# Enhertu (Trastuzumab Deruxtecan) May Offer the Strongest Benefit for HER2-Mutant Lung Cancer After Initial Treatment Fails

A new systematic review and indirect treatment comparison suggests that trastuzumab deruxtecan (T-DXd, brand name Enhertu) may be the best treatment option for adults with HER2-mutant non-small cell lung cancer whose disease has progressed after one or more prior therapies. Researchers compared T-DXd against nine other guideline-recommended treatments, including chemotherapy, immunotherapy, and drug combinations, and found T-DXd had a 100% probability of being the best treatment for delaying cancer progression. Patients taking T-DXd also had dramatically higher response rates (tumor shrinkage), with odds 6 to 21 times higher than with other regimens.

# Enhertu (Trastuzumab Deruxtecan) May Offer the Strongest Benefit for HER2-Mutant Lung Cancer After Initial Treatment Fails

## Table of Contents

- Key Points
- Understanding Lung Cancer and HER2 Mutations
- Why This Research Matters for Patients
- How the Research Was Conducted
- Which Studies Were Included
- Key Findings: How T-DXd Compared to Other Treatments
- What This Means for Patients
- Study Limitations
- Recommendations for Patients and Families
- Frequently Asked Questions
- Source Information

## Key Points

- For HER2-mutant advanced non-small cell lung cancer, T-DXd shown in systematic review to delay progression more than other guideline-recommended treatments after one prior therapy.
- Across all comparators, the probability T-DXd most effectively delayed progression was 100%, with risk reduction of 67% to 85% versus standard chemotherapies.
- Patients on T-DXd had about 49% tumor response, with odds of response six to 21 times higher than chemotherapy or immunotherapy regimens.
- Overall survival consistently favored T-DXd, though the probability it was most effective for survival was at least 59%, being less definitive.
- This indirect analysis used historical comparator trials, so HER2 mutation was not tested in comparator groups. Only direct trials can provide definitive proof.

## Understanding Lung Cancer and HER2 Mutations

Lung cancer remains the most common type of cancer worldwide and the leading cause of cancer-related death. Each year, there are approximately **2.48 million new cases** and **1.82 million lung cancer-related deaths** globally.

Non-small cell lung cancer (NSCLC) is the largest subtype of lung cancer. It represents **80% to 85% of all cases**. About **70% of NSCLC patients have what doctors call non-squamous histology**, meaning the cancer cells do not have the flat, scale-like appearance typical of squamous cell cancer.

Within NSCLC, a specific genetic change called a **HER2 mutation (also known as ERBB2 mutation)** has emerged as an important target for treatment. HER2 stands for human epidermal growth factor receptor 2. Normally, this gene helps cells grow and divide. When it is mutated, it can drive cancer growth.

HER2 mutations are found in **3% to 5% of NSCLC cases** and in **2% to 4% of lung adenocarcinomas** (a common type of non-squamous lung cancer). Patients with HER2-mutant NSCLC tend to have a poor prognosis when treated with medicines that do not target HER2. They may also have a higher chance of developing cancer spread to the brain (central nervous system metastases) than patients with the normal, or wild-type, HER2 gene.

## Why This Research Matters for Patients

Historically, patients with HER2-mutant NSCLC had limited treatment options. No targeted therapy was available for this specific mutation. Before HER2-targeted medicines existed, HER2 mutations were not routinely tested for in clinical practice. As a result, HER2-mutant patients were largely treated the same way as other NSCLC patients without actionable genetic drivers.

For patients whose disease has progressed after first-line treatment, the standard options have included immunotherapy agents (such as nivolumab, pembrolizumab, or atezolizumab), chemotherapy (such as docetaxel or pemetrexed), and vascular endothelial growth factor (VEGF) inhibitors. But these treatments provide limited benefit for HER2-mutant patients. Clinical studies show they offer a **progression-free survival (PFS) benefit of only about 3 to 5 months** and a **median overall survival (OS) of 10 months or less**. PFS is the length of time during and after treatment that a patient lives without the cancer growing. OS is the length of time a patient lives from diagnosis or the start of treatment.

That situation changed when **T-DXd (trastuzumab deruxtecan, Enhertu)** arrived. T-DXd is an **antibody drug conjugate**, a precision medicine that combines an anti-HER2 antibody with a novel topoisomerase I inhibitor (a type of chemotherapy drug). The two parts are linked by a peptide linker that can be cleaved by enzymes. The antibody part seeks out HER2 on cancer cells, delivering the chemotherapy directly to the tumor.

T-DXd was the first HER2-directed therapy approved for patients with HER2-mutant unresectable locally advanced or metastatic NSCLC (a/mNSCLC) in the second-line setting or later. It is now recommended by three major guidelines: the **European Society for Medical Oncology (ESMO)**, the **National Comprehensive Cancer Network (NCCN)**, and the **American Society of Clinical Oncology (ASCO)**.

The drug was evaluated in two key trials. **DESTINY-Lung01 (NCT03505710)** was a multicenter, open-label phase II trial that tested T-DXd at 6.4 mg/kg every 3 weeks. **DESTINY-Lung02 (NCT04644237)**, a multicenter, double-blind, randomized phase II trial, tested two doses (5.4 mg/kg or 6.4 mg/kg every 3 weeks) in patients with HER2-mutant advanced or metastatic NSCLC whose disease had progressed after one or more previous treatments, including platinum-based chemotherapy. In both studies, T-DXd produced deep and durable responses in heavily pretreated patients, and it delayed disease progression and death. T-DXd also showed activity inside the brain based on pooled data from both trials; the presence of brain metastases at the start did not affect how well the drug worked systemically.

Because the 5.4 mg/kg dose had a more favorable safety profile than 6.4 mg/kg, the **U.S. Food and Drug Administration (FDA)** and the **European Medicines Agency (EMA)** approved T-DXd monotherapy at **5.4 mg/kg** for adults with a/mNSCLC whose tumors have an activating HER2 mutation and who need systemic therapy after platinum-based chemotherapy, with or without immunotherapy. The study used the 23 December 2022 data cut-off from DESTINY-Lung02 as its primary analysis.

Because HER2-mutant cancer is rare, especially in the later-line setting, no clinical trial has ever directly compared T-DXd to other available therapies in this patient population. This systematic review was designed to fill that gap.

## How the Research Was Conducted

### Systematic Literature Review and Patient Selection

The researchers conducted a **systematic literature review (SLR)** to find all clinical trials in adults (18 years or older) with non-squamous advanced or metastatic NSCLC. They followed recognized guidelines from the **National Institute for Health and Care Excellence (NICE)** and the **Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)** framework.

The research focused on non-squamous (NSQ) patients for an important reason: all but one patient in the DESTINY-Lung02 trial had NSQ NSCLC, and HER2 mutations are most common in this subtype.

Trials were eligible if they studied patients being treated in the second line or later and if they tested any of these treatments:

- Platinum-based chemotherapy (cisplatin, carboplatin, or oxaliplatin)
- Nivolumab (Opdivo) as a single drug
- Atezolizumab (Tecentriq) as a single drug
- Pembrolizumab (Keytruda) as a single drug for patients with PD-L1 above 1%
- Docetaxel
- Pemetrexed (Alimta)
- Ramucirumab (Cyramza) combined with docetaxel
- Nintedanib (Vargatef) combined with docetaxel
- Paclitaxel combined with bevacizumab (Avastin)

Researchers collected information on key patient characteristics that can influence treatment outcomes, including age, sex, smoking status, disease stage, other genetic mutations, histology, performance status (a measure of how well a patient can carry out daily activities), number of metastatic sites, previous treatments received, and PD-L1 expression levels.

### Connecting the Evidence: External Comparator Arms

Because DESTINY-Lung02 tested only T-DXd (a single-intervention design), it could not be connected directly to other trials in a standard network. To overcome this, the researchers created an **external comparator arm (ECA)**. They used detailed patient-level data from two historical NSCLC trials that included a docetaxel treatment arm: the **INTEREST trial** and the **VITAL trial**.

The docetaxel arm from INTEREST was selected for the main (base case) analysis because its patient population aligned better with DESTINY-Lung02 regarding the number of prior therapies. The docetaxel arm from VITAL was used as a sensitivity analysis — a way of checking whether the results were consistent. This was needed because 98.3% of patients in VITAL had received only one prior line of therapy, compared to only 29.5% of T-DXd patients from DESTINY-Lung02.

The researchers used a statistical technique called **propensity score weighting** to balance the patient characteristics between the trials, making the historical patients more comparable to those who received T-DXd. This process helped adjust for differences in age, sex, performance status, smoking history, and other factors linked to prognosis.

### Two Statistical Approaches

The team used two complementary statistical methods:

1.
**Network meta-analysis (NMA)**: This approach combines evidence from multiple trials in a connected network to estimate the relative effects of different treatments. Results were expressed as hazard ratios (HRs) for progression-free survival and overall survival, and odds ratios (ORs) for overall response rate, each with a 95% credible interval (CrI). Results were considered "notably different" if the 95% CrI did not cross 1.
1.
**Matching-adjusted indirect comparisons (MAICs)**: This method also used propensity score weighting to make patient populations more similar across trials. It was used for PFS and OS comparisons and gave results considered significant when the confidence interval (CI) did not include 1.

To make the results easier to interpret: an HR below 1 means the treatment in question is associated with a lower risk of the event (progression or death) than the comparison treatment. An OR above 1 means the treatment is associated with higher odds of response.

A later data cut-off from DESTINY-Lung02 (25 August 2023) became available, so additional MAICs were run as a scenario analysis to confirm the findings held up with more mature data.

## Which Studies Were Included

The literature search identified **91 papers** corresponding to **70 clinical trials**. After applying strict eligibility criteria, **18 randomized controlled trials (RCTs)** were identified for consideration. Five single-arm trials with treatments of interest were also considered for the MAICs, but the researchers ultimately used only the randomized controlled trials because they provide higher-quality evidence.

Of the 18 RCTs, 8 were conducted entirely in non-squamous patients, while the remaining 10 included a mixed histology population. Because most patients in those mixed trials had non-squamous disease, the researchers still considered the populations representative.

After a careful feasibility assessment that examined balance across age, sex, prior lines of therapy, smoking history, disease stage, performance status, EGFR mutation status, and adenocarcinoma histology, **13 trials** were selected for the network meta-analyses and matching-adjusted indirect comparisons. Some patient characteristics differed between trials, including the proportion of male patients and the proportion of patients who had never smoked.

The final evidence network included trials representing many real-world treatment approaches:

-
**KEYNOTE-010**: pembrolizumab versus docetaxel
-
**CheckMate057**: nivolumab versus docetaxel
-
**CheckMate078**: nivolumab versus docetaxel (conducted in China)
-
**OAK** and **POPLAR**: atezolizumab versus docetaxel
-
**REVEL**: ramucirumab plus docetaxel versus docetaxel
-
**IFCT-1103 ULTIMATE**: paclitaxel plus bevacizumab versus docetaxel
-
**SIGN**: gefitinib versus docetaxel
-
**TAILOR**: erlotinib versus docetaxel
-
**LUME-Lung1**: nintedanib plus docetaxel versus docetaxel
-
**DELTA**: docetaxel at 60 mg/m²
-
**HORG**: pemetrexed versus docetaxel
-
**CTONG0806**: pemetrexed versus gefitinib

The network included 12 trials for PFS, 11 for OS, and 8 for ORR. Gefitinib and erlotinib were retained in the network only to maintain its connectivity, not because they were treatments of interest.

Two trials (SIGN and CTONG0806) were removed from the PFS network because their follow-up was too short — 9 months and 10.4 months, respectively.

## Key Findings: How T-DXd Compared to Other Treatments

### T-DXd Delayed Cancer Progression Better Than Every Comparator

T-DXd 5.4 mg/kg was associated with longer progression-free survival than all other treatments in the network. The **probability that T-DXd was the best treatment for PFS was 100%** when compared to each individual comparator.

The hazard ratios for PFS consistently favored T-DXd. The range of benefit was wide but always meaningful:

-
**Versus pemetrexed**: HR 0.15 (95% CrI 0.09 to 0.26), meaning T-DXd reduced the risk of cancer progression by about 85% compared with pemetrexed
-
**Versus paclitaxel plus bevacizumab**: HR 0.33 (95% CrI 0.20 to 0.56), meaning T-DXd reduced the risk of progression by about 67%

The results for other comparators — including the immunotherapies nivolumab, pembrolizumab, and atezolizumab, and the chemotherapy docetaxel — fell between these values, and every comparison favored T-DXd. The 95% credible intervals did not cross 1, which means these findings are statistically robust rather than due to chance.

### Overall Survival Also Favored T-DXd

A similar trend was seen for overall survival. The probability that T-DXd was the best treatment for OS was **at least 59%** across all comparators. The most notable survival difference was seen against paclitaxel plus bevacizumab, with an **HR of 0.54 (95% CrI 0.30 to 0.97)**, meaning patients on T-DXd had roughly a 46% lower risk of death during the study period compared to those on paclitaxel plus bevacizumab. Other overall survival hazard ratios in the analysis ranged up to 0.64 (95% CrI 0.35 to 1.15), and the direction of effect consistently favored T-DXd.

### Dramatically Higher Response Rates

The **overall response rate (ORR)** — the percentage of patients whose tumors shrank significantly or disappeared — was highest with T-DXd at **49%**. That means roughly 1 in 2 patients responded to T-DXd. The odds ratios for response compared to other regimens ranged from **6.09 to 21.14**, representing a multifold increase in the likelihood of tumor shrinkage compared with every other treatment. The probability that T-DXd was the best treatment for ORR was **at least 80%** against all comparators.

### Checking the Results: Were They Consistent?

The researchers performed multiple checks to make sure the results were reliable. Consistent results were obtained using the two different external comparator arms (INTEREST and VITAL) and using the alternative approach of pairwise matching-adjusted indirect comparisons. This consistency strengthens confidence in the findings.

## What This Means for Patients

This review found that T-DXd is associated with a consistent and meaningful benefit in delaying cancer progression, with a favorable overall survival trend, compared with the treatments most commonly used for HER2-mutant NSCLC after first-line therapy fails. For adults with HER2-mutant metastatic non-squamous NSCLC, the authors conclude that T-DXd may be the best treatment option in the second-line or later setting.

These findings matter because patients and oncologists have had little guidance on how T-DXd compares to alternatives like immunotherapy or single-agent chemotherapy. Doctors could recommend immunotherapy or docetaxel for these patients, but the historical results have been modest — roughly 3 to 5 months of progression-free survival. In this analysis, the magnitude of T-DXd's progression benefit was large, with hazard ratios indicating a 67% to 85% risk reduction compared to standard chemotherapy options.

A 49% response rate also matters for quality of life and symptom relief. When a tumor shrinks substantially, patients often feel better and can tolerate additional lines of therapy if needed. The 5.4 mg/kg dose, which is the approved dose, was chosen in part because of its more favorable safety profile compared to the higher 6.4 mg/kg dose tested earlier.

Some additional considerations emerged from the data. The T-DXd group in DESTINY-Lung02 had fewer never-smokers (46% ever-smokers versus about 54% never-smokers), reflecting the biology of HER2-mutant lung cancer, which is more common in people who have never smoked. Despite the imbalance in some baseline characteristics, the benefit of T-DXd remained consistent across statistical methods, which supports the strength of the conclusion.

## Study Limitations

No study is perfect, and the researchers transparently acknowledged several limitations.

First, no trial has directly compared T-DXd with other treatments in HER2-mutant patients. This analysis used indirect methods, which are valuable but less definitive than head-to-head randomized controlled trials. The comparisons relied on linking the DESTINY-Lung02 results to historical trials through a docetaxel "bridge."

Second, HER2 mutation status was not reported or tested in the comparator trials. The researchers could not directly adjust for HER2 mutation. Instead, they took two careful steps: they only included studies of patients who were wild-type for other actionable driver mutations (such as EGFR, ALK, ROS1, MET, or KRAS), and they assessed other characteristics known to correlate with HER2-mutant status, including disease stage, smoking status, sex, age, and concurrent mutations. Still, some unknown differences could remain between the HER2-mutant trial population and the historical trial populations.

Third, brain metastasis rates were not fully balanced. After weighting, brain metastases were more common in the T-DXd arm from DESTINY-Lung02 (38.6%) than in the INTEREST trial population (17.2%). This imbalance would generally make the comparison more conservative — T-DXd achieved its benefit despite treating a group with more brain involvement — but it is still a source of uncertainty.

Fourth, the number of prior treatment lines differed substantially between T-DXd patients and some comparator trials. In the VITAL sensitivity analysis, 70.5% of T-DXd patients had received at least two prior regimens, compared to only 1.4% of docetaxel patients after weighting. Patients with more prior therapies usually have more treatment-resistant disease, which again would tend to work against T-DXd rather than in its favor.

Finally, for overall survival, the probability that T-DXd was the best treatment was at least 59%, which is strong but not as definitive as the 100% probability seen for progression-free survival. Survival data were less mature, and subsequent therapies patients receive after a trial can influence overall survival outcomes.

## Recommendations for Patients and Families

If you or a loved one has been diagnosed with non-small cell lung cancer, especially the non-squamous subtype, here are some practical steps to consider based on this research:

-
**Ask about HER2 testing.** HER2 mutations are found in up to 3% to 5% of NSCLC cases. If your tumor has not been tested for HER2, ask your oncologist whether tumor tissue or a liquid biopsy (a blood test that detects tumor DNA) could be checked.
-
**Know your treatment history.** This study applies to patients who have already received at least one prior systemic therapy, including platinum-based chemotherapy. T-DXd is approved for the second-line or later setting.
-
**Ask about T-DXd specifically.** If you have a HER2-mutant tumor and your disease has progressed after first-line treatment, discuss T-DXd at 5.4 mg/kg every 3 weeks with your oncologist. This analysis suggests it offers the strongest likelihood of delaying progression compared to chemotherapy or immunotherapy options.
-
**Understand expected benefits in real numbers.** About 49% of patients on T-DXd had their tumors shrink, compared to substantially lower rates on other regimens — the odds of response were 6 to 21 times higher on T-DXd. The risk of cancer progression was reduced by roughly 67% to 85% compared to standard chemotherapies in this analysis.
-
**Discuss side effects.** T-DXd, like all cancer treatments, has side effects. The 5.4 mg/kg dose was chosen because of its more favorable safety profile. Ask your doctor about the specific risks, including nausea, fatigue, and the rare but serious risk of drug-related lung inflammation (interstitial lung disease).
-
**Ask about brain metastases.** The pooled data from DESTINY-Lung01 and DESTINY-Lung02 suggest T-DXd has activity in the brain, and having brain metastases at baseline did not reduce the systemic response. If you have brain involvement, ask your doctor whether T-DXd may be appropriate for you.
-
**Consider clinical trials when possible.** Indirect comparisons are useful, but a direct head-to-head trial would provide even stronger evidence. Ask your oncologist whether any trials are enrolling HER2-mutant NSCLC patients in your region.

The takeaway message for patients is encouraging. For the first time, a targeted therapy is available that appears to outperform the older standard options for HER2-mutant lung cancer in the second-line setting and beyond. This systematic review — despite its limitations — consistently found T-DXd to be the most effective option across every outcome measured, with the strongest certainty for progression-free survival.

## Frequently Asked Questions

### What is T-DXd (Enhertu) for HER2-mutant lung cancer?

T-DXd is an antibody-drug conjugate that targets HER2 on cancer cells and delivers chemotherapy directly to them. For adults with HER2-mutant advanced non-small cell lung cancer who need second-line treatment or later, this analysis suggests it may offer stronger benefit than other options.

### Which patients does this research apply to?

Adults with non-squamous advanced or metastatic non-small cell lung cancer that has an activating HER2 mutation. Their disease must have progressed after at least one prior therapy, including platinum-based chemotherapy. Most patients in the key trial had received two or more prior treatments.

### How do response rates with T-DXd compare with other treatments?

In this analysis, about 49% of patients on T-DXd had their tumors shrink. The odds of response were 6 to 21 times higher with T-DXd than with other regimens, including immunotherapy and chemotherapy. The probability that T-DXd was most effective for response was at least 80%.

### What side effects of T-DXd should I discuss with my doctor?

T-DXd can cause nausea, fatigue, and a rare but serious risk of drug-related lung inflammation called interstitial lung disease. The approved dose of 5.4 mg/kg every three weeks was chosen due to its more favorable safety profile compared with a higher dose.

### Does T-DXd work if lung cancer has spread to the brain?

Pooled data from two trials suggested T-DXd has activity in the brain. The presence of brain metastases at the start did not reduce how well the drug worked systemically. If you have brain involvement, ask your oncologist whether T-DXd may be appropriate.

### Should I get a second opinion before starting trastuzumab deruxtecan (Enhertu) for HER2-mutant lung cancer after my first treatment failed?

For HER2-mutant non-squamous non-small cell lung cancer that has progressed after at least one prior therapy, trastuzumab deruxtecan (Enhertu) at 5.4 mg/kg every three weeks is a guideline-recommended option. A second opinion can confirm that HER2 mutation testing included tumor tissue or liquid biopsy, clarify whether your treatment history matches the second-line or later setting, and review side-effect risks, including interstitial lung disease. It can also explore whether clinical trials are available. Independent review of your pathology, imaging, and treatment history may help you feel confident in this treatment decision. Diagnostic Detectives Network provides independent expert second opinions.

## Source Information

**Original article title:** Comparative efficacy of trastuzumab deruxtecan versus guideline-recommended treatments for 2L+ unresectable locally advanced or metastatic HER2-mutant non-small cell lung cancer: a systematic review and indirect treatment comparison.

**Authors:** Cappuzzo F, Zhang L, Dunton K, Dennis N, Le Nouveau P, Nevière A, Gauthier A.

**Journal:** Frontiers in Oncology, volume 15, article 1708245.

**Publication date:** 13 February 2026. **DOI:** 10.3389/fonc.2025.1708245

The study was affiliated with the National Cancer Institute Regina Elena (Rome, Italy), Daiichi Sankyo (the manufacturer of Enhertu), and Amaris Consulting. It received review from clinicians at Instituto Oncológicas in Brazil and Azienda Sanitaria Locale Salerno in Italy. The trial data underlying the analysis came from DESTINY-Lung02 (NCT04644237), DESTINY-Lung01 (NCT03505710), INTEREST, VITAL, and the other registered clinical trials listed in this article.

*Note: This patient-friendly article is based on peer-reviewed research. It is provided for educational purposes and does not replace individualized medical advice from your oncology care team. Always discuss your specific diagnosis, treatment options, and any questions about this research with your doctor.*


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