Puma gains as Roche breast cancer combo disappoints

Few would have predicted that little biotech Puma would get the advantage over mighty Roche in the race to develop a new breast cancer drug.

But that’s what has happened at this year’s ASCO, as Roche’s expensive combination of Perjeta (pertuzumab), Herceptin (trastuzumab) and chemotherapy in adjuvant breast cancer produced disappointing results.

Ostensibly the APHINITY trial was a success, reducing risk of breast cancer recurrence or death by 19% in HER-2 positive early breast cancer compared with Herceptin and chemo standard care.

But the trial met its primary endpoint by the smallest of margins, raising concerns about how regulators will regard the drug.

At three years, 94.1% of the women treated with the Perjeta-based regimen did not have their breast cancer return compared to 93.2% treated with Herceptin and chemotherapy.

Thomas Shrader, an analyst at Stifel, told Street Insider that the APHINITY trial "seems unattractive," opening up an opportunity for Puma's drug.

"It will be interesting to see payer responses in the new world. As expected, the treatment effect was lower in HR+ women than in HR- women. We await the full data before changing our model, but both the overall effect seen in APHINITY and the HR+ treatment imbalance seem to leave plenty of room for neratinib to have a significant spot in the extended adjuvant treatment landscape," he concluded.

Roche’s share price fell 4.27% following the announcement – a significant drop for a company of this size, while Puma’s shares climbed over the course of the conference amid speculation over the results.

Neratinib is likely to be approved by the FDA after a panel of advisers voted in favour of approval last month, despite some concerns about side effects.

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Diarrhoea is a commonly reported problem with Puma’s drug in clinical trials so far, but neratinib has a major advantage over Roche’s drug: it is likely to be much cheaper.

This gives Puma the room to undercut Roche, while still ensuring it makes a healthy return on its investment in the former Wyeth/Pfizer drug, the only molecule in its pipeline.