Keytruda, Merck’s blockbuster cancer treatment, dramatically improved survival rates for the most common type of lung cancer, according to data from the US pharmaceutical company, which is delving deeper into immunotherapy.

Dr Roy Baynes, chief medical officer at Merck, said ahead of the American Society of Clinical Oncology in Chicago this weekend that a “big change in outcomes” had been observed for patients with non-small cell lung cancer treated with Keytruda. The drug was first approved by US regulators five years ago to treat skin cancer.

Some 23.2 per cent of patients who had not received previous treatment survived after five years, a significant leap in life expectancy compared to the historical average of 5 per cent. If a patient had failed to respond to previous treatments, their survival rate was still much higher than before: 15.5 per cent after five years.

“It is a terrific time for cancer patients. Progress is rapid and I think it is informed,’ he said.

Keytruda has become a blockbuster drug for Merck, with US regulatory approval for 18 diseases and 11 tumour types. Sales soared 88 per cent to $7.2bn last year, helping the company’s stock record the best performance in the Dow in 2018.

The targeted therapy known as a checkpoint inhibitor enables a body’s own immune system to fight cancer. By blocking a PD-1, a protein on the surface of the immune system’s T-cells, the drug allows the cells to attack tumour cells.

The new study shows that patients who showed a high level of PD-1 responded to the drug at almost double the rate of those with lower levels.

Dr Monica Bertagnolli, president of Asco, said the study gives oncologists more information about how to target drugs. “One of the most important issues we are dealing with in immunotherapy right now is who is going to respond, versus who is not,” she said.

The lung cancer survival data comes after a separate study showed impressive results on the survival of patients with advanced melanoma.

That study, published last year, showed more than 40 per cent of patients with this kind of skin cancer who had not failed previous treatments survived for five years. Some 34 per cent of patients who had not responded to previous treatments survived for that length of time.

Dr Baynes said the company is shifting its focus to testing Keytruda in combination with other drugs — including other immunotherapies — in 400 studies.

Merck is also looking at other ways to bolster its oncology pipeline, including acquiring Peloton Therapeutics for up to $2.2bn last month. The biotech company boasts a promising possible drug for renal cell carcinoma, or kidney cancer, among other potential development candidates. Merck will pay $1.05bn in cash and Peloton shareholders will be eligible to receive a further $1.15bn if it hits regulatory and sales targets.

At the Chicago conference alone, Keytruda will feature in about 140 presentations. One late-stage phase-three trial focused on tough-to-treat gastric cancer showed thet Keytruda was as good as chemotherapy — but without the side effects.

Dr Richard Schilsky, chief medical officer at Asco, said this could lead to another change in the standard of care for patients with the disease. “It is clearly better than chemo,” he said.

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