New radiation therapy shows promise against tumors while preserving healthy tissue; understand

A new radiotherapy, created in Israel, offers promising results both in the main objective – eliminating tumors – and in preserving healthy cells, something that conventional radiotherapy can’t always do.

Called DaRT (Diffusing Alpha emitters Radiation Therapy), the technique is applied through a laser focused on eradicating cancer cells, sparing healthy tissues around the tumor. The treatment, which is available only to study groups, aims to contribute to the remission of cancer of the mouth, tongue, pancreas and breast cancer.

The research was developed at the Hadassah Medical Center in Jerusalem, Israel, and will be implemented in other hospitals, such as the Memorial Sloan Kettering Center and the Dana Farber-Cancer Institute, in the United States. Scientists seek partnerships in different countries.

“We would like to have the research instituted also in a Brazilian hospital, since the country has a great ethnic diversity and high rates of cancer”, says Professor Aron Popovtzer, the main person responsible for the studies of the technique.

The first results published in a scientific journal have been available in the International Journal of Radiation Oncology since 2018, but other studies have been carried out since then.

In the publication, the scientists describe what happened to 13 patients with radiation-resistant skin or head and neck cancer. At a median follow-up of five months, all tumors responded to treatment; nine tumors had a complete response, three tumors had a partial response, and one tumor was not successfully destroyed and was considered “under observation”. No major toxicity was noted.

Popovtzer explains exclusively to BBC News Brazil the action of DaRT in the human body and at what stage the therapy is.

How DaRT differs from other radiotherapy

The radiotherapy commonly used today has beta radiation or gamma radiation, which are performed with photons or electrons or even protons — unlike DaRT, which emits alpha particles.

Popovtzer clarifies that these standard radiations have the advantage of traveling over distances considered to be long (several centimeters), and can be radiated from outside the body to the middle of it.

“But among the problems with standard radiation is that they are oxygen-dependent, creating free radicals that often destroy only one of the cancer cell’s DNA strands, and unfortunately, that means the other can repair itself and therefore , will not necessarily kill the entire tumor.”

DaRT, explains the professor, can only travel a few millimeters, but it is very effective in the way it directly attacks the tumor.

“This radiation therapy has the power to ‘kill’ both strands of DNA and therefore the cells cannot regenerate. It is a new therapy because over the years, although we know that alpha particles have specific characteristics that make it very effective for radiation, we just didn’t know how to use it.”

The process of creating the new radiotherapy

15 years ago, professors Yona Keisari and Itzhak Kelson at Tel Aviv University discovered a way to use alpha radiation to destroy tumors.

Before that, as quoted by Professor Popovtzer, the potential of alpha radiation was known, but it could not reach more than about 50 microns (1/20th of a millimeter) inside human tissue. Treating a tumor of, say, 5 centimeters would require hundreds of thousands of short-range alpha-emitting sources — which would be theoretically impossible.

But the scientists found that when delivered via a specific isotope (atom) of the element radium, alpha radiation could travel up to 3 mm — enough to reach solid tumors — releasing atoms that diffuse inside a tumor and then emit their own radiation. alpha particles.

What are the results obtained so far?

“Our initial studies were done in mice and showed that DaRT had a greater power to destroy tumors when compared to standard radiation”, points out Popovtzer.

“And that led us to our first study in humans, the 2018 publication in the International Journal of Radiation Oncology.”

Since then, three other clinical publications, describing good results in eradicating tumors and protecting healthy tissues, have been completed.

“More recently we’ve been using new technology that’s based on computer software to make sure we cover all the tissue we need,” adds Popovtzer.

How DaRT radiation therapy is currently used

“What you do to use this technology is you put interstitial ‘seeds’ [dentro da pele] in the body, which is done with local anesthesia.”

“The advantage over brachytherapy [radioterapia interna usada em alguma parte específica do corpo], is that the seeds are very fine and therefore it is very easy to do this. And DaRT has a special tendency to enter only areas where it passes through deficient blood vessels, a characteristic present in tumors”, says the professor.

Now, the team of scientists is doing simultaneous studies to see how DaRT works in different types of cancer and with populations in different countries.

“For now, the benefited patients are only those who are part of the studies. The objective is to obtain the approval of the FDA (Food and Drug Administration) [a agência reguladora de saúde dos Estados Unidos]which decisions the government of Israel tends to embrace, so that we can institute the technology in different hospitals and, over time, hopefully, make it cheaper, as the cost is still high.”

This text was originally published on the BBC News Brazil website.