- Mirati Therapeutics' experimental cancer drug adagrasib helped shrink tumors in 45% of patients with relapsed lung cancer in a small trial, according to Phase 1/2 study data released Sunday, raising hopes the pill may outperform Amgen's more-advanced competitor, sotorasib.
- Seven of 14 patients in the Phase 1 portion of the trial were still on treatment after more than six months, suggesting adagrasib could compete with sotorasib on survival measures, which regulators view as the most important criteria when evaluating new cancer drugs. However, some patients taking Mirati's pill had a heart rhythm irregularity that could prompt regulators to look more closely at safety data.
- Both Amgen and Mirati could ask the Food and Drug Administration to approve their respective drugs next year. Release of Mirati's data, which was presented at a cancer specialists' virtual meeting this weekend, sent shares in the company higher by 14% Monday.
Both Amgen's and Mirati's drugs target a protein called KRAS, which in its mutated form is a driver of a number of forms of cancer. KRAS had previously been viewed as "undruggable" because it has few places onto which drugs can bind.
Amgen, however, found an amino acid that sotorasib could lock onto, allowing the company to advance sotorasib further than any other would-be KRAS drug before it.
Mirati is part of a wave of rivals looking to replicate Amgen's success, and the data from its Phase 1/2 trial, released at a meeting sponsored by the National Cancer Institute and two leading oncology research associations, suggested the biotech has a good chance of doing that.
The lung cancer patients in Mirati's study had previously received a median of two previous treatments before adagrasib. In the Phase 1 portion of the trial, 43% of the patients saw their tumors shrink, and in Phase 2, 62% did. None of the patients experienced a complete remission, however.
Amgen's sotorasib, by comparison, shrank tumors in 32% of a larger group of lung cancer patients. Treatment helped lung cancer patients live a median of four months before their disease progressed, according to the data.
Previous results for sotorasib, among fewer patients, showed a response rate as high as 50%.
Mirati also detailed data for adagrasib in colorectal cancer, but those looked less promising. Only 17% of patients in that Phase 1 trial saw their tumors shrink.
Heart rhythm irregularities were observed in 14% of the electrocardiograms of patients in the lung cancer trial. Mirati executives told analysts there were no cases of actual heart arrhythmias, and all irregularities resolved after pausing treatment with adagrasib.
Nonetheless, such heart rhythm irregularities are a concern of the FDA, which could slow adagrasib's development if the agency asks for closer study of the drug's cardiovascular effects before it considers a review.
Meanwhile, Mirati's next step with the Phase 2 trial is to test adagrasib in combination with other lung cancer drugs, starting with Merck & Co.'s Keytruda. Executives said that portion of the trial has cleared a safety observation period and patients are now receiving the full dose of both drugs.