UPDATED: Genmab stock jumps after PhII cancer data raise hopes of speedy approval

Phase II data from Genmab (CPH:GEN) have ratcheted up expectations for a fast-track approval of its Johnson & Johnson ($JNJ)-partnered treatment for double refractory multiple myeloma. Analysts see the data as strong enough to bring the CD38 monoclonal antibody to market in the first half of 2016.

Genmab CEO Jan van de Winkel

J&J subsidiary Janssen trialled the antibody--daratumumab--in 124 patients with the bone marrow cancer multiple myeloma who had already received at least three different lines of treatment, such as Celgene's ($CELG) Revlimid and Takeda's Velcade. In this hard-to-treat subpopulation, daratumumab achieved an overall response rate (ORR) of 29.2% and median duration of 7.4 months, both of which have raised hopes of an expedited filing and approval.

"We believe a sub-20% ORR in the Sirius study would probably be sufficient for approval," Jefferies analyst Peter Welford wrote in a note to investors. The optimism is underpinned by FDA's handling of Kyprolis, the multiple myeloma drug which contributed to Amgen ($AMGN) paying $10.4 billion (€9.1 billion) for Onyx Pharmaceuticals. In a trial of 266 patients who had received two lines of treatment, Kyprolis achieved an ORR of 23% and median duration of 7.8 months.

The data were strong enough for Kyprolis to win approval. And with daratumumab having snagged a FDA breakthrough designation in 2013, analysts and investors are optimistic it will soon join the arsenal of drugs available to physicians treating multiple myeloma. Genmab shares were up 9% in Denmark following the news. Current data will limit daratumumab to use as a salvage therapy, but Janssen is running a suite of trials that could expand the antibody's label and make it a blockbuster.

Late-phase trials of daratumumab as a first-line treatment in combination with other drugs--including Revlimid and Velcade--are already underway. Welford has tipped worldwide sales to top out at $3.5 billion, a figure that would allow Genmab to weather declining sales of its chronic lymphocytic leukemia drug Arzerra.

The upbeat outlook soured somewhat within hours of the data being released when GlaxoSmithKline ($GSK) revealed plans to sell its 7.9% stake in Genmab. GSK was regarded as a potential buyer of Genmab, but those rumors have cooled over the past 5 years. Now, with GSK selling its oncology portfolio to Novartis ($NVS), it views Genmab as a noncore asset. Genmab's stock opened down 5% following the news. 

- read the release
- and the GSK news

Editor's Note: This article has been updated with details of GSK's plan to sell its stake in Genmab. 

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