[This report has been updated from an earlier edition to include comment from Pfizer on the end of the collaboration.]


Pfizer has terminated its up-to-$70 million collaboration with Repligen for the development of compounds to treat spinal muscular atrophy (SMA) after just over two years and $7 million.

As a result, Pfizer has handed back to Repligen its SMA compound RG3039 (also known as PF-06687859) as well as an undisclosed number of compounds in preclinical phases.  On January 26, Pfizer gave Repligen its notice of termination, which takes effect April 26, Repligen said today in a Form 8-K filing with the U.S. Securities and Exchange Commission.

The termination comes less than a month after Repligen received a $1 million payment from Pfizer for achievement of an undisclosed milestone.

The payment was part of a total $7 million in upfront and milestone payments shelled out by Pfizer to Repligen under their collaboration, Repligen said on January 8. At the time, Repligen was still eligible for up to $63 million in milestones, plus royalties on any future sales of compounds developed through the partnership.

In a statement to GEN, Pfizer said it remained committed to rare disease research, citing significant unmet medical need.

“Our portfolio currently consists of 22 marketed medicines approved worldwide that treat rare diseases in the areas of hematology, neuroscience, inherited metabolic disorders, pulmonology, and oncology, and our investigational programs in rare disease include seven programs from Phase I through registration,” Pfizer stated. “Pfizer will continue to leverage our legacy expertise, technology platforms and leading capabilities in collaboration so that we can advance the research and development in rare diseases to ultimately lead to potential treatments for those we serve.”

Pfizer and Repligen entered into their up-to-$70 million collaboration December 28, 2012, and announced it on January 3, 2013. Under their deal, Repligen agreed to oversee completion of the first two cohorts of an active Phase I trial evaluating RG3039 in healthy volunteers, as well as provide technology transfer services to Pfizer. In return, Pfizer agreed to assume full responsibility for the SMA program, including the conduct of any registration trials necessary for product approval.

RG3039 previously received U.S. Orphan Drug and Fast Track designations for the treatment of SMA from the FDA, as well as the EU’s Orphan Medicinal Product designation. The compound is an inhibitor of the enzyme DcpS and showed promising preclinical results by improving survival and motor function in mice with SMA.

The preclinical development of RG3039 was funded and directed by the patient organization Families of SMA, through an investment of more than $13 million.

Last June at the 2014 SMA Conference, Pfizer presented results of a Phase I trial for RG3039 that showed significant inhibition of DcpS in the blood, but no change in the SMN protein, in which SMA patients show a deficiency.

“We expect that efficacy will require an increase in SMN,” according to a summary of conference keynote speeches and drug developer presentations posted by Cure SMA on its website.

Other companies pursuing SMA treatments include Trophos, whose Phase II/III-completed SMA compound olesoxime (TRO19622) is being acquired along with the company by Roche for up to €470 million (about $543 million), in a deal announced January 16. Two days earlier, Isis Pharmaceuticals said it earned a $7 million milestone payment from Biogen Idec related to the advancement of an ongoing open-label extension study of ISIS-SMNRx in children with SMA.

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