Roche Discontinues Two Huntington's Disease Programs After Tominersen Fails Phase II and RG6496 Hits Preclinical Safety Hurdle
核心洞察
Roche announced the discontinuation of the Phase II GENERATION HD2 trial of tominersen after the antisense oligonucleotide failed to meet clinical efficacy endpoints despite achieving biomarker reductions.
The company also halted the Phase I POINT-HD study of RG6496 (搜索), a mutant-selective huntingtin (搜索)-lowering ASO, after concurrent animal studies revealed it cannot be given chronically with repeated dosing.
In both cases, no new safety concerns were identified in trial participants; Roche emphasized the decisions were independent and data-driven.
Roche has announced the termination of two separate clinical programs for Huntington's disease (搜索) (HD), delivering a significant blow to the HD community. The Swiss pharmaceutical giant disclosed in a community letter that the Phase II GENERATION HD2 trial of tominersen failed to meet its efficacy objectives, while the Phase I POINT-HD study of RG6496 (搜索) was halted after concurrent animal studies raised concerns about long-term dosing feasibility.
The company emphasized that neither decision was related to safety issues in trial participants, and that the two announcements, though simultaneous, were "independent, data-driven events, which have coincided by chance."
Tominersen: Biomarker Promise Fails to Translate into Clinical Benefit
Tominersen, an antisense oligonucleotide (ASO) delivered via spinal tap, was the first drug to demonstrate that lowering huntingtin (搜索) protein is possible in people. The therapy targets both wild-type and expanded huntingtin protein—an approach known as total huntingtin lowering.
The drug's development path has been turbulent. A prior Phase III study, GENERATION HD1, was halted early in 2021 after an independent data review committee determined that safety risks outweighed potential benefits. However, a post hoc analysis suggested that younger individuals with less advanced disease and lower CAG repeat numbers might benefit from a lower or less frequent dose. This finding prompted the launch of GENERATION HD2.
The Phase II, placebo-controlled GENERATION HD2 trial initially tested two doses of tominersen before focusing on a 100 mg dose versus placebo. The study aimed to determine whether tominersen could influence HD biomarkers—including huntingtin (搜索) and neurofilament light (搜索) (NfL), an indicator of brain health—and whether it could slow disease progression as measured by the composite Unified Huntington's Disease (搜索) Rating Scale (cUHDRS) and Total Functional Capacity (TFC).
According to Roche, tominersen did exactly what it was designed to do biologically. Participants receiving the drug showed significant reductions in expanded huntingtin (搜索) protein levels in cerebrospinal fluid (CSF), alongside reductions in NfL in both CSF and blood plasma. Roche reported no new safety concerns during the study.
Despite these encouraging biomarker changes, the clinical endpoints were not met. People receiving tominersen did not experience a slowing of disease progression compared with those receiving placebo over the approximately 16-month study period. The hoped-for improvements in cUHDRS and TFC did not materialize, leading Roche to discontinue development of tominersen entirely. There will be no open-label dosing or compassionate use of the drug.
"This is a complete termination of this drug for testing and treatment of HD by Roche," the company indicated, advising participants to contact their study centers and neurologists for transition planning.
RG6496: Preclinical Safety Findings End Mutant-Selective Approach
Roche also announced the discontinuation of POINT-HD, a first-in-human Phase I study of RG6496 (搜索). This ASO was designed to selectively lower only the expanded copy of the huntingtin (搜索) gene in people carrying a particular SNP—a small DNA variation present in some individuals with HD. Like tominersen, RG6496 was delivered via spinal tap.
The decision to end this program was not based on results from trial participants. POINT-HD had only recently begun enrolling, with just three people receiving a single dose, none of whom experienced adverse side effects.
In parallel with the human study, Roche was conducting longer-term animal studies to assess the safety of repeated dosing. Those concurrent animal studies identified findings that Roche concluded would prevent the drug from being developed as a treatment suitable for long-term administration. While Roche stated there are no major safety concerns for individuals who received a single dose, the company stopped the program because repeated treatment would no longer be possible. Participants already enrolled will continue to receive follow-up monitoring. Detailed information about the animal study findings has not yet been released.
Implications for Huntingtin Lowering
The GENERATION HD2 results raise important questions about the huntingtin (搜索)-lowering hypothesis, but experts caution against overinterpretation. The study suggests that the degree of huntingtin lowering and NfL changes achieved over approximately 16 months may not have been sufficient to meaningfully slow HD progression. However, this does not necessarily mean that huntingtin lowering as a strategy cannot work.
Several open questions remain: whether huntingtin (搜索) lowering was sufficient in the most critical brain regions, whether treatment was started early enough, whether 16 months is adequate to detect changes in a slowly progressing disease, and whether different approaches—such as splice modulators or gene therapy—could produce different results. Notably, uniQure's AMT-130 gene therapy program has suggested that clinical effects may take several years to emerge.
Roche's Ongoing Commitment and Community Contribution
Roche stated that its gene therapy program, RG6662 (formerly developed by Spark Therapeutics), continues unchanged, and the company remains committed to exploring multiple therapeutic approaches for HD. The company has committed to sharing full data from these programs at future medical meetings.
More than 1,500 HD families have contributed to Roche's huntingtin (搜索)-lowering programs since the first tominersen studies began over a decade ago. These studies proved that huntingtin protein can be safely measured and lowered in people, supported the development and validation of biomarkers now used across HD research, and generated knowledge that will influence the design of future therapies.