The results of a Phase II clinical trial presented at the 2016 American Society of Clinical Oncology (ASCO) Annual Meeting show that advanced bladder patients treated with anti-PD-L1 immunotherapy atezolizumab displayed reduced tumor size and an increased median survival rate relative to survival rates of patients treated with carboplatin-based chemotherapy.
Approximately 450,000 cases of bladder cancer were diagnosed worldwide in 2012, with 77,000 people expected to be diagnosed in the United States this year. The standard form of treatment for advanced bladder cancer is cisplatin-based chemotherapy, with patients receiving the treatment showing median survival rates of 12–15 months.
However, approximately half of patients with advanced bladder cancer will not be considered for this option due to the risks involved with their advanced age or ongoing medical conditions. These patients, who receive carboplatin-based chemotherapy as a result, show a reduced median survival rate of 9–10 months.
This trail was a single-arm Phase II study of atezolizumab in patients with local or metastatic advanced urothelial cancer – the most common form bladder cancer in the United States. Named IMvigor210, the study included two groups of patients: those that received atezolizumab as a second-line therapy and those that received the drug as upfront treatment.
After a median follow-up of 14.4 months, 24% of patients responded to the treatment, with the longest duration of response being > 18 months. The median overall survival rate was 14.8 months.
Overall, 10–15% of patients displayed severe adverse effects on atezolzimab; the most common including rash, diarrhea, hypothyroidism and liver function abnormalities. Lead investigator on the trial Arjun Vasant Balar (New York University Langone Medical Center, NY, USA) commented; “The majority of our patients had few or no side effects from atezolizumab and only 6% of patients discontinued treatment because of toxicity. This is in stark contrast to the approximate 20% rate of treatment discontinuation from toxicity observed with carboplatin-based chemotherapy regimens. Immunotherapy appears to be much easier to tolerate than chemotherapy, and this is especially important for elderly patients”.
IMvigor20 is the first trial to test the efficacy of atezolizumab immunotherapy as an initial treatment for advanced bladder cancer. These encouraging results have lead researchers to plan a randomized Phase III trial of the drug as an upfront treatment for the disease.
“Up to half of patients with advanced bladder cancer are too frail to receive the only known survival-prolonging treatment, cisplatin. There is really no standard treatment for such patients,” continued Balar; “We are encouraged to see that atezolizumab immunotherapy may help address this major unmet need.”