Immunotherapy is a godsend for cancer patients. Nonetheless, not all patients respond positively to the therapy. A recent study has a possible explanation as to why this happens.

A recent study conducted by Yale School of Medicine researchers, published within the journal Cancer Discovery, found the fault may lie within the DNA repair in tumors.

“We wanted to know why some patients respond higher than others to immunotherapy,” co-corresponding creator Ryan Chow, Yale’s Department of Genetics and the Systems Biology Institute, said, reported SciTechDaily.

In response to the outlet, studies have found only half of the patients with highly mutated colorectal and endometrial cancers will reply to immunotherapy.

The Yale team based their findings on the evaluation of a phase 2 study of 24 patients with endometrial cancer and the immunotherapy drug pembrolizumab.

The researchers pinned the explanation why immunotherapy doesn’t for some people on the failure of a process often known as “mismatch repair.” 

Errors within the DNA are common during cell division. There may be a special group of proteins that’s accountable for DNA correction. These proteins discover and proper DNA errors through mismatch repair. 

Now, an impediment to this editing process occurs in many differing types of cancer, resulting in high mutation levels.

The researchers opined that the breakdown within the repairing process can occur in two other ways. First, mutations can occur within the DNA repair machinery itself, which may result in the production of defective repair proteins. Second, the complete production of the DNA repair machinery can stop.

“An analogy could be a dysfunctional toy factory,” Chow said. “Possibly the factory makes broken toys that don’t work, or the factory has no personnel and stops producing toys altogether. Either way, kids won’t be blissful.”

Still, the researchers found that tumors with defective DNA repair proteins responded significantly higher to immunotherapy in comparison with those ones during which the production of DNA repair proteins had been halted.

The researchers said the differences between the 2 sorts of tumors could be attributed to the changes within the immune response that was in play against each of the tumors.

“In the case of immunotherapy, plainly the journey — on this case, the underlying reason behind mismatch repair deficiency — could also be just as necessary because the destination,” Chow commented.

“The revolutionary use of clinical trial data can guide our understanding of how immunotherapy manipulates the immune system and ultimately improve how we treat patients,” Dr. Eric Song, an ophthalmology resident at Yale, added.

One other study reported that sugary drinks may increase the danger of certain sorts of cancer.

“Results showed that consumption by men and ladies of greater than two SSB (Sugar-sweetened beverages) drinks a day versus individuals who never drank was not related to all-cancer mortality, but was related to increased risk of obesity-related cancers combined, which became null after adjustment for BMI,” the American Cancer Society noted in a news release.