All eyes in the biotech world on Arena's diet pill

Today belongs to Arena Pharmaceuticals' ($ARNA) experimental weight drug. Biotech industry watchers are paying close attention to an FDA advisory committee today that will judge the biotech's drug, lorcaserin, a contender in the race to break a long dry spell in U.S. approvals for diet pills. Trading for the stock has been halted.

The advisory committee session has been one of the most highly anticipated events of the week in the biotech world, with the FDA expected to factor in the panel's vote in the agency's decision on approval. Biopharma commentator Adam Feuerstein from The Street has been blogging live from panel venue this morning, noting that the much-anticipated vote on whether the non-agency experts will endorse the weight drug is likely to happen later this afternoon.

Safety concerns have plagued Arena's and others' past tries to gain approval of new anti-obesity remedies, and the risks of lorcaserin are expected to weigh most in the advisers' votes on whether to recommend the treatment for approval. FDA staff harped on the potential risks of malignancies and heart problems developing in patients on the drug, in a briefing released on Tuesday. And they brought up concerns about the impact of lorcaserin on the 5HT2 receptor in the brain that is nonspecifically targeted with the banned fen-fen weight drugs, which were pulled off the market more than a decade ago after patients on the drugs suffered heart valve damage.

In one post this morning, Feuerstein wrote that an FDA official said Arena's data on 5HT2 receptor activity was sufficient to settle the receptor selectivity issue. Heart valve risks are a chief concern of regulators, and the advisory committee recently recommended that all new diet drugs undergo cardiovascular risk studies even when there is no evidence of heart problems in clinical trials.

Stay tuned for updates on the outcome of the FDA panel later this afternoon.  

- here's a link to Feuerstein's live blog