At the 101st American Association for Cancer Research (AACR) Annual Meeting in Washington, DC, in April, Pfizer presented a broad overview of its current oncology pipeline. This includes investigating new indications for approved drugs like sunitinib (Sutent) and novel agents like axitinib and crizotinib. Pfizer said it has 31 oncology drugs in the pipeline, and Jamie Christensen, MD, director of Translational Research at the company, said he expects several to come to market in the next 3 to 5 years.
Sunitinib Being Explored in Other Cancers
A day after the close of the AACR meeting, Pfizer announced that it was discontinuing the SUN 1170 phase III open-label study of sunitinib malate (Sutent) in advanced hepatocellular carcinoma (HCC). The trial was discontinued after a review by the independent Data Safety Monitoring Board (DSMB) confirmed “a higher incidence of serious adverse events in the sunitinib arm compared to the sorafenib [Nexavar] arm,” Pfizer said in a press release. In addition, the committee said sunitinib demonstrated neither superiority nor noninferiority to sorafenib in patients with advanced HCC. Sorafenib, manufactured by Onyx Pharmaceuticals and Bayer, is currently the only oral treatment known to extend life for people with HCC.
“The disappointing outcome of this trial challenges all of us to work harder to understand the complex biology of this disease,” said Mace Rothenberg, MD, senior vice president of Clinical Development and Medical Affairs for Pfizer’s Oncology Business Unit, in a statement issued by the company. Despite this setback for sunitinib in HCC, Pfizer views the drug as one of its most promising.
The FDA has already approved sunitinib as a treatment for metastatic renal cell carcinoma (RCC) and in gastrointestinal stromal tumors (GISTs) that are refractory to imatinib mesylate (Gleevec) or in patients with GIST who demonstrate intolerance to imatinib. “The result of this trial in HCC patients does not diminish our confidence in Sutent for the treatment of patients with RCC and GIST,” Rothenberg said.
Sunitinib, a tyrosine kinase inhibitor, works by blocking multiple molecular targets implicated in the growth, proliferation, and spread of cancer cells. Two important targets of sunitinib—vascular endothelial growth factor receptor (VEGFR) and platelet-derived growth factor receptor (PDGFR)—are angiogenic cytokines thought to play important roles in the development and progression of several tumors. Christensen said Pfizer plans to continue exploring applications for sunitinib in other cancers. “We’ve hit a few recent bumps in the road,” he said, “but we are taking these as learning experiences.” Sunitinib is being investigated in non–small cell lung cancer (NSCLC), advanced castration-resistant prostate cancer, and as an adjuvant therapy in RCC. Data from an ongoing trial of sunitinib in NSCLC are expected later this year.
New Targets Lead to New Agents
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