Ultragenyx has picked up an option to acquire GeneTx and its preclinical antisense oligonucleotide. The drug, GTX-102, is designed to treat the rare neurogenetic disorder Angelman syndrome.

GeneTx grew out of an Angelman patient advocacy group that sourced donations to take GTX-102 through preclinical development. The asset, which originates from the Texas A&M University System, is designed to inhibit expression of UBE3A-AS, the antisense transcript that regulates the silencing of the gene at the root of Angelman syndrome.

GeneTx expects to file to start testing the candidate in humans in the first half of next year. With that key event coming up, GeneTx has secured an injection of cash and support from Ultragenyx, which will provide strategic guidance and clinical expertise to its partner in the run-up to the IND.

The deal gives Ultragenyx the option to swoop in for GeneTx at a couple of points in the development of GTX-102. In return for the initial $20 million upfront, Ultragenyx has secured the option to acquire GeneTx any time up to 30 days after FDA acceptance of the GTX-102 IDN filing.

Alternatively, Ultragenyx can hold fire until getting a look at phase 1/2 data, but it will have to pay to secure that flexibility. To defer the decision until 30 months after the start of dosing in the phase 1/2 or 90 days after the delivery of data from the trial, Ultragenyx will need to pony up another $25 million in the form of an option extension payment.

GeneTx and Ultragenyx plan to collaborate on the phase 1/2 trial. If Ultragenyx exercises its option, it will cover all the costs of developing and commercializing GTX-102 and put itself on the hook for milestones and royalties.

Buying out GeneTx would move Ultragenyx onto turf contested by a number of companies. Ovid Therapeutics expects top-line data from a phase 3 trial of its candidate next year. Further back, Biogen, Roche and others explored treating the disease via antisense therapies and other means.