Gilead’s 712/del/2002 application relates to a crystalline adefovir dipivoxil. AD is the bis pivaloyloxmethyl ester of the parent compound 9-[2-[[bis[(pivaloyloxy)-methoxy]phosphinyl]methoxy]ethyl]adenine,(PMEA) and the method of preparation thereof. The compound is active against Hepatitis B virus. Both the parent compound and the ester are well known in art.
The claim 1 at issue was directed to crystalline AD which may be selected from anhydrous with specific monoclinic cell parameters and XRD, hydrate with specific XRD and DSC, methanol solvate with specific XRD and DSC, fumaric acid salt with specific XRD and DSC.
Opponent Ranbaxy ‘s basis for opposition was majorly based on section 3(d) - polymorph of AD, it will be regarded as the same substance unless it shows enhanced efficacy over the known substance i.e. amorphous AD. Ranbaxy put forth that the applicant had submitted that the crystalline AD form has – good melting point and/or bulk density properties facilities manufacturing and formulation of compositions containing AD: at least 97%(w/w) purity and enhanced dissolution rate and submitted that since all these relate to physical properties of the compound, therapeutic efficacy is not established. Controller stated “I have analyzed the results as provided by the applicants regarding improved stability of the alleged compound. I have observed that the applicants have not provided a comparative data with respect to the amorphous/parent compound of the alleged invention. Also no improvement in the therapeutic efficacy of AD as compared to its parent compound (PMEA) has been provided. In fact both the compounds (AD) is used to treat viral infections which is also the activity shown by the parent compound (PMEA). In view of above I state that the subject matter for application no. 712/DEL/2002 is not patentable under section 3(d)”
With respect to Novelty all the prior arts relied upon were silent on crystalline AD. Hence the controller stated “Since, the Opponent failed to present or identify any document in this context, the ground of lack of novelty under Section 25(1)(b) taken by the Opponent is not maintainable and hence should be rejected. I would thus hold the compound to be novel”
With respect to the invention step controller stated “I find that various cited documents especially US4808716 and US5663159 synthesise the parent compound (PMEA) as a crystalline solid. Since the compound of the invention (AD) is an ester form of the parent compound (PMEA) no inventive technical advancement can be attributed to the alleged invention. I have analysed the results as provided by the applicants regarding improved stability of the alleged compound. I have observed that the applicants have not provided a comparative data with respect to the amorphous/parent compound of the alleged invention. In the absence of the same an inventive step cannot be established."
Subscribe to:
Post Comments (Atom)
No comments:
Post a Comment