Health South Florida
Guenther Koehne, MD, PhD Photo courtesy of Baptist
LISBON—Post-transplant therapy including galinpepimut-S (GPS) may prolong progression-free survival (PFS) in patients with high-risk multiple myeloma (MM), according to new research.
In a phase 2 trial, MM patients who received GPS and lenalidomide or bortezomib after autologous stem cell transplant (ASCT) had a median PFS of 23.6 months.
“Currently, post-transplant maintenance therapies for these difficult-to-treat patients are seemingly limited, with PFS rarely exceeding 12 to 14 months,” said Guenther Koehne, MD, PhD, from Miami Cancer Institute of Baptist Health South Florida.
Dr Koehne presented results observed with lenalidomide/bortezomib maintenance plus GPS consolidation at the 44th Annual Meeting of the EBMT (abstract OS4-6).
The trial was supported by the Leo A. Guthart and Kathryn Medina Research Fund and SELLAS Life Sciences Group, the company developing GPS.
The study enrolled 19 MM patients. Fifteen of them had high-risk cytogenetics at diagnosis, and 18 were at least minimal residual disease-positive after ASCT.
The goal of GPS therapy was to stimulate an immune response to prevent or delay MM progression. GPS is a cancer immunotherapeutic consisting of 4 modified peptide chains that induce an innate immune response against the WT1 antigen.
Patients began receiving GPS within 22 days of ASCT. They received 6 doses, administered subcutaneously with the oil emulsifier montanide every 2 weeks. Injection sites were pre-stimulated with granulocyte-macrophage colony-stimulating factor (70 μg) on days -2 (± 1 day) and 0 of each GPS vaccination.
The patients underwent clinical, immune response, and correlative assessment 2 to 4 weeks after the 6th GPS dose. Then, they received 6 additional monthly doses of GPS as well as lenalidomide (n=18) or bortezomib (n=1) maintenance, starting on day 100 post-ASCT. They underwent clinical, immune response, and correlative assessment again, 2 to 4 weeks after the 12th GPS dose.
Results
Dr Koehne said GPS stimulated time-dependent CD4+ or CD8+ T-cell immune responses specific for all 4 WT1 peptides within GPS, 2 of which are heteroclitic.
Immune responses were confirmed in up to 91% of patients, with multivalent immune responses in up to 64% of patients. And 75% of patients had multifunctional cross-epitope T-cell reactivity to antigenic epitopes against which the hosts were not specifically immunized, in a pattern akin to epitope spreading.
Dr Koehne also said immune responses were linked to clinical activity. In patients who received all 12 doses of GPS (n=12), there was a “strong and bidirectional association” between clinical benefit—defined as complete response (CR) or very good partial response (VGPR)—and frequency of CD4/CD8 immune responses.
Of those patients who had achieved CR/VGPR upon completion of GPS treatment, 100% (n=11) had CD4 immune responses and 81.8% (n=9) had CD8 immune responses.
Among patients who maintained immune response positivity, the CR/VGPR rate was 54.6% if CD4 immune response positivity to any of the 4 native GPS peptides was maintained and 44.0% if CD8 immune response positivity to any of the 4 native GPS peptides was maintained.
The PFS was 81% at 12 months and 62% at 18 months. The median PFS was 23.6 months (range, 15.2 to not reached).
The overall survival was 88% at 18 months, and the median overall survival was not reached.