Claiming the Amorphous Form, Not the Crystal A Divisional on a BTK Inhibitor Whose Title Says Crystalline

This application is about a cancer drug candidate that the specification calls Compound 1, a covalent inhibitor of Bruton’s tyrosine kinase. The title still says “Crystalline form”, but claim 1 is not about a crystal at all. It claims the amorphous (non-crystalline) form of Compound 1, provided its enantiomeric excess is at least 90 per cent, and the remaining claims cover a lyophilised version, tablets and capsules, a chiral acid salt used to make the pure mirror-image form, and treatment of B-cell cancers. BeOne Medicines I GmbH filed it as a divisional of Australian application 2024200030, and it names Zhiwei Wang, Yunhang Guo and Gongyin Shi as inventors.

The Problem

Compound 1 is (S)-7-(1-acryloylpiperidin-4-yl)-2-(4-phenoxyphenyl)-4,5,6,7-tetrahydropyrazolo[1,5-a]pyrimidine-3-carboxamide. The specification never gives it a drug name, but the structure and the Btk target match zanubrutinib, the BeiGene (now BeOne) drug sold as Brukinsa. That match comes from public records, not from the specification.

The background explains why the physical form of the drug matters. Compound 1 was first made in an earlier international application, WO2014173289, and it came out as an amorphous solid. The specification confirms this with an X-ray powder diffraction trace and then points out that the amorphous material has a low glass transition temperature, which it says brings “low stability and hard to purify” and makes drug formulation difficult. It reports the mid-point glass transition at 79.7 degrees C.

There is also a second problem hiding under the first. The molecule has one chiral centre, and only the S form is wanted. The specification shows that how pure that S form is controls everything downstream, including whether you can crystallise the material at all. A batch that is only 90 per cent enantiomeric excess behaves very differently from one at 97 per cent or better.

What This Invention Does

The original filing was about Crystalline Form A, a stable crystal of Compound 1 with a sharp melting point. This divisional goes after the other end of the same story. Claim 1 is “an amorphous form of Compound 1” with an enantiomeric excess of at least 90 per cent. Claim 2 narrows this with a glass transition mid-point of about 79.7 degrees C, an enantiomeric excess of at least 97 per cent, and a purity of at least 99.3 or 99.5 per cent. Claim 3 puts that amorphous form into a pharmaceutical composition with an excipient. Claim 7 claims a lyophilised amorphous form, which is the freeze-dried material the examples use as the starting point.

Claims 9 to 15 reach back into manufacture. They cover chiral acid salts of an intermediate (Formula Id) made with acids such as malic, mandelic, camphorsulfonic, tartaric, DBTA or DTTA, with L-DBTA named in claim 10, and a method of making those salts. This is a classic chiral resolution: mix the racemic or mixed intermediate with a single-handed acid, let the salt of one handed form precipitate, filter it, then carry on to the final drug by removing the protecting group and adding acryloyl chloride. Claim 17 then claims “a solid of Compound 1” with an enantiomeric excess of at least about 97 per cent, claim 18 adds that it can be an anhydrate, and claims 19 and 20 cover treating B-cell proliferative diseases at 160 mg twice a day or 320 mg once a day.

The numbers in the examples are what tie these claims together. Resolving the intermediate with L-DBTA took a salt at 85.6 per cent enantiomeric excess up to above 98.5 per cent in 72 per cent yield after recrystallisation from THF and water. A free base at 90.5 per cent was taken above 98 per cent in 80 per cent yield with 0.55 equivalents of L-DBTA in acetonitrile and water. At plant scale, 8.5 kg of the intermediate gave 9.08 kg of salt, a 74.8 per cent yield, above 98 per cent enantiomeric excess. Crystallisation then acts as a purification step: silica gel chromatography left Compound 1 at 98.5 per cent area purity, a first recrystallisation took it to 99.3 per cent and a second to 99.5 per cent.

Key Features

• Amorphous Compound 1 with a floor on chirality. Claim 1 requires an enantiomeric excess of at least 90 per cent, and dependent claims lift that to 97 per cent and a purity of 99.5 per cent.
• A stated glass transition. The mid-point glass transition temperature is given as about 79.7 degrees C, which the specification itself regards as low.
• Lyophilised amorphous form. Claim 7 covers the freeze-dried amorphous solid, and the examples show it is the form used as the starting material for the crystallisation work.
• Chiral acid salt of the intermediate. Claim 9 covers the salt of the Formula Id intermediate with a named list of chiral acids, and claim 10 narrows it to L-DBTA.
• Dose forms and doses. Claim 4 gives single units of about 40 mg or 80 mg, and a composition of about 160 mg. The treatment claims cover 40 to 320 mg a day, 160 mg twice daily or 320 mg once daily, taken orally.
• A defined list of diseases. The treated conditions are chronic lymphocytic leukemia, small lymphocytic lymphoma, mantle cell lymphoma, Waldenstrom’s macroglobulinemia, marginal zone lymphoma and follicular lymphoma.
• Crystallisation depends on purity. Starting from amorphous material at 90 per cent enantiomeric excess gave very little solid, and one sample showed only 45 per cent enantiomeric excess. Starting from 97 per cent gave a noticeable amount of solid.

Who Is Behind It

The applicant is BeOne Medicines I GmbH, the Swiss-registered entity of the oncology company formerly called BeiGene. The company’s own site at beonemedicines.com describes it as building an oncology company and its news items mention the drug Brukinsa. The specification’s own tables contain the older company name (a TR-FRET assay is described as run at BeiGene), which fits a family filed under the old name and carried forward under the new one.

On the family position, the specification is explicit. It says this is a divisional under section 79B of the Patents Act of Australian application 2024200030, filed 3 January 2024, itself a divisional of Australian application 2022200278, filed 17 January 2022, which is a divisional of Australian application 2017314178. That last application corresponds to PCT/IB2017/054955, filed 15 August 2017, which claims priority from PCT/CN2016/095510, filed 16 August 2016. A Chinese-origin first filing is therefore the priority country, and the document says so itself rather than leaving it to be inferred.

Three divisional generations deep, with a title that describes the crystal and claims that describe the amorphous form, is typical of a family where the applicant keeps carving out distinct pieces of the same disclosure.

Why It Matters

For a drug taken daily in doses of 160 to 320 mg, the physical form of the active ingredient has regulatory and commercial weight. The specification itself says the amorphous material was hard to purify and low in stability, which is why it went looking for a crystal. Yet the drug has to be made and the material that comes off a process line, or out of a freeze dryer, is often amorphous. Claiming the amorphous form with defined chirality and purity protects that version as well, not just the crystalline one.

The chirality claims are the other half of the story. A covalent inhibitor made from the wrong mirror image is a different substance, and the specification shows that the cheapest way to control it is a salt resolution early in the route. Claims on that salt cover a step that any competing manufacturer using the same route would have to pass through. The specification is silent on commercial strategy, and the clinical dosing claims reproduce the dosing schedules without giving clinical outcome data.

Related Concepts

• Bruton’s tyrosine kinase – the enzyme in B-cell signalling that Compound 1 irreversibly inhibits.
• Ibrutinib – the first-generation Btk inhibitor the specification compares Compound 1 against for selectivity.
• Amorphous solid – the non-crystalline state of matter that claim 1 is directed to.
• Glass transition – the temperature property, 79.7 degrees C here, that marks where the amorphous solid softens.
• Freeze drying – the lyophilisation step that produces the lyophilised amorphous form in claim 7.

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AU 2026202253 was published in the Australian Official Journal of Patents on 9 April 2026 and is open for public inspection. Patent applications represent inventions that are sought to be protected and do not necessarily reflect commercially available products.