Metabolic response after 68Ga-PSMA-PET/CT-directed IGRT/SBRT for oligometastases prostate cancer.

BACKGROUND: We used 68Ga PSMA PET/CT in the current investigation to assess the metabolic response and local control of metastasis in patients with oligometastatic prostate cancer receiving SBRT. MATERIALS AND PROCEDURES: We performed a retrospective evaluation of the medical data of all patients with oligometastatic prostate cancer who underwent stereotactic body radiation therapy (SBRT) between 2017 and 2021. Our analysis only included medical records of patients who had SBRT for oligometastatic prostate cancer and had pre and post-SBRT 68Ga PSMA PET/CT images. Patient-related (age), disease-related (Gleason score, location of metastases), and treatment-related (factors and outcomes) data were collected from the medical files. RESULTS: A total of 17 patients (28 lesions) with a median age of 69 years were included in the research. A median follow-up of 16.6 months was used (range 6-36 months). The median follow-up period for 68 Ga PSMA PET/CT was 8 months (the range was 5-24 months). The median pre-treatment PSA level was 1.7 ng/mL (range 0.39-18.3 ng/mL) compared to the post-treatment PSA nadir of 0.05 ng/mL (0.02-4.57). During the follow-up period, local control was 96%, and there was a link between PSMA avidity on PET. In the treated lesions, there were no recurrences. During follow-up, none of the patients experienced toxicities of grade 3 or above. CONCLUSIONS: SBRT is a highly successful and safe way of treating patients with oligometastatic prostate cancer. Additional research is needed to examine 68Ga PSMA PET/CT to assess further for demarcation and follow-up.

Nodal and osseous oligometastatic prostate cancer: a cohort including the introduction of PSMA-PET/CT-guided stereotactic and hypofractionated radiotherapy with elective nodal therapy.

PURPOSE: Oligometastatic prostate cancer is heavily investigated, and conventionally fractionated elective nodal treatment appears to increase biochemical relapse-free (bRFS) survival. The novelty of this report is to present elective nodal radiotherapy (ENRT) with simultaneous integrated boost with stereotactic (SBRT) or hypofractionated radiotherapy (HoFRT) for tolerance and for bRFS which we compared with SBRT of the involved field (IF) only. MATERIALS AND METHODS: Patients between 2018 and 2021 with and oligometastatic prostate cancer treated with SBRT or hypofractionation were eligible. A radiobiologically calculated simultaneous integrated boost approach enabled to encompass elective nodal radiotherapy (ENRT) with high doses to PSMA-positive nodes. A second group had only involved field (IF) nodal SBRT. RESULTS: A total of 44 patients with 80 lesions of initially intermediate- (52%) or high-risk (48%) D'Amico omPC were treated with SBRT to all visible PSMA-PET/CT lesions and 100% of the treated lesions were locally controlled after a median follow-up was 18 months (range 3-42 months). Most lesions (56/80; 70%) were nodal and the remainder osseous. Median bPFS was 16 months and ADT-free bPFS 18 months. ENRT (31 patients) versus IF (13 patients) prevented regional relapse more successfully. At univariate analysis, both initial PSA and length of the interval between primary diagnosis and biochemical failure were significant for biochemical control. Treatment was well tolerated and only two patients had toxicity ≥ grade 3 (1 GU and 1 GI, each). DISCUSSION/CONCLUSION: SBRT and hypofractionated radiotherapy at curative doses with ENRT was more effective to delay ADT than IF, controlled all treated lesions and was well tolerated.

A single-institution retrospective analysis of intraoperative radiation boost during breast-conservation treatment for breast cancer.

BACKGROUND: As part of a breast-conservation strategy for breast cancer, there are presently no data from randomized controlled studies on the use of intraoperative radiation (IORT) as a tumor bed boost. The effectiveness and safety of IORT as a boost therapy at a tertiary cancer center were retrospectively reviewed in this study. METHODS: Patients had breast-conserving surgery from 2012 to 2016 that included staging of the axillary lymph nodes, a single dose of 20 Gy IORT with 50-kV photons, whole-breast irradiation (WBI), and (neo-)adjuvant systemic treatment (if applicable). During the follow-up patients were monitored for the assessment of acute and late toxicities (using the Common Terminology Criteria for Adverse Events version 4.03). Results included ipsilateral (IBTR), contralateral (CBE), and distant metastasis-free (DMFS) breast progression-free survival, as well as overall survival (OS). RESULTS: The 68 patients had a median follow-up of 91.5 months (with a range of 9-125). Most patients (n = 51) had T1 disease and were clinically node negative. Only a small number of individuals had triple negative or high-grade illness. The majority of patients had sentinel node biopsy, and three (4.4%) had to have their tumors removed again since their original margins were positive. Finally, there were no distinct tumor bed margins. Neoadjuvant chemotherapy was administered to ten (14.7%). The median duration from BCS to WBI was 54.5 days, and conventionally fractionated WBI was used to accomplish WBI most frequently (n = 57, 96.6%). IORT was administered in a single 20 Gy dosage. 50 Gy was the median WBI dosage (range 40.05-50.4 Gy). There were no grade 4 adverse events for any patients in. Toxicities following surgery were minimal. There were only one patient with grade 3 toxicity (radiation dermatitis) to observe. Five tumor bed recurrences and two contralateral breast incident each occurred. CONCLUSION: This work adds to the preliminary evidence already in the literature and supports the use of IORT in boost settings. When randomized trials like TARGIT-B are eventually published, these hopeful findings should be prospectively evaluated.

A single-center experience with linear accelerator-based stereotactic radiotherapy for meningiomas: hypofractionation and radiosurgery.

PURPOSE: Meningioma is a common type of benign tumor that can be managed in several ways, ranging from close observation, surgical resection, and various types of radiation. We present here results from a 10 year experience treating meningiomas with a hypofractionated approach. MATERIALS AND METHODS: To define the rate of tumor control and factors associated with the relief of symptoms and radiation-related complications after radiosurgery and hypofractionated radiosurgery for patients with imaging-defined intracranial meningiomas. We reviewed the charts of 48 patients treated with stereotactic radiosurgery (SRS) or hypofractionated stereotactic radiotherapy (SRT) from 2002 to 2018. A total of 37 (82%) patients had WHO Grade 1 disease, and 11 (22%) had Grade 2. Outcomes that were analyzed included local control rates and the rate and grade of any reported toxicity. RESULTS: Only 36 patients with 38 lesions, who underwent the follow-up regime, were enrolled in the retrospective analysis. The follow-up mean was 40 months (12-120 months). 25/34 patients had surgery before the radiotherapy. Sixteen underwent SRS with a median dose of 13, 5, and 20 received hypofractionated SBRT with a median dose of 26.9 (22-45 Gy) in median six fractions (5-13 fractions). Local control at 2 and 5 years for all patients was 90 and 70%, respectively. No patient suffered from toxicity > 2 CTC. 21/36 patients showed stable disease, while 8/36 patients showed partial Remission. 7/36 developed recurrent meningioma (five in-field), only one patient with grade 1 meningioma, in a median of 22 months (13-48 months). CONCLUSION: SFRT was superior to SRS for local control in our analysis of Grade I meningiomas. This might be due to a tendency for higher EQD2 in the PTV with SFRT compared to SRS, which was reduced to avoid brain necrosis in large PTVs. Therefore, SFRT appears preferable for typical meningioma PTVs.

Modulation of radiosensitivity of DU145 prostate carcinoma cells by simvastatin.

PURPOSE: To investigate antiproliferative effects of simvastatin in combination with ionizing radiation on DU145 prostate cancer cells and its influence on cellular HMG-CoA-reductase levels. METHODS: Proliferative responses of DU145 cells were estimated by means of a clonogenic assay or the crystal violet procedure. HMG-CoA-reductase levels were measured by western blot analysis. RESULTS: The antiproliferative effects of simvastatin and radiation are dependent on simvastatin dose, radiation dose and treatment time. In vitro treatment of DU145 cells with simvastatin induced HMG-CoA-reductase levels. CONCLUSION: Ionizing radiation more profoundly reduces proliferation as compared to simvastatin exposure, while the combined application of both modalities is synergistic. The inhibition of CoA-reductase may contribute to these effects.

Linac-based stereotactic radiosurgery for brain arteriovenous malformations.

PURPOSE: Linac stereotactic radiosurgery (SRS) is gaining popularity as a form of radiation treatment for cerebral arteriovenous malformations (AVMs) since the theory of combined radiosurgical and endovascular treatment poses much uncertainty and due to significant technical progress for SRS. This study focuses on how to evaluate obliteration and re-bleeding rates, and to determine factors and adverse effects influencing obliteration after linac-based SRS for cerebral AVMs. MATERIAL AND METHODS: From a statistical record of 71 patients, 31 had partial embolisation, five surgery and 29 had no prior treatment. Using Kaplan-Meier survival and life table analyses, actuarial obliteration and annual bleeding hazard rates were calculated after SRS. RESULTS: After a follow up of 1, 2 and 3 years the actual obliteration rates were 22, 59 and 66%, respectively whereby it was noted that prior embolization had no effect on the obliteration rate. Annual bleeding hazard rates were further analyzed after stereotactic radiosurgery to be 2.1% and 1.4% for the first and second year respectively. Asymptomatic abnormalities were detected after imaging in 33.9% of patients. A dose of less than 18 Gy significantly reduced the obliteration probability. CONCLUSION: SRS is a therapeutic option for intracerebral AVM. In general, there is a low rate of morbidity and a high probability of nidus obliteration.

Functional and mutational analysis after radiation and cetuximab treatment on prostate carcinoma cell line DU145.

BACKGROUND: Epidermal Growth Factor Receptor is often overexpressed in advanced prostate carcinoma. In-vitro-studies in prostate carcinoma cell line DU145 have demonstrated increased sensibility to radiation after cetuximab treatment, but clinical data are not sufficient to date. METHODS: We analyzed effects of radiation and cetuximab in DU145 and A431 using proliferation, colony-forming-unit- and annexin-V-apoptosis-assays. Changes in protein expression of pEGFR and pERK1/2 after radiation and cetuximab treatment were analyzed. Using NGS we also investigated the impact of cetuximab long-term treatment. RESULTS: Cell counts in DU145 were reduced by 44% after 4 Gy (p = 0.006) and 55% after 4 Gy and cetuximab (p < 0.001). The surviving fraction (SF) was 0.69 after 2 Gy, 0.41 after 4 Gy and 0.15 after 6 Gy (each p < 0.001). Cetuximab treatment did not alter significantly growth reduction in 4 Gy radiated DU145 cells, p > 0.05 or SF, p > 0.05, but minor effects on apoptotic cell fraction in DU145 were detected. Using western blot, there were no detectable pEGFR and pERK1/2 protein signals after cetuximab treatment. No RAS mutation or HER2 amplification was detected, however a TP53 gen-mutation c.820G > T was found. CONCLUSIONS: Radiation inhibits cell-proliferation and colony-growth and induces apoptosis in DU145. Despite blocking MAP-Kinase-pathway using cetuximab, no significant radiation-sensitizing-effect was detected. Cetuximab treatment did not induce resistance-mutations. Further research must clarify which combination of anti-EGFR treatment strategies can increase radiation-sensitizing-effects.

GPER functions as a tumor suppressor in triple-negative breast cancer cells.

BACKGROUND: The orphan, membrane-bound estrogen receptor (GPER) is expressed at high levels in a large fraction of breast cancer patients and its expression is favorable for patients' survival. METHODS: We investigated the role of GPER as a potential tumor suppressor in triple-negative breast cancer cells MDA-MB-231 and MDA-MB-468 using cell cycle analysis and apoptosis assay. The constitutive activity of GPER was investigated. RESULTS: GPER-specific activation with G-1 agonist inhibited breast cancer cell growth in concentration-dependent manner via induction of the cell cycle arrest in G2/M phase, enhanced phosphorylation of histone H3 and caspase-3-mediated apoptosis. Analysis of the methylation status of the GPER promoter in the triple-negative breast cancer cells and in tissues derived from breast cancer patients revealed that GPER amount is regulated by epigenetic mechanisms and GPER expression is inactivated by promoter methylation. Furthermore, GPER expression was induced by stress factors, such as radiation, and GPER amount inversely correlated with the p53 expression level. CONCLUSIONS: Overall, our results establish the protective role in breast cancer tumorigenesis, and the cell surface expression of GPER makes it an excellent potential therapeutic target for triple-negative breast cancer.

In vitro combined modality treatment of prostate carcinoma cells with 17-(allylamino)-17-demethoxygeldanamycin and ionizing radiation.

BACKGROUND: The effect of 17-(allylamino)-17-demethoxygeldanamycin (17-AAG), a benzoquinone-ansamycin-type Hsp90-inhibitor, on the expression of focal adhesion kinase (FAK) and, when combined with ionizing radiation, on the clonogenicity of prostate cancer cells were determined. MATERIALS AND METHODS: FAK was analyzed by Western immunoblot. Prostate carcinoma cells were exposed either to 17-AAG alone or combined with a single radiation fraction of 3 Gy. RESULTS: FAK concentrations were reduced by 17-AAG in a time-dependent manner. Treatment with 100 nM 17-AAG for 24 h reduced clonogenicity by 90%. The plot of surviving fraction versus radiation energy dose yielded roughly parallel graphs for solvent- and 17-AAG-treated cells. CONCLUSION: 17-AAG induced rapid degradation of FAK A single radiation fraction of 3 Gy did not enhance the dose-dependent drug-effect on survival. In this sequence, the combined effect of both modalities towards clonogenicity was largely additive.

Effects of imatinib mesylate on adenoid cystic carcinomas.

BACKGROUND: Adenoid cystic carcinomas (ACCs) are rare tumors which most often arise in the salivary glands. They have a propensity for local relapse and tend to metastasize, frequently with a protracted clinical course. A substantial fraction of the tumors expresses c-Kit or the platelet-derived growth factor receptor beta (PDGFRbeta), both targets for imatinib mesylate. No standard systemic therapy is known for these neoplasms. PATIENTS AND METHODS: c-kit and PDGFRbeta-expression were determined by immunohistochemistry. Four patients with distant metastases and with at least one positive result were treated with 400 mg imatinib mesylate once daily and their response assessed. RESULTS: c-Kit and PDGFRbeta expressions were variable among the tumor samples. Toxicity was mild. No remissions were observed. CONCLUSION: These data support that c-Kit or PDGFRbeta expression per se are not prognostic for the therapeutic response of metastasized ACCs to imatinib mesylate.

Characterization of the combined cellular survival effects of benzoquinone-ansamycins and ionizing radiation.

PURPOSE: Benzoquinone-ansamycins were the first compounds characterized with the ability to inhibit the function of heat shock protein 90 and its related family members. We investigated the composite effect of ionizing radiation and of these novel substances on the survival of malignant cells. METHODS: PC-3M prostate carcinoma cells were treated in vitro with increasing radiation doses in the presence or absence of Hsp90-active and Hsp90-inactive benzoquinone-ansamycins. Cytotoxicity was determined by the crystal violet dissolution assay. RESULTS: Twenty-four hour treatment with increasing geldanamycin doses (10 nM-1 microM) reduced cellular survival by 1.5 logs for all drug dose levels. Concomitant irradiation with a single fraction of 3 Gy reduced cellular survival by 2 logs, independently of drug dose. The treatment with 100 nM geldanamycin for 24 h combined with ionizing radiation (1-5 Gy) during the first hour of drug exposure reduced cellular survival by 1.5-2 logs depending on radiation-energy dose level, while no changes in cell survival were detectable with equimolar geldampicin, a benzoquinone-ansamycin known not to inhibit Hsp90. CONCLUSIONS: The inhibition of Hsp90 and the concomitant exposure to ionizing radiation decrease cellular survival of malignant cells. These data contribute to laying the foundation for the translational use of Hsp90 inhibitors in the multimodal therapy of cancer.

A proposal for the repositioning of prophylactic breast radiotherapy of prostate cancer patients.

Patients with prostate cancer treated with small-molecular, nonsteroidal anti-androgens frequently develop mammalgia and gynecomastia. To avoid these unwanted effects, pretherapeutic radiation therapy of the male breasts is in common use. Recent findings on the effectivity of prevention and treatment of breast pain and gynecomastia, by both radiation therapy and tamoxifen, and a new comparative study, necessitate a re-evaluation of current prophylactic and therapeutic treatment options. An evidence-based treatment algorithm is derived that diverges from previous recommendations and redefines the role of preventive and therapeutic radiation therapy. For the propylaxis of gynecomastia and breast pain, tamoxifen is superior to single-dose radiation therapy with 10 Gy. Hence, if tamoxifen for this indication should prove to be safe on longer follow-up, radiation therapy would only be indicated in situations where tamoxifen therapy is impossible or contraindicated. The same is proposed for the treatment of early gynecomastia or breast pain except with tamoxifen treatment failure as an additional indication. Higher radiation doses of 4 x 5 Gy, which were shown to be effective in this setting, have not yet been evaluated against anti-estrogen therapy.

Correlation between crystal violet dissolution assay and manual colony counting on the in vitro effects of Hsp90-inhibitors.

Radiobiological experiments routinely require the estimation of cellular survival. Several cytotoxicity assays have been proposed, which have inherent advantages and disadvantages. The performance of one of them, the crystal violet dissolution assay, was examined under a broad range of conditions. PC-3M prostate carcinoma cells were exposed to ionizing radiation in the presence or absence of heat shock protein 90-inhibiting drugs. Colony formation as assessed by traditional manual counting was compared with the results from the crystal violet dissolution assay. The overall bivariate correlation of the data was determined (r = 0.743, p < 0.01). The variabilities of the data distributions from two different observers were quantitated and found to agree fairly. Ionizing radiation has a scattering-reducing effect that if plotted as Pearson-coeffcient versus radiation energy dose yields a sigmoidal distribution of data points. The crystal violet dissolution assay is a convenient tool for the rapid and reproducible determination of cellular survival and under appropriate conditions exerts a reasonable correlation to colony number.

Destabilization of the non-pathogenic, cellular prion-protein by a small molecular drug.

The presence of the normal cellular prion-protein (PrPc) is a prerequisite for the development of fatal, neurodegenerative diseases called transmissible spongiform encephalopathies (TSEs). We discovered a new biological activity of the well-known coumarin antibiotic novobiocin; the treatment of eukaryotic cells with novobiocin induces the rapid depletion of PrPc. This activity is shared by coumermycin A1, another coumarin with a related molecular structure. Novobiocin's effects on the prion-protein are time- and dose-dependent. No permanent damage to the treated cells was observed, which continue to proliferate after cessation of drug exposure. Most of the cellular proteins are unaffected by novobiocin treatment. Pretreatment with geldanamycin, an inhibitor of the aminoterminal ATPase of heat-shock protein 90 (Hsp90) partially antagonizes novobiocin's depletory activity. Concurrent treatment with the protease inhibitor chymostatin completely prevents PrPc loss. Here we show that the stability of the normal cellular prion-protein may be targeted pharmacologically. These findings open up a hitherto unknown avenue to the study of TSEs in general and may have therapeutic implications.