Dozens of doctors in the US have signed an open letter to the US FDA taking it to task over its rejection of Genzyme's multiple sclerosis (MS) therapy Lemtrada late last year.
Going against the recommendations of its own advisory committee, the agency turned down Lemtrada (alemtuzumab) on safety grounds, saying that Sanofi subsidiary Genzyme had not provided sufficient evidence that its benefits outweighed it risks.
The FDA asked for new studies of the drug that could delay approval by two years, although Genzyme said quickly it planned to appeal.
Now, two MS specialists - Alasdair Coles and Alastair Compston - have written a letter to The Lancet on behalf of 70 physician signatories to "urge the FDA to re-evaluate and revoke this decision", pointing out that Lemtrada has been approved in other markets including Canada, Europe, Mexico, and Australia.
Coles and Compston were both involved in the clinical trials of Lemtrada and say they have "complete confidence in the results of the phase II CAMMS223 study and phase III CARE-MS1 and CARE-MS2 studies" which supported the marketing application for the drug.
They take issue with the FDA's verdict that, because the trials were not 'double-blind', the findings were compromised. A double-blind study means that neither the patient taking the drug nor the physician giving the drug knew whether the patient was receiving the drug being assessed or a comparable treatment/placebo.
"The FDA was informed from the outset that … double-blinding [was] not possible for alemtuzumab because of its well-publicised and predictable acute infusion reactions," wrote Coles and Compston, claiming that so-called 'rater-blinding' is routine in MS trials.
In fact, Lemtrada achieved an impressive feat - showing superiority to an active comparator (interferon beta) - which few other MS drugs have attempted.
The FDA's decision "prevents patients in the USA from access to an important treatment option in multiple sclerosis that offers high efficacy with infrequent dosing," say the physicians.
Lemtrada is one of the cornerstones of Sanofi/Genzyme's aspirations in MS along with the oral drug candidate Aubagio (teriflunomide), which was cleared for marketing in the US in 2012.
Despite the increasing level of competition in the MS sector Lemtrada has been tipped as a $500m-plus product at peak, providing it can secure US approval. The drug achieved sales of $2m in the short period it was available outside the US last year.