How NBTXR3 Amplifies Radiotherapy

In an interview with Targeted Oncology, Colette Shen, MD, PhD, assistant professor at the University of North Carolina (UNC) Chapel Hill and radiation oncologist at the UNC Lineberger Comprehensive Cancer Center, explains the mechanisms of action of the novel radioenhancer NBTXR3 (JNJ-1900) that demonstrated safety and preliminary efficacy in patients with recurrent or metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) in the phase 1 Study 1100 (NCT03589339).

Watch the first part of Dr Shen’s interview.

NBTXR3 is a suspension of inert hafnium oxide nanoparticles.¹ Upon injection into the tumor, the nanoparticles accumulate in the tumor cells but remain inactive until exposed to radiation.

In standard radiotherapy, the radiation interacts with water in tissue, creating electrons or reactive oxygen species that indirectly damage DNA and tumor cells. With NBTXR3 in the tumor cells, the interaction between radiation and the nanoparticles generates a significantly greater number of electrons.

“When these nanoparticles are in the tumors that we then give radiation to, the radiation interacts with those nanoparticles in a way that [generates approximately] 9 to 10 times more electrons or reactive oxygen species with that interaction. So, you can think of the radiation potentially being up to 9 to 10 times stronger immediately around where the nanoparticles are,” explained Shen in the interview.

This reaction results in a stronger, more targeted destruction of tumor cells and DNA without damaging surrounding structures.

Read the full interview here.

REFERENCE:

1. NCI Drug Dictionary- hafnium oxide-containing nanoparticles NBTXR3. National Cancer Institute. 2025. Accessed October 11, 2025. https://tinyurl.com/bdzc2uh2