Cu2 WS4 -PEG Nanozyme as Multifunctional Sensitizers for Enhancing Immuno-Radiotherapy by Inducing Ferroptosis

Unavoidable damage to normal tissues and tumor microenvironment (TME) resistance make it challenging to eradicate breast carcinoma through radiotherapy. Therefore, it is urgent to develop radiotherapy sensitizers that can effectively reduce radiation doses and reverse the suppressive TME. Here, a novel biomimetic PEGylated Cu2 WS4 nanozyme (CWP) with multiple enzymatic activities is synthesized by the sacrificing template method to have physical radiosensitization and biocatalyzer-responsive effects on the TME. Experiment results show that CWP can improve the damage efficiency of radiotherapy on breast cancer cell 4T1 through its large X-ray attenuation coefficient of tungsten and nucleus-penetrating capacity. CWP also exhibit strong Fenton-like reactions that produced abundant ROS and GSH oxidase-like activity decreasing GSH. This destruction of redox balance further promotes the effectiveness of radiotherapy. Transcriptome sequencing reveals that CWP induced ferroptosis by regulating the KEAP1/NRF2/HMOX1/GPX4 molecules. Therefore, owing to its multiple enzymatic activities, high-atomic W elements, nucleus-penetrating, and ferroptosis-inducing capacities, CWP effectively improves the efficiency of radiotherapy for breast carcinoma in vitro and in vivo. Furthermore, CWP-mediated radiosensitization can trigger immunogenic cell death (ICD) to improve the anti-PD-L1 treatments to inhibit the growth of primary and distant tumors effectively. These results indicate that CWP is a multifunctional nano-sensitizers for radiotherapy and immunotherapy.

[Immuno-radiotherapy: A review of the rationale, recent clinical developments and future prospects]

Thanks to the success of checkpoint inhibitors, immunotherapy now plays a major role in the management of a large number of solid tumors, while the number of indications continues to grow and new combinations could, in the near future, further modify treatment standards. However, the response rates of immunotherapies as monotherapy are modest and their use is increasingly considered in combination with other cancer treatments (chemotherapy, surgery, radiotherapy or certain targeted therapies). Combinations with radiotherapy seem particularly attractive because there is a strong experimental rationale linking part of the efficacy of ionizing radiation to an induced stimulation of both of the innate and adaptive response. Many early phases and a number of large randomized combination trials have published efficacy and safety results, while important trials are still ongoing and will provide answers in the near future. This short review recalls the experimental biological rationale for immuno-radiotherapy and highlights some of the fundamental directions being explored, then presents the clinical efficacy and safety results available to date, those expected in the near future, and finally outlines the outlook in this rapidly evolving field.

Combination immunotherapy and radiotherapy causes an abscopal treatment response in a mouse model of castration resistant prostate cancer

BACKGROUND

Prostate cancer is poorly responsive to immune checkpoint inhibition, yet a combination with radiotherapy may enhance the immune response. In this study, we combined radiotherapy with immune checkpoint inhibition (iRT) in a castration-resistant prostate cancer (CRPC) preclinical model.

METHODS

Two Myc-CaP tumor grafts were established in each castrated FVB mouse. Anti-PD-1 or anti-PD-L1 antibodies were given and one graft was irradiated 20 Gy in 2 fractions.

RESULTS

In CRPC, a significant increase in survival was found for radiation treatment combined with either anti-PD-1 or anti-PD-L1 compared to monotherapy. The median survival for anti-PD-L1 alone was 13 days compared to 30 days for iRT (p = 0.0003), and for anti-PD-1 alone was 21 days compared to 36 days for iRT (p = 0.0009). Additional treatment with anti-CD8 antibody blocked the survival effect. An abscopal treatment effect was observed for iRT in which the unirradiated graft responded similarly to the irradiated graft in the same mouse. At 21 days, the mean graft volume for anti-PD-1 alone was 2094 mm³ compared to iRT irradiated grafts 726 mm³ (p = 0.04) and unirradiated grafts 343 mm³ (p = 0.0066). At 17 days, the mean graft volume for anti-PD-L1 alone was 1754 mm³ compared to iRT irradiated grafts 284 mm³ (p = 0.04) and unirradiated grafts 556 mm³ (p = 0.21). Flow cytometry and immunohistochemistry identified CD8+ immune cell populations altered by combination treatment in grafts harvested at the peak effect of immunotherapy, 2-3 weeks after starting treatment.

CONCLUSIONS

These data provide preclinical evidence for the use of iRT targeting PD-1 and PD-L1 in the treatment of CRPC. Immune checkpoint inhibition combined with radiotherapy treats CPRC with significant increases in median survival compared to drug alone: 70% longer for anti-PD-1 and 130% for anti-PD-L1, and with an abscopal treatment effect.

PRECIS

Castration-resistant prostate cancer in a wild-type mouse model is successfully treated by X-ray radiotherapy combined with PD-1 or PD-L1 immune checkpoint inhibition, demonstrating significantly increased median overall survival and robust local and abscopal treatment responses, in part mediated by CD8 T-cells.