GM-CSF secreting leukemia cell vaccination for MDS/AML after allogeneic HSCT: a randomized double blinded phase 2 trial.

Vaccination using irradiated, adenovirus transduced autologous myeloblasts to secrete GM-CSF (GVAX) early after allogeneic hematopoietic stem cell transplantation (HSCT) can induce potent immune responses. We conducted a randomized phase II trial of GVAX after HSCT for MDS-EB or relapsed/refractory AML. Myeloblasts were harvested before HSCT to generate the vaccine. Randomization to GVAX vs. placebo (1:1) was stratified by disease, transplant center, and conditioning. GVHD prophylaxis included tacrolimus and methotrexate. GVAX or placebo started between day +30-45 if there was engraftment and no GVHD. Vaccines were administered SC/ID weekly x 3, then q2 wks x 3. Tacrolimus taper began after vaccine completion. 123 patients enrolled, 92 proceeded to HSCT, and 57 (GVAX 30, Placebo 27) received at least 1 vaccination. No CTC grade ≥ 3 vaccine related adverse events were reported, but injection site reactions were more common after GVAX (10 vs. 1, p=0.006). With a median follow up of 39 months (range, 9-89), 18-month PFS, OS and relapse incidence were 53% vs 55% (p=0.79), 63% vs. 59% (p= 0.86), and 30% vs. 37% (p=0.51) for GVAX and placebo, respectively. NRM at 18 months was 17% vs. 7.7% (p=0.18), Grade II-IV aGVHD at 12 months 34% vs. 12% (p=0.13), and cGVHD at 3 years 49% vs. 57% for GVAX and placebo, respectively, p=0.26. Reconstitution of T, B, and NK cells were not decreased or enhanced by GVAX. There were no differences in serum MICA/B or other immune biomarkers between GVAX and placebo. GVAX does not improve survival after HSCT for MDS/AML. (Clinicaltrials.gov identifier: NCT01773395).