In its recent decision, in Srinivas Jegannathan vs Controller of Patents and Designs [(T)CMA(PT)/38/2023], the Madras High Court set aside the order passed by the Controller in patent application number 122/CHE/2006, entitled “Formulation of Ceftazidime, Tazobactum and Linezolid for Enhancement of Antibacterial Activity“, and remanded the application to the Patent Office for re-consideration.

The Application was refused by the Controller on the grounds that the claim amendments introduced by the Appellant were impermissible under Section 59 of the Patents Act and the claimed invention lacked inventive step in view of cited prior art references D1 to D6.

The as-filed application claimed a pharmaceutical composition of ceftazidime (a cephalosporin antibiotic) in a fixed dose combination with linezolid (an oxazolidinone antibiotic), along with a beta-lactamase inhibitor, tazobactum. Based on the interaction with the Controller during the hearing, the Appellant amended the claims to recite in claim 1, a drug delivery system consisting of ceftazidime, beta-lactamase inhibitor such as tazobactum, and oxazolidinone such as linezolid. Claim 4 of the amended claim set was broadly in line with the as-filed claim 1 and the dependent claim 2.

During the appeal proceedings, the Appellant submitted that they were willing to proceed with the original claims if the matter was to be remanded. Notably, if the original claims were to be considered, the objection pertaining to Section 59 as well as lack of inventive step in view of D4 to D6 would lose relevance, since documents D4-D6 pertained primarily to drug delivery systems and not to the pharmaceutical composition originally claimed. The Appellant also asserted that there was no teaching in documents D1-D3 that would make the claimed combination of ceftazidime, linezolid, and tazobactum obvious to a person skilled in the art (PSITA). It was pointed out that:

• D1 disclosed compositions of linezolid with other antibacterial agents including cephalosporins, but did not mention a beta-lactamase inhibitor.
• D2 disclosed oxazolidinones combined with ampicillin and sulbactum, but not cephalosporins.
• D3 disclosed clavulanate as a beta-lactamase inhibitor but not the active ingredients of the claimed invention.

In response, the Controller argued that since the Appellant voluntarily amended the claims multiple times, the last set of amended claims had to be examined. Reliance was placed on the Madras High Court’s earlier decision in Genomatica Inc. vs Controller of Patents [CMA(PT)/4/2023], where the Court had emphasized that examination must be based on the last amended claims. It was also contended that a combined reading of the cited prior art documents rendered the claimed invention obvious, and, therefore the refusal was justified.

The Court carefully considered the amended claims and the as-filed claims and found that independent claim 1 of the original claim was broadly in line with independent claim 4 of the rejected claims. The difference is that, in independent claim 4 of the rejected claims, the concentration of each ingredient is specified, whereas it is absent in independent claim 1 of the original claims. The ratios, however, are indicated in dependent claim 2 of the original claims.

In examining the objection of lack of inventive step, the Court noted that while documents D1-D3 disclosed parts of the claimed invention, none disclosed the three-way cephalosporin combination of cephalosporin + linezolid + tazobactum. The Controller’s conclusion that the claimed invention was already known was held to be unsupported by proper reasoning. The impugned order simply asserted that the ingredients and ratios were “well known” in prior art, without explaining why it would be obvious to a PSITA to combine them. This lack of reasoning rendered the order unsustainable.

Further, the Court accepted the Appellant’s submission to revert to the original claims. As a result, the reliance placed by the Controller on documents D4-D6, which were relevant only to the amended drug delivery system claims, no longer survived for consideration. For the same reason, the objection under Section 59 of the Patents Act, which had been triggered by the amendments, also ceased to have any bearing.

In view of the foregoing, the Court set aside the impugned order and remanded the matter to the Patent Office for fresh consideration.