Professor Georgina Long

Australian researchers says they have obtained ‘breakthrough’ results showing a new immune checkpoint inhibitor has proven effective in helping save the lives of advanced melanoma patients.

Melanoma Institute Australia Co-Medical Director, Professor Georgina Long will be presenting results of the RELATIVITY-047 trial of relatlimab in melanoma at the American Society of Clinical Oncology virtual meeting this week.

Relatlimab is the first immunotherapy treatment to target LAG-3, in contrast to other immune checkpoint inhibitors that target the CTLA-4 and PD-1 proteins.

In the RELATIVITY-047 study, 714 patients with previously untreated advanced melanoma were randomised to a fixed dose combination of relatlimab with nivolumab  or nivolumab monotherapy.

After a median follow up of 13.2 months, treatment with the relatinib combination doubled the progression free survival time compared to the use of nivolumab alone (10.1 vs 4.6 months respectively).

At one year, almost half of patients (47.7%) on the combination therapy had no disease progression, whereas nearly two-thirds of patients (64%) on the single therapy had progressed. Importantly, the combined therapy was also far less toxic to patients.

The incidence of grade 3/4 treatment-related adverse events was higher in the combination group (18.9%) versus nivolumab alone (9.7%).

“This is the first phase III study of a novel fixed dose combination to demonstrate a clinically meaningful benefit by dual inhibition of the LAG-3 and PD-1 pathways,” the trial investigators concluded

Professor Long said checkpoint inhibitors had been used in melanoma for several years and had proved most effective when used in combination. However this tended to increase their toxicity. Furthermore, about half of patients either did not respond or developed resistance to these treatments and therefore new treatments were still needed.

‘This drug [relatlimab ] gives us a third immune checkpoint inhibitor to add to the treatment toolkit which may be the difference between survival or not for melanoma patients around the world,” she said.

“Having a third immune checkpoint inhibitor means we can potentially make inroads in saving the 50% of advanced melanoma patients who don’t respond to current treatments.”