Safety, pharmacokinetics and target engagement of novel RIPK1 inhibitor SAR443060 (DNL747) for neurodegenerative disorders: Randomized, placebo-controlled, double-blind phase I/Ib studies in healthy subjects and patients

Abstract

RIPK1 is a master regulator of inflammatory signaling and cell death and increased RIPK1 activity is observed in human diseases, including Alzheimer's disease (AD) and amyotrophic lateral sclerosis (ALS). RIPK1 inhibition has been shown to protect against cell death in a range of preclinical cellular and animal models of diseases. SAR443060 (previously DNL747) is a selective, orally bioavailable, central nervous system (CNS)-penetrant, small-molecule, reversible inhibitor of RIPK1. In three early-stage clinical trials in healthy subjects and patients with AD or ALS (NCT03757325 and NCT03757351), SAR443060 distributed into the cerebrospinal fluid (CSF) after oral administration and demonstrated robust peripheral target engagement as measured by a reduction in phosphorylation of RIPK1 at serine 166 (pRIPK1) in human peripheral blood mononuclear cells compared to baseline. RIPK1 inhibition was generally safe and well-tolerated in healthy volunteers and patients with AD or ALS. Taken together, the distribution into the CSF after oral administration, the peripheral proof-of-mechanism, and the safety profile of RIPK1 inhibition to date, suggest that therapeutic modulation of RIPK1 in the CNS is possible, conferring potential therapeutic promise for AD and ALS, as well as other neurodegenerative conditions. However, SAR443060 development was discontinued due to long-term nonclinical toxicology findings, although these nonclinical toxicology signals were not observed in the short duration dosing in any of the three early-stage clinical trials. The dose-limiting toxicities observed for SAR443060 preclinically have not been reported for other RIPK1-inhibitors, suggesting that these toxicities are compound-specific (related to SAR443060) rather than RIPK1 pathway-specific.

Conflict of interest statement

J.Ha., R.T., A.C.H., F.H., V.T., R.E., Y.Z., K.S.L., J.H.N., X.T., M.C., B.F., C.H., and M.T. are employees of and may hold stocks in Denali Therapeutics Inc. R.J.P., M.A.A., M.Z., and N.A. are employees of and may hold stocks in Sanofi (Genzyme). All other authors declared no competing interests for this work.

© 2022 The Authors. Clinical and Translational Science published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.

Figures

FIGURE 1

SAR443060 inhibition of RIPK1 serine 166 autophosphorylation in human PBMCs. Human peripheral blood mononuclear cell (PBMCs) from four healthy donors were thawed and resuspended in Roswell Park Memorial Institute (RPMI) complete medium. Cells were incubated with a range of concentrations of SAR443060 and then stimulated with a combination of TNF‐α, SM‐164, and zVAD‐FMK (TSZ). Two hours later, cells were lysed, and phosphorylated receptor‐interacting serine/threonine‐protein kinase (pRIPK1) was detected by a plate‐based immunoassay on the Meso Scale Discovery (MSD) platform. Increasing concentrations of SAR443060 (3.8 pM–4 μM) reduced the phosphorylation of RIPK1 at Ser166 in stimulated human PBMCs in a concentration‐dependent manner with a geometric mean 50% maximum inhibitory concentration (IC50) value of 3.9 nM. Sample dose–response curve is from one donor. At each concentration tested, the mean and SD of the pS166 RIPK1 signal were calculated from the technical duplicate. Error bars are SDs.

FIGURE 2

Study designs, randomization, and analysis populations for the completed SAR443060 phase I and phase 1b clinical program. (a) Phase I FIH study in healthy volunteers. (b) Phase Ib studies in patients with AD or ALS. Footnotes: a. (1) One subject was withdrawn during the study (cohort A2 after completion of period 1), due to a medical history of eczema which made the subject ineligible for the study. b. (1) One patient discontinued during administration of placebo in period 2 of the AD study due to disease progression and was not included in the PD analysis. (2) The first patient in the ALS study was enrolled at the original dose of 200 mg b.i.d. and completed 21 days in the first treatment period. This patient decided to forgo the rest of treatment period 1 without withdrawing from the study, and subsequently completed the treatment period 2 and the follow‐up visits. (3) One patient in the ALS study discontinued during administration of placebo in period 2 due to disease progression. (4) One patient in the ALS study was excluded from the PD and PK analysis as this patient had stopped taking edaravone 9 days prior to administration of SAR443060 in period 1 (protocol deviation). (5) Two subjects withdrew from the ALS OLE study prematurely due to disease progression. (6) For the ALS OLE study, the coronavirus disease 2019 (COVID‐19) pandemic prevented the pre‐planned collection of several CSF and blood samples from patients. Furthermore, the OLE study was terminated early by the sponsor’s decision. As a result, there was not enough PK and PD data from the OLE available for analysis. AD, Alzheimer’s disease; ALS, amyotrophic lateral sclerosis; ALSFRS‐R, Amyotrophic Lateral Sclerosis Functional Rating Scale‐Revised; CSF, cerebrospinal fluid; DB, double‐blind; FIH, first‐in‐human; MAD, multiple ascending dose; MDS, micronized drug substance; OLE, open‐label extension; PBMC, peripheral blood mononuclear cell; PD, pharmacodynamic; PK, pharmacokinetic; pSer166‐RIPK1, phosphorylation at serine 166 on receptor‐interacting serine/threonine‐protein kinase 1; SAD, single ascending dose; SDN, spray‐dried nanosuspension.

FIGURE 3

SAR443060 geometric mean plasma concentration–time profiles in healthy subjects. (a) After administration of a single dose of the SDN and MDS formulations in fasted conditions and after a high‐fat breakfast on a semi‐logarithmic scale. (b) Day 1 and day 14 overlay for administration of twice‐daily dosing (b.i.d.) on a semi‐logarithmic scale. (c) Day 1 and day 14 full PK plasma concentration–time profiles and days 4, 7, and 11 predose (trough) concentrations during administration of twice‐daily dosing (b.i.d.) on a semi‐logarithmic scale. Mean (±SD) PK plasma concentration–time profiles on a linear scale per cohort are available in Figure S1. MDS, micronized drug substance; PK, pharmacokinetic; SDN, spray‐dried nanosuspension.

FIGURE 4

Median percentage of pRIPK1 inhibition compared to baseline after SAR443060 and placebo administration in healthy subjects. (a) After single ascending doses and placebo up to 48 h postdose. (b) After ascending b.i.d. doses and placebo up to 48 h post the last dose on day 14. Error bars represent interquartile range (IQR). X‐axis states the study days (D) and hours (HR) for each sampling timepoint. D1.0HR represents predose (baseline) measurement and D1.2HR the first measurement 2 h postdose on day 1. Timepoints on the X‐axis are not equally spaced in time. MDS, micronized drug substance; SDN, spray‐dried nanosuspension.

FIGURE 5

Median percentage of pRIPK1 inhibition compared to baseline after SAR443060 and placebo administration in patients with AD (a) or ALS (b). SAR443060 50 mg or matching placebo was administered approximately every 12 h (b.i.d.) in each treatment period for 28 days, followed by a final morning dose on the 29th day. Error bars represent interquartile range (IQR). D01.00HR represents predose (baseline) measurement and D01.02HR the first measurement 2 h postdose on day 1. Timepoints on the X‐axis are not equally spaced in time. AD, Alzheimer’s disease; ALS, amyotrophic lateral sclerosis.