Amylin Pharmaceuticals and Exenatide Patent application became the center of an important discussion on the complexity of patent law in India, particularly in relation to inventive step, therapeutic efficacy, and objections under Section 3(d) of the Patents Act, 1970 and pharmaceutical industry. On Nov. 24, 2025, the Delhi High Court delivered a significant judgment in Case No. C.A. (COMM.IPD-PAT) 76/2022, addressing these critical issues in detail.

The dispute centered on the rejection of a patent application for a sustained-release, premixed injectable microsphere formulation containing Exenatide.

This case was filed by:

• Appellants: Amylin Pharmaceuticals, LLC & AstraZeneca Pharmaceuticals LP
• Respondent: Assistant Controller of Patents & Designs

Exenatide Patent Application Refusal Case – Background of the Case:

Amylin Pharmaceuticals filed the national phase application 1498/DELNP/2011 with Claims 1 to 32 before the Patent Office, Delhi, on May 1, 2011, based on PCT Application No. PCT/US2009/056058, claiming priority from US Patent Application No. 61/094,381 dated Sep. 4, 2008. Thereafter, the First Examination Report (FER) was issued on Mar. 29, 2017, and Amylin submitted a detailed response on Sep. 27, 2017, along with an amended set of claims. Subsequently, Amylin received a hearing notice dated Oct. 16, 2017. After the hearing, Amylin filed post-hearing written submissions along with another amended set of claims. However, the learned Controller rejected the grant of the patent application under Sections 2(1)(j) and 3(d) vide order dated Jul. 10, 2018. Amylin filed an appeal under Section 117A of the Patents Act, 1970, against the refusal order dated Jul. 10, 2018.

What Did the Applicants Invent?

The patent claimed a one-component injectable sustained-release formulation, containing:

1. A non-aqueous carrier made of triglycerides (C6–C12 fatty acids)

2. PLGA microspheres having: 1–10% (w/w) Exenatide & 0.1–5% (w/w) sugar (e.g., sucrose)

This innovation aimed to: Avoid daily injections, improve shelf-life, prevent “burst release” side effects, provide long-term stable release & simplify injection delivery

Why Was the Patent Rejected?

The Controller rejected the application under:

• Section 15: power to refuse
• Section 2(1)(ja): lack of inventive step
• Section 3(d): alleged new form of known substance without improved efficacy

The applicants appealed under Section 117A.

Exenatide Patent Application Refusal Case – Key Section Discussed:

• Section 2(1)(j): Definition of “Invention”: A product or process that is:
  • New
  • Involves an inventive step
  • Capable of industrial application
• Section 2(1)(ja): Inventive Step: Inventive step requires:
  • Technical advance over existing knowledge OR
  • Economic significance, AND
  • Must be non-obvious to a “Person Skilled in the Art” (PSITA)
• Section 3(d): Patentability Exclusion: Prevents patents for:
  • New forms of known substances
  • Unless there is significant enhancement in therapeutic efficacy
• Section 15: Controller’s Power to Refuse. The order must be:
  • Reasoned
  • Based on law and facts
  • Address applicant’s submissions
• Section 117A: Appeal to High Court. Allows appeals against decisions of the Controller.

Exenatide Patent Application Refusal Case – Arguments Presented by Amylin & AstraZeneca:

The appellants argued:

A. Controller ignored post-hearing submissions & amended claims: They claimed the order was:

• Non-speaking
• Lacking proper reasoning
• Copy-paste of their submissions

B. The invention was non-obvious:

Because:

• None of the cited prior arts (D1–D4) disclosed all features together
• Prior arts did not teach:
  • Non-aqueous carriers made of C6–C12 triglycerides
  • A pre-mixed one-component formulation
  • Specific ratios of Exenatide & sugar

C. Prior art “teaches away” from the invention

They argued:

• D1 used C18 fatty acids, not C6–C12
• D2 discouraged polymer-based microspheres
• D3 used hydrophilic carriers, unlike their hydrophobic carrier
• D4 did not relate to premixed injectable formulations

D. Controller misapplied Section 3(d)

Because:

• The invention was not a “new form” of Exenatide
• It was a new formulation with improved stability & release profile

E. Patent granted in other countries

Granted in:

• USA, Japan, Korea, Australia, China, Canada (Though foreign grants are not binding on India).

Exenatide Patent Application Refusal Case – Arguments of the Assistant Controller:

The Respondent argued:

A. Prior art D1–D4 disclosed all elements

• D1: PLGA microspheres in oil-based carriers
• D2: Exenatide + sugars for stability
• D3: Injectable PLGA microspheres in non-aqueous carriers
• D4: Sustained-release PLGA microspheres containing polypeptides & sugars

B. Combining D1 and D2 was obvious

• A PSITA could:
  • Take Exenatide + sugar premix from D2
  • Insert into PLGA microspheres disclosed in D1

C. Adjusting concentrations is routine experimentation:

• 2% sucrose or 5% Exenatide was considered obvious optimization.

D. Section 3(d) applies Because:

• Exenatide is a known substance
• No significant improvement in therapeutic efficacy was shown

E. Foreign grants not relevant

• Indian patentability standards differ.

Exenatide Patent Application Refusal Case – Court’s Step-by-Step Analysis:

The Court followed the inventive step analysis laid out in:

• Hoffmann-La Roche v. Cipla (2016)
• AstraZeneca v. Torrent (2020)
• Bristol-Myers v. BDR (2020)

Amylin Pharmaceuticals vs. Assistant Controller of Patents – What Each Prior Art Disclosed?

Technical Feature	D1	D2	D3	D4
Non-aqueous carrier	Yes (oils) but not C6–C12	No	No	No
Exenatide	No	Yes	No	Yes (Exendin-4)
Sugar (e.g., sucrose)	Yes	Yes	No	Yes
PLGA Microspheres	Yes	No	Yes	Yes

The Court observed:

• No single prior art disclosed the entire claimed combination
• But PSITA could combine D1 + D2 + D3 using routine knowledge

Exenatide Patent Application Refusal Case – Court’s Conclusions on Key Issues:

A. On “Non-Aqueous Carrier”

Court held:

• D1 suggests using fixed oils
• “Fixed oils” normally mean triglycerides
• Hence PSITA could consider triglycerides including C6–C12

This weakens the applicant’s non-obviousness argument.

B. On Use of Exenatide + Sugar

• Already disclosed in D2 and D4
• Concentration ranges (1–10% Exenatide, 0.1–5% sugar) are routine optimizations

C. On PLGA Microspheres

• D1 and D3 both disclose PLGA microsphere systems
• Long-acting formulations are known

D. On Section 3(d)

The Court noted:

• Applicants failed to show improved therapeutic efficacy
• Stability/shelf-life is not equal to therapeutic efficacy
• Hence Section 3(d) objection was not overcome

E. On Reasoning in Controller’s Order

The Court criticized:

• Repetition of applicant’s submissions
• Lack of independent reasoning

Exenatide Patent Application Refusal Case – Final Outcome:

The Court ultimately held that:

• The claimed formulation was obvious in light of combined prior art
• No surprising technical effect was demonstrated
• Section 3(d) objection sustained
• Appeal dismissed; Controller’s rejection upheld

Exenatide Patent Application Refusal Case – Key Takeaways:

• Combination formulations must show a real technical advance. Simply rearranging known elements rarely succeeds.
• Stability or shelf-life improvement ≠ therapeutic efficacy. For Section 3(d), efficacy must relate to therapeutic impact, not formulation convenience.
• Inventive step requires clear evidence of non-obviousness. Comparative data, unexpected results, or unique mechanisms help.
• Controller’s order must be reasoned. But minor defects will not save an otherwise invalid patent.
• Foreign patent grants do not influence Indian law. India applies its own standards, focusing heavily on Sections 3(d) and 2(1)(ja).

Exenatide Patent Application Refusal Case – Conclusion:

This Delhi High Court judgment is an important reference for innovators submitting pharmaceutical formulation patents in India. The decision reinforces that:

• Indian patent law applies a strict inventive step standard.
• Section 3(d) acts as a strong filter against incremental pharmaceutical innovations.
• Applicants must provide clear, robust experimental data showing unexpected advantages.