Acasti Pharma (ACST) Reports Positive Results for Pharmacokinetic Bridging Study, With Intravenous GTX-104 Meeting All Endpoints

Acasti Pharma Inc. (Nasdaq: ACST) announced today that the top line results of its pharmacokinetic (PK) bridging study with IV GTX-104, the Company’s lead drug candidate for the treatment of Subarachnoid Hemorrhage (SAH), met all its planned study endpoints. The primary objective of the study was to evaluate the relative bioavailability of IV GTX-104 compared to oral nimodipine in healthy adult male and female subjects, while the secondary objective was to assess its safety and tolerability. The Company plans to submit these results to the US Food and Drug Administration (FDA), along with its proposed study design for the Phase 3 safety study which is on track to start in the second half of 2022. The safety study is expected to be the final step required to seek regulatory approval under the 505(b)(2) regulatory pathway before submitting a New Drug Application to the FDA.

SAH affects about 50,000 patients per year in the U.S. and represents an estimated total addressable market of more than $300 million in the US alone (Becske, 2016; NINDS, 2016; and Connolly, 2012). There are an estimated additional 55,000 patients in Europe. Based on the improved bioavailability, more convenient and consistent mode of administration, safety and tolerability, management believes GTX-104 has the potential to capture a significant share of the SAH market.

"We are very pleased to report the top line results for this important PK study which met all its planned study endpoints,” commented Jan D’Alvise, Acasti’s CEO. “The study completed on schedule, and we are now working with our clinical and regulatory advisors to finalize our study design and protocol for the Phase 3 safety study of GTX-104. We believe the safety study should be relatively low risk based on the favorable safety profile observed in more than 130 patients combined from this PK study and a previous PK study. We plan to submit the protocol along with our PK data to the FDA to confirm the final steps required prior to registration. Based on the improved bioavailability demonstrated in this study, we continue to believe GTX-104 delivered intravenously has the potential to be a more convenient, efficient and controlled way to deliver nimodipine to patients with SAH.

“As observed in a previous PK study with GTX-104 and now with the results of this study, the inter- and intra-subject variability was also much lower for GTX-104 as compared with oral nimodipine,” D’Alvise continued. “Importantly, because of its better absorption profile and more consistent blood levels, GTX-104 may provide physicians with a more reliable and effective treatment for patients with SAH. This is a key advantage, as we believe GTX-104 could help to reduce the incidence of hypotensive events and vasospasm, which require immediate and costly intervention and can lead to worse outcomes for the patient. Moreover, it could provide dosing flexibility and a more consistent and convenient route of administration for the significant percentage of patients who present and remain unconscious during their ICU stay following SAH. For these reasons, we believe GTX-104 could be well-positioned to rapidly capture market share if the FDA grants approval.”

The PK study was completed at a single center in Canada and followed a 2-period crossover design where each subject received IV GTX-104 first, followed by oral nimodipine; or oral nimodipine first, followed by IV GTX-104. Fifty-eight subjects were randomized in a ratio of 1:1 between IV GTX-104 first or oral nimodipine first. IV GTX-104 and oral nimodipine was administered to all subjects over a period of 72 hours. A total of 56 and 55 subjects were included in the PK analysis at Day 1 and Day 3, respectively, as two subjects did not complete one of the two periods and one subject was excluded due to a protocol deviation, as prospectively defined in the statistical analysis plan (SAP).

The primary PK endpoints were maximum concentration (expressed as Cmax) during the first 4 hours on Day 1 and the total amount of nimodipine in the blood (expressed as the area under the curve (AUCDay 3, 0-24hr)) on Day 3. The secondary endpoint was Cmax measured over 24 hours on Day 3. The ratio of IV/oral is presented below for each endpoint with the corresponding 90% confidence interval (CI). A ratio of 1 indicates no absolute difference between IV GTX-104 and oral nimodipine.

The IV/oral ratio (%) and its corresponding 90% CI (range) for the primary and secondary endpoints in the subjects who completed each treatment period were as follows:

All three endpoints indicated that statistically there was no difference in exposures between IV GTX-104 and oral nimodipine over the defined time periods for both maximum exposure and total exposure. Plasma concentrations obtained following IV administration showed significantly less variability between subjects as compared to oral administration of capsules, since IV administration is not as sensitive to some of the physiological processes that affect oral administration, such as taking the drug with and without meals, variable GI transit time, variable drug uptake from the GI tract into the systemic circulation, and variable hepatic blood flow and hepatic first pass metabolism. Previous studies have shown these processes significantly affect the oral bioavailability of nimodipine, and therefore cause oral administration to be prone to larger within and between-subject variability.

The bioavailability of oral nimodipine capsules observed was only 8% compared to IV GTX-104. Consequently, less than one-tenth the amount of nimodipine is delivered with GTX-104 to achieve the same blood levels as with the oral capsules. In addition, the diurnal variation associated with IV GTX-104 was approximately half of that seen with the oral nimodipine capsules. Diurnal variation takes into consideration variation in body functions (blood flow, renal function and hepatic metabolism) over the course of a day.

No serious adverse events (AEs) and no AEs leading to withdrawal were reported during the study. More gastro-intestinal disorders were observed with oral nimodipine (16% vs 7% for IV GTX-104), and as expected in the context of a phase I trial conducted in healthy volunteers, more administration and sampling site related events were observed with IV GTX-104 (41% vs 11% for oral nimodipine). The other most frequently observed AEs (IV/oral) were headache (36%/36%), somnolence (9%/13%) and hot flashes/flushing (10%/11%).

Cash UpdateAcasti also reports that it had $43.7M cash on hand as of March 31, 2022, which management continues to expect will fund lead drug candidate GTX-104 through NDA submission, and GTX-102 for ataxia telangiectasia and GTX-101 for postherpetic neuralgia to additional key milestones.

Conference call

Acasti will host a conference call on Wednesday, May 18, 2022 at 1:00 PM Eastern Time to discuss the results of the trial. The conference call will be available via telephone by dialing toll free 888-506-0062 for U.S. callers or +1 973-528-0011 for international callers and using entry code 456498. A webcast of the call may be accessed at https://www.webcaster4.com/Webcast/Page/2210/45556 or on the Company’s Investor Relations section of the website: https://www.acastipharma.com/investors/.

A webcast replay will be available on the Company’s Investors News/Events section of the website (https://www.acastipharma.com/investors/) through May 18, 2023. A telephone replay of the call will be available approximately one hour following the call, through May 25, 2022, and can be accessed by dialing 877-481-4010 for U.S. callers or +1 919-882-2331 for international callers and entering conference ID: 45556.

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