A Phase 2 interventional study of Tremelimumab and Placebo in Unresectable Pleural or Peritoneal Malignant Mesothelioma, sponsored by MedImmune LLC. Active, not recruiting at 104 sites in 19 countries. Open to participants aged 18 Years to 99 Years. Per ClinicalTrials.gov, last updated 2026-07-27.
Sponsored by MedImmune LLC (part of AstraZeneca) · Phase 2, Interventional, and Treatment
This is a Phase 2b, randomized, double-blind, parallel-group study. Subjects with unresectable pleural or peritoneal malignant mesothelioma will be randomized in a 2:1 ratio to receive either tremelimumab or placebo. Approximately 564 subjects will be enrolled at study centers in multiple countries. The study consists of a screening period, a treatment period, a 90-day follow-up period for safety, and a long-term survival follow-up period.
This is a Phase 2b, randomized, double-blind, parallel-group study. Subjects with unresectable pleural or peritoneal malignant mesothelioma will be randomized in a 2:1 ratio to receive either tremelimumab or placebo.
Randomization will be stratified by EORTC status (low-risk vs high-risk), line of therapy (second vs third), and anatomical site (pleural vs peritoneal). This study plans to use the EORTC to stratify subjects into high or low risk groups in order to ensure balanced randomization to the different treatment groups. For subjects in whom pemetrexed was contraindicated or not tolerated or not an approved therapy (eg, peritoneal mesothelioma), prior therapy with a first-line platinum-based regimen is required. Approximately 564 subjects will be enrolled at study centers in multiple countries.
The study consists of a screening period, a treatment period, a 90-day follow-up period for safety, and a long-term survival follow-up period.
339 studies on the registry are indexed under Mesothelioma, Malignant; 64 are open to participants now.
This study's enrollment of 571 is above the median of 39 across 271 interventional studies indexed under Mesothelioma, Malignant.
Browse Mesothelioma, Malignant studies →MedImmune LLC is the lead sponsor of 270 studies on the registry; none are open to participants now.
Of its 52 completed or terminated interventional studies of FDA-regulated products, 29 (56%) have results posted.
First submitted after MedImmune LLC became part of AstraZeneca.
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.
The diagnosis was confirmed by looking at a sample under a microscope: tissue from a biopsy or surgery (histology), or cells from a fluid or needle sample (cytology).
Your pathology report is the document that shows this.
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
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.
The US National Cancer Institute’s scale of how severe an adverse event is — any unwanted medical event during a study, such as a symptom, an illness or an abnormal test result, whether or not a treatment caused it. Whether it did is judged separately.
“Side effects of earlier treatment resolved to grade 1 or less” means they have settled to mild or gone.
The standard rules for measuring tumours on CT or MRI scans, to tell whether a cancer is shrinking, stable or growing during treatment.
“Measurable disease per RECIST 1.1” usually means at least one tumour 10 mm or more at its longest on a CT scan, or a lymph node 15 mm or more across its short axis.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after 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.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
PD-1, PD-L1 and CTLA-4 are proteins that act as brakes on the immune system. Checkpoint inhibitors, such as pembrolizumab or nivolumab, block them so the immune system can attack a cancer.
PD-L1 can also be measured in a tumour sample. Some scores count stained tumour cells only (TPS); others also count certain immune cells (CPS). The study names the score and the minimum it uses.
A condition in which the immune system attacks the body’s own tissues, such as rheumatoid arthritis, lupus, psoriasis, type 1 diabetes or inflammatory bowel disease.
Immunotherapy studies often leave out active autoimmune disease, and some name exceptions, such as thyroid disease on replacement hormone. Check the exceptions this study lists.
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
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.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Vaccines made with a weakened form of the germ, such as measles–mumps–rubella (MMR), chickenpox and yellow fever. They can be risky when the immune system is weakened. Flu injections are not live; the nasal flu spray is.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Histologically or cytologically confirmed
The diagnosis was confirmed by looking at a sample under a microscope: tissue from a biopsy or surgery (histology), or cells from a fluid or needle sample (cytology).
Your pathology report is the document that shows this.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECOG performance status
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
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.
CTCAE grade
The US National Cancer Institute’s scale of how severe an adverse event is — any unwanted medical event during a study, such as a symptom, an illness or an abnormal test result, whether or not a treatment caused it. Whether it did is judged separately.
“Side effects of earlier treatment resolved to grade 1 or less” means they have settled to mild or gone.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
RECIST
The standard rules for measuring tumours on CT or MRI scans, to tell whether a cancer is shrinking, stable or growing during treatment.
“Measurable disease per RECIST 1.1” usually means at least one tumour 10 mm or more at its longest on a CT scan, or a lymph node 15 mm or more across its short axis.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after 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.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
PD-1, PD-L1 and checkpoint inhibitors
PD-1, PD-L1 and CTLA-4 are proteins that act as brakes on the immune system. Checkpoint inhibitors, such as pembrolizumab or nivolumab, block them so the immune system can attack a cancer.
PD-L1 can also be measured in a tumour sample. Some scores count stained tumour cells only (TPS); others also count certain immune cells (CPS). The study names the score and the minimum it uses.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Autoimmune disease
A condition in which the immune system attacks the body’s own tissues, such as rheumatoid arthritis, lupus, psoriasis, type 1 diabetes or inflammatory bowel disease.
Immunotherapy studies often leave out active autoimmune disease, and some name exceptions, such as thyroid disease on replacement hormone. Check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Metastases
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
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.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Immunosuppression
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Live vaccines
Vaccines made with a weakened form of the germ, such as measles–mumps–rubella (MMR), chickenpox and yellow fever. They can be risky when the immune system is weakened. Flu injections are not live; the nasal flu spray is.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Tremelimumab
Drug: Tremelimumab
Placebo
Drug: Placebo
Tremelimumab is to be administered as an IV solution, followed by observation.
Placebo is to be administered as an IV solution, followed by observation.
Overall Survival (OS)
Overall survival (OS) by treatment arm
Time frame: 3 years.
OS Rate at 18 Months by Treatment Arm
The percentage of patients still alive at 18 months
Time frame: 18 months
Progression-free Survival by Treatment Arm
Progression-free survival will be measured from randomization to the first documentation of disease progression or death due to any cause, whichever occurs first. Progression is defined using the modified Response Evaluation Criteria in Solid Tumours (RECIST) for pleural mesothelioma or RECIST v1.1 for peritoneal mesothelioma and assessed by computed tomography (CT) or magnetic resonance imaging (MRI), as a 20% increase in the sum of the longest diameter of target lesions, or a measurable increase in a non-target lesion, or the appearance of new lesions.
Time frame: Time from randomization to disease progression or death, whichever occurs first, assessed up to 3 years.
Overall Response Rate by Treatment Arm
Overall response rate is defined as the proportion of participants with confirmed CR or PR per the modified Response Evaluation Criteria in Solid Tumours (RECIST) for pleural mesothelioma or RECIST v1.1 for peritoneal mesothelioma and assessed by computed tomography (CT) or magnetic resonance imaging (MRI). Complete Response (CR) corresponds to disappearance of all target lesions, and Partial Response (PR), \>=30% decrease in the sum of the longest diameter of target lesions. Overall Response (OR) = CR + PR.
Time frame: Time from randomization to best response to treatment, assessed up to 3 years.
Duration of Response by Treatment Arm
Duration of response will be defined as the duration from the first documentation of complete response (CR), partial response (PR) to the first documented disease progression.
Time frame: Duration of response from the first documentation of objcetive response (confirmed CR or PR) to the first documented disease progression, assessed up to 14 weeks after the initial response.
Disease Control Rate by Treatment Arm
Disease control rate (DCR) is defined as the proportion of participants with best response of complete response (CR), partial response (PR), or stable disease (SD) of ≥ 12 weeks duration
Time frame: Time from randomization to disease progression or death, whichever occurs first, assessed up to 3 years.
Durable Disease Control Rate by Treatment Arm
Durable disease control rate (DDCR) is defined as the percentage of participants with best response of complete response (CR), partial response (PR), or stable disease (SD) of ≥ 6 months duration
Time frame: Time from randomization to disease progression or death, whichever occurs first, assessed up to 3 years.
Number of Participants Reporting Any Adverse Event
Any untoward medical occurrence in a patient or clinical investigation participants administered a pharmaceutical product and which does not necessarily have a causal relationship with this treatment.
Time frame: Day 1- 90 days post dose
Number of Participants Reporting Any Serious Adverse Events
Time frame: Day 1 to 90 days post dose
Number of Participants With Positive Anti-drug Antibodies
The immunogenicity titer is reported for samples confirmed positive for the presence of anti tremelimumab antibodies.
Time frame: Week 5
| Milestone | PLACEBO | TREMELIMUMAB |
|---|---|---|
| Started | 189 | 382 |
| Randomized | 189 | 382 |
| Completed | 0 | 3 |
| Not completed | 189 | 379 |
| Withdrew: Death | 155 | 313 |
| Withdrew: Withdrawal by subject | 14 | 20 |
| Withdrew: Withdrawing due to other reason | 20 | 46 |
Overall survival (OS) by treatment arm
| Number of Participants | PLACEBO | TREMELIMUMAB |
|---|---|---|
| Number of patients with Events (Death) | 154 | 307 |
| Number patients censored <= 2 weeks before DCO | 25 | 58 |
| Number of patients censored > 2 weeks before DCO | 10 | 17 |
The percentage of patients still alive at 18 months
| Percentage of Participants | TREMELIMUMAB | PLACEBO |
|---|---|---|
| OS Rate at 18 Months by Treatment Arm | 17.4 (13.4 to 21.8) | 18.2 (12.7 to 24.5) |
Progression-free survival will be measured from randomization to the first documentation of disease progression or death due to any cause, whichever occurs first. Progression is defined using the modified Response Evaluation Criteria in Solid Tumours (RECIST) for pleural mesothelioma or RECIST v1.1 for peritoneal mesothelioma and assessed by computed tomography (CT) or magnetic resonance imaging (MRI), as a 20% increase in the sum of the longest diameter of target lesions, or a measurable increase in a non-target lesion, or the appearance of new lesions.
| Months | TREMELIMUMAB | PLACEBO |
|---|---|---|
| Progression-free Survival by Treatment Arm | 2.69 (2.66 to 2.76) | 2.76 (2.76 to 2.79) |
Overall response rate is defined as the proportion of participants with confirmed CR or PR per the modified Response Evaluation Criteria in Solid Tumours (RECIST) for pleural mesothelioma or RECIST v1.1 for peritoneal mesothelioma and assessed by computed tomography (CT) or magnetic resonance imaging (MRI). Complete Response (CR) corresponds to disappearance of all target lesions, and Partial Response (PR), \>=30% decrease in the sum of the longest diameter of target lesions. Overall Response (OR) = CR + PR.
| Percentage | TREMELIMUMAB | PLACEBO |
|---|---|---|
| Overall Response Rate by Treatment Arm | 4.5 (2.6 to 7.0) | 1.1 (0.1 to 3.8) |
Duration of response will be defined as the duration from the first documentation of complete response (CR), partial response (PR) to the first documented disease progression.
| Months | TREMELIMUMAB | PLACEBO |
|---|---|---|
| Duration of Response by Treatment Arm | 4.8 (0 to 13.4) | 5.57 (2.8 to 8.3) |
Disease control rate (DCR) is defined as the proportion of participants with best response of complete response (CR), partial response (PR), or stable disease (SD) of ≥ 12 weeks duration
| Percentage | TREMELIMUMAB | PLACEBO |
|---|---|---|
| Disease Control Rate by Treatment Arm | 21.7 (16.0 to 28.3) | 27.7 (23.3 to 32.5) |
Durable disease control rate (DDCR) is defined as the percentage of participants with best response of complete response (CR), partial response (PR), or stable disease (SD) of ≥ 6 months duration
| Percentage | TREMELIMUMAB | PLACEBO |
|---|---|---|
| Durable Disease Control Rate by Treatment Arm | 16.8 (13.1 to 20.9) | 11.6 (7.4 to 17.1) |
Any untoward medical occurrence in a patient or clinical investigation participants administered a pharmaceutical product and which does not necessarily have a causal relationship with this treatment.
| Participants | TREMELIMUMAB | PLACEBO |
|---|---|---|
| Number of Participants Reporting Any Adverse Event | 364 | 179 |
| Participants | PLACEBO | TREMELIMUMAB |
|---|---|---|
| Number of Participants Reporting Any Serious Adverse Events | 85 | 218 |
The immunogenicity titer is reported for samples confirmed positive for the presence of anti tremelimumab antibodies.
| Participants | PLACEBO | TREMELIMUMAB |
|---|---|---|
| Number of Participants With Positive Anti-drug Antibodies | 0 | 15 |
Non-serious events are listed at a 5% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| PLACEBO | 160/189 (84.7%) | 85/189 (45%) | 159/189 (84.1%) |
| TREMELIMUMAB | 318/382 (83.2%) | 218/380 (57.4%) | 338/380 (88.9%) |
| Event | PLACEBO | TREMELIMUMAB |
|---|---|---|
| DiarrhoeaGastrointestinal disorders | 1/189 | 69/380 |
| DyspnoeaRespiratory, thoracic and mediastinal disorders | 24/189 | 29/380 |
| ColitisGastrointestinal disorders | 0/189 | 24/380 |
| VomitingGastrointestinal disorders | 7/189 | 12/380 |
| Pericardial effusionCardiac disorders | 6/189 | 9/380 |
| AscitesGastrointestinal disorders | 6/189 | 3/380 |
| PneumoniaInfections and infestations | 6/189 | 11/380 |
| Pleural effusionRespiratory, thoracic and mediastinal disorders | 6/189 | 6/380 |
| PyrexiaGeneral disorders | 0/189 | 11/380 |
| DehydrationMetabolism and nutrition disorders | 1/189 | 10/380 |
| Event | PLACEBO | TREMELIMUMAB |
|---|---|---|
| DiarrhoeaGastrointestinal disorders | 35/189 | 168/380 |
| FatigueGeneral disorders | 60/189 | 91/380 |
| DyspnoeaRespiratory, thoracic and mediastinal disorders | 60/189 | 103/380 |
| Decreased appetiteMetabolism and nutrition disorders | 45/189 | 110/380 |
| ConstipationGastrointestinal disorders | 53/189 | 65/380 |
| NauseaGastrointestinal disorders | 38/189 | 103/380 |
| PruritusSkin and subcutaneous tissue disorders | 15/189 | 103/380 |
| RashSkin and subcutaneous tissue disorders | 14/189 | 76/380 |
| VomitingGastrointestinal disorders | 16/189 | 71/380 |
| Musculoskeletal chest painMusculoskeletal and connective tissue disorders | 33/189 | 47/380 |
| Age, Continuous(Years) | TREMELIMUMAB | PLACEBO | Total |
|---|---|---|---|
| Mean | 65.2 ± 9.24 | 66.3 ± 8.8 | 65.6 ± 9.10 |
| Age, Customized(Participants) | TREMELIMUMAB | PLACEBO | Total |
|---|---|---|---|
| < 65 years | 162 | 75 | 237 |
| >= 65 years | 220 | 114 | 334 |
| Sex: Female, Male(Participants) | TREMELIMUMAB | PLACEBO | Total |
|---|---|---|---|
| Female | 99 | 38 | 137 |
| Male | 283 | 151 | 434 |
Showing the first 100 of 104 sites across 19 countries. Choose a country and city above to see the rest.
Plan to share: Yes — Qualified researchers can request access to anonymized individual patient-level data from AstraZeneca group of companies sponsored clinical trials via the request portal. All request will be evaluated as per the AZ disclosure commitment: https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure
Supporting information: Study protocol, Statistical analysis plan
Time frame: AstraZeneca will meet or exceed data availability as per the commitments made to the EFPIA Pharma Data Sharing Principles. For details of our timelines, please rerefer to our disclosure commitment at https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure
Access criteria: When a request has been approved AstraZeneca will provide access to the de-identified individual patient-level data in an approved sponsored tool . Signed Data Sharing Agreement (non-negotiable contract for data accessors) must be in place before accessing requested information. Additionally, all users will need to accept the terms and conditions of the SAS MSE to gain access. For additional details, please review the Disclosure Statements at https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure
Data sharing details ↗ · astrazenecagroup-dt.pharmacm.com
Ran from May 2013 to primary completion in Jan 2016, 32 months.
Results were first posted in Aug 2017, 1 year 6 months after primary completion. A results delay was requested in Jan 2017.
Of 48 phase 2 interventional studies under Mesothelioma, Malignant, half reached primary completion within 48 months of starting (the median), counting those still running; a quarter within 29 and three quarters within 87. This study's 32 months is below that.
How these figures are worked out, and which studies are left out of them.
This study is active, not recruiting, as verified in Jun 2026. You cannot join it, but the record below documents what was studied.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
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Studies of the drug tested here: Tremelimumab