Mixed news for Sanofi's cancer drug Zaltrap

Sanofi and Regeneron's colorectal cancer drug Zaltrap has been given a six-month review period by the US FDA, setting it up for possible approval in early August.

Its development in prostate cancer has hit a hurdle, however, with Sanofi announcing disappointing results in a phase III trial.

Zaltrap (aflibercept) - also known as VEGF Trap - has been filed for approval in the US for use in combination with irinotecan-fluoropyrimidine-based chemotherapy in patients with metastatic colorectal cancer (mCRC) who have been previously treated with an oxaliplatin-containing regimen.

The US filing was based on the results of the phase III VELOUR trial, which compared Zaltrap to placebo on top of chemotherapy in 1,226 mCRC patients.

Data presented from the study last year showed that Zaltrap extended overall survival from 12.1 months for placebo to 13.5 months, while progression-free survival increased from 4.7 to 6.9 months.

Sanofi filed for approval of the drug as a second-line mCRC therapy in Europe towards the end of last year. Meantime, Regeneron and partner Bayer have already been granted US approval for aflibercept as a treatment for age-related macular degeneration under the Eylea brand name.

Market research firm Decision Resources has estimated that if Zaltrap is approved this year in the US and Europe for mCRC, it will achieve peak sales of $250m in the second-line setting, with potential blockbuster sales if it can also show efficacy as a first-line therapy.

If approved, Zaltrap will enter a second-line treatment category currently dominated by Roche and Chugai's Avastin (bevacizumab) with sales of more than $6.6bn last year.

Meanwhile, fast-track review means that it can also get a head start over another rival therapy - Eli Lilly's ramucirumab - which is currently in phase III trials and also tipped as a strong new entrant for mCRC.

On the downside, top-line results from a second phase III study in prostate cancer failed to show any improvement in overall survival with Zaltrap, a major blow as this was the considered a key indication for the drug.

The trial, called VENICE, compared first-line treatment with Zaltrap to a regimen of docetaxel and prednisone in patients with metastatic androgen-independent prostate cancer. It is the only other cancer indication for aflibercept in phase III, according to Sanofi's latest pipeline update.