Why Mirati Therapeutics Shares Are Nosediving

Mirati Therapeutics Inc MRTX shares are trading lower by 4.90% to $41.70 after Citigroup downgraded the stock from Buy to Neutral. 

Shares are also lower on continued weakness after the company announced late-breaking results evaluating concurrent adagrasib and pembrolizumab in first-line advanced/metastatic non-small cell lung cancer.

What Happened?

Early data shows that a combination treatment demonstrated promising preliminary clinical activity across all PD-L1 subgroups with an objective response rate (ORR) of 49%, with a manageable safety profile.

Mirati Therapeutics says 75 patients were enrolled and evaluable for safety with a median follow-up of 3.5 months (duration of treatment: 2 months). Treatment-related adverse events (TRAEs) were Grade 1-2 (39%), Grade 3 (40%) and Grade 4 (4%); the company says there were no Grade 5 TRAEs observed.

TRAEs led to discontinuation of both adagrasib and pembrolizumab in 2 patients and only pembrolizumab in 2 patients; there were no patients who discontinued only adagrasib due to a TRAE.

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The company says Adagrasib is an investigational, highly selective, and potent oral small-molecule inhibitor of KRASG12C that is optimized to sustain target inhibition, an attribute that could be important to treat KRASG12C-mutated cancers, as the KRASG12C protein regenerates every 24-48 hours. Studies of adagrasib have shown that the drug has a long half-life and extensive tissue distribution, and is well tolerated.

"We remain committed to developing our portfolio of oncology candidates and advancing our lung cancer strategy to positively impact the lives of patients with cancer. We look forward to providing an update based on the full analysis of the SAPPHIRE study in mid-2023," said Charles Baum, M.D., Ph.D., president, founder and head of research and development, Mirati Therapeutics.

According to data from Benzinga Pro, MRTX has a 52-week high of $154.17 and a 52-week low of $32.96.