Biodesix, Inc. announced initial results of their proteomic analysis of GlobeImmune’s Phase 2 adjuvant trial of GI-4000 plus gemcitabine (Gemzar; Lilly, Eli and Company) vs. gemcitabine alone in ras mutation+ resected pancreatic cancer.

The trial was designed to evaluate the impact of GI-4000 on patients’ recurrence-free survival. The companies collaborated to evaluate Biodesix’ ProTS mass spectrometry-based technology platform in the identification of a proteomic signature that could identify patients who were more likely to have good outcomes following GI-4000 therapy. The collaboration was also a demonstration of ProTS’ ability to rapidly identify clinically meaningful signatures based on analysis of patient blood-derived samples.

The GlobeImmune study enrolled subjects with Ras mutant positive adenocarcinoma of the pancreas post resection randomized 1:1 to GI-4000 plus gemcitabine or placebo plus gemcitabine (stratified by R0 or R1 resection status). Results of this clinical study demonstrated a 2.6 month improvement in median overall survival in R1 subjects treated with GI-4000 in combination with gemcitabine (17.2 months) versus subjects treated with gemcitabine and placebo (14.6 months), a 16% advantage in 1 year survival (72% vs. 56%), and a 1 month advantage in median RFS (9.6 vs. 8.5 months).

Exploratory proteomic analysis using MALDI ToF mass-spectrometry and ProTS was performed by Biodesix on baseline plasma samples from patients in the study. This analysis revealed a proteomic signature that was associated with improved clinical outcomes in the GI-4000 treated group, but not in the placebo group. The exploratory proteomic signature was observed in approximately half of tested study subjects (16 of 44 in the GI-4000 group and 26 of 46 in the placebo group). The specific proportion of patients could change with further development of the diagnostic test. This signature could, if prospectively validated, have the potential for use as an enrichment marker in future clinical trials.

GI-4000 is a series of four product versions; each version is a heat-inactivated S. cerevisiae yeast expressing a unique combination of three Ras mutations, collectively targeting seven of the most common Ras mutations observed in human cancers.  

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