Immunotherapy Effective Against Advanced Leukemia

The next generation of cancer treatments will be targeted approaches that destroy only cancer cells, with few or no side-effects. Given the results of the past decade of work, it looks likely that a majority of these treatments will be immune therapies, in which a patient's immune cells are engineered or trained to identify and attack the cancer. Clinical trials for a few such therapies are ongoing, mixed in with established treatment options. This is an example one of the more effective applications to date:

The largest clinical study ever conducted to date of patients with advanced leukemia found that 88 percent achieved complete remissions after being treated with genetically modified versions of their own immune cells. "These extraordinary results demonstrate that cell therapy is a powerful treatment for patients who have exhausted all conventional therapies. Our initial findings have held up in a larger cohort of patients, and we are already looking at new clinical studies to advance this novel therapeutic approach in fighting cancer."

Adult B cell acute lymphoblastic leukemia (B-ALL), a type of blood cancer that develops in B cells, is difficult to treat because the majority of patients relapse. Patients with relapsed B-ALL have few treatment options; only 30 percent respond to salvage chemotherapy. Without a successful bone marrow transplant, few have any hope of long-term survival.

In the current study, 16 patients with relapsed B-ALL were given an infusion of their own genetically modified immune cells, called T cells. The cells were "reeducated" to recognize and destroy cancer cells that contain the protein CD19. While the overall complete response rate for all patients was 88 percent, even those with detectable disease prior to treatment had a complete response rate of 78 percent, far exceeding the complete response rate of salvage chemotherapy alone.

In the current study, seven of the 16 patients (44 percent) were able to successfully undergo bone marrow transplantation - the standard of care and the only curative option for B-ALL patients - following treatment. Three patients were ineligible due to failure to achieve a complete remission, three were ineligible due to preexisting medical conditions, two declined, and one is still being evaluated for a potential bone marrow transplant. Historically, only 5 percent of patients with relapsed B-ALL have been able to transition to bone marrow transplantation.



If 88% of patients achieved complete remission, why did they then have to undergo a bone marrow transplant? If the cancer was gone why would they need this?

Posted by: Jim at February 20th, 2014 3:05 PM

@Jim: It makes more sense if you consider the way that researchers approach this. There is an existing set of standard operating procedures for treating this leukemia, and the immune therapy is being used to replace only one of those steps (the last-hope chemotherapy). Best practice is still to continue with what is known to work in the other steps. The Wikipedia entry is informative:

On the one hand this is general conservatism of the scientific type, the incremental approach. On the other hand once procedures are sufficiently established institutions open themselves up to malpractice claims by not following them. You'll see this in a range of areas in medicine (first hand, eventually, sadly) where there are very standard, established approaches for a particular condition, and any subtlety or variation that might be adopted in a more flexible system is eliminated by the actions of medical institutions and the threat of lawsuits.

Posted by: Reason at February 20th, 2014 7:24 PM

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