MPNforum Magazine

Fedratinib (SAR-302503):  Clinical hold on trial, Patients to stop taking drug

It’s hard to know what to make of Sanofi’s decision Thursday, November 14, to halt the Phase III clinical trial of its JAK-2 inhibitor fedratinib (SAR-302503).   As recently as May positive results from the trial were being heavily promoted and plans to file for FDA approval after ASH were reported to be in place. All reports through last week were upbeat and there were high hopes for the ASH report, three weeks away.

And then, out of the blue, MPN social media lit up when the administrator of the popular Myelofibrosis Facebook page posted notice that her physician told her to stop taking the Sanofi drug immediately and come in for a neurological exam and consultation after the weekend. The FDA, she was told,  had halted the trial and all participants were to have pharmacokinetics (PK) testing.  

Friday, November 15, a Sanofi spokesperson called MPNforum to alert patients a clinical hold had been placed on the trial because of four cases of Wernickes encephalopathy, one of which proved fatal. “In the interest of patient safety, we are putting a temporary clinical hold on fedratinib and have advised all clinicians to immediately discontinue the drug until further work can be done. “ Presently there are 48 patients on trial in the US and approximately 300 wordwide

Wernicke’s encephalopathy is a neurological disorder often associated with poor nutrition. It presents with biochemical lesions of the central nervous system after exhaustion of B-vitamin reserves, particularly thiamine.  Wernicke’s causes bleeding in the lower brain that controls the nervous and endocrine systems.

Sanofi is planning to issue a detailed press release on Monday, November 18 and make  medical experts available via teleconference, to be announced.

The event is reminiscent of Incyte’s experience with a single case of progressive multifocal leukoencephalopathy (PML) in a patient with myelofibrosis after initiation of ruxolitinib therapy earlier this year.

Whether or not the JAK-2 inhibitor is directly involved in either case has not been established.