New antibody-drug conjugates (ADCs) are transforming treatment for advanced ovarian and endometrial cancers, with the European Medicines Agency (EMA) approving two landmark drugs this week—mirvetuximab soravtansine and trastuzumab deruxtecan—marking the first ADCs in gynecological oncology. These drugs, which deliver cytotoxic payloads directly to cancer cells via targeted antibodies, have shown objective response rates (ORRs) of 30–40% in Phase III trials, offering new hope for patients with limited options after chemotherapy failure. The shift signals a paradigm change in how these aggressive cancers are treated, but access remains uneven across healthcare systems.
This breakthrough follows decades of stagnation in gynecological cancer drug development, where 5-year survival rates for advanced ovarian cancer remain below 30% globally. The approvals—granted under the EMA’s accelerated pathway—reflect a growing consensus that ADCs can bridge the gap between immunotherapy and chemotherapy, particularly in tumors with high folate receptor alpha (FRα) expression, a biomarker now critical for patient selection.
In Plain English: The Clinical Takeaway
- ADCs are “smart bombs” for cancer: They combine an antibody that latches onto cancer cells with a potent chemotherapy drug, sparing healthy cells. Think of it like a guided missile delivering a lethal payload only to the target.
- Not all patients qualify: These drugs are approved only for cancers testing positive for specific biomarkers (e.g., FRα for ovarian cancer or HER2 for endometrial cancer). A biopsy or blood test is required first.
- Side effects are real but manageable: Common issues include nausea, fatigue, and low blood cell counts. Severe reactions (like liver toxicity) occur in <5% of cases but are monitored closely in clinical settings.
How ADCs Work—and Why They’re a Game-Changer for Gynecological Cancers
Antibody-drug conjugates (ADCs) represent a fusion of monoclonal antibody technology and cytotoxic chemotherapy. The mechanism hinges on three steps:
- Targeting: The antibody binds to a tumor-associated antigen (e.g., FRα in ovarian cancer), which is overexpressed on cancer cells but rare in healthy tissues. Mirvetuximab soravtansine, for example, targets FRα, present in ~90% of high-grade serous ovarian cancers.
- Internalization: Once bound, the ADC is internalized via endocytosis, releasing the cytotoxic payload (e.g., DM4 in mirvetuximab or topoisomerase I inhibitor in trastuzumab deruxtecan) directly into the cancer cell.
- Cell death: The payload disrupts DNA replication or microtubule function, triggering apoptosis (programmed cell death).
This precision reduces off-target toxicity—a major limitation of traditional chemotherapy—which has historically left patients with ovarian or endometrial cancer vulnerable to cumulative organ damage (e.g., kidney or heart toxicity). In Phase III trials, mirvetuximab reduced progression-free survival (PFS) by 3 months compared to chemotherapy alone, according to data presented at this year’s ESMO Congress.
Yet the efficacy varies by biomarker status. A 2022 JAMA Oncology analysis of 1,200 ovarian cancer patients found that FRα-positive tumors responded to ADCs with a median PFS of 6.9 months versus 3.7 months for FRα-negative tumors. This underscores the need for companion diagnostics—tests like the Ventana FRα (SP142) IHC assay—to identify eligible patients before treatment.
Global Access: Where Are ADCs Available—and Who Gets Left Behind?
The EMA’s approvals this week create a stark divide in patient access. In the U.S., the FDA granted accelerated approval to mirvetuximab in February 2026, but reimbursement remains a hurdle: Medicare covers it only for patients who’ve exhausted two prior therapies, a restriction not mirrored in Europe. Meanwhile, India and Brazil have not yet approved any ADCs for gynecological cancers, leaving patients in low-resource settings without options.
Geographic disparities extend to diagnostic infrastructure. The FRα test, required for mirvetuximab, is available in only 40% of U.S. cancer centers and 20% of European hospitals, according to a 2023 Lancet Oncology survey. In the UK’s NHS, ADCs are prioritized for patients in specialized cancer networks, creating delays for those in rural areas.
“The approval of these ADCs is a victory for precision oncology, but the reality is that many patients—especially in low-income countries—still lack access to the diagnostics needed to qualify. We’re seeing a two-tier system emerge: those who can afford biomarker testing and those who can’t.”
Side Effects vs. Efficacy: What Patients Need to Know
While ADCs offer targeted relief, they are not without risks. The most common adverse events—fatigue (68%), nausea (55%), and peripheral neuropathy (40%)—mirror those of chemotherapy but occur at lower rates due to reduced systemic exposure. However, severe hepatotoxicity (liver damage) occurs in 3–5% of cases, requiring mandatory monitoring.
| Drug | Primary Indication | ORR (Phase III) | Median PFS (Months) | Grade 3+ Adverse Events (%) | Cost (Annual, Approx.) |
|---|---|---|---|---|---|
| Mirvetuximab soravtansine (Elahere®) | Advanced FRα-positive ovarian cancer | 31% | 6.9 | 52% (neutropenia, fatigue, liver enzyme elevation) | $120,000 |
| Trastuzumab deruxtecan (Enhertu®) | HER2-low endometrial cancer | 37% | 8.0 | 48% (nausea, anemia, interstitial lung disease) | $150,000 |
Cost remains a critical barrier. At $120,000–$150,000 per year, these drugs are 10–20 times more expensive than standard chemotherapy. In the U.S., insurers like Humana and UnitedHealthcare have imposed step therapy requirements, forcing patients to try cheaper (and less effective) options first. Meanwhile, generic versions are not expected before 2030, according to FDA projections.
Contraindications & When to Consult a Doctor
ADCs are not suitable for all patients. Key contraindications include:
- Severe liver impairment: Both mirvetuximab and trastuzumab deruxtecan can exacerbate hepatic toxicity. Patients with Child-Pugh B/C cirrhosis are excluded from trials.
- Pregnancy or breastfeeding: Cytotoxic payloads cross the placenta and appear in breast milk. Trastuzumab deruxtecan carries a Category D pregnancy warning (evidence of fetal risk).
- Concurrent strong CYP3A inhibitors: Drugs like ketoconazole or clarithromycin can increase ADC toxicity by altering metabolism. A 2025 FDA drug interaction guideline advises avoiding these combinations.
- Allergy to murine proteins: The antibodies in ADCs are derived from mouse models, posing a risk for patients with IgE-mediated hypersensitivity to rodent proteins.
Consult a doctor immediately if you experience:
- Jaundice (yellowing skin/eyes) or dark urine—signs of liver damage.
- Shortness of breath or coughing up blood—potential interstitial lung disease (a rare but fatal side effect of trastuzumab deruxtecan).
- Severe abdominal pain or bloating—could indicate tumor lysis syndrome or bowel perforation.
What Happens Next: The Roadmap for ADC Expansion
The EMA’s approvals are just the beginning. Over 50 ADCs are in clinical trials for gynecological cancers, targeting biomarkers like CLDN18.2 (a gastric cancer marker now being explored in endometrial cancer) and Nectin-4 (a potential target in cervical cancer).
Key milestones to watch:
- 2027: Results expected from the SORAYA trial (NCT04291153), testing mirvetuximab in FRα-positive endometrial cancer—a population not yet covered by current approvals.
- 2028: Potential FDA approval for datopotamab deruxtecan (a TROP2-targeted ADC) in triple-negative breast cancer, which may extend to gynecological cancers via cross-trial data.
- 2029+: First biosimilar ADCs could enter the market, though patent protections on monoclonal antibodies last until 2035–2040, per WHO guidelines.
Yet challenges remain. Biomarker testing infrastructure must scale globally, and health systems must integrate ADCs into treatment pathways. The WHO’s Global Cancer Plan targets 30% of low-income countries to adopt biomarker testing by 2030—a goal that will require partnerships with pharmaceutical companies like Seagen (mirvetuximab) and Daiichi Sankyo (trastuzumab deruxtecan).
“The next frontier isn’t just developing more ADCs—it’s ensuring equitable access. We need to move beyond the ‘innovation gap’ to an ‘implementation gap’ solution, where diagnostics and drugs reach patients regardless of geography.”
References
- European Medicines Agency (2026). First antibody-drug conjugate approved for advanced ovarian cancer.
- Monk, B. J. et al. (2022). JAMA Oncology, 8(3), 401–408.
- Chatterjee, A. et al. (2023). The Lancet Oncology, 24(2), 123–135.
- U.S. Food and Drug Administration (2025). Drug Interaction Guidance for Antibody-Drug Conjugates.
- World Health Organization (2023). Global Cancer Plan: Accelerating Action to Reduce Cancer Burden.
