Protein / target

Tubulin beta-3 chain

TUBB3Q13509Homo sapiensSwiss-Prot
UniProt: Q13509Ensembl: ENSG00000258947HGNC: HGNC:20772NCBI Gene: 10381
Clinically validated
Therapeutic maturity
25
Approved medicines
30
Clinical trials
Small-molecule tractable
Druggability
Approved Drug

Protein at a glance

Biological role

Structural constituent of cytoskeleton

Primary system

Nervous system

Strongest disease association

complex cortical dysplasia with other brain malformations 1

Genetic evidence · score 0.93

Therapeutic maturity

Clinically validated target

25 approved medicines against this target

Druggability

Small molecule

Open Targets tractability · Approved Drug

Clinical development

25 approved · 62 in clinical development

30 linked trials

Derived from structured UniProt, Open Targets and literature data on this page.

Protein profile

UniProt 2026_02

Canonical identity and biological annotation from UniProt.

Function

Tubulin is the major constituent of microtubules, protein filaments consisting of alpha- and beta-tubulin heterodimers (PubMed:34996871, PubMed:38305685, PubMed:38609661). Microtubules grow by the addition of GTP-tubulin dimers to the microtubule end, where a stabilizing cap forms (PubMed:34996871, PubMed:38305685, PubMed:38609661). Below the cap, alpha-beta tubulin heterodimers are in GDP-bound state, owing to GTPase activity of alpha-tubulin (PubMed:34996871, PubMed:38609661). TUBB3 plays a critical role in proper axon guidance and maintenance (PubMed:20074521). Binding of NTN1/Netrin-1 to its receptor UNC5C might cause dissociation of UNC5C from polymerized TUBB3 in microtubules and thereby lead to increased microtubule dynamics and axon repulsion (PubMed:28483977). Plays a role in dorsal root ganglion axon projection towards the spinal cord (PubMed:28483977)

Subcellular location

Cytoplasm, cytoskeletonCell projection, growth coneCell projection, lamellipodiumCell projection, filopodium
Domains and Gene Ontology detail (28)

Gene Ontology

  • Caxon
  • Ccell periphery
  • Cciliary tip
  • Ccilium
  • Ccytoplasm
  • Cdendrite
  • Cextracellular exosome
  • Cfilopodium
  • Cgrowth cone
  • Cintercellular bridge
  • Clamellipodium
  • Cmicrotubule

450 aa · 50 kDa · 2 isoforms

Biological roles

Reactome v97

What this protein does, drawn together from its UniProt function, Gene Ontology terms and Reactome pathways.

Nuclear receptor signallingReactomeImmune signallingReactome
View supporting evidence

Nuclear receptor signalling

  • ·HSP90 chaperone cycle for steroid hormone receptors (SHR) in the presence of ligand

Immune signalling

  • ·MHC class II antigen presentation
View underlying pathways (25)
Translocation of SLC2A4 (GLUT4) to the plasma membrane
Microtubule-dependent trafficking of connexons from Golgi to the plasma membrane
Gap junction assembly
MHC class II antigen presentation
Separation of Sister Chromatids
Resolution of Sister Chromatid Cohesion
HSP90 chaperone cycle for steroid hormone receptors (SHR) in the presence of ligand
Recruitment of NuMA to mitotic centrosomes
Prefoldin mediated transfer of substrate to CCT/TriC
Formation of tubulin folding intermediates by CCT/TriC
Post-chaperonin tubulin folding pathway
Recycling pathway of L1
Hedgehog 'off' state
Cargo trafficking to the periciliary membrane
Intraflagellar transport

Concepts derived from UniProt GO Reactome — each badge above shows which sources supported that role.

Interaction neighbourhood

STRING v12.0

Proteins with the strongest functional or physical association. Node size and line weight reflect STRING confidence; hover or select a partner to inspect one association.

TUBA1ATUBA1BTUBA4ATUBA1CMAPTTUBAL3TUBA8TUBA3DTUBA3EMAPRE3TUBB3

10 strongest partners — larger node and heavier line mean higher confidence

Functional and physical associations from STRING v12.0. Only associations with this protein are drawn — partner-to-partner links are not part of this evidence.

Drugs targeting this protein

12

Whether each drug engages this protein directly or through a complex, and how many other targets are recorded for it. Direct binders with few recorded targets are listed first.

Colchicine
ApprovedInhibitor

Tubulin inhibitor

Appears in clinical studies involving familial Mediterranean fever, gout, myocardial infarction, Stroke

Acts on a complex — shared with TUBB4B, TUBB1, TUBA4A +11 more · 1 of 15 recorded protein targets — broad pharmacology

polatuzumab vedotin
ApprovedInhibitor

Tubulin inhibitor

Appears in clinical studies involving diffuse large B-cell lymphoma, diffuse large B-cell lymphoma, B-cell non-Hodgkin lymphoma, neoplasm

Acts on a complex — shared with TUBB4B, TUBB1, TUBA4A +11 more · 1 of 16 recorded protein targets — broad pharmacology

Paclitaxel
ApprovedInhibitor

Tubulin inhibitor

Appears in clinical studies involving non-small cell lung carcinoma, breast carcinoma, breast cancer, carcinoma

Acts on a complex — shared with TUBB4B, TUBB1, TUBA4A +11 more · 1 of 15 recorded protein targets — broad pharmacology

tisotumab vedotin
ApprovedInhibitor

Tubulin inhibitor

Appears in clinical studies involving cervical cancer, cervical cancer, cancer, neoplasm

Acts on a complex — shared with TUBB4B, TUBB1, TUBA4A +11 more · 1 of 16 recorded protein targets — broad pharmacology

docetaxel
ApprovedInhibitor

Tubulin inhibitor

Appears in clinical studies involving breast carcinoma, non-small cell lung carcinoma, breast cancer, prostate cancer

Acts on a complex — shared with TUBB4B, TUBB1, TUBA4A +11 more · 1 of 15 recorded protein targets — broad pharmacology

enfortumab vedotin
ApprovedInhibitor

Tubulin inhibitor

Appears in clinical studies involving urothelial carcinoma, transitional cell carcinoma, neoplasm, urinary bladder carcinoma

Acts on a complex — shared with TUBB4B, TUBB1, TUBA4A +11 more · 1 of 16 recorded protein targets — broad pharmacology

mirvetuximab soravtansine
ApprovedInhibitor

Tubulin inhibitor

Appears in clinical studies involving ovarian cancer, ovarian neoplasm, fallopian tube neoplasm, peritoneal neoplasm

Acts on a complex — shared with TUBB4B, TUBB1, TUBA4A +11 more · 1 of 16 recorded protein targets — broad pharmacology

telisotuzumab vedotin
Phase 3Inhibitor

Tubulin inhibitor

Appears in clinical studies involving non-small cell lung carcinoma, non-small cell lung carcinoma, squamous cell lung carcinoma, squamous cell carcinoma

Acts on a complex — shared with TUBB4B, TUBB1, TUBA4A +11 more · 1 of 16 recorded protein targets — broad pharmacology

belantamab mafodotin
ApprovedInhibitor

Tubulin inhibitor

Appears in clinical studies involving plasma cell myeloma, neoplasm, hematopoietic and lymphoid cell neoplasm, smoldering plasma cell myeloma

Acts on a complex — shared with TUBB4B, TUBB1, TUBA4A +11 more · 1 of 16 recorded protein targets — broad pharmacology

disitamab vedotin
Phase 3Disrupting agent

Tubulin disrupting agent

Appears in clinical studies involving breast cancer, urothelial carcinoma, gastric adenocarcinoma, gastroesophageal junction adenocarcinoma

Acts on a complex — shared with TUBB4B, TUBB1, TUBA4A +11 more · 1 of 16 recorded protein targets — broad pharmacology

vinflunine
ApprovedInhibitor

Tubulin inhibitor

Appears in clinical studies involving neoplasm, urothelial carcinoma, breast cancer, urogenital neoplasm

Acts on a complex — shared with TUBB4B, TUBB1, TUBA4A +11 more · 1 of 15 recorded protein targets — broad pharmacology

cabazitaxel
ApprovedInhibitor

Tubulin inhibitor

Appears in clinical studies involving prostate cancer, breast cancer, prostate neoplasm, neoplasm

Acts on a complex — shared with TUBB4B, TUBB1, TUBA4A +11 more · 1 of 15 recorded protein targets — broad pharmacology

ChEMBL mechanism, action type and target identity. Open Targets clinical status and indications.

Translational evidence

Open Targets 26

Why this target matters therapeutically — disease associations, drugs in development, tractability and safety, from Open Targets.

Strongest genetic associations

Human genetic evidence — the most direct causal link between this target and a disease.

complex cortical dysplasia with other brain malformations 10.93

Genetic · overall 0.75

fibrosis of extraocular muscles, congenital, 3A, with or without extraocular involvement0.92

Genetic · overall 0.80

Cortical dysgenesis with pontocerebellar hypoplasia due to TUBB3 mutation0.85

Genetic literature · overall 0.75

congenital fibrosis of the extraocular muscles0.81

Genetic literature · overall 0.66

neoplasm0.16

Genetic · overall 0.62

Highest-confidence therapeutic associations

Diseases where a drug acting on this target has already reached clinical development.

non-small cell lung carcinoma0.99

Clinical · overall 0.62

breast cancer0.99

Clinical · overall 0.63

breast carcinoma0.98

Clinical · overall 0.62

prostate cancer0.97

Clinical · overall 0.62

Hodgkins lymphoma0.97

Clinical · overall 0.59

Show all associations
fibrosis of extraocular muscles, congenital, 3A, with or without extraocular involvement0.80
Cortical dysgenesis with pontocerebellar hypoplasia due to TUBB3 mutation0.75
complex cortical dysplasia with other brain malformations 10.75
congenital fibrosis of the extraocular muscles0.66
breast cancer0.63
neoplasm0.62
prostate cancer0.62
non-small cell lung carcinoma0.62
breast carcinoma0.62
Hodgkins lymphoma0.59

Open Targets ranks 1,073 associations for this target and we store the top 10 by aggregated score. The long tail is largely literature co-mention and RNA-expression evidence, not evidence that this target drives those diseases.

Known drugs · 88 total

BIIB-015Phase 1

neoplasm

PLINABULINPhase 3

non-small cell lung carcinoma · non-small cell lung carcinoma · non-small cell squamous lung carcinoma

CROLIBULINPhase 1 2

thyroid cancer · lymphoma

VERUBULINPhase 2

glioblastoma · melanoma

RG-7598Phase 1

plasma cell myeloma

ANETUMAB RAVTANSINEPhase 2

malignant pleural mesothelioma · mesothelioma · lung adenocarcinoma

SAR-566658Phase 2

triple-negative breast carcinoma · breast cancer

DENINTUZUMAB MAFODOTINPhase 2

diffuse large B-cell lymphoma · follicular lymphoma · diffuse large B-cell lymphoma

AZINTUXIZUMAB VEDOTINPhase 1

plasma cell myeloma

TELISOTUZUMAB VEDOTINPhase 3

non-small cell lung carcinoma · non-small cell lung carcinoma · squamous cell lung carcinoma

Tractability

SM · Approved DrugSM · Structure with LigandSM · High-Quality LigandSM · Druggable FamilyPR · Database UbiquitinationPR · Half-life DataPR · Small Molecule BinderOC · Approved Drug

Clinical trials

30

Trials of drugs that target this protein — reached indirectly through those drugs, so a trial listed here studies the drug, not the protein.

A Phase III Randomized Open-Label Study of Single Agent Pembrolizumab vs Physicians' Choice of Single Agent Docetaxel, Paclitaxel, or Irinotecan in Subjects With Advanced/Metastatic Adenocarcinoma and Squamous Cell Carcinoma of the Esophagus That Have Progressed After First-Line Standard Therapy (KEYNOTE-181)PHASE3

COMPLETED · via Paclitaxel · NCT02564263

Differential Gene Regulation During Neoadjuvant Therapy Trial of Epirubicin/Cyclophosphamide (EC) vs Docetaxel/Capecitabine (DX) Regimens in Patients With Large ER-positive and ER-negative Breast Cancers: A Randomized Phase II Trial.PHASE2

COMPLETED · via docetaxel · NCT01869192

Adjuvant Lung Cancer Enrichment Marker Identification and Sequencing Trial (ALCHEMIST)NA

ACTIVE_NOT_RECRUITING · via Paclitaxel · NCT02194738

A Phase Ib Dose Escalation Study of MK-4827 in Combination With Carboplatin, Carboplatin/Paclitaxel and Carboplatin/Liposomal Doxorubicin in Patients With Advanced Solid TumorsPHASE1

TERMINATED · via Paclitaxel · NCT01110603

Colchicine for Patients With Aortic Stenosis Undergoing Transcatheter Aortic Valve Replacement (Co-STAR): a Randomized-controlled TrialPHASE3

COMPLETED · via Colchicine · NCT04870424

SUNRISE: A Phase III, Randomized, Double-Blind, Placebo-Controlled Multicenter Trial of Bavituximab Plus Docetaxel Versus Docetaxel Alone in Patients With Previously Treated Stage IIIb/IV Non-Squamous Non Small-Cell Lung CancerPHASE3

COMPLETED · via docetaxel · NCT01999673

Show remaining trials (24)
Phase II Study of Docetaxel and Thalidomide as a Second-Line Treatment for Non-Small Cell Lung CancerPHASE2

COMPLETED · via docetaxel · NCT00114192

A Phase II Study of Gemzar, Taxotere, and Xeloda (GTX) for Adjuvant Pancreatic CancerPHASE2

COMPLETED · via docetaxel · NCT00882310

A Phase I Study of Paclitaxel, Carboplatin, and Increasing Doses of Doxil in Untreated Ovarian, Peritoneal, and Tubal CarcinomaPHASE1

COMPLETED · via Paclitaxel · NCT00003385

Phase 3 Study of Pembrolizumab in Combination With Carboplatin/Taxane (Paclitaxel or Nab-paclitaxel) Followed by Pembrolizumab With or Without Maintenance MK-2870 in the First-line Treatment of Metastatic Squamous Non-small Cell Lung CancerPHASE3

RECRUITING · via Paclitaxel · NCT06422143

Randomized Phase III Trial Comparing an Association of Hormonal Treatment and Docetaxel Versus the Hormonal Treatment Alone in Metastatic Prostate CancersPHASE3

COMPLETED · via docetaxel · NCT00104715

A Phase II Study of Taxotere and Irinotecan (CPT-11) in Patients With Advanced Adenocarcinoma of the Lower Esophagus, Esophagogastric Junction, and Gastric CardiaPHASE2

COMPLETED · via docetaxel · NCT00004235

A Multicentre, Phase Ib/II Clinical Study of AK109 and AK104 With or Without Chemotherapy in Second-line Treatment of Advanced Gastric Adenocarcinoma or Gastroesophageal Junction AdenocarcinomaPHASE1/PHASE2

RECRUITING · via Paclitaxel · NCT04982276

A Phase I Pharmacokinetic, Pharmacodynamic, and Clinical Study of the Combination of the Angiogenesis Inhibitor SU5416 and Paclitaxel in Recurrent or Metastatic Carcinoma of the Head and NeckPHASE1

COMPLETED · via Paclitaxel · NCT00005647

A Phase II Study of Sequential Paclitaxel and Bryostatin-1 for Patients With Advanced Pancreatic CancerPHASE2

COMPLETED · via Paclitaxel · NCT00031694

Phase II Trial of Pevonedistat (TAK-924) Plus Docetaxel in Patients With Previously Treated Advanced Non-Small Cell Lung CancerPHASE2

TERMINATED · via docetaxel · NCT03228186

A Phase II Trial of External Irradiation (50.4 GY) and Weekly Paclitaxel (Taxol) for Non-Metastatic, Unresectable Pancreatic CancerPHASE2

COMPLETED · via Paclitaxel · NCT00003591

Synergy of Pembrolizumab Anti-PD-1 Immunotherapy With Chemotherapy for Poorly Chemo-responsive Thyroid and Salivary Gland Tumors. The iPRIME Study.PHASE2

ACTIVE_NOT_RECRUITING · via docetaxel · NCT03360890

An Exploratory Pilot Study of Nab-paclitaxel Based Induction Chemotherapy Followed by Response-Stratified Locoregional Therapy for Patients With Stage III and IV HPV-Related Oropharyngeal Cancer - the OPTIMA HPV TrialPHASE2

COMPLETED · via Paclitaxel · NCT02258659

A Randomized, Placebo-Controlled, Double-Blind Phase 3 Study to Evaluate the Efficacy and Safety of Tislelizumab (BGB-A317) in Combination With Chemotherapy as First-Line Treatment in Patients With Unresectable, Locally Advanced Recurrent or Metastatic Esophageal Squamous Cell CarcinomaPHASE3

COMPLETED · via Paclitaxel · NCT03783442

Randomized Phase II 2 x 2 Factorial Trial of the Addition of Carboplatin +/- Bevacizumab to Neoadjuvant Weekly Paclitaxel Followed by Dose-Dense AC in Hormone Receptor-Poor/HER2-Negative Resectable Breast CancerPHASE2

COMPLETED · via Paclitaxel · NCT00861705

Biochemical Recurrence Rate of Radical Prostatectomy Combined With Neoadjuvant and Adjuvant in Patients With High Risk Locallized Prostate CancerNA

UNKNOWN · via docetaxel · NCT01530295

Phase I Study of Radiation Dose Intensification With Accelerated Hypofractionated Intensity Modulated Radiation Therapy and Concurrent Carboplatin and Paclitaxel for Inoperable Esophageal CancerPHASE1

ACTIVE_NOT_RECRUITING · via Paclitaxel · NCT04046575

RC48-ADC in Combination With Envolizumab for the First-line Treatment of Locally Advanced or Metastatic Biliary Tract Cancer With Positive HER-2: A Prospective, Single-arm Phase II Trial.PHASE2

UNKNOWN · via disitamab vedotin · NCT05417230

An Open, Single Arm, Phase II Clinical Study on the Efficacy and Safety of Bladder Sparing Therapy With Vidixizumab Combined With Local Radiotherapy in Patients With HER-2 Expressing Myometrial Invasive Urothelium CarcinomaPHASE2

UNKNOWN · via disitamab vedotin · NCT05912205

A Randomized, Multicenter, Open-label Clinical Study Using Peripheral Blood Circulating Tumor DNA to Evaluate the Efficacy of Preoperative Treatment With Pyrotinib + Trastuzumab + Docetaxel Versus Pertuzumab + Trastuzumab + Docetaxel in Early or Locally Advanced HER2-positive Breast CancerPHASE2

RECRUITING · via docetaxel · NCT07335081

A Phase 2, Single Arm Study of Mirvetuximab Soravtansine in Recurrent Platinum-Sensitive, High-Grade Epithelial Ovarian, Primary Peritoneal, or Fallopian Tube Cancers With High Folate Receptor-Alpha ExpressionPHASE2

COMPLETED · via mirvetuximab soravtansine · NCT05041257

A Phase II, Multi-Center Study to Evaluate the Efficacy and Safety of Volrustomig as Monotherapy or in Combination With Anti-cancer Agents in Participants With Advanced/Metastatic Solid TumorsPHASE2

RECRUITING · via Paclitaxel · NCT06535607

A Phase 1, Three-Part, Open-Label, Parallel-Cohort Safety and Tolerability Study of Relugolix in Combination With Abiraterone Acetate Plus a Corticosteroid, Apalutamide, or Docetaxel With or Without Prednisone in Men With Metastatic Castration-Sensitive Prostate Cancer or Non-Metastatic or Metastatic Castration-Resistant Prostate CancerPHASE1

COMPLETED · via docetaxel · NCT04666129

Assessing REsponse to Neoadjuvant Taxotere and Trastuzumab in Nigerian Women With HER2-positive Breast Cancer (ARETTA)PHASE2

ACTIVE_NOT_RECRUITING · via docetaxel · NCT03879577

ClinicalTrials.gov via the drug-target graph.

Forefront confidence

Synthesis

Our own weighting of the evidence behind each disease association. Human genetics and clinical evidence count for most; literature co-mention counts for little, because two entities sharing an abstract is not evidence that one drives the other.

complex cortical dysplasia with other brain malformations 1Well supported
0.94
agreement 0.82–1.00
Genetic84%Animal model16%Literature1%Genetic literaturedup

Open Targets aggregate 0.75 · 3 independent evidence families · 1 not counted as duplicate

fibrosis of extraocular muscles, congenital, 3A, with or without extraocular involvementWell supported
0.93
agreement 0.81–1.00
Genetic87%Animal model13%Literature1%Genetic literaturedup

Open Targets aggregate 0.80 · 3 independent evidence families · 1 not counted as duplicate

Cortical dysgenesis with pontocerebellar hypoplasia due to TUBB3 mutationWell supported
0.85
agreement 0.73–0.97
Genetic82%Animal model18%Literature0%Genetic literaturedup

Open Targets aggregate 0.75 · 3 independent evidence families · 1 not counted as duplicate

neoplasmWell supported
0.80
agreement 0.69–0.91
Clinical72%Genetic16%Literature12%

Open Targets aggregate 0.62 · 3 independent evidence families

non-small cell lung carcinomaWell supported
0.78
agreement 0.64–0.91
Clinical86%Literature8%RNA expression6%

Open Targets aggregate 0.62 · 3 independent evidence families

This ranking differs from Open Targets' own: re-weighting moves genetically-evidenced diseases above more heavily co-mentioned ones. The evidence agreement range shows how closely the independent evidence families agree — it is not a statistical confidence interval, and nothing here is fitted to outcome data. Derived from Open Targets evidence types under Forefront weighting; the underlying per-type scores are shown above so the calculation can be checked.

What's happening now

60

Recent activity around this target, drawn from one canonical event stream. Every item is reached through 10 drugs that target this protein, so each event is news about that drug rather than about the protein directly.

  1. Trial results posted2026-07-27

    Cemiplimab in High-risk or Locally Advanced Luminal and Triple Negative Breast Cancer (CemiHALT )

    Results posted · ClinicalTrials.gov · via Paclitaxel

  2. Trial status changed2026-07-24

    Phase II Study Of Combination Ruxolitinib (INCB018424) With Preoperative Chemotherapy For Triple Negative Inflammatory Breast Cancer

    Status changed to Completed · ClinicalTrials.gov · via Paclitaxel

  3. Trial results posted2026-07-20

    A Phase 3, Randomized Study to Evaluate the Efficacy and Safety of Pembrolizumab (MK-3475) + Lenvatinib (E7080/MK-7902) + Chemotherapy Compared With Standard of Care as First-line Intervention in Participants With Metastatic Esophageal Carcinoma.

    Results posted · ClinicalTrials.gov · via Paclitaxel

  4. Trial status changed2026-07-20

    A Phase 3, Randomized Study to Evaluate the Efficacy and Safety of Pembrolizumab (MK-3475) + Lenvatinib (E7080/MK-7902) + Chemotherapy Compared With Standard of Care as First-line Intervention in Participants With Metastatic Esophageal Carcinoma.

    Status changed to Completed · ClinicalTrials.gov · via Paclitaxel

  5. Trial status changed2026-07-17

    A Phase 1b Open-Label Study to Evaluate the Safety and Anti-cancer Activity of Loncastuximab Tesirine in Combination With Other Anti-cancer Agents in Patients With Relapsed or Refractory B-cell Non-Hodgkin Lymphoma (LOTIS-7)

    Status changed to Active, not recruiting · ClinicalTrials.gov · via polatuzumab vedotin

  6. Indication expanded2026-07-10

    Indication expansion: ENFORTUMAB VEDOTIN (BLA761137)

    fda · regulatory · fda · via enfortumab vedotin

  7. CHMP positive opinion2026-05-22

    CHMP positive opinion: Colchicine Agepha Pharma (EMA)

    ema · regulatory · ema · via Colchicine

  8. Indication expanded2025-11-21

    Indication expansion: ENFORTUMAB VEDOTIN (BLA761137)

    fda · regulatory · fda · via enfortumab vedotin

  9. Regulatory approval2025-07-23

    Approval: Blenrep (EMA)

    ema · regulatory · ema · via belantamab mafodotin

  10. Regulatory approval2025-03-28

    Approval: Tivdak (EMA)

    ema · regulatory · ema · via tisotumab vedotin

  11. New publication2025-03-05
    Pembrolizumab Plus Docetaxel Versus Docetaxel for Previously Treated Metastatic Castration-Resistant Prostate Cancer: The Randomized, Double-Blind, Phase III KEYNOTE-921 Trial.

    Journal of clinical oncology : official journal of the American Society of Clinical Oncology · 2025 · 43 citations · Europe PMC · via docetaxel

  12. Label change2025-02-27

    Label change: ENFORTUMAB VEDOTIN (BLA761137)

    fda · regulatory · fda · via enfortumab vedotin

Objective event titles are shown unmodified; the event kind and significance line are derived from structured fields. Forefront AttentionEvent stream aggregating Europe PMC Regulatory filings ClinicalTrials.gov.