San Diego-based Neurocrine will pay Voyager Therapeutics $165 million upfront as part of a larger drug development pact, it was announced Jan. 29.

The $165 million breaks down into a $115 million upfront payment and a $50 million equity investment. In addition, Massachusetts-based Voyager is eligible for $1.7 billion in development, regulatory and commercial milestone payments across four neurological gene therapies included in the deal.

Neurocrine gained four potential treatments, including for Parkinson’s disease and Friedreich's ataxia — an inherited disease that causes difficulty walking, a loss of sensation in limbs and other issues. The two others have yet to be determined, the companies stated

The furthest along of the four is VY-AADC for Parkinson’s disease, currently in a phase 2, or mid-stage trial. It’s designed to convert levodopa to dopamine, which could restore motor function in patients and improve symptoms. Neurocrine is funding both phase 2 and phase 3 development.

Once phase 2 data is released, Voyager has two options. It could co-commercialize VY-AADC and split costs and profits, while receiving milestones and royalties on sales outside the U.S. — or grant Neurocrine full commercial rights in exchange for milestone payments and royalties from global sales.

The deal marks a major pipeline expansion for Neurocrine, which built a reputation on the drug ingrezza, the first approved treatment for the nervous system disorder tardive dyskinesia.