Immunotherapy to Treat Cancer (2025): Types, Benefits, Risks, and Latest Breakthroughs

Cancer immunotherapy represents a major paradigm shift in oncology — mobilizing a patient's own immune system to recognize and attack cancer cells, rather than relying solely on surgery, radiation, or cytotoxic chemotherapy. It has emerged as a fourth pillar of effective cancer treatment, offering durable responses and, in select cancers, the potential for long-term remission.


Immunotherapy became widely known when former President Jimmy Carter’s medical team used it to treat his metastatic melanoma cancer. When the former president announced in August, 2015 that malignant tumors had been found in both his liver and his brain, most people presumed that he would be dead within months. But just four months later he surprised the world with the news that, following a remarkable and revolutionary new treatment, there was no sign of cancer in his body. The treatment he received was a drug classified as an “immune checkpoint inhibitor”. This class of medications has kicked off a revolution that has demonstrated that cancer can be cured by your own immune system. It just needs a little help. There are now countless drugs based on this principle.


In this Article:
  • Introduction
  • How does immunotherapy work against cancer?
  • What are the types of immunotherapy?
  • Which cancers are treated with immunotherapy?
  • What are the side effects of immunotherapy?
  • How is immunotherapy given?
  • Where do you go for immunotherapy?
  • How often do you receive immunotherapy?
  • How can you tell if immunotherapy is working?
  • What is the current research in immunotherapy?
  • How do you find clinical trials that are testing immunotherapy?

Introduction

Until very recently we've had three main methods for treating can-cer. We've had surgery for at least three thousand years. We added radiation therapy in 1896' Then in 1946, chemical warfare research led to the use of a mustard gas derivative to kill cancer cells. Those poisons were the foundation for chemotherapy.

These "cut, burn, and poison" techniques are currently estimated to be able to cure cancer in about half of the people who develop the disease. And that's remarkable, a true medical accom-plishment. But that leaves the other half of cancer patients. Last ycar, in the United States alone, that translated to nearly six hundred thousand people who died of the disease.


The fight was never fair. We've been pitting simple drugs against creative mutating versions of our own cells, trying to kill the bad ones while sparing the good ones and making ourselves sick in the process. And we've been doing that for a very long time.

But now we have added a new and very different approach— one that doesn't act directly on cancer, but on the immune system.


Our immune system has evolved over 500 million years into a personalized and effective natural defense against disease. It is a complex biology with a seemingly simple mission: to find and destroy anything that's not supposed to be in our bodies. Cells of the immune system are on constant patrol, hundreds of millions of them circulating throughout the body, slipping in and out of organs, searching out and destroying invaders that make us sick and body cells that have become infected, mutated, or defective— cells like cancer.

Which raiscs the question: Why docsn't the immune system fight cancer already?

The answer is, it does, or tries to. But cancer uses tricks to hide from the immune system, shut down our defenses, and avoid the fight. We don't stand a chance, unless we change the rules.

Cancer immunotherapy is the approach that works to defeat the tricks, unmask cancer, unleash the immune system, and restart the battle. It differs fundamentally from the other approaches we have to cancer, because it does not act upon cancer at all, not directly.

Instead it unlocks the killer cells in our own natural immune system and allows them to do the job they were made for.

Cancer is us. It's the mistake that works. Cells in the body regularly go rogue, their chromosomes knocked out by particles of sunlight or toxins, mutated by viruses or genetics, age, or sheer randomness. Most of these mutations are fatal to the cell, but a few survive and divide. 99.9 percent of the time, the immune system successfully recognizes these mutant cells and kills them. The problem is that rogue o.000 percent cell, the one that the immune system doesn't recognize as an invader and docs not kill. Instead, eventually, that 0.0001 percent cell kills us.


Cancer is different. It does not announce itself like the flu or any other discase, or even a splinter. It doesn't seem to sound an alarm in the house of the body, or provoke an immune response, or show symptoms of immune battle: no fever or inflammation or swollen lymph glands, not even a sniffle. Instead, the tumor is suddenly discovered, an unwelcome guest that has been growing and spreading out, sometimes for years. Often by then it is too late.


To many cancer researchers, this apparent lack of immune response to cancer meant that the goal of helping an immune response to cancer was futile-because there was nothing to help.

Cancer was assumed to be too much a part of our selves to be noticed as "non-self." The very concept of cancer immunotherapy scemed fundamentally flawed.

But throughout history, physicians had recorded rare cases of patients whose cancers apparently cured themselves. In a prescientific age these "spontaneous remissions" were seen as the work of magic or miracle; in fact, they are the work of an awakened immune system. For more than a hundred ycars researchers tried and failed to replicate those miracles through medicine, to vaccinate or spark an immune response to cancer similar to those against other formerly devastating diseases like polio, smallpox, or the flu.

There were glimmers of hope, but no reliable treatments. By the ycar 2000, cancer immunologists had cured cancer in mice hundreds of times, but could not consistently translate those results to people. Most scientists believed they never would.

That changed radically and recently. Even for physicians, this change was invisible until it was at the doorstep. One of our best modern writers on the subject of cancer, Dr. Siddhartha Mukher-jee, does not even mention cancer immunotherapy in his nonetheless excellent Pulitzer Prize-winning biography of the disease, The Emperor of All Maladies. That book was published in 2010, only five months before the first of the new-generation immuno-therapeutic cancer drugs received FDA approval.

That first class of cancer immunotherapy drugs would be called "checkpoint inhibitors." They came from the breakthrough discovery of specific tricks, or "checkpoints," that cancer uses like a secret handshake, telling the immune system, Don't attack. The new drugs inhibited those checkpoints and blocked cancer's secret handshake.

In December 2015 the second of these checkpoint inhibitors' was used to unleash the immune system of former president Jimmy Carter. An aggressive cancer had spread through his body and he wasn't expected to survive; instead, his immune cells cleared the cancer from his liver and brain. The news of the ninety-one-year-old president's miraculous recovery surprised everyone, including the former president himself. For many people, "that Jimmy Carter drug" was the first and only thing they'd heard about cancer immunotherapy.

But the breakthrough isn't any one treatment or drug; it's a series of scientific discoveries that have expanded our understanding of ourselves and this disease and redefined what is possible. It has changed options and outcomes for cancer patients, and opened the door to a rich and uncharted field of medical and scientific exploration.

These discoveries validated an approach to beating cancer that is conceptually different from the traditional options of cut, burn, or poison, an approach that treats the patient rather than the disease.

For the first time in our age-old war with cancer, we understood what we were fighting, how cancer was cheating in that fight, and how we might finally win. Some call this our generation's moon shot. Even oncologists, a cautious bunch, are using the C word: cure.


Hype can be dangerous, just as false hope can be cruel. There's a natural tendency to invest too much hope in a new science, especially one that promises to turn the tables on a disease that has, in some way, touched every person's life. Nevertheless, these aren't overhyped theories or anccdotal wonder cures, but proven medicines based on solid data. Immunotherapy has gone from being a dream to a science.

Right now there are only handful of immunotherapies avail-able. Less than half of all cancer patients have been shown to respond to these drugs. Many who respond do so profound ly, with remissions measured not in extra weeks or months of life, but in lifetimes. Such transformative, durable responses are the unique promise of the cancer immunotherapeutic approach, and part of what makes it attractive to patients, but it's important to note that that promise is different from a guarantee for any one outcome for any individual patient. We still have work to do to widen the circle of responders and truly find a cure. But the door is open now, and we've only just begun.

Several of the immunotherapists I interviewed compared the discovery of these first cancer immunotherapy drugs to that of penicillinS As a drug, penicillin immediately cut infection rates, cured some bacterial diseases, and saved millions of lives. But as a scientific breakthrough, it redefined the possible and opened a fertile new frontier for generations of pharmaceutical researchers. Nearly one hundred years after the discovery of that one simple drug, antibiotics are an entire class of medicines with a global impact so profound that we take it for granted. Invisible terrors that plagued and poisoned mankind for millennia are now casually vanquished at a drive-through pharmacy.

The discoveries of how cancer tricks and hides from the immune system were immunotherapy's penicillin moment. The approval of the first checkpoint-inhibiting drug that regularly and profoundly changed outcomes for cancer patients redefined the direction of scientific inquiry. That's now kicked off a gold rush in research and investment and drug development. Seven years after the approval of that first solitary checkpoint inhibitor there are reportedly 940 "new" cancer immunotherapeutic drugs being tested in the clinic by more than a half million cancer patients in 3,042 clinical trials, with another 1,064 new drugs in the labs in preclinical phase.

Those numbers are dwarfed by the number of trials testing the synergetic effectiveness of immunotherapy combinations. The research is advancing so rapidly that several drug manufacturers have successive generations of drugs stacked up in the clinical trial pipeline like planes waiting for clearance at LaGuardia, requiring new FDA "fast track" and "breakthrough" designations to speed them through the approval process to cancer patients who don't have time to wait. Major advances in cancer usually come in roughly fifty-year increments; cancer immunotherapy has already made a generational leap, seemingly overnight. Describing what is coming next, many scientists smile and use words like "tsunami" and "tidal wave." The pace of progress is rare in the history of modern medicine, unprecedented in our history with cancer. We have an opportunity to fundamentally redefine our relationship with a disease that for too long has defined us.


It is this "landmark in our history with cancer," that the Nobel Committee cited in their decision to award the 2018 Nobel Prize in Medicine to Dr. James P. Allison and Dr. Tasuku Honjo, two immune researchers who discovered some of the tricks cancer uses to evade the immune system. These discoveries "revolutionized cancer treatment, and fundamentally changed the way we view how cancer can be managed."

How does immunotherapy work against cancer?

As part of its normal function, the immune system detects and destroys abnormal cells and most likely prevents or curbs the growth of many cancers. For instance, immune cells are sometimes found in and around tumors. These cells, called tumor-infiltrating lymphocytes or TILs, are a sign that the immune system is responding to the tumor. People whose tumors contain TILs often do better than people whose tumors don’t contain them.


Even though the immune system can prevent or slow cancer growth, cancer cells have ways to avoid destruction by the immune system. For example, cancer cells may: 
  • Have genetic changes that make them less visible to the immune system.
  • Have proteins on their surface that turn off immune cells.
  • Change the normal cells around the tumor so they interfere with how the immune system responds to the cancer cells. 
Immunotherapy helps the immune system to better act against cancer.

Major Types of Cancer Immunotherapy

Several types of immunotherapy are used to treat cancer. These include:
  • Immune checkpoint inhibitors, which are drugs that block immune checkpoints. These checkpoints are a normal part of the immune system and keep immune responses from being too strong. By blocking them, these drugs allow immune cells to respond more strongly to cancer. Learn more about immune checkpoint inhibitors.
  • T-cell transfer therapy, which is a treatment that boosts the natural ability of your T cells to fight cancer. In this treatment, immune cells are taken from your tumor. Those that are most active against your cancer are selected or changed in the lab to better attack your cancer cells, grown in large batches, and put back into your body through a needle in a vein. T-cell transfer therapy may also be called adoptive cell therapy, adoptive immunotherapy, or immune cell therapy. Learn more about T-cell transfer therapy.
  • Natural killer (NK) cell-based immunotherapies are attracting increasing interest in the field of cancer treatment. Early clinical trials have shown promising outcomes, alongside satisfactory product efficacy and safety. Learn more about Natural Killer Cells immunotherapy.
  • Monoclonal antibodies, which are immune system proteins created in the lab that are designed to bind to specific targets on cancer cells. Some monoclonal antibodies mark cancer cells so that they will be better seen and destroyed by the immune system. Such monoclonal antibodies are a type of immunotherapy. Monoclonal antibodies may also be called therapeutic antibodies. Learn more about monoclonal antibodies.
  • Treatment vaccines, which work against cancer by boosting your immune system’s response to cancer cells. Treatment vaccines are different from the ones that help prevent disease. Learn more about cancer treatment vaccines.
  • Immune system modulators, which enhance the body’s immune response against cancer. Some of these agents affect specific parts of the immune system, whereas others affect the immune system in a more general way. Learn more about immune system modulators.

Which cancers are treated with immunotherapy?

Immunotherapy drugs have been approved to treat many types of cancer. However, immunotherapy is not yet as widely used as surgerychemotherapy, or radiation therapy. To learn about whether immunotherapy may be used to treat your cancer, see the PDQ® adult cancer treatment summaries and childhood cancer treatment summaries.

What are the side effects of immunotherapy?

Immunotherapy can cause side effects, many of which happen when the immune system that has been revved-up to act against the cancer also acts against healthy cells and tissues in your body.

Learn more about immunotherapy side effects.

How is immunotherapy given?

Different forms of immunotherapy may be given in different ways. These include:

  • intravenous (IV): The immunotherapy goes directly into a vein.
  • oral: The immunotherapy comes in pills or capsules that you swallow.
  • topical: The immunotherapy comes in a cream that you rub onto your skin. This type of immunotherapy can be used for very early skin cancer.
  • intravesical: The immunotherapy goes directly into the bladder.

Where do you go for immunotherapy?

You may receive immunotherapy in a doctor’s office, clinic, or outpatient unit in a hospital. Outpatient means you do not spend the night in the hospital.

How often do you receive immunotherapy?

How often and how long you receive immunotherapy depends on:

  • your type of cancer and how advanced it is
  • the type of immunotherapy you get
  • how your body reacts to treatment

You may have treatment every day, week, or month. Some types of immunotherapy given in cycles. A cycle is a period of treatment followed by a period of rest. The rest period gives your body a chance to recover, respond to immunotherapy, and build new healthy cells.

How can you tell if immunotherapy is working?

You will see your doctor often. He or she will give you physical exams and ask you how you feel. You will have medical tests, such as blood tests and different types of scans. These tests will measure the size of your tumor and look for changes in your blood work.

What is the current research in immunotherapy?

Researchers are focusing on several major areas to improve immunotherapy, including:

  • Finding solutions for resistance.
    Researchers are testing combinations of immune checkpoint inhibitors and other types of immunotherapy, targeted therapy, and radiation therapy to overcome resistance to immunotherapy.
  • Finding ways to predict responses to immunotherapy.
    Only a small portion of people who receive immunotherapy will respond to the treatment. Finding ways to predict which people will respond to treatment is a major area of research.
  • Learning more about how cancer cells evade or suppress immune responses against them.
    A better understanding of how cancer cells get around the immune system could lead to the development of new drugs that block those processes.
  • How to reduce the side effects of treatment with immunotherapy.

Immunotherapy cancer success rate 

Immunotherapy drugs work better in some cancers than others and while they can be a miracle for some, they fail to work for all patients. Overall response rates are about 15 to 20%. (Source)

Immunotherapy Fails When Certain Microbes Are Absent

Researchers have also explored the influence of gut bacteria on cancer patients' responses to checkpoint inhibitors — a class of immunotherapy drugs that work by triggering your immune system to attack cancer cells. However, this treatment has a fairly low success rate. Only 20% to 40% of patients respond to the treatment, and researchers began suspecting the gut microbiome might be the key to success or failure.

Indeed, as reported in Nature, a 2015 study found that while microbe-free mice failed to respond to treatment with checkpoint inhibitors, mice given Bacteroides fragilis fared much better. Other researchers have had similar findings, showing Bifidobacterium improves the effectiveness of cancer immunotherapy in lab animals — again by triggering a more robust response by specific anticancer immune cells.

As you might expect, antibiotic treatment has been found to worsen response to immunotherapy, likely because antibiotics indiscriminately kill all gut bacteria, thereby ridding your body of many really important immune helpers. Importantly, even cancer therapies that do not rely on the activation of your immune response typically fail unless you have the appropriate gut microbes. (source)

For example, certain chemotherapy agents actually rely on gut microbes to eradicate the tumor directly. In other instances, the microbes' influence on cancer is related to their ability to influence gene expression alter the stability of your genes.

Read More: Gut Microbiome May Be a Game Changer for Cancer Prevention

How do you find clinical trials that are testing immunotherapy?

To find clinical research studies that involve immunotherapy visit Find NCI-Supported Clinical Trials or call the Cancer Information Service, NCI’s contact center, at 1-800-4-CANCER (1-800-422-6237).

NCI’s list of cancer clinical trials includes all NCI-supported clinical trials that are taking place across the United States and Canada, including the NIH Clinical Center in Bethesda, MD.



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