Novel Investigational Drug for PH: DCR-PHXC
DCR-PHXC: Dicerna's most advanced GalXC product candidate
DCR-PHXC utilizes Dicerna’s GalXC technology, a proprietary platform that advances the development of next-generation RNAi-based therapies designed to silence disease-driving genes in the liver. In December 2017, we initiated human dosing in normal health volunteers (NHVs) in a Phase 1 clinical trial of DCR-PHXC, called PHYOX. We have completed dosing of NHVs in the first phase of the trial. We plan to dose the first primary hyperoxaluria patient with DCR-PHXC in the next phase of the PHYOX trial in second quarter of 2018 and expect to have clinical proof-of-concept (POC) data in the second half of 2018. In addition to the active investigational new drug (IND) application with the U.S. FDA, we have active clinical trial applications (CTAs) in the United Kingdom, France and Germany, having received the appropriate regulatory and ethical approvals for the trial in these countries. A CTA has been submitted and is pending approval in the Netherlands. Additionally, we expect to initiate a multi-dose Phase 2/3 study in the first quarter of 2019, pending positive POC data and regulatory approvals.
GalXC enables subcutaneous delivery of RNAi therapies to hepatocytes in the liver and offers several distinct potential benefits, as extensively demonstrated in various animal models. Such benefits could include potent silencing of the lactate dehydrogenase A (LDHA) gene and other genes; highly specific targeting to hepatocytes, sparing other cell types in the body; a long duration of action; and a simple, infrequent dosing regimen.
In patients with PH, the liver over-produces oxalate, a metabolite that can accumulate throughout the body and particularly in the kidneys, often resulting in end-stage renal disease (ESRD) and the need for both kidney and liver transplants.
At the 12th International Workshop, Dicerna presented research findings on LDHA inhibition, which was shown in animal models to reduce oxalate to normal or near-normal levels in PH types 1, 2, and idiopathic PH (IPH). Research from multiple animal models of PH demonstrated how DCR-PHXC inhibits LDHA, which the Company has identified as potentially being a novel therapeutic target in patients with PH. The data highlights included:
- LDHA inhibition reduces oxalate to normal or near-normal levels in PH types 1, 2, and ethylene glycol-induced hyperoxaluria (a model for IPH).
- LDHA reduction has a near-linear correlation with oxalate reduction and offers a minimal metabolic intervention. These benefits of LDHA inhibition may translate into consistent therapeutic activity even in the event of a missed dose. There are numerous case reports of LDHA deficiency naturally occurring in healthy humans, with no reported adverse effects due to deficiency in the liver.
- DCR-PHXC appeared to be well tolerated in these animal studies, with no adverse effects in the liver. Formal animal toxicology studies are ongoing.
PHYOX: DCR-PHXC-101: Phase 1 Clinical Development Program
In order to speed the drug development process, Dicerna developed a novel clinical trial design: the PHYOX study (also known as DCR-PHXC-101) is a Phase 1 single ascending-dose study in normal healthy volunteers (NHVs) and patients with PH. This clinical trial design was selected to rapidly advance DCR-PHXC as Dicerna works to develop a therapy for this devastating disease.
The study is divided into two groups: Group A is a placebo-controlled, single-blind, single-center Phase 1 study in NHVs; Group B is an open-label, multi-center study in patients with PH type 1 (PH1) and PH type 2 (PH2). Dicerna filed a clinical trial application in the UK in the fourth quarter of 2017 and initiated human dosing in a Phase 1 clinical trial of DCR-PHXC in December of 2017. We have completed dosing of NHVs in the first phase of the trial. The Company plans to dose the first patient with PH in the second quarter of 2018 and expects to have clinical proof-of-concept (POC) data in the second half of 2018. We have submitted CTAs in the UK, Germany, and France and have received the appropriate regulatory and ethical approvals. A CTA has been submitted and is pending approval in the Netherlands. Additionally, we expect to initiate a multi-dose Phase 2/3 study in the first quarter of 2019, pending positive POC data and regulatory feedback.
The primary objective for the trial is to evaluate the safety and tolerability of single doses of DCR-PHXC in both groups. Secondary objectives are to characterize the pharmacokinetics of single doses of DCR-PHXC in NHVs and patients with PH, and to evaluate the pharmacodynamic effects of single doses of DCR-PHXC on biochemical markers including, but not limited to, changes in urine oxalate concentrations.