Modifications in cell-free tumour DNA following intra-tumoural bromelain and N- acetylcysteine in pseudomyxoma peritonei: a post-hoc analysis of the BromAc trial
This post-hoc analysis of the BromAc trial demonstrates that intratumoural administration of bromelain and N-acetylcysteine in pseudomyxoma peritonei patients leads to a measurable reduction in KRAS/GNAS mutant allele fractions, which correlates with radiological tumour response and suggests potential utility as a molecular indicator for treatment monitoring.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
Inside the human body, some cancers grow slowly and quietly, filling the abdominal cavity with a thick, jelly-like substance called mucin rather than forming a solid lump. This condition, known as pseudomyxoma peritonei, is rare and difficult to treat. While surgeons can often remove the bulk of the disease, the jelly-like material frequently returns, and standard chemotherapy drugs usually cannot reach or kill the cells hidden within it. Because the cancer cells are trapped inside this thick mucus, doctors have been searching for ways to break down the barrier and shrink the tumor from the inside out. One promising approach involves injecting a mixture of two substances directly into the tumor mass to liquefy the mucus, allowing it to be drained away and reducing the pressure on the patient's organs.
A team of researchers recently investigated whether this liquefaction treatment also changes the genetic makeup of the cancer cells themselves. They focused on two specific genes, KRAS and GNAS, which are known to be mutated, or altered, in many cases of this disease. These mutations act like a permanent "on" switch for the cancer, driving its growth. The scientists wanted to know if the treatment, which uses an enzyme from pineapples called bromelain and a compound called N-acetylcysteine, could not only shrink the visible tumor but also lower the amount of these mutated genes circulating in the mucus. If the treatment works, the number of these genetic errors should drop, offering a new way to measure success beyond just looking at scans.
To find the answer, the researchers studied patients who had received this direct injection therapy. They collected samples of the thick mucus from the patients' tumors before the treatment began and again after the injections were given. Using a highly sensitive method that counts individual DNA molecules, they measured how much of the mutated KRAS and GNAS genes were present in each sample. They also looked at a separate group of patients who had undergone surgery to see how common these mutations were in the first place. The results confirmed that these genetic errors are very common in this type of cancer, appearing in the vast majority of the samples they tested.
When the team analyzed the patients who received the injection treatment, they found a clear pattern. In most of the tumor masses treated, the amount of mutated KRAS and GNAS genes dropped significantly after the therapy. This reduction happened in more than four out of every five tumor masses examined. The researchers compared this genetic change to the physical changes seen on medical scans. They found that when the genetic mutations decreased, the tumor volume usually decreased as well. Specifically, if the amount of the mutated gene went down, there was a strong chance that the tumor had shrunk on the scan, both one month and one year after the treatment.
The study suggests that measuring these genetic changes in the mucus could serve as a reliable early warning system for doctors. Instead of waiting months to see if a tumor is shrinking on a scan, a simple drop in the mutated genes might indicate that the treatment is working much sooner. While the researchers caution that their group of patients was small and that more studies are needed to confirm these findings, the connection between the genetic drop and the physical shrinkage was consistent. This work offers a new perspective on how to monitor difficult-to-treat cancers, showing that breaking down the tumor's physical structure can also reduce its genetic burden, potentially opening the door for better treatment strategies in the future.
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