Cancer treatment is often limited to prescribed chemotherapeutic agents or radiation therapy. They work by killing off malignant cells that would otherwise endlessly proliferate, much to the demise of the affected patient. These treatments for cancer are often time not tailored for each individual patient, but instead are based on previously attained success rates from clinical trials.
This is a problem, as chemotherapy can be devastating to a patient and even cause more complications.
Scientists from Portugal aim to mitigate this problem of not knowing what the most effective chemotherapeutic agent is for each case by using the larvae of the zebra fish.
Currently, if medical professionals want to know if a certain cancer treatment will be effective for a certain cancer, they have to use mouse studies. This involves transplanting human tumor cells into the mice, which they can then test the particular drug on. The problem is that the growth and proliferation of transplanted tumor cells can
This delay can prevent timely cancer treatment, which could be a matter of life and death.
This is exactly why the use of zebrafish larvae may turn out to be a good model for these types of chemotherapeutic testing, as it can take less than two weeks to find out what the best chemotherapy is for a particular case.
Previous studies have shown that mice and zebrafish react to treatments in the same way with the same drugs. This makes them a good model for human pharmacology.
“My main concern has been, for a long time, the fact that tumors change. Not only is it known that malignant tumors can be very heterogeneous—which means chemotherapy will not work against all its cells—but also that tumors evolve with time. This makes it all the more difficult to choose the right chemotherapy. In some cases, the efficacy rate of chemotherapies can be low, sometimes around 35%. This means that some patients risk-taking inadequate drugs that weaken them—and without a proper test, there is no way to know who will benefit and who won’t,” says Miguel Godinho Ferreira, a scientist at the Instituto Gulbenkian de Ciência (IGC) in Oeiras.
The tests carried out on zebrafish larvae models showed sufficient resolution to detect different treatment requirements, even in genetically similar tumors. Very small differences could be detected, helping to screen available therapeutic options to test their efficacy.
Preliminary studies have so far been positive, helping to identify the correct chemotherapy in four out of five cancer patients in a small study.
The next step is to hopefully set up a bigger study encompassing hundreds of patients to confirm the test’s predictive power. However, this will likely take a couple years to complete.