In Real World, Adherence Low to Spinraza Treatment, Data Show
A significant proportion of people with spinal muscular atrophy (SMA) do not remain on Spinraza (nusinersen) or receive treatment injections as prescribed, according to a U.S. insurance claims analysis.
“SMA can be treated, but it is important that patients receive their scheduled doses of medicine as prescribed and stay on treatment,” the researchers wrote.
Instead, “the study showed that a low number of patients with SMA, particularly those older than 18 years with no spinal problems, remained on [Spinraza] for the intended time and received the treatment as prescribed,” the team wrote.
The researchers recommended further studies to examine the reasons for the low Spinraza adherence — whether patients received their scheduled doses — and persistence, or how many remained on treatment.
Difficulties traveling to a clinic or problems with scheduling, patient preference, or insurance restrictions may be possible reasons why so few adults fully complied with their Spinraza treatment regimen, the team suggested.
Investigating rates of adherence, persistence
The claims analysis was published in the journal Advances in Therapy, in the study “Adherence and Persistence to Nusinersen for Spinal Muscular Atrophy: A US Claims-Based Analysis.”
The study was led by scientists from Genentech, a subsidiary of Roche, which markets the oral SMA therapy Evrysdi (risdiplam). Evrysdi, which was in development when the present study was being conducted, was approved in the U.S. as a treatment for SMA in August 2020.
Spinraza, by Biogen, was the first treatment approved for SMA in the U.S., and is designed to increase the levels of SMN protein in cells. Those levels are abnormally low in people with SMA.
Administered directly into the spinal canal — a process called an intrathecal injection — Spinraza treatment begins with four initial loading doses. Three are given in two-week intervals and the fourth one month later; after that, patients receive maintenance doses three times a year.
However, whether patients adhere to this regimen and remain on treatment in the real world is unclear.
Using the U.S.-based IQVIA PharMetrics Plus claims database, researchers investigated the real-world adherence and persistence to Spinraza among patients with SMA.
A database search identified 179 SMA patients (53.1% female) who received Spinraza between July 1, 2017, and Dec. 31, 2019. Overall, 40.8% of the participants were adults, 31.3% were adolescents aged 3–17, 19% were children ages 2–12, and the remaining 8.9% were infants, less than 2 years of age.
The most common spinal complication among patients was scoliosis, a sideways curvature of the spine, seen in 45.8%. Most patients had commercial or self-insured coverage and their average age at the start of treatment was 17.6 years.
Spinzara adherence was defined as the percentage of participants receiving at least their expected doses at each dosing interval. Grace periods — the number of days beyond the scheduled dose — of seven days for each loading dose, and 28 days for each maintenance dose, were allowed in the adherence analysis.
Adults particularly bad at staying on Spinraza treatment
Among the 171 patients with sufficient eight-week follow-up data, 80 (47%) had completed the four loading doses as prescribed. During the maintenance phase, the proportion of patients adhering to Spinzara declined further from 46% after about six months, to 41% after one year, to 39% after two years.
Adherence to Spinraza treatment during the first year was lower in patients younger than 18 than it was in adults. But after one year, adherence was higher in younger patients. Moreover, more patients with spinal complications adhered to Spinzara over two years compared with those without spinal complications.
“Having spinal complications or younger age of onset may be a reflection of more severe SMA, and these patients and their families may require more interactions in the healthcare setting that lead to higher adherence,” the team noted.
Spinzara persistence was defined as the percentage of participants who remained on treatment over a follow-up period of two years. Discontinuations were defined as having two consecutive missed doses and continuous enrollment on the date of the second missed dose, which ensured the discontinuation record remained in the database. Allowed grace periods were the same as in the adherence analysis.
Data revealed that Spinzara persistence was 67% after six months, 57% at one year, and 55% after two years of treatment.
A secondary sensitivity analysis was conducted using a different discontinuation definition: one missed dose and grace periods of seven days for each loading dose and 60 days (two months) for each maintenance dose. Here, data showed treatment persistence was 53% after six months, 42% at one year, and 35% after two years of treatment.
“The lower persistence estimates in the sensitivity analysis show that the algorithm is behaving as intended and that there was a group of patients who skipped one dose but restarted treatment afterward,” the researchers wrote. “These patients are designated as discontinued in the sensitivity analysis, but not in the [first] analysis in which patients had to have missed two consecutive doses.”
While Spinzara persistence was similar across all age groups, patients with spinal complications remained on treatment longer versus those without spinal complications.
“The findings from this study suggest that adherence and persistence to [Spinzara] treatment are low,” the researchers wrote. “Future research should confirm these results using other methodology and explore possible reasons for low adherence and persistence to nusinersen treatment, such as clinical or logistical factors, patient preferences, and payer restrictions.”
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