Revocation of Valganciclovir patent by Controller of Patents, Chennai

Recently in a matter remanded from IPAB to Controller of Patents, Chennai, a decision of revoking Roche’s patent IN207232 for Valganciclovir was delivered after hearing both the parties. The subject patent was granted on January, 2009 followed which post grant oppositions were separately filed by CIPLA, Matrix, Ranbaxy and Bakul Pharma along with two NGOs Delhi Network of Positive People and lndian Network for People living with HIV/AIDS & The Tamil Nadu Networking People with HIV/AIDS (hereinafter INP+ and TNNP+), wherein INP+ and TNNP+ were allowed by the Apex court to raise all contentions in the form of an intervention cum affidavit before the Assistant Controller and the parties agreed to be heard along with CIPLA, Matrix, Ranbaxy and Bakul Pharma. In the opposition proceedings, the patent was revoked limiting it to single process claim by the Controller of Patents on 30.04.2010 and being aggrieved by this decision, Roche filed an appeal at IPAB challenging the decision. IPAB on 30.01.2014 set aside the Patent Controller’s decision to revoke the patent on technical grounds and remanded it to the Controller for re-consideration.

Issues before the controller:

• Determining whether the expert evidence was prior art publication or disclosure

Answering the issue, controller observes that the expert evidence is not a prior art document to be relied upon for deciding a case, but it may be considered for understanding the prior art documents, if the evidence covers such prior art documents. The opinion of the expert evidence, if it is based on further laboratory or animal study of a given subject matter, it cannot be considered for concluding such invention because it is later acquired knowledge, but it can be used for understanding the present invention. Therefore, expert evidences cannot be considered as prior publications/disclosures, but it can be taken as opinion on the prior arts.

• Deciding upon the obviousness of the present invention

The next issue which the controller addressed was whether the present invention was obvious with respect to prior art references. The controller observes that the present invention is obvious against two prior arts US 4957924 and EP 0375329A2.

Claim 1 of the present invention recites,

1. The compound 2-{2-amino-1, 6-dihydro-6-oxo-purin-9-yl} methoxy-3-hydroxy-1-propanyl-L-valinate or a pharmaceutically acceptable salt thereof, in the form of its (R) or (S)- diastereomers, on in the form of mixtures of the two diastereomers.

Regarding this , the controller states that the monovaline ester of ganciclovir is disclosed in the form of Markush formula in EP ‘329, which covers both monovaline and di-valine ester of ganciclovir where support for the both mono and di-valine ester of gancicloviris is provided in the specification. Thus the disclosure of EP ‘329 is clear and unmistakable direction to the mono valine ester of ganciclovir. Hence, a skilled person working in the synthetic chemistry field can easily arrive at the present invention without further experimentation. Therefore mono valine ester of present invention is anticipated by EP’329. Controller further emphasizes that claim 1 of EP ‘329 clearly and unambiguously discloses as at least one of the substituents is valine residue which indicate the presence of mono valine ester. Therefore, EP’329 undoubtedly disclosed mono valine ester of ganciclovir.

With respect to process claim, controller observes that the synthetic method for preparing mono valine ester of ganciclovir as claimed in independent claim 12 of present invention may not be explicitly disclosed in EP ‘329, but said method is just a general method for coupling acid group in the amino acid with hydroxyl group, which can be adopted for any type of alcohols. Therefore, using EP’329, a person working in the synthetic chemistry can easily prepare ester of ganciclovir with lysine without undue burden.

Further the controller observes that the object of the present invention is to provide a prodrug of ganciclovir with improved oral bioavailability. Controller notes that the solution for poor absorption in the gastrointestinal tract for acyclovir is disclosed in US ‘924 patent. Therefore a person skilled in the art can perceive to prepare mono valine ester of ganciclovir from the teachings of both EP’329 and US’924 references. Thus all the claims including process claim are obvious to a skilled person in the art.

• Deciding upon the efficacy of substance under the subject patent under section 3 (d)

Deciding upon the efficacy of substance under the subject patent, the Controller observes that the new form L-monovaline ester of ganciclovir molecule has shown improvement in oral bioavailability than bis-valine ester of ganciclovir and ganciclovir, whereas there is no support in the specification pertaining to efficacy. Controller observes that the ester modification of the present invention was made to protect the substance from destruction in the gastrointestinal tract and make the molecule more bioavailable. Thus the controller has ruled that while bioavailability is one of the factors affecting efficacy, it cannot be directly equated to efficacy. Citing Hon’ble Supreme Court of India’s decision on Novartis case, the Controller rules that: “lmprovement in bioavailability of the new form cannot be considered directly related to efficacy. Even any unforeseen property observed in new form, unless such property directly relate to efficacy, it will be considered as inherent property of such substance. Since there is no direct relation shown for the improved bioavailability of new form of ganciclovir in the description with regard to significant difference in the efficacy, and therefore such a new form shall be considered as a same substance. Thus new form of the present case Monovaline ester of ganciclovir is considered as a same substance i.e. ganciclovir because,the difference in enhanced efficacy is not shown in the complete specification.” According to the controller, since there is no direct relation shown for the improved bioavailability of new form of ganciclovir in the description with regard to significant difference in the efficacy, therefore such a new form shall be considered as a same substance. Further regarding process used for preparing present invention, the controller held that the process used to prepare new form is a conventional process as it is already known process as disclosed in EP ‘329. Thus, the Controller rules that the present patent was a ‘mere use of a known process’ which was not patentable under S. 3(d), Patents Act.

• Locus standi of the two NGOs as “person interested” under section 2(1)(t)

Deciding the locus standi of the two NGOs, as person interested under section 2 (1)(t) of patent act, Controller notes that NGOs would fall under the ambit of persons interested as the criteria of locus standi in post grant opposition is to be viewed in broader perspective to grant quality patent. According to the Controller, the two NGOs are the end users or directly affecting parties, if the patent is granted. Thus it is held by the controller that viewing in to the broader prospective, the two NGOs falls under the purview of under section 2 (1)(t) of the patent act and hence the parties have locus standi to oppose the patent.

Thus hearing all the parties and considering all facts and relevant arguments, the Controller revoked the patent granted for the drug Valganciclovir under section 25(4) of Indian Patent act.

About the Author: Mr. Sitanshu Singh, Patent Associate at Khurana & Khurana, Advocates and IP Attorneys and can be reached at: [email protected].