Biogen loses another pipeline drug to toxicity concerns

Just a few days after calling time on its Eisai-partnered Alzheimer’s drug elenbecestat, Biogen has another pipeline casualty – this time its idiopathic pulmonary fibrosis (IPF) therapy STX-100.

The decision – announced in an update posted on ClinicalTrials.gov – was taken because of safety concerns with the antibody drug, a humanised monoclonal antibody designed to disrupt alpha V beta 6 integrin and the TGF-beta pathway.

The demise of the drug draws a line under Biogen’s $75m upfront acquisition of Stromedix in 2012, when STX-100 was looking like a potentially important new therapy for fibrotic diseases based on preclinical and early clinical testing.

Biogen actually originated the drug and licensed it out to Stromedix – a start-up headed by its former R&D chief Michael Gilman – before taking it back in-house in the takeover deal, which also included almost $490m in milestone payments. STX-001 was renamed BG00011

At the time, there were no FDA-approved treatments for the estimated 200,000 people in the US with IPF, an almost uniformly fatal disease in which patients experience progressive difficulty breathing due to scarring of the lung.

In the interim, two drug treatments – Boehringer Ingelheim’s Ofev (nintedanib) and Roche/Genentech’s Esbriet (pirfenidone) – have been approved by the FDA for the disease and grown into blockbuster products with sales of $1.2bn and $1bn, respectively.

Boehringer has its eyes on a follow-up treatment for IPF, and in July licensed an early-stage autotaxin inhibitor BBT-877 from South Korea’s Bridge Biotherapeutics in a €1.1bn ($1.2bn) deal.

The placebo-controlled SPIRIT trial of a once-weekly subcutaneous formulation of STX-001 got underway last year with a target enrolment of 109 subjects, and was due to come to an end towards the end of November.

News of the abandoned study was broken by analyst Brian Abrahams of RBC Capital Markets, who suggested that Biogen would shrug off the demise of STX-001 as it “was not one of its higher-profile pipeline agents”.

He added however that “it does underscore some of the relatively high-risk nature of [Biogen’s] pipeline and removes one of their potential internal diversification opportunities”.