Obviousness

Obviousness Analysis of US Patent 11,123,331 under 35 U.S.C. § 103

This analysis assesses the obviousness of US Patent 11,123,331, titled "Tacrolimus for improved treatment of transplant patients," under 35 U.S.C. § 103, based on the provided patent text and a priority date of May 30, 2007.

1. The Claimed Invention

US Patent 11,123,331 claims an extended-release oral dosage form of tacrolimus for once-daily immunosuppressive treatment. Key features, as inferred from the abstract and detailed description, include:

• A specific in vitro release profile, characterized by releasing at most 63.5% of the active substance at the 12-hour mark, and at least 8% at 4 hours and/or at least 15% at 8 hours, when tested under defined USP dissolution conditions (paddle/basket, pH 4.5, 0.005% hydroxypropylcellulose, 50 rpm).
• Improved pharmacokinetic properties in vivo compared to conventional (Prograf®) and existing extended-release (Advagraf®/MR4) tacrolimus formulations, specifically:
  • Decreased intra- and inter-subject variability of mean blood Tmax, Cmax, and AUC(0-infinity) by at least 10% compared to Advagraf®.
  • Decreased Cmax value by at least 10% compared to Advagraf®.
  • Increased bioavailability (AUC(0-infinity)) by at least 20% compared to Advagraf®.
  • Reduced swing ((Cmax-Cmin)/Cmin) and fluctuation ((Cmax-Cmin)/Caverage) compared to Advagraf® or Prograf®.
  • Increased mean residence time (MRT) by at least 10% compared to Advagraf® and at least 35% compared to Prograf®.
  • A longer time to reach Tmax and a higher Cmin.
• Improved systemic exposure on Day 1 for de novo liver/kidney transplant patients compared to other formulations.
• Bioavailability that is substantially independent of the time of day administered, suitable for bedtime dosing.
• A specific composition where tacrolimus is dissolved or dispersed as a solid dispersion or solid solution in a hydrophilic or water-miscible vehicle (e.g., polyethylene glycols, poloxamers).
• Methods of treatment using this dosage form, including for de novo patients and conversion from other tacrolimus regimens with specific dose ratios.

2. Closest Prior Art and Pertinent Prior Art

The patent itself identifies several relevant prior art references:

• Prograf®: An immediate-release tacrolimus formulation, approved by the FDA in 1994, characterized by large inter- and intra-individual variability in absorption, incomplete and variable bioavailability (at most about 20%), and significant side effects. [cite: "Tacrolimus administered as Prograf® capsules, exhibits a large inter- and intra-individual variability of its absorption and metabolism.", "the bioavailability is generally as low as at the most about 20% after oral administration.", "Tacrolimus is known to induce significant side effects, of nephro- or neuro-toxic origin, as well as GI side-effects and others."] It required twice-daily dosing and frequent dose adjustments. [cite: "the recommended dosage range for Prograf® is 0.1 to 0.2 mg/kg/day given every 12 hours in two divided doses. Importantly, the blood levels have to be monitored."]
• Advagraf® (also known as MR4): An extended-release tacrolimus formulation, approved by the EMEA on April 23, 2007. [cite: "Tacrolimus also known as FK-506 or FR-900506, is the active ingredient of Prograf®, Protopic®, and Advagraf® approved by the European Agency for the Evaluation of Medicinal Products (EMEA) at 23 Apr. 2007."] This product provided once-daily dosing. The present patent explicitly distinguishes itself by demonstrating improved pharmacokinetic parameters (e.g., decreased variability, decreased Cmax, increased bioavailability) compared to Advagraf®. It also notes that Advagraf® provided lower systemic exposure in de novo transplant patients on Day 1 compared to Prograf®. [cite: "Advagraf® in the first 24 hours provides a systemic exposure which is approximately 30% and 50% lower when compared with administration of the Prograf® formulation administered to de novo kidney and de novo liver transplant patients, respectively."]
• WO 2005/020993 A1 (priority date February 28, 2005): A patent application by the same inventors, which tested different tacrolimus formulations, including fast and slow-release tablets, demonstrating that both could result in improved bioavailability compared with Prograf®. [cite: "Inventors of the present application have in the patent application WO 2005/020993 also tested different formulations of tacrolimus in Beagle dogs and minipigs, however demonstrating that both a fast release tablet (Example 18) and a slow release tablet (Example 19) can result in improved bioavailability compared with Prograf®."]
• WO 2005/020994 A1 (priority date February 28, 2005): Another patent application by the same inventors, which linked improved bioavailability of tacrolimus to having the drug in a dissolved state and related to solid dispersions comprising tacrolimus. [cite: "This indicates that an improved bioavailability could be linked to having tacrolimus in a dissolved state in the dosage form which also appears from WO 2005/020994 by the same inventors relating to solid dispersions comprising tacrolimus."] This document explicitly discusses hydrophilic or water-miscible vehicles like polyethylene glycols and poloxamers for solid dispersions. [cite: "useful hydrophilic or water-miscible vehicles are selected from the group consisting of polyethylene glycols, polyoxyethylene oxides, poloxamers, polyoxyethylene stearates, poly-epsilon caprolactone, polyglycolized glycerides such as Gelucire®, and mixtures thereof."]

3. Obviousness Combinations and Motivation to Combine

A Person of Ordinary Skill in the Art (POSITA) in pharmaceutical formulation and transplantation medicine, at the time of the invention (before May 30, 2007), would have been well aware of the significant challenges associated with tacrolimus therapy, particularly the high variability, the need for frequent monitoring and dose adjustments with Prograf®, and its associated toxicities. The introduction of Advagraf® demonstrated the feasibility and desirability of a once-daily extended-release formulation. However, as acknowledged by the present patent, Advagraf® still presented limitations, especially regarding initial systemic exposure in de novo transplant patients and opportunities for further reducing pharmacokinetic variability.

Combination 1: Advagraf® in view of WO 2005/020994 A1

• Advagraf® taught the concept of a once-daily, extended-release oral tacrolimus dosage form for immunosuppression.
• WO 2005/020994 A1, by the same inventors of US11123331, explicitly taught that improved bioavailability of tacrolimus could be achieved by formulating it in a dissolved state, specifically as a solid dispersion using hydrophilic or water-miscible vehicles such as polyethylene glycols and poloxamers. [cite: "This indicates that an improved bioavailability could be linked to having tacrolimus in a dissolved state in the dosage form which also appears from WO 2005/020994 by the same inventors relating to solid dispersions comprising tacrolimus."]

Motivation to Combine: A POSITA would have been highly motivated to combine these teachings. The inherent poor and variable bioavailability of tacrolimus (as seen with Prograf®) was a well-known problem. While Advagraf® offered an extended-release, once-daily solution, its limitations (as noted in US11123331, e.g., for de novo patients) would prompt further development. WO 2005/020994 A1 provided a clear technical approach to enhance tacrolimus's bioavailability through solid dispersions. It would have been obvious to a POSITA to incorporate the solid dispersion technology taught in WO 2005/020994 A1 into an extended-release platform, such as the one exemplified by Advagraf®, to further improve the bioavailability and pharmacokinetic profile (e.g., reduce variability, maintain more stable blood levels, potentially reduce Cmax, and increase AUC and MRT) of once-daily tacrolimus. The use of known excipients like PEGs and poloxamers for forming such solid dispersions, as explicitly mentioned in WO 2005/020994 A1, would have been a routine choice for a formulator.

The resulting combined formulation would naturally be expected to exhibit an optimized dissolution profile and improved in vivo pharmacokinetic parameters, including those claimed in US11123331 (e.g., lower variability, reduced Cmax, higher AUC, and longer MRT). Achieving specific numerical ranges for these parameters through formulation optimization, while requiring experimentation, would be considered within the realm of routine development for a POSITA pursuing improved extended-release tacrolimus formulations using established principles of drug delivery and bioavailability enhancement. The patent itself notes that "the release may be carefully tailored to level out several counteracting factors" in the GI tract, indicating that tailoring release profiles is a known objective for formulators. [cite: "the release may be carefully tailored to level out several counteracting factors of. These factors includes in the colon a lower area for absorption, a lower content of fluids, higher content of solids, bacterial degradation, higher impact from the P-glycoprotein transporter system, lower motility, differences in mucosal barrier and/or mucous composition and differences in pH along the colon compared with the small intestines."]

Reinforcement by WO 2005/020993 A1:

WO 2005/020993 A1 further strengthens the obviousness argument by explicitly demonstrating, prior to the priority date of US11123331, that "slow release" tacrolimus tablets could result in improved bioavailability compared to Prograf®. [cite: "Inventors of the present application have in the patent application WO 2005/020993 also tested different formulations of tacrolimus in Beagle dogs and minipigs, however demonstrating that both a fast release tablet (Example 18) and a slow release tablet (Example 19) can result in improved bioavailability compared with Prograf®."] This reinforces the motivation for a POSITA to pursue extended-release formulations for improved bioavailability and indicates a clear research direction already undertaken by the inventors themselves.

Therefore, a combination of Advagraf® (or its equivalent MR4), WO 2005/020993 A1, and WO 2005/020994 A1 would make the claims of US11123331 obvious. Advagraf® established the goal of an extended-release, once-daily tacrolimus. WO 2005/020993 A1 showed the benefit of slow-release tacrolimus on bioavailability. WO 2005/020994 A1 provided the specific technical means (solid dispersions with hydrophilic vehicles) to achieve improved bioavailability. A POSITA would have been motivated to combine these elements to develop a more effective and consistent once-daily extended-release tacrolimus formulation, with a reasonable expectation of achieving the improved pharmacokinetic profiles and therapeutic advantages described in US11123331.

4. Secondary Considerations

The patent discusses several advantages, such as "surprisingly high bioavailability," "significant reduction in side effects," "decreased dosage," and "substantial reduced peak concentrations." While these are strong indicators of non-obviousness, they must be weighed against the strength of the prima facie case of obviousness. Given that the inventors themselves had previously published WO 2005/020993 A1 and WO 2005/020994 A1, which already pointed towards improving tacrolimus bioavailability through controlled release and solid dispersions, the further improvements, even if significant, might be seen as the expected outcome of continued, albeit successful, optimization along an established and obvious path. The problems addressed, such as high variability and side effects of Prograf®, were long-felt needs, but Advagraf® had already begun to address them with an extended-release formulation, suggesting that the invention represents an incremental improvement rather than a solution to a completely unsolved problem.