Atezolizumab in Platinum-treated Locally Advanced or Metastatic Urothelial Carcinoma: Clinical Experience from an Expanded Access Study in the United States.

BACKGROUND

Atezolizumab (anti-programmed death-ligand 1) was approved in the USA, Europe, and elsewhere for treatment-naive and platinum-treated locally advanced/metastatic urothelial carcinoma (mUC).

OBJECTIVE

To report efficacy and safety from an atezolizumab expanded access study.

DESIGN, SETTING, AND PARTICIPANTS: This single-arm, open-label study enrolled 218 patients at 36 US sites. Key eligibility criteria included progression during/following ≥1 platinum-based chemotherapy for mUC or in perioperative setting (progression within 12 mo) and Eastern Cooperative Oncology Group performance status (ECOG PS) 0-2.

INTERVENTION

Patients received atezolizumab1200mg intravenously every 3 wk until loss of clinical benefit, unacceptable toxicity, consent withdrawal, decision to discontinue, death, atezolizumab commercial availability, or study closure.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Key end points reported herein included Response Evaluation Criteria in Solid Tumors v1.1 objective response rate and duration, disease control rate (DCR; response or stable disease), and safety.

RESULTS AND LIMITATIONS

All patients received prior systemic therapy (68% mUC; 27% adjuvant; and 26% neoadjuvant). At baseline, 57% of 214 treated patients had ECOG PS ≥1, 19% had hemoglobin <10g/dl, and 25% had liver metastases. Median treatment duration was 9 wk (interquartile range [IQR], 6-12 wk). Median follow-up duration was 2.3 mo (IQR, 1.6-3.4 mo) overall and 2.7 mo (IQR, 2.0-3.5 mo) in patients not known to have died. Seventeen of 114 evaluable patients (15%) had objective responses (16 ongoing at study termination). DCR was 49%. Treatment-related adverse events (mostly fatigue) occurred in 98 of 214 treated patients.

CONCLUSIONS

The benefit/risk profile of atezolizumab was consistent with that observed in previous studies, despite pretreatment and poor prognostic factors. These results suggest a potential role for atezolizumab in a broader patient range than typically eligible for phase 1-3 studies.

PATIENT SUMMARY

In this expanded access study, atezolizumab was active and tolerable in a range of patients with platinum-treated metastatic urothelial carcinoma.