Duration of Anti-PD-1 Therapy in Metastatic Melanoma (STOP-GAP)

• Drug: Intermittent PD-1 inhibitor therapy
• Drug: Continuous PD-1 inhibitor therapy

Inclusion Criteria:

• Histologically confirmed melanoma that is unresectable / metastatic (stage III or stage IV).
• Eligible to receive treatment with a government approved and publically-funded PD-1 inhibitor, according to the guidance / indications described in the Product Monograph / Provincial Formulary.
• Patients must have evidence of unresectable / metastatic disease, that is considered evaluable by the investigator and can be followed, but measurable disease is not mandatory.
• Patients with brain metastases are allowed, provided they are stable according to the following definitions:
  1. Without evidence of progression for at least four weeks prior to randomization and have no evidence of new or enlarging brain metastases.
  2. Treated with surgerytreatment involving removal of cancerous tissue and/or tumours and a margin of healthy tissue around it to reduce recurrence and without evidence of progression prior to randomization and have no evidence of new or enlarging brain metastases.
  3. Treated with stereotactic radiosurgery and without evidence of progression prior to randomization and have no evidence of new or enlarging brain metastases.
• Patient is able (i.e. sufficiently fluent) and willing to complete the quality of lifethe overall well-being of a person diagnosed with cancer, encompassing both physical and emotional aspects of health and health utility questionnaires in either English or French. The baseline assessment must be completed within required timelines, prior to randomization. Inability (lack of comprehension in English or French, or other equivalent reason such as cognitive issues or lack of competency) to complete the questionnaires will not make the patient ineligible for the study. However, ability but unwillingness to complete the questionnaires will make the patient ineligible.
• Patient consent must be appropriately obtained in accordance with applicable local and regulatory requirements. Each patient must sign a consent form prior to enrollment in the trial to document their willingness to participate.
• Patients must be accessible for treatment and follow-up. Investigators must assure themselves the patients randomized on this trial will be available for complete documentation of the treatment, adverse events, and follow-up.
• Patients must be randomized prior to the start of, or within 16 weeks from, the initiation of PD-1 inhibitor treatment. For patients who are being randomized before the start of treatment, the PD-1 inhibitor should be started within 5 working days after randomization. Patients who initiate treatment with combination anti-PD-1 and anti-CTLA-4 therapies who experience toxicity may be randomized at the time prior to starting single-agent PD-1 inhibitor. Repeat imagingtests that create detailed images of areas inside the body must be done within 50 days prior to randomization to ensure the patient has no evidence of disease progression.