Crystalline forms of dihydropyrazolopyrimidinone

1. Crystalline Form G (monohydrate) of Compound A:

or a salt thereof,

having an X-ray powder diffraction pattern, obtained using Cu K alpha radiation, containing the following angle 2 theta values: 5.4°, 5.9° and 11.5°, and at least one angle 2 theta value selected from the group consisting of: 9.7°, 12.8°, 17.8°, 20.5°, 22.0°, 23.8°, 24.5° and 25.0°.

2. The crystalline form of claim 1 , Form G (monohydrate), having a differential scanning calorimetry (DSC) peak melting temperature of 124° C.

3. A compound which is 2-allyl-1-[6-(1-hydroxy-1-methylethyl)pyridin-2-yl]-6-{[4-(4-methylpiperazin-1-yl)phenyl]amino}-1,2-dihydro-3H-pyrazolo[3,4-d]pyrimidin-3-one monohydrate.

4. A pharmaceutical composition comprising a therapeutically-effective amount of the crystalline form of Compound A or a salt thereof as claimed in claim 1 , and pharmaceutically acceptable carrier or diluent.

5. A process for preparing crystalline Form G (monohydrate) of Compound A as defined in claim 1 , which is characterized by using an alcohol solvate or anhydrous of 2-allyl-1-[6-(1-hydroxy-1-methylethyl)pyridin-2-yl]-6-{[4-(4-methylpiperazin-1-yl)phenyl]amino}-1,2-dihydro-3H-pyrazolo[3,4-d]pyrimidin-3-one as a raw material, dissolving the said alcohol solvate or anhydrous in an aqueous-organic mixed solvent, and crystallizing the intended crystalline Form G (monohydrate).

6. The process of claim 5 , which comprises the steps of:

(a) dissolving the isopropanol solvate of Compound A in a mixture of ethanol and water at 25-65° C. to form a solution;

(b) adding water to the solution of step (a) while keeping the temperature over 40° C.;

(c) seeding the solution of step (b) with one or more crystals of the intended crystalline Form G (monohydrate) over 40° C.;

(d) aging the solution of step (c) over 40° C. for over 1 hour;

(e) adding water to the solution of step (d) for over 1 hour at about 50° C. to form slurry;

(f) cooling the slurry of step (e) to ambient temperature;

(g) aging the slurry of step (f) for over 0.5 hour at the same temperature as step (f);

(h) optionally further aging the slurry of step (g) below 5° C. for over 0.5 hour; and

(i) collecting the crystals from the slurry of step (h).

7. A crystalline form of 2-allyl-1-[6-(1-hydroxy-1-methylethyl)pyridin-2-yl]-6-{[4-(4-methylpiperazin-1-yl)phenyl]amino}-1,2-dihydro-3H-pyrazolo[3,4-d]pyrimidin-3-one, which is prepared by the process of claim 6 .

8. A compound which is 2-allyl-1-[6-(1-hydroxy-1-methylethyl)pyridin-2-yl]-6-{[4-(4-methylpiperazin-1-yl)phenyl]amino}-1,2-dihydro-3H-pyrazolo[3,4-d]pyrimidin-3-one isopropanol solvate.