Background and Importance Only one phase III trial of enzalutamide with or without atezolizumab in men with metastatic prostate cancer who progressed on abiraterone has been reported in the literature. No cases have been reported in clinical practice with experience in the management of patients with lung and prostate cancer under concomitant treatment with atezolizumab and enzalutamide.

Aim and Objectives To describe the efficacy, safety and adherence of concomitant treatment with enzalutamide for metastatic castration-resistant prostate cancer and atezolizumab for metastatic lung adenocarcinoma in a patient case.

Material and Methods This was a descriptive, retrospective clinical case. The data (diagnostic tests, therapy and clinical course) were obtained by review of electronic medical records. Adherence was evaluate using medication possession ratio (MPR).

Results A 72-year-old male patient with stage IV non-small-cell lung cancer, negative eGFR, ALK and PD-L1, diagnosed in January 2019, received a first line standard chemotherapy. In September 2019, there was evidence of tumour progression and treatment with atezolizumab was started. In December 2019, patient was diagnosis of prostate adenocarcinoma with possible ganglionic involvement, surgery was performed and anti-androgen treatment was started. The patient continues maintenance treatment with atezolizumab and in December 2021, bone metastases of prostate origin were detected. Enzalutamide treatment is proposed for prostate cancer and maintenance atezolizumab for lung cancer. No cases have been reported in the literature, but there is one phase III trial, Imbassador250, which at least reports concomitant administration of the two drugs for prostate cancer. Given the favourable safety data from the study, and the efficacy data reported for both treatments for their corresponding indications, enzalutamide is initiated while treatment with atezolizumab is maintained. No toxicity from the treatments has been reported. The patient has maintained both treatments to the present day, maintaining clinical response for both tumours. The patient has shown 100% adherence to oral and intravenous treatment.

Conclusion and Relevance This is the first case report with evidence of efficacy of concomitant treatment with atezolizumab for lung cancer and enzalutamide for prostate cancer, with no additional toxicity. It is important to report these cases in real clinical practice because these conditions will not be present in clinical trials.

Conflict of Interest No conflict of interest