In patients with advanced or metastatic urothelial carcinoma (mUC), atezolizumab monotherapy is tolerable, safe, and effective over 3 years, according to researchers.
A team led by Daniel P. Petrylak, MD, of the Yale Cancer Center in New Haven, Connecticut, evaluated 95 patients (76% male; median age 66 years) from the US and Europe treated with atezolizumab, an immune checkpoint inhibitor of programmed death ligand 1 (PD-L1), in a long-term follow-up of a phase I trial. Patients with mUC received atezolizumab intravenously at 15 mg/kg or 1200 mg every 3 weeks. For 47% of patients, atezolizumab was third-line therapy or greater.
Over a median 37.8 months, 9% of patients experienced a grade 3 to 4 treatment-related adverse event during the first year of treatment, with no serious events occurring later. Just 1 patient stopped treatment due to a medication-related event. The most common side effects were fatigue, asthenia, decreased appetite, and pruritus.
More than a quarter (26%) of patients had an objective response that lasted a median 22.1 months. Median progression-free survival and overall survival rates were 2.7 months and 10.1 months, respectively. Twenty-seven percent of patients survived to 3 years.
All patients were pre-assessed for PD-L1 expression on tumor-infiltrating immune cells. By subgroup, response occurred in 40% and 11% of patients with PD-L1 expression of at least 5% tumor-infiltrating immune cells or less than 5%, respectively. These patients survived a median 14.6 months and 7.6 months, respectively.
“Collectively, clinical results reported here compare well with published results for other checkpoint inhibitors or chemotherapy and support a continuing role for atezolizumab in altering treatment paradigms and outcomes in patients with mUC,” Dr Petrylak and colleagues concluded in JAMA Oncology. They urged future studies of single-agent atezolizumab and combination therapies in a variety of settings.
This study was funded by F. Hoffmann–La Roche Ltd/Genentech, Inc., which supplied atezolizumab (Tecentriq).
Petrylak DP, Powles T, Bellmunt J, et al. Atezolizumab (MPDL3280A) monotherapy for patients with metastatic urothelial cancer long-term outcomes from a phase 1 study. JAMA Oncol. doi:10.1001/jamaoncol.2017.5440 [Published online February 8, 2018]