Mirati's adagrasib spurs 41% response in pancreatic, GI tumors, scoring points over KRAS leader Amgen

Mirati Therapeutics' KRAS drug adagrasib led to a 41% response rate in patients with pancreatic and other gastrointestinal tumors, the latest in the biotech's efforts to eke out an edge against the big winner in the drug class, Amgen. 

Rival Amgen beat Mirati into the KRAS-inhibitor market with Lumakras, which was approved in non-small cell lung cancer last May. Mirati is awaiting an FDA approval for adagrasib in NSCLC next quarter, which will set up a game of catch up. 

While Amgen may have crossed the regulatory finish line first in lung cancer, Lumakras hasn't fared as well as Mirati's adagrasib in colorectal cancer. Friday's data in pancreatic and GI tumors could pad adagrasib's stance against Amgen in these indications.

The data presented Friday gives the San Diego biotech confidence to "continue to aggressively evaluate adagrasib," said Charles Baum, M.D., Ph.D., founder, president and head of R&D, in a statement. 

RELATED: Seeking an edge over Amgen, Mirati advances lower KRAS dose in Keytruda combo to improve tolerability

The phase 2 KRYSTAL-1 study featured patients with cancers of the biliary tract, appendix, small bowel, gastro-esophageal junction, and esophagus, who have a mutation of the KRAS gene. Mirati disclosed the findings at the 2022 American Society for Clinical Oncology Gastrointestinal Cancers Symposium on Friday.

A specific breakdown of adagrasib's impact shows the drug worked better in patients with pancreatic cancer than those with other GI tumors in the subset of the Krystal-1 study. Patients with pancreatic cancer notched a 50% objective response, whereas others with GI cancers achieved a 35% response. Patients responded for a median of seven months and 7.9 months, respectively. 

The disease control rate was 100% across the 27 patients in the subset. Patients with pancreatic cancer did not see the progression of their disease for a median of 6.6 months and for GI tumors, the duration was 7.9 months. 

The drug led to grade 3/4 treatment-related adverse events in 27% of patients, with none leading patients to stop treatment. 

RELATED: UPDATED: 6 weeks in, Mirati CEO shows CMO, COO the door ahead of key FDA filing for KRAS drug

“Adagrasib is going to be a very big drug for a very long time,” said David Meek, recently installed CEO, at last week's J.P. Morgan Healthcare Conference. 

Meek did not waste time reshuffling his team six weeks into his tenure as CEO last fall. He showed the exit to Chief Medical Officer Joseph Leveque, M.D., and Chief Operating Officer Daniel Faga in late October, causing shares to drop 15% to $161.40 apiece on Nov. 1. Shares have continued sliding since then, dropping slightly to $117.94 as of 11:25 a.m. ET on Friday.

Editor's note: This article was updated at 1:49 p.m. ET on Feb. 2 to clarify indications that Amgen's KRAS drug is being studied in.