While the world's media remains focused on Kensington Palace, Roche (RHHBY.OB) today confirmed that its succession plans for its best-selling drug Rituxan were also firmly in place following the early announcement of more positive Phase III data for GA101 (obinutuzumab). The final part of the CLL11 trial, which demonstrated the new drug's superiority over Rituxan in a head-to-head trial for chronic lymphocytic leukaemia (CLL) in elderly patients, should help the Swiss giant to blunt some of the looming generic threats to the blockbuster antibody when it loses patent protection in Europe later this year. It also sets GA101 up to take the crown in the larger indication of non-Hodgkin lymphoma.
Early Promise
Today's interim analysis of the 192-patient CLL11 study demonstrated that GA101, combined with the chemotherapy drug chlorambucil, met its primary endpoint of progression-free survival compared with Rituxan and chlorambucil. Roche has not chosen to report detailed data, preferring to unveil the statistical findings at this year's American Society for Hematology conference in December.
While the breakdown of the trial results will be hotly anticipated, one indication as to the strength of the outcome is the fact that the final data points were reached well ahead of the original early 2014 completion date, indicating a very statistically significant difference between the two treatment arms. Roche has not been slow to capitalise on the success of previous trials in CLL -- GA101 has been filed in both the U.S. and Europe. It has also gained both breakthrough therapy designation and priority review in the U.S., leading some to predict that it could be on the market by the end of the year.
The Science Bit
The drug's effectiveness is thought to be down to its glycol-engineered formulation, whereby modified specific sugar molecules in GA101 interact with immune cells, helping it mobilise patients' immune systems to attack cancer cells. The drug also binds to the B-cell surface marker CD20 to induce cell death (see "Therapeutic Focus -- The Tide Turns Slowly In Chronic Lymphocytic Leukaemia," June 25, 2013).
At the moment, sales forecasts for the double-whammy drug are a modest-looking $316 million by 2018, following a 2014 launch, according to consensus forecasts from EvaluatePharma. Although these have nudged up by almost $100 million since the drug gave a good showing at Asco, what appears to be pegging forecasts back is the fear of generic Rituxan (see "Asco -- GA101 And Arzerra Shape Up To Rituxan As Biosimilars Loom," June 6, 2013).
Because many are predicting that Rituxan biosimilars could be on the market as early as 2016, sales expectations for GA101 are nowhere near the $7.16 billion of sales Rituxan achieved last year. The drug also has yet to gain approval in NHL, an indication where Rituxan makes almost 70% of its sales.
The Right Moves
But GA101 has generated good Phase II data in relapsed NHL patients, which on the surface looks better than rivals Arzerra and Treanda in terms of overall response rate. Roche is also sensibly conducting several head-to-head Phase III studies in NHL with Rituxan, which are due to start reading out in 2015. As such, even with generic competition, if the drug can keep outperforming its rivals as well as its progenitor and get a few more approvals to boot, it could easily exceed the modest expectations currently surrounding it. This would indeed make GA101 a prince among its peers.
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