ImmunoCellular Therapeutics, Ltd. (IMUC) announced the results of a study in which it was shown that certain specific antigens are highly expressed on cancer stem cells (CSCs). This suggests that IMUC’s lead cancer vaccine product candidate ICT-107, which targets those antigens, may effectively target not only the cells that make up the bulk of certain cancerous tumours, but also the CSCs that are widely believed to give rise to them and cause their recurrence.

The CSCs used in IMUC’s study were isolated from the tumours of five patients with glioblastoma multiforme (GBM), the most common and aggressive type of brain cancer. These CSCs were found to have significantly higher expressions of three antigens targeted by ICT-107—Her-2/neu, AIM2, and TRP-2—than the cells that make up the bulk of the tumour.

“This new evidence that ICT-107 may arm the immune system against cancer stem cells— in addition to the cells that make up the rest of the tumor—builds on the strong data from our phase I study of the vaccine in glioblastoma,” said John Yu, MD, IMUC’s chairman and chief scientific officer. “We believe that the ability to target cancer stem cells is critical to preventing disease recurrence.”

Manish Singh, PhD, president and CEO of IMUC, added, “Cancer stem cells are like the roots of weeds—they may be undetectable after the tumour is resected, but if they are not effectively targeted, the tumour will almost certainly come back. We believe the ability of ICT-107 to target cancer stem cells meaningfully differentiates it from other cancer vaccines in development.” In a recent Phase I study of ICT-107 in GBM, newly diagnosed patients who received the vaccine demonstrated a 12-month increase in progression-free survival (PFS) after surgery. This compared favourably with the historical median PFS of 6.9 months observed with standard treatment with surgery, radiation and chemotherapy. Seven of the 16 patients who participated in the study continue to survive with no disease progression after more than two years.

ICT-107 is a dendritic-cell based vaccine that works by activating a patient’s immune system against specific tumour-associated antigens. This is accomplished by extracting dendritic cells from a patient, loading them with the antigens, and reintroducing them to the patient’s body to trigger an immune response.

The six tumour-associated antigens used in ICT-107 are AIM2, Her-2/neu, gp-100, MAGE-1, TRP-2 and IL13Ra2. These antigens are highly expressed in GBM as well as a number other types of cancer, including breast, pancreatic, colon and melanoma. ICT-107 may, therefore, be applicable to multiple cancer types.

IMUC is a Los Angeles-based clinical-stage company that is developing immune-based therapies for the treatment of brain and other cancers. The company recently completed a phase I trial of its lead product candidate, ICT-107, a dendritic cell-based vaccine targeting multiple tumour associated antigens for glioblastoma.