Pembrolizumab for metastatic adrenocortical carcinoma with high mutational burden: Two case reports

RATIONALE: In the setting of metastatic or locally advanced adrenocortical carcinoma, a limited number of therapies are available and their efficacy is generally below modest. The backbone of treatment remains surgery, even for metastatic disease, whenever it is possible, and mitotane. Chemotherapy can be used with limited results. A small subset of patients with adrenocortical carcinoma may have high mutational burden and harbor mutations in mismatch-repair genes. PATIENT CONCERNS: We report a 40-year old and a 28-year-old female patients with metastatic adrenocortical carcinoma refractory to multiple treatments. DIAGNOSIS: Next-generation sequencing detected high mutational burden (>10 mutations/megabase) in both patients, one of them with MSH2 mutation. INTERVENTIONS: They were treated with pembrolizumab (100 to 200 mg every 3 weeks). OUTCOMES: The patient harboring a MSH2 mutation experienced a long-term complete response after pembrolizumab, while the patient with high mutational burden and absence of mismatch repair deficiency did not have any response. LESSONS: To the best of our knowledge, this is the first report in the literature of a durable complete response after pembrolizumab in a patient with metastatic adrenocortical carcinoma. Differences in therapy sequencing, possibly abscopal effect related to multiple previous radiotherapy exposition, predictive values of high mutational burden and mutations in mismatch-repair genes are discussed.