Outcomes of patients with unresectable or metastatic melanoma after cessation of immunotherapy following complete metabolic response or toxicities

BACKGROUND: Checkpoint inhibitors (CPIs) have changed the treatment paradigm for patients with advanced melanoma, with significant improvement in overall survival. This study evaluated the outcomes of patients with advanced melanoma who were treated with CPI and had cessation of treatment due to either complete metabolic response (CMR) or toxicities. AIMS: To assess the outcomes of patients with advanced melanoma who ceased immunotherapy due to either CMR or toxicities. METHODS: A retrospective study of patients with unresectable stage III or IV melanoma who were treated by a single prescriber across two tertiary centres in Queensland. Patients were identified from hospital medical records and the chemotherapy prescribing programme. Data collected were analysed, and progression-free survival (PFS) was evaluated. RESULTS: A total of 235 patients who ceased CPI due to either CMR or toxicities were included in this analysis. Of these, 182 patients (77.4%) ceased CPI due to CMR and 53 patients (22.6%) stopped due to treatment-related toxicities. At median follow-up of 48 months, the PFS was significantly longer in patients who ceased CPI following CMR compared to treatment-related toxicities (P = 0.0246). The 24-month PFS and 48-month PFS for patients who ceased CPI for CMR and toxicities were 87.6% versus 76.9% and 78.8% versus 62.8%, respectively, and 60.5% of patients had further response to therapy with rechallenged CPI upon progression. CONCLUSIONS: Durability of responses is demonstrated in patients who ceased CPI due to either CMR or toxicities. In patients with disease recurrence, further response to CPI is possible. The option to discontinue CPI should be discussed with patients following CMR.