A Phase 1 interventional study of 21.15.GPC3-CAR T cells in Hepatoblastoma, Hepatocellular Carcinoma and Wilms Tumor, sponsored by Baylor College of Medicine. Recruiting at 1 site in United States. Open to participants aged Up to 21 Years. Per ClinicalTrials.gov, last updated 2025-11-03.
Sponsored by Baylor College of Medicine · Phase 1, Interventional, and Treatment
The body has different ways of fighting infection and disease. No single way seems perfect for fighting cancers. This research study combines two different ways of fighting cancer: antibodies and T cells.
Antibodies are types of proteins that protect the body from infectious diseases and possibly cancer. T cells, also called T lymphocytes, are special infection-fighting blood cells that can kill other cells, including cells infected with viruses and tumor cells. Both antibodies and T cells have been used to treat patients with cancers. They have shown promise but have not been strong enough to cure most patients.
In order to get them to kill cancers more effectively, in the laboratory, the study team inserted a new gene called a chimeric antigen receptor (CAR) into T cells that makes them recognize cancer cells and kill them. When inserted, this new CAR T cell can specifically recognize a protein found on solid tumors, called glypican-3 (GPC3). To make this GPC3-CAR more effective, the study team also added two genes called IL15 and IL21 that help CAR T cells grow better and stay in the blood longer so that they may kill tumors better. When the study team did this in the laboratory, they found that this mixture of GPC3-CAR,IL15 and IL21 killed tumor cells better when compared with CAR T cells that did not have IL15 plus IL21 in the laboratory. This study will use those cells, which are called 21.15.GPC3-CAR T cells, to treat patients with solid tumors that have GPC3 on their surface.
The study team also wanted to make sure that they could stop the 21.15.GPC3-CAR T cells from growing in the blood should there be any bad side effects. In order to do so, they inserted a gene called iCasp9 into the CO-EXIST T cells. This allows us the elimination of 21.15.GPC3-CAR T cells in the blood when the gene comes into contact with a medication called AP1903. The drug (AP1903) is an experimental drug that has been tested in humans with no bad side-effects. This drug will only be used to kill the T cells if necessary due to side effects .
The study team has treated patients with T cells that include GPC3. Patients have also been treated with IL-21 and with IL-15. Patients have not been treated with a combination of T cells that contain GPC3, IL-21 and IL-15. To summarize, this study will test the effect of 21.15.GPC3-CAR T cells in patients with solid tumors that express GPC3 on their surface.
The 21.15.GPC3-CAR T cells are an investigational product not yet approved by the Food and Drug Administration.
The study team will collect up to 18 teaspoons of patients' blood. This will be used this blood to grow T cells. The study team then grows the T cells and uses a retrovirus (a special virus that can insert the GPC3 CAR and IL15 plus IL21 genes into the T cells) to genetically engineer (generate cells in the laboratory) them. After the CAR and IL15 plus IL21 genes are put into the T cells, the study team ensures that they could kill GPC3 positive solid tumor cells in the laboratory.
LYMPHODEPLETION CHEMOTHERAPY:
Several studies suggest that the infused T cells need room to be able to proliferate and accomplish their functions and that this may not happen if there are too many other T cells in the blood . Lymphodepletion chemotherapy is a way of temporarily decreasing the amount of the body s T cells , so that CO-EXIST T cells can grow better. with the two lymphodepleting chemotherapy drugs we will use are called cyclophosphamide (Cytoxan) and fludarabine. They will both be given daily for 3 days before receiving the T-cell infusion.
WHAT THE INFUSION WILL BE LIKE:
If you agree to participate in this study, at the time you are scheduled to be treated, the cells will be thawed and injected into you over 5 to 10 minutes. You will receive the CO-EXIST T cells 48 to 72 hours after completing the chemotherapy. You may be given Tylenol (acetaminophen) and Benadryl (diphenhydramine) before the CO-EXIST T cells to prevent a possible allergic reaction.
This is a dose escalation study, which means that the study team does now know the highest dose of 21.15.GPC3-CAR T cells that is safe. To find out, the cells will be given to at least 3 participants at a lower dose. If that is safe, the study team will raise the dose level that is given to the next group of participants. The dose a patient received will get will depend on how many participants get the agent before the patient and how they react. The investigator will tell the patient this information. Since the treatment is experimental, what is likely to happen at any dose is not known.
If after 4 weeks the patient's condition does not get worse, the patient may receive another round of lymphodepleting chemotherapy and infusion of 21.15.GPC3-CAR T cells.
All the treatments will be given by the Center for Cell and Gene Therapy at Methodist Hospital of Houston.
Medical tests before treatment:
Before being treated, the patient will receive a series of standard medical tests:
Medical tests during and after treatment:
The patient will receive standard medical tests when you are getting the infusions and after:
FOLLOW-UP STUDIES:
The study team will follow the patient during and after the injections. To learn more about the way the T cells are working in the patient's body, up to 60 mL (up to 12 teaspoons) of blood will be taken from the patient before the chemotherapy, before the T-cell infusion, 1 to 4 hours after the infusion, 3 to 4 days after the infusion (this time point is optional ) at 1 week, 2 weeks, 4 weeks and 8 weeks after the injection, every 3 months for 1 year, every 6 months for 4 years and then every year for the next 10 years. Total participation time for this study will be 15 years.
During the time points listed above, if the T cells are found in the patient's blood at a certain amount an extra 5mL of blood may need to be collected for additional testing .
The study team will use this blood to look for the frequency and activity of the cells that we have given; that is, to learn more about the way the T cells are working and how long they last in the body. The study team will also use this blood to see if there are any long-term side effects of putting the new gene (chimeric antigen receptor, CAR) into the cells. In addition to the blood draws, because the patient will receive cells that have had a new gene put in them, the patient will need to have long term follow up for 15 years so the study team can see if there are any long-term side effects of the gene transfer.
Once a year, the patient will be asked to have blood drawn and answer questions about their general health and medical condition. The investigators may ask the patient to report any recent hospitalizations, new medications, or the development of conditions or illness that were not present when the patient enrolled in the study and may request that physical exams and/or laboratory tests be performed if necessary.
When tumor biopsy is performed for clinical reasons the study team will request permission to obtain excess sample to learn more about the effects of the treatment on the patient's disease.
In the event of death, the study team will request permission to perform an autopsy (a procedure where a doctor examines the body to look for a cause of death) to learn more about the effects of the treatment on the patient's disease and if there were any side effects from the cells with the new gene.
In addition, the study team will ask for your permission to use tumor biopsy for research purposes only. Associated risk with the biopsy will be discussed with the patient in detail in a procedure specific consent form. The study team will test the sample to see if the 21.15.GPC3-CAR T cells can be found in the tumor and what effect they had on the tumor cells.
If the patient develops a second abnormal cancer growth, significant blood or nervous system disorder during the trial, the study team will request that a biopsy sample of the tissue will be tested.
The remaining blood and/or tissue samples that are not needed directly for the patient could be used to help researchers learn about this disease and/or immune therapy. These specimens and information about the patient's circumstances may be shared with other cancer researchers. Although there will be a record identifying under what circumstances these specimens were obtained, under all circumstances the patient's identity will be kept confidential. There is a small risk for the loss of confidentiality. However, study personnel will make every effort to minimize this risk. Samples will be kept at Baylor College of Medicine until they are exhausted.
82 studies on the registry are indexed under Hepatoblastoma; 17 are open to participants now.
This study's planned enrollment of 21 is below the median of 30 across 60 interventional studies indexed under Hepatoblastoma.
Browse Hepatoblastoma studies →Baylor College of Medicine is the lead sponsor of 747 studies on the registry; 110 are open to participants now.
Of its 84 completed or terminated interventional studies of FDA-regulated products, 45 (54%) have results posted.
Counted across the registry records on this site, refreshed daily.
Procurement Inclusion Criteria:
Procurement Exclusion Criteria:
Treatment Inclusion Criteria:
Treatment 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.
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.
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
A score of how well the liver works in people with liver disease such as cirrhosis: class A is mild, B moderate and C severe.
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.
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.
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.
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.
How quickly the kidneys clear creatinine, a waste product, from the blood. A study may estimate it from a blood test with age, weight and sex (often by the Cockcroft–Gault formula), or measure it using blood and urine collected over a set time. Given in mL/min; higher is better.
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.
Blood tests of how long blood takes to clot. The INR is the prothrombin time (PT) put on a common scale; about 1 is usual for someone not taking a blood thinner.
Criteria often make an exception for people on a blood thinner such as warfarin, whose INR is raised on purpose.
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).
Relapsed: the illness came back after treatment had worked. Refractory: it did not respond to treatment, or stopped responding while still on it.
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.
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.
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.
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.
Life expectancy
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Child-Pugh class
A score of how well the liver works in people with liver disease such as cirrhosis: class A is mild, B moderate and C severe.
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.
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.
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.
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.
Creatinine clearance (CrCl)
How quickly the kidneys clear creatinine, a waste product, from the blood. A study may estimate it from a blood test with age, weight and sex (often by the Cockcroft–Gault formula), or measure it using blood and urine collected over a set time. Given in mL/min; higher is better.
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.
INR, PT and aPTT (clotting tests)
Blood tests of how long blood takes to clot. The INR is the prothrombin time (PT) put on a common scale; about 1 is usual for someone not taking a blood thinner.
Criteria often make an exception for people on a blood thinner such as warfarin, whose INR is raised on purpose.
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.
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.
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.
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.
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.
GPC3-CAR and the IL15 plus IL21 will be administered to patients with GPC3-positive solid tumors.
Genetic: 21.15.GPC3-CAR T cells
Three different dosing schedules will be evaluated. The following dose levels will be evaluated: The following dose levels will be evaluated: DL0: 3x10\^7/m2 DL1: 1x10\^8/m2 DL2: 3x10\^8/m2 DL3: 1x10\^9/m2
Number of Patients with Dose Limiting Toxicity
A dose limiting toxicity is defined as any toxicity that is considered to be primarily related to the GPC3-CAR T cells. Specifically those which are Grade 5; non-hematologic Grade 3-4 not returning to Grade 2 within 72 hours; Grade 2-4 allergic reaction; Hematologic Grade 4 that fails to return to Grade 2 or baseline (whichever is more severe) within 14 days; all grade 4 CRS and neurologic toxicities and grade 3 CRS and neurologic toxicities that fail to return to Grade 1 within 7 days
Time frame: 4 weeks
Percent of Patients with best response as either complete remission or partial remission
Response rates will be estimated as the percent of patients whose best response is either complete remission or partial remission by combining the data from the two patients. To compare with historical data, a 95% confidence interval will be calculated for the response rate
Time frame: 4 weeks
Median T cell persistence
T cell persistence will be measured by PCR
Time frame: 15 years
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