On June 1, 2025 Taiho Oncology, Inc., and Cullinan Therapeutics, Inc., reported the publication of positive results from the REZILIENT1 trial in the peer-reviewed Journal of Clinical Oncology (JCO). REZILIENT1 is a Phase 1/2, global, multicenter study of zipalertinib (development code: CLN-081/TAS6417) in patients with non-small cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) exon 20 insertion mutations (ex20ins) who have received prior therapy (Press release, Taiho, JUN 1, 2025, View Source [SID1234653566]). Results from the REZILIENT1 trial will be presented in a simultaneous oral presentation at the 2025 American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Annual Meeting (Abstract #8503).

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The full publication, titled Zipalertinib in Patients With Epidermal Growth Factor Receptor Exon 20 Insertion-Positive Non-Small Cell Lung Cancer Previously Treated With Platinum-Based Chemotherapy With or Without Amivantamab, can be found here.

Highlights of the REZILIENT1 Phase 1/2 trial in the authors’ conclusions include:

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 35.2% overall, and median duration of response (mDOR) and progression-free survival were 8.8 months and 9.4 months, respectively.
In patients treated after prior platinum-based chemotherapy only (n=125), ORR was 40% with mDOR of 8.8 months.
The safety profile of zipalertinib was manageable and consistent with previously reported data.¹
In exploratory subgroup analyses:
Patients who had received prior amivantamab without other ex20ins-targeted therapy showed a confirmed ORR of 30% and mDOR of 14.7 months.
Patients with brain metastases showed a confirmed ORR of 30.9% and a mDOR of 8.3 months.
"Despite recent treatment advances for patients with EGFR ex20ins-mutant NSCLC, there is a lack of oral targeted therapies for patients whose tumors harbor these mutations," said principal investigator Zofia Piotrowska, MD, Assistant Professor, Medicine, Harvard Medical School and a clinical researcher and lung cancer medical oncologist at the Massachusetts General Hospital Cancer Center. "Findings from the Phase 1/2 REZILIENT1 trial support our understanding of zipalertinib as a potential targeted therapy option for patients living with previously treated recurrent or metastatic NSCLC harboring EGFR ex20ins mutations."

Taiho Oncology is actively recruiting patients in the Phase 3 REZILIENT3 trial (NCT05973773).

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