Frank A. Giordano

Second cancer risk after 3D-CRT, IMRT and VMAT for breast cancer

PURPOSE Second cancer risk after breast conserving therapy is becoming more important due to improved long term survival rates. In this study, we estimate the risks for developing a solid second cancer after radiotherapy of breast cancer using the concept of organ equivalent dose (OED). MATERIALS AND METHODS Computer-tomography scans of 10 representative breast cancer patients were selected for this study. Three-dimensional conformal radiotherapy (3D-CRT), tangential intensity modulated radiotherapy (t-IMRT), multibeam intensity modulated radiotherapy (m-IMRT), and volumetric modulated arc therapy (VMAT) were planned to deliver a total dose of 50 Gy in 2 Gy fractions. Differential dose volume histograms (dDVHs) were created and the OEDs calculated. Second cancer risks of ipsilateral, contralateral lung and contralateral breast cancer were estimated using linear, linear-exponential and plateau models for second cancer risk. RESULTS Compared to 3D-CRT, cumulative excess absolute risks (EAR) for t-IMRT, m-IMRT and VMAT were increased by 2 ± 15%, 131 ± 85%, 123 ± 66% for the linear-exponential risk model, 9 ± 22%, 82 ± 96%, 71 ± 82% for the linear and 3 ± 14%, 123 ± 78%, 113 ± 61% for the plateau model, respectively. CONCLUSION Second cancer risk after 3D-CRT or t-IMRT is lower than for m-IMRT or VMAT by about 34% for the linear model and 50% for the linear-exponential and plateau models, respectively.

Estimation of intracranial failure risk following hippocampal-sparing whole brain radiotherapy

PURPOSE To estimate the risk of undertreatment in hippocampal-sparing whole brain radiotherapy (HS-WBRT). METHODS Eight hundred and fifty six metastases were contoured together with the hippocampi in cranial MRIs of 100 patients. For each metastasis, the distance to the closest hippocampus was calculated. Treatment plans for 10 patients were calculated and linear dose profiles were established. For SCLC and NSCLC, dose-response curves were created based on data from studies on prophylactic cranial irradiation, allowing estimating the risk for intracranial failure. RESULTS Only 0.4% of metastases were located inside a hippocampus in 3% of all patients. SCLC showed a relatively high rate of hippocampal metastasis (18.2% of all SCLC patients) and HS-WBRT in a commonly applied fractionation scheme would increase the risk for brain relapse by ∼4% compared to conventional WBRT. NSCLC showed a lower rate of brain metastasis in the hippocampi (2.8%) and HS-WBRT would account for a slightly increased absolute risk of 0.2%. CONCLUSIONS Prophylactic or therapeutic HS-WBRT is expected to be associated with a low risk of undertreatment. For SCLC, it bears a minimally elevated risk of failure compared to standard WBRT. In NSCLC, HS-WBRT is most likely not associated with a clinically relevant increase in risk of failure.

A Lentiviral CXCR4 Overexpression and Knockdown Model in Colorectal Cancer Cell Lines Reveals Plerixafor-Dependent Suppression of SDF-1α-Induced Migration and Invasion

Background: The development of distant metastasis is associated with poor outcome in patients with colorectal cancer (CRC). The stromal cell-derived factor-1 (SDF-1) and its receptor CXC chemokine receptor 4 (CXCR4) have pivotal roles in the chemotaxis of migrating tumor cells during metastasis. Thus, hampering the SDF-1/CXCR4 cross-talk is a promising strategy to suppress metastasis. Methods: We investigated the invasive behavior of the lentivirally CXCR4overexpressing CRC cell lines SW480, SW620 and RKO in chemotaxis and invasion assays toward an SDF-1α gradient. Low endogenous CXCR4 expression levels were determined by quantitative realtime polymerase chain reaction (PCR) and fluorescence-activated cell sorting (FACS) analyses. Results: A lentiviral CXCR4 overexpression and knockdown model was established in these CRC cells. In transwell migration assays, CXCR4 overexpression favored chemotaxis and invasion of cells in all 3 lines depending on an SDF-1α gradient (p < 0.001 vs. untransduced cells). Functional CXCR4 knockdown using lentiviral short hairpin RNA (shRNA) vectors significantly decreased the migration behavior in CRC cell lines (p < 0.001), confirming a CXCR4-specific effect. Pharmacologic inhibition of the SDF-1α/CXCR4 interaction by the bicyclam PlerixaforTM at 100 µM significantly abrogated CXCR4-dependent migration and invasion through MatrigelTM (SW480, SW620, RKO; p < 0.05). Conclusion: Our results indicate that a CXCR4-antagonistic therapy might prevent tumor cell dissemination and metastasis in CRC patients, consequently improving survival.

Image-Guided Radiotherapy Using a Modified Industrial Micro-CT for Preclinical Applications

Purpose/Objective Although radiotherapy is a key component of cancer treatment, its implementation into pre-clinical in vivo models with relatively small target volumes is frequently omitted either due to technical complexity or expected side effects hampering long-term observational studies. We here demonstrate how an affordable industrial micro-CT can be converted into a small animal IGRT device at very low costs. We also demonstrate the proof of principle for the case of partial brain irradiation of mice carrying orthotopic glioblastoma implants. Methods/Materials A commercially available micro-CT originally designed for non-destructive material analysis was used. It consists of a CNC manipulator, a transmission X-ray tube (10–160 kV) and a flat-panel detector, which was used together with custom-made steel collimators (1–5 mm aperture size). For radiation field characterization, an ionization chamber, water-equivalent slab phantoms and radiochromic films were used. A treatment planning tool was implemented using a C++ application. For proof of principle, NOD/SCID/γc−/− mice were orthotopically implanted with U87MG high-grade glioma cells and irradiated using the novel setup. Results The overall symmetry of the radiation field at 150 kV was 1.04±0.02%. The flatness was 4.99±0.63% and the penumbra widths were between 0.14 mm and 0.51 mm. The full width at half maximum (FWHM) ranged from 1.97 to 9.99 mm depending on the collimator aperture size. The dose depth curve along the central axis followed a typical shape of keV photons. Dose rates measured were 10.7 mGy/s in 1 mm and 7.6 mGy/s in 5 mm depth (5 mm collimator aperture size). Treatment of mice with a single dose of 10 Gy was tolerated well and resulted in central tumor necrosis consistent with therapeutic efficacy. Conclusion A conventional industrial micro-CT can be easily modified to allow effective small animal IGRT even of critical target volumes such as the brain.

Hepatotoxicity by combination treatment of temozolomide, artesunate and Chinese herbs in a glioblastoma multiforme patient: case report review of the literature

Glioblastoma multiforme (GBM) represents an aggressive tumor type with poor prognosis. The majority of GBM patients cannot be cured. There is high willingness among patients for the compassionate use of non-approved medications, which might occasionally lead to profound toxicity. A 65-year-old patient with glioblastoma multiforme (GBM) has been treated with radiochemotherapy including temozolomide (TMZ) after surgery. The treatment outcome was evaluated as stable disease with a tendency to slow tumor progression. In addition to standard medication (ondansetron, valproic acid, levetiracetam, lorazepam, clobazam), the patient took the antimalarial drug artesunate (ART) and a decoction of Chinese herbs (Coptis chinensis, Siegesbeckia orientalis, Artemisia scoparia, Dictamnus dasycarpus). In consequence, the clinical status deteriorated. Elevated liver enzymes were noted with peak values of 238 U/L (GPT/ALAT), 226 U/L (GOT/ASAT), and 347 U/L (γ-GT), respectively. After cessation of ART and Chinese herbs, the values returned back to normal and the patient felt well again. In the literature, hepatotoxicity is well documented for TMZ, but is very rare for ART. Among the Chinese herbs used, Dictamnus dasycarpus has been reported to induce liver injury. Additional medication included valproic acid and levetiracetam, which are also reported to exert hepatotoxicity. While all drugs alone may bear a minor risk for hepatotoxicity, the combination treatment might have caused increased liver enzyme activities. It can be speculated that the combination of these drugs caused liver injury. We conclude that the compassionate use of ART and Chinese herbs is not recommended during standard radiochemotherapy with TMZ for GBM.

Analysis of Self-Inactivating Lentiviral Vector Integration Sites and Flanking Gene Expression in Human Peripheral Blood Progenitor Cells After Alkylator Chemotherapy

Abstract Hematotoxicity is a major and frequently dose-limiting side effect of chemotherapy. Retroviral methylguanine-DNA-methyltransferase (MGMT; EC 2.1.1.63) gene transfer to primitive hematopoietic progenitor cells (CD34(+) cells) might allow the application of high-dose alkylator chemotherapy with almost mild to absent myelosuppression. Because gammaretroviral vector integration was found in association with malignant or increased proliferation, novel lentiviral vectors with self-inactivating (SIN) capacity might display a safer option for future gene transfer studies. We assessed the influence of chemoselection on integration patterns in 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU)-treated and untreated human CD34(+) cells transduced with an SIN lentiviral vector carrying the MGMT(P140K) transgene, using ligation-mediated PCR (LM-PCR) and next-generation sequencing. In addition, for the first time, the local influence of the lentiviral provirus on the expression of hit and flanking genes in human CD34(+) cells was analyzed at a clonal level. For each colony, the integration site was detected (LM-PCR) and analyzed (QuickMap), and the expression of hit and flanking genes was measured (quantitative RT-PCR). Analyses of both treated and untreated CD34(+) cells revealed preferential integration into genes. Integration patterns in BCNU-treated cells showed mild, but not significant, differences compared with those found in untreated CD34(+) cells. Most importantly, when analyzing the local influence of the provirus, we saw no significant deregulation of the integration-flanking genes. These findings demonstrate that SIN vector-mediated gene transfer might display a feasible and possibly safe option for MGMT(P140K)-mediated chemoprotection of CD34(+) cells.

Axially Vascularized Tissue Engineered Bone Constructs Retain their In‐Vivo Angiogenic and Osteogenic Capacity After High Dose Irradiation

In order to introduce bone tissue engineering to the field of oncological reconstruction, we are investigating for the first time the effect of various doses of ionizing irradiation on axially vascularized bone constructs. Synthetic bone constructs were created and implanted in 32 Lewis rats. Each construct was axially vascularized through an arteriovenous loop made by direct anastomosis of the saphenous vessels. After 2 weeks, the animals received ionizing irradiation of 9 Gy, 12 Gy and 15 Gy, and were accordingly classified to groups I, II and III, respectively. Group IV was not irradiated and acted as a control. Tissue generation, vascularity, cellular proliferation and apoptosis were investigated either 2 or 5 weeks after irradiation through micro‐computed tomography, histomorphometry and real‐time polymerase chain reaction (PCR). At 2 weeks after irradiation, tissue generation and central vascularity were significantly lower and apoptosis was significantly higher in groups II and III than group IV, but without signs of necrosis. Cellular proliferation was significantly lower in groups I and II. After 5 weeks, the irradiated groups showed improvement in all parameters in relation to the control group, indicating a retained capacity for angiogenesis after irradiation. PCR results confirmed the expression of osteogenesis‐related genes in all irradiated groups. Dense collagen was detected 5 weeks after irradiation, and one construct showed discrete islands of bone indicating a retained osteogenic capacity after irradiation. This demonstrates for the first time that axial vascularization was capable of supporting a synthetic bone construct after a high dose of irradiation that is comparable to adjuvant radiotherapy. Copyright

Immunotherapy Combined with Large Fractions of Radiotherapy: Stereotactic Radiosurgery for Brain Metastases—Implications for Intraoperative Radiotherapy after Resection

Brain metastases (BM) affect approximately a third of all cancer patients with systemic disease. Treatment options include surgery, whole-brain radiotherapy, or stereotactic radiosurgery (SRS) while chemotherapy has only limited activity. In cases where patients undergo resection before irradiation, intraoperative radiotherapy (IORT) to the tumor bed may be an alternative modality, which would eliminate the repopulation of residual tumor cells between surgery and postoperative radiotherapy. Accumulating evidence has shown that high single doses of ionizing radiation can be highly efficient in eliciting a broad spectrum of local, regional, and systemic tumor-directed immune reactions. Furthermore, immune checkpoint blockade (ICB) has proven effective in treating antigenic BM and, thus, combining IORT with ICB might be a promising approach. However, it is not known if a low number of residual tumor cells in the tumor bed after resection is sufficient to act as an immunizing event opening the gate for ICB therapies in the brain. Because immunological data on tumor bed irradiation after resection are lacking, a rationale for combining IORT with ICB must be based on mechanistic insight from experimental models and clinical studies on unresected tumors. The purpose of the present review is to examine the mechanisms by which large radiation doses as applied in SRS and IORT enhance antitumor immune activity. Clinical studies on IORT for brain tumors, and on combined treatment of SRS and ICB for unresected BM, are used to assess the safety, efficacy, and immunogenicity of IORT plus ICB and to suggest an optimal treatment sequence.

Intraoperative radiotherapy (IORT)—a resurrected option for treating glioblastoma?

Despite surgical resection, radiochemotherapy and adjuvant chemotherapy, glioblastoma multiforme (GBM) is still associated with an extremely poor prognosis. As almost all tumors recur locally and evidence for a radiation dose-dependent effect on survival exists, intraoperative radiotherapy (IORT) could be an approach to avoid tumor cell proliferation between surgery and radiochemotherapy while sparing healthy tissue. The majority of previous studies used forward-scattering electron tubes (resembling intraoperative electron radiotherapy, IOERT) and suffered from technical and geometrical limitations. Consequently, the outcomes in previous studies range from highly beneficial to merely effective. This review shall give an overview on past, present and future applications of IORT for GBM and shall discuss what prospective steps are to be taken to thoroughly assess whether the approach has the ability to prolong patient survival.

Mitogenic signalling in the absence of epidermal growth factor receptor activation in a human glioblastoma cell line

Epidermal growth factor receptor (EGFR) gene amplification and overexpression are commonly present in glioblastoma, and confer advantages of growth, invasiveness and radio/chemotherapy-resistance for tumour cells. Here, we assessed the role of EGFR activation for downstream mitogenic signalling in the commonly used glioblastoma cell line U251. Despite the high expression level, activation of EGFR under standard culture conditions was low. Intact EGFR function was verified by the rapid phosphorylation of EGFR and downstream mitogen-activated protein (MAP) kinase ERK1/2 upon addition of exogenous EGF to serum-starved cells. By contrast, addition of fetal bovine serum (FBS) activated downstream ERK1/2 via the MAP kinase kinase without phosphorylating EGFR. A phospho-receptor tyrosine kinase array showed FBS-induced activation of insulin-like growth factor-1 receptor (IGF-1R), and the IGF-1R inhibitor AG1024 inhibited FBS-induced phosphorylation of ERK1/2, implying IGF-1R as the major driver of FBS-associated mitogenic signalling in the absence of exogenous EGF. These findings have important implications for in vitro drug testing in glioblastoma. Moreover, activation of ERK1/2 was also strongly influenced by growth state and cell density of U251 cultures. Re-seeding exponentially growing cultures at high cell density induced p27/CDKN1B expression and suppressed P-ERK1/2 indicating a certain regulation of proliferation by contact inhibition. Strikingly, highly activated ERK1/2 signalling and cell-cycle progression occurred when cells were released from plateau phase regardless of high seeding density. This phenomenon might implicate a proliferation response in the early recurrence observed after clinical therapy in glioblastoma patients. However, whether it will recapitulate in vivo remains to be demonstrated.