Cancerous tumors that metastasize to the bones present a serious threat, often accompanied by significant pain. A recently developed drug shows promise in addressing both these challenges by interfering with the communication pathways between nerves and tumors. This novel approach hints at a future where cancer therapy could offer improved quality of life alongside extended survival.
“This signifies a promising new direction where a single cancer treatment can simultaneously enhance survival rates and improve patient well-being,” commented William Hwang, a researcher at Harvard University not involved in the study.
Between 65% and 80% of individuals with breast or prostate cancer that has spread to distant parts of the body develop bone metastases. As these skeletal tumors expand, they tend to activate nearby pain-sensing nerves.
Conventional treatments for bone tumors include radiotherapy, which uses X-rays to target malignant cells, and chemotherapy, employing potent drugs to attack rapidly dividing cells. These methods aim to reduce the size of bone growths. However, pain often persists because any surviving cancer cells continue to interact with nerve endings. Furthermore, traditional therapies can inadvertently damage healthy tissues, frequently necessitating the prolonged use of painkillers such as opioids, which carry the risk of addiction, according to Jiajia Xiang at Zhejiang University in China.
Nanodrug Design and Delivery
Xiang and his colleagues have engineered a “nanotherapy” composed of minuscule fatty capsules. These capsules encapsulate DNA that directs the production of gasdermin B, a protein that induces cell death by creating pores. The drug’s design specifically targets cancer cells, sparing healthy tissue. This is based on the observation that tumor cells often exhibit higher concentrations of reactive oxygen species compared to other cell types. The nanotherapy also incorporates OPSA, a compound that enhances the body’s natural immune response against cancer.
Preclinical Testing and Results
To evaluate the nanotherapy’s efficacy, researchers introduced breast cancer cells into the legs of laboratory mice. Once bone tumors had formed, the mice were administered one of three treatments: the complete nanotherapy, a modified nanotherapy with OPSA but without the gasdermin B gene, or a standard saline solution as a control. Each treatment was administered via tail injection every other day for a period of five days.
Two weeks post-treatment, the tumors in the group receiving the full nanotherapy had shrunk by an average of 94% compared to the control group. The simpler nanotherapy group saw tumor reduction of approximately 50%. After an additional two weeks, all mice treated with the complete nanotherapy remained alive. In contrast, only 60% of the mice receiving the simpler nanotherapy survived, and just 20% of the control group lived. The therapy successfully eradicated tumor cells directly and stimulated an anti-tumor immune response, Xiang confirmed.
Pain Reduction and Nerve Interaction
Unexpectedly, the researchers observed that mice treated with either form of the nanotherapy utilized their affected limbs significantly more than the control group. The complete nanotherapy group exhibited even greater improvement in limb function. This suggested that the nanotherapy might also alleviate the pain associated with bone tumors. Subsequent analysis of tumor tissue samples revealed that both nanotherapy treatments reduced the density of nerve cells, or neurons, within the cancerous growths.
This pain-reduction effect appears to stem from the nanotherapy’s ability to increase the cancer cells’ uptake of calcium ions. Sensory neurons require calcium ions to grow and transmit pain signals to the brain. “The hypothesis is that the cancer cells essentially act as a sponge, absorbing local calcium, thereby depleting the supply available to nearby sensory neurons,” explained Hwang. Further investigation is needed to precisely understand how the nanotherapy influences calcium uptake in cancer cells, which could lead to more refined targeting strategies for this potentially valuable pathway, Hwang added.
In a separate experiment, the team discovered that nerves surrounding the tumor actually contributed to its growth. This finding indicates that the nerve-related effects of the nanotherapy not only eased pain but also potentially slowed tumor progression, though the exact extent of this impact remains to be determined, Xiang noted.
Future Prospects and Clinical Translation
These findings align with the emerging understanding that modulating the nervous system could revolutionize cancer treatment, according to Hwang. However, he cautioned that translating discoveries from mice to humans is often challenging, partly due to differences in immune responses. Xiang expressed optimism about commencing human trials within the next five to ten years.
Journal reference: Science Advances DOI: 10.1126/sciadv.ady1292