Christoph Oehler

Ionizing Radiation Antagonizes Tumor Hypoxia Induced by Antiangiogenic Treatment

Purpose: The combined treatment modality of ionizing radiation with inhibitors of angiogenesis is effective despite the supposition that inhibition of angiogenesis might increase tumor hypoxia and thereby negatively affect radiation sensitivity. To directly assess this still controversial issue, we analyzed treatment-dependent alterations of tumor oxygenation in response to inhibition of angiogenesis alone, ionizing radiation, and combined treatment. Experimental Design: Serial measurements with high-resolution [18F]fluoromisonidazole positron emission tomography and immunohistochemical detection of the endogenous hypoxia marker glucose transporter-1 were done to determine tumor hypoxia in a murine mammary carcinoma allograft model. Results: Inhibition of angiogenesis with the clinically relevant vascular endothelial growth factor receptor tyrosine kinase inhibitor PTK787/ZK222584 reduced microvessel density but had only minimal effects on tumor growth, tumor cell apoptosis, and proliferation. However, PTK787/ZK222584 treatment increased overall and local tumor hypoxia as revealed by extended expression of the hypoxia marker glucose transporter-1 and increased uptake of [18F]fluoromisonidazole. Fractionated irradiation induced a strong growth delay, which was associated with enhanced apoptosis and reduced proliferation of tumor cells but only minor effects on microvessel density and allograft oxygenation. Combined treatment with fractionated irradiation resulted in extended tumor growth delay and tumor cell apoptosis but no increase in tumor hypoxia. Conclusions: These results show that irradiation antagonizes the increase of hypoxia by vascular endothelial growth factor receptor tyrosine kinase inhibition and abrogates the potential negative effect on tumor hypoxia. Thus, the risk of treatment-induced hypoxia by inhibitors of angiogenesis exists but is kept minimal when combined with a cytotoxic treatment modality.

Quality of life and tumor control after short split-course chemoradiation for anal canal carcinoma

PurposeTo evaluate quality of life (QOL) and outcome of patients with anal carcinoma treated with short split-course chemoradiation (CRT).MethodsFrom 1991 to 2005, 58 patients with anal cancer were curatively treated with CRT. External beam radiotherapy (52 Gy/26 fractions) with elective groin irradiation (24 Gy) was applied in 2 series divided by a median gap of 12 days. Chemotherapy including fluorouracil and Mitomycin-C was delivered in two sequences. Long-term QOL was assessed using the site-specific EORTC QLQ-CR29 and the global QLQ-C30 questionnaires.ResultsFive-year local control, colostomy-free survival, and overall survival were 78%, 94% and 80%, respectively. The global QOL score according to the QLQ-C30 was good with 70 out of 100. The QLQ-CR29 questionnaire revealed that 77% of patients were mostly satisfied with their body image. Significant anal pain or fecal incontinence was infrequently reported. Skin toxicity grade 3 or 4 was present in 76% of patients and erectile dysfunction was reported in 100% of male patients.ConclusionsShort split-course CRT for anal carcinoma seems to be associated with good local control, survival and long-term global QOL. However, it is also associated with severe acute skin toxicity and sexual dysfunction. Implementation of modern techniques such as intensity-modulated radiation therapy (IMRT) might be considered to reduce toxicity.

Patupilone (epothilone B) for recurrent glioblastoma: clinical outcome and translational analysis of a single-institution phase I/II trial.

Background: Patients with glioblastoma (GBM) inevitably develop recurrent or progressive disease after initial multimodal treatment and have a median survival of 6–9 months from time of progression. To date, there is no accepted standard treatment for GBM relapse or progression. Patupilone (EPO906) is a novel natural microtubule-stabilizing cytotoxic agent that crosses the blood-brain barrier and has been found to have preclinical activity in glioma models. Methods: This is a single-institution, early-phase I/II trial of GBM patients with tumor progression who qualified for second surgery with the goal of evaluating efficacy and safety of the single-agent patupilone (10 mg/m2, every 3 weeks). Patients received patupilone 1 week prior to second surgery and every 3 weeks thereafter until tumor progression or toxicity. Primary end points were progression-free survival (PFS) and overall survival (OS) at 6 months as well as patupilone concentration in tumor tissue. Secondary end points were toxicity, patupilone concentration in plasma and translational analyses for predictive biomarkers. Results: Nine patients with a mean age of 54.6 ± 8.6 years were recruited between June 2008 and April 2010. Median survival and 1-year OS after second surgery were 11 months (95% CI, 5–17 months) and 45% (95% CI, 14–76), respectively. Median PFS was 1.5 months (95% CI, 1.3–1.7 months) and PFS6 was 22% (95% CI, 0–46), with 2 patients remaining recurrence-free at 9.75 and 22 months. At the time of surgery, the concentration of patupilone in tumor tissue was 30 times higher than in the plasma. Tumor response was not predictable by the tested biomarkers. Treatment was generally well tolerated with no hematological, but cumulative, though reversible sensory neuropathy grade ≤3 was seen in 2 patients (22%) at 8 months and grade 4 diarrhea in the 2nd patient (11%). Non-patupilone-related peri-operative complications occurred in 2 patients resulting in discontinuation of patupilone therapy. There were no neurocognitive changes 3 months after surgery compared to baseline. Conclusions: In recurrent GBM, patupilone can be given safely pre- and postoperatively. The drug accumulates in the tumor tissue. The treatment results in long-term PFS in some patients. Patupilone represents a valuable novel compound which deserves further evaluation in combination with radiation therapy in patients with GBM.

Current Concepts for the Combined Treatment Modality of Ionizing Radiation with Anticancer Agents

In current applied radiobiology, there exists a tremendous effort in basic and translational research to identify novel treatment modalities combining ionizing radiation with anticancer agents. This is mainly due to the highly improved molecular understanding of intrinsic radioresistance and the profiling of cellular stress responses to irradiation during recent years. Ionizing radiation not only damages DNA but also affects multiple cellular components that induce a multi-layered stress response. The treatment responses can be restricted to the individual cell level but might also be part of an intercellular stress communication network. Both DNA damage-induced signaling (which results in cell cycle arrest and induction of the DNA-repair machinery) and also ionizing radiation-induced signal transduction cascades, which are generated at cellular sites distant from and independent of DNA-damage, represent interesting targets for anticancer treatment modalities to sensitize for ionizing radiation. Due to the lack of molecular knowledge classic radiobiology assembled the cellular and tissue responses into four groups (4 Rs of radiotherapy) which describe biological factors influencing the treatment response to fractionated radiotherapy. These classic 4 Rs are Repair, Reassortment, Repopulation and Reoxygenation. With the tremendous progress in molecular oncology we now begin to understand theses factors on the molecular level. At the same time this classification may guide modern molecular radiobiologists to identify novel pharmaceuticals and antisignaling agents which can modulate the treatment response to irradiation. In this review we describe current approaches to sensitize tumor cells with novel anticancer agents along the lines of these 4 Rs.

c-MYC expression sensitizes medulloblastoma cells to radio- and chemotherapy and has no impact on response in medulloblastoma patients

BackgroundTo study whether and how c-MYC expression determines response to radio- and chemotherapy in childhood medulloblastoma (MB).MethodsWe used DAOY and UW228 human MB cells engineered to stably express different levels of c-MYC, and tested whether c-MYC expression has an effect on radio- and chemosensitivity using the colorimetric 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt (MTS) assay, clonogenic survival, apoptosis assays, cell cycle analysis, and western blot assessment. In an effort to validate our results, we analyzed c-MYC mRNA expression in formalin-fixed paraffin-embedded tumor samples from well-documented patients with postoperative residual tumor and compared c-MYC mRNA expression with response to radio- and chemotherapy as examined by neuroradiological imaging.ResultsIn DAOY - and to a lesser extent in UW228 - cells expressing high levels of c-MYC, the cytotoxicity of cisplatin, and etoposide was significantly higher when compared with DAOY/UW228 cells expressing low levels of c-MYC. Irradiation- and chemotherapy-induced apoptotic cell death was enhanced in DAOY cells expressing high levels of c-MYC. The response of 62 of 66 residual tumors was evaluable and response to postoperative radio- (14 responders (CR, PR) vs. 5 non-responders (SD, PD)) or chemotherapy (23 CR/PR vs. 20 SD/PD) was assessed. c-MYC mRNA expression was similar in primary MB samples of responders and non-responders (Mann-Whitney U test, p = 0.50, ratio 0.49, 95% CI 0.008-30.0 and p = 0.67, ratio 1.8, 95% CI 0.14-23.5, respectively).Conclusionsc-MYC sensitizes MB cells to some anti-cancer treatments in vitro. As we failed to show evidence for such an effect on postoperative residual tumors when analyzed by imaging, additional investigations in xenografts and larger MB cohorts may help to define the exact function of c-MYC in modulating response to treatment.

PTV margin definition in hypofractionated IGRT of localized prostate cancer using cone beam CT and orthogonal image pairs with fiducial markers

PurposeTo evaluate PTV margins for hypofractionated IGRT of prostate comparing kV/kV imaging or CBCT.Patients and methodsBetween 2009 and 2012, 20 patients with low- (LR), intermediate- (IR) and high-risk (HR) prostate cancer were treated with VMAT in supine position with fiducial markers (FM), endorectal balloon (ERB) and full bladder. CBCT’s and kV/kV imaging were performed before and additional CBCT’s after treatment assessing intra-fraction motion. CTVP for 5 patients with LR and CTVPSV for 5 patients with IR/HR prostate cancer were contoured independently by 3 radiation oncologists using MRI. The van Hark formula (PTV margin =2.5Σ +0.7σ) was applied to calculate PTV margins of prostate/seminal vesicles (P/PSV) using CBCT or FM.Results172 and 52 CBCTs before and after RT and 507 kV/kV images before RT were analysed. Differences between FM in CBCT or in planar kV image pairs were below 1 mm. Accounting for both random and systematic uncertainties anisotropic PTV margins were 5-8 mm for P (LR) and 6-11 mm for PSV (IR/HR). Random uncertainties like intra-fraction and inter-fraction (setup) uncertainties were of similar magnitude (0.9-1.4 mm). Largest uncertainty was introduced by CTV delineation (LR: 1-2 mm, IR/HR: 1.6-3.5 mm). Patient positioning using bone matching or ERB-matching resulted in larger PTV margins.ConclusionsFor IGRT CBCT or kV/kV-image pairs with FM are interchangeable in respect of accuracy. Especially for hypofractionated RT, PTV margins can be kept in the range of 5 mm or below if stringent daily IGRT, ideally including prostate tracking, is applied. MR-based CTV delineation optimization is recommended.

The microtubule stabilizer patupilone (epothilone B) is a potent radiosensitizer in medulloblastoma cells

Concurrent radiochemotherapy for medulloblastoma includes the microtubule disrupting agent vincristine; however, vincristine alone or as part of a combined treatment regimen is highly toxic. A major goal is therefore to replace vincristine with novel potent chemotherapeutic agents-in particular, with microtubule stabilizing and destabilizing compounds-with a larger therapeutic window. Here, we investigated the antiproliferative, cytotoxic and radiosensitizing effect of patupilone (epothilone B [EPO906]), a novel, non-taxane-related and nonneurotoxic microtubule-stabilizing agent in human medulloblastoma cell lines. The antiproliferative and cytotoxic effects of patupilone alone and in combination with ionizing radiation was determined in the 3 representative human medulloblastoma cell lines D341Med, D425Med, and DAOY. Patupilone alone effectively reduced the proliferative activity and clonogenicity of all medulloblastoma cell lines tested at picomolar concentrations (50-200 pM) and resulted in an at least additive anticlonogenic effect in combination with clinically relevant doses of ionizing radiation (2 or 5 Gy). Cell-cycle analysis revealed a sequential G2-M arrest and sub-G1 accumulation in a dose- and treatment-dependent manner after exposure to patupilone. In tumor xenografts derived from D425Med cells, a minimal treatment regimen with patupilone and fractionated irradiation (1 × 2 mg/kg plus 3 × 3 Gy) resulted in an extended tumor growth delay for the 2 single treatment modalities alone and a supra-additive treatment response for the combined treatment modality, with complete tumor regressions. These results demonstrate the potent efficacy of patupilone against medulloblastoma cell lines and indicate that patupilone represents a promising candidate to replace vincristine as part of a combined treatment strategy with ionizing radiation.

Chemo-radiation with or without mandatory split in anal carcinoma: experiences of two institutions and review of the literature

BackgroundThe split-course schedule of chemo-radiation for anal cancer is controversial.MethodsEighty-four patients with invasive anal cancer treated with definitive external beam radiotherapy (RT) with a mandatory split of 12 days (52 patients, Montreal, Canada) or without an intended split (32 patients, Zurich, Switzerland) were reviewed. Total RT doses were 52 Gy (Montreal) or 59.4 Gy (Zurich) given concurrently with 5-FU/MMC.ResultsAfter a mean follow-up of 40 ± 27 months, overall survival and local tumor control at 5 years were 57% and 78% (Zurich) compared to 67% and 82% (Montreal), respectively. Split duration of patients with or without local relapse was 15 ± 7 d vs. 14 ± 7 d (Montreal, NS) and 11 ± 11 d vs. 5 ± 7 d (Zurich; P < 0.001). Patients from Zurich with prolonged treatment interruption (≥ 7 d) had impaired cancer-specific survival compared with patients with only minor interruption (<7 d) (P = 0.06). Bowel toxicity was associated with prolonged RT (P = 0.03) duration as well as increased relapse probability (P = 0.05). Skin toxicity correlated with institution and was found in 79% (Montreal) and 28% (Zurich) (P < 0.0001).ConclusionsThe study design did not allow demonstrating a clear difference in efficacy between the treatment regimens with or without short mandatory split. Cause-specific outcome appears to be impaired by unplanned prolonged interruption.

Prevention of Acute Radiation-Induced Skin Reaction with NPE® Camellia Sinensis Nonfermentatum Extract in Female Breast Cancer Patients Undergoing Postoperative Radiotherapy: A Single Centre, Prospective, Open-Label Pilot Study

Background To assess effectiveness of NPE, a proprietary Camellia sinensis nonfermentatum (CSNF) extract, in prevention and recovery of acute radiation-induced skin reaction (ARSR) and skin care during postoperative whole breast radiotherapy (RT). Methods Twenty patients were enrolled in this single centre, prospective, open-label pilot study. The outcomes of 20 prospective data sets were compared with 100 retrospectively collected matched data sets derived from hospital records. The preventive CSNF gel (2.5%) was administered 1 to 2 hours before each session on the irradiated fields. The care CSNF lotion (0.4%) was administered as 7-day pretreatment after each RT session, twice daily between RT sessions, and 4 to 8 weeks thereafter. The control group was treated according to the hospital care guidelines. The primary endpoint was time to ARSR ≥ Grade 2 (CTCAE v4.03); secondary endpoints were frequencies of ARSR grades 1, 2, 3, and 4, recovery of ARSR, frequencies of interruption and RT stop, complications and required rescue interventions, and tolerability of CSNF. Results Time to ARSR ≥ G2 (censoring) was significantly longer (p = 0.014) in the CSNF group. The hazard ratio was 2.33 (95% CI: 1.15–4.72), demonstrating a 50% decrease in the risk of developing ARSR ≥ G2. There was a trend to faster recovery from ARSR G2 in the CSNF group (100% versus 47%; p = 0.078). The proportion of patients requiring rescue treatment during RT and follow-up was markedly higher in the control compared to the CSNF group (1% to 51% versus 0% to 15%). CSNF gel and lotion were well tolerated both during and after RT. Conclusions This pilot study provides the first evidence on the potential pharmacological effectiveness of CSNF extract in prevention of RT-induced ARSR and recovery of skin irritation in patients undergoing postoperative whole breast RT and may reflect a novel concept for prevention of RT-induced ARSR and care of irritated skin.

PET-CT guided SIB-IMRT combined with concurrent 5-FU/MMC for the treatment of anal cancer

Abstract Background: To evaluate local control (LC), survival and toxicity in anal cancer patients treated with intensity-modulated radiation therapy (IMRT) and concurrent chemotherapy at a single institution. Material and methods: From August 2010 to May 2015, 26 patients were treated at our institution with IMRT and concurrent 5-fluorouracil/mitomycin-C (5-FU/MMC) for localized squamous cell carcinoma of the anal canal (SCCAC). Radiotherapy (RT) with 50.4–60 Gy was delivered with a sequential boost in 31%, and a simultaneous-integrated boost (SIB-IMRT) in 69% of cases. Initial staging was based on PET-CT and MRI. Clinical measures of interest were the influence of PET-CT on staging and treatment planning, LC, disease free survival (DFS), overall survival (OS), colostomy free survival (CFS) and toxicities. Results: Median age was 61 years, 22 patients (85%) were female, and no patient was HIV-positive. The proportion of patients with stage I, II, IIIA and IIIB disease was 15%, 35%, 23% and 27%, respectively. PET-CT modified the extent of nodal disease in 9/23 cases (39%) and lead to major changes in treatment planning in 4/23 patients (17%). MRI was more accurate at identifying T4 disease. RT was delivered at full dose in 26 patients (100%) and chemotherapy in 22/26 patients (85%). Two patients (7.7%) required RT breaks. Median follow-up was 35 months [IQR: 19–52]. The 2-year LC, DFS, OS and CFS were 100%, 100%, 100% and 92%. Acute grade ≥3 dermatitis and diarrhea occurred in 73% and 8% of cases, respectively. Grade 3–4 neutropenia was seen in 10/23 patients (43%). Four patients (15%) developed chronic grade 2 GI toxicity. Conclusions: PET-CT provided additional information leading to major changes in treatment planning for 17% of patients. Considering our excellent outcomes, routine use of PET-CT as standard staging modality and IMRT planning procedure appears justified for patients with SCCAC.