Obviousness

Obviousness Analysis under 35 U.S.C. § 103 for US10864199

This analysis identifies combinations of prior art references that would render claims of US patent 10864199 obvious to a person having ordinary skill in the art (PHOSITA), along with the motivations for such combinations. A PHOSITA in this field would be a pharmaceutical scientist or formulation chemist with experience in developing oral dosage forms for immunosuppressants, particularly those with poor solubility and variable absorption, and familiarity with extended-release technologies and pharmacokinetic principles.

The Invention of US10864199

US10864199 describes an extended-release oral dosage form comprising tacrolimus (or an active analogue) for once-daily immunosuppressive treatment. Key aspects of the invention include:

• Release of the active substance over a very extended period, characterized by a substantial zero-order release for a majority of the release.
• Specific in vitro dissolution profile: at most 63.5% release at 12 hours, with at least 8% at 4 hours and/or at least 15% at 8 hours (using USP II paddle or USP I basket, pH 4.5, 0.005% hydroxypropylcellulose, 50 rpm).
• Improved pharmacokinetic (PK) profile compared to conventional dosage forms (e.g., Prograf®) and existing extended-release forms (e.g., Advagraf®), including:
  • Substantially extended time to reach maximal concentration (Tmax).
  • Lower maximal concentrations (Cmax).
  • Higher minimal concentrations (Cmin).
  • Extended mean residence times (MRT).
  • Surprisingly high bioavailability and excellent correlation between Cmin and bioavailability.
  • Reduced intra- and inter-subject variability in Tmax, Cmax, and AUC (0-∞) compared to Advagraf® and Prograf®.
  • Increased bioavailability (AUC(0-∞)) of at least 20% compared to Advagraf® and at least 10% compared to Prograf®.
  • Bioavailability substantially independent of dosing time.
• Reduced side effects related to high peak concentrations (e.g., nephro-/neuro-toxicity, GI side effects).
• Substantial absorption in the colon.
• Possible reduced daily dosage compared to Prograf® (e.g., 25-50% reduction) or Advagraf® (e.g., 1:0.30 to 0.75 ratio).
• The active ingredient is preferably present as a solid dispersion or solid solution in a hydrophilic or water-miscible vehicle.
• A particularly useful preparation method is controlled agglomeration (spraying a melted first composition onto a solid second carrier).

Prior Art References

The patent text references the following prior art:

• Prograf® (NDA no 50708, FDA approved April 27, 2006): A conventional, immediate-release tacrolimus formulation, administered twice daily. Known for rapid absorption (Tmax 1-2 hours), incomplete and variable bioavailability (at most about 20%), and significant inter- and intra-individual variability. It is extensively metabolized by CYP3A4 in the gut wall and liver, and associated with significant side effects including nephro- and neurotoxicity.
• Advagraf® (MR4, EMEA approved April 23, 2007): An existing commercial extended-release tacrolimus product, administered once daily. The present invention claims to provide an improved PK profile compared to Advagraf®, including decreased Cmax and increased bioavailability.
• WO 2005/020993 (by the present inventors): Demonstrated that both fast-release and slow-release tacrolimus tablets could result in improved bioavailability compared to Prograf®. This publication suggested a link between improved bioavailability and tacrolimus being in a dissolved state in the dosage form.
• WO 2005/020994 (by the present inventors): Relates to solid dispersions comprising tacrolimus, further supporting the link between improved bioavailability and the dissolved state of tacrolimus.
• WO 03/004001: Describes a method for preparing particulate material by controlled agglomeration, which the present patent explicitly identifies as a "particularly useful method" for its compositions.
• WO 00/50007 (Lipocine, Inc.): Discloses amphiphilic surfactants as suitable excipients.
• EP-A-0 184 162, EP-A-0 444 659, U.S. Pat. No. 6,387,918: Describe tacrolimus preparation and analogues.

Obviousness Combinations and Motivations

A strong argument for obviousness can be made by combining the knowledge derived from Prograf®, Advagraf®, the inventors' own prior applications (WO 2005/020993, WO 2005/020994, WO 03/004001), and general pharmaceutical formulation principles.

Combination 1: Prograf® + WO 2005/020993 + WO 2005/020994 + WO 03/004001 + General ER Knowledge

1. Motivation to develop an extended-release (ER) formulation:

   • Prograf®'s limitations: A PHOSITA would be acutely aware of Prograf®'s significant drawbacks: low and variable bioavailability, rapid Tmax (1-2 hours), the need for twice-daily (BID) dosing, and associated peak-concentration-related toxicities (nephro-, neuro-toxicity, GI side effects).
   • Patient compliance and therapeutic benefits: The motivation to convert to a once-daily (QD) regimen for improved patient compliance and to reduce dose fluctuations (lower Cmax, higher Cmin) to mitigate side effects and maintain efficacy throughout the dosing interval is a well-established objective in pharmaceutical development for drugs like tacrolimus.
   • Improved bioavailability: The inventors themselves, in WO 2005/020993, had already demonstrated that slow-release tablets could result in improved bioavailability compared to Prograf®. This explicitly points towards the viability of extended release for tacrolimus.

2. Motivation to use solid dispersions/solutions for improved bioavailability:

   • Poor solubility and metabolism: Tacrolimus is practically insoluble in water and extensively metabolized by CYP3A4 in the gut wall and liver. A PHOSITA knows that formulating poorly soluble drugs in a dissolved or finely dispersed state (e.g., solid dispersions or solutions) can significantly enhance dissolution and, consequently, bioavailability by overcoming solubility limitations.
   • Inventors' own guidance: WO 2005/020993 explicitly states that improved bioavailability might be linked to "having tacrolimus in a dissolved state". This is directly supported by WO 2005/020994 (by the same inventors), which relates to solid dispersions comprising tacrolimus and their connection to improved bioavailability. Thus, a PHOSITA would be strongly motivated by the inventors' own prior work to utilize solid dispersion technology.

3. Motivation to use controlled agglomeration for preparation:

   • Known method for solid dispersions: WO 03/004001 (also by the present inventors) details a controlled agglomeration method for preparing particulate material by spraying a melted composition onto a solid carrier. The current patent itself states this is a "particularly useful method" for its compositions, especially when tacrolimus is present as a solid dispersion. This method offers a practical and effective way to manufacture solid dispersions.

Conclusion on Obviousness of Combination 1:
A PHOSITA, faced with the known limitations of Prograf® (low bioavailability, high Cmax, BID dosing, high variability, metabolism), and informed by the inventors' own earlier work demonstrating improved bioavailability through slow-release formulations and solid dispersions of tacrolimus (WO 2005/020993, WO 2005/020994), would have a clear motivation to develop an optimized once-daily extended-release formulation. Employing the controlled agglomeration method taught in WO 03/004001 to create a solid dispersion of tacrolimus would be a logical and predictable choice for achieving enhanced dissolution and sustained release. The specific in vitro dissolution profiles and PK parameters claimed in US10864199, while precise, represent the results of routine optimization of an extended-release formulation employing known technologies (solid dispersions, matrix systems, coatings) for a drug with known absorption challenges, rather than an unpredictable invention. The goal of achieving a flatter PK profile (lower Cmax, higher Cmin, reduced swing/fluctuation) to mitigate toxicity and improve efficacy, as well as extending release to the colon to bypass upper GI metabolism, would be obvious to try with a reasonable expectation of success.

Combination 2: Advagraf® + General ER Optimization Principles

1. Motivation to improve upon Advagraf®:

   • Existing ER, but with room for improvement: Advagraf® was already an extended-release, once-daily tacrolimus product. However, the present patent explicitly highlights areas for improvement, stating it provides a "decreased Cmax value relative to that obtained by administration of the commercial product Advagraf® (MR4)... of at least about 10%... or at least about 55%" and an "increased bioavailability relative to that obtained by administration of the commercially product Advagraf® (MR4)... of at least about 20%... or at least about 65%". It also claims reduced variability compared to Advagraf®.
   • De novo patient issues: The patent notes Advagraf®'s "reduced bioavailability" in de novo transplant patients, attributing it partly to "a relative higher impact of the gastrointestinal metabolism possibly in combination with a lower absorption rate which facilitates a higher first passage extraction fraction by the liver." This would strongly motivate a PHOSITA to develop an even more extended and colon-targeting release to further bypass first-pass metabolism and improve initial exposure and predictability. The patent states that its formulation "primarily releases tacrolimus in the lower ileum and colon where metabolism is less."

2. Means for further optimization:

   • Refined extended release: A PHOSITA would routinely attempt to modify the release characteristics of an existing ER product, such as Advagraf®, to achieve better PK profiles. This involves adjusting the type and amount of matrix-forming polymers (e.g., cellulose derivatives like HPC, HPMC) or coating materials (e.g., acrylic polymers, ethylcellulose) and employing techniques like solid dispersions to ensure adequate drug release over a prolonged period, especially in the less fluid-rich environment of the colon. The selection of specific excipients to control release is within the ordinary skill in the art.
   • Targeting colon absorption: Given the known CYP3A4 metabolism in the upper GI, a PHOSITA would be motivated to design an ER formulation that delivers a substantial portion of the drug to the lower GI tract (colon) for absorption, thereby reducing metabolism and increasing bioavailability. While challenging, the concept of colon-targeting drug delivery is known.

Conclusion on Obviousness of Combination 2:
Starting from Advagraf® as an existing once-daily ER tacrolimus formulation, a PHOSITA would be motivated to further optimize its release profile to achieve superior PK benefits (lower Cmax, higher bioavailability, reduced variability, better initial exposure for de novo patients) and address the recognized limitations, particularly the impact of upper GI metabolism. The pursuit of a more extended and colon-targeted release through routine formulation adjustments and the application of known technologies like solid dispersions (as taught in WO 2005/020994) would be an obvious path with a reasonable expectation of success for improving existing ER tacrolimus therapy. The specific in vitro dissolution characteristics and achieved PK parameters, while advantageous, would likely be seen as the result of such routine optimization efforts.