Tuesday, Gritstone Bio Inc ( GRTS ) released preliminary data from the ongoing, signal-seeking Phase 2 portion of the Phase 2/3 study evaluating GRANITE, its personalized neoantigen cancer vaccine, in front-line metastatic microsatellite stable colorectal cancer (MSS-CRC). 

The study is designed to quantify the clinical benefit of maintenance therapy with GRANITE (GRT-C901/GRT-R902) in combination with immune checkpoint blockade in addition to fluoropyrimidine/bevacizumab versus fluoropyrimidine/bevacizumab alone. 

Overall progression-free survival (PFS) data show an early trend in benefit for GRANITE patients with a hazard ratio of 0.82 and extended PFS benefit in high-risk patients with a hazard ratio of 0.52, in whom progression occurs faster. 

Circulating tumor DNA (ctDNA) analysis over several months of treatment shows the expected relationship with disease progression and favors GRANITE, while short-term ctDNA response analysis did not demonstrate a difference between study arms. 

Gritstone bio manufactured the GRANITE product candidate for every eligible patient (i.e., 100% vaccine manufacturing success rate).

GRANITE demonstrated a favorable safety and tolerability profile. Common AEs were mild systemic and local effects typically associated with any potent vaccine (i.e., transient flu-like illness). No patients discontinued study treatment due to an AE.

Concurrently, on Monday, Gritstone bio priced the approximately $32.5 million underwritten public offering of 8.33 million shares and accompanying common warrants to purchase 8.33 million shares at a combined price of $1.50.

Last month, Gritstone bio announced an approximately 40% reduction of its workforce. 

The move comes following the recently announced delay of the proposed CORAL Phase 2b study, which resulted in Gritstone not receiving the external funding it previously anticipated, beginning in the first quarter of 2024, associated with the initiation of the study. 

Price Action: GRTS shares are down 43% at $1.34 on the last check Tuesday.