A Treatment Revolution in HER2-Positive Lung Cancer: The Rise of Selective TKIs and ADCs
In this article
We are proud that the comprehensive review my team and I wrote appears in the March 2026 issue of Frontiers in Oncology, one of oncology's respected journals. HER2 alterations, long considered among the most difficult and resistant targets in lung cancer, have now reached a point where they can be controlled with our "precision" approach to medicine.
In this work, we redefine HER2 mutations, which are rare but follow an aggressive course, in light of our philosophy of biological restoration and the latest literature.
HER2 Activation Mechanisms: Three Different Faces
In lung cancer, HER2 fuels tumors through three main mechanisms. Each carries biological clues that directly determine the treatment's "precision":
Frequency: Found in approximately 2% to 4% of patients with NSCLC.
Details: This is the most common "driver" HER2 alteration in NSCLC and the one that responds best to treatment. In particular, the Exon 20 insertion (YVMA) variant accounts for 70-80% of all HER2 mutations (in some studies, "more than half," as stated in the text). It is usually seen in young women who do not smoke and in the adenocarcinoma subtype.
Frequency:
As a Primary Driver: Present at diagnosis in approximately 2% to 4% of patients with NSCLC.
As a Mechanism of EGFR Resistance: When resistance develops in patients receiving EGFR-targeted drugs (TKIs), this proportion may reach 10% to 12%.
Details: An increase in the number of copies of the gene. It is a less common primary driver than mutations but is an important pathway of resistance to EGFR drugs.
In addition, Protein Overexpression is the accumulation of HER2 on the cell surface. Unlike the success seen in breast cancer, "overexpression" alone has been a weak predictor of treatment success in lung cancer; the key determinant is the presence of a mutation.
- Frequency: A very wide range of 2% to 38% has been reported, depending on the criteria and methods (IHC) used in the studies.
- Frequency of the Significant Score (IHC 3+): High-level overexpression (an IHC 3+ score), which is more closely associated with treatment response, is seen in only approximately 2% to 6% of patients.
- Details: The accumulation of HER2 on the cell surface. Unlike the success seen in breast cancer, "overexpression" alone (especially low scores such as IHC 2+) has been a weak predictor of treatment success in lung cancer; the key determinant is the presence of a mutation.
Diagnostic Standards: Why Is NGS Indispensable?
Traditional methods may be inadequate for detecting HER2 mutations. Our study emphasizes that Next-Generation Sequencing (NGS) technology is the "gold standard" in the diagnostic process:
- NGS: Detects Exon 20 insertions (YVMA and non-YVMA), point mutations, and copy-number alterations simultaneously and with high sensitivity.
- FISH: Remains the reference method for confirming gene amplification.
- IHC: Measures protein levels, but the concept of "HER2-Low" has not yet been clinically validated in lung cancer.
A Major Leap in the Treatment Paradigm: ADCs and Next-Generation TKIs
Previously used drugs such as afatinib or poziotinib burdened patients with severe skin and intestinal side effects, both because of their low efficacy and because they also inhibited "wild-type EGFR." Today, two revolutionary classes stand out:
1. Antibody-Drug Conjugates (ADCs): Biological Missiles
Trastuzumab Deruxtecan (T-DXd): Approved in 2022, this agent can clear cells carrying HER2 mutations with near-surgical precision through its "bystander effect" (also killing neighboring cells). In the DESTINY-Lung studies, it achieved response rates of around 50% and notable survival results.
2. Next-Generation Selective TKIs (More Powerful, Fewer Side Effects)
Two new molecules that have made their mark on 2025 and 2026 have made treatment much more comfortable with pills taken by mouth:
| Drug | Feature | Response Rate (ORR) | Clinical Advantage |
|---|---|---|---|
| Zongertinib | Exon 20-selective, irreversible TKI | %77 | Spares wild-type EGFR; rash and diarrhea are minimal. |
| Sevabertinib | Reversible dual HER2/EGFR TKI | %64 - %71 | Effective even in resistant cases after ADC treatment. |
Overcoming the "Barriers" in Brain Metastases
Brain metastases develop over time in 30-50% of patients with HER2-mutated lung cancer. While this was once seen as a "final stop," new agents cross the blood-brain barrier with considerable success:
- Zongertinib: Achieved an intracranial response rate of 41% in patients with brain metastases.
- T-DXd (ADC): Can shrink brain tumors with an intracranial objective response of up to 50%.
These data demonstrate that we have "precision" systemic options that may defer radiotherapy in the management of brain metastases.
Current Treatment Algorithm (2026)
With the ongoing DESTINY-Lung04 and Beamion LUNG-2 studies, these targeted drugs are expected to move into 1. line treatment (as the initial option) very soon.
DROZDOGAN Academy Commentary
For years, we watched HER2 mutations in lung cancer as a "silent threat." Yet, in keeping with our philosophy of biological restoration, the real issue is to hear the genetic cry within that silence correctly and provide a "precise" response. This review does more than list new drugs; it also explains how we can close that small Exon 20 turning in the cancer cell's DNA.
Next-generation selective TKIs and smart ADCs now promise our patients a longer, higher-quality life without the devastating side effects of chemotherapy. The oncology of the future is being built on this precise guidance, which protects the patient as a whole, crosses barriers (the brain), and grasps the depth of biology. Healing rises in the compassionate, sharp light of science.
Scientific References
- 1. Balli S, Basoglu T, Ozdogan M. "Evolving treatment strategies for HER2-altered non-small-cell lung cancer: the rise of TKIs and ADCs." Frontiers in Oncology. 2026;16:1771869. doi:10.3389/fonc.2026.1771869
- 2. Heymach JV, et al. "Zongertinib in previously treated HER2-mutant non-small-cell lung cancer." N Engl J Med. 2025.
- 3. Li BT, et al. "Trastuzumab deruxtecan in HER2 mutant non-small-cell lung cancer." N Engl J Med. 2022.
Was this article helpful?
Your feedback helps us improve our content.
Reader comments
Share your comment
Your name and comment are published only after administrator approval. Your email address is never shown to visitors.
Be the first to comment.