Pfizer has suffered a clinical setback with the news that a late-stage trial of its oncology blockbuster Sutent as a potential treatment for liver cancer has been halted over safety concerns.

The New York-based giant has discontinued the SUN 1170 Phase III study of Sutent (sunitinib) in advanced hepatocellular carcinoma following a review by an independent data monitoring committee. It has been halted because of a higher incidence of serious adverse events in the sunitinib arm of the trial compared to Bayer/Onyx’ Nexavar (sorafenib).

Furthermore, Sutent “did not meet the criteria to demonstrate that it was either superior or non-inferior to sorafenib in the survival of patients with advanced hepatocellular cancer”, Pfizer noted. Mace Rothenberg, head of clinical development for the company’s oncology unit, said there is “a great need for effective new therapies for patients with advanced liver cancer” and “the disappointing outcome of this trial challenges all of us to work harder to understand the complex biology of this disease”.

Sutent is already approved to treat advanced kidney cancer and gastrointestinal stromal tumors following disease progression and Dr Rothenberg said this latest trial “does not diminish our confidence” in the drug for those indications. He added that Pfizer will continue to study the potential role of Sutent “in the treatment of various types of cancer in late-stage trials”.

These include advanced non-small cell lung cancer, advanced castration-resistant prostate cancer and as an adjuvant treatment in kidney cancer. Other attempts to expand the label on Sutent have not proved successful and Phase III studies looking at the potential of the treatment for advanced breast cancer were halted last month.

Malaria treatment for pregnant women
Meantime, Pfizer has signed an agreement with Medicines for Malaria Venture (MMV) to develop a fixed-dose combination preventative treatment for pregnant women consisting of azithromycin and chloroquine. The World Health Organisation estimates that some 30 million pregnant women are at risk for malaria in endemic areas in Africa each year.

Pfizer and MMV will work with the London School of Hygiene and Tropical Medicine to coordinate Phase III trials and an independent committee of malaria experts will oversee them. The studies are expected to begin in Africa this summer with up to 5,000 participants.