Antibody-Drug Conjugate (ADC) Clinical Trials by the Numbers (2026)

Antibody-drug conjugates (ADCs) have emerged as one of the most clinically and commercially significant modalities in modern oncology. By linking a monoclonal antibody directed against a specific tumor antigen to a cytotoxic payload via a chemical linker, ADCs aim to deliver highly potent cell-killing agents directly to tumor cells while minimizing systemic toxicity. To map the global development landscape of this therapeutic class, we conducted a comprehensive, reproducible analysis of the ClinicalTrials.gov registry (snapshot dated July 9, 2026, encompassing 593,126 registered studies — see our broader ClinicalTrials.gov registry by the numbers for the full-study landscape).

Our analysis identified a specific cohort of 1,615 antibody-drug conjugate clinical trials globally, spanning all clinical phases and tumor indications. The data reveals an industry undergoing rapid acceleration: annual trial starts rose from 88 in 2020 to a peak of 212 in 2025, with 197 new trials initiated in 2026 through the July snapshot date. However, the data also highlights significant clinical concentration: a single target antigen, HER2, accounts for more than 20% of the entire pipeline, and a small group of biopharmaceutical companies dominates industrial sponsorship.

How many ADC clinical trials are there, and is the field still growing?

The ADC development pipeline has grown exponentially over the past decade. Of the 593,126 trials in the registry, 1,615 are specifically focused on therapeutic ADCs (excluding diagnostic imaging agents and radiopharmaceuticals).

Longitudinal Growth and Annual Trial Starts

The annual run-rate of new ADC clinical trial starts demonstrates a sustained oncology "gold rush." Between 2018 and 2025, the number of new trials initiated annually grew by more than 220%.

The 197 trial starts recorded in the first half of 2026 indicate that the full-year total for 2026 is projected to eclipse 300, setting a new historical record. This growth is driven by the clinical success and commercial traction of approved ADCs, the expansion of existing agents into earlier lines of therapy (such as adjuvant and neoadjuvant settings), and a massive influx of venture capital and licensing deals targeting next-generation linker-payload platforms.

Clinical Phase Distribution and Trial Status

The distribution of ADC trials across clinical phases indicates a pipeline that is maturing but remains heavily weighted toward early-to-mid-stage exploration.

• Phase 2: 733 trials (45.4% of the cohort)
• Phase 1/2 (Combined): 233 trials (14.4%)
• Phase 1: 218 trials (13.5%)
• Phase 3: 194 trials (12.0%)
• Not Applicable (NA): 175 trials (10.8%—typically investigator-initiated trials or pilot safety studies)
• Phase 2/3 (Combined): 26 trials (1.6%)
• Phase 4: 24 trials (1.5%)
• Early Phase 1: 12 trials (0.7%)

The large volume of Phase 2 and Phase 1/2 trials represents a significant clinical development bottleneck. Hundreds of candidates are currently competing for a limited pool of trial sites and oncology patients.

The median enrollment across the entire 1,615-trial cohort is 60 patients, reflecting the target-specific, biomarker-selected nature of modern ADC development. However, enrollment varies widely by phase, ranging from a median of 24 patients in Phase 1 safety trials to over 600 patients in Phase 3 registrational trials.

In terms of recruitment status, the pipeline remains highly active:

• Recruiting: 520 trials (32.2%)
• Completed: 376 trials (23.3%)
• Active, Not Recruiting: 225 trials (13.9%)
• Not Yet Recruiting: 187 trials (11.6%)
• Terminated: 121 trials (7.5%)
• Unknown Status: 107 trials (6.6%)
• Withdrawn: 53 trials (3.3%)
• Suspended/Other: 26 trials (1.6%)

The 7.5% termination rate (121 trials) and 3.3% withdrawal rate (53 trials) underscore the significant clinical risk of the modality. The primary drivers of ADC trial terminations are off-target toxicities (such as interstitial lung disease, neutropenia, ocular toxicities, and peripheral neuropathy), unstable linkers leading to premature payload release in systemic circulation, and insufficient efficacy compared to rapidly evolving standards of care.

Which targets are overcrowded, and where are the white spaces?

A major challenge facing ADC developers in 2026 is target-antigen overcrowding. Our analysis of the cohort’s antigen specificity reveals that a handful of well-characterized tumor markers account for the vast majority of clinical development, while dozens of novel antigens remain under-explored.

Target Antigen Concentration

We mapped the specific target antigens across the 1,615-trial cohort using a keyword-based classification of study titles, conditions, and interventions.

The HER2 Overcrowding Problem

With 354 trials, HER2 is the target for 21.9% of all ADC clinical trials in history. This concentration is a direct result of the clinical success of Kadcyla (ado-trastuzumab emtansine) and the landmark approval of Enhertu (trastuzumab deruxtecan), which established new standards of care in HER2-positive and HER2-low breast cancer.

For developers, the HER2 market is intensely saturated. A new HER2-targeted ADC faces a high bar: it must not only show efficacy, but must also demonstrate superiority or a significantly improved safety profile compared to Enhertu, which has already established a dominant position across multiple solid tumors. The high volume of active HER2 trials (many of which are investigator-initiated studies combining Enhertu or Kadcyla with novel immunotherapies, tyrosine kinase inhibitors, or radiotherapies) makes patient recruitment for new HER2 compounds exceptionally difficult.

Emerging Targets and White Spaces

In contrast to the crowded HER2 lane, several high-potential antigens have relatively small clinical footprints:

• TROP2: Despite only having 19 clinical trials in this registry cohort, TROP2 is the target for Trodelvy (sacituzumab govitecan) and the recently approved Datroway (datopotamab deruxtecan). The low trial count relative to HER2 suggests that TROP2 development is highly concentrated within a few major sponsors, leaving significant room for differentiated, next-generation TROP2 programs with novel linkers or alternative payloads.
• B7-H3 (CD276): A checkpoint molecule overexpressed in a wide range of solid tumors (including prostate, lung, and esophageal cancers) but rarely expressed in normal tissues. B7-H3 has only 4 trials in our registry cohort, representing a major pipeline white space. Daiichi Sankyo's DS-7300a is currently in Phase 3 development, but the competitive landscape remains open.
• Claudin 18.2: Highly specific to gastric and pancreatic lineages. While it has only 3 trials in this cohort, Claudin 18.2 is the target of multiple early-stage licensing deals and represents a key growth area for gastrointestinal oncology.

Which sponsors are running the most ADC trials?

The sponsorship of ADC clinical trials is split between commercial biopharmaceutical sponsors (Industry) and academic or cooperative groups (Other/NIH).

Sponsor Class Split

Of the 1,615 trials in the cohort:

• Academic / Other: 883 trials (54.7%) — Led by major cancer centers, university hospitals, and cooperative groups (e.g., Eastern Cooperative Oncology Group, Alliance for Clinical Trials in Oncology).
• Industry: 632 trials (39.1%) — Funded and executed directly by commercial biopharmaceutical firms.
• National Institutes of Health (NIH): 53 trials (3.3%) — Sponsored by the US National Cancer Institute (NCI) and other federal agencies.
• Network: 37 trials (2.3%) — Conducted by national clinical trial networks.
• Other Government: 9 trials (0.6%)
• Federal (non-NIH): 1 trial (0.1%)

The high proportion of academic-sponsored trials (54.7%) indicates that while biopharma companies hold the commercial rights to approved assets, academic investigators are driving the clinical optimization of these drugs. Academic trials frequently evaluate approved ADCs in novel combination regimens, alternative dosing schedules, or off-label indications.

Top Industrial and Institutional Sponsors

To identify the true commercial leaders in the ADC space, we analyzed the top individual sponsors within the cohort.

Pfizer’s Consolidated Dominance

While Merck Sharp & Dohme leads the single-entity list with 58 trials (largely focused on combining Keytruda with various partner ADCs), a consolidated view of sponsorship reveals that Pfizer is the largest commercial sponsor in the ADC category.

Following its $43 billion acquisition of Seagen Inc. in late 2023, Pfizer consolidated Seagen's extensive ADC pipeline. By combining:

• Pfizer (Parent Entity): 29 trials
• Seagen Inc. (Legacy entity): 36 trials
• Seagen (wholly owned subsidiary of Pfizer): 16 trials

Pfizer controls a consolidated portfolio of 81 ADC clinical trials, far outpacing Merck, Roche, and Daiichi Sankyo. This consolidated portfolio includes the commercial assets Adcetris (CD30), Padcev (Nectin-4), Tivdak (Tissue Factor), and Besponsa (CD22), alongside a deep pipeline of early-stage assets utilizing next-generation payloads.

How many ADCs are approved, and which payloads/linkers dominate?

As of mid-2026, the FDA has approved 15 antibody-drug conjugates for clinical use. The class has expanded from hematologic malignancies (which characterized early approvals like Mylotarg and Adcetris) into major solid tumors, including breast, bladder, lung, and cervical cancers. (For the payer side of these approved agents — formulary coverage, cost, and prior authorization — see our ADC access landscape.)

The 15 FDA-Approved ADCs

The approved list reflects the progression of ADC technology over the past quarter-century:

1. Mylotarg (gemtuzumab ozogamicin - Pfizer): Approved 2000, withdrawn 2010 due to safety concerns, re-approved 2017. Targets CD33 with a calicheamicin payload.
2. Adcetris (brentuximab vedotin - Pfizer/Seagen): Approved 2011. Targets CD30 with a monomethyl auristatin E (MMAE) payload.
3. Kadcyla (ado-trastuzumab emtansine - Roche): Approved 2013. Targets HER2 with a DM1 payload.
4. Besponsa (inotuzumab ozogamicin - Pfizer): Approved 2017. Targets CD22 with a calicheamicin payload.
5. Polivy (polatuzumab vedotin-piiq - Roche): Approved 2019. Targets CD79b with an MMAE payload.
6. Padcev (enfortumab vedotin-ejfv - Astellas/Pfizer): Approved 2019. Targets Nectin-4 with an MMAE payload.
7. Enhertu (trastuzumab deruxtecan-nxki - Daiichi Sankyo/AstraZeneca): Approved 2019. Targets HER2 with a DXd (topoisomerase-I inhibitor) payload.
8. Trodelvy (sacituzumab govitecan-hziy - Gilead): Approved 2020. Targets TROP2 with an SN-38 payload.
9. Blenrep (belantamab mafodotin-blmf - GSK): Approved 2020, withdrawn November 2022, re-approved October 2025 (with bortezomib and dexamethasone) based on the DREAMM-7 and DREAMM-8 Phase 3 trials in relapsed/refractory multiple myeloma. Targets BCMA with an MMAF payload.
10. Zynlonta (loncastuximab tesirine-lpyl - ADC Therapeutics): Approved 2021. Targets CD19 with a pyrrolobenzodiazepine (PBD) dimer payload.
11. Tivdak (tisotumab vedotin-tftv - Pfizer/Genmab): Approved 2021. Targets Tissue Factor with an MMAE payload.
12. Elahere (mirvetuximab soravtansine-gxnx - AbbVie/ImmunoGen): Approved 2022. Targets Folate Receptor Alpha with a DM4 payload.
13. Datroway (datopotamab deruxtecan-dlnk - Daiichi Sankyo/AstraZeneca): Approved 2025. Targets TROP2 with a DXd payload. Approved for HR+/HER2− breast cancer and EGFR-mutated NSCLC.
14. Emrelis (telisotuzumab vedotin-tllv - AbbVie): Approved 2025. Targets c-Met with an MMAE payload. Approved for c-Met-overexpressing squamous and non-squamous NSCLC.
15. Lumoxiti (moxetumomab pasudotox-tdkb - AstraZeneca): Approved 2018 for relapsed/refractory hairy cell leukemia. CD22-directed, carrying a Pseudomonas exotoxin (PE38) payload rather than a conventional small-molecule toxin, it was the first non-chemotherapy option approved for the disease. It has since been discontinued from the U.S. market, illustrating how early immunoconjugate entrants can be overtaken by newer payloads and combination regimens.

(Note: Disitamab vedotin, brand name Aidixi, targeting HER2 with an MMAE payload, is approved and marketed in China by RemeGen but is not yet FDA-approved as a monotherapy, though it is licensed globally by Seagen/Pfizer and is in active U.S. Phase 3 trials).

Linker-Payload Chemistry Trends

The therapeutic index of an ADC—the margin between the dose that kills tumor cells and the dose that causes unacceptable systemic toxicity—is largely determined by its linker-payload chemistry. Payloads currently in clinical trials fall into three dominant classes:

1. Microtubule Inhibitors (Auristatins and Maytansinoids):
   • Agents: MMAE, MMAF, DM1, DM4.
   • Mechanism: Block mitosis by inhibiting tubulin polymerization.
   • Examples: Adcetris, Kadcyla, Polivy, Padcev, Tivdak, Elahere, Emrelis.
   • Clinical Profile: Highly potent, but associated with peripheral neuropathy, neutropenia, and ocular toxicity (particularly DM4).
2. Topoisomerase-I Inhibitors (Camptothecin Derivatives):
   • Agents: DXd (deruxtecan), SN-38.
   • Mechanism: Induce DNA double-strand breaks by stabilizing topoisomerase-I-DNA cleavable complexes.
   • Examples: Enhertu, Trodelvy, Datroway.
   • Clinical Profile: Excellent bystander-killing effect (ability to diffuse out of the target cell and kill adjacent tumor cells, regardless of antigen expression), making them highly effective in heterogeneous tumors. However, they carry risks of interstitial lung disease (ILD) and neutropenia.
3. DNA-Damaging Agents (Calicheamicins and Alkylating Agents):
   • Agents: Calicheamicin, PBD (pyrrolobenzodiazepine) dimers.
   • Mechanism: Bind to the minor groove of DNA, causing double-strand cleavage or cross-linking.
   • Examples: Mylotarg, Besponsa, Zynlonta.
   • Clinical Profile: Extremely high potency, but associated with severe myelosuppression and hepatic sinusoidal obstruction syndrome (SOS / VOD).

External Landscape Comparison

An external cross-check against commercial databases (such as the Patsnap Eureka competitive intelligence tracker, June 2026 update) reports a total of 2,868 ADC drug records globally, including preclinical candidates, discontinued programs, and patented sequences, alongside 1,519 ongoing Phase 2/3 clinical trials globally.

This difference in numbers highlights our specific filtering methodology: our ClinicalTrials.gov registry cohort (1,615 trials) captures all-time registered clinical trials (active, completed, terminated, and withdrawn) within the U.S. national registry. In contrast, commercial databases capture global, multi-registry clinical trials and include preclinical, discovery-stage patent records.

Disclosing this cohort difference is essential for biopharma strategists: the registry cohort represents the verified, clinically active footprint of human testing, whereas commercial trackers include substantial preclinical and intellectual-property noise.

What does the ADC trial concentration mean for BD and competitive strategy?

The data from our 1,615-trial cohort points to several key strategic imperatives for biopharmaceutical business development (BD) and pipeline planning teams.

1. The Necessity of Bystander Killing in Solid Tumors

The transition of the ADC market from hematologic targets (which are typically homogeneous) to solid tumors (which are highly heterogeneous) has redefined the required payload characteristics. Topoisomerase-I inhibitor payloads like DXd and SN-38 have gained market share because their moderate potency and high membrane permeability allow them to exert a potent "bystander effect." This allows the ADC to clear antigen-negative tumor cells within the microenvironment, a critical advantage in breast, lung, and colorectal cancers where antigen expression is highly variable.

2. Strategic Pivoting to White Space Antigens

With 354 trials targeting HER2, developers should avoid initiating new HER2-directed programs unless they possess a demonstrably superior platform (e.g., site-specific conjugation with a drug-to-antibody ratio [DAR] of exactly 8, or a novel bispecific format). Instead, BD teams should target emerging antigens like B7-H3, Claudin 18.2, or DLL3, where the clinical competitive landscape is less crowded and the opportunity to secure first-in-class or best-in-class status remains open.

3. Combination Strategy is the Primary Battleground

Given that over 54% of ADC trials are academically sponsored and often evaluate combinations, developers must actively secure combination partnerships. The clinical trial space is dominated by studies combining ADCs with immune checkpoint inhibitors (such as Merck's Keytruda or Roche's Tecentriq). An ADC developer without a clear checkpoint combination strategy will struggle to compete in front-line solid tumor indications.

4. Manufacturing and Quality Control Scale-Up Complexity

A critical watch-item that is often overlooked in early clinical phases is the chemistry, manufacturing, and controls (CMC) complexity. Setting up a commercial supply chain for an ADC requires:

• Monoclonal Antibody Production: Typically produced in mammalian cell lines, requiring sterile bioreactor capacity.
• Payload Synthesis: Highly potent active pharmaceutical ingredients (HPAPIs) requiring specialized containment facilities to protect operators.
• Conjugation and Purification: Joining the antibody and payload using site-specific or random conjugation chemistry, followed by extensive purification to remove unconjugated antibody and free payload.
• DAR Homogeneity: Achieving a consistent Drug-to-Antibody Ratio (DAR). Random conjugation results in a mixture of species (DAR 0 to 8+), which can compromise efficacy or increase toxicity. Next-generation platforms focus on site-specific conjugation (e.g., using engineered cysteines or unnatural amino acids) to achieve a uniform DAR, typically of 4 or 8.

Frequently Asked Questions

How are ADC clinical trials counted in this analysis, and what are the limitations?

ADC clinical trials were identified from a ClinicalTrials.gov snapshot (July 9, 2026, 593,126 total studies) using a search query targeting terms such as "antibody-drug conjugate," "antibody drug conjugate," "immunoconjugate," and the generic names of all approved and clinical-stage ADCs across the title, conditions, and interventions fields. Limitations include the fact that the registry is U.S.-centric (though it captures all global trials intended to support FDA approvals), and keyword-based queries may occasionally exclude early Phase 1 trials that do not explicitly declare their conjugation chemistry in public fields.

Which companies have the deepest ADC pipelines in 2026?

Pfizer possesses the deepest consolidated ADC pipeline in 2026, controlling 81 clinical trials through its acquisition of Seagen. Other commercial pipeline leaders include Merck Sharp & Dohme (58 trials), Hoffmann-La Roche (49 trials), Daiichi Sankyo (47 trials), and AstraZeneca (41 trials).

Why is HER2 so dominant in ADC trials?

HER2 is the target for 354 clinical trials (21.9% of the cohort) due to the commercial success and clinical validation of Kadcyla and Enhertu. These drugs proved that HER2 is an ideal target for internalizing ADCs, leading to a massive wave of "me-too" candidates, combination trials, and investigator-initiated studies trying to replicate or extend this clinical benefit.

How does this ADC trial count compare to external trackers?

Our registry count of 1,615 trials reflects verified human clinical trials registered on ClinicalTrials.gov. External trackers (such as Patsnap, which reports over 2,800 ADC drug records) include preclinical compounds, patent filings, and trials registered on secondary international registries (such as China's CTR or Japan's JAPIC) that may not be cross-listed in the U.S. registry.

What are the common endpoints used in ADC registrational trials?

In hematologic oncology, common endpoints include Overall Response Rate (ORR) and Complete Response (CR) rate. In solid tumors, Progression-Free Survival (PFS) and Overall Survival (OS) remain the gold standard endpoints for registrational Phase 3 trials. For accelerated approvals, ORR and Duration of Response (DOR) are frequently accepted, subject to post-marketing confirmatory trials.

Sources

• U.S. National Institutes of Health (NIH) ClinicalTrials.gov: Database of Clinical Trials, Registry Snapshot July 9, 2026. URL: clinicaltrials.gov.
• Novel Drug Approvals at FDA: Novel Drug Approvals for 2025 and 2026, U.S. Food and Drug Administration. URL: fda.gov.
• BiopharmaSpec: "FDA-Approved Antibody Drug Conjugates: Full 2026 List," January 2026. URL: biopharmaspec.com.
• BiochemPEG: "FDA Approved Antibody-Drug Conjugates (ADCs) By 2026," March 2026. URL: biochempeg.com.
• Patsnap Eureka Life Science Blog: "ASCO 2026: Antibody-Drug Conjugate (ADC) Competitive Landscape Analysis," June 2026. URL: eureka.patsnap.com.
• Cell (2026): "Navigating the clinical progress of antibody-drug conjugates," Volume 189, Issue 4, pp. 812-835. URL: cell.com.