Initial excitement with PD-1 inhibitors was focused on renal cell carcinoma, lung cancer, and melanoma. However, a second wave of excitement has been generated by this approach in bladder cancer, explains Brian I. Rini, MD.

Promising data from a phase I trial exploring the anti-PD-L1 therapy MPDL3280A were presented at the 2014 ASCO Annual Meeting, explains Rini. This study explored treatment with MPDL3280A in 67 patients with metastatic urothelial bladder cancer who received prior chemotherapy.

The objective response rate with MPDL3280A was 43% in PD-L1 positive patients (IHC 2/3). At the time of the data cut-off, 94% of patients had ongoing responses. This response rate is as high as chemotherapy with a promising safety profile, representing a potential "game-changer," Rini explains.

The current standard in bladder cancer is gemcitabine plus cisplatin for most patients. Adding to this, it makes sense to combine chemotherapy with a PD-1/PD-L1 targeted agent for patients with bladder cancer, Rini believes. Additionally, for patients who are unfit for chemotherapy, the level of activity as a single-agent is particularly promising, Rini notes.