FDA scrutinizes efficacy of Novartis' cystic fibrosis drug

Ahead of an advisory committee meeting next week, FDA staffers provided some analysis of Novartis' bid to gain approval of an inhaled antibiotic for the chronic genetic disorder cystic fibrosis. After scrutinizing several trials of the Swiss drug giant's inhaled powder formulation of the long-approved antibiotic tobramycin, agency staffers questioned the efficacy of the new version of the drug for CF patients, according to documents posted on the FDA's website.

There are already two approved inhaled antibiotics to attack infections from Pseudomonas aeruginosa in patients with CF, which afflicts about 30,000 patients in the U.S. and often leads to respiratory infections. According to the FDA, one of those approved therapies is an inhaled liquid version of the antibiotic ingredient in Novartis' powder product under review.

In results of one of several studies Novartis ($NVS) undertook for its new inhaled antibiotic, agency reviewers questioned the analysis and potential biases in the data.

"A major limitation of Study C2301 is that the primary analysis excluded 41% of the randomized population. The analysis based on 61 (59%) of the original ITT population of 102 patients is seriously limited as the patients who dropped out could be informative," the FDA review explained. "This limitation could introduce potential biases. The FDA reviewer's sensitivity analysis based on all randomized patients receiving treatment showed a smaller magnitude of treatment effect."

Next Wednesday outside experts on an FDA advisory committee are expected to weigh in on several questions such as whether Novartis has provided enough proof of the efficacy of tobramycin inhalation powder (TIP) and whether the product should be approved.

- get the FDA review docs here
- here's Reuters' take

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