A Free Base Oxazine Derivative in Crystalline Form

#The present invention relates to a specific solid form of N-(6-((3R,6R)-5-amino-3,6-dimethyl-6-(trifluoromethyl)-3,6-dihydro-2H-1,4-oxazin-3-yl)-5-fluoropyridin-2-yl)-3-chloro-5-(trifluoromethyl)picolinamide, namely Form A. The present invention further discloses the process for preparing said solid form, pharmaceutical compositions comprising said solid form, and methods of using said solid form and pharmaceutical compositions in the treatment or prevention of Alzheimer's disease or cerebral amyloid angiopathy.

#Alzheimer's disease (AD) is one of the most prevalent neurological disorders worldwide and the most common and debilitating age-related condition, causing progressive amnesia, dementia, and ultimately global cognitive failure and death. Currently, the only pharmacological therapies available are symptomatic drugs such as cholinesterase inhibitors or other drugs used to control the secondary behavioural symptoms of AD. Investigational treatments targeting the AD pathogenic cascade include those intended to interfere with the production, accumulation, or toxic sequelae of amyloid-β (Aβ) species (Kramp V P, Herrling P, 2011). Strategies that target decreasing Aβ by: (1) enhancing the amyloid clearance with an active or passive immunotherapy against Aβ; (2) decreasing production through inhibition of Beta-site-APP cleaving enzyme-1 (BACE-1, an enzyme involved in the processing of the amyloid precursor protein [APP]), are of potential therapeutic value. No effective disease-modifying treatment of AD has yet been described in the literature.

#Cerebral amyloid angiopathy (CAA) is a common age related cerebral small vessel disease, characterised by progressive deposition of amyloid-β (Aβ), in particular Aβ40, in the wall of small to medium sized arteries, arterioles and capillaries of the cerebral cortex and overlying leptomeninges (Charidimou A et al., 2011). CAA often coexists with Alzheimer's disease (AD). Mild forms of CAA often appear asymptomatic; however, CAA may also lead to severe vascular pathologies and is a risk factor for cerebral hemorrhages ranging from silent microbleeds to spontaneous intracerebral haemorrhage, a devastating form of stroke.

#FIG. 1 shows the X-ray powder diffraction pattern for unmicronized crystalline Form A of the Compound of Formula 1 when measured using CuKα radiation.

#FIG. 2 shows the DSC thermogram for unmicronized crystalline Form A.

#FIG. 3 shows the X-ray powder diffraction pattern for micronized crystalline Form A of the Compound of Formula 1 when measured using CuKα radiation.

#The present invention provides a polymorphic form of N-(6-((3R,6R)-5-amino-3,6-dimethyl-6-(trifluoromethyl)-3,6-dihydro-2H-1,4-oxazin-3-yl)-5-fluoropyridin-2-yl)-3-chloro-5-(trifluoromethyl)picolinamide, which is Form A. N-(6-((3R,6R)-5-amino-3,6-dimethyl-6-(trifluoromethyl)-3,6-dihydro-2H-1,4-oxazin-3-yl)-5-fluoropyridin-2-yl)-3-chloro-5-(trifluoromethyl)picolinamide, also referred to as the “Compound of Formula 1” or “Compound 1”, was originally described in WO 2012/095469 A1, Example 34. WO 2012/095469 A1 is incorporated herewith by reference in its entirety, in particular the disclosure related to the synthesis of Example 34.

#As described herein, the free base of Compound 1 can be a crystalline form that exists as one or more polymorph forms, including hydrate forms. These polymorph forms (alternatively known in the art as polymorphic forms or crystal forms) differ with respect to their X-ray powder diffraction patterns, spectroscopic, physicochemical and pharmacokinetic properties, as well as their thermodynamic stability.

#It is desirable to have access to different polymorphic forms of Compound 1 for several reasons. Distinct polymorph forms may exhibit different physical properties such as melting point, hygroscopicity, solubility, flow properties or thermodynamic stability, and therefore, distinct polymorph forms allow the choice of the most suitable form for a given use or aspect, for example, in distinct administration forms such as capsules, or in the manufacture of a drug form having optimum pharmacokinetic properties.