Bayer and Onyx Pharmaceuticals have suffered a slight setback with the news that the second of four studies evaluating Nexavar as a treatment for breast cancer did not meet its primary endpoint of progression-free survival.

The 237-patient Phase II study, sponsored by Northwestern University, evaluated Nexavar (sorafenib) or placebo in combination with the chemotherapy paclitaxel in people with locally advanced or metastatic HER-2 negative breast cancer. The findings revealed that the combo showed a “positive trend” towards PFS but the results were not statistically significant.

Dimitris Voliotis, vice president, global clinical development oncology at Bayer HealthCare, said that the preliminary results “demonstrate a clinical signal in favour of this treatment combination”. He added that the data “require further analysis and interpretation before we determine the appropriate path forward”. Northwestern University’s William Gradishar, lead scientist on the trial, argued that “these encouraging data warrant further investigation”.

The results come just a week after Bayer and Onyx presented results at the joint European Cancer Organisation/European Society of Medical Oncology (ECCO-ESMO) meeting in Berlin showing that Nexavar extended PFS by 6.4 months when combined with Roche’s Xeloda (capecitabine), compared with 4.1 months for the latter chemotherapy alone.

The two other studies that the companies are running will evaluate Nexavar plus gemcitabine or capecitabine in the first- or second-line setting following progression on Roche’s Avastin (bevacizumab), and sorafenib plus docetaxel and/or Novartis’ Femara (letrozole) in the first-line setting.

Nexavar, which is approved for liver as well as advanced kidney cancer, is already a big earner and had second-quarter sales of 147 million euros, up 36.1%.