An immunotherapy drug to bolster a T cell surge
MD Anderson Melanoma Moon Shot researchers are combining two immunotherapies for the first time to double-team melanoma that has spread to other organs and resisted all forms of treatment.
Patients in a first-of-its-kind clinical trial will receive a vastly expanded dose of their own T cells ¡ª white blood cells that are the specialized warriors of the immune system ¡ª followed by a cancer immunotherapy drug known to promote the activation and survival of T cells.
¡°We¡¯re excited about this combination because there¡¯s no standard of care now for our metastatic melanoma patients if immune checkpoint blockade drugs fail,¡± says clinical trial leader Rodabe Amaria, M.D., assistant professor of Melanoma Medical Oncology.
Checkpoint blockade drugs allow the immune system to unleash T cells to attack tumors. The drugs work by blocking molecules on T cells that act as brakes, which prevent the immune system from launching an attack. To date, researchers have developed two types of drugs that target two separate brakes. Brake No. 1 is called CTLA-4 and brake No. 2 is named PD1. The drugs have revolutionized melanoma treatment, producing powerful and lasting responses in about 10% to 30% of patients who take one drug only, and in more than 50% of those who take both drugs combined.
That still leaves substantial numbers of patients in need of a new approach. For checkpoint blockade to work, there have to be T cells primed and willing to attack the cancer.
Enter T cell expansion and infusion. T cells that attempt to kill cancer are often found in tumors that are removed or biopsied. There just aren¡¯t enough of them to succeed.
Patrick Hwu, M.D., head of Cancer Medicine and chair of Melanoma Medical Oncology, pioneered an approach that grows T cells on slices of a patient¡¯s tumor in the lab, expands them to billions of cells over a few weeks, then infuses them back into the patient. The cells are called tumor-infiltrating lymphocytes, or TILs.
¡°We¡¯ve treated about 100 patients with TILs. About 45 percent respond, and some of those responses last for years,¡± Amaria says. ¡°There¡¯s a lot of room for improvement.¡±
Patients in Amaria¡¯s trial receive T cell expansion followed by a checkpoint blockade drug that blocks PD1. The trial is the first to combine TILs with a PD1 inhibitor.
This double-whammy combination may also stimulate small proteins that fire up the immune system, according to research conducted in Hwu¡¯s lab by Weiyi Peng, M.D., Ph.D. In the clinical trial, 36 patients with metastatic melanoma will have surgery, so their tumor-attacking T cells can be expanded and then frozen. They¡¯ll then be hospitalized and treated with chemotherapy to reduce their existing T cells before being infused with their TILs.
After that, they¡¯ll receive interleukin-2, an immune stimulating protein, to bolster immune response. Three weeks later, they¡¯ll receive the PD1 inhibitor drug Keytruda.
Patients¡¯ tumors are biopsied once before and at least twice after treatment.
¡°Biopsies are a priceless learning opportunity,¡± Amaria says. ¡°It¡¯s so important to see what¡¯s happening in tumors throughout the course of treatment so we can understand and improve how we manage disease.¡±












