A Phase 1 interventional study of EWSR1 immunotherapy and Pembrolizumab in Ewing Sarcoma and Desmoplastic Small Round Cell Tumor, sponsored by Rabi Hanna. Not yet recruiting at 1 site in United States. Open to participants aged 2 Years and older. Per ClinicalTrials.gov, last updated 2026-09-17.
Sponsored by Rabi Hanna · Phase 1, Interventional, and Treatment
This study is for people who have high-risk Ewing sarcoma (ES), or a related Ewing's family tumor, desmoplastic small round cell tumor (DSRCT). The purpose of this study is to see if a new EWSR1 immunotherapy (a lipid nanoparticle coated with EWSR1 mRNA) which is given as a shot is safe and whether it can help the body's immune system better recognize and fight cancer.
This EWSR1 immunotherapy is designed to target a specific genetic change (EWSR1 fusion gene) that is found in cancer cells but not in normal, healthy cells. Because the EWSR1 gene is broken in cancer cells and the small protein it makes are only in the ES or DSRCT cancer cells, the goal of EWSR1 immunotherapy is to help the immune system identify and attack the cancer without harming normal cells. It is not yet approved by the Food and Drug Administration (FDA).
EWSR1 immunotherapy will be given as a shot into the muscle of the arm, leg, or buttock. If participants also receive pembrolizumab (an infusion every 2 weeks), it is given intravenously (IV) by a needle in the arm over 30 minutes. Participants in this study will receive treatment for about 6 months or until their cancer gets worse. Participants will remain in the study for follow-up for an additional year, for a total time of about 1.5 years in the study.
Ewing sarcoma (ES) is an aggressive type of cancer that has a high risk of spreading to other parts of the body. Even though it often responds well to chemotherapy and radiation at first, it still carries the risk of coming back and/or spreading. Children and young adults whose cancer is limited to one area generally have a better outlook with overall survival at about 75%. However, outcomes are much worse for adults and for people whose cancer has already spread, returned after treatment, or relapsed. In these groups, overall survival is only about 15-25%. People with relapsed or metastatic ES, who make up nearly half of all cases, still need better treatments than the current standard of care. More effective therapies are needed to achieve longer-lasting results.
Desmoplastic small round cell tumor (DSRCT) is a rare cancer that belongs to the Ewing family of tumors. It often spreads widely throughout the abdomen. Like Ewing sarcoma, DSRCT often responds to chemotherapy and radiation at first. However, even with standard of care treatment, long-term outcomes remain poor. Overall survival is only about 10-15%, and the cancer frequently returns in additional, outside areas. Because current treatments have had limited success, there is an urgent need to develop new targeted therapies that can more effectively treat these cancers.
Both ES and DSRCT are driven by recurrent, highly conserved gene fusion events that create neoantigens. Conventional therapies are often unable to target these gene events, and thus are unable to effectively treat the cause of the cancer. However, because these fusion events create proteins that are required for tumor survival and generate unique tumor-specific neoantigens that are absent from normal tissues, they represent highly attractive targets for immunotherapeutic approaches. Recent advances in immuno-oncology have highlighted the promise of tumor-specific neoantigens, particularly those arising from gene fusions, as targets for precision immunotherapy. Our group has been at the forefront of defining the importance of tumor mutations and neoantigens in cancer therapy.
The overall goal of this study in using EWSR1 immunotherapy without or with anti-PD1 is to develop cancer-specific long-lasting immunity against EWSR1 neoantigens. Adding anti-PD1 will be done because of concern that monotherapy may not overcome tumor inhibitory microenvironment (TIME) and T-cell exhaustion. Therefore, it is hypothesized that this combination will be safe because of the known safety profiles of other immunotherapy interventions with anti-PD1.
250 studies on the registry are indexed under Sarcoma, Ewing; 69 are open to participants now.
This study's planned enrollment of 24 is below the median of 36 across 204 interventional studies indexed under Sarcoma, Ewing.
Browse Sarcoma, Ewing studies →This is the only study on the registry with Rabi Hanna as lead sponsor.
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.
Participants must have adequate organ and marrow function as defined below:
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.
Relapsed: the illness came back after treatment had worked. Refractory: it did not respond to treatment, or stopped responding while still on it.
Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.
The amount of disease can be tracked with a defined measurement, so the study can see whether it shrinks or grows. It might be a tumour measured on a scan or, in some blood cancers such as myeloma, a marker measured in blood or urine.
The criteria or the study team say which measurement counts — having no tumour visible on a scan does not by itself rule you out.
Versions of RECIST adapted to particular cases. iRECIST is for immunotherapy, where a tumour can look bigger for a while before it shrinks, so growth has to be confirmed on a later scan. mRECIST usually means the version for liver cancer (hepatocellular carcinoma), which measures only the part of a tumour that still has a blood supply.
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.
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 number of neutrophils, white blood cells that help fight infection, in a given amount of blood. Too few raises the risk of infection.
It is a count, not a percentage of the white cells. Limits are written in units that mean the same: ≥ 1.5 × 10⁹/L is ≥ 1,500 per mm³ (µL). Each lab has its own reference range.
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.
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
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.
Cancer deposits in the brain from a cancer that started elsewhere in the body (CNS metastases include the spinal cord).
Studies differ: some leave out any brain metastases, some accept ones treated and stable for some weeks. Check what this study allows.
Cancer that has spread to the leptomeninges, the thin layers covering the brain and spinal cord, and the fluid between them. It is not the same as brain metastases.
Criteria often treat it separately, and many studies leave it out even where treated brain metastases are allowed.
A 0–100 scale of how well someone can carry out everyday activities. 100 is no complaints and no signs of illness; 70 is able to look after yourself but not to work or keep up normal activity; 50 is needing considerable help and frequent medical care.
Studies often ask for 60 or 70 and above. Your doctor gives the score.
A planned gap after a treatment, so that its effects can lessen before the study treatment or a study assessment. Ask the study team and the doctor who prescribed it before changing any medicine.
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.
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.
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.
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.
The New York Heart Association’s four classes of how much heart failure limits physical activity.
Studies set their own limit — many outside heart failure leave out class III–IV, while heart failure studies may ask for a particular class. Check the class this study names.
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.
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.
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.
Measurable disease
The amount of disease can be tracked with a defined measurement, so the study can see whether it shrinks or grows. It might be a tumour measured on a scan or, in some blood cancers such as myeloma, a marker measured in blood or urine.
The criteria or the study team say which measurement counts — having no tumour visible on a scan does not by itself rule you out.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
iRECIST and mRECIST
Versions of RECIST adapted to particular cases. iRECIST is for immunotherapy, where a tumour can look bigger for a while before it shrinks, so growth has to be confirmed on a later scan. mRECIST usually means the version for liver cancer (hepatocellular carcinoma), which measures only the part of a tumour that still has a blood supply.
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.
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.
Absolute neutrophil count (ANC)
The number of neutrophils, white blood cells that help fight infection, in a given amount of blood. Too few raises the risk of infection.
It is a count, not a percentage of the white cells. Limits are written in units that mean the same: ≥ 1.5 × 10⁹/L is ≥ 1,500 per mm³ (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.
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.
Hemoglobin (Hb)
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Bilirubin
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ULN (upper limit of normal)
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ALT and AST (liver enzymes)
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
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.
Brain metastases
Cancer deposits in the brain from a cancer that started elsewhere in the body (CNS metastases include the spinal cord).
Studies differ: some leave out any brain metastases, some accept ones treated and stable for some weeks. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Leptomeningeal disease
Cancer that has spread to the leptomeninges, the thin layers covering the brain and spinal cord, and the fluid between them. It is not the same as brain metastases.
Criteria often treat it separately, and many studies leave it out even where treated brain metastases are allowed.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Karnofsky performance status (KPS)
A 0–100 scale of how well someone can carry out everyday activities. 100 is no complaints and no signs of illness; 70 is able to look after yourself but not to work or keep up normal activity; 50 is needing considerable help and frequent medical care.
Studies often ask for 60 or 70 and above. Your doctor gives the score.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Washout period
A planned gap after a treatment, so that its effects can lessen before the study treatment or a study assessment. Ask the study team and the doctor who prescribed it before changing any medicine.
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.
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.
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.
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.
NYHA class (heart failure)
The New York Heart Association’s four classes of how much heart failure limits physical activity.
Studies set their own limit — many outside heart failure leave out class III–IV, while heart failure studies may ask for a particular class. Check the class this study names.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
First, a safety cohort of participants will be enrolled in the study. Participants will receive EWSR1 immunotherapy on Weeks 0, 4, 12 and 24.
Drug: EWSR1 immunotherapy
After safety is established through the monotherapy cohort, participants will be enrolled in the combination cohort. Participants will receive EWSR1 immunotherapy on Weeks 0, 4, 12 and 24. Participants will also receive pembrolizumab (anti-PD1) on Week 0 and then every 2 weeks for 6 months.
Drug: EWSR1 immunotherapy · Drug: Pembrolizumab
Participants will receive EWSR1 immunotherapy at 50 micrograms (mcg) (or 25 mcg for children 12 years and younger) through an intramuscular injection on Weeks 0, 4, 12 and 24.
Participants will receive Pembrolizumab (anti-PD1) at 3 milligram per kilogram (mg/kg) intravenously (through an IV) on Week 0 and Week 4.
Also known as: anti-PD1
Safety of EWSR1 immunotherapy, measured by number of participants with grade 4 immunotherapy-related adverse events
Safety will be achieved in the EWSR1 immunotherapy monotherapy cohort if no participant has grade 4 EWSR1 immunotherapy-related toxicity
Time frame: Up to 6 months
Safety of combination therapy (EWSR1 immunotherapy + pembrolizumab), measured by number of participants with grade 3 drug related adverse events lasting greater than 1 week
In the combination therapy cohort (EWSR1 immunotherapy + pembrolizumab) cohort, safety will be achieved if participants without progression at 6 months have no grade 3 drug related AE lasting \> 1 week
Time frame: Up to 6 months
Feasibility of EWSR1 immunotherapy monotherapy, measured by proportion of participants who receive doses
Feasibility will be achieved in the EWSR1 immunotherapy monotherapy cohort if participants receive at least 3 of 4 proposed doses.
Time frame: Up to 6 months
Feasibility of combination therapy (EWSR1 immunotherapy + pembrolizumab), measured by number of participants who receive at least 3 months of therapy
In the combination therapy cohort (EWSR1 immunotherapy + pembrolizumab) cohort, feasibility will be achieved if 12 participants receive at least 3 months of combination therapy.
Time frame: Up to 6 months
Progression free survival (PFS)
PFS will be assessed using iRECIST (Immunologic Response Evaluation Criteria in Solid Tumors) criteria and is defined as the duration of time from start of treatment to time of progression or death, whichever occurs first.
Time frame: Up to 1.5 years
Overall survival (OS)
OS is defined as the time from start of treatment until death from any cause.
Time frame: Up to 1.5 years
Tumor response, as measured by change in tumor volume
Tumor responses will be determined comparing chest CT (Computed Tomography) and PET-CT (Positron Emission Tomography - Computed Tomography) scans. Trends of lesion size will be depicted using waterfall and "spaghetti" plots showing and tumor volume differences over time.
Time frame: Baseline, month 6
Plan to share: Yes — All side effects of each participant are to be documented in Epic and available Cleveland Clinic monitoring and FDA audit, if needed. For patients getting vaccine + checkpoint inhibition safety and efficacy data (without patient identifiers) will be shared with Agenus, supplier of the antiPD1 antibodies.
Supporting information: Study protocol, Clinical study report
Time frame: Data will be available in in a timely, proactive manner to allow monthly Cleveland Clinic study monitoring and also to be ready for any potential FDA audit
Access criteria: on site for Cleveland Clinic Monitoring
Start is estimated for Oct 2026; primary completion for Oct 2029, 36 months later.
Of 41 phase 1 interventional studies under Sarcoma, Ewing, half reached primary completion within 89 months of starting (the median), counting those still running; a quarter within 65 and three quarters within 134. This study's planned 36 months is below that.
How these figures are worked out, and which studies are left out of them.
This study is not yet recruiting, as verified in Sep 2026. You cannot join it, but the record below documents what was studied.
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