Shares in Puma Biotechnology have rocketed after its investigational breast cancer drug neratinib, licensed from Pfizer, has hit its primary endpoint in a late-stage trial.

Neratinib improved disease-free survival by 33% compared with a placebo in a Phase III trial of 2,821 women with early-stage HER2-positive breast cancer. Participants had undergone surgery and adjuvant treatment with Roche’s Herceptin (trastuzumab) and Puma is now planning to file the tyrosine kinase inhibitor in the first half of 2015.

Alan Auerbach, Puma’s chief executive, said the trial is the first with a HER2 targeted agent that has shown a statistically significant benefit in the extended adjuvant setting, “which we believe provides a meaningful point of differentiation for neratinib”. He claimed that while Herceptin in the adjuvant setting has led to a reduction in disease recurrence in patients with early stage HER2-positive breast cancer, “there remains an unmet clinical need for further improvement in outcome in order to attempt to further reduce this risk of recurrence”.

Puma announced that it has amended its licensing deal with Pfizer, originally signed in October 2011, which makes the Los Angeles-based biotech responsible for clinical trial expenses, though it will pay lower royalties.

The change will result in an increase in R&D expenses of about $30 million and while the original royalty rate ranging between 10%-20%, this has now switched to fixed rate in the low- to mid-teens.

The news sent Puma stock soaring over 203% to $179 in after-hours trading to around, after closing at $58.98.