Galinpepimut-S Safe and Effective in Multiple Myeloma

Phase 2 clinical and immunological data presented at the 44^th Annual European Society for Blood and Marrow Transplantation (EBMT) Meeting this morning revealed that galinpepimut-S (GPS) is safe and effective in high-risk multiple myeloma (MM).

The novel WT1 gene-targeting direct immunizer was evaluated as consolidation therapy to potentially stimulate a highly-specific immune response against WT1 to prevent or delay myeloma progression.

The results showed that median progression-free survival (PFS) in the high-risk disease setting was 23.6 months, compared to historically inferior outcomes of patients on an immunomodulatory drug (IMID) or proteasome inhibitor post-autologous stem cell transplant (ASCT) maintenance.

In the study, 19 patients who had high-risk cytogenesis at diagnosis and achieved a stable disease or better status following ASCT were enrolled. Those who still exhibited at least measurable minimal residual disease were administered GPS.

“These results are encouraging particularly given the patients’ poor prognosis due to their high-risk cytogenetic profile at disease presentation and their still harboring minimal residual disease prior to GPS treatment”, said Angelos M. Stergiou, M.D., Sc.D. h.c., President and CEO of Sellas in a press release. “The improved PFS at 23.6 months in this setting instills further confidence in our advancing GPS development as an important immuno-therapeutic treatment option for aggressive multiple myeloma.”

In the study, it was discovered that clinical activity was linked to antigen-specific immune responses. Additionally, GPS stimulated time-dependent and robust CD4+ T cell or CD8+ T cell immune responses (IRs) specific for all 4 WT1 peptides within GPS, two of which are hetereoclitic. Additionally, the GPS data suggest a distinctive link between clinical and immune responses, which had not been previously described for a peptide vaccine in MM.

“High-risk multiple myeloma is a disease subset with high potential of short-term disease progression following autologous stem cell transplants, providing opportunities to improve on this limited clinical outcome. We are seeing an encouraging signal from GPS in our Phase 2 study with progression-free survival (PFS) exceeding historical outcomes with standard therapies,” stated Guenther Koehne, M.D., Ph.D., the Principal Investigator on the study.

“Currently, post-transplant maintenance therapies for these difficult-to-treat patients are seemingly limited, with PFS rarely exceeding 12-14 months.”

Other key data findings from the study included that GPS stimulated time-dependent and robust CD4+ T cell or CD8+ T cell immune responses (IRs) specific for all four WT1 peptides, and that it stimulated similar IRs against 2 counterpart native peptides. The data suggest a distinctive link between clinical responses and IRs, which had not previously been described for a peptide vaccine in MM.

Because the WT1 antigen is overexpressed in many malignancies and it is not found in most normal tissues, GPS has the potential to be a broad immunotherapy, effective across several different cancer types and patient populations.

Those interested can access Dr. Koehne’s complete EBMT presentation covering the GPS results here.

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