In normal adults, cell replication is primarily restricted to tissues, such as the blood forming cells in the bone marrow that must continuously replicate throughout a person’s lifetime. All other tissues in adults can replicate in response to injury, but they do so only as much as needed to repair the injury and then become dormant again. These two types of cells are regulated differently. Cells that replicate only in response to injury use a protein called Cav3, which cells that divide continuously seem to lack.
Cancer is characterized by inappropriate cell replication. With cancer, cells begin dividing as if they were responding to an injury when there isn’t one. As might be expected, this is associated with the Cav3 protein in many types of cancers. Tau’s scientists, as well as others, have shown that in the test tube and experimental animals, drugs that block Cav3 also block cancer cell division. Notably, our drugs do not kill cancer cells like conventional cancer chemotherapies. Instead, these drugs simply stop the cancer cells from dividing and keep the tumor from growing. Tau has named this “Cytostatic Checkpoint Therapy™” and hopes to bring it to the clinic in the future as a maintenance therapy for cancer.
In the near term, Tau is using its drugs to magnify the effect of conventional cancer chemotherapies by what we call “Interlaced Therapy™”. For cells to replicate, they must go through something called the cell cycle. The cell cycle is a complex series of stages by which a single cell makes a copy of its genetic material then divides to become two daughter cells. Repeated, unnecessary passage through this cycle is what cancer cells do and most normal adult cells don’t do. There are several stages in the cell cycle. Most conventional cancer chemotherapies attack cancer cells at one particular stage. Unfortunately, cancer cells aren’t marching through the cell cycle in unison, they are distributed through various stages of the cycle at any given time. Because conventional cancer chemotherapies act at only one stage in this cycle, they can miss all of the cancer cells that aren’t in this stage. This requires that the chemotherapy drugs be given for long periods of time in order to catch the cancer cells as they cycle through the specific stage at which the conventional drugs are effective. A major drawback to lengthy use of conventional chemotherapeutic drugs is that the patient experiences the negative side effects that go along with them. Even with a longer time of treatment, some cancer cells will escape by being in the “wrong” part of the cell cycle when the conventional chemotherapy drugs are given.
Our drugs appear to stop or slow cell division at a particular stage in the cell cycle. This is probably what is responsible for our drugs’ ability to slow tumor growth in experimental animals. Importantly, this is the stage right before the one in which the cancer cells are attacked by many conventional cancer chemotherapies. By giving one of our drugs to “bunch up” cancer cells at this point and then releasing the cancer cells by removing our drug, a wave of cells progresses through the stage of the cycle that is sensitive to the conventional chemotherapy drug. If the conventional chemotherapy is given at this time, a larger fraction of cancer cells can be killed since more of the cancer cells are entering the sensitive stage. Our studies in experimental animals suggest that this is, indeed, the case.
Interlaced Therapy™ has the potential to reduce the side effects of conventional cancer chemotherapy while increasing its effectiveness. Cytostatic Checkpoint Therapy™ may be used to change cancer into a chronic disease rather than a sudden catastrophe.
Together, we are working to change the face of cancer treatment. Together, we will win against this scourge.