Immunotherapy is decades old, but in recent years, a series of new drugs and treatments has some calling the treatment the dawn of a new era in cancer care. "Immunotherapy is not new in the field of cancer treatment," says Eugene Ahn, MD, a Hematologist/Oncologist in our Chicago hospital. "But what has generated tremendous excitement in the last few years is the success stories of patients with metastatic melanoma and lung cancer who have been able to achieve lasting, positive results with a new class of immunotherapy drugs."
Former President Jimmy Carter is one of the most high-profile examples. In August 2015, Carter announced he had been diagnosed with metastatic melanoma that had spread to his liver and brain. Four months later, after undergoing immunotherapy treatment, Carter announced that a recent brain scan revealed no signs of cancer.
"President Carter’s case has definitely brought the discussion of immunotherapy more to the forefront," says Dr. Glen Weiss, Director of Clinical Research and Medical Oncologist at our Phoenix hospital. "Patients are coming to consultation appointments with some degree of knowledge about it and asking the appropriate questions: Am I a candidate for immunotherapy? Do you have a clinical trial with immunotherapy that I can participate in?"
The buzz around checkpoint inhibitors
Pembrolizumab (Keytruda®), used to treat former President Jimmy Carter’s metastatic melanoma, nivolumab (Opdivo®) and ipilimumab (Yervoy®), are among the so-called "checkpoint inhibitor" drugs that have been adding to the buzz around immunotherapy. Designed to stimulate the immune system to target certain cancer cells, these drugs have been approved to treat melanoma, kidney and/or lung cancers. Trials on a variety of other cancers are in the works.
Checkpoint inhibitors work by rewiring specific T-cell receptors in the immune system. The receptors normally act as brakes and accelerators, slowing or speeding up the T-cells as they travel through the body in search of invaders. The immunotherapy drugs now on the market target disrupt a specific receptor’s signal and prevent it from applying the brakes. This allows the T-cells to accelerate past the checkpoints and attack the cancer cells.
Even though checkpoint inhibitor immunotherapy drugs have the medical and scientific communities hopeful about the future, many questions remain about this still-evolving area of cancer treatment. To help solve these and other mysteries, doctors and researchers are testing theories and suppositions in clinical trials. “Clinical trials are evaluating the safest doses, schedules, duration and combination of these treatments to improve on the results of already-approved drugs and to increase the percentage of patients who will not only have a response to immunotherapy, but, hopefully, a long, durable response measured in years, not weeks or months,” Dr. Weiss says.
What's on the horizon
A series of trials, for example, is exploring the effectiveness of immunotherapy on patients with varying cancer types, while also determining how to combine treatments to produce positive results. "For now, we do not have a great way of selecting patients who are more likely to benefit, but teams of researchers on working on this," says Dr. Weiss. "Right now, these medicines are given to patients with advanced, metastatic disease who would also be considered appropriate candidates for other systemic therapy, such as chemotherapy."
In January, our Phoenix hospital launched a new clinical trial testing the effectiveness of combining the immunotherapy drug nivolumab with certain chemotherapy drugs to treat specific types of colorectal cancer and pancreatic cancer. The study will consider how immunotherapy and chemotherapy combinations perform on other advanced cancers. In another clinical trial launched in December 2014, Dr. Weiss and fellow researchers found that combining pembrolizumab with traditional chemotherapy achieved better results for some patients with advanced small cell lung cancer and non-small cell lung cancer than chemotherapy alone. The study has since expanded to include research on how the combination performed in treating sarcoma patients and other advanced cancers.
