In 1989, two undergraduate students at the Free University
of Brussels were asked to test frozen blood serum from camels, and stumbled on
a previously unknown kind of antibody. It was a miniaturized version of a human
antibody, made up only of two heavy protein chains, rather than two light and
two heavy chains. As they
eventually reported, the antibodies’ presence was confirmed not only in
camels, but also in llamas and alpacas.
Fast forward 30 years. In the journal PNAS this week, researchers at Boston Children’s Hospital and MIT show that these mini-antibodies, shrunk further to create so-called nanobodies, may help solve a problem in the cancer field: making CAR T-cell therapies work in solid tumors.
Their plan is to optimize the ability for CAR T-cell therapies, which use a patient’s genetically modified T cells to combat cancer, to more specifically kill tumor cells without setting off an immune response “storm” known as cytokine release syndrome. The key ingredient is a unique small molecule that greatly enhances the specificity of the tumor targeting component of the therapy. …
A novel screening method using CRISPR-Cas9 genome editing technology has revealed new drug targets that could potentially enhance the effectiveness of PD-1 checkpoint inhibitors, a promising new class of cancer immunotherapy.
In March 2016, Ollie, a therapy dog at Boston Children’s Hospital, paid a bedside visit to 7-year-old Carter Mock. The pug and the boy had something in common: Both had lost limbs to the bone cancer osteosarcoma. Ollie’s left front leg had been amputated at the shoulder, while Carter had just had a new knee fashioned from his ankle in a procedure called rotationplasty.
Biologically, the osteosarcoma that dogs develop is remarkably similar to osteosarcoma in children and youths. The tumors develop primarily in the long bones, and the spread of tumor cells to the lungs represents the most significant threat and challenge. Similar chemotherapy agents are used in both dogs and human patients to kill residual cancer cells. Researchers are now mining these similarities in a quest for new treatments to benefit pets and people alike. …
Recent clinical trials for patients with advanced melanoma have found that a new class of drugs—anti-PD-1 antibodies—can elicit an unprecedented response rate. In the last year, the FDA gave accelerated approval to two anti-PD-1 antibodies, nivolumab and pembrolizumab, for patients with advanced melanoma (including Jimmy Carter) who are no longer responding to other drugs. And there’s growing evidence that this class of drugs may be effective in treating other forms of cancer.
Anti-PD-1 antibodies target a receptor on activated T cells, known as the programmed cell death 1 (PD-1) receptor. Tumor cells stimulate this inhibitory receptor to dodge immune attack, whereas anti-PD-1 antibodies block the same pathway, “waking up” the immune cells so they can attack the cancer. The drugs have been hailed as one of the first cancer immunotherapy success stories. …
One of the immune system’s basic jobs is to tell “self” from “non-self.” Our cells carry markers that the immune system uses to recognize them as being part of us. Cells that don’t carry those markers—like bacteria and other pathogens—therefore don’t belong.
Cancer cells, however, fall into a gray area. They’re non-self, yet they also bear markers that connote self-ness—one of the reasons the immune system has a hard time “seeing” and reacting to cancer.
Can we focus the immune system’s spotlight on cancer cells? The provisional answer is yes. Research on cancer immunotherapy—treatments that spur an immune response against cancer cells—has boomed in recent years. (The journal Science recognized cancer immunotherapy as its Breakthrough of the Year in 2013.)
Not long ago I received a wonderful email from “Sam,” an 18-year-old young man with peanut allergy. He was participating in a clinical trial of oral immunotherapy (OIT) being carried out by colleagues here at Boston Children’s Hospital.
In OIT, patients receive initially minute doses of the food to which they are allergic. Then, over many weeks, they ingest increasing amounts, under close medical monitoring at the hospital.
OIT’s goal is to get patients to tolerate previously allergenic foods by inducing their bodies to produce Treg cells, or regulatory T cells. These are the master controllers of our immune responses, and their actions include suppressing allergic responses to foods. Food ingestion, as in OIT, will eventually induce food-specific Treg cells, but it can be a long and cumbersome process. For Sam, ingesting escalating doses of peanuts proved difficult: His email described frequent reactions ranging from stomachaches and itchiness to difficulty breathing. …
If there’s anything that tumors are good at, it’s hiding themselves. Not from things like MRIs or CT scans, mind you, but from the immune system. Since a tumor grows from what were at one time normal, healthy cells it’s still “self,” still one of the tissues that makes you you.
Researchers have worked for years on cancer vaccines aimed at getting the immune system to wake up to the presence of a tumor and turn on it. With a Phase 1 safety trial , Kieran and his colleagues, including Children’s neurosurgical oncologist Lily Goumnerova, are evaluating a different strategy for patients with hard-to-treat brain tumors called malignant gliomas: They’re giving the tumors a cold. …