What is a clinical trial?

A clinical trial is a research study involving human participants designed to evaluate medical interventions — such as drugs, devices, or behavioral strategies. Trials follow a structured protocol and are registered on ClinicalTrials.gov. They progress through phases: Phase 1 (safety), Phase 2 (efficacy), Phase 3 (large-scale comparison), and Phase 4 (post-market surveillance).

How do I find clinical trials I'm eligible for?

You can search ClinicalTrials.gov or use ClinicalMetric to filter by condition, phase, or location. Each trial listing includes eligibility criteria such as age range, sex, diagnosis, and prior treatment history. Contact the study team directly or ask your physician to refer you to a relevant trial.

Are clinical trials safe to participate in?

Clinical trials are conducted under strict ethical and regulatory oversight, including IRB approval and FDA regulation in the US. All participants must give informed consent after reviewing potential risks and benefits. Phase 1 trials carry more uncertainty, while Phase 3 trials involve interventions with an established safety profile. Participation is always voluntary and you may withdraw at any time.

What are the phases of clinical trials?

Clinical trials progress through four main phases. Phase 1 tests safety and dosing in a small group (20–80 people). Phase 2 evaluates efficacy and side effects in a larger group (100–300). Phase 3 compares the intervention against standard treatments in thousands of participants. Phase 4 occurs after approval and monitors long-term effects in the general population.

Do participants get paid for joining clinical trials?

Many clinical trials offer compensation for time and travel expenses, though payment structures vary widely by study. Compensation is not intended to be coercive. Some trials also cover treatment costs for participants. Always review the consent form carefully and ask the study coordinator about any financial considerations before enrolling.

Breast Cancer Clinical Trials 2026: ADCs, Immunotherapy & Targeted Therapies

Medical Notice

This article is for informational purposes only and does not constitute medical advice. Clinical trial eligibility and availability vary. Always consult a qualified healthcare professional before making any medical decisions or considering participation in a clinical trial.

Summary

Breast cancer is the most commonly diagnosed cancer globally, and clinical research in 2026 reflects its complexity — with fundamentally different treatment approaches for HR+/HER2−, HER2+, and triple-negative subtypes. Antibody-drug conjugates (ADCs) have transformed treatment for HER2-low and TNBC, and are now being moved into earlier lines of treatment in active trials. PARP inhibitors, CDK4/6 inhibitors, and immunotherapy combinations are all being refined. This guide explains the current trial landscape by subtype.

HR+/HER2− Breast Cancer Trials

Hormone receptor-positive, HER2-negative breast cancer accounts for about 70% of all breast cancer. CDK4/6 inhibitors (palbociclib, ribociclib, abemaciclib) are now standard of care in combination with endocrine therapy. Current trials are focused on:

Overcoming CDK4/6 inhibitor resistance — next-generation CDK inhibitors and PI3K/AKT pathway drugs
Capivasertib (AKT inhibitor) + fulvestrant — approved in 2023, now being studied in earlier settings
Elacestrant (oral SERD) — first oral selective estrogen receptor degrader approved, Phase 3 trials in earlier lines ongoing
ADCs — trastuzumab deruxtecan (T-DXd) showed efficacy even in HER2-low tumors, trials expanding this finding

HER2+ Breast Cancer Trials

HER2-positive breast cancer has seen dramatic improvements in outcomes over the past decade. Current trials focus on de-escalation (identifying patients who can receive less treatment without compromising outcomes) and treatment of residual disease after neoadjuvant therapy. Trastuzumab deruxtecan (Enhertu) continues to be studied in multiple settings after transforming the HER2+ and HER2-low landscape. HER2-directed bispecific antibodies and CAR-T cell therapies are entering Phase 1/2 trials.

Triple-Negative Breast Cancer (TNBC) Trials

TNBC — which lacks hormone receptors and HER2 overexpression — was historically the hardest subtype to treat. Several breakthroughs have changed this:

Immunotherapy: Pembrolizumab + chemotherapy is now standard for PD-L1+ metastatic TNBC. Trials are testing new checkpoint combinations
Sacituzumab govitecan (Trodelvy): TROP2-directed ADC approved for metastatic TNBC, now in trials for earlier settings
PARP inhibitors: Olaparib and talazoparib for BRCA1/2-mutated TNBC — combination trials with immunotherapy actively recruiting
mRNA cancer vaccines: Personalized neoantigen vaccines (Moderna/Merck mRNA-4157) in Phase 3 for high-risk TNBC after surgery

Key Biomarkers for Trial Eligibility

Before searching for breast cancer trials, know your tumor's biomarker profile: ER/PR/HER2 status, BRCA1/2 germline mutation status, PIK3CA mutation status, PD-L1 CPS score, and HER2-low designation (IHC 1+ or 2+/ISH−). Comprehensive genomic profiling (Foundation One CDx, Tempus xT) can identify additional targetable alterations. Many trials require or offer this testing at screening.