FDA fast-tracks Merck's cancer blockbuster-in-waiting

Merck KGaA's blockbuster candidate evofosfamide has been granted fast-track status from the US FDA for advanced pancreatic cancer.

Evofosfamide already has fast-track status in the US as a treatment for soft tissue sarcoma (STS) and – if approved by the FDA – could quickly generate sales in excess of $1 billion in each indication, according to analysts at Edison.

Merck and partner Threshold Pharmaceuticals are currently conducting phase III trials in both STS and pancreatic cancer that should generate survival data early next year, with follow-up indications in non-squamous non-small cell lung cancer (NSCLC), glioblastoma and multiple myeloma adding to the drug's future sales potential.

The FDA has awarded fast-track status to evofosfamide in combination with gemcitabine in pancreatic cancer and alongside doxorubicin.

Evofosfamide – also known as TH-302 – is an investigational hypoxia-activated prodrug which is activated under the low oxygen conditions found in tumours resulting from malignant tissue growth outstripping blood supply.

Low oxygen can cause resistance to traditional chemotherapy and radiotherapy, often leading to disease progression, so a major factor in evofosfamide's appeal is its broad utility in hard-to-treat solid tumours.

Merck licensed the drug from Threshold in 2012 in a $550 million agreement, including $110 million upfront, that will look like fantastic value if evofosfamide's sales potential is fulfilled.

'Evofosfamide is targeting multiple indications in markets with multi-billion dollar opportunities,' said Edison analysts Philippa Gardner, Maxim Jacobs and Mick Cooper in a recent research note.

The successful launch of Celgene's Abraxane (albumin bound paclitaxel) for pancreatic cancer and the failure of Ziopharm Oncology's competing drug candidate palifosfamide in STS have dented confidence in evofosfamide's prospects.

Moreover, evofosfamide failed to show an overall survival benefit in an open-label pancreatic cancer trial when the combination with gemcitabine was comparted to gemcitabine alone, but Edison notes this study was not statistically powered to show a mortality benefit.

'We believe concerns relating to these events may be misplaced,' stated the Edison analysts, who pointed out that the drug is one of the most advanced first-line STS candidates in a market with around $1.4 billion potential and limited competition.

Evofosfamide is just one cancer asset with significant potential in Merck's portfolio. The company is also developing MSB0010718C, a novel anti-PD-L1 antibody for various cancers, in collaboration with Pfizer.