Assessing the use of anti-PD1 monotherapy as adjuvant therapy and determinants of treatment choice in stage III cutaneous melanoma in the US.

BACKGROUND

The objective of this study was to describe real-world adjuvant therapy (AT) use by disease substage and assess determinants of treatment choice among patients with stage III melanoma.

METHODS

This non-interventional retrospective study included survey responses and data from patient records provided by US medical oncologists. Survey responses, patient demographic/clinical characteristics, treatment utilization, and reasons for treatment were reported descriptively. The association between patient and disease characteristics and AT selection was assessed using logistic and multinomial regression models, overall and stratified by AJCC8 substage (IIIA vs. IIIB/C/D) and type of AT received (anti-PD1 monotherapy, BRAF/MEK, no AT), respectively.

RESULTS

In total 152 medical oncologists completed the survey and reviewed the charts of 507 patients (168 stage IIIA; 339 stages IIIB/IIIC/IIID); 405 (79.9%) patients received AT (360/405 (88.9%) received anti-PD1 therapy; 45/405 (11.1%) received BRAF/MEK therapy). Physicians reported clinical guidelines (61.2%), treatment efficacy (37.5%), and ECOG performance status (31.6%) as drivers of AT prescription. Patient-level data confirmed that improving patient outcomes (79%) was the main reason for anti-PD1 prescription; expected limited treatment benefit (37%), patient refusal (36%), and toxicity concerns (30%) were reasons for not prescribing AT. In multivariable analyses stage IIIB/IIIC/IIID disease significantly increased the probability of receiving AT (odds ratio [OR] 1.74) and anti-PD1 therapy (OR 1.82); ECOG 2/3 and Medicaid/no insurance decreased the probability of AT receipt (OR 0.37 and 0.42, respectively) and anti-PD1 therapy (OR 0.41 and 0.42, respectively) among all patients and patients with stage IIIA disease.

CONCLUSION

Most patients were given AT with a vast majority treated with an anti-PD1 therapy. Physician- and patient-level evidence confirmed the impact of disease substage on AT use, with stage IIIA patients, patients without adequate insurance coverage, and worse ECOG status having a lower probability of receiving AT.