A research platform, a novel agent
Though HD research in Latin America remains rife with challenges, a number of investigators at the conference talked optimistically about planned and ongoing HD studies in Latin America.
The biggest of these is ENROLL-HD, a long-term global observational study of families with HD that uses a standardized approach to data collection. The platform, launched in 2013, aims to enroll 20,000 participants for yearly (or more frequent) assessment. Data from ENROLL-HD will support a diverse range of studies on everything from biomarkers to genetic modifiers to quality of life measures in HD.
ENROLL-HD has opened study sites in Argentina, Chile, and Colombia, and plans to launch a site near Lima, Peru, that is home to an HD cluster. Venezuela is considered out of reach, at least for now.
In Barranquilla, Claudia Perandones, MD, PhD, a genetics researcher in Argentina who manages ENROLL-HD for Latin America and is a cofounder of Factor-H, explained why the kind of clusters seen in Latin America are so valuable scientifically.
The extended family groups share a disease haplotype, eat the same foods, and live in similar environments, Dr. Perandones noted. Because not all the variation in HD can be explained by the number of CAG repeats a patient has, having a large sample with a common haplotype would help researchers pinpoint other environmental and genetic factors that can modify the onset or progress of the disease.
Another key goal of ENROLL-HD, investigators say, is to speed recruitment into clinical trials as they arise. And for the first time in history, potentially game-changing therapies are being developed specifically for HD.
For the past 5 years the Swiss pharmaceutical giant Roche has worked with a smaller biotech firm, Ionis Pharmaceuticals, on an agent called RG6042, which was known until recently as IONIS-HTTRx. CHDI was extensively involved in the agent’s preclinical development, contributing some $10 million to get it off the ground.
RG6042 is an antisense oligonucleotide, delivered by spinal injection, which works by interrupting an mRNA signaling pathway to suppress production of mutant HTT (mHTT) protein in the brain. Antisense oligonucleotides, sometimes called gene silencing therapies, are a new and promising approach in neurodegenerative diseases. Two have received FDA approval to treat spinal muscular atrophy and Duchenne muscular dystrophy.
In April 2018, Roche announced positive results from phase 1/2a study in 46 HD patients in Europe and North America. Patients in that 13-week study saw significant (up to 60%) dose-dependent reductions of the mHTT in their cerebrospinal fluid; a post hoc analysis also found some evidence of functional improvement (Neurology. 2018;90[15 Supplement]:CT.002).
These encouraging findings led to Roche’s announcement of a global phase 3 randomized, controlled trial that is scheduled to begin enrolling in 2019. Roche hopes to randomize 660 patients with mild HD across 15 countries for the 2-year trial, called GENERATION-HD1.
Sites in Latin America are expected to include Argentina, Chile, and Colombia.
At the Barranquilla meeting, Daniel Ciriano, MD, Roche’s Argentina-based medical director for Latin America, extolled the company’s commitment to ethics and social welfare in the region. In recent years, Roche has increased its humanitarian commitments across Latin America, including helping rebuild a Chilean village after an earthquake and offering free breast cancer and kidney disease treatments.
RG6042 is only one of a number of promising approaches to HD. Other therapies in the pipeline include gene silencing delivered by viral vectors instead of repeated spinal injections, an oral drug that interrupts mHTT production, immunotherapies, and even CRISPR gene–editing techniques.
Little was said at the conference, however, about how Latin American HD communities might be able to afford RG6042 or any other therapy that emerges from the pipeline.
Dr. Muñoz-Sanjuán called the issue “a theme for future discussion.”
“This is an area that has to be handled carefully and not one we are heavily invested in yet, although it’s very important,” he said.