Conference Coverage

Combo shows promise for checkpoint inhibitor-refractory urothelial carcinoma


 

REPORTING FROM SITC 2019

– Sitravatinib may “restore or enhance” the activity of anti-PD-1 therapy in patients with checkpoint inhibitor–refractory urothelial carcinoma, an investigator reported at the annual meeting of the Society for Immunotherapy of Cancer.

Dr. Pavlos Msaouel, University of Texas MD Anderson Cancer Center, Houston Jennifer Smith/MDedge News

Dr. Pavlos Msaouel

Clinical activity was observed with combination sitravatinib and nivolumab in patients with urothelial carcinoma who had disease progression on or after an immune checkpoint inhibitor and were previously treated with platinum-based chemotherapy.

“Up until a few years ago, the only therapies we had [for urothelial carcinoma] were cytotoxic, platinum-based chemotherapies,” said Pavlos Msaouel, MD, PhD, of the University of Texas MD Anderson Cancer Center, Houston.

“Thankfully, since 2016, immune checkpoint therapy has become part of our toolbox. But even with single-agent, approved immune checkpoint therapies, anti-PD-1/anti-PD-L1, the response rates are still low, around 20%, and durable responses are only seen in a subset of patients. So we have to do better, if possible, potentially by combining immune checkpoint therapies with other immunotherapies such as sitravatinib.”

Dr. Msaouel explained that sitravatinib inhibits a spectrum of related receptor tyrosine kinases, including TAM family receptors (TYRO3, Axl, and Mer), split family receptors (VEGFR2/PDGFR and c-KIT), and c-Met. Researchers are investigating sitravatinib in combination with nivolumab in a phase 2 trial of patients with urothelial carcinoma (NCT03606174). Dr. Msaouel presented results from one cohort on this trial – 33 patients who had previously received platinum-based chemotherapy and a PD-1/PD-L1 inhibitor.

At baseline, the patients’ median age was 68 years (range, 47-83 years), and 70% were male. Patients had metastatic (n = 30) or locally advanced (n = 3) disease. They had received a median of two (range, one to four) prior systemic therapies.

For this study, patients received oral sitravatinib at 120 mg daily and intravenous nivolumab at 240 mg every 2 weeks or 480 mg every 4 weeks on continuous 28-day cycles. Tumor assessments were performed every 8 weeks.

Results

Of the 22 patients evaluable for efficacy, 1 patient achieved a complete response, 5 had a partial response, 15 had stable disease, and 1 progressed. Eight patients had tumor regression greater than 30%.

Treatment duration exceeded 26 weeks in six patients. Nine patients, including four responders, were still on study at the data cutoff in mid-October.

“This ongoing trial continues to show promising clinical activity, including tumor regression and prolonged duration on treatment,” Dr. Msaouel said.

He added that combination sitravatinib and nivolumab has “an acceptable side effect profile, with manageable adverse events.”

Common treatment-related adverse events, in all 33 patients, were fatigue (58%), diarrhea (48%), decreased appetite (33%), dysphonia (33%), nausea (33%), and alanine aminotransferase increase (21%).

Grade 3 treatment-related adverse events included fatigue (12%), hypertension (12%), diarrhea (9%), lipase increase (9%), decreased appetite (3%), and palmar-plantar erythrodysesthesia syndrome (3%). There were no grade 4 or 5 treatment-related events.

Mirati Therapeutics sponsored the trial. Dr. Msaouel disclosed relationships with Mirati, Bristol-Myers Squibb, Exelixis, Pfizer, and Takeda.

SOURCE: Msaouel P et al. SITC 2019. Abstract O23.

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