Other analysts argued the market reaction was overdone. Alex Arfaei at BMO Capital Markets, in a research note Friday, said that "even in low PDL1 patients... Opdivo has a superior profile than the standard of care," and that it should still dominate the market.
The drug is part of a class known as checkpoint inhibitors that empower the immune system against cancer. Immunotherapy in general is a key focus at the conference, dominating headlines with drugs being developed by Merck, Roche, AstraZeneca and others in addition to Bristol-Myers.
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Bristol also presented several other datasets on Opdivo at the conference, including a combination study with its other immunotherapy drug, Yervoy. Opdivo's on the market for melanoma as well as another form of lung cancer, advanced squamous non-small cell lung cancer. Merck's Keytruda, in the same class, is on the market in melanoma.
Outside the immunotherapy world, Clovis Oncology, a smaller drug maker, had data on two medicines, rociletinib for lung cancer, and rucaparib, for ovarian cancer.
Cory Kasimov, an analyst with JPMorgan, described the company's showing at ASCO "controversial," calling the data a "mixed bag."
"Overall we are encouraged by the impressive response rates and duration of response seen so far with rucaparib, and think that it compares favorably to the data we have seen from other PARPs in ovarian cancer to date," Kasimov wrote in a Sunday research note, referring to the drug's mechanism of action. "Under normal circumstances, this update could get investors to take a much closer look at this candidate, but for now we expect ruca to still be overshadowed by roci."
Kasimov called Clovis' data on rociletinib "so-so," noting it showed the drug helped patients live eight months without their cancer progressing, down from 10.4 months previously reported, and short of the 13.5 months for a competing drug from AstraZeneca, known as AZD9291. Clovis' drug has a side effect of high blood sugar, which the company said could be managed with commonly used medicines.