Australian anti-PD-1 therapy to treat advanced melanoma

Healthcare company MSD has announced that its anti-PD1 immunotherapy pembrolizumab (trade name KEYTRUDA) has been registered by the Therapeutic Goods Administration (TGA) as monotherapy for the treatment of advanced melanoma. The prescription-only medicine is the first anti-PD-1 (programmed cell death protein 1) immunotherapy to obtain TGA approval in Australia.

The announcement follows a worldwide study, published in The New England Journal of Medicine, which compared pembrolizumab to the immune checkpoint inhibitor ipilimumab (trade name YERVOY), one of the standard treatments for advanced melanoma patients. Australian clinicians were actively involved in the clinical trial program, with one of the highest recruiting centres being Melanoma Institute Australia (MIA).

Pembrolizumab is a humanised monoclonal antibody that reactivates the immune system to attack melanoma cells by inhibiting the PD-1 immune checkpoint on immune T cells - which, if left unchecked, allows cancer cells to pass undetected by the body’s natural defences. Professor Richard Kefford AM, the co-director of research at MIA, said the medicine “bolsters the immunotherapy options available to treat melanoma that has spread to other skin sites, the lymph nodes or organs”.

The latest findings show that pembrolizumab reduces the size of the tumours in patients with advanced melanoma in approximately 70% of patients, with deep reduction in over 30%. Patients using the drug recorded a one-year survival rate of 74%, while those who received ipilimumab had a survival rate of 58%.

“The tumour shrinkage seen with pembrolizumab is impressive,” said MIA oncologist Associate Professor Georgina Long. She claimed the new findings are “the final piece of data that show the anti-PD-1 antibody pembrolizumab is better than current treatments for patients with advanced melanoma”.

According to Professor Kefford, the breakthrough is “probably the most important development in the treatment of this disease ever, and a landmark in terms of cancer treatment in general”. Associate Professor Long added that the new drug is currently being considered for a Pharmaceutical Benefits Scheme (PBS) listing - “which would enable access for all Australians with metastatic melanoma” - and its activity in other cancers is under investigation.

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