Accelerated approval of Oxbryta® (voxelotor): A case study on novel endpoint selection in sickle cell disease.

Sickle cell disease (SCD) is an inherited disease characterized by hemolysis, anemia, and vaso-occlusion leading to substantial morbidity and mortality. Development of prior pharmacologic therapies exclusively utilized vaso-occlusive crisis (VOC) as a clinical efficacy endpoint; however, this focus on VOC did not capture the full extent of disease symptomatology and complications and slowed the development of new therapies. Voxelotor, a hemoglobin S polymerization inhibitor, was recently approved in the United States for the treatment of SCD in adults and adolescents 12 years of age and older through an accelerated approval pathway. The rapid approval and availability of voxelotor was facilitated in a collaborative effort with the US Food and Drug Administration (FDA), using hemoglobin, a biologic surrogate endpoint, as reasonably likely to predict clinical benefit. Use of this new endpoint was supported by FDA-led multistakeholder discussions with physician and patient communities to identify unmet needs and potential clinical trial endpoints, as well as by a company-sponsored analysis of external patient-level data to demonstrate a correlation between hemoglobin change and stroke risk. A two-part phase 3 study was used to allow for rank ordering of key secondary endpoints based on a planned interim analysis. Continued open communication with the FDA was essential to gain agreement on hemoglobin as a novel endpoint and to address the unmet and urgent need of new therapies for SCD.

Randomized, Placebo- and Active-Controlled Crossover Study of the Safety and Efficacy of THVD-102, a Fixed-dose Combination of Oxybutynin and Pilocarpine, in Subjects With Primary Focal Hyperhidrosis.

BACKGROUND: While muscarinic antagonists (anticholinergics) have shown efficacy in treating primary focal hyperhidrosis (PFH), side effects - most commonly dry mouth - are intolerable for most patients. THVD-102, a fixed-dose combination product has been developed combining oxybutynin, a muscarinic antagonist, and pilocarpine, a muscarinic agonist. The pilocarpine is at a dose level and release profile optimized to correct salivary flow impaired by oxybutynin yet not interfere with the therapeutic muscarinic antagonist effect of oxybutynin upon the sweat glands. OBJECTIVES: This study evaluated safety, efficacy, dry mouth and quality of life with THVD-102 (oxybutynin 7.5 mg / pilocarpine 7.5 mg) in subjects with axillary and / or palmar PFH. METHODS: After a 21-day open label treatment period with oxybutynin 5 mg twice daily to determine susceptibility of subjects to develop dry mouth, eligible subjects were randomized to 1 of 6 sequences of 3 study treatments (THVD-102, oxybutynin 7.5 mg, and placebo) in sequential 21day double-blind crossover treatment periods, each preceded by a washout period of at least 7 days. RESULTS: A total of 24 subjects were randomized and 19 finished all crossover treatments. Changes from baseline to end of treatment in symptoms associated with PFH were statistically significant for both THVD-102 versus placebo and for oxybutynin versus placebo as assessed by multiple measures. Beneficial trends, not statistically significant, for gravimetric measurements were also observed. There were no statistically significant differences between THVD-102 and oxybutynin in PFH efficacy. Fewer subjects reported moderate to severe dry mouth while receiving THVD-102 compared to oxybutynin and more subjects categorized their dry mouth as none or mild while receiving THVD-102 compared to oxybutynin. Differences in reported dry mouth were statistically significant. CONCLUSION: THVD-102 was generally well-tolerated. Both THVD-102 and oxybutynin 7.5 mg twice daily were effective in treating PFH. THVD-102 was associated with significantly reduced dry mouth compared to oxybutynin. J Drugs Dermatol. 2017;16(2):127-132..