Nanoparticles and Radiotherapy: A Winning Combination in the Fight Against Cancer
Once injected into the tumor, the NBTXR3 nanoparticles developed by Nanobiotix multiply the effects of the radiation without impacting the neighboring tissue. They therefore allow for more extensive use of radiotherapy, which is often limited due to the inability to increase the dose or the proximity of sensitive organs.
The efficacy of NBTXR3 nanoparticles has now been proved in a recent phase II/III trial in patients with soft tissue sarcomas. This is the final stage prior to their release onto the market. Soft tissue sarcomas develop in the supportive tissues that link the various structures of the body or make up the walls of organs. They can therefore occur in many different parts of the body. “The standard treatment for these tumors at the early stage is surgery,” explains Dr. Sylvie Bonvalot, a world-renowned specialist in the very specific surgery of sarcomas. “This surgery can be very complex: the tumors to be removed are generally very large, since they have been there for a long time without producing symptoms. When the tumors develop in the abdomen, it is sometimes even necessary to remove the neighboring organs to prevent relapses.” To limit the extent of the surgery, radiotherapy may be used before surgery to reduce the size of the tumor and sterilize the surrounding area. However, this treatment is limited by the proximity of other organs, which means that the radiation dose cannot be increased and thus its effectiveness is also limited.
Multiplying the Effects of Radiotherapy
NBTXR3 offers a new method of action for treating not just this form of cancer but, more widely, numerous other cancers, since it physically destroys cancer cells when activated by radiotherapy. What’s more, it is highly effective: two times as many patients (16.1% vs. 7.9%) experienced a pathological complete response—defined as the rate of patients presenting less than 5% residual viable cancer cells in the tumor after treatment—with NBTXR3 compared to the control arm.
“Data are exceptional and show without any doubt an improvement of radiation therapy impact with a significant number of complete response. NBTXR3 can bring real benefit to patients and it can change the standard of care. This innovation will play a role in many other indications and particularly where radiotherapy is used alone.,” the surgeon explains.
Another of the trial’s endpoints was resection margins status, which assesses the quality of the surgery. The primary objective is to achieve “clean” margins, meaning that no more cancer cells can be found around the edges where the tumor was removed. This rate increased by 20%. The absence of cancer cells at the tumor margins affects the likelihood of relapse as well as patient survival rates.
The outlook for other cancers is also promising. As Dr. Bonvalot explains, “We have already shown a superior response with NBTXR3 at an equivalent dose. Since sarcomas are not very radiosensitive, we can expect major advances for other cancers.” The nanoparticles are already being assessed on other tumor locations, such as the prostate and ENT tumors. Institut Curie is once again playing a key role in these trials, with Prof. Christophe Le Tourneau acting as principal investigator.