SUMMARY: The FDA on February 26, 2026, granted accelerated approval to Zongertinib (HERNEXEOS®), a kinase inhibitor, for an expanded indication for adults with unresectable or metastatic non-squamous Non-Small Cell Lung Cancer (NSCLC) whose tumors have HER2 (ERBB2) Tyrosine Kinase Domain (TKD) activating mutations, as detected by an FDA-authorized test.
The American Cancer Society estimates that for 2026, about 229,410 new cases of lung cancer will be diagnosed and 124,990 patients will die of the disease. Lung cancer is the leading cause of cancer-related mortality in the United States. Non-Small Cell Lung Cancer (NSCLC) accounts for approximately 85% of all lung cancers and Adenocarcinoma is now the most frequent histologic subtype of lung cancer.
The HER or erbB family of receptors consist of HER1, HER2, HER3 and HER4. HER2 is a Tyrosine Kinase Receptor expressed on the surface of several tumor types including Breast, Gastric, Lung and Colorectal cancers. It is a growth-promoting protein, and HER2 overexpression/HER2 gene amplification is often associated with aggressive disease and poor prognosis in certain tumor types.
HER2 mutations unlike HER2 overexpression and gene amplification are oncogenic drivers and are detected in 2 to 4% of NSCLCs. They are more often detected in younger, female and never-smokers, and almost exclusively in Adenocarcinomas. Next-generation sequencing is used to identify HER2 mutations. Majority of HER2 mutations (80-90%) occur in exon 20, as either a duplication or an insertion of 12 nucleotides, resulting in the addition of four amino acids (YVMA) at codon 775 in the kinase domain. This distinct molecular entity is characterized by specific pathological and clinical behavior. These acquired HER2 gene mutations have been independently associated with cancer cell growth, aggressive form of disease and poor prognosis, and with an increased incidence of brain metastases.
The FDA in 2022 granted accelerated approval to ENHERTU® (Trastuzumab deruxtecan), for adult patients with unresectable or metastatic NSCLC whose tumors have HER2 (ERBB2) mutations. This is the first drug approved for HER2-mutant NSCLC. Trastuzumab deruxtecan, however, can be associated with toxicities including Interstitial Lung Disease (ILD). Similarly, Pan-HER TKIs such as Poziotinib and Pyrotinib have shown limited efficacy and are frequently associated with EGFR-related adverse events, underscoring the urgent need for more targeted, better-tolerated therapies.
Zongertinib (HERNEXEOS®) is a novel, oral, irreversible Tyrosine Kinase Inhibitor designed to selectively target HER2 while sparing EGFR, thus minimizing common toxicities such as rash and diarrhea.
Beamion LUNG-1 is an ongoing Phase 1a/1b multicenter, multi-cohort trial, evaluating Zongertinib in patients with HER2-altered advanced or metastatic solid tumors (Phase 1a) and those with HER2-mutant advanced or metastatic NSCLC across multiple clinically relevant patient cohorts (Phase 1b). In the Phase 1a dose-escalation trial, Zongertinib showed encouraging preliminary activity at the recommended expansion doses of 120 mg and 240 mg once daily, with a low incidence of Grade 3 or higher adverse events.
The Phase 1b portion is an ongoing study of Zongertinib in three key Cohorts (Cohort 1, 2 and 5) and three exploratory Cohorts (Cohorts 3, 4 and 6)
- Cohort 1: Pretreated NSCLC patients with tumors harboring HER2 mutations in the TKD (Tyrosine Kinase Domain), the most common category of HER2 mutations encountered in the clinic.
- Cohort 2: Treatment-naïve NSCLC with HER2 TKD mutation
- Cohort 3: NSCLC patients whose tumor had HER2 mutations outside the TKD or HER2 TKD mutation-positive squamous NSCLC, pretreated
- Cohort 4: NSCLC with active brain metastases with a HER2 TKD mutation
- Cohort 5: NSCLC patients whose tumors had HER2 mutations within the TKD and had previously received HER2-directed ADCs, including Trastuzumab deruxtecan.
- Cohort 6: NSCLC patients with HER2 TKD mutation and prior systemic treatment including HER2-directed ADCs.
(Some reports define Cohort 5 as the post-ADC cohort. However, clinical trial documentation indicates Cohort 6 specifically addresses the requirement for previous HER2-directed ADC treatment in specific phases of the study)
Cohorts 3, 4 and 6 are exploratory
Patients were initially treated at 120 mg or 240 mg daily and following interim analysis, 120 mg was selected as the optimal dose based on a favorable efficacy and safety balance.
The FDA in August 2025, granted accelerated approval to Zongertinib, for adults with unresectable or metastatic non-squamous Non-Small Cell Lung Cancer (NSCLC) whose tumors have HER2 (ERBB2) Tyrosine Kinase Domain (TKD) activating mutations and who have received prior systemic therapy. This was based on Objective Response Rate (ORR) and Duration of Response (DOR). This cohort study also suggested that Zongertinib may offer a viable treatment option even in patients who have progressed on ADCs or harbor atypical HER2 alterations.
The present accelerated approval was based on the efficacy of Zongertinib in unresectable or metastatic, non-squamous NSCLC with HER2 TKD mutation, who had not received systemic therapy for advanced disease (Cohort 2). The efficacy analysis included 72 patients (N=72) and the major efficacy outcome measures were Objective Response Rate (ORR) and Duration of Response (DOR) as determined by Blinded Independent Central Review (BICR)
The ORR was 76%, with Complete Response seen in 11% and Partial Response noted in 65% of patients. Sixty four percent (64%) of responders had a DOR of 6 months or more and 44% had a DOR of 12 months or more. The researchers added that the present efficacy reinforces the existing efficacy data for Zongertinib in previously treated NSCLC tumors with HER2 TKD activating mutations.
Safety and Tolerability
In a pooled safety population, which included 292 patients with HER2-mutant NSCLC, both treatment-naïve and previously treated, the most common adverse reactions were diarrhea (54%), rash (27%), hepatotoxicity (26%), fatigue (25%), nausea (23%), and musculoskeletal pain (21%), and upper respiratory tract infection (20%). No cases of drug-related interstitial lung disease were observed. The safety profile compares favorably with existing HER2-targeted agents, including Trastuzumab deruxtecan, which has reported interstitial lung disease rates of up to 26% in earlier trials.
Clinical Context and Future Directions
Compared with other HER2-targeted agents including Trastuzumab deruxtecan and investigational pan-HER TKIs, Zongertinib stands out as the first targeted therapy for treatment naïve patients with HER2-mutant advanced NSCLC, with its high response rates, durability, and manageable toxicity, and once daily oral administration. While cross-study comparisons have inherent limitations, these results support Zongertinib as a promising, HER2-selective oral agent for patients with HER2-mutant NSCLC. The ongoing Phase 3 Beamion LUNG-2 trial (NCT06151574) will further assess Zongertinib in the first-line setting, providing critical data on its role relative to current standard-of-care therapies.
Conclusion
Zongertinib has emerged as a strong candidate in the evolving landscape of HER2-mutant NSCLC. With high response rates, durable outcomes, and a favorable safety profile, it may soon offer oncologists a powerful new tool for treating this difficult-to-manage patient population.
https://www.fda.gov/drugs/resources-information-approved-drugs/fda-grants-accelerated-approval-zongertinib-unresectable-or-metastatic-non-squamous-non-small-cell
