Company Announcements

• Updated efficacy and safety data to be presented from the REZILIENT1 trial of zipalertinib from the cohort of patients with non-small cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) exon 20 insertion mutations (ex20ins) who were previously treated with amivantamab
• Preliminary clinical efficacy and safety data to be presented from the cohort of patients with uncommon non-ex20ins EGFR mutations in the REZILIENT2 trial of zipalertinib

PRINCETON, N.J. and CAMBRIDGE, Mass., Sept. 9, 2025 /PRNewswire/ -- Taiho Oncology, Inc., and Cullinan Therapeutics, Inc., today announced new data from the REZILIENT1 and REZILIENT2 trials of zipalertinib, an oral EGFR tyrosine kinase inhibitor, in patients with advanced or metastatic non-small cell lung cancer (NSCLC). These data will be presented at the IASLC 2025 World Conference on Lung Cancer hosted by the International Association for the Study of Lung Cancer as mini oral presentations on September 9 during the "MA08 - Common and Uncommon EGFR Mutations, New Treatments in the Horizon" session, from 11:30 a.m. – 12:45 p.m. CEST.

A mini oral presentation will highlight updated data from the pivotal Phase 2b REZILIENT1 trial of zipalertinib, focused on patients with NSCLC harboring EGFR ex20ins mutations, who have been previously treated with amivantamab.¹

A second mini oral presentation will highlight Phase 2b preliminary efficacy and safety results from the ongoing, uncommon non-ex20ins EGFR mutations cohort of the REZILIENT2 trial of zipalertinib in patients with advanced or metastatic NSCLC harboring ex20ins and uncommon non-ex20ins EGFR mutations.²

"We're pleased to share longer-term follow-up data from the REZILIENT1 study of zipalertinib for patients with NSCLC harboring EGFR ex20ins mutations who have been previously treated with amivantamab," said Zofia Piotrowska, MD, Associate Professor of Medicine, Harvard Medical School and lung cancer clinical oncologist at the Mass General Cancer Center. "Despite recent treatment advancements, a significant medical need exists for this patient population, underscoring the importance of these data."

"Uncommon non-exon 20 insertion EGFR mutations represent a significant clinical challenge, as they exhibit variable and often suboptimal responses to currently approved tyrosine kinase inhibitors," said Hibiki Udagawa, MD, PhD, thoracic medical oncologist, National Cancer Hospital East, Japan.  "We are pleased to present the interim data from the uncommon non-ex20ins EGFR mutations cohort from the REZILIENT2 trial, potentially demonstrating the need for novel, targeted therapeutic approaches for this patient population."

Authors reported results from the REZILIENT1 study of zipalertinib from the cohort of NSCLC patients with EGFR ex20ins mutations who received prior amivantamab therapy¹

Summary of Efficacy - by Blinded Independent Central Review (BICR):
As of the June 2025 data cutoff, 84 post-amivantamab patients were enrolled in REZILIENT1 and received at least one dose of 100 mg zipalertinib. Patients had received a median of 3 prior lines of therapy, and 54.8% of patients had a history of brain metastases.

With follow-up of more than 9 months, zipalertinib demonstrated:

• In all patients (n=84), confirmed objective response rate (ORR) was 27.4% with median duration of response (mDOR) of 8.5 months, and the disease control rate (DCR) was 84.5%.
  
  
• In patients with prior amivantamab only (n=54), ORR was 31.5% with mDOR of 9.5 months, and the DCR was 87.0%.
  
  
• In patients with prior amivantamab and other ex20ins-targeted therapy (n=30), ORR was 20.0% with mDOR of 8.3 months, and the DCR was 80.0%.
  
  
• In patients with brain metastases who received prior amivantamab only (n=31), the systemic ORR was 29%.

Summary of Safety and Tolerability 
The safety analysis population included all post-amivantamab patients in REZILIENT1 who received at least one dose of 100 mg zipalertinib (n=84). The results showed that zipalertinib 100 mg twice daily demonstrated a manageable safety profile in patients who progressed on prior chemotherapy and amivantamab with no new safety signals.

The most common treatment-emergent adverse events (TEAEs, all-grade) were paronychia (41.7%), anemia (38.1%), rash (34.5%), nausea (28.6%), diarrhea (22.6%), dry skin (21.4%), dermatitis acneiform (21.4%) and dyspnea (20.2%).

The most common grade ≥3 TEAEs were anemia (15.5%), pneumonia (10.7%), dyspnea (6.0%), rash (3.6%), diarrhea (2.4%) and stomatitis (2.4%).

Authors reported results from the REZILIENT2 study of zipalertinib from the cohort of patients with NSCLC harboring uncommon non-exon 20 insertion EGFR mutations² 

Summary of Preliminary Efficacy –by Investigator
As of the March 2025 data cutoff, 40 patients were enrolled in the REZILIENT2 Cohort D and received zipalertinib 100 mg orally twice daily. Previously treated patients had received a median of 2 prior lines of therapy, and 30% of all patients enrolled, including treatment-naïve, had a history of brain metastases.

As of the data cut-off, zipalertinib demonstrated:

• In the overall efficacy population (n=40), confirmed ORR was 30% with a mDOR of 7.75 months, and the disease control rate (DCR) was 70%.
• In the treatment-naïve population (n=8), ORR was significantly higher (62.5%) compared to the previously treated patient population (n=32, ORR 21.9%).

Summary of Preliminary Safety and Tolerability 
The safety analysis population included all REZILIENT2 patients in Cohort D who received at least one dose of 100 mg zipalertinib (n=40). The results showed that zipalertinib 100 mg twice daily demonstrated a manageable safety and tolerability profile with no new safety signals.

The most common treatment-related adverse events (TRAEs, all-grade) were paronychia (47.5%), dermatitis acneiform (37.5%), stomatitis (32.5%), anemia (30.0%), diarrhea (22.5%), rash (20.0%), and dry skin (15.0%). The majority of TRAEs were grade 1 or 2.

The most common grade ≥3 TRAEs were paronychia (5.0%), pneumonitis and anemia (5.0%).

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 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 ORR and DOR as assessed by blinded independent central review (ICR) per RECIST v1.1. Adverse events were characterized and graded according to Common Terminology Criteria for Adverse Events (CTCAE v5.0).

About REZILIENT2
REZILIENT2 is a Phase 2b clinical trial (NCT05967689), evaluating zipalertinib in patients with locally advanced/metastatic NSCLC harboring ex20ins and uncommon single or compound EGFR mutations. Patients were treated with oral zipalertinib 100 mg twice daily. The primary endpoint was ORR and confirmed per investigator-assessed Response Evaluation Criteria in Solid Tumours (RECIST) v1.1 and the secondary endpoints included DOR, DCR and safety.

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. Zipalertinib is investigational and has not been approved by any health authority.

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

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 Cullinan Therapeutics
Cullinan Therapeutics, Inc.  (Nasdaq: CGEM) is a biopharmaceutical company dedicated to creating new standards of care for patients. Cullinan has strategically built a diversified portfolio of clinical-stage assets that inhibit key drivers of disease or harness the immune system to eliminate diseased cells in both autoimmune diseases and cancer. Cullinan's portfolio encompasses a wide range of modalities, each with the potential to be best and/or first in class. Anchored in a deep understanding of oncology, immunology, and translational medicine, we create differentiated ideas, identify the most appropriate targets, and select the optimal modality to develop transformative therapeutics across a wide variety of autoimmune and cancer indications. We push conventional boundaries from candidate selection to differentiated therapeutic, applying rigorous go/no go criteria at each stage of development to fast-track only the most promising molecules to the clinic and, ultimately, commercialization. With deep scientific expertise, our teams exercise creativity and urgency to deliver on our promise to bring new therapeutic solutions to patients. Learn more about Cullinan at https://cullinantherapeutics.com/, and follow us 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 our plans regarding future data presentations, the clinical development and regulatory filing plan and timeline of zipalertinib, 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 NDA or other regulatory submissions we may file with the United States Food and Drug Administration or other global regulatory agencies are not 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; 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.

Contacts

Taiho Oncology

Leigh Labrie
(609) 664-9878
llabrie@taihooncology.com

Cullinan Therapeutics

Investors 
Nick Smith
+1 401.241.3516
nsmith@cullinantx.com

Media 
Rose Weldon   
+1 215.801.7644   
rweldon@cullinantx.com

References:

1. Z. Piotrowska et al. Zipalertinib in NSCLC patients (pts) with EGFR exon 20 insertion (ex20ins) mutations who received prior amivantamab

2. Hibiki Udagawa et al. Phase 2 Interim Results of Zipalertinib in Patients With NSCLC Harboring Uncommon Non-Exon 20 Insertion EGFR Mutations

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SOURCE Taiho Oncology