Cytokinetics and Astellas Provide Updates Regarding Collaborative Skeletal Muscle Program
SOUTH SAN FRANCISCO, Calif., and TOKYO,
Spinal Muscular Atrophy (SMA)
- In June, Cytokinetics announced data from a Phase 2 double-blind, randomized, placebo-controlled clinical study in patients with SMA which was designed to determine potential pharmacodynamic effects of a suspension formulation of reldesemtiv following 8 weeks of oral dosing in each of two cohorts of 36 patients with Type II, Type III, or Type IV disease. Secondary objectives were to evaluate the safety, tolerability and pharmacokinetics of reldesemtiv. The study showed statistically significant concentration-dependent increases in changes from baseline in Six Minute Walk Distance (6MWD), a sub-maximal exercise test of aerobic capacity and endurance. The study also showed statistically significant increases for Maximal Expiratory Pressure (MEP), a measure of strength of respiratory muscles. Other assessments, including the Hammersmith Functional Motor Score - Extended, (a functional motor scale that was assessed in the development program that led to the FDA approval of the first therapy for patients with SMA), Revised Upper Limb Module, Timed Up-and-Go, Forced Vital Capacity, and the SMA Health Index (SMA-HI), a patient reported outcome measure (PROM) developed to comply with FDA standards for PROMs, did not demonstrate differences between reldesemtiv versus placebo. Adverse events were similar between groups receiving reldesemtiv and placebo.
- Additional results presented at the 2018 Muscle Study Group Scientific Meeting in Oxford, U.K. showed sustained increases in 6MWD and MEP four weeks after discontinuation of study drug (i.e., Follow-up). The mean increase versus placebo in the change from baseline in 6MWD on 450 mg twice daily was 24.89 m after 8 weeks of treatment (p = 0.0584) and 30.81 m at Follow-up (p = 0.0381). Similarly, the mean increase versus placebo in the change from baseline in MEP on 450 mg twice daily was 13.15 cm H2O after 8 weeks of treatment (p = 0.0298) and 9.47 cm H2O at Follow-up (p = 0.1344).
- A post-hoc analysis also showed that changes from baseline in the 6MWD at 450 mg twice daily were significantly correlated with changes from baseline on certain domains of the SMA-HI intended to reflect improved endurance, especially Fatigue (correlation coefficient [r] = -0.90, p = 0.01) and Activity Participation (r = -0.82, p = 0.05). Of note, decreases in SMA-HI scores reflect reduced disease burden as measured by that PROM; therefore, the negative correlation coefficients indicate that as 6MWD increases, disease burden assessed by that domain of the SMA-HI is reduced.
- Cytokinetics recently convened an expert advisor meeting to discuss the Phase 2 clinical study of reldesemtiv in patients with SMA and received encouraging and constructive feedback as well as recommendations to inform potential next steps.
- Cytokinetics will be seeking a Type C regulatory interaction with the FDA this year regarding the acceptability of 6MWD as an endpoint for a potential registration program for reldesemtiv in patients with SMA.
Amyotrophic Lateral Sclerosis (ALS)
- Cytokinetics is conducting FORTITUDE-ALS (Functional Outcomes in a Randomized Trial of Investigational Treatment with CK-2127107 to Understand Decline in Endpoints – in ALS) which is expected to enroll 445 patients with ALS and is designed to assess the change from baseline on reldesemtiv versus placebo in the percent predicted slow vital capacity (SVC) and other measures of skeletal muscle function after 12 weeks of treatment. Secondary endpoints include the slope of the change from baseline in the mega-score of muscle strength measured by hand held dynamometry (HHD) and handgrip dynamometry; change from baseline in the ALS Functional Rating Scale – Revised (ALSFRS-R); incidence and severity of treatment-emergent adverse events; and plasma concentrations of reldesemtiv at sampled time points in the trial.
- This trial has now enrolled more than 350 patients with ALS and enrollment is expected to be completed in Q4 2018 with results from the clinical trial expected in the first half of 2019.
Chronic Obstructive Pulmonary Disease (COPD)
- Astellas recently completed a Phase 2 clinical trial designed to assess the potential effect of reldesemtiv compared to placebo on exercise tolerance, assessed as change from baseline in Constant Work Rate (CWR) endurance time over two weeks, in approximately 40 patients with COPD. Additionally, the trial assessed other cardiopulmonary and neuromuscular effects and resting spirometry. In addition, the safety, tolerability and pharmacokinetics of reldesemtiv were assessed.
- This trial of reldesemtiv did not meet the primary endpoint and did not demonstrate a statistically significant treatment difference in any of the secondary endpoints. Adverse events were similar between groups receiving reldesemtiv and placebo.
- Astellas has been conducting a Phase 1b clinical trial designed to assess the effect of reldesemtiv versus placebo on skeletal muscle fatigue in approximately 60 subjects who are 70 to 89 years of age and who have limited mobility. Endpoints measured include the change from baseline versus 14 days of treatment in sum of peak torque during isokinetic knee extensions. Additionally, the trial is designed to assess the effects of reldesemtiv on physical performance as well as the safety, tolerability and pharmacokinetics of reldesemtiv.
- An interim analysis of this study was recently conducted, and the Independent Data Monitoring Committee determined that the pre-defined criteria for lack of efficacy of reldesemtiv had been met; Astellas has notified investigators to halt further enrollment in the trial.
Other Research & Development
As recently announced, Cytokinetics and Astellas are advancing a next-generation FSTA into IND-enabling studies, which triggers a
Skeletal muscle contractility is driven by the sarcomere, the fundamental unit of skeletal muscle contraction and a highly ordered cytoskeletal structure composed of several key proteins. Skeletal muscle myosin is the motor protein that converts chemical energy into mechanical force through its interaction with actin. A set of regulatory proteins, which includes tropomyosin and several types of troponin, make the actin-myosin interaction dependent on changes in intracellular calcium levels. Reldesemtiv, a next-generation fast skeletal muscle troponin activator (FSTA) arising from Cytokinetics' skeletal muscle contractility program, slows the rate of calcium release from the regulatory troponin complex of fast skeletal muscle fibers, which sensitizes the sarcomere to calcium, leading to an increase in skeletal muscle contractility. Reldesemtiv has demonstrated pharmacological activity that may lead to new therapeutic options for diseases associated with muscle weakness and fatigue. In non-clinical models of SMA, a skeletal muscle activator has demonstrated increases in submaximal skeletal muscle force and power in response to neuronal input and delays in the onset and reductions in the degree of muscle fatigue. Reldesemtiv has been the subject of five completed Phase 1 clinical trials in healthy volunteers, which evaluated the safety, tolerability, bioavailability, pharmacokinetics and pharmacodynamics of the drug candidate. Mid-stage clinical trials in patients with SMA, COPD and elderly adults with limited mobility have been completed. Cytokinetics is currently conducting a Phase 2 clinical trial in patients with amyotrophic lateral sclerosis (ALS).
About Cytokinetics and Astellas Collaboration
In 2013, Cytokinetics and Astellas formed a partnership focused on the research, development, and potential commercialization of skeletal muscle activators. The primary objective of the collaboration is to advance novel therapies for diseases and medical conditions associated with muscle impairment and weakness. Under the collaboration, Cytokinetics exclusively licensed to Astellas rights to co-develop and potentially co-commercialize reldesemtiv and other FSTAs in non-neuromuscular indications. In 2014, Astellas and Cytokinetics agreed to expand the collaboration to include certain neuromuscular indications, including SMA, for reldesemtiv and other FSTAs and to advance reldesemtiv into Phase 2 clinical development, initially in SMA. Under the agreement as further amended in 2016, Astellas has exclusive rights to co-develop and commercialize reldesemtiv and other FSTAs in non-neuromuscular indications and certain neuromuscular indications (including SMA and ALS) and other novel mechanism skeletal muscle activators in all indications, subject to certain Cytokinetics’ development and commercialization rights; Cytokinetics may co-promote and conduct certain commercial activities in North America and Europe under agreed scenarios.
Cytokinetics is a late-stage biopharmaceutical company focused on discovering, developing and commercializing first-in-class muscle activators as potential treatments for debilitating diseases in which muscle performance is compromised and/or declining. As a leader in muscle biology and the mechanics of muscle performance, the company is developing small molecule drug candidates specifically engineered to increase muscle function and contractility. Cytokinetics is collaborating with
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Source: Cytokinetics, Incorporated