Merck & Co’s cancer drug candidate vintafolide has improved on standard treatment for women with ovarian cancer, according to newly-published phase II data.
The PRECEDENT study – which appears in the Journal of Clinical Oncology – found that the combination of vintafolide with pegylated liposomal doxorubicin (PLD) was significantly better than PLD alone in patients with folate receptor-positive, platinum-resistant ovarian cancer.
The news is a boost to the drug’s prospects after the release of phase II data last week in non-small cell lung cancer (NSCLC), which showed the drug was unlikely to be superior to docetaxel alone, caused a massive reduction in the shares of Endocyte, the US firm which originally developed it.
Vintafolide was licensed by Merck from Endocyte in a deal valued at up to $1bn, provided the drug is approved for a total of six potential cancer indications, with analysts suggesting at the time that it could potentially achieve peak sales in excess of $2.5bn.
PRECEDENT showed that compared to PLD alone, the combination increased progression-free survival by 2.3 months to 5.0 months. In patients shown to have folate-positive tumours – using an investigational folate receptor-targeted companion diagnostic imaging agent called etarfolatide – the effect on PFS was even greater, at 5.5 months versus 1.5 months for PLD alone.
The publication of the results bodes well for early availability of vintafolide, which is currently under regulatory review in the EU based on the results of the phase II trial, while Merck (known as MSD outside the US) completes a pivotal trial called PROCEED.
Along with Merck, Endocyte has been “building up our commercial capabilities to prepare for a potential near-term EU launch”, according to Endocyte chief executive Ron Ellis.
Meanwhile, analysts have questioned the impact on Endocyte’s shares of the NSCLC study, pointing out that the trial was not statistically powered to show superiority to vintafolide to docetaxel unless the PFS difference between the drugs was at least 50 per cent.
Vintafolide is a small molecule drug conjugate (SMDC) that combines folate with the cytotoxic agent vinblastine. The drug is designed to deliver the payload directly to cancer cells by targeting folate receptors, which are expressed on 80 to 90 per cent of ovarian and lung cancers but not on most normal cells.