Disertasi

Efek Bystander dan Abscopal pada Spatially Fractionated Grid Radiotherapy (SFGRT): Studi Menggunakan Babi Domestik (Sus scrofa domesticus) dengan Karsinoma Sel Hati = Bystander and Abscopal Effects in Spatially Fractionated Grid Radiotherapy: A Study Using Domestic Swine (Sus scrofa domesticus) with Hepatocellular Carcinoma.

Latar Belakang: Spatially Fractionated Grid Radiotherapy (SFGRT) dilaporkan berperan dalam tatalaksana tumor berukuran besar, termasuk karsinoma sel hati (KSH). Namun, pengetahuan mekanisme kerja SFGRT masih terbatas. Studi hewan coba besar dapat bermanfaat untuk menambah bukti ilmiah, dimana studi ini merupakan studi pertama induksi KSH dengan N-Diethylnitrosamine (DENA) pada babi domestik. Penelitian ini bertujuan untuk mengevaluasi pola kematian sel, efek bystander, efek abscopal, serta respons imun dari SFGRT pada hewan coba besar dengan KSH. Metode: Uji eksperimental dilakukan pada 10 babi domestik (Sus scrofa domesticus) yang diinduksi dengan injeksi DENA 15 mg/kgBB dan fenobarbital (PB) 4 mg/kgBB. Subjek dievaluasi secara periodik menggunakan USG, CT scan, analisa darah. Diagnosis KSH ditegakkan dengan pemeriksaan imaging dan histopatologi. Subjek dirandomisasi sebagai kontrol negatif, kontrol positif, penerima intervensi SFGRT 1x20 Gy dosis tunggal, atau penerima intervensi radiasi lengkap SFGRT 1x20 Gy + Stereotactic Body Radiotherapy (SBRT) 3x8 Gy. Pemeriksaan flowcytometry Annexin dilakukan untuk melihat pola kematian sel, dan biomarker TNF- a, IFN-ɣ, FOXP3 untuk melihat respons jaringan tumor dan jaringan hati di dalam dan di luar area radiasi. Hasil: Karsinogenesis berhasil pada seluruh subjek setelah 15-22 bulan induksi, berupa KSH dan angiosarkoma hepatik. Peningkatan FOXP3 diamati pada subjek yang mengalami keganasan dibandingkan kontrol negatif, sementara TNF- a dan IFN-ɣ mengalami penurunan. Pemeriksaan Annexin menunjukkan rendahnya jumlah sel viabel signifikan pada perlakuan radiasi lengkap SFGRT+SBRT (18.65%) dibandingkan grup SFGRT saja (63,13%-89,09%). Sel viabel tumor di luar area radiasi juga terdapat penurunan, menunjukkan kemungkinan efek bystander. Ekspresi FOXP3 mengalami penurunan dan terjadi peningkatan %CD8+ pasca perlakuan radiasi. Kesimpulan: Induksi KSH pada babi domestik dapat dilakukan dengan pemberian DENA+PB dengan periode latensi 15-22 bulan. Penurunan jumlah sel viabel secara signifikan tampak pada kelompok perlakuan radiasi lengkap (SFGRT 1x20Gy + SBRT 3x8Gy) dengan jalur apoptosis pada area di dalam dan di luar area radiasi yang menunjukkan peran efek bystander/abscopal.
Kata kunci: DENA, karsinoma sel hati, induksi hewan coba besar, SFGRT, efek abscopal, efek bystander


Background: Spatially fractionated grid radiotherapy (SFGRT) is reported to play a role in the management of large tumors, including hepatocellular carcinoma (HCC). However, knowledge of the working mechanism of SFGRT is still limited. Large animal studies can be useful to add value to the scientific evidence. This study is the first study to induce HCC with N-Diethylnitrosamine (DENA) in domestic swine. This study aims to evaluate cell death patterns, bystander effects, abscopal effects, and immune responses of SFGRT in large experimental animal models with HCC. Method: A total of 10 domestic swine (Sus scrofa domesticus) were injected with DENA 15mg/kgBB and phenobarbital (PB) 4mg/kgBB. Subjects were evaluated periodically by ultrasound, CT scan, and blood analysis. The diagnosis of HCC is established by imaging and histopathological examination. Subjects were randomized as negative controls, positive controls, intervention group of SFGRT 1x20 Gy single dose, and intervention group of complete irradiation SFGRT 1x20 Gy + SBRT 3x8 Gy. Annexin's flowcytometry examination was performed to analyze cell death patterns; and biomarkers TNF-D, IFN-ܵ, FOXP3 were to evaluate the immune response with tumor and liver tissue samples outside and inside the radiation area. Results: Carcinogenesis was successful in all subjects with latency period of 15-22 months, in the form of HCC and hepatic angiosarcoma. An increase in FOXP3 was observed in subjects who experienced malignancy compared to negative controls, while TNF-D and IFN-ܵ OeYeOV ZeUe ORZeU. AQQe[iQ e[aPiQaWiRQ VhRZed a significant decrease in the number of viable cells on complete radiation treatment (18.65%) compared to subjects recieving SFGRT alone (63.13%-89.09%). Viable cells of tumor tissue outside the irradiation area also decreased, indicating a possible bystander effect. A decrease of FOXP3 expression and an increase of % CD8+ were found after each session of irradiation. Conclusion: HCC induction in domestic swine can be done by administering DENA+PB with a latency period of 15-22 months. A significant decrease in the number of viable cells was seen in the complete irradiation treatment group (SFGRT 1x20Gy + SBRT 3x8Gy) with apoptosis pathways inside and outside of the irradiation areas indicating the role of bystander/abscopal effects.
Keywords: DENA, hepatocellular carcinoma, large animal induction, SFGRT, abscopal effect, bystander effects.