Biogen Idec has agreed to pay Isis Pharmaceuticals up to US$299 M to gain rights over ISIS-SMNRx, an antisense drug in Phase I development for spinal muscular atrophy (SMA). Isis will be responsible for global clinical development up until the completion of registrational Phase II/III trials and will receive advice on clinical trial design and regulatory strategy from Biogen Idec, which has the option to license ISIS-SMNRx prior to the completion of the first successful Phase II/III study. The deal highlights the pharmaceutical industry’s growing interest in rare diseases such as SMA.