AveXis, which is running a series of pivotal clinical trials testing a gene therapy in babies and children with spinal muscular atrophy (SMA), announced plans to be acquired by Novartis for $8.7 billion in cash.

The merger, to be completed by mid-year, met with the unanimous approval of the boards of directors of both companies, AveXis said in a press release.

Novartis’ per-share acquisition price for AveXis stock is $218, a premium of 88 percent on the company’s closing price as of April 6.

“The commitment, drive and expertise of the entire AveXis team has created significant stockholder value, and we are pleased that Novartis recognizes that value in the potential of AVXS-101,” Sean Nolan, president and CEO of AveXis, said in its release. “With worldwide reach and extensive resources, Novartis should expedite our shared vision of bringing gene therapy to these patient communities across the globe as quickly and safely as possible.”

Five clinical trials — ongoing or soon to start worldwide — are planned for AVXS-101, and likely to decide whether the gene therapy is indeed a “transformative” treatment for SMA types 1–3.

How the merger may affect these studies is not fully clear. But both companies strongly hinted that Novartis’ support will only help to advance AVXS-101 and other AveXis gene therapies in earlier stages of development for diseases like amyotrophic lateral sclerosis (ALS).

“The proposed acquisition of AveXis offers an extraordinary opportunity to transform the care of SMA,” Vas Narasimhan, Novartis’ CEO, said in a separate press release. “We believe AVXS-101 could create a lifetime of possibilities for the children and families impacted by this devastating condition. … We look forward on the closing of the deal to a smooth transition for AveXis employees and welcoming them to Novartis.”

AveXis’ decision to conduct a Phase 3 series of trials — an essential step in requesting approval from regulatory agencies like the U.S. Food and Drug Administration and the European Medicines Agency — came on the heels of highly promising results from a Phase 1 study (NCT02122952) of intravenous AVXS-101 in 15 type 1 SMA infants.

“What was remarkable and what we consider transformative — and frankly all the experts in the SMA field also feel the same — is that we had 100% survival of [these] children at 13.6 months of age, and 100% survival of the children at 20 months of age,” Sukumar Nagendran, AveXis’ chief medical officer, said in a February interview with SMA News Today that focused on AVXS-101’s development and potential.

The therapy is safe and designed to be a one-time treatment with the potential to prevent muscle degeneration throughout a person’s life, Nagendran, speaking to SMA News with AveXis’ chief scientific officer, Brian Kaspar, said in the interview.

Most children, especially those treated with the higher Phase 1 dose, also showed unheard-of improvements, including an ability to sit 30 seconds or longer unassisted, to roll over, and even, in some cases, to walk. No type 1 SMA child has ever been able to sit independently, Nagendran said.

STR1VE (NCT03306277), an open-label Phase 3 study now underway in the U.S. and recruiting, is the first of the pivotal series of trials to open.

Like the Phase 1 study, it is focused on treating type 1 SMA babies under 6 months old with a nonfunctional SMN1 gene, and on comparing the therapy’s efficacy and safety against the well-established natural history of the disease.

A near-identical study, called STR1VE-EU (NCT03461289), is set to start recruiting in May across Europe for type 1 SMA babies younger than 6 months old.

Another Phase 3 trial in type 2 SMA children up to 5 years old, called STRONG (NCT03381729), is also underway and recruiting at sites in the U.S.

Presymptomatic infants under 6 weeks of age but likely to develop SMA types 1, 2, or 3, will be treated with AVXS-101 in the SPRINT trial, expected to open in mid-2018.

SMA patients ages 6 months to 18 years with those disease types may enroll in the planned REACH trial, set to open late this year or in 2019.

AVXS-101 contains the human SMN gene, which is defective in SMA patients, and targets the motor neurons dependent on this gene to survive and thrive. The company has analyzed SMN protein levels produced by the newly replaced gene in repeat animal models, and found no decrease or dilution over time.

Children in the Phase 1 trial treated once with AVXS-101 as long as four years ago still show no signs of “losing any motor milestones,” Kaspar said in the February interview.

AveXis is also developing a gene therapy, AVXS-301, that might treat a genetic form of ALS, and another called AVXS-201 to potentially treat Rett syndrome.