OBJECTIVES: To understand the prescribing patterns of PD-1 inhibitors within an advanced melanoma population; guidelines do suggest anti-PD-1 therapies as a 1^st line treatment option dependent on BRAF-mutation, however PD-L1 testing is not considered powerful enough to exclude patients from anti PD-1 therapy. This analysis was conducted to understand the testing of PD-1 and usage of PD-1 inhibitors in an advanced melanoma population.

METHODS: Real-world data were collected through a point in time survey administered to physicians and patients in France, Germany, Italy, Spain and the UK (EU5) from December 2017 to March 2018. 231 physicians provided data for 1,913 advanced melanoma patients.

RESULTS: The mean age of the population was 59.5 years, 25% (n=472) of patients were in full time employment with 53% (n=1,019) male.st line therapy. Of these patients, 20% (n=154) were BRAF positive, 65% (n=503) were BRAF negative, 15% (n=119) were not tested/inconclusive. The usage of PD-1 inhibitors increased at 2^nd line treatment across all patient groups.

Of the patients receiving a PD-1 inhibitor at 1^st line, 32% (n=250) were tested for their PD-1 status, of those tested physicians classified 73% (n=182) as PD-1 positive, 18% (n=44) as PD-1 negative with the remaining 9% (n=24) currently unknown. Where known, the mean level of PD-1 expression in the physician classified PD-1 positive cohort was 39% (range 1%-100%); in the PD-1 negative cohort 3% (range 0-20%).

CONCLUSIONS: Physician prescribing of PD-1 inhibitors does not appear limited to patients who have been PD-1 tested or patients considered by the physician to present a positive result. The interpretation of PD-1 levels into ‘positive’ and ‘negative’ status differs notably based on physician subjectivity.