Immunotherapy following relapse of acute leukaemia after T-cell-replete allogeneic peripheral blood progenitor cell transplantation: importance of new onset chronic graft-versus-host disease

Pegylated interferon-2α invokes graft-versus-leukemia effects in patients relapsing after allogeneic stem cell transplantation

Allogeneic stem cell transplantation (SCT) is a curative therapy for patients with hematological malignancies related largely to an immunological graft-versus-leukemia (GVL) effect mediated by donor T cells and natural killer cells. Relapse of disease after SCT represents failure of GVL and is now the major cause of treatment failure. We sought to augment GVL effects in patients (n = 29) relapsing after SCT in a prospective phase I/II clinical trial of dose-escalated pegylated interferon-2α (peg-IFNα). The administration of peg-IFNα after reinduction chemotherapy, with or without subsequent donor lymphocyte infusion (DLI), resulted in a 2-year overall survival (OS) of 31% (95% confidence interval, 17.3%-49.2%), which rejects the null hypothesis of 7% generated by observations in an institutional historical cohort. As expected, peg-IFNα was associated with graft-versus-host disease (GVHD) and hematological toxicity, which was manageable with scheduled dose modifications. Progression-free survival (PFS) was greatest in patients who experienced GVHD, although the majority of those patients still eventually progressed. Higher PFS and OS were associated with pretreatment proportions of immune cell populations with regulatory function, including mucosal invariant T cells, regulatory T cells, and plasmacytoid dendritic cells, independent of any association with GVHD. Peg-IFNα administration after relapse thus constitutes a logical strategy to invoke GVL effects and should be studied in a larger, multicenter cohort. This trial was registered at www.anzctr.org.au as #ACTRN12612000728831.

New Strategy of Acute Graft-vs-Host Disease: Investigation of a Reduced Dose of Antithymocyte Globulin in Haploidentical Hematopoietic Stem Cell Transplantation

Graft-vs-host disease (GVHD) is one of the biggest challenges in haploidentical hematopoietic stem cell transplantation. Antithymocyte globulins (ATGs) are widely used to overcome GVHD, but excessive immunosuppression increases the chances of relapse and infection following transplantation. No defined standard of the appropriate dose of ATG usage is recognized. The study included 11 patients who were treated with a reduced dose of ATG to prevent GVHD in haploidentical hematopoietic stem cell transplantation. A reduced dose of ATG-Thymoglobulin (total dose of 5 mg/kg) was used in the pretreatment protocol for 2 consecutive days. All patients had successful transplantation. The median time of neutrophil engraftment was 12 days. All chimerism tests passed on day 30, 60, and 90 post transplantation. None of the patients had acute GVHD, while only 2 patients had I to II degree chronic GVHD (18.2%). No transplantation-related deaths were observed. The current findings suggest that the reduced dose of ATG can effectively prevent the incidence of acute GVHD in haploidentical hematopoietic stem cell transplantation.

Lymphodepleting chemotherapy with donor lymphocyte infusion post-allogeneic HCT for hematological malignancies is associated with severe, but therapy-responsive aGvHD

Donor lymphocyte infusion (DLI) is an option for relapsed hematologic malignancies or incomplete chimerism of non-malignant diseases following allogeneic hematopoietic cell transplantation (HCT). We analyzed the incidence of acute graft versus host disease (aGVHD) in patients treated with DLI. From 1995-2013, 171 DLIs were given to 120 patients. The cumulative incidence of post-DLI grade II-IV aGVHD was 31.6% (CI 25-42%, n=40; 12 grade II); grade III-IV 23.3% (CI 16-32%, n=28). GVHD after DLI (n=46) involved the skin in 70% (n=32), lower gastrointestinal (GI) 65% (n=30), upper GI 43% (n=20), and liver 35% (n=16). Patients receiving chemotherapy accompanying the DLI (chemo-DLI)(n=37) had more frequent aGVHD and particularly lower GI GVHD. Risk factors for grade II-IV aGVHD included: age > 40, chemo-DLI, malignant disease, and time from HCT to DLI < 200 days. aGVHD response to treatment at 8 weeks was complete in 40% and complete/partial (CR/PR) in 52%.

We observed frequent, yet therapy-responsive aGVHD following DLI. Gastrointestinal GVHD in particular is a significant risk when giving chemotherapy prior to DLI. Improvements in DLI efficacy and GVHD management are still needed.

New strategies of DLI in the management of relapse of hematological malignancies after allogeneic hematopoietic SCT

DLI is an effective strategy for patients with recurrent hematological malignancies after allogeneic hematopoietic SCT (allo-HSCT). DLI has been widely applied to boost the graft vs tumor (GVT) or GVL effects. However, given the potentially severe complications associated with conventional DLI and transient GVL effect, new strategies for DLI are emerging. In this review, we have discussed the recent important studies on DLI as a prophylactic or therapeutic modality for relapsed hematological disorders after allo-HSCT. The strategies to separate GVL from GVHD have also been discussed. Leukemia-targeting therapy and lymphodepletion combined with DLI, and prophylactic DLI after allo-HSCT are often employed for patients with high risk of relapse, which has been reviewed as well. In addition, we have also discussed the issues on DLI to be further addressed, such as the doses, timing and frequency of DLI in different clinical settings, leukemic antigen-specific DLI as well as how to augment GVL effect while attenuating GVHD.