Pfizer has suffered a couple of late-stage clinical setbacks with the news that its oncology blockbuster Sutent has failed in two trials for breast cancer while another study of figitumumab.for lung cancer has been stopped.

The Phase III studies of Sutent (sunitinib) in advanced breast cancer, tested in combination with common chemotherapies, have not met their primary endpoints. The SUN 1064 study looked at sunitinib with docetaxel for the first-line treatment of patients with advanced HER-2 negative breast cancer but did not show a statistically significant improvement in progression-free survival compared to the chemo alone.
Similarly, the SUN 1099 trial of Sutent plus capecitabine, in previously-treated advanced breast cancer patients failed to show significant improvements in PFS compared with capecitabine alone.

Mace Rothenberg, senior vice president of clinical development and medical affairs at Pfizer’s oncology unit, said the drug “has been thoroughly evaluated in advanced HER-2 negative breast cancer, and while we are disappointed in the results, these trials have helped us define the limits and opportunities for the compound and better understand the complex biology of this disease”. He added that the firm is still “committed to the rigorous evaluation of investigational therapies in breast cancer, which despite recent advancements, continues to claim far too many lives each year”.

Sutent is currently approved for advanced kidney cancer and gastrointestinal stromal tumour, a cancer of the digestive system after disease progression on or for patients who are intolerant to Novartis’ Glivec (imatinib). It is a big earner, fourth-quarter sales reached $293 million, up 33%, and it is being studied for other solid tumors including advanced non-small cell lung, castration-resistant prostate and advanced liver cancers.

Meantime Pfizer announced that it is discontinuing another Phase III trial of figitumumab in combination with erlotinib (Roche’s Tarceva) as a second/third-line treatment in patients with previously-treated advanced non-adenocarcinoma NSCLC. The decision was taken after an independent data safety monitoring committee said the combo is unlikely to demonstrate a statistically significant improvement in overall survival compared to erlotinib alone in the study population.

In December, Pfizer pulled a trial of figitumumab as a first-line therapy when the DSMC said that the addition of the drug to paclitaxel plus carboplatin would be unlikely to meet the primary endpoint of improving overall survival. Of the latest disappointment, Dr Rothenberg said that Pfizer is working “to thoroughly analyse all available data from the figitumumab programme to better understand the compound and the IGF-1R (insulin growth factor-1 receptor) pathway”.

He added that as “a pioneer in the IGF-1R field, we are committed to a thorough evaluation of figitumumab” and Pfizer will “carefully review our extensive clinical database” to identify the “right patient population in which to evaluate this compound”. Figitumumab is still being studied as a possible treatment for prostate, breast and lung cancers and for Ewing’s sarcoma.