By Ben Hirschler
LONDON (Reuters) - Cancer doctors struggling to work out the best way to use modern immunotherapy drugs now have further evidence of the benefits of adding them to chemotherapy, despite earlier scepticism.
News that Roche's immune system-boosting drug Tecentriq delayed lung cancer progression when given alongside chemo and its older drug Avastin validates the approach for the first time in a large Phase III clinical trial.
It is a significant milestone for physicians, patients and investors, who are trying to assess the competitive landscape as drugmakers race to develop better ways to fight tumours in previously untreated lung cancer.
Lung cancer is by far the biggest oncology market and first-line treatment provides access to the most patients, opening up potential annual sales forecast by some analysts at $20 billion.
Roche and Merck & Co have led the way in pioneering so-called "chemo-combo" treatment, while AstraZeneca and Bristol-Myers are betting primarily on mixing two immunotherapies. AstraZeneca notably failed to show a similar benefit in a high-profile clinical trial in July.
Stefan Zimmermann, an oncologist at Lausanne University Hospital in Switzerland, said the Roche data would help scotch concerns that chemo might hamper the new class of immuno-oncology medicines.
"Many experts in the field will be relieved because there has been uncertainty ... I think this will really encourage many of us to use this combination upfront," he told Reuters.
"For now, the only positive data that we have is for chemo combination."
Merck, in fact, already has U.S. approval to add chemo to its immunotherapy drug Keytruda - but this was based on a small trial and the company withdrew a similar European application last month, knocking confidence in its strategy.
Since Keytruda, Bristol's Opdivo, Roche's Tecentriq and AstraZeneca's Imfinzi are all rival inhibitors of biological switches known as PD-1 or PD-L1, the market is "largely a zero-sum game", according to Bernstein analyst Tim Anderson.
"Roche's good fortune means there is less to go around for other companies," he said.
In the case of Merck, the U.S. drugmaker now faces a rival with a different and perhaps superior drug combination. Roche believes adding Avastin in addition to chemo can further help restore anti-cancer immunity.
For AstraZeneca and Bristol, the bar has just been raised for two other key clinical trials sponsored by the drugmakers that are expected to report results in 2018.
Roche itself will present full results on the ability of its new combination to delay the worsening of lung cancer at a European Society for Medical Oncology meeting in Geneva on Dec. 7. Data on whether it also helps patients live longer is expected in the first half of next year.
Overall survival is the gold standard in cancer care but proving a treatment extends the time before disease progresses is an important marker on the way.
"If there is positive progression-free survival then I think it is very, very likely this will also translate into an overall survival benefit over time," said Zimmermann.
(Reporting by Ben Hirschler; Editing by Mark Potter)