Synergistic Action of Cisplatin and Carbon Ion Irradiation in. Adenocarcinoma of the Uterine Cervix and HeLa Cell Line. S. Shiba,1,2 M. Wakatsuki,1 N. Okonogi ...
E570
International Journal of Radiation Oncology Biology Physics
between mutation in BRCA pathway genes and response to both novel DNA repair directed agents and radiation therapy is not well understood. We characterized exosomal mutations in DNA repair genes in the tumors of men with prostate cancer, including BRCA2 and genes that encode proteins known to interact biologically with BRCA2. Materials/Methods: We identified 254 men with prostate cancer treated at our institution who consented to targeted next-generation sequencing of their tumor specimens using the OncoPanel platform; a minority (nZ7) were of African-American descent. This panel included point mutations, insertions, and deletions within exons and select introns/enhancers of 300 candidate genes with a role in oncogenesis. Fisher’s exact tests were used to identify associations between BRCA2 and related pathway mutations. Databases of published germline BRCA2 mutations were used to determine whether BRCA2 mutations found in tumors may be constitutionally inherited. Results: Of the 254 prostate tumors studied, 248 (97%) were primary tumor specimens and 7 (3%) metastases. Among the 300 genes sequenced, the most commonly encountered mutations were in TP53 (nZ35 patients), MLL2 (nZ28), ATM (nZ18), ARID1B (nZ16), NOTCH1 (nZ15), PRKDC (nZ14), and BRCA2 (nZ14). Mutations in BRCA2 were observed in 1 of 7 African-American patients. BRCA2 mutations were not correlated to any of the aforementioned mutations, nor to PALB2 or BRCA1 (pathway proteins not frequently mutated in these patients); however, there was a trend toward association of mutation in BRCA2 with mutation in MLL2 (nZ4, PZ0.055). Interestingly, mutations appeared non-randomly distributed in clusters across BRCA2 exons. A span of w75% of exon 11 starting from the 5’ terminus was devoid of mutations. This region corresponds to the previously identified ovarian cancer cluster region within BRCA2 germline carriers (OCCR1). Mutations outside of putative breast and ovarian cancer cluster regions were infrequently observed (3/18, 16.7%). Two BRCA2 mutations detected in our patients have been described in the germline of women with breast and ovarian cancer, with 4 additional mutations originating at the same nucleotide as has been reported in women with breast and ovarian cancer, albeit with different nucleotide changes. Conclusion: We have identified patterns of mutation that may reflect hotand cold-spots of BRCA2 mutations in prostate tumors; the functional implication of this clustering is unknown. BRCA2 mutations may assort independently of other errors in DNA processing. Further characterization of these defects in DNA repair may inform risk of aggressive prostate cancer and direct future use of DNA repair directed treatments and radiation therapy. Author Disclosure: V.L. Patel: None. E. Busch: None. A.V. D’Amico: None. T.R. Rebbeck: None.
Materials/Methods: Eligibility for this study was the patient received 74.4 Gy (RBE) of C-ion RT with or without cisplatin (40mg/m2/week) in two clinical trials for locally advanced adenocarcinoma of the uterine cervix. The maximum diameter of the tumor was measured by MRI before, during, at the end, and 3 months after C-ion RT, and compared tumor size reduction between patient groups with (nZ25) and without (nZ15) cisplatin. Median tumor size at diagnosis was 5.4 cm (range 3.0-8.7 cm) and was 4.4 cm (range 2.5-6.5 cm) in the groups with and without cisplatin, respectively. In vitro experiments, human uterine cervical cancer cells (HeLa cells) were irradiated with varied (13, 30 and 70 KeV/mm) linear energy transfer (LET) C-ion irradiation with or without cisplatin (5mM) that was an hour prior to irradiation. Cell survival was assessed by colony formation assay to cisplatin and 2 Gy of each LET. The surviving fractions of cells treated with irradiation plus cisplatin were normalized to the surviving fractions of cells treated with cisplatin alone. The sensitizer enhancement ratio (SER) was calculated as the ratio of the cells surviving fractions. Results: The clinical trials revealed that the concurrent use of cisplatin enhanced the size reduction compared with before and at the end of the C-ion RT. Median tumor reduction ratio of C-ion RT with cisplatin was 54% (range 16-86%), and those of C-ion RT alone was 29% (range 5-100%) (P 0.01). In vitro experiments mimicked the synergistic action: concurrent use of cisplatin significantly reduced cell survival rate after 2 Gy C-ion RT at both LET 13 KeV/mm (31% and 53%, P 0.01, SER 1.78 0.34) and LET 30 KeV/mm (27% vs. 33% P 0.05, SER 1.24 0.17). However, cisplatin reduced the cell survival rate at LET 70 KeV/mm (8% vs. 9%, P 0.1, SER 1.19 0.17), though the differences did not reach the significant level. Conclusion: This study demonstrated the synergistic action of cisplatin and C-ion irradiation on adenocarcinoma of the uterine cervix. In the present study, it was suggested that lower LET showed a trend of synergistic action. Author Disclosure: S. Shiba: None. M. Wakatsuki: None. N. Okonogi: None. S. Kato: None. T. Ohno: None. T. Kamada: None. T. Nakano: None.
3397 Synergistic Action of Cisplatin and Carbon Ion Irradiation in Adenocarcinoma of the Uterine Cervix and HeLa Cell Line S. Shiba,1,2 M. Wakatsuki,1 N. Okonogi,1 S. Kato,3 T. Ohno,4 T. Kamada,5 and T. Nakano4; 1National Institute of Radiological Sciences, Chiba, Japan, 2Department of Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi, Japan, 3Saitama Medical University International Medical Center, Saitama, Japan, 4Gunma University Heavy Ion Medical Center, Maebashi, Japan, 5Research Center Hospital for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan Purpose/Objective(s): Several clinical trials for carbon-ion radiation therapy (C-ion RT) combined with chemotherapy have been ongoing at the National Institute of Radiological Sciences. However the synergistic action of combination treatment between C-ion RT and anti-cancer drugs is still unclear. The hypothesis is that the spread-out Bragg peak (SOBP) has an LET between 10keV/mm and 80keV/mm and any synergistic action noted would be between the carbon ion RT and cisplatin, within the lower LET range. Purpose of this study was to evaluate the synergistic action of C-ion RT combined with cisplatin for adenocarcinoma of the uterine cervix in the clinical trials and in vitro experiments.
3398 The Abscopal Effect in Patients With Multiple Metastases Treated With Combination of Dendritic Cell-Based Immunotherapy and Focal Radiation Therapy K. Nakajima,1 Y. Shibamoto,2 M. Kobayashi,3 T. Takaoka,2 T. Murai,2 Y. Manabe,2 C. Sugie,1 and T. Yanagi2; 1Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan, 2Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan, 3Seren Clinic Nagoya, Nagoya, Japan Purpose/Objective(s): The abscopal effect is a phenomenon in which local radiation therapy is associated with the regression of metastatic cancer at a distance from the irradiated site. It has recently been reported that these effects are closely related to immunoregulatory mechanisms in preclinical models and clinical situation as well. Dendritic cell (DC)-based immunotherapy (DCI) can systemically induce clinical and immunological responses in cancer patients. The purpose of this study was to investigate the abscopal effects in patients treated with the combination of DCI and focal RT. Materials/Methods: We retrospectively reviewed 52 patients with multiple metastases from various cancers who were treated at our institutions with concurrent DCI and RT (cDC-RT) between 2009 and 2015. DCs were administered subcutaneously every other week for usually more than 6 months. Radiation was given as stereotactic RT, IMRT, or 3D conformal RT. The dose was determined depending on the patient; nearly full doses were used in most patients (e.g., 48-50 Gy/4 fractions, 50-60 Gy/25-30 fractions, or 39 Gy/13 fractions). Among the patients, 9 were considered eligible for this study; they had been diagnosed to have progressive or stable disease with systemic therapy or without any cancer therapy before cDC-RT and had at least one measurable tumor distant from the target lesion of irradiation. We irradiated the primary lesion or the largest
