Melanoma is the most aggressive primary skin cancer affecting adolescents and adults. The incidence of melanoma of the skin has been steadily increasing over the past 10 years (76,100 estimated new cases in the United States alone in 2014). Despite the improvements in outcome over the last decade for those with early-stage disease, the outcome remains extremely poor for those with advanced stage disease at diagnosis. 

With the current standard therapy, 10-year survival for patients with metastatic melanoma is less than 10%. It is therefore desirable to develop novel therapies that could improve these disappointing outcomes. Immune system-based therapies have the potential to fulfill this dire need. The high specificity of such immune-based therapies will also make them less toxic, reducing the organ toxicities and other long-term adverse effects endured by cancer survivors. 

Melanoma cells express tumor-specific molecules on their surface referred to as ‘antigens’. Some of these antigens can be used for developing targeted therapies that will specifically recognize and kill the tumor cells without affecting the other healthy cells in the body. We are working on generating immune cells (T cells) from melanoma patients that are specific for two antigens, HER2 and GD2 expressed on melanoma tumor cell surface. Expression of these surface antigens is variable from one patient to the other and in fact, within a single tumor (e.g., some cells will be both HER2 and GD2 positive while others may express either HER2 or GD2 only).  

We and others have found that using T cells specific for a single antigen can hence result in selective survival of those tumor cells that do not express the targeted antigen. This leads to cancer recurrence after therapy. We have previously shown that simultaneous targeting of two tumor-specific antigens using bispecific T cell products improves tumor control. We now propose to target two melanoma antigens, HER2 and GD2, simultaneously, with the goal of decreasing the risk of tumor recurrence.  

To achieve this, we will genetically modify the T cells with a novel bispecific molecule that we have designed and constructed in our laboratory, called ‘TanCAR’. We will further test the function of these bispecific T cells against melanoma cells in the lab and in animal models. Knowledge gained from the current proposal will be used to justify and develop a clinical trial to treat patients with melanoma. Furthermore, the obtained information could have applicability for T cell therapy of other cancers as well.  

Glioblastoma (GBM) is the most common brain cancer and remains largely incurable. The recent identification of chemotherapy and radiotherapy resistant stem cells in GBMs may help explain why conventional therapies are ineffective.  

Immunotherapy may be able to kill GBM stem cells since immune-mediated killing does not rely on the conventional mechanisms of cell killing. HER2 is tumor protein is positive in >80% of GBMs, but not by the normal brain, making it an attractive target for immunotherapy.  

We have shown that HER2-specific T cells from GBM patients kill GBM stem cells and induce remission of GBMs grown in mice. We now wish to evaluate our approach clinically and test if HER2-specific T cells can be safely given to patients with HER2-positive GBMs (Aim 1) and intend to study their will persistence and antitumor activity in the human body (Aim 2).  

While our preclinical studies demonstrated the potent antitumor activity of HER2-specific T cells, tumors recurred in several treated animals. This limitation in T-cell efficacy is most likely due to the inhibitory tumor environment. GBMs (including GBM stem cells) contain high level of the STAT3, a protein which is not only necessary for GBM stem cell survival but also induces the expression of T cell suppressive factors. Thus, Aim 3 will test in preclinical models our hypothesis that combining STAT3 inhibition with HER2-specific T cells will more effectively eradicate GBMs than T cells alone.