ESMO: Amgen KRAS colon cancer data disappoint

Big Biotech Amgen saw a stronger response from its recent lung cancer data. (Amgen)

In lung cancer, Amgen’s buzzy KRAS drug hit the heights. But in its latest update at the European Society of Medical Oncology (ESMO) meeting over the weekend, it didn't follow suit in colon cancer.

Amgen was testing its drug, known as AMG 510, in an early-stage, phase 1 focused on patients with previously treated KRAS G12C-mutant solid tumors.

There were 76 patients in all, but in an analysis presented at the ESMO annual congress, focus was on the subset of evaluable colorectal cancer (CRC) patients who could take the highest 960 mg dose, which was an even dozen.

Of these 12, only one patient saw a partial response (PR), and 10 had stable disease for a disease control rate of 92%. There were no major adverse safety worries attached to the test.

The study also looked at patients with several different cancers: Thirteen of the evaluable patients with non-small cell lung cancer (NSCLC) received the highest dose, of which seven (54%) hit a PR at one or more time points and six (46%) achieved stable disease, for a disease control rate of 100%.

“Data across dosing cohorts also showed tumor responses in two evaluable patients with appendiceal cancer with one partial response and one experiencing stable disease,” Amgen said in a release from Spain.

Just a few weeks back, Amgen posted new data on AMG 510 in NSCLC at the World Conference on Lung Cancer that was much more encouraging.

This included 23 evaluable NSCLC patients with 13 taking the target dose, i.e., 960 mg. The drug kept cancer at bay in 100% of lung cancer patients and shrank tumors in more than half of them.

Amgen was hopeful the benefit could translate into CRC, but the one PR isn’t nearly as impressive. While a common oncogene driving several of the biggest killing cancers, KRAS is a tough target, one previously seen as “undruggable,” and has generated a lot of coverage this year as Amgen appeared to have a good angle on it.

RELATED: Amgen's KRAS drug continues to deliver but faces 'curse' of high expectations

Management, for its part, was keeping upbeat around the ESMO performance. “KRAS is the most frequently mutated oncogene in human tumors. Although KRASG12C has been a formidable target for nearly four decades, we can now report responses in patients with non-small cell lung, colorectal and appendiceal cancers,” Amgen R&D chief David Reese said in a statement.

The company is “encouraged by these early results,” keeping in mind that these patients have progressed after receiving a median of four prior therapies, and in some cases as many as 10, he said.

The focus now, he added, was combo studies “to further explore the potential of AMG 510 in lung and colorectal tumors” and perhaps hit other driving mutations within the disease.

Analysts at Jefferies said in a note to clients: "'High dose' data for colorectal cancer (CRC) shows 8% response rate (1/12 PR), and below our hopeful expectations for 15% ORR (double-digit is what investors generally like to see). Street's expectations were fairly low after the lung update weeks ago and since CRC is tougher than lung. AMGN has said however the bar is not high in 3L colorectal cancer. We learned today there were no additional responses in more pts beyond what was already known which could be somewhat disappointing in the short-term.”

On a call with investors, Jefferies also noted that: “(The company) comments suggest they're looking forward to some more monotherapy data in CRC and lung in early 2020 as next investor update. There are 10 more pts in each and more durability data will be helpful.”

They still see the upside in its potential for lung cancer being the biggest driver for the drug.

The much smaller biotech Mirati Therapeutics is also going after the same target with its MRTX849, which, with a little help from the Amgen buzz and a recent Novartis combo deal, has been generating its own noise of late. Data are expected from the company later this year.