Biogen Korea is strengthening its position in the local spinal muscular atrophy (SMA) market with expanded reimbursement benefit of Spinraza (ingredient: nusinersen), the company said Thursday.

Biogen Korea held a press conference at the Conrad Hotel in Yeouido, Seoul, Thursday, to commemorate the expansion of the reimbursement criteria for Spinraza to include type 3 SMA patients whose symptos appear after three years old.

Although there's no significant impact on life expectancy for SMA type 3 patients, the treatment could improve their quality of life, particularly in areas like mobility.

SMA is a rare neuromuscular disorder that causes progressive muscle wasting due to damage to motor neurons in the spinal cord and brainstem.

It occurs when the SMN1 gene on chromosome 5q, responsible for producing the SMN protein (Survival Motor Neuron Protein), doesn't function correctly.

This results in a decline in motor neurons, leading to weakening and atrophy of muscles. Severe symptoms can lead to an inability to breathe or swallow on one's own, resulting in death.

The onset and prognosis of SMA vary based on SMN2 expression levels, and it's classified into Types 1 through 4 based on the timing of the symptom onset.

Type 1, which starts before six months of age, usually results in death by the age of two. Type 2 patients, whose symptoms appear between seven months to 18 months, often have mobility issues, with 70 percent dying before the age of 25. Types 3 and 4 have a life expectancy comparable to the general population, but type 3 patients gradually lose motor functions and become dependent on wheelchairs.

Spinraza is an RNA therapy that increases the amount of protein produced by the SMN2 gene. It offers a foundational treatment for SMA and has been covered by health insurance in Korea since 2019.

However, until now, the reimbursement criteria were limited to patients who received a genetic diagnosis of a defect or mutation in the 5q SMN-1 gene, showed clinical symptoms and signs related to SMA before the age of 3, and were not using a permanent artificial respirator.

This led to SMA types 3 and 4 patients not receiving reimbursement benefits due to their later onset and uncertain clinical efficacy of the treatment.

Biogen Korea was able to remove the age restriction and expand the criteria to include type 3 patients, allowing patients with type 3 SMA, whose symptoms appeared after the age of 3, to also be reimbursed.

Speaking at the conference, Professor Park Hyung-jun of the Department of Neurology at Gangnam Severance Hospital emphasized that until now, Type 3b SMA patients have been relying on physical and rehabilitation therapies despite their progressive muscle weakness.

SMA Type  3 has two categories -- 3-A and 3-B.  The distinguishing features between these two subtypes of type 3 SMA are age of onset and severity.

Patients with SMA subtype 3-A experience segmental distal weakness and a developmental plateau beginning before three years of age, whereas patients with SMA subtype 3-B will have an onset of segmental proximal sometime between age three and age 10 years old.]

"With the expanded reimbursement criteria, Type 3b patients can now expect improvements in motor function and quality of life," Park said. "Studies from various countries have shown improvements in motor function indicators in later-onset SMA patients treated with Spinraza."

During the press conference, Biogen Korea Medical Lead Choi Jung-nam highlighted the accumulated safety and effectiveness data of Spinraza.

"The drug has a rare track record of over eight years of long-term follow-up data in the rare disease field, with more than 14,000 patients have been observed for over 7.6 years in real clinical settings," Choi said. "Also, as Spinraza is administered directly into the central nervous system, it maintains a consistent concentration regardless of a patient's age or weight, ensuring stable safety and efficacy."

Choi also stressed that Biogen Korea continues its efforts with various initiatives, such as the TISMA digital medical information platform for patients and educational content to improve patients' motor functions and daily lives.

Spinraza looks to gain the upper hand in the SMA market share competiton

With Spinraza expanding its insurance benefits, it hinted at the possibility of differentiation from competing drugs compared to Novartis' Zolgensma, the one-shot treatment, and Roche's Evrysdi, the oral medication.

Zolgensma received insurance benefits in August of last year, while Evrysdi started to receive insurance benefits in October of this year.

The drug with the highest sales among the three drugs in Korea is Spinraza, which recorded sales of 143 billion won in the first quarter of this year. While sales of Spinraza had once surpassed 200 billion won in quarterly sales in the first quarter of 2020, it has recently shown a decline with the emergence of Zolgensma and Evrysdi. This year's first-quarter sales decreased by 18 percent compared to the previous year.

Next, the 'one-shot treatment' Zolgensma recorded sales of 54 billion won, ranking second. On the other hand, the only oral medication, Evrysdi, had a mere quarterly sale of 3 billion won.

This was due to the fact that Evrysdi was not receiving reimbursement at that time, and is in contrast with global market trends.

In global sales, Evrysdi is threatening Spinraza's position by surpassing Zolgensma.

As Evrysdi received insurance benefits last month, industry officials expect that the competition to gain market share in the SMA market will intensify.