Biology subjects

Setianegara, J.

Publications and source records attributed to Setianegara, J..

3 recordsLinked to original sources

bioRxiv2026

Proton FLASH radiotherapy enhances control of triple-negative breast cancer through STING-IRF3 and CD8+ T-cell immunity

FLASH radiotherapy delivers radiation at ultra-high dose rates and has been demonstrated to spare normal tissue compared to standard radiotherapy, but it is not known if dose rate also modifies tumor response. Here we compare a single 13.5 Gy fraction of proton irradiation delivered at FLASH (F-PRT) or Standard (S-PRT) dose rate in immunocompetent C57BL/6 mice bearing EO771 or AT3 triple-negative mammary tumors. At this identical physical dose, F-PRT delays tumor growth more than S-PRT at both heterotopic and orthotopic sites. The effect is largest in EO771, where F-PRT also prolongs tumor-volume endpoint-free survival and reduces the emergence of lung metastases relative to S-PRT. F-PRT induces earlier intratumoral STING expression and IRF3 nuclear translocation, higher type I interferon levels and greater CD8+ T-cell infiltration. CD8+ T-cell depletion or systemic STING inhibition abolishes the F-PRT advantage. Combined with anti-PD-1 and agonistic anti-CD40, both modalities produce durable complete responses that reject contralateral rechallenge, but F-PRT limits tumor progression before response and accelerates regression. FLASH proton radiotherapy not only improves normal-tissue tolerance, but also antitumor immunity, suggesting that ultra-high dose rate could widen the therapeutic window from both sides.

cancer biology↗

bioRxiv2026

Fractionated proton and photon FLASH irradiation mitigates radiation-induced lymphopenia through kinetic sparing of circulating lymphocytes

Background and purpose: Radiation-induced lymphopenia is associated with adverse outcomes in thoracic malignancies. FLASH radiotherapy delivers radiation over a timescale of hundreds of milliseconds, potentially reducing the fraction of irradiated circulating lymphocytes. In this study, we investigated whether FLASH mitigates lymphopenia after thoracic irradiation delivered with protons or photons. Materials and methods: C57BL/6 mice received three 13.5-Gy whole-heart fractions at 48-hour intervals using FLASH or standard dose-rate proton irradiation at the University of Pennsylvania (n=15), with photon validation at Queen's University Belfast (n=72). Leukocytes and CD4 T cells, CD8 T cells, B cells, and NK cells were quantified by hemocytometer and flow cytometry. A continuous-time Markov model simulated lymphocyte trafficking, dose accumulation, and post-irradiation recovery. Results: FLASH attenuated leukocyte depletion across both proton and photon irradiation modalities. In the proton cohort, white blood cell counts were significantly higher after FLASH at D1, D3, D7, and D14; CD4 T cells and NK cells were preserved through D14, while CD8 T cell sparing persisted through D21. Photon FLASH preserved CD45 leukocytes at D1, D3, D7, and D21, with sustained CD8 sparing at D21. Modeling showed that FLASH shifted the lymphocyte dose distribution toward lower exposures, increasing the proportion of lymphocytes receiving <1 Gy from 2.4% to 16.4%, and reduced the proportion of lymphocytes repeatedly irradiated across all three fractions from 36.3% at standard dose rate to 9.18%, despite similar median cumulative doses. The spleen contributed substantially to cumulative lymphocyte dose, and marrow-entering lymphocytes displayed a more high-dose-enriched distribution after FLASH irradiation. Conclusion: FLASH consistently mitigated radiation-induced lymphopenia for proton and photon modalities, with durable CD8 T cell preservation. These findings support a kinetic mechanism and provide a rationale for combining FLASH radiotherapy with immune-sparing planning and immunotherapy.

cell biology↗

bioRxiv2025

Proton FLASH Exposure Preserves Gut Commensal Microbiomes and Spares Intestinal Stem Cells

Emerging evidence shows Proton FLASH radiotherapy can spare normal tissues while maintaining anti-tumor efficacy. However, its impact on intestinal stem cell (ISC) populations and the gut microbiome remains unclear. This is critical, as the gut microbiome influences ISC radiosensitivity. In a mouse model of radiation-induced gastrointestinal syndrome, FLASH-irradiated mice exhibited better survival and less crypt-villus damage compared to mice exposed to conventional proton irradiation. Using scRNA-sequencing, we demonstrated that proton FLASH exposure using pulsed pencil beam scanning spares two distinct ISC populations--Lgr5+ CBCs and a Clu+, Mif+, Fabp2+, Anxa2+ revival stem cell (revSC) population--by modulating oxidative stress and cell cycle progression. Analysis of alpha and beta diversity demonstrated that FLASH modulates gut microbiota composition without compromising overall species richness. Notably, FLASH-irradiated mice had higher abundances of Alistipes sp. and Akkermensia sp., both known for protective effects on ISCs and the intestinal mucosa. The critical role of microbiome in FLASH-mediated sparing effect against radiation toxicity was further confirmed by fecal microbiota transplantation, where FLASH-donor microbiota demonstrated reduced lethality in recipients exposed to proton irradiation with conventional dose rate. Our findings highlight the crucial role of the microbiome in the FLASH-mediated sparing of the mucosal epithelium.

bioengineering↗