PSMA/CD70 Bi-specific CAR-T Cell Therapy

Patients with refractory and/or recurrent cancer have poor prognosis despite complex multimodal therapy; therefore, novel curative approaches are needed. The investigators attempt to use T cells genetically modified to express a 4th generation lentiviral anti-PSMA/CD70 bi-specific chimeric antigen receptor (bi-4SCAR-PSMA/CD70). The chimeric antigen receptor (CAR) molecules enable the T cells to recognize and kill tumor cells through the recognition of a surface antigen, CD70 or PSMA, which is expressed at high levels on tumor cells but not at significant levels on normal tissues.

CD70 is a promising therapeutic target due to its restricted expression in normal tissues and overexpression in malignant tissues. Expression of CD70 was observed on multiple tumor types including kidney, breast, esophageal, liver, colon cancer, glioma, lymphoma as well as melanoma. In addition, it has been reported that anti-CD70 CAR T-cell therapy eliminated primary CD70-positive cells and had strong anti-tumor effects in preclinical animal models. The CD70 targeted CAR-T cells with binding moiety of CD70 specific scFv exhibit a higher affinity and antitumor effect against CD70+ tumor cells.

Prostate-specific membrane antigen (PSMA) is expressed in normal prostate and upregulated in prostate tumor. However, PSMA is not restricted to prostate cancer and it is known that PSMA is enriched in the tumor stromal environment. Based on immunostaining, it is confirmed that PSMA is expressed in a variety of solid tumors, including brain tumor, neuroblastoma and some lymphomas. Therefore, PSMA is a promising target for immunotherapy of many types of cancer.

A potential strategy to prevent relapse due to antigen escape is to infuse T-cells capable of recognizing multiple antigens. To overcome tumor escape of single target antigen and enhance in vivo CAR-T efficacy, a novel bi-specific PSMA/CD70 CAR-T therapy regimen is developed to include booster and consolidation CAR-T applications to target highly-refractory cancer. The aim is to evaluate safety and long term efficacy of the bi-CAR-T therapy strategy in CD70 and/or PSMA positive cancer patients.

Inclusion criteria

• Patients with tumor cells have received standard first-line therapy and have been judged to be non-resectable, metastatic, progressive or recurrent.
• The expression status of CD70 or PSMA antigens in the tumor tissue will be determined for eligibility. Positive expression is defined by CD70 and PMSA antibody staining results based on immunohistochemistry or flow cytometry analyses.
• Body weight greater than or equal to 10 kg.
• Age: ≥1 year and ≤ 75 years of age at the time of enrollment.
• Life expectancy: at least 8 weeks.
• Prior Therapy:

There is no limit to the number of prior treatment regimens. Any grade 3 or 4 non-hematologic toxicity of any previous therapy must be resolved to grade 2 or less.

• Participant must not have received hematopoietic growth factors for at least 1 week prior to mononuclear cells collection.
• At least 7 days must have elapsed since the completion of therapy with a biologic agent, selected targeted agent or a metronomic non-myelosuppressive regimen.
• At least 4 weeks must have elapsed since prior therapy that included a monoclonal antibody.
• At least 1 week since any radiation therapy at the time of study entry.
• Karnofsky/jansky score of 60% or greater.
• Cardiac function: Left ventricular ejection fraction greater than or equal to 40/55 percent.
• Pulse Ox greater than or equal to 90% on room air.
• Liver function: defined as alanine transaminase (ALT) <3x upper limit of normal (ULN), aspartate aminotransferase (AST) <3x ULN; serum bilirubin and alkaline phosphatase <2x ULN.
• Renal function: Patients must have serum creatinine less than 3 times upper limit of normal.
• Marrow function: White blood cell count ≥1000/ul, Absolute neutrophil count ≥500/ul, Absolute lymphocyte count ≥500/ul, Platelet count ≥25,000/ul (not achieved by transfusion).
• Patients with known bone marrow metastatic disease will be eligible for enrollment as long as they meet hematologic function criteria, and the marrow disease does not have hematologic toxicity.
• For all patients enrolled in this study, themselves or their parents or legal guardians must sign an informed consent and assent.

Exclusion criteria

• Existing severe illness (e.g. significant cardiac, pulmonary, hepatic diseases, etc.) or major organ dysfunction, or greater than grade 2 hematologic toxicity.
• Untreatable central nervous system (CNS) metastasis: Patients with previous CNS tumor involvement that has been treated and is stable for at least 4 weeks following completion of therapy are eligible.
• Previous treatment with other genetically engineered CD70 or PSMA-specific CAR T cells.
• Active HIV, hepatitis B virus (HBV), hepatitis C virus (HCV) infection or uncontrolled infection.
• Patients who require systemic corticosteroid or other immunosuppressive therapy.
• Evidence of tumor potentially causing airway obstruction.
• Inability to comply with protocol requirements.
• Insufficient CAR T cells availability.