02 March 2020

Patents – Cobicistat is not derivative of Ritonavir – Differences in structure when not mere structural modification

Rejecting the pre-grant opposition filed by a patient group, a community-based non-profit organisation, the Assistant Controller of Patents at New Delhi has granted an Indian patent to Cobicistat, marketed under trade name Tybost, a licensed drug for use in the treatment of HIV and AIDS. The opponents had pleaded lack of inventive step, no enhanced therapeutic efficacy, and being a mere admixture resulting only in the aggregation of the properties of the components.

The Patent office was of the view that claimed invention was not obvious for a person skilled in the art with respect to the cited prior documents and that the applicant had also shown that claimed compound had no appreciable protease inhibition activity but acts as an excellent pharmacokinetic enhancer. The claims were considered to involve an inventive step as required under Section 2(1)(ja) of the Patents Act.

The Assistant Controller in its decision dated 24th of February, 2020 also held that that Cobicistat is not a derivative of Ritonavir in view of structural differences between cobicistat and ritonavir, i.e. presence of morpholine group in place of isopropyl and absence of hydroxyl group at a position. Observing that such differences in structure cannot be considered as mere structural modification carried out as part of development of derivatives of ritonavir, it was held that the claimed compounds are not to be considered as mere discovery of new forms, i.e. derivative of the known compound ritonavir, and hence does not fall within the scope of Section 3(d) of the Patents Act.

Similarly, pleas of lack of clarity and insufficient disclosure by the applicant were also rejected in the pre-grant opposition filed by Uttar Pradesh Welfare for People Living with HIV/AIDS Society in Patent Application Number 10487/DELNP/2008 filed by Gilead Sciences, Inc. The Office of Controller observed that various schemes of preparation of cobicistat were described in the specification.

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