BioPharma

Mirati presents data on drug with tough-to-reach target, setting up competition with Amgen

An analyst noted that Mirati's MRTX849, a KRAS G12C inhibitor, is six to nine months behind Amgen's AMG 510, but that the market has room for both. The data presented were on patients with lung and colorectal cancers.

Amgen’s drug for an “undruggable” cancer target had its first data out earlier this year, but its already got some potential competition.

San Diego-based Mirati Therapeutics announced Monday the presentation of data from the Phase I/II study of its KRAS G12C inhibitor, MRTX849, showing clinical activity that included objective responses in patients with non-small cell lung cancer and colorectal cancer. The data were presented at the 2019 AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics in Boston.

Shares of Mirati rose 16.5 percent on the Nasdaq Tuesday morning following the news. Amgen is developing the drug AMG 510, which is also a KRAS G12C inhibitor that has shown encouraging early data.

“Patients whose tumors carry the KRAS G12C mutation have a poor prognosis, are resistant to standard-of-care treatment and have no available targeted therapeutic options,” Mirati CEO Charles Baum said in a statement. “Early efficacy and safety data from this Phase I/II trial demonstrate the potential of a potent and effective KRAS therapy.”

Mirati’s trial has so far enrolled 17 patients, including 10 with NSCLC, four with CRC and three with other tumors. Across all dose levels, three of six patients with NSCLC and one of four with CRC achieved a partial remission – meaning partial disappearance of their tumor – with one from each group having a confirmed partial response. At the highest dose level, 600mg, three of five with NSCLC and one of two with CRC achieved a partial response, while the rest experienced stable disease. Most treatment-related adverse events were low-grade in nature, with two patients experiencing dose-limiting toxicities. The maximum tolerated dose had not been established.

In a note to investors Monday, Oppenheimer analysts Silvan Tuerkcan and Jay Olson wrote that they were optimistic about the initial data on MRTX849 based on a Phase I study design that leads to more patients on the highest dose, potential to transition from a Phase I to a Phase II registration study under the existing protocol, and future combinations like with immune checkpoint inhibitors in NSCLC.

However, Cowen analyst Yaron Werber wrote that while similarities in efficacy between MRTX849 and AMG 510 made room for both drugs on the market, the former was unlikely to beat the latter to market due to being six to nine months behind in development, with a heavier pill burden and twice-daily dosing.

Data for AMG 510 presented at the European Society for Medical Oncology last month included 55 patients, including 29 with CRC and 12 who received the target dose of 960mg once daily. Among those 12 patients, one experienced a partial response, while 10 had stable disease. Still, Werber wrote at the time that while the data showed the drug is active, the overall response rate was below the 10-20 percent he and colleagues had expected and the 20-30 percent rate required to support the drug’s development as a single-agent therapy.

Photo: nopparit, Getty Images

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