Does Spinraza provide benefit after treatment with Novartis' gene therapy Zolgensma? Biogen aims to find out

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Biogen is starting a phase 4 trial of Spinraza in patients who've already had treatment with Novartis' Zolgensma. (Biogen)

Spinal muscular atrophy treatment has changed and improved dramatically in recent years, first with the launch of Biogen’s Spinraza drug and then with Novartis’ gene therapy Zolgensma. Now, Biogen aims to find out whether its med could help Zolgensma patients who still need more treatment.

The company is planning a new trial to test Spinraza in those patients, despite the fact that Novartis’ gene therapy is intended to be a one-time treatment for the rare disease. Some could still benefit from Spinraza after receiving the gene therapy, pediatric neurologist Crystal Proud told FiercePharma.

Proud, a member of the phase 4 trial's steering committee, has treated 10 SMA patients with Zolgensma, and she has "several ... that I would consider exploring this potential benefit with," she said. Investigators will enroll patients based on motor function scores, respiratory insufficiency, abnormal swallowing and more. 

The trial will answer a question that’s “very meaningful to the SMA community and I think one that will affect how we approach treatment for the long term,” she added. 

Biogen plans to submit plans for the study to regulators in the coming months and enroll the first patients in early 2021. The Respond study will enroll 60 children under 3 who could benefit from Spinraza after treatment with Zolgensma, as determined by study investigators. Doctors will track clinical responses such as patients' motor function, their need for respiratory support, and their ability to swallow and eat. 

RELATED: With 'remarkable' data, Biogen's Spinraza sharpens its case against Novartis gene therapy 

Biogen won FDA approval for Spinraza in late 2016 and in the years since, the rollout has exceeded expectations as the drug has become a top growth driver. Spinraza sales reached $2.1 billion last year. 

Novartis’ rival gene therapy debuted last year and generated $361 million.

Zolgensma's approval is limited to patients 2 and younger, but Biogen has been pushing to compete for those young patients. Last year, the company’s Nurture study showed that patients treated with Spinraza before symptoms went on to reach development milestones at ages typical for babies without SMA. A Biogen exec called the result “remarkable” and "well beyond anything that has been previously reported or ever seen in the natural history of patients with SMA.”

Patients in that study received their first treatments before 6 weeks of age, and investigators tracked them for up to four years.

RELATED: Roche's risdiplam clears another phase 3, setting up SMA showdown with Biogen and Novartis 

Meanwhile, new competition in SMA could be on the way from Roche and PTC Therapeutics. The partners’ risdiplam faces an FDA decision this summer after posting positive phase 3 data earlier this year.