A new experimental technique has proven successful against cancer. In the early phase of its first trial, the researchers have observed a 90% remission rate for patients with advanced leukemia who weren’t responding well to chemotherapy. These finding were first published in the Journal of Clinical Investigation on 25th April, 2016.
27 of the 29 patients responded remarkably positively to the treatment as they went into remission. Regarding this extraordinary result, lead author Dr David Maloney of the Fred Hutchinson Cancer Research Center said, “In early-phase trials, you’re continually learning. You don’t expect results like these from early-phase trials. That’s why these response rates are so extraordinary.”
What Is Immunotherapy And How Does It Work?
The technique is still in its early stages and is known as immunotherapy. This innovative form of cancer treatment fights off cancer by engineering the body’s immune system through a variety of different methods.
One of these methods called radioimmunotherapy involves using monoclonal antibodies to deliver radiation directly to cancer cells. Monoclonal antibodies are produced by a single clone of cells and contain similar antibodies. By attaching radiation molecules such as Zevalin and Bexxar, to monoclonal antibodies, low doses of radiation can be delivered to tumors leaving healthy cells alone.
Another method of immunotherapy is used to send cancer fighting drugs directly to tumors using monoclonal antibodies. One example of this technique is using Adcetris in the treatment of Hodgkin’s and non-Hodgkin’s lymphoma.
Monoclonal antibodies can also help in diagnosing hard to diagnose cancers such as prostate, rectal and ovarian cancer. Special cameras attached to the antibodies identify cancers by locating high radiation regions. Side effects of using monocle antibody treatment are usually similar to an allergic reaction, including watery eyes, sneezing, fever and rashes.
This study uses immunotherapy to genetically engineer T-cells, a type of lymphocyte and one of the immune system’s defense mechanisms, to express chimeric antigen receptor (CAR) that can target almost any tumor. Scientists extract T-cells out of the patients, change their biological chemistry using a virus, reproduce them and release them back in the body. If these CAR T-cells are accepted by the immune system, they can help eliminate tumor cells that possess whichever specific antigen the researchers wanted them to target.
Maloney and his team of researchers developed CAR T-cells that targeted the B-lymphocyte antigen CD19, an antigen protein found in white blood cells. The team injected the cells into 30 patients with B cell acute lymphoblastic leukemia, an advanced and complex form of leukemia. T-cells are of two types, helper and killer, and work together to boost the immune system. Maloney’s team made sure that they injected the patients with equal amounts of both types of T-cells. It was the first clinical trial to infuse patients with equal mixture of both types of T-cells. By doing this, the team hoped they would make the treatment more effective and improve the patient’s immune system. The team further explored the results produced by combining the T-cells in different ratios.
Dr Cameron Turtle, lead author of the study, said that patients should be closely observed to see how they react to the treatment they receive, and all of the dosage’s possible effects need to be known beforehand to provide a more accurate and effective treatment.
Limitations Of The Research
Even though the findings are quite significant and revolutionary, the researchers are far from finding the ideal cure, for the time being. Nearly all the patients suffered from cytokine release syndrome, a type of non-infective fever that produces an inflammatory response due to the high amounts of cytokines being released by the immune system in response to the increased amount of anti T-cells. Two patients died from the treatment, one immediately after receiving the dose, and one after 122 days. So the researchers decided to lower the dosage for future treatments, which prevented further complications.
The Leukemia did momentarily go into remission in the case of 27 patients, but it eventually returned with a vengeance for several patients. At least two of the patients developed cancer that did not contain any CD19 antigens, rendering this method of treatment useless. Patients who relapsed to the treatment, their immune systems became more resistive to additional infusion of the CAR T-cells.
These setbacks can be detrimental to the fight against cancer but Turtle and rest of the researcher remain optimistic. “This is just the beginning. It sounds fantastic to say that we get over 90 percent remissions, but there’s so much more work to do to make sure they’re durable remissions, to work out who’s going to benefit the most, and extend this work to other diseases,” said Dr Turtle.
There were many limitations to the study. One of the limitations being that the trial was done on a small test group. Another limitation the researchers faced was that they couldn’t provide sufficient evidence of the therapy’s impact against cancer.