When 71-year-old Maureen Sideris was diagnosed with oesophageal cancer, she expected the worst, surgery, chemotherapy, the full gruelling ordeal she’d endured for colon cancer years before. Instead, she received a short infusion of a drug every three weeks for four months. Then her tumour was simply gone. No surgery. No radiation. No chemo.
“It’s almost like science fiction,” she said. Except it isn’t.
Immunotherapy: the approach of turbocharging the body’s own immune system to hunt down and destroy cancer, is having a genuine moment. After more than a century of painstaking research, it is finally delivering results that oncologists describe with barely concealed emotion. “I get choked up,” says one leading researcher. “We’re talking about cures.”
How It Works
The immune system is already in the business of identifying and destroying rogue cells, including cancerous ones. The problem is that cancer cells are cunning. They camouflage themselves, mimicking healthy tissue, or actively switch off the immune response that would otherwise kill them. Immunotherapy’s job is to expose that trick.
The two best-known approaches are CAR T-cell therapies, where a patient’s immune cells are extracted, genetically reprogrammed in a lab to recognise cancer, and reinfused, and immune checkpoint inhibitors, drugs that remove the “off switch” cancer cells exploit to evade detection. The scientists behind checkpoint inhibitors won the Nobel Prize in 2018, and both approaches are already in clinical use.
But neither is perfect. CAR T-cell therapies are expensive, complex, and have so far struggled against solid tumours, which make up over 90% of cancer diagnoses. Checkpoint inhibitors can produce a wide range of side effects, since disabling immune brakes can also cause the body to attack its own healthy tissue. And crucially, only around 20–40% of patients respond to immunotherapy at all, meaning the majority endure the downsides without the benefit.
The Push for Better Results
Researchers are attacking the response-rate problem from multiple directions. Diet appears to play a role, high-fibre eating may improve outcomes through the gut microbiome. Statins, cheap cholesterol drugs, are showing unexpected potential as boosters. Even the time of day treatment is administered may matter.
Combining immunotherapy with radiation or ultrasound is another promising avenue. Radiation can essentially make tumours more visible to the immune system, helping it recognise what was previously hidden.
The most exciting shift, though, is towards personalisation. Cancer is not one disease, it’s closer to 200, each arising differently and requiring different treatment. Even two patients with identical diagnoses may have fundamentally different cancers at the cellular level. The field is increasingly moving away from treating the disease and towards treating the individual.
Tumours Disappearing Without Surgery
The results from personalised approaches are, in some cases, remarkable. At Memorial Sloan Kettering Cancer Center in New York, researchers identified that tumours carrying a specific genetic signature respond exceptionally well to checkpoint inhibitors like dostarlimab. Across 103 patients with various cancers, oesophageal, bladder, stomach and others, bearing this signature, 84 saw their tumours completely disappear after treatment, with only two requiring any surgery at all. Sideris was among them.
The catch? Only around 5% of tumours carry this genetic profile. Finding equivalent options for the other 95% remains the central challenge of the field.
The Vaccine Frontier
One avenue gaining serious momentum is personalised cancer vaccines. Unlike preventive vaccines, these would be used to treat existing disease, training the immune system to recognise the specific proteins on a patient’s own tumour cells. Early results are encouraging: a small trial at Dana-Farber Cancer Institute produced personalised vaccines for kidney cancer patients after surgery, and all nine remained cancer-free years later. Similar promise has been seen in melanoma.
The Road Ahead
Caution is warranted. Many exciting early-phase results in oncology have failed to translate into approved treatments. Some patients may simply not respond to any form of immunotherapy, cancers have different strengths, and the immune system is a better opponent for some than others.
But the direction of travel is unmistakable. For patients who do respond, immunotherapy is already transforming what cancer treatment looks and feels like, less invasive, more targeted, and in some cases resulting in complete remission where surgery once seemed the only option.
As Sideris put it, one of her doctors told her that in ten years, chemotherapy and radiation may feel as antiquated as bloodletting. Given what she just lived through, it’s hard to argue with that.