Disability Reduction Is a Twist in Negative BTKi RRMS Trial

COPENHAGEN — In two phase 3 head-to-head comparing the Bruton tyrosine kinase inhibitor (BTKi) tolebrutinib to the immunomodulatory teriflunomide for relapsing-remitting multiple sclerosis (RRMS), there was no advantage on the primary endpoint of relapse, but the greater protection against disability, a secondary endpoint, might change thinking about BTKis as a potential MS therapy.

For annualized relapse rate (ARR), which is the basis on which these two drugs were compared, “there was no difference between tolebrutinib and teriflunomide,” reported Jiwon Oh, MD, Medical Director, Barlo Multiple Sclerosis Program, St. Michael’s Hospital, University of Toronto, Canada.

In the similar GEMINI 1 and 2 trials, the ARRs were nearly identical in the first, (0.13 and 0.12), and completely identical in the second (0.11) for tolebrutinib and teriflunomide, respectively.

Although Negative, GEMINI Trials Offer Intriguing Data

These data rule out the study hypothesis that a BTKi offers greater protection against relapse than a commonly used immunomodulator, but Dr Oh suggested the study is still potentially relevant to MS research. Although data on the primary endpoint were disappointing, Dr Oh suggested that the secondary outcomes support an anti-MS mechanism for the BTKi that is different from that of teriflunomide.

“There is hope,” Dr Oh said, when reporting the findings of the GEMINI I and II trials during the latebreaker session at the 2024 ECTRIMS annual meeting. Ultimately, a substantial part of this hope was derived from the consistency of the GEMINI data with the placebo-controlled HERCULES trial of tolebrutinib presented immediately afterwards, but the disparity between the primary and secondary outcomes of GEMINI are, by themselves, relevant, suggesting that targets of treatment change as MS progresses from an acute to a chronic inflammatory process.

BTKi Associated With Reduced Disability

At 3 months, the rate of confirmed disability worsening (CDW) in the pooled GEMINI trials was 18.5% and 14.7% for tolebrutinib and teriflunomide, respectively, producing at 27% reduction in hazard ratio (HR) for this outcome (HR, 0.73; P = .0018). At 6 months, the protection against disability (13.2% vs 9.9%) persisted for tolebrutinib relative to teriflunomide (HR, 0.71; P = .23).

For the outcome of a confirmed disability improvement at 6 months, the higher rate in the tolebrutinib arm did not reach statistical significance (12.8% vs 12.0%), but it did suggest a favorable trend (HR, 1.22; P = .17).

While Dr Oh acknowledged that secondary outcomes can only be considered hypothesis generating when the primary outcome is negative, she said these outcomes provide intriguing support for the potential of this BTKi drug to inhibit “smoldering inflammation.” Even if tolebrutinib was no more effective than teriflunomide against the acute inflammation that drives relapse, the GEMINI trials data support greater inhibition of the chronic inflammation implicated in progression in the absence of flares.

On MRI, the annualized rate of new and enlarging T2 lesions, although numerically higher in the tolebrutinib group, did not differ significantly in either GEMINI 1 (5.6 vs 5.2; P = .46) or GEMINI 2 (5.1 vs 4.4; P = .24). The least mean square difference in brain volume at end of study relative to 6 months into the study was 0.2% less in the tolebrutinib arm than the teriflunomide arm (P = .0002) in GEMINI 1, but the 0.04 numerical advantage for tolebrutinib did not reach statistical significance in GEMINI 2 (P = .43).

Of the 974 patients randomized in GEMINI 1 and 899 randomized in GEMINI 2, about 85% completed the 3-year trial. Almost all had RRMS (99%) rather than progressing MS. The median age was approximately 36 years, the baseline EDSS score was approximately 1.2, and the median time since diagnosis was about 6.5 years. The mean number of relapses in the prior year was approximately 0.6.

In GEMINI, the secondary outcomes foreshadowed the positive findings in the phase 3 HERCULES trial that came immediately after Dr Oh’s GEMINI trials presentation. The HERCULES trial associated tolebrutinib with a 31% reduction in the risk of confirmed disability progression (CDW) relative to placebo in patients with non-relapsing secondary progressive MS (nrSPMS).

In HERCULES, 1172 patients with nrSPMS were randomized in a 2:1 fashion to tolebrutinib or placebo. For the primary endpoint of CDW at 6 months, tolebrutinib demonstrated a major and highly significant reduction in this primary endpoint (HR, 0.69; P = .00026).

BTKi Disability Protection Supported by Progressive MS Trial

“This is the first trial to show significant slowing of disability in people with nrSPMS,” reported the principal investigator Robert J. Fox, MD, Vice Chair of the Neurological Institute at Cleveland Clinic, Cleveland, Ohio.

For disability improvement at 6 months, tolebrutinib was associated with a nearly 2-fold improvement (HR, 1.88; P =.021). According to both Dr Oh and Dr Fox the results of these two major phase 3 tolebrutinib studies support the principle that the BTKi, which was shown to offer inhibition of relapse comparable to teriflunomide in the GEMINI trials, offers a greater inhibition of chronic inflammation.

“These results are consistent with the hypothesis that acute focal inflammation and smoldering neuroinflammation are two distinct biological processes,” Dr Oh said.

Dr Fox said that the HERCULES results will be submitted to regulatory authorities with the goal of securing an indication for tolebrutinib for nrSPMS.

Both Dr Oh and Dr Fox suggested these results are likely to reorient thinking about the pathophysiology of MS progression and how different processes can be targeted in the future. Other experts agreed.

“I think we are starting to look at different endpoints than ARR, particularly at those that might better reflect progression in later stages of MS and that are independent of ARR,” said Dalia Rotstein, MD, MS researcher and an assistant professor of neurology, University of Toronto, Canada.

A moderator of the ECTRIMS latebreaker session, she suggested that the differences between outcomes of the GEMINI trials and HERCULES trials might have relevance to each other even if the GEMINI trials did not meet their primary endpoint.

Dr Oh reported financial relationships with Amgen, Biogen, Eli Lilly, EMD Serono, Novartis, Roche, and Sanofi, which provided funding for the GEMINI trials. Dr Fox reported financial relationships with more than 15 pharmaceutical companies, including Sanofi, which also provided funding for the HERCULES trial. Dr Rotstein reported financial relationships with Alexion, Biogen, EMD Serono, Horizon, Novartis, Roche, Sanofi, and Touch IME. 

This article originally appeared on MDedge.com, part of the Medscape Professional Network.