Tag: chemotherapy

Categories : Cancer COVIDTags :

COVID Vaccines less Effective in Patients Undergoing Chemotherapy

On By ModernMedia
Photo by National Cancer Institute on Unsplash

New research has found that patients undergoing active chemotherapy had a lower immune response to two doses of the COVID vaccine, although a third dose increased response.

“We wanted to make sure we understand the level of protection the COVID vaccines are offering our cancer patients, especially as restrictions were being eased and more contagious variants were starting to spread,” said Rachna Shroff, MD, MS, University of Arizona Health Sciences.

To find out, Dr Shroff and colleagues looked at 53 Cancer Center patients on immunosuppressive active cancer therapy, such as chemotherapy. They compared the immune response following the first and second dose of the Pfizer-BioNTech COVID vaccine with that of 50 healthy adults. 

After two vaccine doses, most of the cancer patients showed some immune response to the vaccine in that they had produced antibodies for SARS-CoV-2.

“We were pleasantly surprised,” said Deepta Bhattacharya, PhD, professor of immunobiology in the College of Medicine – Tucson. “We looked at antibodies, B cells and T cells, which make up the body’s defense system, and found the vaccine is likely to be at least partially protective for most people on chemotherapy.”

However, this  immune response was much lower than in healthy adults, and a few of the patients had no response to the COVID  vaccine. This translates to less protection against SARS-CoV-2, especially the now-dominant Delta variant.

Twenty patients returned for a third shot, which boosted the immune response for most. The overall group immune response after the third shot reached levels similar to those of people who were not on chemotherapy after two doses.

The results were published in Nature Medicine.

Source: University of Arizona Health Sciences

Categories : CancerTags :

How Cancer Cells Develop Resistance to Chemotherapy

On By ModernMedia
Source: National Cancer Institute on Unsplash

Researchers have found some answers as to why cancer cells can develop resistance to the cytotoxic drugs used in chemotherapy.

“We haven’t understood very much about how this resistance to chemotherapy develops and even less about how the microenvironment in cancer can affect the process,” said Kaisa Lehti, a professor at the Norwegian University of Science and Technology’s (NTNU) Department of Biomedical Laboratory Science.

Lehti has led this study into how cancerous tissues develop resistance to a particular form of chemotherapy, the results of which appear in Nature Communications.

If ovarian cancer is picked up early, almost all patients survive the first five years, while chances of survival are much worse if detected later. Finding effective treatment is therefore very important.

Platinum chemotherapy is one of the standard treatments for ovarian cancer, but cancer cells often develop resistance to this particular treatment. The reason lies in how the platinum-based cytotoxin itself can change the cancer cells and their environment.

Cytotoxin influences cancer cells and their environment
Lehti summed up the process: “The cytotoxin can change the way the cancer cells send and perceive signals and can modify the microenvironment around the cells.”

This change allows the cancer cells to withstand the damage caused by the cytotoxin—and can thus survive the chemotherapeutic attack. The researchers have found this key to the puzzle in a layer of tissue that often surrounds cancer cells.

“A fibrotic network of proteins, known as the extracellular matrix or ECM, surrounds the cancer cells, particularly the most aggressive ones,” said Lehti.

The fibrotic tissue, with the ECM network around the cancer cells, is mainly produced by normal connective tissue cells. But the cancer cells and connective tissue cells in the network can alter this tissue themselves.

“Previously, we haven’t known how the communication between the cancer cells and the extracellular matrix is affected by, or even itself influences, the development of cancer and its response to chemotherapy,” said Prof Lehti.

But it is now known that chemical and mechanical signals in the surrounding ECM tissue help cancer develop its ability to spread and to resist treatment.

“Certain signals from the ECM can critically change the cancer cells’ resistance to platinum-based cytotoxic drugs,” Prof Lehti explained.

In this way, the cytotoxin itself helps change both the microenvironment around the cancer cells and the ability of the cancer cells to sense their environment, and so resist the cytotoxin. By understanding this process, better therapies can be developed.

Source: MedicalXpress