Allogeneic transplantation after PD-1 blockade for classic Hodgkin lymphoma

Real world effectiveness and safety of nivolumab in patients with relapsed or refractory classical hodgkin lymphoma

OBJECTIVE

The primary objective is to describe the real-life effectiveness and safety of nivolumab treatment in patients with relapsed or refractory classical Hodgkin's lymphoma. The secondary objective is to describe the therapeutic management after nivolumab monotherapy.

METHOD

Observational, retrospective, multidisciplinary study including all patients with relapsed or refractory classical Hodgkin's lymphoma treated with nivolumab monotherapy from November 2015 to March 2023. Patient and treatment-related variables were collected. Effectiveness was measured as overall response rate, progression-free survival and overall survival. Safety was measured as percentage of patients with adverse effects and severity.

RESULTS

Thirteen patients were included, median age 37.5 years (RIQ: 25.3-54.7), 84.6% male. The median number of previous lines of therapy was 3 (RIQ: 2.0-4.5), including autologous hematopoietic stem cell transplantation (84.6%) and brentuximab vedotin (100%). All received nivolumab 3 mg/kg/14 days, with a median of 11 cycles (RIQ: 6.5-20.5) per patient. Median time on treatment was 4.9 months (RIQ: 3.0-9.6) and median follow-up time was 9.2 months (RIQ: 5.6-32.3). Complete response was achieved by 3 patients (23.1%), partial response by 3 (23.1%), stable disease by 3 (23.1%) and progression by 4 (30.8%). The objective response rate was 46.2%. Median progression-free survival was 23.9 months (95%CI: 0-49.1), median overall survival was not reached. At the study cutoff date, five patients had died (38.5%), four were in complete remission without active treatment (30.8%) and four were continuing treatment (30.8%). Adverse events occurred in 76.9% of patients, 44% of severity ≥3, the most frequent being hypothyroidism and hepatotoxicity. One patient discontinued treatment due to pneumonitis, two suffered treatment delays (thrombocytopenia and hypertransaminemia) and one changed the regimen to monthly (pulmonary toxicity).

CONCLUSIONS

Nivolumab in the treatment of relapsed or refractory classical Hodgkin's lymphoma has confirmed in the study sample favorable effectiveness data, expressed as objective response rate of 46.2% and clinical benefit of 69.2%. Safety was acceptable, manageable, and consistent with that described in the literature.

Outcome of High-Dose Chemotherapy Followed by Autologous Stem Cell Transplantation in Relapsed/Refractory Hodgkin Lymphoma after Different Numbers of Salvage Regimens

The introduction of novel drugs (PD-1 inhibitors and/or brentuximab vedotin) into salvage regimens has improved the response rate and the outcome of patients with relapsed/refractory Hodgkin lymphoma. However, the impact of new drugs on the outcome has not been adequately investigated so far. We retrospectively analyzed 42 consecutive patients treated at our institution with high-dose chemotherapy/autologous stem cell transplantation after either one standard chemotherapy represented by BEGEV (n = 28) or >1 salvage therapy (ST) comprising novel drugs (n = 14). With a median follow-up of 24 months, the 2-year cumulative incidence of relapse was similar between the two cohorts: 26% for 1 ST and 18% for >1 ST (p = 0.822). Consistently, overall survival and progression-free survival did not differ among the two groups: 3-year overall survival was 91% and 89% (p = 0.731), respectively, and 3-year progression-free survival was 74% and 83% (p = 0.822) for only one and more than one salvage regimens, respectively. Of note, the post-transplant side effects and engraftment rates were similar between the 1 ST and >1 ST cohorts. In conclusion, consolidation with high-dose chemotherapy/autologous stem cell transplantation is a safe and curative option, even for patients achieving disease response after more than one rescue line of therapy.

Overall survival of patients with cHL who progress after autologous stem cell transplant: results in the novel agent era

In the pre-novel agent era, the median postprogression overall survival (PPS) of patients with classic Hodgkin lymphoma (cHL) who progress after autologous stem cell transplant (ASCT) was 2 to 3 years. Recently, checkpoint inhibitors (CPI) and brentuximab vedotin (BV) have improved the depth and durability of response in this population. Here, we report the estimate of PPS in patients with relapsed cHL after ASCT in the era of CPI and BV. In this multicenter retrospective study of 15 participating institutions, adult patients with relapsed cHL after ASCT were included. Study objective was postprogression overall survival (PPS), defined as the time from posttransplant progression to death or last follow-up. Of 1158 patients who underwent ASCT, 367 had progressive disease. Median age was 34 years (range, 27-46) and 192 were male. Median PPS was 114.57 months (95% confidence interval [CI], 91-not achieved) or 9.5 years. In multivariate analysis, increasing age, progression within 6 months, and pre-ASCT positive positron emission tomography scan were associated with inferior PPS. When adjusted for these features, patients who received CPI, but not BV, as first treatment for post-ASCT progression had significantly higher PPS than the no CPI/no BV group (hazard ratio, 3.5; 95% CI, 1.6-7.8; P = .001). Receipt of allogeneic SCT (Allo-SCT) did not improve PPS. In the era of novel agents, progressive cHL after ASCT had long survival that compares favorably with previous reports. Patients who receive CPI as first treatment for progression had higher PPS. Receipt to Allo-SCT was not associated with PPS in this population.

Genetic and pharmaceutical targeting of HIF1α allows combo-immunotherapy to boost graft vs. leukemia without exacerbation graft vs. host disease

Despite potential impact on the graft vs. leukemia (GVL) effect, immunotherapy targeting CTLA-4 and/or PD-1 has not been successfully combined with bone marrow transplant (BMT) because it exacerbates graft vs. host disease (GVHD). Here, using models of GVHD and leukemia, we demonstrate that targeting hypoxia-inducible factor 1α (HIF1α) via pharmacological or genetic approaches reduces GVHD by inducing PDL1 expression on host tissue while selectively inhibiting PDL1 in leukemia cells to enhance the GVL effect. More importantly, combination of HIF1α inhibition with anti-CTLA-4 antibodies allows simultaneous inhibition of both PDL1 and CTLA-4 checkpoints to achieve better outcomes in models of mouse and human BMT-leukemia settings. These findings provide an approach to enhance the curative effect of BMT for leukemia and broaden the impact of cancer immunotherapy.

The therapeutic potential of PD-1/PD-L1 pathway on immune-related diseases: Based on the innate and adaptive immune components

Currently, immunotherapy targeting programmed cell death 1 (PD-1) or programmed death ligand 1 (PD-L1) has revolutionized the treatment strategy of human cancer patients. Meanwhile, PD-1/PD-L1 pathway has also been implicated in the pathogenesis of many immune-related diseases, such as autoimmune diseases, chronic infection diseases and adverse pregnancy outcomes, by regulating components of the innate and adaptive immune systems. Given the power of the new therapy, a better understanding of the regulatory effects of PD-1/PD-L1 pathway on innate and adaptive immune responses in immune-related diseases will facilitate the discovery of novel biomarkers and therapeutic drug targets. Targeting this pathway may successfully halt or potentially even reverse these pathological processes. In this review, we discuss recent major advances in PD-1/PD-L1 axis regulating innate and adaptive immune components in immune-related diseases. We reveal that the impact of PD-1/PD-L1 axis on the immune system is complex and manifold and multi-strategies on the targeted PD-1/PD-L1 axis are taken in the treatment of immune-related diseases. Consequently, targeting PD-1/PD-L1 pathway, alone or in combination with other treatments, may represent a novel strategy for future therapeutic intervention on immune-related diseases.

Nivolumab for relapsed/refractory classical Hodgkin lymphoma: 5-year survival from the pivotal phase 2 CheckMate 205 study

Patients with relapsed/refractory (R/R) classical Hodgkin lymphoma (cHL) for whom autologous hematopoietic cell transplantation (auto-HCT) had failed experienced frequent and durable responses to nivolumab in the phase 2 CheckMate 205 trial. We present updated results (median follow-up, ∼5 years). Patients with R/R cHL who were brentuximab vedotin (BV)-naive (cohort A), received BV after auto-HCT (cohort B), or received BV before and/or after auto-HCT (cohort C) were administered with nivolumab 3 mg/kg IV every 2 weeks until progression or unacceptable toxicity. Patients in cohort C with complete remission (CR) for 1 year could discontinue nivolumab and resume upon relapse. Among 243 patients (cohort A, n = 63; B, n = 80; and C, n = 100), the objective response rate (ORR) was 71.2% (95% confidence interval [CI], 65.1-76.8); the CR rate was 21.4% (95% CI, 16.4-27.1). Median duration of response, CR, and partial remission were 18.2 (95% CI, 14.7-26.1), 30.3, and 13.5 months, respectively. Median progression-free survival was 15.1 months (95% CI, 11.3-18.5). Median overall survival (OS) was not reached; OS at 5 years was 71.4% (95% CI, 64.8-77.1). In cohort C, all 3 patients who discontinued in CR and were subsequently re-treated achieved objective response. No new or unexpected safety signals were identified. This 5-year follow-up of CheckMate 205 demonstrated favorable OS and confirmed efficacy and safety of nivolumab in R/R cHL after auto-HCT failure. Results suggest patients may discontinue treatment after persistent CR and reinitiate upon progression. This trial was registered at www.clinicaltrials.gov as #NCT02181713.

Safety and efficacy of immune checkpoint inhibitors after allogeneic hematopoietic cell transplantation

The immune system plays a major role in preventing infections and cancers. Impairment in immunity may facilitate the development of neoplasia owing to defective immune surveillance, among other mechanisms. Immune evasion plays a significant role in relapse after allogeneic hematopoietic cell transplantation (alloHCT); one purported mechanism is through immune checkpoint signaling pathways. Checkpoint inhibitors (CPIs) are FDA approved for relapsed classical Hodgkin's Lymphoma (cHL), primary mediastinal large B cell Lymphoma (PMBCL) and other solid tumors. Retrospective studies evaluating the outcomes of alloHCT after prior exposure to CPIs showed favorable survival outcomes but high rates of graft-versus-host disease (GVHD); the risk appears to be lower when using post-transplant cyclophosphamide as GVHD prophylaxis. CPIs have increasingly been used to prevent or treat post-alloHCT relapse. Available data, albeit limited, supports the clinical activity of CPIs in post-alloHCT relapse; however, serious and even fatal cases of GVHD have been reported. The optimal timing, schedule, dosing, and patients likely to benefit from this strategy are yet to be identified. In this review, we highlight the immune system's role in cancer surveillance and relapse prevention and discuss the current clinical evidence of CPIs use in post-alloHCT relapse.

Optimizing Treatment for Relapsed/Refractory Classic Hodgkin Lymphoma in the Era of Immunotherapy

Most patients with classic Hodgkin lymphoma (cHL) are cured with combination chemotherapy, but approximately 10-20% will relapse, and another 5-10% will have primary refractory disease. The treatment landscape of relapsed/refractory (R/R) cHL has evolved significantly over the past decade following the approval of brentuximab vedotin (BV), an anti-CD30 antibody-drug conjugate, and the PD-1 inhibitors nivolumab and pembrolizumab. These agents have significantly expanded options for salvage therapy prior to autologous hematopoietic cell transplantation (AHCT), post-transplant maintenance, and treatment of relapse after AHCT, which have led to improved survival in the modern era. In this review, we highlight our approach to the management of R/R cHL in 2023 with a focus on choosing first salvage therapy, post-transplant maintenance, and treatment of relapse after AHCT. We also discuss the management of older adults and transplant-ineligible patients, who require a separate approach. Finally, we review novel immunotherapy approaches in clinical trials, including combinations of PD-1 inhibitors with other immune-activating agents as well as novel antibody-drug conjugates, bispecific antibodies, and cellular immunotherapies. Ongoing studies assessing biomarkers of response to immunotherapy and dynamic biomarkers such as circulating tumor DNA may further inform treatment decisions and enable a more personalized approach in the future.

Five-year follow-up of KEYNOTE-087: pembrolizumab monotherapy for relapsed/refractory classical Hodgkin lymphoma

Previous analyses of the phase 2 KEYNOTE-087 (NCT02453594) trial of pembrolizumab monotherapy demonstrated effective antitumor activity with acceptable safety in patients with relapsed or refractory (R/R) classical Hodgkin lymphoma (cHL). However, long-term response durability and outcome of patients who receive a second course after treatment discontinuation after complete response (CR) remain of clinical interest. We present KEYNOTE-087 data after >5 years of median follow-up. Patients with R/R cHL and progressive disease (PD) after autologous stem cell transplantation (ASCT) and brentuximab vedotin (BV; cohort 1), salvage chemotherapy and BV without ASCT (cohort 2), or ASCT without subsequent BV (cohort 3), received pembrolizumab for ≤2 years. Patients in CR who discontinued treatment and subsequently experienced PD were eligible for second-course pembrolizumab. Primary end points were the objective response rate (ORR) using blinded central review and safety. The median follow-up was 63.7 months. ORR was 71.4% (95% confidence interval [CI], 64.8-77.4; CR, 27.6%; partial response, 43.8%). Median duration of response (DOR) was 16.6 months; median progression-free survival was 13.7 months. A quarter of responders, including half of complete responders, maintained a response for ≥4 years. Median overall survival was not achieved. Among 20 patients receiving second-course pembrolizumab, ORR for 19 evaluable patients was 73.7% (95% CI, 48.8-90.8); median DOR was 15.2 months. Any-grade treatment-related adverse events occurred in 72.9% of patients and grade 3 or 4 adverse events occurred in 12.9% of patients; no treatment-related deaths occurred. Single-agent pembrolizumab can induce durable responses, particularly in patients achieving CR. Second-course pembrolizumab frequently reinduced sustained responses after relapse from initial CR.

Sequencing novel agents in the treatment of classical Hodgkin lymphoma

INTRODUCTION

Classical Hodgkin lymphoma (cHL) is a curable disease, with durable remission achieved in about 80% of patients following first-line treatment. Three new drugs were introduced to the daily use in cHL: brentuximab vedotin (BV), nivolumab, and pembrolizumab. All three drugs were initially approved for the treatment of relapsed/refractory cHL (RRHL) and with their promising outcomes, they are now incorporated in different stages of the treatment.

AREAS COVERED

We performed a literature search using PubMed on all cHL studies investigating BV and CPIs within the past 10 years. We analyzed literature to presume the sequencing of these novel agents.

EXPERT OPINION

Addition of BV or nivolumab to AVD backbone in the frontline setting showed promising activity in advanced stage cHL. BV and CPIs combined with chemotherapy in the second-line treatment of cHL are evaluated in phase 2 studies and comparable results are reported. The results of BrECADD, with good efficacy and toxicity profile, should be followed. Pembrolizumab was shown to be more effective in RRHL compared to BV in patients who have relapsed post-ASCT or ineligible for ASCT. BV is used in post-ASCT maintenance in high-risk cases, although its role will be questioned as it is increasingly used in the frontline treatment.

Tackling the dysregulated immune-checkpoints in classical Hodgkin lymphoma: bidirectional regulations between the microenvironment and Hodgkin/Reed-Sternberg cells

Immune evasion is considered one of the modern hallmarks of cancer and is a key element in the pathogenesis of classical Hodgkin Lymphoma (cHL). This haematological cancer achieves effective avoidance of the host's immune system by overexpressing the PD-L1 and PD-L2 proteins on the surface of the neoplastic cells. Subversion of the PD-1/PD-L axis, however, is not the sole contributor to immune evasion in cHL, as the microenvironment nurtured by the Hodgkin/Reed-Sternberg cells is a major player in the creation of a biological niche that sustains their survival and hinders immune recognition. In this review, we will discuss the physiology of the PD-1/PD-L axis and how cHL is able to exploit a plethora of different molecular mechanisms to build an immunosuppressive microenvironment and achieve optimal immune evasion. We will then discuss the success obtained by checkpoint inhibitors (CPI) in treating cHL, both as single agents and as part of combination strategies, analysing the rationale for their combination with traditional chemotherapeutic compounds and the proposed mechanisms of resistance to CPI immunotherapy.

Single-center phase 2 study of PD-1 inhibitor combined with DNA hypomethylation agent + CAG regimen in patients with relapsed/refractory acute myeloid leukemia

Anti-PD-1 monotherapy had limited clinical efficacy in relapsed/refractory (r/r) AML patients with higher PD-1 and PD-L1 expression. Hence, we investigated the efficacy and safety of PD-1 inhibitor with DNA hypomethylating agent (HMA) + CAG regimen in patients who had failed prior AML therapy. In this phase 2, single-arm study, r/r AML patients received azacitidine or decitabine plus CAG regimen with tislelizumab. Primary endpoints were efficacy (objective response rate [ORR]) and safety. Secondary endpoints included overall survival (OS), event-free survival (EFS) and duration of response (DOR). Statistical analyses were performed using Stata 14.0 and SPSS 20.0 software where P < 0.05 denoted significance. Twenty-seven patients were enrolled patients and completed 1 cycle, and 14 (51.9%) and 4 (14.8%) patients completed 2 and 3 cycles, respectively. ORR was 63% (14: complete remission [CR]/CR with incomplete hematologic recovery [CRi], 3: partial remission (PR), 10: no response [NR]). Median OS (mOS) and EFS were 9.7 and 9.2 months, respectively. With a median follow-up of 8.2 months (1.1-26.9), the mOS was not reached in responders (CR/CRi/PR) while it was 2.4 months (0.0-5.4) in nonresponders (P = 0.002). Grade 2-3 immune-related adverse events (irAEs) were observed in 4 (14.8%) patients and 3 nonresponders died of lung infection after treatment. Tislelizumab + HMA + CAG regimen showed improved outcomes in r/r AML patients with lower pretherapy leukemia burden. irAEs were mild and low-grade and higher pretherapy bone marrow CD4⁺ CD127⁺ PD-1⁺ T cells might serve as a predictor of treatment response.ClinicalTrials.gov identifier NCT04541277.

Allogeneic hematopoietic stem cell transplantation for NK/T-cell lymphoma: an international collaborative analysis

Natural killer/T-cell lymphomas (NKTCL) represent rare and aggressive lymphoid malignancies. Patients (pts) with relapsed/refractory disease after Asparaginase (ASPA)-based chemotherapy have a dismal prognosis. To better define the role of allogeneic hematopoietic stem cell transplantation (allo-HSCT), we conducted a retrospective analysis of data shared with the European Society for Blood and Marrow Transplantation (EBMT) and cooperating Asian centers. We identified 135 pts who received allo-HSCT between 2010 and 2020. Median age was 43.4 years at allo-HSCT, 68.1% were male. Ninety-seven pts (71.9 %) were European, 38 pts (28.1%) Asian. High Prognostic Index for NKTCL (PINK) scores were reported for 44.4%; 76.3% had >1 treatment, 20.7% previous auto-HSCT, and 74.1% ASPA-containing regimens prior to allo-HSCT. Most (79.3%) pts were transplanted in CR/PR. With a median follow-up of 4.8 years, 3-year progression-free(PFS) and overall survival were 48.6% (95%-CI:39.5-57%) and 55.6% (95%-CI:46.5-63.8%). Non-relapse mortality at 1 year was 14.8% (95%-CI:9.3-21.5%) and 1-year relapse incidence 29.6% (95%-CI:21.9-37.6%). In multivariate analyses, shorter time interval (0-12 months) between diagnosis and allo-HSCT [HR = 2.12 (95%-CI:1.03-4.34); P = 0.04] and transplantation not in CR/PR [HR = 2.20 (95%-CI:0.98-4.95); P = 0.056] reduced PFS. Programmed cell death protein 1(PD-1/PD-L1) treatment before HSCT neither increased GVHD nor impacted survival. We demonstrate that allo-HSCT can achieve long-term survival in approximately half of pts allografted for NKTCL.

The role of transplantation in Hodgkin lymphoma

Despite the success of frontline anthracycline-based chemotherapy for classical Hodgkin Lymphoma (cHL), approximately 15% of patients do not achieve an adequate response and require further therapy. For transplant-eligible patients, additional treatment followed by high-dose chemotherapy and autologous hematopoietic stem cell transplantation (autoHCT) provides a durable response in 50% of patients. The most refractory patients, including those requiring multiple lines of therapy to achieve a response or those relapsing after an autoHCT, may achieve long-term survival with allogeneic hematopoietic stem cell transplant (alloHCT). Contemporary salvage regimens used as a bridge to transplant have expanded to include not only non-cross resistant chemotherapy, but also brentuximab vedotin (BV) and checkpoint inhibitors (CPI). As the management of relapsed/refractory (R/R) cHL evolves with the introduction of novel agents, so too does the role of transplantation. The paradigm of chemosensitivity as a predictor for autoHCT efficacy is being challenged by favorable post- autoHCT outcomes in heavily pre-treated CPI-exposed patients. Contemporary supportive care measures, validated comorbidity assessments, and an increased donor pool with haploidentical donors have broadened the application of transplantation to an increasingly older and diverse patient population. Despite the introduction of increasingly effective treatment options for R/R cHL, transplantation continues to play an important role in the management of these patients. In this review, we explore the impact of salvage therapy on autoHCT, conditioning regimens, maintenance therapy and the diminishing role of alloHCT for patients with cHL.

Outcomes associated with allogeneic hematopoietic stem cell transplantation for relapsed and refractory Hodgkin lymphoma in the era of novel agents

BACKGROUND

Relapsed or refractory Hodgkin lymphoma (R/R HL) is a challenging disease with limited treatment options beyond brentuximab vedotin and checkpoint inhibitors. Herein we present the time-trend analysis of R/R HL patients who received allogeneic hematopoietic cell transplantation (allo-HCT) at our center from 2001-2017.

METHODS

The patients were divided into two distinct treatment cohorts: era1 (2001-2010), and era2 (2011-2017). The primary endpoint was overall survival (OS). Secondary endpoints included progression-free survival (PFS), non-relapse mortality (NRM), and cumulative incidence of acute and chronic graft versus host disease (GVHD).

RESULTS

Among the 51 patients included in the study, 29 were in era1, and 22 were in era2. There was decreased use of myeloablative conditioning in era2 (18% vs. 31%) compared to era1 and 95% of patients in era2 previously received brentuximab Vedotin (BV). Haploidentical donors were seen exclusively in era2 (0% vs. 14%) and more patients received alternative donor transplants (7% vs. 32%) in era2. The 4-year OS (34% vs. 83%, p < 0.001) and 4-year PFS (28% vs. 62%, p = 0.001) were significantly inferior in era1 compared to era2. The incidence of 1-year NRM was lower in era2 compared to era1 (5% vs. 34%, p = 0.06). The cumulative incidence of acute GVHD at day 100 was similar in both eras (p = 0.50), but the incidence of chronic GVHD at 1 year was higher in era2 compared to era1 (55% vs. 21%, p = 0.03).

CONCLUSIONS

Despite the advent of novel therapies, allo-HCT remains an important therapeutic option for patients with R/R HL.

How I prevent GVHD in high-risk patients: posttransplant cyclophosphamide and beyond

Advances in conditioning, graft-versus-host disease (GVHD) prophylaxis and antimicrobial prophylaxis have improved the safety of allogeneic hematopoietic cell transplantation (HCT), leading to a substantial increase in the number of patients transplanted each year. This influx of patients along with progress in remission-inducing and posttransplant maintenance strategies for hematologic malignancies has led to new GVHD risk factors and high-risk groups: HLA-mismatched related (haplo) and unrelated (MMUD) donors; older recipient age; posttransplant maintenance; prior checkpoint inhibitor and autologous HCT exposure; and patients with benign hematologic disorders. Along with the changing transplant population, the field of HCT has dramatically shifted in the past decade because of the widespread adoption of posttransplantation cyclophosphamide (PTCy), which has increased the use of HLA-mismatched related donors to levels comparable to HLA-matched related donors. Its success has led investigators to explore PTCy's utility for HLA-matched HCT, where we predict it will be embraced as well. Additionally, combinations of promising new agents for GVHD prophylaxis such as abatacept and JAK inhibitors with PTCy inspire hope for an even safer transplant platform. Using 3 illustrative cases, we review our current approach to transplantation of patients at high risk of GVHD using our modern armamentarium.

Advances in the treatment of Hodgkin lymphoma: Current and future approaches

Hodgkin lymphoma (HL) is a rare type of lymphoma with unique histologic, immunophenotypic, and clinical features. It represents approximately one-tenth of lymphomas diagnosed in the United States and consists of two subtypes: classical Hodgkin's lymphoma (cHL), which accounts for majority of HL cases, and nodular lymphocyte predominant Hodgkin lymphoma represent approximately 5% of Hodgkin lymphoma cases. From this point, we will be focusing on cHL in this review. In general, it is considered a highly curable disease with first-line chemotherapy with or without the addition of radiotherapy. However, there are patients with disease that relapses or fails to respond to frontline regimens and the standard treatment modality for chemo sensitive cHL is high dose chemotherapy followed by autologous hematopoietic stem cell transplant (AHSCT). In recent years, targeted immunotherapy has revolutionized the treatment of cHL while many novel agents are being explored in addition to chimeric antigen receptor (CAR) T-cell therapy which is also being investigated in clinical trials as a potential treatment option.

Allogeneic hematopoietic stem cell transplantation in Hodgkin lymphoma in Switzerland, 20 years of experience: 2001-2020

Despite the high cure rate with initial therapy, approximately 10% of Hodgkin lymphoma (HL) patients are refractory to initial treatment, and up to 30% of patients will relapse after achieving initial complete remission. Despite promising initial results of treatment by immune checkpoint inhibitors, most patients will eventually progress. We analyzed 62 adult patients with relapsed or refractory HL (rrHL) treated by allogeneic hematopoietic stem cell transplantation (allo-HSCT) in one of three University Hospitals of Switzerland (Zurich, Basel, and Geneva) between May 2001 and January 2020. The primary endpoint was overall survival (OS). Secondary endpoints were relapse-free survival (RFS), non-relapse mortality (NRM), and relapse incidence, which were assessed in univariate analysis. The median follow-up was 61 months (interquartile range 59-139). The 2- and 5-year OS was 54% (standard error (SE) ±12) and 50.2% (SE ±13.3), respectively, and the 2- and 5-year RFS was 40.7% (SE ±16.3) and 34.4% (SE ±19.0), respectively. NRM was 23.1% (SE ±2.2) and 27.4% (SE ±2.5) at 2 and 5 years, respectively. The cumulative incidence of relapse was 36.1% (SE ±5.6) at 2 years and 38.2% (SE ±6.6) at 5 years. Our analysis of allo-HSCT outcomes in the context of rrHL shows encouraging OS and RFS rates, with the mortality rate reaching plateau at 50% at 2 years after allo-HSCT. This confirms that allo-HSCT still remains as a potentially curative option for half of patients with rrHL.

CD25-targeted antibody-drug conjugate camidanlumab tesirine for relapsed or refractory classical Hodgkin lymphoma

Classic Hodgkin lymphoma (cHL) accounts for more than 90% of HL in developed countries. Although the current combined modality therapy make it have a high cure rate, the prognosis for heavily pretreated patients with relapsed or refractory (R/R) cHL remains poor. A novel antibody-drug conjugate (ADC), named camidanlumab tesirine (ADCT-301, Cami), is currently being evaluated for its efficacy and safety in R/R cHL. The primary objective of this review is to examine the current pharmacological properties of camidanlumab tesirine as well as its clinical antitumor activity and safety. Camidanlumab tesirine comprises a human IgG1 anti-CD25 monoclonal antibody HuMax®-TAC, conjugated to a pyrrolobenzodiazepine dimer toxin. Once it bound to CD25-expressing cells, camidanlumab tesirine is internalized by cells and delivers SG3199, then SG3199 irreversibly binds to DNA and forms DNA interstrand crosslinks, ultimately leading to cell death. In the phase 1 study, patients with R/R cHL who received camidanlumab tesirine had an overall response rate (ORR) of 71% and a complete response rate (CRR) of 42%. Additionally, the recommended doses provided in R/R cHL were determined to be 30 and 45 μg/kg. The pivotal phase 2 trial showed significant antitumor activity of camidanlumab tesirine in heavily pretreated R/R cHL patients who failed brentuximab vedotin and programmed death-1 blockade: ORR was 70.1% and CRR was 33.3%, and the median duration of response was 13.7 months. Adverse events such as fatigue, maculopapular rash, and anemia were frequently observed following administration of camidanlumab tesirine. Moreover, camidanlumab tesirine may cause Guillain-Barré syndrome or polyradiculopathy.

Anti-programmed cell death-1 monoclonal antibody therapy before or after allogeneic hematopoietic cell transplantation for classic Hodgkin lymphoma: a literature review

Approximately 10-30% of patients with classic Hodgkin lymphoma (cHL) have relapsed or refractory (r/r) disease after standard first-line therapy. Clinical trials have shown an acceptable safety profile and high response rate for anti-programmed cell death-1 monoclonal antibodies (anti-PD-1 mAbs) in patients with r/r cHL. Although anti-PD-1 mAbs have significantly increased treatment options for r/r cHL, most patients eventually relapse. In the current era, allogeneic hematopoietic cell transplantation (allo-HCT) is still a clinical option for r/r cHL. Anti-PD-1 mAbs have been explored as bridging therapy to allo-HCT and salvage therapy for relapse after allo-HCT. Although early reports showed increased risks of severe graft-versus-host disease (GVHD) in patients who received anti-PD-1 mAb before or allo-HCT, survival outcomes were favorable, suggesting the feasibility of PD-1 blockade around the time of allo-HCT. Based on clinical and biological data, posttransplant cyclophosphamide-based GVHD prophylaxis is a promising strategy to reduce GVHD and improve survival after allo-HCT following PD-1 blockade. Close monitoring and early intervention are needed for treatment-emergent GVHD following PD-1 blockade after allo-HCT. Further studies with a larger cohort and extended follow-up will provide insights into better patient selection, optimal dosing, and strategies to manage complications of PD-1 blockade in the context of allo-HCT.

Favorable outcomes of allogeneic hematopoietic stem cell transplantation with fludarabine-bendamustine conditioning and posttransplantation cyclophosphamide in classical Hodgkin lymphoma

INTRODUCTION

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potentially curative treatment for patients with relapsed and refractory classic Hodgkin lymphoma (rrHL). However, the optimal conditioning regimen and GVHD prophylaxis for rrHL remain undetermined. The aim of this study was to investigate outcomes of allo-HSCT with a fludarabine plus bendamustine (FluBe) conditioning regimen and GVHD prophylaxis with posttransplantation cyclophosphamide (PTCY) in patients with rrHL.

METHODS

Allo-HSCT results in 58 adult patients with rrHL were analyzed retrospectively.

RESULTS

Three-year overall survival and event-free survival were 81% (95% CI 65-91) and 55% (95% CI 38-72), respectively. The cumulative incidence of relapse (CIR) at 3 years was 33% (95% CI 13-51). The cumulative incidence of aGVHD grade II-IV and severe aGVHD grade III-IV was 36% (95% CI 22-48) and 22% (95% CI 9-33), respectively. The cumulative incidence of cGVHD was 32% (95% CI 17-45), including moderate or severe cGVHD in 17% (95% CI 4-28). Patients who developed aGVHD after allo-HSCT had significantly lower CIR (24% vs 49%, p = 0.004). The use of PBSC as a graft source also significantly reduced CIR (4% vs 61%, p = 0.002).

CONCLUSIONS

FluBe-PTCY allo-HSCT facilitates favorable outcomes, low toxicity, and mortality in rrHL.

The outcome of patients with Hodgkin lymphoma and early relapse after autologous stem cell transplant has improved in recent years

Hodgkin lymphoma (HL) patients who relapse after autologous-stem-cell- transplantation (auto-SCT) have traditionally had a poor prognosis. We analyzed 1781 adult HL patients who relapsed between 2006 and 2017 after a first auto-SCT. The 4-year overall survival (OS) after relapse continuously increased from 32% for patients relapsing in 2006-2008, to 63% for patients relapsing in 2015-2017 (p = 0.001). The improvement over time was predominantly noted in patients who had an early relapse (within 12 months) after auto-SCT (p = 0.01). On multivariate analysis, patients who relapsed in more recent years and those with a longer interval from transplant to relapse had a better OS, whereas increasing age, poor performance status, bulky disease, extranodal disease and presence of B symptoms at relapse were associated with a worse OS. Brentuximab vedotin (BV), checkpoint inhibitors (CPI) and second transplant (SCT2; 86% allogeneic) were used in 233, 91 and 330 patients respectively. The 4-year OS from BV, CPI, and SCT2 use was 55%, 48% and 55% respectively. In conclusion, the outcome after post-transplant relapse has improved significantly in recent years, particularly in the case of early relapse. These large-scale real-world data can serve as benchmark for future studies in this setting.

Novel antibodies which have an impact on immune status after allogeneic hematopoietic cell transplantation

INTRODUCTION

In the field of hematological malignancy, we often have the opportunity to use antibodies such as immune checkpoint inhibitors that can alter a patient's immune status before or after allo-HCT. The appropriate use of these novel agents is highly necessary to optimize disease control and reduce the risk of complications associated with adverse allo-immune reactions.

AREAS COVERED

Clinical data on several monoclonal antibodies targeting programmed cell death 1 (PD-1) (nivolumab or pembrolizumab), C-C chemokine receptor 4 (CCR4) (mogamulizumab), CD30 (brentuximab vedotin), or cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) (ipilimumab) are reviewed, with a focus on the incidence and severity of graft-versus-host disease (GVHD).

EXPERT OPINION

While previous studies demonstrated a favorable prognosis in patients who received nivolumab prior to transplantation, the pretransplant use of nivolumab increases the incidence of GVHD, partly due to the expansion and activation of preexisting T cells. Mogamulizumab also has a significant impact on GVHD, caused by persistent depletion of regulatory T cells with CCR4 positivity. Regarding brentuximab vedotin, phase 1 trials have demonstrated considerable efficacy for steroid-refractory acute or chronic GVHD. In the future, sophisticated methods will be needed to determine the impact of each agent on immune status after allo-HCT.

Reappraising the Role of Allogeneic Hematopoietic Stem Cell Transplantation in Relapsed and Refractory Hodgkin’s Lymphoma: Recent Advances and Outcomes

Hodgkin’s lymphoma is a rare yet highly curable disease in the majority of patients treated with modern chemotherapy regimens. For patients who fail to respond to or relapse after initial systemic therapies, treatment with high-dose chemotherapy and autologous hematopoietic stem cell transplantation can provide a cure for many with chemotherapy-responsive lymphoma. Patients who relapse after autologous transplant or those with chemorefractory disease have poor prognosis and represent a high unmet need. Allogeneic hematopoietic stem cell transplantation provides a proven curative therapy for these patients and should be considered, especially in young and medically fit patients. The use of newer agents in this disease such as brentuximab vedotin and immune checkpoint inhibitors can help bring more patients to transplantation and should be considered as well.

Current salvage therapies in Hodgkin lymphoma

Hodgkin lymphoma is a B-cell malignancy with approximately 85-95% complete remission rate following frontline therapy; however, relapsed/refractory disease occurs in roughly 10-30% of patients after treatment. Salvage therapy conventionally relies upon cytotoxic chemotherapy followed by high-dose chemotherapy and autologous stem cell transplantation. A considerable number of patients experience relapse after transplantation, and further salvage management has included the use of allogeneic transplantation and radiotherapy. In the past decade, novel therapies including, brentuximab vedotin, PD-1 inhibitors, and the incorporation of PET-imaging into management have changed the paradigm of relapsed/refractory disease care. Novel therapies have been investigated in both single and combination regimens with other novel therapies and traditional chemotherapies. There is promising early work into the utility of CD30.CAR-T cell therapy, AFM13, camidanlumab tesirine, novel PD-1 inhibitors, and JAK1/JAK2 inhibition in management. Herein, we will review current salvage therapies in Hodgkin lymphoma and future directions in relapsed/refractory disease management.

Double-refractory Hodgkin lymphoma: tackling relapse after brentuximab vedotin and checkpoint inhibitors

The approval of brentuximab vedotin (BV) and checkpoint inhibitors (CPI) has revolutionized the management of relapsed/refractory classical Hodgkin lymphoma (cHL) patients. In recent years these agents have rapidly moved to earlier lines of therapy, including post-autologous hematopoietic cell transplant (auto-HCT) consolidation, pre-HCT salvage, and the frontline treatment setting. This shift in practice means that double-refractory (refractory to both BV and CPI) cHL is becoming an increasingly common clinical problem. In patients who are not eligible for clinical trials, conventional cytotoxic and targeted therapies (off label) may be a potential option. In patients who are transplant eligible, early referral to allogeneic HCT should be considered given the significant improvement in transplant outcomes in the contemporary era. Cellular therapy options including CD30.chimeric antigen receptor T cells, Epstein-Barr virus-directed cytotoxic T cells, and CD16A/30 bispecific natural killer cell engagers appear promising and are currently in clinical trials.

Safety and Efficacy of Pembrolizumab Prior to Allogeneic Stem Cell Transplantation for Acute Myelogenous Leukemia

Programmed death 1 (PD-1) is an integral component of acute myelogenous leukemia (AML) immune evasion, chemotherapy resistance, and disease progression. PD-1 inhibitors are being investigated as treatment for AML in combination with hypomethylating agents and cytotoxic chemotherapy with encouraging findings. Although allogeneic stem cell transplantation (alloSCT) remains the most established curative treatment for patients with relapsed and refractory AML in complete remission, there are limited data on the clinical outcomes and safety of immune checkpoint inhibitors (ICIs) prior to alloSCT in AML. In the present study, we compared clinical outcomes of 9 patients with AML receiving high-dose cytarabine followed by pembrolizumab in a phase II clinical trial (NCT02768792) prior to alloSCT versus a historical control group of 18 AML patients who underwent alloSCT without prior ICI exposure. The nonparametric Jonckheere-Terpstra test was used to test for a difference in the ordered severity categories of acute graft-versus-host disease (GVHD) within 100 days of transplantation. Time-to-event estimates for overall survival and relapse-free survival were calculated using the Kaplan-Meier method and compared using a log-rank test. One-year survival was not significantly different between the treatment groups (67% versus 78%; P = .34). 100-day mortality was 0% in the ICI group versus 17% in the control group, and there was no increase in grade III-IV acute GVHD in patients treated with pembrolizumab prior to alloSCT. No chronic GVHD was seen in patients treated with pembrolizumab prior to alloSCT and who received post-transplantation cyclophosphamide (PTCy) as part of their conditioning regimen. These findings reinforce the safety and feasibility of ICI therapy prior to alloSCT in patients with AML, and suggest that PTCy may abrogate GVHD risk and severity in patients who receive ICI prior to undergoing alloSCT for AML.

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.

Harnessing Treg Homeostasis to Optimize Posttransplant Immunity: Current Concepts and Future Perspectives

CD4⁺CD25⁺Foxp3⁺ regulatory T cells (Tregs) are functionally distinct subsets of mature T cells with broad suppressive activity and have been shown to play an important role in the establishment of immune tolerance after allogeneic hematopoietic stem cell transplantation (HSCT). Tregs exhibit an activated phenotype from the stage of emigration from the thymus and maintain continuous proliferation in the periphery. The distinctive feature in homeostasis enables Tregs to respond sensitively to small environmental changes and exert necessary and sufficient immune suppression; however, on the other hand, it also predisposes Tregs to be susceptible to apoptosis in the inflammatory condition post-transplant. Our studies have attempted to define the intrinsic and extrinsic factors affecting Treg homeostasis from the acute to chronic phases after allogeneic HSCT. We have found that altered cytokine environment in the prolonged post-HSCT lymphopenia or peri-transplant use of immune checkpoint inhibitors could hamper Treg reconstitution, leading to refractory graft-versus-host disease. Using murine models and clinical trials, we have also demonstrated that proper intervention with low-dose interleukin-2 or post-transplant cyclophosphamide could restore Treg homeostasis and further amplify the suppressive function after HSCT. The purpose of this review is to reconsider the distinctive characteristics of post-transplant Treg homeostasis and discuss how to harness Treg homeostasis to optimize posttransplant immunity for developing a safe and efficient therapeutic strategy.

Synchronizing the use of allogeneic hematopoietic cell transplantation in checkpoint blockade therapy for Hodgkin lymphoma

INTRODUCTION

The use of checkpoint blockade therapy (CBT) has shown impressive results for the treatment of relapsed/refractory Hodgkin lymphoma (cHL). The impact of CBT depends on the reversal of an exhausted T-cell immune phenotype and a consequential increase in the immunological, anti-tumor effect derived from a patient's adaptive immunity. As most patients with classical Hodgkin lymphoma will relapse during or after this treatment, clinicians often provide consolidation with allogeneic hematopoietic cell transplantation (alloHCT) in fit patients. However, the mechanisms responsible for CBT efficacy can also be those that increase the risk of immunological complications after alloHCT.

AREAS COVERED

We carried out in-depth research on the current medical literature to report and discuss the mechanism of action of CBT within a cHL setting; clinical results of CBT in cHL setting pre-alloHCT and post-alloHCT; interactions between CBT and alloHCT; and further clinical considerations.

EXPERT OPINION

Checkpoint blockade therapy is an effective strategy for relapsed/refractory cHL. Its use is associated with higher immunological toxicities when administered before or after alloHCT. Whenever alloHCT is planned, clinicians should follow international recommendations such as using post-transplant cyclophosphamide GVHD prophylaxis.

Addition of chemotherapy to nivolumab after PD-1 inhibitor failure as bridge to allogeneic stem cell transplantation in classical Hodgkin's lymphoma: report on three cases and literature review

The poor prognosis of refractory or relapsed (R/R) classical Hodgkin's lymphoma (cHL) after autologous stem cell transplantation has improved greatly due to the introduction of brentuximab vedotin and PD-1 inhibitors. However, the duration of response achieved with these novel agents is too short. The information about the management of patients after anti-PD-1 therapy failure is very limited in cHL, although chemotherapy alone or combined with PD-1 inhibitors has shown encouraging results. We report three cases of heavily pretreated cHL, refractory to nivolumab monotherapy, successfully rescued with the addition of chemotherapy to nivolumab, as a bridge to allogeneic stem cell transplantation (allo-SCT). All three patients presented poor clinical features such as three to four previous lines including brentuximab vedotin and autologous stem cell transplantation, refractoriness to the last line of therapy previous to nivolumab, and rapid disease progression. Notwithstanding these characteristics and nivolumab failure, they achieved a complete response after the addition of chemotherapy, were consolidated with allo-SCT, and still remain in complete response. There are few studies concerning the combination of PD-1 inhibitors and chemotherapy after nivolumab failure, including one retrospective study and one phase II trial with nivolumab plus bendamustine. Therefore, only few patients are consolidated with allo-SCT. However, there are several ongoing trials investigating new combinations of chemotherapy and PD-1 inhibitors in R/R cHL, as well as in first line. All these data suggest that anti-PD-1 therapy may reprogram the immune system, activating and inhibiting effector and immunosuppressive cells, respectively, leading to overtake of chemorefractoriness. Allo-SCT can increase the immune-related events of patients treated with anti-PD-1 previously, consistent on acute graft-versus-host disease, sinusoidal obstruction syndrome, and noninfectious febrile syndrome. In conclusion, the combination of PD-1 inhibitor and chemotherapy may be a feasible therapy after anti-PD-1 treatment failure as a bridge to allo-SCT.

Allogeneic Stem Cell Transplantation for Relapsed and Refractory Hodgkin Lymphoma: Real World Experience of a Single Center

Introduction: Refractory and relapsed Hodgkin lymphoma (R/R HL) is associated with poor prognosis, and allogeneic stem cell transplantation (allo-SCT) remains the only potentially curative approach.

Aim: The aim of the study was to evaluate the feasibility of allotransplantation in R/R HL setting.

Material: Overall, 24 patients (17 men and 7 women) at a median age of 27 years (range 18–44) underwent allo-SCT between 2002 and 2020.

Results: Nineteen patients received prior autologous stem cell transplantation (ASCT1) whereas eight patients received second ASCT (ASCT2) after failure of ASCT1. Six patients received only brentuximab vedotin (BV; n = 4) or BV followed by checkpoint inhibitors (CPI; n = 2) before entering allo-SCT. Median time from ASCT1 to allo-SCT was 17.1 months. Fifteen patients received grafts from unrelated donors. Peripheral blood was a source of stem cells for 16 patients. Reduced-intensity conditioning was used for all patients. Disease status at transplant entry was as follows: complete remission (CR; n = 4), partial response (PR; n = 10), and stable disease (SD; n = 10). Acute and chronic graft-versus-host disease (GVHD) developed in 13 (54%) and 4 (16%) patients, respectively. Median follow-up for the entire cohort was 13.3 months. At the last follow-up, 17 (71%) patients died. The main causes of death were disease progression (n = 10), infectious complications (n = 6), and steroid-resistant GVHD (n = 1). Non-relapse mortality at 12 months was 25%. At the last follow-up, seven patients were alive; six patients were in CR, and one had PR. The 2-year overall survival (OS) was 40%.

Conclusion: Chemosensitive disease at transplant was associated with better outcome. Allo-SCT allows for long-term survival in refractory and relapsed HL.

Latest advances in the management of classical Hodgkin lymphoma: the era of novel therapies

Hodgkin lymphoma is a highly curable disease. Although most patients achieve complete response following frontline therapy, key unmet clinical needs remain including relapsed/refractory disease, treatment-related morbidity, impaired quality of life and poor outcome in patients older than 60 years. The incorporation of novel therapies, including check point inhibitors and antibody-drug conjugates, into the frontline setting, sequential approaches, and further individualized treatment intensity may address these needs. We summarize the current treatment options for patients with classical Hodgkin lymphoma from frontline therapy to allogeneic hematopoietic stem cell transplantation and describe novel trials in the field.

Therapeutic Use of Valproic Acid and All-Trans Retinoic Acid in Acute Myeloid Leukemia-Literature Review and Discussion of Possible Use in Relapse after Allogeneic Stem Cell Transplantation

Even though allogeneic stem cell transplantation is the most intensive treatment for acute myeloid leukemia (AML), chemo-resistant leukemia relapse is still one of the most common causes of death for these patients, as is transplant-related mortality, i.e., graft versus host disease, infections, and organ damage. These relapse patients are not always candidates for additional intensive therapy or re-transplantation, and many of them have decreased quality of life and shortened expected survival. The efficiency of azacitidine for treatment of posttransplant AML relapse has been documented in several clinical trials. Valproic acid is an antiepileptic fatty acid that exerts antileukemic activity through histone deacetylase inhibition. The combination of valproic acid and all-trans retinoic acid (ATRA) is well tolerated even by unfit or elderly AML patients, and low-toxicity chemotherapy (e.g., azacitidine) can be added to this combination. The triple combination of azacitidine, valproic acid, and ATRA may therefore represent a low-intensity and low-toxicity alternative for these patients. In the present review, we review and discuss the general experience with valproic acid/ATRA in AML therapy and we discuss its possible use in low-intensity/toxicity treatment of post-allotransplant AML relapse. Our discussion is further illustrated by four case reports where combined treatments with sequential azacitidine/hydroxyurea, valproic acid, and ATRA were used.