Novel Anti-Tumor Vaccine Developed

The vaccine utilizes the tumor's own protein to induce an immune system response, allowing for a personalized approach to treatment.

The new approach was developed by scientists and clinicians at Children's [U.S.] National Medical Center (Washington DC, USA) in collaboration with investigators from the University of Iowa (Iowa City, Iowa, USA). The vaccine and delivery system, developed in the laboratory of Anthony Sandler, M.D., chief of general and thoracic surgery at Children's, involves the creation of synthetic microparticles, known as immune stimulatory antigen-loaded particles (ISAPs), that consist of tumor antigens (proteins) from the specific tumor to be targeted, as well as immune stimulatory agents. The ISAPs are detected and engulfed by specialized immune cells and sensed to be immune-stimulating foreign bodies.

The study demonstrated that ISAPs are effective at blocking the growth of tumors in mice by inducing activation of immune cells that then stimulate the immune system to specifically target the tumor whose antigens match those that are loaded in the particles-- known as tumor specific immunity.

The researchers also discovered, however, that the impact of ISAPs on tumor growth was partially mitigated by an increased presence of regulatory T-cells (T-reg) when ISAPs are introduced into the body. The researchers believe that T-regs play a key role in how the vaccine affects tumor growth by suppressing the development of the specific immune cells needed to fight the tumor. By adding a T-reg suppressor such as cyclosphosphamide or anti-CD25 antibody, the scientists were able to have a greater impact on preventing tumor growth using the ISAP approach.

"For tumors like neuroblastoma, reduction to minimal residual disease with standard therapies like chemotherapy and/or surgical resection and subsequent treatment with this vaccine could quite possibly cure the patient of the disease in the not too distant future,” said Dr. Sandler, lead author of the study. "Creation of ISAPs allows us to target our treatments to the specific tumor of interest, a capability that will more effectively combat a wide range of these tumors in a personalized fashion.”

The study was published in the October 2008 issue of the research journal Cancer Immunology, Immunotherapy.

Related Links:
Children's National Medical Center
University of Iowa