Changes in secondary endpoints followed same pattern as CRISS
The secondary endpoints similarly showed no statistically significant difference when comparing the lenabasum and placebo groups overall. These endpoints included change in mRSS score, change in forced vital capacity (FVC) percentage and volume, and change in the Health Assessment Questionnaire Disability Index (HAQ-DI) score.
However, the researchers again found that duration of background therapy affected FVC.
“You were more likely to have declined [in FVC] if you were on placebo and more likely to have improved or stayed stable if you were on lenabasum if you were a patient on more than 2 years of immunomodulatory therapy at baseline,” Dr. Spiera reported. “There was evidence for an effect of lenabasum on FVC suggested by post-hoc analyses that considered the effect of background immunosuppressive therapies on outcomes, but those results would require confirmation in additional studies to determine the potential of lenabasum for treating patients with diffuse cutaneous systemic sclerosis,” Dr. Spiera noted in his conclusions.
Serious adverse events occurred in 9.2% of the lenabasum group and 5.8% of the placebo group. Rates of severe adverse events were similar between the lenabasum (14.6%) and placebo (13%) groups.
Is there a subgroup for whom lenabasum would be efficacious?
Although De Vries-Bouwstra of Leiden University Medical Center acknowledged the role of mycophenolate in the trial, she does not think background therapy can totally explain the observation and speculated on other possibilities.
“For example, there were fewer males in the placebo group as compared to the phase 2 study. From previous cohort studies we know that males have higher risk of worsening of skin disease,” she said. “In addition, it could be worthwhile to evaluate antibody profiles of the population under study; some subpopulations defined by autoantibody have higher risk for skin progression, while others can show spontaneous improvement.”
Dr. De Vries-Bouwstra said that, although it’s not currently appropriate to advocate for lenabasum to treat dcSSc, it may eventually become an additional treatment in those who still show active skin or lung disease after 2 years of mycophenolate treatment if future research identifies a benefit from that application. She would also like to see an evaluation of lenabasum’s possible benefits in patients with very early and active inflammatory disease. “Ideally, one could stratify patients based on biomarkers reflecting activation in relevant pathways, for example by using gene expression analysis from skin tissue to stratify,” she said.
Jacob M. van Laar, MD, PhD, professor of rheumatology at University Medical Center Utrecht (the Netherlands), also commented on the potential differences in using the drug in early versus later disease.
“Based on ex vivo analyses of skin samples from systemic sclerosis patients, one would expect such a mechanism of action to be particularly relevant in very early disease, so the observation that it might also be effective at a later disease stage is interesting,” Dr. van Laar told this news organization. “We still have a lot to learn about this complex disease.”
Given that safety does not appear to be a major concern and that there may be a benefit in a subgroup of patients, Dr. van Laar also said he hoped “the company is not deterred by the seemingly negative result of the primary endpoint.”
Dr. Spiera expressed optimism about what this trial’s findings have revealed about management of dcSSc.
“Independent of what lenabasum did or didn’t do in this trial, I think there’s going to be a lot that we’re going to learn from this trial and that we’re already learning and analyzing right now about treating scleroderma,” he said in an interview.
He reiterated the value of allowing background therapy in the trial to ensure it better replicated real-world clinical practice.
“You’re not withholding therapies that we think are probably active from patients with active disease that, once you incur organ damage, is probably not going to be reversible,” Dr. Spiera said. “The downside is that it makes it harder to see an effect of a drug on top of the background therapy if that background therapy is effective. So what we saw in terms of this absence of benefit from lenabasum really may have been a ceiling effect.”
Nevertheless, Dr. Spiera said the findings still strongly suggest that lenabasum is an active compound.
“It’s not an enormously powerful effect, but it probably has a role as an adjunctive therapy in people on stable background therapy who have either plateaued or are getting worse,” he said. “The thing we have to keep in mind also is this was an incredibly safe therapy. It’s not immunosuppressive.”
The trial was funded by Corbus. Dr. Spiera has received grant support or consulting fees from Roche-Genentech, GlaxoSmithKline, Boehringer Ingelheim, Chemocentryx, Corbus, Formation Biologics, Inflarx, Kadmon, AstraZeneca, AbbVie, CSL Behring, Sanofi, and Janssen. Dr. De Vries-Bouwstra has received consulting fees from AbbVie and Boehringer Ingelheim and research grants from Galapagos and Janssen. Dr. Van Laar has received grant funding or personal fees from Arthrogen, Arxx Therapeutics, AstraZeneca, Bristol-Myers Squibb, Eli Lilly, Gesynta, Leadiant, Merck Sharp & Dohme, Roche, Sanofi, and Thermofisher.
A version of this article first appeared on Medscape.com.