Peripheral Blood Stem Cells versus Bone Marrow for T Cell-Replete Haploidentical Transplantation with Post-Transplant Cyclophosphamide in Hodgkin Lymphoma

Haploidentical hematopoietic cell transplantation as a platform for natural killer cell immunotherapy

An innovative approach is crucially needed to manage relapse after allogeneic hematopoietic cell transplantation (HCT) in patients with advanced hematological malignancies. This review explores key aspects of haploidentical HCT with post-transplant cyclophosphamide, highlighting the potential and suitability of this platform for natural killer (NK) cell immunotherapy. NK cells, known for their unique abilities to eliminate cancer cells, can also exhibit memory-like features and enhanced cytotoxicity when activated by cytokines. By discussing promising results from clinical trials, the review delves into the recent major advances: donor-derived NK cells can be expanded ex vivo in large numbers, cytokine activation may enhance NK cell persistence and efficacy in vivo, and post-HCT NK cell infusion can improve outcomes in high-risk and/or relapsed myeloid malignancies without increasing the risk of graft-versus-host disease, severe cytokine release syndrome, or neurotoxicity. Looking ahead, cytokine-activated NK cells can be synergized with immunomodulatory agents and/or genetically engineered to enhance their tumor-targeting specificity, cytotoxicity, and persistence while preventing exhaustion. The ongoing exploration of these strategies holds promising preliminary results and could be rapidly translated into clinical applications for the benefit of the patients.

Peripheral blood stem cell versus bone marrow graft for patients ≥60 years undergoing reduced intensity conditioning haploidentical transplantation for acute myeloid leukemia in complete remission: An analysis of the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

In the context of T-cell replete haploidentical stem cell transplantation (Haplo-SCT) using post-transplantation cyclophosphamide (PT-Cy), it is still unknown whether peripheral blood (PB) or bone marrow (BM) is the best graft source. While PB is associated with a higher incidence of graft-versus-host disease (GVHD), it may induce a stronger graft-versus-leukemia effect compared to BM, notably in acute myeloid leukemia (AML). From the EBMT registry database, we compared T-cell replete PB (n = 595) versus BM (n = 209) grafts in a large cohort of 804 patients over the age of 60 years who underwent Haplo-SCT with PT-Cy for an AML in first or second complete remission. The risk of acute GVHD was significantly higher in the PB group (Grade II-IV: HR = 1.67, 95% CI [1.10-2.54], p = 0.01; Grade III-IV: HR = 2.29, 95% CI [1.16-4.54], p = 0.02). No significant difference was observed in chronic GVHD or non-relapse mortality. In the PB group, the risk of relapse was significantly lower in the PB group (HR = 0.65, 95% CI [0.45-0.94], p = 0.02) and leukemia-free survival was significantly better (HR = 0.76, 95% CI [0.59-0.99], p = 0.04), with a trend toward better overall survival (HR = 0.78, 95% CI [0.60-1.01], p = 0.06). We conclude that in the specific context of Haplo-SCT with PT-Cy, PB grafts represent a valid option to decrease the risk of relapse and improve outcome of older AML patients who usually do not benefit from conditioning intensification.

Graft-versus-tumor effect of post-transplant cyclophosphamide-based allogeneic hematopoietic cell transplantation

Post-transplant cyclophosphamide (PTCy) is becoming the standard prophylaxis for graft-versus-host disease (GVHD) in HLA-haploidentical allogeneic hematopoietic cell transplantation (allo-HCT) and in HLA-matched allo-HCT. Immune reconstitution in the post-transplant setting may influence the graft-versus-tumor (GVT) effect because PTCy has a profound effect on T cell and natural killer cell functions and their reconstitution after allo-HCT. However, many recent studies have shown that the incidence of relapse after allo-HCT with PTCy is comparable to that after conventional allo-HCT. To further improve the outcomes, it is critical to establish a strategy to maintain or effectively induce the GVT effect when using PTCy as a platform for GVHD prophylaxis. However, there is a paucity of studies focusing on the GVT effect in allo-HCT with PTCy. Therefore, focusing on this issue may lead to the establishment of more appropriate strategies to improve transplantation outcomes without exacerbating GVHD, including novel therapies involving cell modification.

Combining post-transplant cyclophosphamide with antithymocyte globulin for graft-versus-host disease prophylaxis in hematological malignancies

In search of an ideal partner or alternative to conventional immunosuppressive agents, rabbit anti-thymocyte globulin (ATG) and, more recently, post-transplant cyclophosphamide (PT-Cy) have both emerged as valid and efficient options for preventing graft-versus-host disease (GvHD). To further reduce the risk of GvHD, strategies combining ATG and PT-Cy have recently been investigated. In a haploidentical setting, retrospective studies suggest that combining PT-Cy and ATG may result in a lower incidence of chronic GvHD without increasing the risks of infection or relapse, when compared to PT-Cy without ATG. In haploidentical or unrelated donor settings, adding reduced doses of PT-Cy to ATG may reduce the risk of acute and chronic GvHD and improve survival, particularly GvHD-free, relapse-free survival (GRFS), when compared to ATG without PT-Cy. Overall, the combination of PT-Cy and ATG is a safe and promising approach for patients with hematological malignancies undergoing allogeneic hematopoietic stem cell transplantation (HSCT).

Reduced post-transplant cyclophosphamide dose with antithymocyte globulin in peripheral blood stem cell haploidentical transplantation

Post-transplant cyclophosphamide (PT-Cy) is effective for graft-versus-host disease (GVHD) prophylaxis, but it may cause dose-dependent toxicities, particularly in frail patients. Therefore, we compared the outcomes with a reduced PT-Cy total dose (70 mg/kg) to those with the standard PT-Cy dose (100 mg/kg) in haploidentical hematopoietic cell transplantation (HCT) patients aged ≥ 65 years and those with cardiac comorbidities. All consecutive patients with a hematological malignancy receiving peripheral blood stem cells (PBSCs) after a thiotepa-based conditioning with low-dose antithymocyte globulin were included. Thirty-three patients received PT-Cy at 70 mg/kg and 25 at 100 mg/kg. PT-Cy dose reduction did not increase the risk of GVHD and was associated with faster neutrophil and platelet recovery, and lower cumulative incidences of bacteremia (38% versus 72%, p = 0.004) and cardiac complications (12% versus 44%, p = 0.028). At 2 years, GVHD-free, relapse-free survival (GRFS) was higher with the reduced dose compared to the standard dose (60% versus 33%, p = 0.04). In conclusion, reducing PT-Cy total dose to 70 mg/kg is a safe and valid approach for elderly patients and those with cardiac comorbidities underdoing haploidentical HCT with PBSCs and low-dose antithymocyte globulin. The reduced PT-Cy dose was associated with improved hematological count recovery, lower incidence of toxicities, and higher GRFS.

Umbilical cord blood: an undervalued and underutilized resource in allogeneic hematopoietic stem cell transplant and novel cell therapy applications

PURPOSE OF REVIEW

The purpose of this review is to primarily discuss the unwarranted decline in the use of umbilical cord blood (UCB) as a source of donor hematopoietic stem cells (HSC) for hematopoietic cell transplantation (HCT) and the resulting important implications in addressing healthcare inequities, and secondly to highlight the incredible potential of UCB and related birthing tissues for the development of a broad range of therapies to treat human disease including but not limited to oncology, neurologic, cardiac, orthopedic and immunologic conditions.

RECENT FINDINGS

When current best practices are followed, unrelated donor umbilical cord blood transplant (CBT) can provide superior quality of life-related survival compared to other allogeneic HSC donor sources (sibling, matched or mismatched unrelated, and haploidentical) through decreased risks of relapse and chronic graft vs. host disease. Current best practices include improved UCB donor selection criteria with consideration of higher resolution human leukocyte antigen (HLA) typing and CD34+ cell dose, availability of newer myeloablative but reduced toxicity conditioning regimens, and rigorous supportive care in the early posttransplant period with monitoring for known complications, especially related to viral and other infections that may require intervention. Emerging best practice may include the use of ex vivo expanded single-unit CBT rather than double-unit CBT (dCBT) or 'haplo-cord' transplant, and the incorporation of posttransplant cyclophosphamide as with haploidentical transplant and/or incorporation of novel posttransplant therapies to reduce the risk of relapse, such as NK cell adoptive transfer. Novel, non-HCT uses of UCB and birthing tissue include the production of UCB-derived immune effector cell therapies such as unmodified NK cells, chimeric antigen receptor-natural killer cells and immune T-cell populations, the isolation of mesenchymal stem cells for immune modulatory treatments and derivation of induced pluripotent stem cells haplobanks for regenerative medicine development and population studies to facilitate exploration of drug development through functional genomics.

SUMMARY

The potential of allogeneic UCB for HCT and novel cell-based therapies is undervalued and underutilized. The inventory of high-quality UCB units available from public cord blood banks (CBB) should be expanding rather than contracting in order to address ongoing healthcare inequities and to maintain a valuable source of cellular starting material for cell and gene therapies and regenerative medicine approaches. The expertise in Good Manufacturing Practice-grade manufacturing provided by CBB should be supported to effectively partner with groups developing UCB for novel cell-based therapies.

Haploidentical peripheral blood stem cell transplantation combined with unrelated cord blood in hematologic malignancy patients: A report of 80 cases

The outcomes of 80 patients with hematologic malignancies who received haploidentical peripheral blood stem cell transplantation (haplo-PBSCT) combined with unrelated cord blood (UCB) from March 2017 to June 2020 were analyzed in this retrospective study. Anti-thymocyte globulin(ATG) was administered at a dose of 7.5 mg/kg. The median time for neutrophil and platelet engraftment was 13(range: 8-22) days and 14(range: 8-103) days, respectively. The 30-day cumulative incidence of neutrophil engraftment was 100%, and the 100-day cumulative incidence of platelet engraftment was 95%. All patients achieved complete haploidentical peripheral blood stem cell engraftment, and no cord blood chimerism was observed. The cumulative incidence of grades II-IV and grades III-IV acute graft-versus-host disease (aGVHD) on 100-day was 26.3%(95%CI: 17.2%–36.3%) and 5.0%(95%CI: 1.6%–11.4%), respectively. The estimated cumulative incidence of chronic GVHD (cGVHD) and moderate-severe cGVHD at 3-year was 43.3%(95%CI: 31.6%–54.4%) and 16.0%(95%CI: 8.7%–25.2%), respectively. The estimated 3-year cumulative incidence of relapse and non-relapse mortality was 18.8%(95%CI: 10.0%–29.7%) and 17.8%(95%CI: 9.9%–27.5%), respectively. The estimated 3-year probabilities of overall survival, disease-free survival, GVHD/relapse-free survival were 77.6%(95%CI: 68.3%–88.1%), 63.4%(95%CI: 52.6%–76.5%), and 55.5%(95%CI: 44.8%–68.7%), respectively. These satisfying results suggested that haplo-PBSCT combined with UCB is an alternative transplantation protocol for hematologic malignancies.

Stem-Cell Transplantation in Adult Patients with Relapsed/Refractory Hodgkin Lymphoma

Although the majority of patients with Hodgkin lymphoma (HL) are cured with initial therapy, in 85–90% of early stage and 70–80% of advanced-stage disease cases, relapse remains a major problem. Autologous stem-cell transplantation (auto-HCT) after salvage chemotherapy is currently considered to be the standard of care for patients who relapse after first-line chemotherapy or for whom first-line treatment fails. The curative capacity of auto-HCT has been improving with the introduction of new drug-based salvage strategies and consolidation strategies after auto-HCT. Allogeneic stem-cell transplantation (allo-HCT) represents a reasonable treatment option for young patients who relapse or progress after auto-HCT and have chemosensitive disease at the time of transplantation. Allo-HCT is a valid treatment strategy for patients with relapse/refractory HL (r/r HL) because the results have improved over time, mainly with the safe combination of allo-HCT and new drugs. Bearing in mind that outcomes after haploidentical stem-cell transplantation (haplo-HCT) are comparable with those for matched sibling donors and matched unrelated donors, haplo-HCT is now the preferred alternative donor source for patients with r/r HL without a donor or when there is urgency to find a donor if a matched related donor is not present. The development of new drugs such as anti-CD 30 monoclonal antibodies and checkpoint inhibitors (CPI) for relapsed or refractory HL has demonstrated high response rates and durable remissions, and challenged the role and timing of HCT. The treatment of patients with HL who develop disease recurrence or progression after allo-HCT remains a real challenge and an unmet need.

Is Post-Transplant Cyclophosphamide the New Methotrexate?

Introducing post-transplant, cyclophosphamide (PT-Cy) graft-versus-host disease (GVHD) prophylaxis in the setting of haploidentical donor transplantation has marked the most important advance in allogeneic hematopoietic cell transplantation (alloHCT) within the past 15 years. The efficacy of this procedure and its simple features have allowed for the significantly widespread application of alloHCT worldwide. Indeed, the procedure's effectiveness in reducing immunological complications in the haploidentical setting has even challenged the status quo use of calcineurin-inhibitor, methotrexate-based GVHD prophylaxis in the setting of HLA-identical donors. Currently, however, prospective clinical trials in support of PT-Cy-based GVHD prophylaxis in the HLA-matched setting are striving to resolve the matter of its potential role. This review will briefly report the overall outcomes of PT-Cy-based GVHD prophylaxis in the haploidentical setting and summarize results obtained in the HLA-identical field. We will present future perspectives at the end of the manuscript.

Outcomes after Haploidentical Hematopoietic Cell Transplantation with Post-Transplantation Cyclophosphamide: A Systematic Review and Meta-Analysis Comparing Myeloablative with Reduced-Intensity Conditioning Regimens and Bone Marrow with Peripheral Blood Stem Cell Grafts

Haploidentical hematopoietic cell transplantation (haplo-HCT) with post-transplantation cyclophosphamide (PTCy) may be the sole available curative option for several hematologic malignancies. However, the best choice of conditioning regimen and graft source has not been established. This study was conducted to compare myeloablative conditioning (MAC) regimens with reduced-intensity conditioning (RIC) regimens and peripheral blood stem cell (PBSC) grafts with bone marrow (BM) grafts in the haplo-HCT setting with PTCy. We performed a systematic review and meta-analysis of studies comparing MAC with RIC and PBSC with BM in the haplo-HCT. The search was conducted in PubMed and TRIALS on February 2, 2021, without a date limit. We excluded studies with >30% non-PTCy graft-versus-host disease (GVHD) prophylaxis and >30% nonmalignant diseases. We screened 570 abstracts from PubMed and TRIALS and selected 20 for full-text review and 17 for inclusion in the qualitative and quantitative analyses. For PBSC versus BM grafts, we found no difference in overall survival (OS; hazard ratio [HR], 1.05; P = .61; nPBSC = 1983; nBM = 2124), progression-free survival (PFS; HR, 0.95; P = .52; nPBSC = 2663, nBM = 2769), graft-versus-host disease (GVHD)-free relapse-free survival (GRFS; HR, 1.16; P = .07; nPBSC = 1454; pBM = 1647), or nonrelapse mortality (HR, 1.14; P = .13; nPBSC = 1664; nBM = 1862). Relapse was lower with the use of PBSC grafts (HR, 0.84; P = .001; nPBSC = 2663; nBM = 2769). The rates of acute GVHD (aGVHD) and chronic GVHD (cGVHD) were higher with PBSC grafts (aGVHD grade II-IV: HR, 1.67; P < .001; nPBSC = 2663; nBM = 2802; aGVHD grade III-IV: HR, 1.82; P < .001; nPBSC = 1826; nBM = 2000; cGVHD: HR, 1.46; P = .002; nPBSC = 2686; nBM = 2815). Engraftment was higher with PBSC grafts (HR, 1.27; P < .001; nPBSC = 1461; nBM = 1717). Comparing MAC and RIC, the use of MAC was associated with less relapse (HR, 0.70; P < .001; nMAC = 1929; nRIC = 2662), higher nonrelapse mortality (HR, 1.24; P = .002; nMAC = 2016; nRIC = 2790), but better PFS (HR, 0.86; P = .002; nMAC = 1929; nRIC = 2662). There were no differences between the 2 conditioning regimens in OS (HR, .95; P = .32; nMAC = 2123; nRIC = 3155), GRFS (HR, 0.97; P = .67; nMAC = 1182; nRIC = 1330), grade II-IV aGVHD (HR, 1.01; P = .81; nMAC = 2099; nRIC = 3090), or cGVHD (HR, 1.05; P = .44; nMAC=1929; nRIC = 2662). This analysis shows that the use of BM grafts is associated with comparable outcomes as seen with PBSC grafts despite a lower incidence of GVHD and a higher relapse rate. The use of MAC regimens is associated with improved PFS. These results suggest that for fit patients, MAC remains the optimal conditioning regimen in terms of mortality, and that the use of PBSC grafts may further decrease relapse risk and hasten engraftment, provided that further strategies can be incorporated to decrease GVHD. Prospective comparisons are awaited.

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.

G-CSF-Primed Peripheral Blood Stem Cell Haploidentical Transplantation Could Achieve Satisfactory Clinical Outcomes for Acute Leukemia Patients in the First Complete Remission: A Registered Study

G-CSF-mobilized peripheral blood (G-PB) harvest is the predominant graft for identical sibling donor and unrelated donor allogeneic hematopoietic stem cell transplantation (HSCT) recipients, but it was controversial in haploidentical related donor (HID) HSCT. In this registry study, we aimed to identify the efficacy of HID G-PB HSCT (HID-PBSCT) for acute leukemia (AL) patients in first complete remission (CR1). Also, we reported the outcomes for the use of G-PB grafts in comparison with the combination of G-BM and G-PB grafts in HID HSCT recipients. Sixty-seven AL patients in CR1 who received HID-PBSCT were recruited at Institute of Hematology, Peking University. Patients who received haploidentical HSCT using the combination of G-BM and G-PB harvests in the same period were enrolled as controls (n=392). The median time from HSCT to neutrophil and platelet engraftment was 12 days (range, 9-19 days) and 12 days (range, 8-171 days), respectively. The 28-day cumulative incidence of neutrophil and platelet engraftment after HSCT was 98.5% and 95.5%, respectively. The cumulative incidences of grade II-IV and grade III-IV acute graft-versus-host disease (GVHD) were 29.9% (95%CI 18.8-40.9%) and 7.5% (95%CI 1.1-13.8%), respectively. The cumulative incidences of total and moderate-severe chronic GVHD were 54.9% (95%CI 40.9-68.8%) and 17.4% (95%CI 6.7-28.0%), respectively. The cumulative incidences of relapse and non-relapse mortality were 13.9% (95%CI 5.4-22.5%) and 3.4% (95%CI 0-8.1%), respectively. The probabilities of overall survival (OS) and leukemia-free survival (LFS) were 84.7% (95%CI 74.7-94.7%) and 82.7% (95%CI 73.3-92.1%) respectively. Compared with the HID HSCT recipients using the combination of G-BM and G-PB grafts, the engraftments of neutrophil and platelet were both significantly faster for the G-PB group, and the other clinical outcomes were all comparable between the groups. In multivariate analysis, graft types did not influence the clinical outcomes. Overall, for the patients with AL CR1, G-PB graft could be considered an acceptable graft for HID HSCT recipients. This study was registered at https://clinicaltrials.gov as NCT03756675.

Haploidentical Stem Cell Transplantation in Lymphomas-Expectations and Pitfalls

T-cell replete Haploidentical stem cell transplantation (Haplo-SCT) with Post-transplant cyclophosphamide (PT-Cy) is an emerging therapeutic option for patients with advanced relapsed or refractory lymphoma. The feasibility of this platform is supported by several retrospective studies showing a toxicity profile that is improved relative to umbilical cord blood and mismatched unrelated donor (UD) transplant and comparable to matched unrelated donor transplant. In particular, cumulative incidence of chronic graft-versus-host disease (GVHD) is reduced after Haplo-SCT relative to UD and matched related donor (MRD) transplant thanks to PT-Cy employed as GVHD prophylaxis. This achievement, together with a similar incidence of acute GVHD and disease relapse, results in a promising advantage of Haplo-SCT in terms of relapse-free/GVHD free survival. Unmet needs of the Haplo-SCT platform are represented by the persistence of a not negligible rate of non-relapse mortality, especially due to infections and disease relapse. Future efforts are warranted in order to reduce life-threatening infections and to employ Halo-SCT with PT-Cy as a platform to build new immunotherapeutic strategies.

Salvage Therapy for Hodgkin's Lymphoma: A Review of Current Regimens and Outcomes

Relapse/refractory Hodgkin lymphoma patients are still a clinical concern. Indeed, despite more effective first-line chemotherapy regimens and better stratification of unresponsive patients by clinical factors and use of early PET, roughly one-third of such patients need salvage chemotherapy and consolidation with high-dose chemotherapy. In this paper, the authors review the different salvage treatments, with special emphasis on newer combinations with brentuximab vedotin or check point inhibitors. The overall response rate is constantly increasing, with a complete remission rate approaching 80%. Functional response evaluation by PET imaging is a strong predictive factor of longer survival, and more sophisticated tools, such as detection of circulating tumour DNA, are emerging to refine the disease-status assessment after treatment. Consolidation by high-dose chemotherapy is still considered the standard of care in chemosensitive patients, leading to a high fraction of patients towards long-term disease control. Maintenance therapy with BV is now approved, reducing disease relapse/progression. An increasing number of Hodgkin lymphoma patients will be cured after first- and second-line therapy, and long-term toxicity needs to be continuously assessed and avoided.

Nonmyeloablative Conditioning Regimen before T Cell Replete Haploidentical Transplantation with Post-Transplant Cyclophosphamide for Advanced Hodgkin and Non-Hodgkin Lymphomas

Allogeneic hematopoietic stem cell transplantation (allo-SCT) is a valid option in patients with refractory lymphomas. HLA haploidentical stem cell transplantation (haplo-SCT) expanded the accessibility to allogeneic hematopoietic cell transplantation. The aims of study were to retrospectively assess the toxicity and efficacy of haplo-SCT using nonmyeloablative conditioning in patients with advanced lymphoma. In total, 147 patients with advanced lymphoma at 2 partner institutions were included. Patients received a uniform nonmyeloablative conditioning regimen and graft-versus-host disease (GVHD) prophylaxis. The primary endpoints were progression-free survival (PFS), overall survival (OS), GVHD, nonrelapse mortality, and GVHD, relapse-free survival (GRFS). Median follow-up was 39 months (range, 6 to 114 months). The median age was 46 years (range, 19 to 71 years). Sixty-five percent of patients were in complete remission (CR) at transplantation. Cumulative incidence of grade II to IV acute GVHD was 30% (95% confidence interval [Cl], 23% to 38%). Two-year cumulative incidence of all grades of chronic GVHD was 13% (95% CI, 8% to 20%). Two-year cumulative incidence of disease relapse was 19% (95% CI, 14% to 27%), with a higher incidence in patients not being in CR at allo-HCT (CR versus not CR: 12% versus 33%, P = .006). Two-year PFS, OS, and GRFS were 66% (95% CI, 59-75), 73% (95% CI, 66-81), and 56% (95% CI, 48-65), respectively. Haplo-SCT with post-transplantation cyclophosphamide may be considered a valid option for patients with aggressive lymphoma and deserves further evaluation.

Safety and efficacy of anti-programmed cell death-1 monoclonal antibodies before and after allogeneic hematopoietic cell transplantation for relapsed or refractory Hodgkin lymphoma: a multicenter retrospective study

We conducted a multicenter study on anti-programmed cell death-1 monoclonal antibodies (anti-PD-1 mAbs) before/after allogeneic hematopoietic cell transplantation (allo-HCT) for Hodgkin lymphoma. Anti-PD-1 mAbs were administered to 25 patients before allo-HCT and to 20 after allo-HCT. In pre-allo-HCT setting, the median interval from the last administration to allo-HCT was 59 days. After allo-HCT, 12 patients developed non-infectious febrile syndrome requiring high-dose corticosteroid. The cumulative incidences of grade II-IV acute graft-versus-host disease (aGvHD) were 47.1%. Eight patients who had GvHD prophylaxis with post-transplant cyclophosphamide (PTCy) had less frequent aGvHD (grade II-IV, 14.6% versus 58.8%; P = 0.086). The 1 year overall survival (OS), relapse/progression, and non-relapse mortality rates were 81.3%, 27.9%, and 8.4%. In post-allo-HCT setting, the median interval from allo-HCT to the first administration was 589 days. The overall and complete response rates were 75% and 40%. At 100 days after anti-PD-1 therapy, the cumulative incidences of grade II-IV aGvHD, moderate-to-severe chronic GvHD, and grade 3-4 immune-related toxicity were 15.0%, 30.0%, and 30.0%. While the 1 year relapse/progression rate was 47.4%, the 1 year OS probability was 89.7%. In conclusion, immune-related complications were frequent despite modifications of GvHD prophylaxis or anti-PD-1 mAb dosing. In anti-PD-1-mAb-pretreated patients, PTCy-based GvHD prophylaxis may be effective.