UPDATED: Ariad shares plunge again after safety fears force halt to Iclusig sales

Shares of badly battered Ariad Pharmaceuticals ($ARIA) took a fresh dive this morning after the biotech reported that it is jerking its leukemia drug Iclusig from the market at the request of the FDA, two weeks after the drug developer opted to shutter its Phase III confirmatory study after seeing evidence of an elevated risk of blood clots among patients.

The stock is down 40% this morning, off 80% for the month.

Earlier this month, the FDA--which provided an accelerated approval for the therapy--placed a partial hold on the Phase III trial after the blood clot incidents were reported. Today, the company said it will temporarily stop selling the drug for chronic myeloid leukemia after getting a request from the FDA. The sales halt will go on "while it continues to negotiate updates to the U.S. prescribing information for Iclusig and implementation of a risk mitigation strategy," notes a brief release.

"Ariad believes that Iclusig is an important medicine for patients with resistant or intolerant Philadelphia-positive leukemias and is actively working with the FDA on actions to achieve the resumption of marketing of Iclusig," states the release.

There's been considerable discussion among industry observers on Twitter about the likelihood of limiting sales of the drug to patients who have already failed one or two other available alternatives, as well as a possible subpopulation of patients most likely to benefit. It's uncertain now how big a market Ariad could be left with.

In its release today, the FDA noted its serious concerns about the danger Iclusig presents to patients. "Currently, approximately 24% of patients (nearly one out of four) in the Phase 2 clinical trial (median treatment duration 1.3 years) and approximately 48% of patients in the Phase 1 clinical trial (median treatment duration 2.7 years) have experienced serious adverse vascular events, including fatal and life-threatening heart attack, stroke, loss of blood flow to the extremities resulting in tissue death, and severe narrowing of blood vessels in the extremities, heart, and brain requiring urgent surgical procedures to restore blood flow. In some patients, fatal and serious adverse events have occurred as early as two weeks after starting Iclusig therapy." 

The FDA added: "At this time, FDA cannot identify a dose level or exposure duration that is safe."

Iclusig was given an accelerated approval for resistant or intolerant chronic myeloid leukemia and Philadelphia-chromosome positive acute lymphoblastic leukemia patients last December on Phase II data, which arrived just 5 years after clinical trials began for the drug. And the biotech had ambitiously pursued a slate of studies aimed at broadening its use among leukemia patients as it began marketing the drug at a cost of $115,000 a year.

The sudden end of the study and marketing efforts in the U.S. leaves Ariad in a perilous position. The company was heavily focused on rolling this treatment out in the U.S. and Europe while devoting a considerable amount of attention to R&D projects aimed at expanding its use.

- here's the release from Ariad
- here's the statement from the FDA