U.S. Food and Drug Administration Accepts New Drug Application for Zipalertinib for the Treatment of Locally Advanced or Metastatic Non-Small Cell Lung Cancer with EGFR Exon 20 Insertion Mutations

• NDA submission based on the Phase 2b REZILIENT1 clinical trial, which demonstrated clinically meaningful and durable responses in patients with relapsed EGFR exon 20 insertion–mutated NSCLC
• Prescription Drug User Fee Act (PDUFA) target action date is February 27, 2027

Taiho Oncology, Inc., Taiho Pharmaceutical Co., Ltd., and Cullinan Therapeutics, Inc. (NASDAQ:CGEM) today announced that the U.S. Food and Drug Administration (FDA) has accepted a New Drug Application (NDA) for zipalertinib for the treatment of patients with locally advanced or metastatic non-small cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR) exon 20 insertion (ex20ins) mutations whose disease has progressed on or after platinum-based chemotherapy, with or without amivantamab. The Prescription Drug User Fee Act (PDUFA) target action date is February 27, 2027.

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The NDA is supported by data from the Phase 2b part of the REZILIENT1 clinical trial of zipalertinib monotherapy in patients with NSCLC harboring EGFR ex20ins mutations who have received prior therapy. The study met its primary endpoint of objective response rate. Study results from REZILIENT1 were presented at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting and simultaneously published in the Journal of Clinical Oncology.

"Zipalertinib was discovered at Taiho Pharmaceutical Co., Ltd., and has been developed with a focus on addressing the unmet needs of patients with EGFR exon 20 insertion-mutated non-small cell lung cancer," said Harold Keer, MD, PhD, Chief Medical Officer, Taiho Oncology. "The FDA's acceptance of the NDA for zipalertinib is an important milestone for this program, and we look forward to working with FDA during the review process."

"Zipalertinib is a compound created using Taiho Pharmaceutical's proprietary drug discovery and development technologies, Cysteinomix, with the aim of delivering a new treatment option to address high unmet medical needs," said Takeshi Sagara, PhD, Executive Director, Board Member, Medical Affairs, Translational Development, Clinical Development, Discovery and Preclinical Research at Taiho Pharmaceutical. "The FDA's acceptance of the NDA represents an important milestone, reflecting the scientific and clinical data accumulated to date. We will continue to work closely with Taiho Oncology, Cullinan Therapeutics and the FDA throughout the review process, with the shared goal of ultimately delivering a new treatment option to patients with non-small cell lung cancer EGFR exon 20 insertion mutations."

"FDA acceptance of the zipalertinib NDA is an important step toward making zipalertinib available for people living with non-small cell lung cancer with EGFR exon 20 insertion mutations, who continue to face limited treatment options," said Jeffrey Jones, MD, MBA, Chief Medical Officer, Cullinan Therapeutics. "We are deeply grateful to the patients and families who have participated in the REZILIENT program, and to the investigators, study teams, and advocates whose collaboration made achievement of this milestone possible. We believe zipalertinib has the potential to help address a significant unmet need, and we look forward to working with our partners at Taiho with the goal of bringing zipalertinib to patients waiting for new treatment options."

Summary of Primary Study Results:

• Zipalertinib demonstrated clinically meaningful efficacy in the primary efficacy population (n=176), including 51 patients who had received prior amivantamab.
• The confirmed objective response rate (ORR) was 35%. Median duration of response (mDOR) was 8.8 months.
• In patients treated after prior platinum-based chemotherapy only (n=125), ORR was 40% with a mDOR of 8.8 months.
• In exploratory subgroup analyses:
  • Patients who had received prior amivantamab without other ex20ins-targeted therapy (n=30) showed a confirmed ORR of 30% and mDOR of 14.7 months.
    
    
    
    Patients with brain metastases (n=68) showed a confirmed ORR of 31% and a mDOR of 8.3 months.
• The safety profile of zipalertinib was manageable and consistent with previously reported data.¹ The most common treatment-emergent adverse events were paronychia, rash, anemia, dermatitis acneiform, diarrhea, dry skin, nausea and stomatitis. Most treatment-emergent adverse events were grade 1 or 2 per NCI-Common Terminology Criteria for Adverse Events (CTCAE v5.0).

Zipalertinib is an oral EGFR tyrosine kinase inhibitor. Zipalertinib received Breakthrough Therapy Designation in 2021 for the treatment of patients with locally advanced or metastatic NSCLC harboring EGFR ex20ins mutations who have previously received platinum‑based systemic chemotherapy.

About REZILIENT1

REZILIENT1 (Researching Zipalertinib in EGFR Non-Small Cell Lung Cancer Tumors) is a Phase 1/2 clinical trial (NCT04036682) to evaluate efficacy and safety of zipalertinib in adult patients with locally advanced or metastatic NSCLC harboring EGFR ex20ins mutations who have received prior therapy. Patients were treated with oral zipalertinib 100 mg twice daily. The primary endpoints were objective response rate (ORR) and duration of response (DOR) as assessed by blinded independent central review (ICR) per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1. Adverse events were characterized and graded according to the NCI-Common Terminology Criteria for Adverse Events (CTCAE v5.0).

About Zipalertinib

Zipalertinib (development code: CLN-081/TAS6417) is an orally available small molecule designed to target activating mutations in EGFR. The molecule was selected because of its ability to inhibit EGFR variants with ex20ins mutations, while sparing wild-type EGFR. Zipalertinib is designed as a next generation, irreversible EGFR inhibitor for the treatment of a genetically defined subset of patients with non-small cell lung cancer. Zipalertinib has received Breakthrough Therapy Designation from the FDA for the treatment of patients with locally advanced or metastatic NSCLC harboring epidermal growth factor EGFR ex20ins mutations who have previously received platinum-based systemic chemotherapy. Zipalertinib is investigational and has not been approved by any health authority.

Zipalertinib is being developed by Taiho Oncology, Inc., and its parent company, Taiho Pharmaceutical Co., Ltd. worldwide, and in collaboration with Cullinan Therapeutics, Inc. in the U.S.

About EGFR Exon 20 Insertion Mutations

NSCLC is a common form of lung cancer and up to 4% of all cases globally have EGFR ex20ins, which makes them the third most common EGFR mutation subtype.² In the United States, approximately 16% of patients with NSCLC harbor EGFR mutations,² with insertions at exon 20 accounting for up to 12% of these mutations.³

About Taiho Oncology, Inc.

The mission of Taiho Oncology, Inc. is to improve the lives of patients with cancer, their families and their caregivers. The company specializes in the development and commercialization of orally administered anti-cancer agents for various tumor types. Taiho Oncology has a robust pipeline of small-molecule clinical candidates targeting solid-tumor and hematological malignancies, with additional candidates in pre-clinical development. Taiho Oncology is a subsidiary of Taiho Pharmaceutical Co., Ltd. which is part of Otsuka Holdings Co., Ltd. Taiho Oncology is headquartered in Princeton, New Jersey and oversees its parent company's European and Canadian operations, which are located in Baar, Switzerland and Oakville, Ontario, Canada.

For more information, visit https://www.taihooncology.com/, and follow us on LinkedIn and X.

Taiho Oncology and the Taiho Oncology logo are registered trademarks of Taiho Pharmaceutical Co., Ltd.

About Taiho Pharmaceutical Co., Ltd. (Japan)

Taiho Pharmaceutical, a subsidiary of Otsuka Holdings Co., Ltd. (https://www.otsuka.com/en/), is an R&D-driven specialty pharma focusing on the fields of oncology and immune-related diseases. Its corporate philosophy takes the form of a pledge: "We strive to improve human health and contribute to a society enriched by smiles." In the field of oncology, in particular, Taiho Pharmaceutical is known as a leading company in Japan for developing innovative medicines for the treatment of cancer, a reputation that is rapidly expanding through their extensive global R&D efforts. In areas other than oncology, as well, the company creates and markets quality products that effectively treat medical conditions and can help improve people's quality of life. Always putting customers first, Taiho Pharmaceutical also aims to offer consumer healthcare products that support people's efforts to lead fulfilling and rewarding lives. For more information about Taiho Pharmaceutical, please visit https://www.taiho.co.jp/en.

About Cullinan Therapeutics

Cullinan Therapeutics, Inc. (NASDAQ:CGEM) is a biopharmaceutical company developing potential first- or best-in-class, high-impact therapies for autoimmune diseases and cancer. Cullinan pursues promising therapeutic targets while leveraging core expertise in T cell engagers, which are established in oncology and are now advancing into autoimmune diseases. With a clinical-stage pipeline built on a rigorous scientific approach and purposeful innovation, Cullinan is advancing its mission to deliver new standards of care for patients. Learn more about Cullinan at https://cullinantherapeutics.com/, and follow Cullinan on LinkedIn and X.

Forward Looking Statements

This press release contains forward-looking statements within the meaning of The Private Securities Litigation Reform Act of 1995. These forward-looking statements include, but are not limited to, express or implied statements regarding the company's beliefs and expectations regarding the potential for zipalertinib to obtain FDA approval for the treatment of patients with locally advanced or metastatic NSCLC harboring EGFR ex20ins mutations whose disease has progressed on or after platinum-based chemotherapy, with or without amivantamab, the anticipated timing of such FDA approval, the safety and efficacy profile of zipalertinib and its potential to address unmet medical need, and other statements that are not historical facts. The words "believe," "continue," "could," "estimate," "expect," "intends," "may," "plan," "potential," "project," "pursue," "will," and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words.

Any forward-looking statements in this press release are based on management's current expectations and beliefs of future events and are subject to known and unknown risks and uncertainties that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. These risks include, but are not limited to, the following: uncertainty regarding the timing and results of regulatory submissions; the risk that any NDAs, INDs or other regulatory submissions we may file with the United States Food and Drug Administration or other global regulatory agencies are not accepted or cleared on our expected timelines, or at all; the success of our clinical trials and preclinical studies; the risks related to our ability to protect and maintain our intellectual property position; the risks related to manufacturing, supply, and distribution of our product candidates; the risk that any one or more of our product candidates, including those that are co-developed, will not be successfully developed and commercialized; the risk that the results of preclinical studies or clinical studies will not be predictive of future results in connection with future studies; the effect of changes in global economic conditions, including uncertainties related to international trade policies, tariffs and supply chain dynamics on our business and operations; and the success of any collaboration, partnership, license or similar agreements. These and other important risks and uncertainties discussed in our filings with the Securities and Exchange Commission, including under the caption "Risk Factors" in our most recent Annual Report on Form 10-K and subsequent filings with the SEC, could cause actual results to differ materially from those indicated by the forward-looking statements made in this press release. While we may elect to update such forward-looking statements at some point in the future, we disclaim any obligation to do so, even if subsequent events cause our views to change, except to the extent required by law. These forward-looking statements should not be relied upon as representing our views as of any date subsequent to the date of this press release. Moreover, except as required by law, neither the company nor any other person assumes responsibility for the accuracy and completeness of the forward-looking statements included in this press release. Any forward-looking statement included in this press release speaks only as of the date on which it was made.

References

1. Piotrowska Z, Tan DS, Smit EF, et al. Safety, tolerability, and antitumor activity of zipalertinib among patients with non-small-cell lung cancer harboring epidermal growth factor receptor exon 20 insertions. Journal of Clinical Oncology. Available at: https://ascopubs.org/doi/full/10.1200/JCO.23.00152.
2. Burnett H, Emich H, Carroll C, et al. Epidemiological and clinical burden of EGFR exon 20 insertion in advanced non-small cell lung cancer: a systematic literature review. PLOS ONE. 2021;16(3):e0247620. Available at: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0247620.
3. Riess JW, Gandara DR, Frampton GM, et al. Diverse EGFR Exon 20 Insertions and Co-Occurring Molecular Alterations Identified by Comprehensive Genomic Profiling of NSCLC. Journal of Thoracic Oncology. 2018 Jul 5;13(10):1560–1568. Available at: https://www.jto.org/article/S1556-0864(18)30770-6/pdf.

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Taiho Oncology

Leigh Labrie

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llabrie@taihooncology.com



Taiho Pharmaceutical Co., Ltd.

Junko Onishi

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junn-onishi@taiho.co.jp



Cullinan Therapeutics

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