A landmark decision for those battling melanoma.

Keytruda has been given rubber-stamp funding approval, after commercial negotiations between Pharmac and supplier Merck Sharp & Dohme wrapped up.

READ: Pharmac to fund melanoma drug Keytruda

The drug has prompted public petitions to Parliament, and Pharmac has been considering funding it since September last year.

Melanoma New Zealand Chief Executive Linda Flay said it's great news for melanoma patients.

Ms Flay said patients who are already taking Keytruda will be able to maintain their regime through a bridging programme by the drug company.

She said it's taken a considerable amount of time to get to this point, but they're thrilled that as of September 1st the drug will be publicly funded.

"It can never come too soon and we're just relieved that it's finally got through and patients now have options which they certainly haven't had in the past."

She said they now have two immunotherapy treatments in Keytruda and the earlier-funded Opdivo - which was given the funding tick by Pharmac in June.

Ms Flay said they will continue to advocate for the BRAF inhibitors to be funded for those who aren't suited to immunotherapy treatments.