Clinical trial: promising results for boosting the effects of radiotherapy

The goal behind the international phase III trial promoted by Nanobiotix* was to potentiate the action of radiotherapy by using hafnium nanoparticles, with Dr. Sylvie Bonvalot serving as the principal investigator and coordinator. And the goal was accomplished with flying colors based on the initial findings presented at the ESMO congress in Munich on 19 October.
Dr Sylvie Bonvalot

The use of hafnium nanoparticles in radiotherapy is new French technology developed by Nanobiotix, which draws on inert, inorganic nanoparticles especially designed to be activated by the x-rays used in radiotherapy. Once injected into the tumor, the nanoparticles accumulate in cancerous cells. Their physical properties mean they emit very high levels of energy upon exposure to x-rays, thus significantly amplifying the lethal doses injected into the tumor. This means radiotherapy effectiveness is bolstered without increasing the radiotherapy’s toxicity levels.

Presented by Dr. Bonvalot, the study was carried out on patients with soft tissue sarcomas, a rare type of tumor often diagnosed at an advanced stage. An initial I/II phase trial was led by Institut Curie and established the treatment’s innocuity, allowing researchers to identify the recommended dose.

To demonstrate the effectiveness of these nanoparticles compared to standard treatment, Dr. Bonvalot and her team along with 31 other centers scattered across a dozen European and Asian countries, included a group of 180 patients suffering from sarcomas who had given their consent to take part in this clinical trial. Half the group were given a single dose of nanoparticles injected into the tumor ahead of radiotherapy, while the other half were given standard treatment, meaning radiotherapy alone. At the end of the radiotherapy sessions, all patients underwent surgery to remove the tumor.

 “This was a highly innovative approach and the results show that the group of patients injected with a dose of nanoparticles before the standard radiotherapy sessions show a complete response rate that is twice as high as the group of patients who received standard radiotherapy-only treatment,” says Dr. Sylvie Bonvalot, head of the sarcoma surgery department at Institut Curie.

These findings pave the way for significant future developments. “This new technology improves the effects of radiotherapy without increasing toxicity, because the nanoparticles are only injected into the tumors themselves. The healthy tissue around the tumors are protected from the heightened effects of the radiotherapy,” explains Dr. Bonvalot. What’s more, the quality of exeresis (in which a tumor is surgically removed) carried out after a radiotherapy session is significantly improved. “Ultimately, injecting nanoparticles prior to radiotherapy treatment could improve patients’ chances of survival. This treatment will be particularly beneficial for tumors for which surgery is impossible or restricted”.

The technology is currently being investigated for application in other cancers.  Six other international trials are currently underway for liver, prostate, rectal, head and neck cancers. The head and neck cancer trial is being overseen by Institut Curie’s Prof. Christophe Le Tourneau.

*The Nanobiotix pharmaceutical laboratory is the promoter for this multicenter trial in which Institut Curie is the principal investigator.