Background: Immunotherapies like the cytotoxic T-lymphocyte antigen 4 inhibitor ipilimumab show durable clinical benefit in patients with advanced melanoma. Reliable prognostic markers and risk scores in the era of immunotherapy are still lacking.
Patients and methods: We collected characteristics and outcomes on 134 patients with metastatic melanoma treated with ipilimumab between 2011 and 2014 at a single centre. Cox regression including multivariable fractional polynomials was used to identify independent markers for overall survival (OS). Internal model validation was done using bootstrap procedures.
Results: After a median follow-up of 16.1 months the median OS was 7.1 months (95% confidence interval [CI], 6.5-9.8). Nineteen of 134 patients (14.2%) had tumour remissions, 16 partial and 3 complete; 75% had progressive disease. We identified three independent adverse factors for OS: elevated lactate dehydrogenase (LDH) (hazard ratio [HR] 1.03, 95% CI 1.02-1.04), Eastern Cooperative Oncology Group performance status >0 (HR 1.91, 95% CI 1.10-3.30), and number of organs involved (NOI) (HR 1.51, 95% CI 1.22-1.86). To build an easy-to-apply risk score, we dichotomized LDH (>upper limit of normal) and NOI (>2) to built 3 prognostic groups: favourable (no adverse factors, N = 17), intermediate (1 adverse factor, N = 38), and poor prognosis (≥2 adverse factors, N = 73). Respective 12 and 18-month OS for the risk groups were: 85% and 73% (favourable), 41% and 29% (intermediate), and 12% and 6% (poor) (p < 0.001).
Conclusion: We propose a simple prognostic score for survival in patients with advanced melanoma treated with ipilimumab using readily available clinical parameters.
Keywords: Ipilimumab; Metastatic Melanoma; Prognostic Score; Risk Factors.
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