Abstract
In the second edition of the Huntington’s Disease Clinical Trials Corner we list all currently registered and ongoing clinical trials, summarise the top-line results of the recently-announced IONIS-HTTRX trial (NCT02519036), expand on Wave Life Sciences’ PRECISION-HD1 (NCT03225833) and PRECISION-HD2 (NCT03225846), and cover one recently finished trial: the FIRST-HD deutetrabenazine trial (NCT01795859).
INTRODUCTION
The Huntington’s Disease Clinical Trials Corner is a regular section devoted to highlighting ongoing and recently completed clinical trials in Huntington’s disease (HD). Clinical trials previously reviewed by the Huntington’s Disease Clinical Trials Corner are listed in Table 1.
Clinical trials previously reviewed by the Huntington’s Disease Clinical Trials Corner
In this edition, we summarise the recently-announced top-line results from the phase 1b/2a IONIS-HTTRX huntingtin-lowering antisense oligonucleotide (ASO) trial (NCT02519036) [1]; highlight the new Wave Life Sciences allele-selective ASO trials, PRECISION-HD1 (NCT03225833) [2] and PRECISION-HD2 (NCT03225846) [3], and summarise the results of the FIRST-HD (NCT01795859) [4, 5] trial of deutetrabenazine.
Finally we tabulate all currently registered and ongoing clinical trials in Tables 2 to 4. For further details on the methodology used please refer to the September 2017 edition of Huntington’s Disease Clinical Trials Corner [6].
Ongoing pharmacological clinical trials registered at the World Health Organization (WHO) International Clinical Trials Research Platform (ICTRP) for people with Huntington’s disease (HD). N/S, not specified; PD, Parkinson’s disease; VMAT2, Vesicular Monoamine Transporter 2. New trials since the last Clinical Trials Corner are indicated by*
Ongoing invasive non-pharmacological clinical trials registered at the World Health Organization (WHO) International Clinical Trials Research Platform (ICTRP) for people with Huntington’s disease (HD). AD, Alzheimer’s disease, CBD; Corticobasal Degeneration; DBS, deep brain stimulation; ET, Essential Tremor; GP, Globus pallidus; HT, Holmes Tremor; MNC, mononuclear cells; MS, Multiple Sclerosis; PD, Parkinson’s disease; TD, Tardive dyskinesia; WD, Wilson’s disease. New trials since the last Clinical Trials Corner are indicated by*
Ongoing non-invasive non-pharmacological clinical trials registered at the World Health Organization (WHO) International Clinical Trials Research Platform (ICTRP) for people with Huntington’s disease (HD). AD, Alzheimer’s disease; ALS, Amyotrophic Lateral Sclerosis; ET, Essential Tremor; HT, Holmes Tremor; MS, Multiple Sclerosis; PD, Parkinson’s disease; TD, Tardive dyskinesia. New trials since the last Clinical Trials Corner are indicated by*
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BREAKING NEWS
December 11th 2017 saw the initial announcement of top-line results from the first-in-human phase 1b/2a trial of IONIS-HTTRX, the first ASO designed to lower huntingtin protein (HTT) to be tested in people with HD (NCT02519036) [1]. The announcement came in the form of a press release from the sponsor, Ionis Pharmaceuticals [7], and was followed by substantial media coverage [8, 9]. As we detailed in the previous Clinical Trials Corner [6], the trial had safety as its primary endpoint. Encouragingly, the release reported that “the safety and tolerability profile ... supports continued development”. More excitingly, dose-dependent reductions in cerebrospinal fluid mutant huntingtin concentration were seen in patients who received IONIS-HTTRx. C. Frank Bennett, Ionis’ Senior Vice President of Research, noted that the mutant huntingtin reduction “substantially exceeded our expectations”. As a result, Roche has exercised its option to license the drug and will now be responsible for future development of the program. In a separate statement for the HD community, Ionis confirmed that an efficacy trial was planned and that “future studies for the program will be conducted globally, including in the US” [10]. Meanwhile, an open-label extension is underway for the 46 participants who took part in the original study (Table 2, NCT03342053) [11].
This is a significant positive announcement in a therapeutic program with substantial promise for disease-modification in HD. Naturally, it will need to be supported by release of more detailed data from the trial, and peer-reviewed publication of the results. The sponsor has committed to supplying these updates in the first half of 2018 [10].
ONGOING CLINICAL TRIALS
A list of all ongoing clinical trials is given in Tables 2, 3 and 4.
PRECISION-HD1 (NCT03225833) and PRECISION-HD2 (NCT03225846)
These trials are phase 1b/2a, multi-centre, international, randomized, placebo controlled, double-blind, parallel studies. They have a combined single ascending dose/multiple ascending dose design, comprising four cohorts of progressively higher ASO doses. In each cohort, participants will be allocated to receive a single dosage or three dosages of the ASO or a placebo. Each trial has the recruitment target of 48 participants; currently recruitment is open in Canada and Poland. The WVE-120101 and WVE-120102 compounds are ASOs targeting the pre-mRNA transcript of two allelic variants linked to the expanded CAG repeat tract in the
The primary outcome is safety and tolerability at 210 days. The secondary outcomes involve pharmacokinetic measurements in plasma; pharmacodynamic measures in cerebrospinal fluid, including mutant huntingtin; and the UHDRS TFC.
While the molecule tested in the IONIS-HTTRx trial and its open-label extension (
However, it is also worth noting that no safety concerns have so far been identified in the ongoing, allele-nonselective IONIS-HTTRx programme [6].
Wave’s platform is also distinguished by the ability to specify the chirality of each phosphorothioate bond in the ASO backbone, which has the potential to improve characteristics such as stability and target mRNA degradation [15]. Each approach – both in terms of chiral purity and allele-selectivity – has potential advantages and disadvantages [12]. Each SNP-selective compound will have to go through independent testing and approval; the testing process to establish suitability is novel and time-consuming; and some mutation-carriers will be ineligible by virtue of possessing no suitable SNPs.
Together, the Wave and IONIS platforms will be informative and provide safety and efficacy information relating to different HTT lowering approaches.
COMPLETED CLINICAL TRIALS
FIRST-HD (NCT01795859)
This trial was a phase 3, multi-centre, international, randomized, placebo controlled, double blind, parallel study. It recruited 90 participants from Canada and the United States. Participant involvement lasted for 13 weeks.
The primary outcome was change from baseline in the UHDRS TMC at weeks 9 and 12. The UHDRS TMC is a subscore of UHDRS total motor score (TMS) that only includes the chorea-related items, and ranges from 0 to 28. The secondary outcomes were the Patient Global Impression of Change (PGIC), the Clinician Global Impression Change (CGIC), the Short Form 36 Health Survey (SF-36), the Berg Balance Test (BBT), and adverse events.
In April 2017, the FDA approved this drug for the treatment of chorea associated with HD. Like tetrabenazine, its label includes a contraindication for patients who are suicidal, or who have untreated or inadequately treated depression.
Deutetrabenazine is a modified version of tetrabenazine containing deuterium (i.e. a stable isotope of hydrogen with mass number of 2) in strategic positions. This modification is intended to provide better pharmacokinetic properties (i.e. slower enzymatic degradation) to this otherwise chemically-identical compound, due to stronger bonds between carbon and deuterium.
Still, little is known about how deutetrabenazine compares with tetrabenazine, an older VMAT2 inhibitor also approved by FDA. In ARC-HD–a multicentre, international, single arm, open label study – the Huntington Study Group explored the safety of switching overnight from a stable and efficacious dosage of tetrabenazine to deutetrabenazine (NCT01897896) [17]. In a preliminary report, about 50% of the sample had at least one adverse event, but the drug was well tolerated with low rates of neuropsychiatric adverse events [18].
Unfortunately no head-to-head blinded comparison has been made between these compounds or is planned. Indirect treatment comparisons showed no apparent efficacy difference [19]. The safety results are contradictory [19, 20], possibly due to a statistical artefact [21]. Overall these results call for close post-licensing surveillance to guide informed prescribing decisions.
CONFLICTS OF INTEREST
FBR and EJW are sub-investigators on LEGATO-HD (NCT02215616), IONIS HTTRx (NCT02519036) and IONIS HTTRx OLE (NCT03342053), and EJW was a sub-investigator on the Amaryllis study (NCT02197130). The authors did not make use of confidential or privileged information: all materials included in this manuscript were collected from publicly available sources. EJW has participated in scientific advisory boards with Hoffmann-La Roche Ltd, Ionis, Shire, GSK and Wave Life Sciences. All honoraria were paid through UCL Consultants Ltd, a wholly owned subsidiary of UCL. Their Host Institution, University College London Hospitals NHS Foundation Trust, has received funds as compensation for conducting clinical trials for Ionis Pharmaceuticals, Pfizer and Teva Pharmaceuticals.
Footnotes
ACKNOWLEDGMENTS
The authors are supported by CHDI Foundation, Inc. (salary support to FBR for conduct of the HDClarity study) and Medical Research Council UK (salary support to EJW).
