Shares in Genmab have taken a bashing after the company said that a late-stage trial of zalutumumab in head and neck cancer failed to meet its main goal.

The Danish company has announced top-line results from a zalutumumab Phase III study in patients with recurrent or metastatic squamous cell carcinoma of the head and neck who failed standard platinum-based chemotherapy. Median overall survival for patients on the Genmab antibody in combination with best supportive care was 6.7 months on average, compared to 5.2 months for BSC alone.

The Copenhagen-based group noted that although this represented a 30% improvement, the result was “not sufficient to demonstrate a statistically significant difference in overall survival, the primary endpoint of the study”. However, patients on zalutumumab did experience a 61% increase in progression free survival compared to the BSC alone arm, adding that 28% of patients randomised to the latter (95 people) and 14% in the zalutumumab arm (191) “received other anti-cancer therapies not permitted by the protocol”.

The compound was generally well tolerated but adverse events reported more frequently for patients in the zalutumumab plus BSC group were infusion related reactions, skin and nail disorders, electrolyte disturbances, gastrointestinal and eye disorders, as well as infections and headache.

Genmab is pretty upbeat and chief executive Lisa Drakeman said the progression free survival data "indicates that zalutumumab can provide a benefit to these cancer patients”. She added that the company will review “with our clinical advisors and the regulatory agencies how to best proceed with this product”.

While the company has not given up on zalutumumab, which targets the epidermal growth factor receptor, investors are worried. Genmab shares fell 20.4% to close at 73.50 Danish kroner.