A Phase 1/2 interventional study of Pirtobrutinib and Placebo in Immune Thrombocytopenia (ITP), sponsored by Eli Lilly and Company. Recruiting at 43 sites in 10 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-11-04.
Sponsored by Eli Lilly and Company · Phase 1/2, Interventional, and Basic science
The purpose of the phase 1 part of this study was to evaluate how well pirtobrutinib is tolerated and what side effects may occur. The phase 2 part of the study will further investigate efficacy and safety of multiple pirtobrutinib dosages versus placebo.
The study drug will be administered orally in participants with Primary Immune Thrombocytopenia (ITP). Blood tests will be performed to check how much pirtobrutinib gets into the bloodstream and how long it takes the body to eliminate it.
The study will last up to approximately 16 weeks for phase 1 dose-escalation and 28 weeks for phase 2 dose-optimization, excluding screening.
503 studies on the registry are indexed under Purpura, Thrombocytopenic, Idiopathic; 158 are open to participants now.
This study's planned enrollment of 68 is above the median of 58 across 376 interventional studies indexed under Purpura, Thrombocytopenic, Idiopathic.
Browse Purpura, Thrombocytopenic, Idiopathic studies →Eli Lilly and Company is the lead sponsor of 2,106 studies on the registry; 152 are open to participants now.
Of its 536 completed or terminated interventional studies of FDA-regulated products, 357 (67%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
A line of therapy is one course of treatment, which may combine several drugs. First-line is the first course given; second-line follows when that stops working or is not tolerated.
“Two prior lines” means two courses that count separately under the study’s rules — not simply two drugs. Ask the study team if you are unsure how yours are counted.
Relapsed: the illness came back after treatment had worked. Refractory: it did not respond to treatment, or stopped responding while still on it.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Platelets
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Line of therapy
A line of therapy is one course of treatment, which may combine several drugs. First-line is the first course given; second-line follows when that stops working or is not tolerated.
“Two prior lines” means two courses that count separately under the study’s rules — not simply two drugs. Ask the study team if you are unsure how yours are counted.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Relapsed and refractory
Relapsed: the illness came back after treatment had worked. Refractory: it did not respond to treatment, or stopped responding while still on it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis C tests
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Pirtobrutinib administered orally
Drug: Pirtobrutinib
Pirtobrutinib administered orally
Drug: Pirtobrutinib
Placebo administered orally
Drug: Placebo
Administered orally
Administered orally
Phase 1-Number of Participants with One or More Treatment Emergent Adverse Events (TEAEs) and Serious Adverse Event(s) (SAEs) Considered by the Investigator to be Related to Study Drug Administration
A summary of TEAEs and SAEs regardless of causality, will be reported in the Reported Adverse Events module
Time frame: Baseline Up to Week 4
Phase 1-Dose Limiting Toxicity (DLT) of Pirtobrutinib
DLTs of Pirtobrutinib
Time frame: Baseline Up to Week 4
Phase 1-Number of Participants with Treatment-Related Adverse Events as Assessed by Vital Signs: Blood Pressure, Pulse Rate, and Body Temperature
Blood Pressure, Pulse Rate, and Body Temperature
Time frame: Baseline Up to Week 16
Phase 1-Number of Participants with Treatment-Related Adverse Events as Assessed by Clinical Lab Tests: Hematology, Clinical Chemistry, Urinalysis, Pregnancy, Hepatitis Serology and Cytomegalovirus (CMV)
Hematology, Clinical Chemistry, Urinalysis, Pregnancy, Hepatitis Serology and Cytomegalovirus (CMV)
Time frame: Baseline Up to Week 16
Phase 1-Number of Participants with Treatment-Related Adverse Events as Assessed by Electrocardiograms (ECGs): ECG QT Interval
ECG QT Interval
Time frame: Baseline Up to Week 16
Phase 2-Efficacy of Pirtobrutinib Versus Placebo
Stable platelet response rate is defined as the proportion of participants achieving platelet count of greater than or equal to 50 thousand per microliter (k/μL) and on at least 4 of the 6 consecutive biweekly visits between weeks 14 and 24 in the absence of rescue therapy and prohibited concomitant medication that may impact efficacy
Time frame: Baseline Up to Week 24
Phase 1-Preliminary Efficacy of Pirtobrutinib
Platelet response rate defined as proportion of participants who achieve at least 2 consecutive platelet counts of greater than or equal to 50 k/μL and an increase from baseline of greater than or equal to 20 k/μL to any time during treatment without the use of rescue medication within 4 weeks prior to the latest elevated platelet count.
Time frame: Day 1 Up to Week 12
Phase 1-Evaluate the Extent of Disease Control
Number of cumulative weeks with platelet counts greater than or equal to 50 k/μL by Week 12
Time frame: Day 1 Up to Week 12
Phase 1: Pharmacokinetics (PK) of Pirtobrutinib
PK: Plasma Concentrations of Pirtobrutinib
Time frame: Baseline Up to Week 16
Phase 2-Assess Additional Efficacy of Pirtobrutinib Versus Placebo
Platelet response rate is defined as the proportion of participants with greater than or equal to 2 consecutive platelet counts greater than or equal to 50 k/μL and an increase of platelet count of greater than or equal to 20 k/μL from baseline to any time during treatment or follow-up without the use of rescue medication or prohibited concomitant medication that may impact efficacy within 4 weeks prior to the latest elevated platelet count
Time frame: Week 14 Up to Week 24
Phase 2-Evaluate the Extent of Disease Control of Pirtobrutinib Versus Placebo
Number of cumulative weeks with platelet counts greater than or equal to 50 k/μL
Time frame: Baseline Up to Week 24
Phase 2-Evalulate the Extent of Disease Control of Pirtobrutinib Versus Placebo
Number of cumulative weeks with platelet counts greater than or equal to 100 k/μL
Time frame: Baseline Up to Week 24
Phase 2-Describe the Use of Rescue Medications of Pirtobrutinib Versus Placebo
Proportion of participants requiring rescue therapy
Time frame: Baseline Up to Week 24
Phase 2-Describe the PK of Pirtobrutinib
PK: Plasma Concentrations of Pirtobrutinib
Time frame: Week 16 Up to Week 40
Plan to share: No
Started Jul 2025 (actual). Primary completion is estimated for Feb 2028, 31 months after the start.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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Studies of the drug tested here: Pirtobrutinib
Purpura, Thrombocytopenic, Idiopathic →