Tumor tests for immuno-oncology drugs need some work, cancer experts say

Drugmakers are quick to cite results from tests for new immuno-oncology meds, with companies such as Bristol-Myers Squibb ($BMY), Merck ($MRK), Roche ($RHHBY) and Pfizer ($PFE) screening for biomarkers in tumors to see which individuals would benefit from the drugs. But the tests are not always reliable and could leave out a subset of patients who are a good fit for the drugs, according to researchers.

Using protein levels in a tumor to guide treatment decisions is not as effective as looking at genes, cancer experts told Reuters. Drugmakers don't all follow the same standards when developing tests for meds, and results can vary depending on which part of the tumor was biopsied and how much the cancer has spread. And while clinical trials for PD-1 blockers Opdivo from BMS and Keytruda from Merck show the drugs work best in patients who test positive for PD-L1, a related protein, some patients who tested negative still benefited from therapy.

BMS recently unveiled new data for Opdivo, showing that combining the drug with cancer-fighter Yervoy was more effective in treating advanced melanoma than Yervoy alone. But patients who didn't have PD-L1 detected in their tumors but still received the combo drug lived more than twice as long without their disease worsening.

Yale Cancer Center's Dr. Roy Herbst

"We shouldn't withhold immunotherapy from patients based on a biomarker yet," said Dr. Roy Herbst, chief of medical oncology at Yale Cancer Center, about Opdivo (as quoted by Reuters). "We don't even know if PD-L1 is the right biomarker."

Developing more accurate tests for the meds could help drugmakers as they look to cash in on a rapidly growing field. The PD-1 market could generate sales of $22 billion to $33 billion by 2022, analyst say, and companies such as Merck and BMS are chasing new indications for their drugs to grab the PD-1/PD-L1 crown.

Meanwhile, drugmakers are turning to genetic testing as a viable way to evaluate cancer treatments, rather than relying solely on tumor testing. The National Cancer Institute is launching an oncology trial, striving to match 1,000 advanced cancer patients with drugs that can target tumors by their genetic mutations, The Wall Street Journal reports. Companies including Novartis ($NVS), Pfizer, AstraZeneca ($AZN), Verastem ($VSTM) and Boehringer will lend drugs to the initiative.

- read the Reuters article
- here's the WSJ story (sub. req.)
- get more from the NYT (sub. req.)

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