A phase 2 trial evaluating the use of a vaccination-based method to promote secretion of granulocyte-macrophage colony-stimulating factor (GM-CSF) in patients who underwent allogeneic hematopoietic stem cell transplantation (alloHSCT) showed the method to be well tolerated. However, improved progression-free survival (PFS) was not seen. Trial results were reported in the journal Blood Advances.
The method under examination involved a vaccine containing irradiated, adenovirus-transduced autologous myeloblasts (GVAX) to promote secretion of GM-CSF. An objective of the study was to use GVAX to potentially help induce antitumor immunity.
In this multicenter, double-blind trial (ClinicalTrials.gov Identifier: NCT01773395), patients having either myelodysplastic syndrome (MDS) with excess blasts or relapsed/refractory acute myeloid leukemia (AML) were randomized to receive either GVAX or a placebo following allogeneic HSCT. Treatments were given over the course of 6 vaccinations. The first vaccination was to be given between days 30 and 45 following HSCT if engraftment occurred and in the absence of grade 2 to 4 acute GVHD requiring systemic steroids, in addition to other criteria. Tacrolimus and methotrexate were used for graft-versus-host disease (GVHD) prophylaxis. The 18-month PFS rate was the primary end point.
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There were 123 patients enrolled, of whom 92 proceeded to alloHSCT. At least 1 vaccination was administered in 30 patients receiving GVAX and in 27 receiving placebo. The median follow-up was 39 months (range, 9-89).
The 18-month PFS rates were 53% with GVAX and 55% with placebo (P =.79). The 18-month overall survival rates were 63% for GVAX and 59% for placebo (P =.86), and the 18-month relapse rate was 30% with GVAX, compared with 37% with placebo (P =.51). The 18-month nonrelapse mortality rates were also statistically similar between treatments, at 17% with GVAX and 7.7% with placebo (P =.18).
Injection-site reactions occurred more often in the GVAX arm (P =.006). The GVAX arm reported 2 grade 3 nonhematologic adverse events that were deemed possibly related to vaccination. The 1-year rates of acute GVHD of grades 2 to 4 were 34% with GVAX and 12% for placebo (P =.13). The 3-year cumulative incidence of chronic GVHD was 49% with GVAX, and it was 57% with placebo (P =.26).
The study investigators also reported that GVAX was not associated with enhancement or weakening of reconstitution of T, B, or natural killer cells. Additionally, GVAX was not associated with changes in immune biomarker profiles.
The investigators concluded that the method used in this study was feasible and that GVAX appeared to be safe. However, it was not linked to improvements in relapse or relapse-free survival following HSCT.
“Despite the disappointing clinical results of this and other GVAX randomized trials to date, these studies continue to teach us much about the subtleties of tumor immunity, and highlight the challenges of performing large randomized autologous leukemia vaccination trials, especially in the alloHSCT setting,” the study investigators wrote in their report.
Disclosures: Some authors have declared affiliations with or received grant support from the pharmaceutical industry. Please refer to the original study for a full list of disclosures.
Reference
Ho VT, Kim HT, Brock J, et al. GM-CSF secreting leukemia cell vaccination for MDS/AML after allogeneic HSCT: a randomized, double-blinded, phase 2 trial. Blood Adv. 2022;6(7):2183-2194. doi:10.1182/bloodadvances.2021006255
