DESC:FIELD OF THE INVENTION
The present application relates to process for preparation of amorphous form of Trilaciclib dihydrochloride, and pharmaceutical compositions comprising amorphous form of Trilaciclib dihydrochloride.

BACKGROUND OF THE INVENTION
The drug compound having the adopted name Trilaciclib, has a chemical name 2'-((5-(4-methylpiperazin-1-yl)pyridin-2-yl)amino)-7',8'- dihydro-6'H-spiro[cyclohexane-1,9'- pyrazino[1',2':1,5]- pyrrolo[2,3-d]pyrimidin]-6'-one, and is represented by the structure of formula I.

Trilaciclib dihydrochloride is approved as CDK4 Kinase Inhibitor to decrease the incidence of chemotherapy-induced myelosuppression in adult patients when administered prior to a platinium/etoposide-containing regimen or topotecan-containing regimen for extensive-stage small cell lung cancer. Trilaciclib dihydrochloride is represented by the structure of formula IA.

Trilaciclib, its synthetic process and its pharmaceutical compositions are described in US patent No. 8,598,186 and US patent No. 10,189,849.
US patent No. 10,988,479 describes polymorphic forms of Trilaciclib base and Trilaciclib dihydrochloride salt.
PCT application WO 2022/076779 A1 also describes polymorphic forms of Trilaciclib base and various salts of Trilaciclib like hydrochloric acid, hydrobromic acid, citric acid, acetic acid, formic acid, propionic acid, trifluoroacetic acid, sulfuric acid, methane sulfonic acid and benzene sulfonic acid.
Polymorphism, the occurrence of different crystal forms, is a phenomenon of some molecules and molecular complexes. A single molecule may give rise to a variety of polymorphs having distinct crystal structures and physical properties. Polymorphs in general will have different melting points, thermal behaviors (e.g. measured by thermogravimetric analysis - "TGA", or differential scanning calorimetry - "DSC"), X-ray powder diffraction (XRPD or powder XRD) pattern, infrared absorption fingerprint, and solid state nuclear magnetic resonance (NMR) spectrum. One or more of these techniques may be used to distinguish different polymorphic forms of a compound.
Discovering new polymorphic forms, hydrates and solvates of a pharmaceutical product can provide materials having desirable processing properties, such as ease of handling, ease of processing, storage stability, and ease of purification or as desirable intermediate crystal forms that facilitate conversion to other polymorphic forms. New polymorphic forms and solvates of a pharmaceutically useful compound or salts thereof can also provide an opportunity to improve the performance characteristics of a pharmaceutical product. It enlarges the repertoire of materials that a formulation scientist has available for formulation optimization, for example by providing a product with different properties, e.g., better processing or handling characteristics, improved dissolution profile, or improved shelf-life. For at least these reasons, there is a need for additional solid forms of Trilaciclib dihydrochloride.

SUMMARY OF THE INVENTION
The present application provides process for preparation of amorphous forms of trilaciclib dihydrochloride.
In one aspect the present application provides a process for preparation of
amorphous form of trilaciclib dihydrochloride, comprising:
a) providing a solution of trilaciclib dihydrochloride in a suitable solvent or a mixture of solvents,
b) evaporating the solvent, and
c) isolating amorphous form of trilaciclib dihydrochloride.
In another aspect the present application provides pharmaceutical compositions comprising amorphous form of Trilaciclib dihydrochloride described in this application and one or more pharmaceutically acceptable excipient.

BRIEF DESCRIPTION OF DRAWINGS

Figure-1 is powder X-ray diffraction (PXRD) pattern of amorphous form of Trilaciclib dihydrochloride prepared according to example 1.
Figure-2 is powder X-ray diffraction (PXRD) pattern of amorphous form of Trilaciclib dihydrochloride prepared according to example 2.
Figure-3 is powder X-ray diffraction (PXRD) pattern of amorphous form of Trilaciclib dihydrochloride prepared according to example 3.

DETAILED DESCRITPION OF THE INVENTION
In one aspect the present application provides a process for preparation of
amorphous form of trilaciclib dihydrochloride, comprising:
a) providing a solution of trilaciclib dihydrochloride in a suitable solvent or a mixture of solvents,
b) evaporating the solvent, and
c) isolating amorphous form of trilaciclib dihydrochloride.

Providing a solution in step (a) includes direct use of a reaction mixture containing Trilaciclib dihydrochloride that is obtained in the course of its synthesis or dissolving Trilaciclib or its dihydrochloride salt in a solvent or a mixture of solvents or dissolving Trilaciclib base along with hydrochloric acid solution in a solvent or a mixture of solvents.
The suitable solvent of the process of the present invention may be selected from the group consisting of alcohols, such as methanol, ethanol, 2-propanol, n- propanol, n-butanol, isoamyl alcohol, octanol, 1,2-propanediol, S-(+)-1,2-propanediol and ethylene glycol; ethers, such as diisopropyl ether, dibutyl ether, cyclopentyl methyl ether, methyl tert-butyl ether, diethyl ether, 1,4-dioxane, tetrahydrofuran (THF), methyl THF, and diglyme; esters, such as methyl acetate, ethyl acetate, isopropyl acetate, n-propyl acetate and t-butyl acetate; ketones, such as acetone, methyl ethyl ketone, cyclohexanone and methyl isobutyl ketone; halogenated hydrocarbons, such as dichloromethane, dichloroethane, chloroform, carbon tetrachloride and the like; nitriles, such as acetonitrile; hydrocarbons include but not limited to such as benzene, toluene, xylene, pentane, hexane, heptane, cyclohexane and tetraline; polar aprotic solvents, such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl 2-pyrrolidone, dimethylsulfoxide, pyridine, phenol, DMA, carbon disulphide, acetic acid and the like; water; or mixtures thereof.
In another aspect, the suitable solvent of the process of the present invention is preferably selected from methanol, dichloromethane and water or a mixture thereof.
The mixture may be heated to suitable temperatures to dissolve the solid. After dissolution the solution may be filtered to remove any undissolved solid particles.
The solution may be stirred for about 10 minutes to about 2 hours, or longer.
The step (b) involves removal of solvent by methods known in the art or any procedure disclosed in the present application. In a preferred aspect, removal of solvent may include, but not limited to: solvent evaporation or sublimation under atmospheric pressure or reduced pressure / vacuum such as a rotational distillation using Büchi® Rotavapor®, spray drying, freeze drying (Lyophilization), agitated thin film drying and the like.
The step (c) involves isolation of amorphous Trilaciclib dihydrochloride from the vessel. The resulting solid may be optionally further dried. Drying may be suitably carried out using equipment such as a tray dryer, vacuum oven, air oven, fluidized bed dryer, spin flash dryer, flash dryer, or the like, at atmospheric pressure or under reduced pressure. Drying may be carried out at temperatures less than about 100°C, less than about 60°C, less than about 40°C, or any other suitable temperatures, at atmospheric pressure or under reduced pressure, and in the presence or absence of an inert atmosphere such as nitrogen, argon, neon, or helium. The drying may be carried out for any desired time periods to achieve a desired purity of the product, such as, for example, about 1 to about 15 hours, or longer.
In another aspect, the present application provides pharmaceutical composition comprising amorphous form of Trilaciclib dihydrochloride of the present invention and one or more pharmaceutically acceptable carriers.
The compound of this application can be characterized by X-ray powder diffraction pattern determined in accordance with procedures that are known in the art. X-ray diffraction was measured using PANalytical X-ray diffractometer, Model: Empyrean. System description: CuK-Alpha 1 wavelength= 1.54060, voltage 45 kV, current 40 mA, divergence slit = 1/4°; Sample stage=Reflection-spinner. Revolution time [s]: 1.000; Scan type: Pre-set time; Detector – Pixcel; Measurement parameters: Start Position [°2Th.]: 3.0066; End Position [°2Th.]: 39.9916; Step Size [°2Th.]: 0.0130; Scan Step time [s]: 1.000.

DEFINITIONS
The following definitions are used in connection with the present application unless the context indicates otherwise.
The term "about" when used in the present application preceding a number and referring to it, is meant to designate any value which lies within the range of ±10%, preferably within a range of ±5%, more preferably within a range of ±2%, still more preferably within a range of ±1 % of its value. For example, "about 10" should be construed as meaning within the range of 9 to 11, preferably within the range of 9.5 to 10.5, more preferably within the range of 9.8 to 10.2, and still more preferably within the range of 9.9 to 10.1.
All percentages and ratios used herein are by weight of the total composition and all measurements made are at about 25°C and about atmospheric pressure, unless otherwise designated. All temperatures are in degrees Celsius unless specified otherwise. As used herein, “comprising” means the elements recited, or their equivalents in structure or function, plus any other element or elements which are not recited. The terms “having” and “including” are also to be construed as open ended. All ranges recited herein include the endpoints, including those that recite a range “between” two values. Whether so indicated or not, all values recited herein are approximate as defined by the circumstances, including the degree of expected experimental error, technique error, and instrument error for a given technique used to measure a value.
Certain specific aspects and embodiments of the present application will be explained in greater detail with reference to the following examples, which are provided only for purposes of illustration and should not be construed as limiting the scope of the application in any manner. Reasonable variations of the described procedures are intended to be within the scope of the present invention. While particular aspects of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.
EXAMPLES
Example-1: Preparation of amorphous form of Trilaciclib dihydrochloride
Trilaciclib dihydrochloride (5 g), methanol (170 mL) and dichloromethane (170 mL) were charged into a 500 mL Buchi flask. The mixture was stirred for 10 minutes at 40 °C. Filtered the solution to get particle free solution and the clear solution was evaporated using a spray drier at 65 °C. The solid obtained dried at 30 °C for 20 hours and dried at 50 °C for 20 hours using a VTD to obtain 3.2 g of yellow colored solid. PXRD pattern is shown in Figure 1.

Example-2: Preparation amorphous form of Trilaciclib dihydrochloride
Trilaciclib free base (3 g), methanol (90 mL) and dichloromethane (90 mL) were charged into a 500 mL Buchi flask. 5% aqueous hydrochloric acid (15.6 mL) was added slowly at 25 °C. The mixture was stirred for 10 minutes at 45 °C. Filtered the solution to get particle free solution and the clear solution was evaporated using a spray drier at 65 °C. The solid obtained dried at 30 °C for 20 hours and dried at 50 °C for 6 hours using a VTD to obtain 2.8 g of yellow colored solid. PXRD pattern is shown in Figure 2.

Example-3: Preparation of amorphous form of Trilaciclib dihydrochloride
Trilaciclib dihydrochloride Pattern 2 (3 g), methanol (90 mL) and dichloromethane (90 mL) were charged into a 500 mL Buchi flask. The mixture was stirred for 10 minutes at 45 °C. Filtered the solution to get particle free solution and the clear solution was evaporated using a spray drier at 65 °C. The solid obtained dried at 30 °C for 20 hours and dried at 50 °C for 20 hours using a VTD to obtain 3.2 g of yellow colored solid. PXRD pattern is shown in Figure 3. ,CLAIMS:1. A process for preparation of amorphous form of trilaciclib dihydrochloride, comprising:
a) providing a solution of trilaciclib dihydrochloride in a suitable solvent or a mixture of solvents,
b) evaporating the solvent, and
c) isolating amorphous form of trilaciclib dihydrochloride.
2. The process according to claim 1, wherein the solvent is methanol or dichloromethane.
3. The process according to claim 1, wherein the solvent is a mixture of methanol and dichloromethane.
4. The process according to claim 1, wherein the trilaciclib dihydrochloride is formed by reacting trilaciclib base with hydrochloric acid.
5. The process according to claim 1, wherein the trilaciclib dihydrochloride used is crystalline trilaciclib dihydrochloride.
6. The process according to claim 5, wherein the crystalline trilaciclib dihydrochloride is crystalline trilaciclib dihydrochloride pattern 2.
7. A pharmaceutical composition comprising amorphous form of trilaciclib dihydrochloride prepared by the process described in this application, and a pharmaceutically acceptable carrier.