HRS-1893

HRS-1893 is a small-molecule cardiac myosin inhibitor from Shandong Suncadia Medicine, a subsidiary of Jiangsu Hengrui Pharmaceuticals, developed for obstructive hypertrophic cardiomyopathy (HCM) and adjacent indications. The pivotal Phase 3 placebo-controlled trial in obstructive HCM (NCT07021976, n=228) is active, not recruiting, with primary completion listed for September 2026 and full completion for November 2026 [1]. Two Phase 2 studies have reported positive topline results in 2026: NCT06516068 in obstructive HCM (the feeder study for the Phase 3) and NCT06816251 in non-obstructive HCM [2][9][10]. In September 2025, Hengrui licensed ex-China rights to Braveheart Bio for $75M upfront plus up to $1.013B in milestones and royalties, giving the asset a dedicated Western sponsor that filed its S-1 in 2026 [11]. The commercial question has shifted: it is no longer whether a China-first follower can carve out space behind Bristol Myers Squibb's mavacamten (Camzyos) and Cytokinetics' aficamten (Aficamten), it is whether Braveheart's Western program and Hengrui's China-first launch together compound into a credible third entrant in a validated class.

HRS-1893 is a novel compound, not yet approved anywhere. The headline program is Phase 3 in obstructive HCM at n=228, status active_not_recruiting as of the latest ClinicalTrials.gov update, meaning enrollment is closed and the trial is running to its endpoint; primary completion is listed for September 2026 and full completion for November 2026 [1]. The Phase 2 feeder in obstructive HCM (NCT06516068) reported positive topline results in 2026: a complete Valsalva LVOT-G (left-ventricular outflow-tract gradient, the pressure drop across the obstruction) response in 50 to 86 percent of patients depending on dose, with a mean LVEF (left-ventricular ejection fraction) decrease of only 1.8 to 2.7 percent, a tolerability signal that is directly competitive with mavacamten and aficamten [9][11]. The completed Phase 2 in non-obstructive HCM (NCT06816251, n=84) reported positive topline results in 2026 as well: improvements in NT-proBNP and cardiac troponin I (biomarkers of cardiac wall stress and injury), improved diastolic function on echo, better patient-reported symptoms and exercise capacity, and a favorable tolerability profile [10]. A Phase 2 in heart failure with preserved ejection fraction (NCT07269717, n=48) is open [3]. Phase 1 pharmacokinetic, food-effect and tolerability data in healthy volunteers were published in the British Journal of Clinical Pharmacology in 2026 [4]. In September 2025, Hengrui granted Braveheart Bio an exclusive ex-China license (global except mainland China, Hong Kong, Macau, Taiwan) for $65M upfront plus $10M on technology transfer, up to $1.013B in development and commercial milestones, and royalties; Braveheart filed an S-1 in 2026 [11]. No FDA breakthrough, fast-track, or orphan designation has been reported, though a Braveheart-sponsored US IND is the plausible next step given the deal structure. The regulatory path is NMPA-first in China via Hengrui, with Braveheart owning the Western filing. Note the audit history: the therapeutic area is hypertrophic cardiomyopathy, which an upstream normalizer keeps collapsing into 'Heart Failure', a distinct condition.

In HCM, the heart's left ventricle gets thick and stiff, and the muscle contracts too forcefully while relaxing poorly. The underlying biology is sarcomere hyperactivity: myosin, the motor protein that pulls on actin filaments to generate force, forms too many active cross-bridges per heartbeat. Many HCM patients carry mutations in MYH7 (beta-cardiac myosin heavy chain) or MYBPC3 that lock myosin into this hypercontractile state. Open Targets scores MYH7-HCM at 0.895, among the strongest target-disease links in cardiology [5]. Cardiac myosin inhibitors bind myosin and shift it toward the auto-inhibited 'super-relaxed' state, cutting the number of force-generating heads per cycle. The result is less contractility, less outflow-tract obstruction, lower left-ventricular pressure gradients, and improved diastolic filling. This mechanism is validated clinically, not just mechanistically: mavacamten (Camzyos, BMS) hit its primary endpoint in EXPLORER-HCM and was FDA-approved in 2022 [6], and aficamten (Cytokinetics) hit its primary endpoint in SEQUOIA-HCM with a cleaner titration profile [7]. HRS-1893 is a me-too against a de-risked target, not a mechanistic leap.

The pivotal study is NCT07021976, a multicenter, randomized, double-blind, placebo-parallel-controlled Phase 3 trial in obstructive HCM, n=228, sponsored by Shandong Suncadia Medicine [1]. The primary endpoint is listed as 'clinical response rate', which is softer and less standardized than the composite endpoints used by competitors. EXPLORER-HCM used a five-component hierarchical composite that paired KCCQ-OSS (Kansas City Cardiomyopathy Questionnaire Overall Summary Score, a patient-reported quality-of-life measure), NYHA class (New York Heart Association functional class, a 1 to 4 severity grade), peak VO2 (maximum oxygen uptake during exercise, the gold-standard objective measure of cardiac fitness), patient global assessment, and need for septal reduction therapy [6]. SEQUOIA-HCM used peak VO2 change at week 24 as the primary [7]. HRS-1893's pure 'clinical response rate' endpoint, if not pre-specified with cardiopulmonary exercise testing or a validated patient-reported outcome like KCCQ-OSS, lacks the quality-of-life component that regulators and payers in Western markets have come to expect from this class. The n=228 sample is adequate for a drug class where effect sizes on gradient reduction are large, but underpowered relative to EXPLORER-HCM (n=251) and SEQUOIA-HCM (n=282) if the goal is global registration (though Braveheart would run its own Western pivotal). Status 'active_not_recruiting' means the enrollment window closed and the trial is accruing endpoints; primary completion is listed September 2026 and full completion November 2026, so a topline readout within 12 months is plausible [1]. The parallel Phase 2 in HFpEF (NCT07269717, n=48) is small, exploratory, and primarily safety-driven, which is appropriate given that aficamten's HFpEF program is ongoing and the mechanistic case in HFpEF is less established than in HCM [3].

Our model estimates a 15% chance this drug is eventually approved. It starts from the historical base rate for Phase 2 drugs in this area (about 27%), then adjusts using ten facts about the trial and sponsor. What moves the number most: it is helped by a non-randomized design and more secondary endpoints than usual; it is held back by the sponsor's thin or weak approval record and weak or limited earlier-phase results. The other facts land near average for this stage, so they leave the estimate roughly where the base rate put it.

On-mechanism cardiotoxicity is the dominant safety risk. Mavacamten carries a boxed warning for heart failure due to over-inhibition of contractility, requires echocardiographic monitoring under a REMS program (Risk Evaluation and Mitigation Strategy, a mandatory FDA safety protocol requiring prescriber and pharmacy certification plus regular patient monitoring), and is contraindicated with moderate-to-strong CYP2D6 or CYP3A4 inhibitors [8]. Any cardiac myosin inhibitor with a wide therapeutic index problem gets the same label; HRS-1893's Phase 2 obstructive HCM data suggest a mean LVEF (ejection fraction, the percentage of blood the heart pumps out per beat, where a drop below 50% signals the drug is over-suppressing cardiac contractility) decrease of only 1.8 to 2.7 percent, which is competitive with aficamten's profile but needs to be confirmed in the larger Phase 3 population where ejection-fraction tail-risk shows up [9]. Efficacy risk centers on the soft primary endpoint: if 'clinical response rate' is defined loosely, the trial can hit statistical significance but produce a label too thin to drive Western adoption. Execution risk is lower than typical for Phase 3, given the trial is already past enrollment, but data quality from a single-sponsor China-based trial carries extra scrutiny for any FDA conversation. Commercial risk is the clearest headwind outside China. Camzyos generated $602M in 2024, up 141% year over year, and is still ramping [12]; aficamten launched in 2025 with a cleaner titration profile and is taking share. A third-to-market cardiac myosin inhibitor in Western markets needs superior safety, superior convenience, or a price advantage, and the current public data do not clearly show any of these. In China the dynamic is inverted: HRS-1893 would be first-to-NMPA in the class.

Worth watching, elevated by the Braveheart deal. The signal to look for in the near term is the NCT07021976 Phase 3 readout (primary completion September 2026): specifically, the magnitude of LVOT gradient reduction (how much the drug relieves the outflow-tract obstruction), the rate of ejection fraction drops below 50% (how often the drug over-suppresses cardiac pumping), and whether the pre-specified 'clinical response rate' endpoint is defined in a way that will travel to Western regulators. The Hengrui-to-Braveheart ex-China license (September 2025, $75M upfront plus up to $1.013B in milestones plus royalties) is already the licensing event the earlier draft was speculating about; Braveheart filed its S-1 in 2026, which means the Western pivotal strategy will be run by a dedicated US sponsor rather than Hengrui itself [11]. On the China opportunity: estimated HCM prevalence in China is roughly 750,000 patients at a 0.05% population rate, with obstructive HCM (around 70% of cases) representing the near-term addressable pool. Neither mavacamten nor aficamten is NMPA-approved as of this writing, so an NMPA approval would give Hengrui a first-mover position; NRDL (National Reimbursement Drug List) inclusion is the key commercial catalyst to watch after approval and will determine real volume. The HFpEF Phase 2 (NCT07269717) remains the longer-tail optionality: cardiac myosin inhibition in HFpEF is scientifically interesting but unproven, and a positive signal there would reprice the whole program [3]. Check back when the Phase 3 readout posts, when Braveheart's S-1 pricing clarifies the Western value, or when Hengrui's next quarterly update references the asset. The suspicious RxNorm CUI (2670813) and the recurring therapeutic-area regression to 'Heart Failure' in the underlying database are data-hygiene flags worth noting but do not change the clinical picture.