New Medical Technology Series (2) – Patent Drafting Practice in the Field of Radiation Therapy (Taiwan Example)

01/31/2023

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As mentioned in the previous article, treatment of tumors in humans has become one of the most important applications of new techniques in the field of medical radiation physics. However, as researchers and developers prepare to patent new medical technologies, patent eligibility has become a critical issue. 

The patenting of medical technologies raises the ethical dilemma of whether to prioritize rewarding of researchers or protecting patients' rights to access medical resources. In fact, patent protection does provide technology researchers and developers with a period of time in which they enjoy exclusive rights as compensation or reward for the resources and effort they invested in the development of the new technology. The exclusive rights are provided as an incentive for skilled researchers to engage in R&D and to thereby advance technical innovation. However, if a patent holder’s exercise of its patent rights derived from an invention directed to a medical-related biotechnology product or method involves inappropriate restrictions or authorization, access to the patented medical product or method will be impeded, which not only violates the principle of equal human rights because economically disadvantaged patients will have difficulty accessing such medical product or method, but also has a negative impact on the maintenance of medical ethics and the allocation of medical resources, increasing burdens on social health insurance and impeding the effectiveness of public health policies.[1] This explains the reason why some countries and regions impose restrictions on the patenting of therapeutic methods.

To maximize potential across various markets, when filing patent applications, most Taiwan-based companies prioritize filing in the United States, China, Europe and the like in addition to Taiwan, as these regions have both great consumption capacity and broad markets. Many Taiwan-based companies will also consider filing in countries geographically adjacent to Taiwan, such as Japan and South Korea, or countries with considerable development potential in terms of population base, such as India and Indonesia. Given that patent laws and other regulations differ, it is necessary to adjust the drafting of claims accordingly when filing patents in multiple countries and regions.

In Taiwan, for instance, Article 24.2 of the Patent Act sets forth that “diagnostic, therapeutic and surgical methods for treatment of humans or animals” are ineligible subject matters. A detailed definition of methods for treatment of humans and animals is provided in Part II, Chapter 2, Section 2.3.2 of the Patent Examination Guidelines. In such Guidelines, methods for treatment of humans and animals are defined as methods for treating diseases or eliminating lesions in order to help living humans or animals restore or obtain health, including various methods for the purpose of treatment or with therapeutic properties, such as methods for disease prevention, methods for immunization, and methods for alleviating or reducing symptoms such as pain or loss of function. Obviously, the above definition includes the techniques for treatment of tumors.

Taiwan is not the only country to restrict the patenting of methods for treatment of humans or animals. The European Patent Convention (EPC) sets forth in Article 53, subparagraph (c) that exceptions to patentability include methods for treatment of the human or animal body by surgery or therapy and diagnostic methods practiced on humans or animals. Japan does not expressly specify the subject matters excluded from patent eligibility in the requirement of industrial applicability set forth in Article 29.1 of its Patent Act; however, it is clearly stated in Chapter 3, Section 3.1, Subsection 1 of Japan’s Patent Examination Guidelines that inventions directed to human surgical, treatment or diagnostic methods do not meet the requirement of industrial applicability. Therefore, researchers/developers of such methods are also not allowed to patent therapeutic methods in Japan.

Below, practices in Taiwan are presented as an example in order to illustrate how BNCT (Boron Neutron Capture Therapy)-related patent applications should be drafted.

Patent Drafting Practice in Taiwan

Since therapeutic methods cannot be directly defined as a patentable subject matter in Taiwan, it is currently not acceptable to write a claim directed to BNCT technology in a manner similar to “A method for treating X cancer, the method comprising irradiating (...) with a neutron beam.” Instead, a claim can only be drafted in a manner other than “a direct therapeutic method.” Taking the Taiwan Patent No. TWI762424 issued to Neuboron Therapy System LTD. as an example, the patented invention is directed to “Boron Neutron Capture Therapy System and Method for Generating Treatment Plan Therefor,” and independent claim 1 thereof reads as follows: 

1. A boron neutron capture therapy system, comprising:

a neutron beam irradiation device for generating, during irradiation therapy, a therapeutic neutron beam and irradiating a to-be-irradiated subject administered with a boron-containing drug to form a to-be-irradiated region;

a treatment plan module for performing dose simulation calculations and generating a treatment plan according to medical imaging data of the to-be-irradiated region and parameters of the therapeutic neutron beam generated by the neutron bean irradiation device, the medical imaging data of the to-be-irradiated region including tissue related information and boron concentration related information, wherein the treatment plan module establishes a corresponding 3D voxel prosthetic tissue model containing data about types of tissue according to the tissue related information, and determines the boron concentration data of each voxel unit in the 3D voxel prosthetic tissue model according to the boron concentration related information; and

a control module retrieving from the treatment plan module the treatment plan corresponding to the to-be-irradiated subject, and controlling the neutron beam irradiation device to conduct the irradiation therapy on the to-be-irradiated subject in accordance with the treatment plan, wherein the boron concentration related information includes Body Weight of the to-be-irradiated subject, Injection Dose, Measure Time of drug activity, Scan Time, radionuclide Half-Life, and Image Pixel Intensity_pixel;

the treatment plan module calculates the boron concentration of each voxel unit in the 3D voxel prosthetic tissue model according to the boron concentration related information, comprising:

calculating approximate blood Image Pixel Intensity_blood following Formula I:

wherein SUV_blood is a standard uptake value of blood, and Calibration Factor is the correction value of a medical imaging scanner;

calculating the ratio of the boron concentration of each voxel unit in the 3D voxel prosthetic tissue model to blood boron concentration following Formula II: 

wherein B_pixel represents the boron concentration of each voxel unit in the 3D voxel prosthetic tissue model, B_blood represents blood boron concentration, and SUV_pixel represents a standard uptake value of each voxel unit in the 3D voxel prosthetic tissue model;

the treatment plan module determines the boron concentration data of each voxel unit in the 3D voxel prosthetic tissue model based on the calculation results.

With reference to the recitations of the above claim, the patent applicant defines the hardware devices used in the therapy process, such as the neutron beam irradiation device, the treatment plan module and the control module, showing the specific functions performed by such devices during the therapy process by describing their uses and interactive relationships, whereby the technical components of the therapy are successfully patented in the form of an entire “therapy system.”

Additionally, in the technical fields of medical radiation physics and other new medical technologies, a newly-developed technology is unlikely to be deemed a “therapeutic method” per se, which would set such technology at the very top of the concept hierarchy (e.g., a general concept like “irradiating tumors with radioactive rays so as to destroy tumor cells.”) Rather, such a new technology is more likely to be deemed “an approach to realize” the aforesaid therapeutic method. Therefore, when a patent application is drafted, special attention must be directed to the components of the hardware devices to be used, the functions of such hardware devices, and their interactive relationships. By means of specifically defining hardware devices, the ineligibility issue facing the patenting of therapeutic methods can be overcome.

Another example can be found in independent claim 7 of the Taiwan Patent No. TWI762424. Independent claim 7 is directed to “A method for generating a treatment plan for a boron neutron capture therapy system.” An excerpt of the claim follows: 

7. A method for generating a treatment plan for a boron neutron capture therapy system, comprising:

establishing a corresponding 3D voxel prosthetic tissue model containing data about types of tissue according to tissue related information included in medical imaging data of a to-be-irradiated region;

determining boron concentration data of each voxel unit in the 3D voxel prosthetic tissue model according to boron concentration related information included in the medical imaging data of the to-be-irradiated region;

defining beam parameters in a Monte Carlo simulation program, with dose simulation calculations performed by sampling different irradiation angles;

optimizing the irradiation angles based on calculation results and generating a treatment plan, wherein the step of determining boron concentration data of each voxel unit in the 3D voxel prosthetic tissue model according to boron concentration related information included in the medical imaging data of the to-be-irradiated region comprises:

interpreting the boron concentration related information included in the medical imaging data of the to-be-irradiated region: Body Weight of the to-be-irradiated subject, Injection Dose, Measure Time of drug activity, Scan Time, radionuclide Half-Life, and Image Pixel Intensity_pixel;

calculating boron concentration of each voxel unit in the 3D voxel prosthetic tissue model, comprising:

calculating approximate blood Image Pixel Intensity_blood following Formula I, wherein SUV_blood is a standard uptake value of blood, and Calibration Factor is the correction value of a medical imaging scanner;

calculating the ratio of the boron concentration B_pixel of each voxel unit in the 3D voxel prosthetic tissue model to blood boron concentration B_blood following Formula II, wherein SUV_pixel represents a standard uptake value of each voxel unit in the 3D voxel prosthetic tissue model;

determining the boron concentration data of each voxel unit in the 3D voxel prosthetic tissue model based on the calculation results.  

In the above example, when drafting a method claim, the patent applicant focused on various physiological data and radiation data of a patient that can be obtained by instruments commonly employed in modern medicine (such as Body Weight, Injection Dose, Measure Time of drug activity, Scan Time, radionuclide Half-Life, and Image Pixel Intensity), and specific computing techniques employed by such instruments (for example, following a formula to calculate approximate blood Image Pixel Intensity, following a formula to calculate the ratio of the boron concentration of each voxel unit in the 3D voxel prosthetic tissue model to blood boron concentration, and the like), in order to obtain the boron concentration data of each voxel unit and then generate a treatment plan accordingly. Even though the final result of this “Method for generating a treatment plan” is to realize treatment as well, when the focus is shifted from the tumor patient to the processing and computing of medical data with computer software in a method claim, such a focus shift can prevent the claimed method from being classified as a therapeutic method and excluded from patent eligibility.

In addition, please be aware that in 2021, TIPO made significant amendments to Part II, Chapter 12 “Computer Software Related Inventions” of the Patent Examination Guidelines, and the new amendments provide clearer methods to help test the patent eligibility of computer software. Taking the above independent claim 7 as example, the computer software used to obtain “the boron concentration data of each voxel unit,” a key parameter of the treatment plan, is “obviously patent eligible” since it executes data processing (such as calculating the aforesaid key parameters using formulas) based on the properties of an object (such as various physiological data and radiation data of a patient).

Our next article will discuss patent drafting practices in China.