ACR preview – Benlysta and R788 in the spotlight

Analysis

Next week’s annual meeting of the American College of Rheumatology (ACR) will throw the spotlight once more, if more light is possible, on Benlysta, Human Genome Sciences’ potential breakthrough treatment for lupus, one of the biggest unmet medical needs.

Full details of the first phase III trial, headline results from which lit a fire under HGS’ share price in July, will be revealed providing an insight into the drug’s efficacy and safety; given that most analysts have been wowed by the initial trial results, any slight doubts over the drug’s commercial potential could be damaging. Other headline acts at ACR include Rigel Pharmaceuticals’ rheumatoid arthritis (RA) drug, R788, with detailed phase IIb results helping to shed more light on the somewhat mixed data reported so far, which could help or hinder ongoing partnership discussions.

Revolutionary treatment

HGS have already reported positive and hugely encouraging data from the Bliss-52 phase III trial of Benlysta, providing hope that a disease-modifying therapy could soon be available to treat patients with lupus (Positive Benlysta data leaves Human Genome with new bulls, July 20, 2009). Current treatment options for lupus are largely unsatisfactory, including immunosuppressants and corticosteroids which can have serious side effects.

Since these results were published, analysts have dramatically upgraded their forecasts for Benlysta; previously consensus sales in 2014 were heavily risk adjusted at just $182m, whereas that figure is now a whopping $1.3bn according to latest EvaluatePharma forecasts.

Given the huge expectations now placed on Benlysta the full trial results clearly need to confirm the efficacy and safety profile revealed so far. Whilst the detailed Bliss-52 data is important, results from a second phase III trial, Bliss-76, due in November are ultimately more significant with HGS and partner GlaxoSmithKline hoping to file the drug early next year.

Meanwhile, a number of earlier stage products are in the pipeline for lupus which will try and snap at the heels of Benlysta (Therapeutic focus – Lupus needs shots on goal to hit the mark, June 12, 2009).

Immunomedics recently reported encouraging phase IIb data for their lupus candidate, Epratuzumab (IMMU-103), although interestingly their application to present the detailed data in a late-breaking abstract was rejected by ACR. The Benlysta data will be one of the six late-breaking abstracts on October, 20.

Detailed phase IIb data on another lupus candidate, ImmuPharma’s Lupuzor which is now in Cephalon’s hands, will not be presented at ACR but is expected within the next few weeks. Positive interim results were revealed in February which triggered Cephalon to exercise its option to license the drug.

Rigel’s mixed data

Two other late-breaking abstracts at ACR will reveal detailed results for Rigel’s oral syk kinase inhibitor drug, R788. Earlier this year Rigel reported mixed results from two phase IIb trials (Rigel comes crashing down to earth on RA data, July 24, 2009).

Positive results from the TASKi2 trial in RA patients who had failed on standard small molecule treatment methotrexate, were followed by a disappointing response rate in the TASKi3 trial for patients who had failed on anti-TNF biological products.

A surprisingly high placebo response rate appears to have accounted for the failure in TASKi3, so the full results may provide an insight as to why this occurred and could help to soothe some concerns over the drug’s potential.

This will be important because the company has made itself a hostage to fortune in some respects by raising significant expectations that a big pharma partner will be secured before phase III trials start early next year. As such the data could spark renewed interest from potential partners who so far have been waiting in the wings.

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