Emixustat Hydrochloride for Geographic Atrophy Secondary to Age-Related Macular Degeneration: A Randomized Clinical Trial

PURPOSE

To determine whether emixustat hydrochloride (emixustat) reduces the rate of enlargement of geographic atrophy (GA) compared with placebo in subjects with age-related macular degeneration (AMD) and to evaluate the safety and tolerability of emixustat over 24 months of treatment.

DESIGN

Multicenter, randomized, double-masked, placebo-controlled, phase 2b/3 clinical trial.

PARTICIPANTS

Patients with GA secondary to AMD, a visual acuity score of at least 35 letters, and GA with a total area of 1.25 to 18 mm² were enrolled.

METHODS

Subjects were randomized (1:1:1:1) to emixustat 2.5 mg, 5 mg, 10 mg, or placebo, administered orally once daily for 24 months. Visits included screening, baseline, and months 1, 2, 3, 6, 9, 12, 15, 18, 21, 24, and 25.

MAIN OUTCOME MEASURES

The primary efficacy end point was the mean annual growth rate of total GA area in the study eye, as measured by a central reading center using fundus autofluorescence (FAF) images. The change from baseline in normal luminance best-corrected visual acuity (NL-BCVA) was a secondary efficacy end point.

RESULTS

Of 508 randomized subjects, 320 completed the study. Demographics and baseline characteristics were comparable between treatment groups. On average, GA lesions in the study eye grew at a similar rate in each group (emixustat: 1.69 to 1.84 mm²/year; placebo: 1.69 mm²/year; P ≥ 0.81). Changes in NL-BCVA were also comparable between groups. Subjects with a larger low luminance deficit (LLD) at baseline (≥20 letters) demonstrated a more rapid growth of GA over 24 months. No relationship was observed between the risk-allele status of the AMD-associated single-nucleotide polymorphisms tested and the growth rate of GA. The most common adverse events in emixustat-treated subjects were delayed dark adaptation (55%), chromatopsia (18%), visual impairment (15%), and erythropsia (15%).

CONCLUSIONS

Emixustat did not reduce the growth rate of GA in AMD. The most common adverse events were ocular in nature and likely related to the drug's mechanism of action. Data gained from this study over a 2-year period add to the understanding of the natural history of GA and the baseline characteristics affecting the growth rate of GA.

The Water Dipole Moment in Water Clusters

The average dipole moment of a water molecule in the condensed phase is enhanced by around 40 percent relative to that of an isolated monomer. This enhancement results from the large polarization caused by the electric field induced by surrounding monomers. A quantitative molecular description of this polarization is essential for modeling aqueous solvation phenomena. This combined theoretical and experimental study of dipole moments in small water clusters provides such a description and also gives insights into the structure of liquid water.

Retinoid effects in purified cultures of chick embryo retina neurons and photoreceptors

PURPOSE

To investigate the effects of retinoic acid, retinol, and 11-cis retinaldehyde on proliferation, differentiation, and survival of cultured embryonic chick neural retina cells; to describe the metabolic transformations of these retinoids by the cultured cells.

METHODS

Retinoids were added to glia-free, low-density cultures of neural retina cells, which underwent subsequent examination to determine the numbers of neurons and photoreceptors that differentiated and survived under differing conditions. Cells and conditioned medium were extracted to identify and quantify retinoid metabolic products by high pressure liquid chromatography.

RESULTS

Retinoid treatment resulted in dose-dependent increases in the number of differentiated photoreceptors present in the cultures after 6 days; smaller increases in nonphotoreceptor neurons were also observed. Retinoids were more effective when added at culture onset than at later times, but they did not stimulate cell proliferation. The order of potency was retinol > 11-cis retinaldehyde > retinoic acid. Exogenous retinoic acid was recovered unmodified after a 24-hr incubation period; retinol was also stable and unmetabolized, except for the formation of a small quantity of retinyl acetate. 11-cis retinaldehyde was less stable, and was metabolized into both retinoic acid and retinol.

CONCLUSIONS

Retinol, 11-cis retinaldehyde, and retinoic acid can promote the survival (and possibly differentiation) of cultured embryonic retina neurons and photoreceptors in the absence of glia and retinal pigment epithelium. Although retinoic acid is likely to function by interacting with one of the known nuclear receptors for this retinoid, the effectiveness of retinol in the absence of metabolic transformation into retinoic acid suggests the possible existence of a distinct, yet undiscovered receptor.

Lymphocyte surface components. I. Stimulation of enzyme-treated rabbit lymphocytes by non-specific mitogens

Rabbit lymphocytes from various locations were treated briefly with proteases and the rate of incorporation of thymidine following stimulation by `non-specific' stimulants (Staphylococcus filtrate, SF, and Phaseolus vulgaris phytohaemagglutinin, PHA) measured. The proteases themselves, especially at concentrations exceeding 0·005%, sometimes caused cells to incorporate more thymidine than untreated cells. Stimulation with SF or PHA was much greater when lymphocytes were first treated with protease at low concentrations (when enzyme alone failed to stimulate). This effect was shown particularly by lymphocytes from gut-associated lymphoid organs. Peripheral blood lymphocytes, while unaffected by proteases at a concentration of 0·005%, incorporated increased amounts of thymidine after treatment with proteases at higher concentrations: pronase is especially potent. Further evidence is presented, distinguishing between the cytoagglutinating and mitogenic characters of PHA.