Nektar Therapeutics has seen its share price devastated after revealing disappointing trial data for its candidate NKTR-214 in combination with Bristol Myers-Squibb’s Opdivo at the American Society of Clinical Oncology (ASCO) annual event in Chicago.

According to the data, the drug combo performed much less effectively than anticipated in the treatment of melanoma and kidney cancer based on previous, promising studies, sending Nektar’s stock crashing by a massive 41.8%, carving the company’s value from $15 billion to $9 billion. According to research from Bloomberg, it was the biggest one-day loss by an S&P 500 Index company in over five years, and the worst ever for Nektar itself.

"You have to think of it as a snapshot, it's a moment in time," commented Nektar Chief Scientific Officer Johnathan Zalevsky at the event following the reveal of the data. "We have high confidence based on our data that, over time, these response rates are going to improve."

To this end and in spite of the poor demonstration of the candidate’s efficacy, both companies plan to push on with Phase 3 trials of the drug. BMS is currently pursuing a partnership with Nektar, signed earlier this year, which aims to develop NKTR-214 across 20 indications and nine tumour types. The pharma giant only saw its stock dented on the news of the candidate’s underwhelming performance, dropping by around 3%.

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