoma, neuroendocrine tumors, and lung, pancreatic, and squamous cell carcinomas. The method involves pretreatment with the naturally occurring nucleoside methylthioadenosine (MTA), the substrate for the enzyme MTAP. MTA pretreatment protects normal host tissues, but not MTAP-deficient cancers, from 6-TG toxicity and permits administration of doses of 6-TG that are much higher than can now be safely administered. The combination of MTA/6-TG has produced substantial shrinkage or slowing of growth in two different xenograft human tumor models: lymphoblastic leukemia and metastatic prostate carcinoma with neuroendocrine features. Further development and a clinical trial of the proposed MTA/6-TG treatment of MTAP-deficient cancers seem warranted.