Why TROP2 Antibody-Drug Conjugates Are in Cancer News

Three parts, bolted together

An antibody-drug conjugate is built from three pieces, and knowing them makes the headlines readable.

The antibody finds a target protein on the surface of a cell. The payload is a cell-killing drug. On its own it would be far too toxic to give. The linker joins the two. It is meant to hold until the whole package has been pulled inside the target cell.

TROP2 is the target here. It is a protein that sits on the surface of many cancer cells. Both approved TROP2 ADCs use the same phrase on the label: a Trop-2-directed antibody and topoisomerase inhibitor conjugate. Topoisomerase inhibitors are an old chemotherapy class. They break the machinery a cell uses to copy its DNA.

So an ADC is not an alternative to chemotherapy. It is chemotherapy with a delivery address. Our page on targeted therapy compared with chemotherapy sets out the line that this class blurs.

What is actually approved

Two TROP2 ADCs carry FDA labels.

Trodelvy, sacituzumab govitecan, covers locally advanced or metastatic triple-negative breast cancer in several settings. One is first-line use for people who are not candidates for PD-1 or PD-L1 inhibitor therapy. Another is second line or later, after two or more prior systemic therapies. The label also covers hormone receptor-positive, HER2-negative breast cancer, after endocrine therapy and at least two further systemic treatments.

Datroway, datopotamab deruxtecan, covers EGFR-mutated non-small cell lung cancer after prior EGFR-directed therapy and platinum chemotherapy, plus two breast cancer settings.

Read those indications closely and a pattern appears. Every one names a specific cancer, a specific receptor status, and a specific place in the treatment sequence. None says "TROP2-positive cancer."

The evidence that got Trodelvy there

The ASCENT trial is the clearest example of what a randomized ADC result looks like.

It enrolled 468 people with relapsed or refractory metastatic triple-negative breast cancer and no brain metastases. Half got sacituzumab govitecan. Half got a single chemotherapy drug chosen by their physician. Median age was 54, and all had already had taxanes.

Median progression-free survival was 5.6 months against 1.7 months. Median overall survival was 12.1 months against 6.7 months. Tumors responded in 35% of the ADC group and 5% of the chemotherapy group.

The same paper reports the cost. Neutropenia means very low infection-fighting white cells. A severe drop hit 51% on the ADC against 33% on chemotherapy. Severe diarrhea hit 10% against under 1%. Fever with a dangerously low count hit 6% against 2%.

Trodelvy's label carries a boxed warning, FDA's strongest, for exactly those two problems.

What "investigational" means for sac-TMT

Sacituzumab tirumotecan, also written sac-TMT or MK-2870, is a third TROP2 ADC. It appears in company presentations and conference abstracts, including Merck's ASCO 2026 materials.

It is not FDA approved. ClinicalTrials.gov lists it in phase 2 and phase 3 studies across several cancers. Those include triple-negative breast cancer, non-small cell lung cancer, and hormone receptor-positive breast cancer. Many are still recruiting or awaiting results.

A wide trial program means researchers think the biology is worth testing in several places. It does not mean the drug works in several places. Those are different claims, and press releases rarely keep them apart. Our explainer on clinical trial phases covers what each stage can show.

An approval that was taken back

This is the part most ADC coverage leaves out.

In April 2021, FDA gave sacituzumab govitecan accelerated approval for advanced urothelial cancer. It applied after platinum chemotherapy and a checkpoint inhibitor. FDA's register of withdrawn cancer accelerated approvals lists that indication as withdrawn on 22 November 2024.

Same molecule, same target, different cancer. The confirming evidence did not hold up. That risk is built into accelerated approval. It is also why a response rate in one tumor type says little about another.

How to read an ADC headline

Four questions do most of the work.

Which exact group? Cancer type, receptor status, and how many prior treatments. A result in third-line disease is not a result in first-line disease.

What was the comparison? A single-arm study reporting a response rate cannot tell you whether people lived longer. A randomized trial against real treatment can.

What did it cost? Look for rates of severe low blood counts, severe diarrhea and lung inflammation. Look for how many people stopped the drug because of side effects.

Where was it published? A company announcement, a conference abstract, a peer-reviewed paper and an FDA approval are four different levels of evidence. Only the last one changes what a clinic can prescribe.

What this does not mean

• Being TROP2-directed does not make these drugs interchangeable. Different payloads and different linkers produce different side effects.
• Targeted delivery does not mean side effects are avoided. Both approved labels describe serious toxicity, and one carries a boxed warning.
• An investigational drug appearing in many trials is not an approved drug. Sacituzumab tirumotecan is not approved for any cancer in the United States.
• A withdrawn indication is not a failed drug. Trodelvy remains approved in breast cancer while its urothelial indication is gone.
• No trial headline is a reason to change treatment. That talk belongs with a care team. Our page on questions to ask about a clinical trial is a place to start.

Sources

• openFDA drug label API: TRODELVY (sacituzumab govitecan-hziy)
• openFDA drug label API: DATROWAY (datopotamab deruxtecan-dlnk)
• FDA: Withdrawn Cancer Accelerated Approvals register
• NCBI eutils: ASCENT trial, Bardia et al., N Engl J Med 2021 (PMID 33882206)
• ClinicalTrials.gov API v2: sacituzumab tirumotecan trial records
• Merck: ASCO 2026 oncology portfolio and pipeline research

How this article was prepared

An AI-assisted editorial system helped prepare this page. No named medical reviewer has reviewed it unless one is listed.

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