GV1001 is a human telomerase reverse transcriptase catalytic subunit class II 16mer peptide vaccine. A phase 2 trial in advanced pancreatic cancer showed a total immune response in 24 (63%) of 38 patients. The combination of gemcitabine and capecitabine is a standard of care for patients with pancreatic cancer. The design of the TeloVac study was based on the clear clinical evidence of immunogenicity of GV1001 in patients with pancreatic cancer, the available preclinical data showing the synergy of gemcitabine with cancer vaccines and the other positive immunomodulatory effects of gemcitabine and fluoropyrimidines.
An accompanying Comment article notes that despite the negative findings, this well conducted study does provide a salutary reminder that compromising any aspect of conventional treatment can be risky when testing new combinations. This trial substantially shortened the duration of chemotherapy in the sequential group, despite modest evidence for single-agent efficacy of the vaccine and an accepted standard of care which recommends chemotherapy to remain ongoing until disease progression, or occurrence of toxic effects. This decision may have compromised the efficacy of the sequential group, and does not allow a meaningful comparison between sequential and concurrent administration of the vaccine.