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A trial vaccine is showing promise for treating aggressive forms of several cancers, including, ovarian, bowel, prostate and gastroesophageal cancers. The experimental shot teaches the immune system to recognize cells that are multiplying out of control due to a mutation along the HER2 gene. In about 25 percent of breast cancers, HER2 mutations make the tumors grow more aggressively, and dramatically increase the risks that the disease will come back, even after remission.
The vaccine has stopped growth in 54 percent of HER2 tumors in small trial and even eradicated one woman’s ovarian cancer for 18 months over the course of the newly-published clinical trial. A new immunotherapy shot at least temporarily slowed growth and suppressed HER2 cells that make about a quarter of breast cancers more aggressive. Thenew vaccine extends survival times for most patients, but it doesn’t work for every HER2-positive patient.
It is also fairly toxic, causing a host of side effects, such as nausea, rashes, diarrhea, headaches, joint pain and more. To test the new cancer vaccine, the researchers recruited 11 late stage patients with other HER2-associated cancers, because nearly every HER2 breast cancer patient takes Herceptin or a related drug.
The new immunotherapy vaccine may involves a less grueling treatment plan. It was administered over the course of six months. Patients got one dose every four weeks for the first three doses, then the last two doses eight weeks apart. The method involves extracting immune cells from a patient, altering them in the laboratory so they can ‘see’ a protein common to many cancers called HER2, and then reinjecting the cells.
Because the treatment is developed using the patient’s cells, it tends to be better tolerated and to more precisely target the cancers. The trial was small, but for six of the patients, tumor growth was stopped in its tracks for four patients with metastatic ovarian, gastroesophageal, prostate and bowel cancers. Another patient’s tumors shrank for more than four months, before starting to grow again. And the vaccine worked so well in one that after two years, she was cancer-free. When the cancer did come back, it no longer expressed the HER2 cells.