Sprycel, Tasigna, and Gleevec battle for supremacy in CML treatment.

FDA accepted an sNDA for Bristol-Myers Squibb (BMS) and Otsuka Pharmaceutical’s chronic myeloid leukemia (CML) drug, Sprycel®, and has granted the application priority review status. The sNDA specifically relates to use of the BCR-ABL inhibitor for the treatment of adult patients with newly diagnosed CML in chronic phase. The projected FDA action data is October 28.

Sprycel was originally developed by BMS. The drug has been commercialized in the U.S., Japan, and major European countries in collaboration with Otsuka. Sprycel is already approved in the U.S. for the treatment of all stages of CML in adult patients who are resistant or intolerant to prior therapy including Novartis’ Gleevec/Glivec. Sprycel is separately approved for treating adults with Philadelphia chromosome (Ph+) acute lymphoblastic leukemia (ALL) who are resistant to or intolerant to prior therapy.

The latest regulatory application for the drug is based on positive data from the international Phase III Dasision trial, which directly compared once-daily oral Sprycel 100 mg with Gleevec 400 mg as first-line treatment of newly diagnosed, chronic phase CML. BMS says the results, which were presented in June, showed that 77% of Sprycel-treated patients achieved a confirmed CCyR by 12 months compared with 66% of patients receiving Gleevec.

The time to CCyR was also shorter for Sprycel patients and was achieved by 54% of Sprycel patients within three months, BMS points out. In comparison with Gleevec therapy, treatment using Sprycel also doubled the likelihood that patients achieved achieve a major molecular response (MMR) during the course of the study.

Sprycel achieved sales of $421 million for BMS in calendar year 2009, up 49% on 2008. Sales in the first quarter of 2010 were $131 million.

In February Novartis confirmed that its latest CML drug Tasigna® had been granted priority review by FDA for the treatment of adult patients with newly diagnosed chronic phase Ph+ CML . At the time, the firm said that if approved, Tasigna would be the first drug for newly diagnosed patients to become available since the approval of Glivec in 2002. Phase III trial data had confirmed that Tasigna exceeds Glivec in every measure of efficacy, including prevention of disease progression at 12 months. Tasigna is currently approved in over 80 countries for the treatment of chronic phase and accelerated phase Ph+ CML in adult patients resistant or intolerant to at least one prior therapy including Glivec.

Gleevec/Gliviec is Novartis’ second-biggest selling drug behind the blood pressure medication Diovan. Sales of Gleevec/Glivec in 2009 reached $3.95 billion, up 12% on 2008. Sales of Tasigna were $212 million in 2010, up 145% in local currencies compared with the first quarter of 2009.

Meanwhile, ChemGenex is working to develop a validated mutation test that can be used alongside its FDA-submitted CML drug, Omapro™, which has been developed specifically for CML patients with the Bcr-Abl T3151 mutation. In March the agency’s Oncology Drugs Advisory Committee decided that a test for the mutation should be developed before Omapro can be considered for approval.

Although Omapro was submitted to FDA on the basis of positive data from study CML-202 in patients with T3151 mutations, the advisory committee was primarily concerned that multiple assay methods were used for detecting T3151 mutations. It concluded, “The lack of having a uniform in vitro diagnostic test creates uncertainty about patient selection both in this trial and, more importantly, in a post-approval setting. If a patient does not harbor the T315I mutation but is falsely identified as having such a mutation by these unreviewed assay methods, the patient may not receive more effective, less toxic therapy such as dasatinib or nilotinib. Conversely, patients with a false negative test result would receive an ineffective therapy.”

The FDA panel was also concerned that the Omapro submission only included efficacy and safety data from 66 patients, which it says was insufficient to make claims for efficacy of the drug in patients at the accelerated and blast phase of the disease.

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