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Friday, December 30, 2016

Cell Therapy (Setting the Body’s ‘Own Killer T Cells Loose on Cancer)

Cellular Immune Therapy of Cancer

Most of the above approaches have the limitation that they require delivery of a "corrective" gene to every cancer cell, a demanding task. An alternative is to harness the immune system, which may have an ability to actively seek out cancer cells. In healthy adults, the immune system recognizes and kills precancerous cells as well early cancer cells, but cancer progression is an evolutionary process and results in large part from an immune-evasive adaptive response to the cancer microenvironment affecting both the afferent and efferent arms of the immune response arc. This results in inhibition of the ability of a patient’s immune system to target and eradicate the tumor cells. To this end, investigators are developing and testing several cell therapy strategies to correct impairment of the host-cancer immune interaction and as a consequence, to improve the immune system’s ability to eliminate cancer.
Cell therapy for cancer refers to one or more of 3 different approaches: (i) therapy with cells that give rise to a new immune system which may be better able to recognize and kill tumor cells through the infusion of hematopoietic stem cells derived from either umbilical cord blood, peripheral blood, or bone marrow cells, (ii) therapy with immune cells such as dendritic cells which are designed to activate the patient’s own resident immune cells (e.g. T cells) to kill tumor cells, and (iii) direct infusion of immune cells such as T cells and NK cells which are prepared to find, recognize, and kill cancer cells directly. In all three cases, therapeutic cells are harvested and prepared in the laboratory prior to infusion into the patient. Immune cells including dendritic cells, T cells, and NK cells, can be selected for desired properties and grown to high numbers in the laboratory prior to infusion. Challenges with these cellular therapies include the ability of investigators to generate sufficient function and number of cells for therapy.  
Clinical trials of cell therapy for many different cancers are currently ongoing. More recently, scientists have developed novel cancer therapies by combining both gene and cell therapies. Specifically, investigators have developed genes which encode for artificial receptors, which, when expressed by immune cells, allow these cells to specifically recognize cancer cells thereby increasing the ability of these gene modified immune cells to kill cancer cells in the patient. One example of this approach, which is currently being studied at multiple centers, is the gene transfer of a class of novel artificial receptors called “chimeric antigen receptors” or CARs for short, into a patient’s own immune cells, typically T cells. Investigators believe that this approach may hold promise in the future for patients many different types of cancer. To this end, multiple pilot clinical trials for a variety of cancer types using T cells genetically modified to express tumor specific CARs are ongoing, some of which are showing promising results.
After a long, intense pursuit, researchers are close to
bringing to market a daring new treatment: cell therapy
that turbocharges the immune system to fight cancer.
The patient’s T-cells, the soldiers of the immune system, are extracted from the patient’s blood, then genetically engineered to recognize and destroy cancer
The redesigned cells are multiplied in the laboratory, and millions or billions of them are put back into the patient’s bloodstream, set loose like a vast army of tumor assassins.
The killer cells are genetically engineered to produce a complex protein, an amalgam of pieces from different parts of the immune system that is unlike anything seen before.…/cancer-cell-therapy-immune-system.……/cells-dripped-into-brain-help-man-…

When 5-year-old Emily Whitehead was first diagnosed with acute lymphoblastic leukemia (ALL), the most common pediatric cancer, her parents were optimistic – the cure rate for ALL can be as high as 85 percent. “We felt pretty hopeful at that point,” says her mom, Kari.
But the chemotherapy treatments were hard on Emily. She suffered from constant pain and nausea and developed a life-threatening infection in her legs. Her cancer went into remission twice, but each time it returned.
Soon, it became clear that there was not much more Emily’s doctors could do.
That’s when her parents brought her to The Children’s Hospital of Philadelphia (CHOP).

A Dramatic Recovery

The days immediately after Emily received the T cell therapy were harrowing. She spent over a week in CHOP’s Pediatric Intensive Care Unit, on a ventilator and heavily sedated. Her symptoms were an indication that the T cells were hard at work in her body. But her body’s reaction to the cells was so intense she nearly died.
Then her medical team made another breakthrough. One night, after they found abnormal levels of a certain protein in her blood, they were able to identify a medication – one not typically used in cancer patients – that they believed would block the effects of the protein.
The team administered the drug to Emily, with dramatic results. “The ICU doctor told me that he had never seen a patient that sick get better that quickly,” says Grupp.
Over the next weeks, Emily completely recovered from the illness that resulted from the T cell therapy – and tests soon revealed that her leukemia was in remission.
Emily went home from the hospital on June 1. And thus far, she remains in remission.

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