The Efficacy and Safety of a Selective Estrogen Receptor Beta Agonist (LY500307) for Negative Symptoms and Cognitive Impairment Associated With Schizophrenia

Plain-language summary

The primary objectives of this application are to determine if the selective ERβ agonist LY500307, when added to antipsychotic medications, improves negative and/or cognitive symptoms in patients with schizophrenia. The specific hypotheses to be tested are to determine if LY500307 is safe and well tolerated in this population and whether it elicits a sufficient efficacy signal to be advanced for further testing in schizophrenia. A two-stage Phase 1b/Phase 2a adaptive ("drop the inferior dose") experimental design is ongoing that combines three studies (clinical dose optimization, cortical target engagement confirmation and efficacy and safety assessment) into a single clinical trial. Stage 1 was conducted in year 1 and Stage 2 will be conducted in years 2 and 3. The goal of Stage 1 was to identify and advance the highest dose that did not demonstrate a safety signal and had target selectivity as determined by lack of TT suppression. This criteria was fulfilled at both doses, the larger of the two (75 mg/day dose) was advanced to Stage 2. Furthermore, there was no suggestion of ERα receptor activation (i.e., no pattern of TT decreases or feminization AEs) at either dose (25 mg/day and 75 mg/day). A third arm of 150 mg/day was added to Stage 2 for evaluation. Stage 2 results in the following three arms: placebo, 75 mg/day and 150 mg/day. The goals of Stage 2 are to further assess LY500307 doses for safety and target selectivity, confirm cortical target engagement and assess efficacy. Primary Aim 1: To determine if LY500307 demonstrates cortical target engagement as assessed by fMRI/N-back in frontal-parietal regions. Secondary measures of target engagement are fMRI episodic memory, Pseudo-Continuous Arterial Spin Labeling, Mismatch Negativity/evoked response potentials, Auditory Steady State Response, Auditory P300 and Quantitative EEG (QEEG). Primary Aim 2: To determine if LY500307 is superior to placebo for one or more of the primary efficacy endpoints: negative symptoms (Negative Symptom Assessment Scale - 16-item total score), working memory (the composite score for the Letter Number Sequencing and Spatial Span tests) and verbal memory (Hopkins Verbal Learning Test). Primary Aim 3: To determine if LY500307 reduces total testosterone (TT) plasma concentrations, which is indicative of loss of selectivity for ERβ and engagement of ERα, using the following criteria: Decrease in TT plasma concentrations of 50% from baseline in 50% of subjects per arm treated for two consecutive post-randomization values with LY500307 in Stage 1 and Stage 2 of the trial. Primary Aim 4: To assess the safety of LY500307 by determining if there are SAEs, AEs "probably related to study drug," QTc prolongation, TT suppression (50% reduction from baseline) and to evaluate for other safety signals.

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