A crystalline form of compound, wherein said compound is in the form of an L-tartrate salt or a pharmaceutically acceptable solvate thereof, which is characterized by: (i) an x-ray powder diffraction pattern having two or more diffraction peaks at 2[theta] values selected from 6.67 ± 0.2, 8.237± 0.2, 9.777 ± 0.2, 11.96 ± 0.2, 12.38 ± 0.2, 13.06 ± 0.2, 13.38 ± 0.2, 13.94 ± 0.2, 14.90 ± 0.2, 15.40 ± 0.2, 15.95 ± 0.2, 16.27 ± 0.2, 16.54 ± 0.2, 17.36 ± 0.2, 17.57 ± 0.2, 17.86 ± 0.2, 19.64 ± 0.2, 19.86 ± 0.2, 20.12 ± 0.2, 20.73 ± 0.2, 21.14 ± 0.2, 21.58 ± 0.2, 22.57 ± 0.2, 22.95 ± 0.2, 23.29 ± 0.2, 23.57 ± 0.2, 24.07 ± 0.2, 24.63 ± 0.2, 25.30 ± 0.2, 26.38 ± 0.2, 27.09 ± 0.2, 27.67 ± 0.2, 27.97 ± 0.2, 28.91 ± 0.2, 29.28 ± 0.2, 30.08 ± 0.2, 30.41 ± 0.2, 31.90 ± 0.2 and 34.49 ± 0.2, when using Cu Kα radiation and a scan speed of 0.146°/s (Form E), more preferably having two or more diffraction peaks at 2[theta] values selected from 6.67 ± 0.2, 13.06 ± 0.2, 13.38 ± 0.2, 14.90 ± 0.2, 17.36 ± 0.2, 17.57 ± 0.2, 19.64 ± 0.2, 20.73 ± 0.2, 23.57 ± 0.2 and 25.30 ± 0.2 (Form E); or (ii) a differential scanning calorimetry trace recorded at a heating rate of 20°C per minute which shows a maximum endothermic peak at a temperature between 176°C and 185°C; or (iii) an x-ray powder diffraction pattern having two or more diffraction peaks at 2[theta] values selected from 3.82 ± 0.2, 7.57 ± 0.2, 8.12 ± 0.2, 10.53 ± 0.2, 11.39 ± 0.2, 12.00 ± 0.2, 13.54 ± 0.2, 15.15 ± 0.2, 16.35 ± 0.2, 16.88 ± 0.2, 17.37 ± 0.2, 18.51 ± 0.2, 18.98 ± 0.2, 19.77± 0.2, 21.06 ± 0.2, 22.70 ± 0.2, 23.47 ± 0.2, 24.66 ± 0.2 and 28.73 ± 0.2, when using Cu Kα radiation and a scan speed of 0.146°/s [Form D], more preferably having two or more diffraction peaks at 2[theta] values selected from 3.82 ± 0.2, 7.57 ± 0.2, 15.15 ± 0.2, 16.88 ± 0.2, 19.77± 0.2, 22.70 ± 0.2, 23.47 ± 0.2, 24.66 ± 0.2 and 28.73 ± 0.2 [Form D]; or (iv) a differential scanning calorimetry trace recorded at a heating rate of 10°C per minute which shows a maximum endothermic peak at a temperature between 145°C and 154°C. (i) an x-ray powder diffraction pattern having two or more diffraction peaks at 2[theta] values selected from 6.67 ± 0.2, 8.237± 0.2, 9.777 ± 0.2, 11.96 ± 0.2, 12.38 ± 0.2, 13.06 ± 0.2, 13.38 ± 0.2, 13.94 ± 0.2, 14.90 ± 0.2, 15.40 ± 0.2, 15.95 ± 0.2, 16.27 ± 0.2, 16.54 ± 0.2, 17.36 ± 0.2, 17.57 ± 0.2, 17.86 ± 0.2, 19.64 ± 0.2, 19.86 ± 0.2, 20.12 ± 0.2, 20.73 ± 0.2, 21.14 ± 0.2, 21.58 ± 0.2, 22.57 ± 0.2, 22.95 ± 0.2, 23.29 ± 0.2, 23.57 ± 0.2, 24.07 ± 0.2, 24.63 ± 0.2, 25.30 ± 0.2, 26.38 ± 0.2, 27.09 ± 0.2, 27.67 ± 0.2, 27.97 ± 0.2, 28.91 ± 0.2, 29.28 ± 0.2, 30.08 ± 0.2, 30.41 ± 0.2, 31.90 ± 0.2 and 34.49 ± 0.2, when using Cu Kα radiation and a scan speed of 0.146°/s (Form E), more preferably having two or more diffraction peaks at 2[theta] values selected from 6.67 ± 0.2, 13.06 ± 0.2, 13.38 ± 0.2, 14.90 ± 0.2, 17.36 ± 0.2, 17.57 ± 0.2, 19.64 ± 0.2, 20.73 ± 0.2, 23.57 ± 0.2 and 25.30 ± 0.2 (Form E); or (ii) a differential scanning calorimetry trace recorded at a heating rate of 20°C per minute which shows a maximum endothermic peak at a temperature between 176°C and 185°C; or (iii) an x-ray powder diffraction pattern having two or more diffraction peaks at 2[theta] values selected from 3.82 ± 0.2, 7.57 ± 0.2, 8.12 ± 0.2, 10.53 ± 0.2, 11.39 ± 0.2, 12.00 ± 0.2, 13.54 ± 0.2, 15.15 ± 0.2, 16.35 ± 0.2, 16.88 ± 0.2, 17.37 ± 0.2, 18.51 ± 0.2, 18.98 ± 0.2, 19.77± 0.2, 21.06 ± 0.2, 22.70 ± 0.2, 23.47 ± 0.2, 24.66 ± 0.2 and 28.73 ± 0.2, when using Cu Kα radiation and a scan speed of 0.146°/s [Form D], more preferably having two or more diffraction peaks at 2[theta] values selected from 3.82 ± 0.2, 7.57 ± 0.2, 15.15 ± 0.2, 16.88 ± 0.2, 19.77± 0.2, 22.70 ± 0.2, 23.47 ± 0.2, 24.66 ± 0.2 and 28.73 ± 0.2 [Form D]; or (iv) a differential scanning calorimetry trace recorded at a heating rate of 10°C per minute which shows a maximum endothermic peak at a temperature between 145°C and 154°C.