Who is this for?
This is for people with HER2-positive, advanced stomach or gastroesophageal-junction cancer whose cancer has grown after a first round of treatment (a “second-line” setting).
About 1 in 6 stomach cancers are “HER2-positive,” meaning the cancer cells carry extra copies of a protein called HER2 on their surface — which acts like a target that certain drugs can home in on.
What kind of trial is this?
DESTINY-Gastric04 was an international phase III randomized trial — the most rigorous kind. It compared T-DXd against standard second-line chemotherapy in people whose HER2-positive stomach cancer had progressed after first-line trastuzumab-based treatment.
Background: chemotherapy delivered to the target
Ordinary chemotherapy floods the whole body, hitting healthy cells as well as cancer. An antibody–drug conjugate works differently: it clips a chemotherapy payload onto an antibody that seeks out a specific marker — here, HER2 — so the chemo is delivered into the cancer cells that carry it. T-DXd had already transformed HER2-positive breast cancer; this trial tested it as a second treatment for HER2-positive stomach cancer.
The trial: what was tested and how
DESTINY-Gastric04 enrolled 494 people with HER2-positive stomach or GEJ cancer that had progressed after first-line trastuzumab-based treatment. They were randomly assigned to one of two treatments:
- Trastuzumab deruxtecan (T-DXd) (246 people): by infusion every 3 weeks.
- Ramucirumab + paclitaxel (248 people): the standard second-line chemotherapy combination.
The main measure was how long people lived (overall survival).
Results: what they found
T-DXd helped people live longer and shrank the cancer more often — with one important side effect to watch for.
Trastuzumab deruxtecan vs standard chemotherapy
People lived about 3 months longer on average — a 30% lower risk of death (HR 0.70).
The tumor measurably shrank in far more people — a sign the targeted delivery hits harder where it counts.
T-DXd can cause inflammation of the lungs. Most cases were mild, but it can rarely be serious, so it is watched for closely (new cough or breathlessness is reported promptly). Overall, serious side effects were about as common as with standard chemo.
What is an antibody–drug conjugate?
It’s a two-part drug: an antibody that recognizes a specific marker on cancer cells (here, HER2), joined to a chemotherapy “payload.” The antibody delivers the chemo directly into the marked cancer cells, concentrating it where it’s needed and sparing more of the body — a bit like a guided missile compared with carpet-bombing. Our DESTINY-Breast05 summary explains the same drug and this design in more detail.
Why does the lung inflammation matter?
Interstitial lung disease (ILD), or pneumonitis, is the signature risk of T-DXd. Most cases are mild and manageable if caught early, but it can occasionally become serious, so care teams monitor for it and act quickly on new breathing symptoms. This is a real trade-off to weigh against the drug’s clear benefits — and a reason close follow-up matters.
The bottom line
For HER2-positive stomach cancer that has grown after first treatment, trastuzumab deruxtecan — a targeted “smart bomb” chemotherapy — helped people live longer than standard second-line chemotherapy (median 14.7 vs 11.4 months) and shrank the tumor far more often (44% vs 29%). Its main distinctive risk is lung inflammation, usually mild but requiring close attention. It confirms this targeted drug as a strong second-line option for HER2-positive stomach cancer.
What this could mean for you
- HER2 testing matters. Knowing whether a stomach cancer is HER2-positive opens up this targeted option — ask whether your tumor was tested.
- Targeted delivery. The drug carries chemotherapy directly to HER2-marked cells rather than flooding the body.
- Watch the lungs. Report any new cough or shortness of breath promptly — early action on lung inflammation is important.
- A meaningful second-line gain. After first-line treatment stops working, this offers a longer, more effective option than the older standard.
Questions & comments
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