There is a sentence patent agents dread in any Section 3(d) refusal: “the applicant has failed to establish enhancement of therapeutic efficacy.” But there is a world of difference between an invention that cannot show enhanced efficacy and an applicant who simply has not yet put the proof on the table. In Daewoong Pharmaceutical Co. Ltd. v. Controller General of Patents [C.A.(COMM.IPD-PAT) 23/2022], the Delhi High Court drew exactly that line — and let the applicant cure the second problem on appeal.
A known compound, a new form, and a missing column of data
The application (no. 201817048074), titled “Method of Producing Diphenylmethane Derivative,” concerned an improved route to a diphenylmethane compound useful as an SGLT inhibitor. The compound itself (Formula C28) was already known from the prior art (D1) cited in the First Examination Report; what Daewoong put forward was a crystalline Form-A, characterised by XRD, said to deliver improved therapeutic efficacy.
The Controller’s refusal had an unusually candid structure. The comparative data on stability, non-hygroscopicity, solubility and dissolution rate was, the Controller accepted, enough to satisfy Section 2(1)(ja) — there was a technical advance. But those, the Controller held, are physico-chemical and pharmacokinetic properties; under Section 3(d), and under the strict Novartis therapeutic-efficacy yardstick, they did not establish enhanced ‘therapeutic efficacy.’ The application was refused.
Evidentiary gap, not intrinsic defect
On appeal, the central question was whether that gap could be filled late. The Court’s framing was the crux: the refusal “was not based on a substantive finding that enhanced efficacy was absent,” but on the applicant’s failure to meet the evidentiary threshold at the time of consideration. The deficiency was evidentiary, not intrinsic to the invention — and evidentiary deficiencies can be cured.
Procedurally, the Court leaned on its appellate powers under Order XLI Rules 27–29 of the CPC, which allow additional evidence to be admitted, and either evaluated by the appellate court (after a chance to rebut) or sent to the court/authority below to record and return. The Court allowed Daewoong to bring the further efficacy data on affidavit, and held it should, in the first instance, go back to the Controller. An equitable sweetener helped: the data could not be generated earlier because of COVID-19 disruption, which the Court accepted as reasonable.
On the law, the Court reinforced that nothing in the Patents Act bars an applicant from submitting additional data to overcome an objection, relying on the IPAB’s decision in University of Miami v. Controller of Patents. That, the Court noted, aligns Indian practice with international prosecution norms, where post-filing data routinely substantiates an asserted technical effect. The order was set aside and remanded de novo but only on the Section 3(d) objection; the favourable Section 2(1)(ja) finding was preserved, narrowing the second round.
Why it matters — and the line to watch
Daewoong is the patentee-friendly counterpoint to the orthodoxy that efficacy and synergy must be demonstrated in the specification as filed. Read alongside this blog’s coverage of Crystal Crop — where the Court insisted that synergy be “clearly brought out in the description … at the time of filing” — the two decisions are not in conflict so much as in tension about which kind of gap is fatal. Crystal Crop never demonstrated an interaction at all; Daewoong asserted enhanced efficacy in the specification but under-evidenced it. The first is a substantive hole; the second, the Court says, is a procedural one that Order XLI Rule 27 can fill.
That is a principled distinction, but a slippery one, and it is the line every examiner and applicant will now fight over. The comparison is irresistible with the EPO’s Enlarged Board decision in G 2/21, which permits reliance on post-published evidence only where the effect is one the skilled person would derive as “encompassed by the technical teaching and embodied by the same originally disclosed invention.” Indian law, after Daewoong, looks broadly compatible: you may shore up an asserted effect later, but you should have asserted it — and made it plausible — at filing. File the efficacy comparison up front where you can; Daewoong is a safety net, not a substitute for a well-drafted specification. And note what the case did not do: it did not find the polymorph efficacious. It simply gave Daewoong the chance to prove what it had only claimed.
Sources & further reading: Daewoong v. Controller (judgment); Order XLI Rule 27, CPC; University of Miami v. Controller (IPAB); Novartis v. Union of India; Section 3(d).
Educational note: This case summary is general information, not legal advice.