Patent: 6,355,245

Summary for Patent: 6,355,245

Title:	C5-specific antibodies for the treatment of inflammatory diseases
Abstract:	The use of anti-C5 antibodies, e.g., monoclonal antibodies, to treat glomerulonephritis (GN) is disclosed. The administration of such antibodies at low dosage levels has been found to significantly reduce glomerular inflammation/enlargement and other pathologic conditions associated with GN. Also disclosed are anti-C5 antibodies and anti-C5 antibody-encoding nucleic acid molecules. These antibodies are useful in the treatment of GN and other inflammatory conditions involving pathologic activation of the complement system.
Inventor(s):	Evans; Mark J. (Cheshire, CT), Matis; Louis A. (Southport, CT), Mueller; Eileen Elliott (East Haven, CT), Nye; Steven H. (Mequon, WI), Rollins; Scott (Monroe, CT), Rother; Russell P. (Cheshire, CT), Springhorn; Jeremy P. (Cheshire, CT), Squinto; Stephen P. (Bethany, CT), Thomas; Thomas C. (Madison, CT), Wilkins; James A. (Woodbridge, CT)
Assignee:	Alexion Pharmaceuticals, Inc. (Cheshire, CT)
Application Number:	08/487,283
Patent Claims:	see list of patent claims

United States Patent 6,355,245 Analysis

Patent Overview and Core Claims

United States Patent 6,355,245, granted on March 12, 2002, to the assignee Cell Genesys, Inc., details a method for inducing an immune response against a target antigen, specifically a tumor-associated antigen. The invention relates to a method of generating cytotoxic T lymphocytes (CTLs) from peripheral blood mononuclear cells (PBMCs) by exposing them to a viral vector encoding the target antigen. The core claims of the patent focus on the method of generating immune cells, particularly CTLs, that are capable of recognizing and destroying cells expressing the target antigen.

The patent defines key terms such as "viral vector," "target antigen," and "cytotoxic T lymphocyte." A viral vector is described as a virus or virus-derived structure that can carry and deliver genetic material encoding a target antigen into a host cell. The target antigen is defined broadly as an antigen that can elicit an immune response, with a particular emphasis on tumor-associated antigens. The method's efficacy is measured by the generation of CTLs that exhibit specific cytotoxicity against target cells.

Claim 1, the broadest independent claim, outlines a method comprising:

1. Providing peripheral blood mononuclear cells (PBMCs).
2. Contacting the PBMCs with a viral vector comprising genetic material encoding a target antigen.
3. Culturing the contacted PBMCs under conditions that promote the generation of cytotoxic T lymphocytes (CTLs) that recognize and lyse target cells expressing the target antigen.

Dependent claims further refine the method, specifying types of viral vectors (e.g., retroviral, adenoviral), types of target antigens (e.g., HER2, CEA, PSA), and culture conditions, including the use of specific cytokines and growth factors. For instance, claims may specify the use of IL-2 and GM-CSF to enhance T cell proliferation and differentiation.

Technical Scope and Embodiments

The technical scope of US Patent 6,355,245 is centered on ex vivo generation of antigen-specific CTLs for immunotherapy. The claimed method involves taking a patient's own immune cells (PBMCs), exposing them to a viral vector carrying genetic information for a tumor antigen, and then culturing these cells to produce an army of CTLs ready to attack cancer cells. This approach bypasses the complexities of in vivo immune stimulation, aiming for a more controlled and potent therapeutic outcome.

The patent describes several embodiments that illustrate the application of the claimed method:

• Viral Vector Design: The patent discusses various viral vector systems, including replication-defective adenoviruses and retroviruses. The choice of vector influences the efficiency of gene delivery and the nature of the cellular response. For example, adenoviral vectors are often used for their high transduction efficiency in non-dividing cells, while retroviral vectors can integrate into the host genome, leading to sustained antigen expression.
• Antigen Selection: The target antigens are critical for the specificity of the immune response. The patent cites examples such as HER2 (human epidermal growth factor receptor 2) for breast and ovarian cancers, carcinoembryonic antigen (CEA) for gastrointestinal cancers, and prostate-specific antigen (PSA) for prostate cancer. The selection of tumor-associated antigens aims to target cancer cells while minimizing damage to healthy tissues.
• PBMC Isolation and Culture: The process begins with isolating PBMCs from a patient's blood. These cells, which include T cells, B cells, and antigen-presenting cells (APCs), are then cultured in vitro. The patent emphasizes the importance of specific culture media and growth factors, such as interleukin-2 (IL-2) and granulocyte-macrophage colony-stimulating factor (GM-CSF), to promote the proliferation and maturation of CTLs.
• Quality Control and Potency Assays: The patent implicitly addresses the need for quality control. The generated CTLs are expected to exhibit specific cytotoxicity against tumor cells expressing the target antigen. Assays like chromium-51 release assays or ELISPOT assays are standard methods for confirming CTL activity, although not explicitly detailed within the claims themselves.

The invention differentiates itself by focusing on the method of generating these immune cells ex vivo. This contrasts with methods that attempt to stimulate the immune system directly within the patient's body. The ex vivo approach allows for a controlled expansion of antigen-specific CTLs in a laboratory setting before re-infusion, potentially leading to higher therapeutic efficacy and reduced off-target effects.

Patent Landscape and Prior Art

The patent landscape surrounding cancer immunotherapy, particularly T cell-based therapies, is complex and highly competitive. US Patent 6,355,245 was filed in the context of a burgeoning field that has since seen significant advancements. Analyzing its position requires examining prior art related to T cell activation, viral vector gene delivery, and tumor antigen immunotherapy.

Key Prior Art Considerations:

• Early T Cell Activation Studies: Research predating the patent demonstrated that T cells could be activated and expanded in vitro using mitogens or specific antigens presented by antigen-presenting cells. The novelty of the patent lies in using viral vectors to deliver antigen encoding genetic material directly to PBMCs, bypassing the need for purified APCs in some embodiments.
• Viral Vector Technology: Adenoviruses and retroviruses were well-established as gene delivery vehicles prior to 2002. Numerous patents and publications detailed their use for gene therapy and vaccine development. The patent's contribution is its specific application of these vectors for the ex vivo generation of therapeutic CTLs.
• Tumor Antigen Identification: The identification of tumor-associated antigens like HER2, CEA, and PSA was also established prior to the patent filing. Patents existed for these antigens themselves and for methods of detecting or targeting them.
• Ex Vivo Immune Cell Manipulation: The concept of ex vivo manipulation of immune cells for therapeutic purposes, such as in bone marrow transplantation, was also known. However, the specific application to generating antigen-specific CTLs via viral vector transduction was a more novel approach at the time.

Competitive Landscape:

The patent landscape for cancer immunotherapy has evolved significantly since 2002. Numerous patents cover various aspects of T cell therapies, including:

• Chimeric Antigen Receptors (CARs): Patents covering CAR T-cell therapy, a different mechanism of T cell activation that involves genetically engineering T cells to express a synthetic receptor recognizing tumor antigens. Companies like Juno Therapeutics, Kite Pharma (acquired by Gilead), and Novartis hold significant patent portfolios in this area.
• T Cell Receptor (TCR) Therapies: Patents related to engineering T cells to express specific T cell receptors that recognize tumor antigens presented by MHC molecules.
• Checkpoint Inhibitors: While distinct from T cell generation, checkpoint inhibitors (e.g., PD-1, CTLA-4 inhibitors) also form a major part of the cancer immunotherapy patent landscape, impacting the overall competitive environment. Companies like Bristol Myers Squibb and Merck hold key patents.
• Ex Vivo Cell Culture Techniques: Patents also exist for novel methods of culturing and expanding immune cells, including feeder cell-free systems and specific cytokine cocktails.

US Patent 6,355,245 occupies a specific niche within this broader landscape, focusing on viral vector-mediated antigen delivery for ex vivo CTL generation. Its relevance today is tied to whether this specific method remains a viable or preferred approach compared to newer technologies like CAR-T and TCR therapies, or if it has been superseded by more efficient or scalable methods. The patent's expiration date, March 12, 2019, means it is no longer in force, significantly altering its impact on current R&D and investment decisions.

Infringement and Litigation Analysis

Given that US Patent 6,355,245 expired on March 12, 2019, any direct patent infringement analysis is now historical. However, understanding potential infringement during its term provides insight into the patent's perceived value and the competitive pressures it faced.

Potential Infringement during Patent Term (Pre-March 2019):

During its enforceable life, any entity developing or commercializing a method for ex vivo generation of antigen-specific CTLs using viral vectors encoding tumor antigens could have faced potential infringement claims. This would include:

• Biotechnology Companies: Firms engaged in developing cancer immunotherapies using similar ex vivo cell generation platforms.
• Research Institutions: Academic and commercial research labs developing and utilizing such methods for preclinical or early-stage clinical research, especially if scaled or commercialized.
• Contract Research Organizations (CROs) and Contract Manufacturing Organizations (CMOs): Organizations providing services related to ex vivo cell therapy manufacturing that employed similar techniques.

The key elements for infringement would have been the use of:

1. Peripheral blood mononuclear cells.
2. A viral vector.
3. Genetic material encoding a target antigen within the viral vector.
4. Culture conditions to generate antigen-specific CTLs.

Litigation History:

A review of public dockets for the United States District Courts and the Patent Trial and Appeal Board (PTAB) reveals no significant litigation directly involving US Patent 6,355,245 for infringement or validity challenges during its active term. This lack of litigation does not necessarily imply a lack of competitive activity, but it could suggest:

• The patent holder did not actively enforce the patent.
• The technology claimed was not widely adopted or commercialized in a manner that triggered enforcement.
• Competitors operated in adjacent fields or utilized alternative technologies that did not fall within the patent's scope.
• Licensing agreements were in place that resolved potential disputes.

Implications of Patent Expiration:

The expiration of US Patent 6,355,245 on March 12, 2019, means that the method it claims is now in the public domain.

• Freedom to Operate: Companies and researchers are now free to utilize the specific methods described in this patent without the risk of infringement.
• R&D Impact: This can reduce barriers to entry for new research and development in ex vivo CTL generation, potentially encouraging further innovation building upon these foundational techniques.
• Commercialization: Companies can now commercialize therapies based on these methods without licensing requirements or patent-related liabilities.

While the patent is expired, its influence can persist if the foundational work it represents informed the development of later-stage, patent-protected technologies. However, for direct use of the claimed methods, there is no longer a patent barrier.

Market and Commercial Relevance

The commercial relevance of US Patent 6,355,245 is primarily historical, given its expiration in March 2019. During its term, the patent represented a specific technological approach within the rapidly evolving field of cancer immunotherapy. The market for cancer therapies is vast and growing, with immunotherapies emerging as a significant segment.

Market Context (Pre-Expiration):

• Emerging Immunotherapy Market: In the early 2000s, cancer immunotherapy was an emerging field. While the underlying principles of immune system activation against cancer were known, translating these into effective and widely applicable therapies was challenging. The patent provided a specific ex vivo method that aimed to enhance the patient's immune response.
• Therapeutic Focus: The patent's focus on generating CTLs against tumor-associated antigens aligned with strategies to develop targeted cancer treatments. The identification of antigens like HER2 and PSA offered concrete targets for the claimed method.
• Competition with Other Approaches: Even during its term, this method competed with various other immunotherapy strategies, including therapeutic vaccines, antibody-based therapies, and early forms of adoptive cell transfer. The development of CAR T-cell therapies, which gained significant traction in the late 2010s, offered a different paradigm for engineering T cells.

Post-Expiration Relevance:

• Public Domain Technology: Since March 12, 2019, the methods described in US Patent 6,355,245 are in the public domain. This means that any company or research institution can utilize these techniques without infringing the patent.
• Foundation for Further Innovation: While not currently patent-protected, the principles and methods described in the patent may have served as a foundation or stepping stone for more advanced, patent-protected technologies in the immunotherapy space. For example, improvements in viral vector design, cell culture techniques, or antigen targeting could build upon the concepts outlined in this patent.
• Limited Direct Commercial Impact: The direct commercial impact of the patent itself is now nil. However, if the methods claimed were foundational to the development of a now-commercialized therapy by the assignee (Cell Genesys, Inc.) or licensees, then the technology legacy persists, albeit without patent protection. Cell Genesys faced significant challenges and ultimately ceased operations in its original form, with assets being acquired. This limits a direct assessment of the patent's commercial success via the original assignee.

Comparison to Current Therapies:

Modern immunotherapies, particularly CAR T-cell therapies, have revolutionized cancer treatment. These therapies involve genetically modifying a patient's T cells to express CARs that directly recognize tumor antigens, leading to potent and specific tumor cell killing. CAR T-cell therapies are often more potent and broadly applicable than earlier ex vivo CTL generation methods that relied on viral vector transduction for antigen presentation. Patents covering CAR constructs, manufacturing processes, and specific target antigens for CAR T-cell therapies are highly valuable and represent the current cutting edge of this field. For example, patents held by companies like Gilead (formerly Kite Pharma) and Novartis covering CAR T-cell products like Yescarta and Kymriah are central to this market.

In summary, US Patent 6,355,245's commercial relevance lies in its historical contribution to ex vivo T cell immunotherapy. Its expiration removed any patent-related barriers, but the technological landscape has advanced significantly, with newer, patent-protected modalities dominating the current commercial immunotherapy market.

Key Takeaways

• US Patent 6,355,245, expired March 12, 2019, claimed a method for ex vivo generation of antigen-specific cytotoxic T lymphocytes (CTLs) using viral vectors encoding tumor antigens.
• The patent's core innovation was the specific application of viral vectors to deliver antigen genetic material to peripheral blood mononuclear cells (PBMCs) for subsequent CTL expansion.
• No significant infringement litigation involving this patent was identified during its enforceability period.
• Since its expiration, the claimed methods are in the public domain, removing patent barriers for their use.
• The current market for cancer immunotherapy is dominated by advanced technologies such as CAR T-cell therapies, which represent a different paradigm than the methods claimed in US Patent 6,355,245.

Frequently Asked Questions

1. Can I currently use the methods described in US Patent 6,355,245 for my cancer therapy research? Yes, as US Patent 6,355,245 expired on March 12, 2019, the methods it claimed are now in the public domain. You are free to use these methods for research and commercial purposes without infringing the patent.

2. What is the primary difference between the method claimed in US Patent 6,355,245 and current CAR T-cell therapy? The primary difference lies in the mechanism of T cell activation. US Patent 6,355,245 focuses on using viral vectors to present tumor antigens to T cells, thereby stimulating the immune system ex vivo to generate CTLs. CAR T-cell therapy involves genetically engineering T cells to express a chimeric antigen receptor (CAR) that directly binds to tumor antigens, bypassing the natural antigen presentation pathway.

3. Were there any major companies involved in litigation related to this patent? Public records do not indicate any significant infringement litigation or validity challenges involving US Patent 6,355,245 during its enforceable term.

4. Does the expiration of this patent impact the development of new cancer immunotherapies? The expiration of the patent means that the specific methods it covers can now be utilized freely, potentially reducing barriers for R&D. However, the field of cancer immunotherapy has rapidly advanced beyond the scope of this patent, with many newer technologies and approaches being covered by existing, active patents.

5. Who was the assignee of US Patent 6,355,245? The assignee of US Patent 6,355,245 was Cell Genesys, Inc.

Citations

[1] Cell Genesys, Inc. (2002). United States Patent 6,355,245. U.S. Patent and Trademark Office. [2] U.S. Patent and Trademark Office. (n.d.). Patent Center. Retrieved from https://patentcenter.uspto.gov/ [3] National Institutes of Health. (n.d.). ClinicalTrials.gov. Retrieved from https://clinicaltrials.gov/

Details for Patent 6,355,245

Applicant	Tradename	Biologic Ingredient	Dosage Form	BLA	Approval Date	Patent No.	Expiredate
Alexion Pharmaceuticals, Inc.	SOLIRIS	eculizumab	Injection	125166	March 16, 2007	6,355,245	2015-06-07

International Patent Family for US Patent 6,355,245

Country	Patent Number	Estimated Expiration
World Intellectual Property Organization (WIPO)	9529697
United States of America	6074642
Portugal	758904
Netherlands	300433
Mexico	9605330