Kaigene Licenses Autoimmune Drug Candidate KG006 to Taisho Pharmaceutical for Japan

Partnership Aims to Expand Autoimmune Treatment Development in Japan

Kaigene, Inc., a biotechnology company based in the United States, has signed an exclusive licensing agreement with Taisho Pharmaceutical Co., Ltd. to develop and commercialize its autoimmune drug candidate, KG006, in Japan.

The agreement gives Taisho exclusive rights to handle the clinical development, regulatory approval, and commercialization of KG006 in the Japanese market. The move is expected to strengthen both companies' position in the growing autoimmune disease treatment space.

Kaigene to Receive Upfront and Milestone Payments

As part of the agreement, Kaigene will receive an upfront payment of $5 million.

The company can also earn additional payments based on the progress of the drug, including:

• Up to $22 million in development, regulatory, and commercial milestone payments
• Up to ¥57.5 billion (approximately $351 million) linked to development, regulatory approvals, and sales milestones
• Tiered royalties on future product sales in Japan

These payments will depend on the successful achievement of specific clinical, regulatory, and commercial targets.

Taisho Will Lead Development in Japan

Under the licensing agreement, Taisho Pharmaceutical will take full responsibility for moving KG006 through clinical trials, obtaining regulatory approval, and bringing the treatment to patients in Japan.

The company already has strong experience in autoimmune diseases, making it a strategic partner for Kaigene.

Why Taisho Was Chosen

Taisho Pharmaceutical has built a strong reputation in autoimmune disease treatment.

One of its biggest successes has been Nanozora, an anti-TNF VHH antibody therapy that has been successfully developed and commercialized in Japan.

Because of this experience, Kaigene believes Taisho has the expertise, clinical capabilities, and commercial infrastructure needed to introduce KG006 successfully into the Japanese market.

Partnership Complements Existing Celltrion Agreement

This new agreement does not replace Kaigene's existing partnership with Celltrion Inc.

Celltrion already holds the global development and commercialization rights for KG006 outside Greater China and Japan.

With Taisho now handling Japan, Kaigene has completed another important part of its global commercialization strategy.

Companies May Collaborate on Global Phase III Trial

The agreement also opens the door for Taisho to participate in the planned multi-regional Phase III clinical trial for KG006.

The study is expected to be led by Celltrion.

If everything moves forward as planned, Celltrion, Kaigene, and Taisho will work together to speed up global clinical development and potentially shorten the overall timeline for bringing KG006 to patients.

CEO Says Partnership Strengthens Global Strategy

Kaigene founder and Chief Executive Officer Minjae Shin said the partnership is another major step in the company's global development plan.

According to Shin, today's drug development environment requires companies to combine their strengths instead of working independently.

He explained that Taisho's expertise in Japan, together with Celltrion's global development capabilities and Kaigene's antibody technology, creates a strong partnership that can accelerate clinical trials and future commercialization.

He also noted that the three companies together form what he described as "One Team" for the global development of KG006.

What Is KG006?

KG006, also known as CT-P77 by Celltrion, is a next-generation human neonatal Fc receptor (hFcRn) inhibitor.

The drug is being developed for autoimmune diseases caused by harmful antibodies attacking the body's own tissues.

Researchers believe KG006 could become a best-in-class therapy because it is designed to offer:

• Deep reduction of disease-causing antibodies
• Longer-lasting treatment effects
• A convenient subcutaneous injection that patients may be able to administer themselves

FcRn inhibitors are becoming an important class of medicines because they have the potential to treat several autoimmune diseases with a single treatment approach.

Kaigene Continues to Expand Its Autoimmune Pipeline

Kaigene focuses on developing antibody-based treatments for autoimmune diseases.

Its research is built around the company's proprietary PDEG platform, which is designed to remove harmful antibodies while also reducing the activity of B cells that produce them.

The company has continued to expand through strategic partnerships.

In April 2025, Kaigene entered a collaboration with a U.S.-based venture capital group to develop additional autoimmune therapy programs.

Later, in November 2025, it signed a global licensing agreement with Celltrion, giving Celltrion worldwide rights for KG002 and global rights outside Japan and Greater China for KG006.

Company Is Also Developing Brain-Targeted Antibody Technology

Alongside its autoimmune programs, Kaigene is developing another technology platform called NanoBx.

This platform is designed to improve the delivery of antibody medicines across the blood-brain barrier.

The goal is to develop new treatments for central nervous system autoimmune diseases, an area where few therapies currently exist.

Taisho Continues to Expand Its Biopharmaceutical Portfolio

Taisho Pharmaceutical is headquartered in Tokyo and is well known for both prescription medicines and over-the-counter healthcare products.

The company has steadily expanded its biopharmaceutical business through research, licensing agreements, and investments in innovative therapies.

Its expertise in autoimmune diseases makes KG006 another important addition to its growing pipeline of advanced antibody-based medicines.

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