Opdivoand and Yervoy help activate patients' immune systems to recognise and attack unresectable malignant mesothelioma, which cannot be treated surgically.

The medications will from July 1 be listed on the federal government's Pharmaceutical Benefits Scheme, reducing treatment to about $41.30 per script or $6.60 for patients with a concession card.

More than 700 patients will benefit from the listing annually.

Without the PBS subsidy, they could have paid more than $130,000 per treatment course.

About 800 Australians are diagnosed with inoperable malignant mesothelioma each year.

Exposure to asbestos is linked to more than 90 per cent of cases, with men more likely to be diagnosed due to workplace exposure.

The aggressive cancer can lay dormant for decades or take up to 60 years to develop.

This means diagnosis is often delayed and most patients present with advanced or inoperable disease.

Oncologist Keith Horwood says the PBS listing of the drugs is a significant milestone for Australians living with the devastating disease.

"Australia has one of the world's highest incidence rates of mesothelioma," he said.

"For survival rates to improve, patients must receive timely access to novel treatments, which is why as clinicians, we welcome the first reimbursed immunotherapy for mesothelioma."

Former butcher and retired construction worker, Alan, 75, was diagnosed with pleural mesothelioma in 2020 after experiencing persistent shortness of breath.

"The first thing I thought when they told me I had mesothelioma, was 'geez, that sounds like a country in Europe'," he said.

"I wasn't prepared for the devastating news that followed."

Alan traced the likely cause of his cancer back to the 1970s when he was exposed to asbestos during a renovation at his butcher shop

"We didn't know the dangers of asbestos, so it was in everything and was everywhere,' he said.

"I've had 75 good years, and I'm hoping with treatment, to get a few more, so I can spend it with my grandkids and watch them grow up."

Australian Associated Press