Obviousness

Obviousness Analysis under 35 U.S.C. § 103 for US12115233

The US patent 12115233, titled "Imaging and radiotherapeutics agents targeting fibroblast-activation protein-α (FAP-α)," claims a compound of Formula (I) (B-L-A), pharmaceutical compositions thereof, and methods for imaging and treating FAP-α-related diseases [cite: Original patent text]. An analysis of the patent's own disclosure and cited prior art suggests that these claims may be rendered obvious under 35 U.S.C. § 103 to a person having ordinary skill in the art (POSITA).

Core Claim: Compound of Formula (I) (B-L-A)

Independent Claim 1 defines a compound of the general structure B-L-A, where 'A' is a targeting moiety for FAP-α, 'B' is any optical or radiolabeled functional group for imaging or therapy, and 'L' is a linker [cite: Original patent text]. The obviousness of this compound relies on the prior art demonstrating: (1) a clear motivation to target FAP-α, (2) the existence of suitable FAP-α targeting moieties ('A'), (3) the availability of appropriate functional groups ('B'), and (4) an established methodology for linking such components ('L') to form a B-L-A construct.

1. Motivation to Target FAP-α

The patent itself clearly establishes FAP-α as a highly relevant biological target for both imaging and therapy. The background section notes that "FAP-α expression has been detected on the surface of fibroblasts in the stroma surrounding >90% of the epithelial cancers examined," including breast, colorectal, skin, prostate, and pancreatic cancers [cite: Original patent text]. It also states that FAP-α is a characteristic marker for carcinoma-associated fibroblasts (CAF), which play a critical role in promoting tumor growth and survival [cite: Original patent text]. Furthermore, FAP-α is expressed in areas of chronic inflammation, arthritis, and fibrosis [cite: Original patent text]. The patent concludes that "These characteristics make FAP-α a potential imaging and radiotherapeutic target for cancer and inflammation diseases" [cite: Original patent text]. This explicit recognition in the prior art provides a strong and undeniable motivation for a POSITA to develop agents targeting FAP-α for diagnostic and therapeutic purposes.

2. FAP-α Targeting Moiety ('A')

The patent acknowledges that anti-FAP antibodies (e.g., murine F19, sibrotuzumab, ESC11, ESC14) had already been investigated for radioimmunotargeting of malignancies and imaging inflammation [cite: Original patent text]. While noting their pharmacokinetic limitations, this demonstrates that FAP-α could be effectively targeted. Crucially, the patent explicitly lists several prior art references disclosing low-molecular-weight (LMW) inhibitors selectively targeting FAP-α [cite: Original patent text]:

• Lo, et al., 2009
• Tsai, et al., 2010
• Ryabtsova, et al., 2012
• Poplawski, et al., 2013
• Jansen, et al., 2013
• Jansen, et al., 2014

These references would have provided a POSITA with a selection of potent and selective LMW FAP-α inhibitors suitable for use as the 'A' targeting moiety. The patent even states that "the presently disclosed subject matter provides potent and selective low-molecular-weight (LMW) ligands of FAP-α, i.e., an FAP-α selective inhibitor, conjugated with a targeting moiety feasible for modification with optical dyes and radiolabeling groups" [cite: Original patent text], implying that the inhibitor part (the 'A' moiety) itself was a known selective inhibitor.

3. Functional Group ('B')

The 'B' moiety is broadly defined as "any optical or radiolabeled functional group suitable for optical imaging, PET imaging, SPECT imaging, or radiotherapy" [cite: Original patent text]. The patent lists numerous specific examples of radionuclides for PET and SPECT imaging (e.g., ⁶⁸Ga, ⁶⁴Cu, ¹⁸F, ¹¹¹In, ⁹⁹mTc) and radiotherapy (e.g., ⁹⁰Y, ¹⁷⁷Lu, ¹³¹I, ²²⁵Ac) [cite: Original patent text]. It also lists various optical dyes (e.g., carbocyanine, indocarbocyanine, IRDye 800CW) [cite: Original patent text]. These are standard, well-known agents in the field of molecular imaging and radiotherapy, and their selection would be a routine choice for a POSITA based on the desired application. Table 1, for instance, provides "Representative Therapeutic Radionuclides" that were part of the general knowledge.

4. Linker ('L') and Motivation to Combine

The most significant teaching for obviousness of the B-L-A construct comes from the patent's own citations regarding suitable linkers. The patent explicitly references and incorporates by reference two U.S. Patent Application Publications by Pomper et al. [cite: Original patent text]:

• U.S. Patent Application Publication No. US2011/0064657 A1, titled "Labeled Inhibitors of Prostate Specific Membrane Antigen (PSMA), Biological Evaluation, and Use as Imaging Agents" [cite: Original patent text].
• U.S. Patent Application Publication No. US2012/0009121 A1, titled "PSMA-Targeting Compounds and Uses Thereof" [cite: Original patent text].

These Pomper et al. references teach the direct analogy of conjugating a small molecule inhibitor of a cell surface peptidase (Prostate Specific Membrane Antigen, PSMA) to an imaging or therapeutic agent via a linker. PSMA, like FAP-α, is a cell surface protease relevant in cancer. The Pomper et al. patents demonstrate the well-known strategy of creating a B-L-A type construct for diagnostic and therapeutic applications on an analogous enzyme target. The current patent explicitly states that linkers from these publications are "Suitable linkers" for its own compounds [cite: Original patent text]. This constitutes a direct teaching and suggestion to use such linkers and the overall B-L-A conjugation strategy.

A POSITA, motivated to overcome the limitations of antibody-based FAP-α targeting (slow clearance, non-specific uptake) by using LMW agents (as also discussed in the patent's background [cite: Original patent text]), would find a clear blueprint in the Pomper et al. references. Given the existence of known LMW FAP-α inhibitors (Lo, Tsai, Ryabtsova, Poplawski, Jansen) for the 'A' component, and the routine selection of 'B' moieties (radionuclides/optical dyes), a POSITA would have a reasonable expectation of success in adapting the established B-L-A conjugation strategy from the PSMA field to FAP-α. This involves taking a known LMW FAP-α inhibitor, selecting a known linker (as explicitly taught by Pomper et al.), and attaching a known diagnostic or therapeutic moiety. This combination would lead directly to the claimed compound of Formula (I).

Obviousness of Dependent Claims

If the compound of Formula (I) (Claim 1) is obvious, then the dependent claims would also be rendered obvious:

• Claim 2 (Pharmaceutical Composition): A pharmaceutical composition comprising an obvious compound of Formula (I) in admixture with a pharmaceutically acceptable carrier, diluent, excipient, or adjuvant is a routine formulation step for a POSITA [cite: Original patent text].
• Claim 3 (Method for Imaging Disease): Administering an obvious compound of Formula (I) (with an optical or radiolabeled 'B' for imaging) and obtaining an image, for diseases associated with FAP-α, directly flows from the well-known utility of such agents and the motivation to image FAP-α [cite: Original patent text].
• Claim 4 (Method for Inhibiting FAP-α): Administering an effective amount of an obvious FAP-α targeting compound of Formula (I) to inhibit FAP-α is an inherent utility of an FAP-α inhibitor, and thus obvious [cite: Original patent text].
• Claim 5 (Method for Treating FAP-α-related Disease): Administering an effective amount of an obvious compound of Formula (I) (with a radiolabeled 'B' for radiotherapy) to treat FAP-α-related diseases is a direct application of a therapeutic agent targeting a known disease marker [cite: Original patent text].

Conclusion

Based on the patent's own disclosure, a POSITA would have been motivated to combine known LMW FAP-α inhibitors with established conjugation methodologies for creating targeted imaging and therapeutic agents. The explicit teaching of suitable linkers and the B-L-A construct in the PSMA-targeting prior art (Pomper et al.) makes the claimed invention, particularly the compound of Formula (I) and its uses, an obvious extension of existing knowledge in the field.