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CHICAGO — For years, scientists said creating a drug around the KRAS protein was impossible. On Monday, Amgen (AMGN) showed it had developed a medicine that shrank tumors in 50% of lung cancer patients.

These lung cancer patients — just 10 of them because this is an early-stage clinical trial — all had tumors that tested positive for a particular mutation in KRAS, a cell-signaling protein. The 50% response rate to AMG 510 is an improvement over the 30% response rate first reported by Amgen last month. It also exceeds investor expectations.


Scientists have long known that KRAS mutations cause cancer, but discovering drugs capable of blocking KRAS has proven difficult. The protein is spherical and nearly featureless — its structure has been compared to a tennis ball — leaving potential drugs with few, if any, effective attachment points.

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  • “The results: Five out of 10 evaluable lung cancer patients had partial responses; another four had stable disease. All five of the responders remain on AMG 510 with treatment durations ranging from seven weeks to seven months.”
    I found this sentence quite confusing and unclear: what does exactly “evaluable” stay for? You wrote “5 out of 10 had partial response, another 4 had stable disease” does it mean they did not responded? it did not progress?

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