(Ands outside expert, analyst comment)
By Deena Beasley
CHICAGO, June 3 (Reuters) - Merck & Co's immunotherapy Keytruda improved survival as a stand-alone treatment for newly-diagnosed lung cancer patients and with chemotherapy for hard-to-treat squamous cell lung cancer, new data released on Sunday showed, further cementing the company's lead in the most lucrative oncology market.
Keytruda is competing with drugs from Roche, Bristol-Myers Squibb and others that also unleash the body’s immune system to attack tumors for dominance in lung cancer. They have racked up approvals for a variety of cancers, but newly-diagnosed lung cancer is seen as the biggest commercial opportunity.
The new results, presented at the American Society for Clinical Oncology (ASCO) meeting in Chicago, add to the view that Keytruda has "set the floor against which other therapies will need to be compared," Roy Baynes, head of clinical development at Merck, told Reuters.
One trial studied 1,274 patients with advanced non-small cell lung cancer (NSCLC) who tested positive for the PDL1 protein targeted by Keytruda to see if they could avoid chemotherapy.
Overall, Keytruda patients lived for a median of 16.7 months, compared with 12.1 months for patients on chemotherapy.
But patient outcomes were linked to the biomarker. Keytruda patients with PDL1 levels above 50 percent lived for a median of 20 months, compared with 12.2 months for chemotherapy.
"This is a true milestone for the field," said Dr. John Heymach, an ASCO expert from Houston's MD Anderson Cancer Center who was not involved in the trial. "The era in which chemotherapy is the only option for non-small cell lung cancer patients is drawing to a close."
Keytruda already has U.S. approval for use in combination with chemotherapy as an initial treatment for non-squamous NSCLC. It is also approved as a stand-alone treatment for lung cancer patients whose tumors have high PDL1 levels.
Merck said it is not yet clear whether Keytruda combined with chemotherapy is better than Keytruda alone in patients who express PDL1.
Since much of the benefit in the latest trial was seen in patients with high PDL1 levels, the opportunity for Keytruda alone for lung cancer "may be of less significance commercially," Evercore ISI analyst Umer Raffat said in a research note.
Severe side effects, including lung inflammation, occurred in 18 percent of Keytruda patients, compared with 41 percent of chemotherapy patients.
"Not only are patients living longer ... but they are also receiving a treatment that has substantially less toxicity," Dr. Heymach said.
For more ASCO coverage see: here
Researchers also presented results from a separate trial of Keytruda in patients with late-stage squamous cell NSCLC, which accounts for about 30 percent of lung cancer and is considered particularly difficult to treat.
The 559-patient trial found patients given Keytruda plus chemotherapy lived for a median of 15.9 months, compared with 11.3 months for chemotherapy alone.
Merck said Keytruda trial patients lived for a median of 6.4 months before their disease worsened, compared with 4.8 months for the chemotherapy-alone group.
In a trial presented at the meeting on Saturday, Roche's rival immune therapy, Tecentriq, combined with chemotherapy delayed progression of squamous NSCLC by 6.3 months compared with 5.6 months for a standard chemotherapy combination.
Survival results for the Roche trial were not yet available.
In its squamous lung cancer trial, Merck said serious side effects, including anemia and nausea, were seen in 69.8 percent on patients on Keytruda versus 68.2 percent for chemotherapy alone.
Reporting By Deena Beasley Editing by Robert Birsel and Bill Berkrot