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MELK and EZH2 RNA expression

MYCN/MYC expression in N-type and S-type neuroblastoma cell lines

Maternal embryonic leucine zipper kinase (MELK) activates pathways that mediate aggressive tumor growth and therapy resistance in many types of adult cancers. Pharmacologic and genomic inhibition of MELK impairs tumor growth and increases sensitivity to radiation and chemotherapy. On the basis of these promising preclinical studies, early-phase adult clinical trials testing the MELK inhibitor OTS167 are ongoing. To investigate whether MELK is also a therapeutic target in neuroblastoma, we analyzed MELK expression in primary tumors and cell lines, and examined the effects of OTS167 on neuroblastoma growth. In primary tumors, high levels of MELK were associated with advanced stage disease and inferior survival. Higher levels of MELK were also detected in tumorigenic versus nontumorigenic neuroblastoma cell lines, and cells with higher levels of MELK expression were more sensitive to OTS167 than low-MELK expressing cells. OTS167 suppressed the growth of neuroblastoma xenografts, and in a preclinical model of minimal residual disease, survival was prolonged with MELK inhibition. OTS167 treatment downregulated MELK and its target enhancer of zeste homolog 2 (EZH2), a component of the polycomb repressive complex 2 (PRC2) that is known to modulate the DNA damage response. We also show that OTS167 reduced the formation of collapsed replication forks induced by camptothecin or radiation. Taken together, our results indicate that MELK indirectly mediates efficient processing of replication-associated DNA lesions in neuroblastoma, and that OTS167 sensitizes cells to DNA-damaging agents by abrogating this process. Further studies evaluating the activity of combination treatment regimens with OTS167 in neuroblastoma are warranted.

pRPA32 expression in neuroblastoma cells treated with OTS167 and CPT.

Purpose: Molecular-based cancer tests have been developed to augment the standard clinical and pathologic features used to tailor treatments to individual breast cancer patients. Homologous recombination (HR) repairs double-stranded DNA breaks and promotes tolerance to lesions that disrupt DNA replication. Recombination Proficiency Score (RPS) quantifies HR efficiency based on the expression of four genes involved in DNA damage repair. We hypothesized low RPS values can identify HR-deficient breast cancers most sensitive to DNA-damaging chemotherapy.Experimental Design: We collected pathologic tumor responses and tumor gene expression values for breast cancer patients that were prospectively enrolled on clinical trials involving preoperative chemotherapy followed by surgery (N = 513). We developed an algorithm to calculate breast cancer–specific RPS (RPSb) values on an individual sample basis.Results: Low RPSb tumors are approximately twice as likely to exhibit a complete pathologic response or minimal residual disease to preoperative anthracycline-based chemotherapy as compared with high RPSb tumors. Basal, HER2-enriched, and luminal B breast cancer subtypes exhibit low RPSb values. In addition, RPSb predicts treatment responsiveness after controlling for clinical and pathologic features, as well as intrinsic breast subtype.Conclusions: Overall, our findings indicate that low RPS breast cancers exhibit aggressive features at baseline, but they have heightened sensitivity to DNA-damaging chemotherapy. Low RPSb values in basal, HER2-enriched, and luminal B subtypes provide a mechanistic explanation for their clinical behaviors and genomic instability. RPSb augments standard clinical and pathologic features used to tailor treatments, thereby enabling more personalized treatment strategies for individual breast cancer patients. Clin Cancer Res; 23(15); 4493–500. ©2017 AACR.

This file includes: (1) legends for Supplementary Figures S1-S8 and Tables S1-S5 and (2) Supplementary Figures S1-S8. Figure S1: Study flow chart for selection of breast cancer patients. Figure S2: Distributions of SCAN normalized gene expression data. Figure S3: Schematic for development of breast cancer-specific RPS values. Figure S4: Variable importance of clinical, pathologic and gene expression features. Figure S5: RPS values in BRCA-mutated clinical breast cancers. Figure S6: RPS associates with adverse clinical-pathologic features. Figure S7: RPS predicts residual cancer burden following neoadjuvant doxorubicinbased chemotherapy in breast cancer. Figure S8: RPS values as a function of hormone receptor and HER2 in breast cancer.

PDF file - 403KB, Supplemental Figure 1. Quantifications of western blots. Supplemental Figure 2. Knockdown of RAD51 in PC3 does not protect cells from the toxicity of ionizing radiation. Supplemental Table 1. Quantifications of statistical significance are displayed for the RS-1 toxicity data that are displayed in Figure 2. Supplemental Methods. Chemical synthesis of compounds.

Homologous recombination (HR) is a primary DNA double-strand breaks (DSBs) repair mechanism. The recombinases Rad51 and Dmc1 are highly conserved in the RecA family; Rad51 is mainly responsible for DNA repair in somatic cells during mitosis while Dmc1 only works during meiosis in germ cells. This spatiotemporal difference is probably due to their distinctive mismatch tolerance during HR: Rad51 does not permit HR in the presence of mismatches, whereas Dmc1 can tolerate certain mismatches. Here, the cryo-EM structures of Rad51–DNA and Dmc1–DNA complexes revealed that the major conformational differences between these two proteins are located in their Loop2 regions, which contain invading single-stranded DNA (ssDNA) binding residues and double-stranded DNA (dsDNA) complementary strand binding residues, stabilizing ssDNA and dsDNA in presynaptic and postsynaptic complexes, respectively. By combining molecular dynamic simulation and single-molecule FRET assays, we identified that V273 and D274 in the Loop2 region of human RAD51 (hRAD51), corresponding to P274 and G275 of human DMC1 (hDMC1), are the key residues regulating mismatch tolerance during strand exchange in HR. This HR accuracy control mechanism provides mechanistic insights into the specific roles of Rad51 and Dmc1 in DNA double-strand break repair and may shed light on the regulatory mechanism of genetic recombination in mitosis and meiosis.

Cumulative evidence suggests that the addition of platinum agents as neoadjuvant chemotherapy (NACT) could improve the pathologic complete response (pCR) rate in triple-negative breast cancer (TNBC). We aimed to develop a DNA homologous recombination (HR)-associated gene expression score to predict tumor sensitivity to platinum-based NACT in TNBC. A retrospective cohort of 127 patients who were diagnosed with TNBC and received platinum-based NACT in Fudan University Shanghai Cancer Center from 2012 to 2017 was included in this study. Using quantitative reverse transcription-polymerase chain reaction (qRT-PCR), the expression levels of eight HR-associated genes were analyzed from formalin-fixed paraffin-embedded core-needle biopsy samples obtained before NACT. A random forest model was built to estimate the weight of each gene expression level and clinicopathological factors. The training set was used to modulate parameters and select the best model. The performance of the final model was evaluated in the validation set. A 4-gene (BRCA1, XRCC5, PARP1, and RAD51) scoring system was developed. TNBC patients with a higher score had a nearly fourfold likelihood of achieving pCR to platinum-based NACT compared with patients with a lower score [odds ratio (OR) = 3.878; P

Homologous recombination (HR) serves multiple roles in DNA repair that are essential for maintaining genomic stability, including double-strand DNA break (DSB) repair. The central HR protein, RAD51, is frequently overexpressed in human malignancies, thereby elevating HR proficiency and promoting resistance to DNA-damaging therapies. Here, we find that the non-canonical NF-κB factors p100/52, but not RelB, control the expression of RAD51 in various human cancer subtypes. While p100/p52 depletion inhibits HR function in human tumor cells, it does not significantly influence the proficiency of non-homologous end joining, the other key mechanism of DSB repair. Clonogenic survival assays were performed using a pair DLD-1 cell lines that differ only in their expression of the key HR protein BRCA2. Targeted silencing of p100/p52 sensitizes the HR-competent cells to camptothecin, while sensitization is absent in HR-deficient control cells. These results suggest that p100/p52-dependent signaling specifically controls HR activity in cancer cells. Since non-canonical NF-κB signaling is known to be activated after various forms of genomic crisis, compensatory HR upregulation may represent a natural consequence of DNA damage. We propose that p100/p52-dependent signaling represents a promising oncologic target in combination with DNA-damaging treatments.

The genomic drivers of immune exclusion in colorectal cancer liver metastases (CRCLM) remain poorly understood. Chromosomal instability (CIN), resulting in aneuploidy and genomic rearrangements, is the central pathway of mismatch repair-proficient colorectal cancer pathogenesis; however, it is unknown whether CIN impacts the outcomes of patients with limited spread of CRCLM treated with curative intent cytotoxic chemotherapy and surgery. Herein, we examined the relationship between CIN and the molecular subtypes of CRCLM, immune signaling, treatment sensitivity, and patient outcomes in three independent CRCLM patient cohorts. We established that a previously developed 70-gene CIN signature (CIN70) is a reliable measure of CIN, encompassing features of both aneuploidy and cellular proliferation. We demonstrated that tumors with the canonical subtype of CRCLM exhibit elevated levels of CIN and aneuploidy. Genomically unstable tumors were associated with an immune-depleted tumor microenvironment, and patients with genomically unstable tumors were at increased risk for disease progression in adverse metastatic sites, resulting in poor progression-free and overall survival. However, high-CIN tumors were particularly susceptible to DNA-damaging chemotherapies, including topoisomerase inhibitors, as well as radiation therapy. Treatment with genotoxic agents depleted CIN-rich cell populations, which resulted in a concomitant increase in intratumoral CD8+ T-cells in patients with primary rectal, breast, and bladder cancer. Taken together, we propose a mechanistic explanation for why cytotoxic chemotherapy can augment anti-tumor immunity and improve outcomes in patients with genomically unstable cancers.

Immune checkpoint blockade (ICB) improves outcomes in non-small cell lung cancer (NSCLC) though most patients progress. There are limited data regarding molecular predictors of progression. In particular, there is controversy regarding the role of CDKN2A loss-of-function (LOF) in ICB resistance. We analyzed 139 consecutive patients with advanced NSCLC who underwent NGS prior to ICB initiation to explore the association of CDKN2A LOF with clinical outcomes. 73% were PD-L1 positive (≥ 1%). 48% exhibited high TMB (≥ 10 mutations/megabase). CDKN2A LOF was present in 26% of patients and was associated with inferior PFS (multivariate hazard ratio [MVA-HR] 1.66, 95% CI 1.02–2.63, p = 0.041) and OS (MVA-HR 2.08, 95% CI 1.21–3.49, p = 0.0087) when compared to wild-type (WT) patients. These findings held in patients with high TMB (median OS, LOF vs. WT 10.5 vs. 22.3 months; p = 0.069) and PD-L1 ≥ 50% (median OS, LOF vs. WT 11.1 vs. 24.2 months; p = 0.020), as well as in an independent dataset. CDKN2A LOF vs. WT tumors were twice as likely to experience disease progression following ICB (46% vs. 21%; p = 0.021). CDKN2A LOF negatively impacts clinical outcomes in advanced NSCLC treated with ICB, even in high PD-L1 and high TMB tumors. This novel finding should be prospectively validated and presents a potential therapeutic target.

Cells that lack PTEN function are radiation sensitive in cell culture-based experimental systems; therefore, patients with Cowden Syndrome (CS) may carry an increased risk for normal tissue injury after radiotherapy. Here we present the first such case of a patient with genetically-confirmed CS who, indeed, experienced greater than expected toxicity following two separate courses of radiotherapy. While a causal relationship between CS and radiation sensitivity remains unclear, this observation suggests the need for further study in larger cohorts of CS patients.

Background: Recent studies incorporating dose escalated radiation identified heart dose as a predictor of cardiac toxicity in unresectable lung cancer patients. Whether conventionally dosed radiation impacts cardiac events remains unclear. Methods: Stage III lung cancer patients undergoing definitive chemoradiation to 60–70 Gy were analyzed. Clinical and dosimetric factors (mean heart dose, heart V5-60 in 5 Gy increments) were analyzed against freedom from ≥ grade 3 cardiac events and overall survival (OS) by log-rank test. Multivariable analysis (MVA) for factors significant on univariate analysis was performed by Cox proportional hazards. Results: A total of 108 patients were identified. Median follow-up was 18.0 months. One- and two-year OS were 79% and 61%, respectively. On MVA, gross tumor volume (GTV) ≥98.6 cm 3 [hazard ratio (HR): 2.11, 95% confidence interval (CI): 1.15–3.93, P=0.02] and female gender (HR: 2.01, 95% CI: 1.09–3.73, P=0.03) predicted for worse survival. Twelve patients (11%) developed ≥ grade 3 cardiac events. One- and two-year freedom from cardiac events (FFCE) was 94% and 84% respectively. On MVA, heart V5 ≥49% predicted for cardiac events (HR: 11.44, 95% CI: 1.31–111.60, P=0.03) while female gender was nearly significant (HR: 3.49, 95% CI: 0.97–16.80, P=0.06). Females presented with similar comorbidity scores, GTVs, and relapse rates but experienced higher heart doses than their male counterparts. Conclusions: Heart V5 ≥49% predicted for cardiac events after chemoradiation. However, cardiac dosimetry was not associated with survival. Rather, female gender and GTV ≥98.6 cm 3 led to worse survival. This study corroborates emerging data that low-dose radiation to the heart impacts cardiac toxicity.

RAD51 is the central protein in homologous recombination (HR) repair, where it first binds ssDNA and then catalyzes strand invasion via a D-loop intermediate. Additionally, RAD51 plays a role in faithful DNA replication by protecting stalled replication forks; this requires RAD51 to bind DNA but may not require the strand invasion activity of RAD51. We previously described a small-molecule inhibitor of RAD51 named RI(dl)-2 (RAD51 inhibitor of D-loop formation #2, hereafter called 2 h), which inhibits D-loop activity while sparing ssDNA binding. However, 2 h is limited in its ability to inhibit HR in vivo, preventing only about 50 % of total HR events in cells. We sought to improve upon this by performing a structure-activity relationship (SAR) campaign for more potent analogues of 2 h. Most compounds were prepared from 1-(2-aminophenyl)pyrroles by forming the quinoxaline moiety either by condensation with aldehydes, then dehydrogenation of the resulting 4,5-dihydro intermediates, or by condensation with N,N'-carbonyldiimidazole, chlorination, and installation of the 4-substituent through Suzuki-Miyaura coupling. Many analogues exhibited enhanced activity against human RAD51, but in several of these compounds the increased inhibition was due to the introduction of dsDNA intercalation activity. We developed a sensitive assay to measure dsDNA intercalation, and identified two analogues of 2 h that promote complete HR inhibition in cells while exerting minimal intercalation activity.

Maternal embryonic leucine zipper kinase (MELK) activates pathways that mediate aggressive tumor growth and therapy resistance in many types of adult cancers. Pharmacologic and genomic inhibition of MELK impairs tumor growth and increases sensitivity to radiation and chemotherapy. On the basis of these promising preclinical studies, early-phase adult clinical trials testing the MELK inhibitor OTS167 are ongoing. To investigate whether MELK is also a therapeutic target in neuroblastoma, we analyzed MELK expression in primary tumors and cell lines, and examined the effects of OTS167 on neuroblastoma growth. In primary tumors, high levels of MELK were associated with advanced stage disease and inferior survival. Higher levels of MELK were also detected in tumorigenic versus nontumorigenic neuroblastoma cell lines, and cells with higher levels of MELK expression were more sensitive to OTS167 than low-MELK expressing cells. OTS167 suppressed the growth of neuroblastoma xenografts, and in a preclinical model of minimal residual disease, survival was prolonged with MELK inhibition. OTS167 treatment downregulated MELK and its target enhancer of zeste homolog 2 (EZH2), a component of the polycomb repressive complex 2 (PRC2) that is known to modulate the DNA damage response. We also show that OTS167 reduced the formation of collapsed replication forks induced by camptothecin or radiation. Taken together, our results indicate that MELK indirectly mediates efficient processing of replication-associated DNA lesions in neuroblastoma, and that OTS167 sensitizes cells to DNA-damaging agents by abrogating this process. Further studies evaluating the activity of combination treatment regimens with OTS167 in neuroblastoma are warranted.

BackgroundCumulative evidences suggested the addition of platinum agents as neoadjuvant chemotherapy (NACT) could improve pathologic complete response (pCR) in triple-negative breast cancers (TNBC). Previous studies showed DNA homologous recombination deficiency (HRD) was a potential biomarker predicting pCR in ER-negative breast cancer. It would be helpful to personalize the use of platinum agents if a predictive biomarker for platinum sensitivity could be developed. Therefore, we tried to develop a HRD gene expression score to predict tumor sensitivity to platinum-based NACT in TNBC.MethodsA retrospective cohort of 127 TNBC patients from 2012 to 2017 was included in this study. All of them were diagnosed and received platinum-based NACT in Fudan University Shanghai Cancer Center. Clinical data and pathological data of the patients were collected and reviewed. By using quantitative reverse transcription-polymerase chain reaction (qRT-PCR), the expression level of eight HRD associated genes was analyzed from the formalin-fixed paraffin-embedded core needle biopsy samples which obtained before NACT. A random forest model was built to estimate the weight of each gene expression level and clinical-pathological factors. Samples were randomized into the training set and validation set with different splitting percentage from 50%:50% to 90%:10%. The training set was used to modulate parameters and select the best model using 5-fold cross validation. The performance of the final model was evaluated in the validation set. ResultsA 4-gene (BRCA1, XRCC5, PARP1, RAD51) expression signature scoring system was developed. TNBC with higher score had nearly quadruple likelihood to achieve pCR to platinum-based NACT compared with a lower score [odds ratio (OR)=3.878; PConclusionThe qRT-PCR-based 4-gene score can be used as an effective predictor of pCR to platinum-based NACT in TNBC.

Purpose: Molecular-based cancer tests have been developed to augment the standard clinical and pathologic features used to tailor treatments to individual breast cancer patients. Homologous recombination (HR) repairs double-stranded DNA breaks and promotes tolerance to lesions that disrupt DNA replication. Recombination Proficiency Score (RPS) quantifies HR efficiency based on the expression of four genes involved in DNA damage repair. We hypothesized low RPS values can identify HR-deficient breast cancers most sensitive to DNA-damaging chemotherapy. Experimental Design: We collected pathologic tumor responses and tumor gene expression values for breast cancer patients that were prospectively enrolled on clinical trials involving preoperative chemotherapy followed by surgery (N = 513). We developed an algorithm to calculate breast cancer–specific RPS (RPSb) values on an individual sample basis. Results: Low RPSb tumors are approximately twice as likely to exhibit a complete pathologic response or minimal residual disease to preoperative anthracycline-based chemotherapy as compared with high RPSb tumors. Basal, HER2-enriched, and luminal B breast cancer subtypes exhibit low RPSb values. In addition, RPSb predicts treatment responsiveness after controlling for clinical and pathologic features, as well as intrinsic breast subtype. Conclusions: Overall, our findings indicate that low RPS breast cancers exhibit aggressive features at baseline, but they have heightened sensitivity to DNA-damaging chemotherapy. Low RPSb values in basal, HER2-enriched, and luminal B subtypes provide a mechanistic explanation for their clinical behaviors and genomic instability. RPSb augments standard clinical and pathologic features used to tailor treatments, thereby enabling more personalized treatment strategies for individual breast cancer patients. Clin Cancer Res; 23(15); 4493–500. ©2017 AACR.

CASE Heterotopic ossification (HO) is a pathological formation of bone in nonosseous tissue and is a common complication of orthopaedic procedures. Radiotherapy is often used to prevent HO despite the small risk of secondary malignancy. Here, we report a case of a patient who developed a periprosthetic, radiation-induced sarcoma after delivery of a single fraction of 7 Gy for HO prophylaxis. This sarcoma was found to lie entirely within the treatment field and occurred within 5 years of radiation. CONCLUSION Appropriate counseling regarding radiation-induced sarcoma formation should be provided to patients considering radiotherapy for this HO prophylaxis.

Most pediatric head and neck cancers are treated with radiotherapy, but the morbidity associated with radiotherapy has become a prominent issue. This article discusses the common long-term complications associated with head and neck radiotherapy for childhood cancers. It reviews approaches to minimize toxicity and details the toxicities that head and neck radiation inflicts on relevant functional measures. In addition, it discusses the risk of radiation-induced secondary cancers in childhood cancer survivors, as well as strategies to reduce them. Thus, this article addresses approaches to minimize long-term radiation toxicities in order to improve the quality of life for childhood cancer survivors.

Innovation and progress in radiation oncology depend on discovery and insights realized through research in radiation biology. Radiobiology research has led to fundamental scientific insights, from the discovery of stem/progenitor cells to the definition of signal transduction pathways activated by ionizing radiation that are now recognized as integral to the DNA damage response (DDR). Radiobiological discoveries are guiding clinical trials that test radiation therapy combined with inhibitors of the DDR kinases DNA-dependent protein kinase (DNA-PK), ataxia telangiectasia mutated (ATM), ataxia telangiectasia related (ATR), and immune or cell cycle checkpoint inhibitors. To maintain scientific and clinical relevance, the field of radiation biology must overcome challenges in research workforce, training, and funding. The National Cancer Institute convened a workshop to discuss the role of radiobiology research and radiation biologists in the future scientific enterprise. Here, we review the discussions of current radiation oncology research approaches and areas of scientific focus considered important for rapid progress in radiation sciences and the continued contribution of radiobiology to radiation oncology and the broader biomedical research community.

Background In this study we sought to determine if staging endoscopic bronchial ultrasound (EBUS) improves outcomes in stage I non–small-cell lung cancer (NSCLC) patients who received hypofractionated radiation therapy (HFRT). Patients and Methods Patients with stage I NSCLC treated with HFRT from 2008 to 2015 were retrospectively identified from 3 affiliated institutions. All patients underwent positron emission tomography/computed tomography staging and a subset of patients received pretreatment EBUS. Patients with and without pre-radiation therapy EBUS were compared for baseline characteristics. The log rank test was used to compare Kaplan–Meier estimates. Univariate analysis (UVA) and multivariable analysis (MVA) were used to analyze the effect of factors on disease-free survival (DFS) and overall survival (OS). Results Ninety-two patients met study criteria. Median follow-up for the entire cohort was 21 months. Two-year DFS and OS were 63% and 81%, respectively. Two-year freedom from local, regional, and distant failure were 93%, 87%, and 87%, respectively. Thirty-seven of 92 patients (40%) received pretreatment EBUS. There were no statistically significant differences in 2-year freedom from regional failure rates, DFS, or OS for EBUS-staged versus non–EBUS-staged patients. On UVA, smaller tumor size (P = .03) and higher performance status (P = .05) were associated with improved OS. On MVA, tumor size retained significance for improved OS (hazard ratio [HR], 0.44; 95% confidence interval [CI], 0.19-0.97; P = .04) and higher performance status showed a trend toward improved OS (HR, 0.51; 95% CI, 0.23-1.11; P = .09). Conclusion In this retrospective series, we did not detect a difference in regional failure or survival outcomes among stage I NSCLC patients who received invasive staging with EBUS before HFRT.

INTRODUCTION: Literature concerning primary pulmonary sarcomas (PPS) is limited to small case series. This study examines, in a large cohort, the clinical characteristics and therapeutic strategies of PPS and their impact on overall survival (OS). METHODS: This was a retrospective analysis from the Surveillance, Epidemiology, and End Results database (1988-2008). Eligible patients had primary PPS and underwent local therapy. Survival estimates were obtained using the Kaplan-Meier method and the Cox regression model. OS of PPS patients were compared with a cohort of 10,909 patients with extremity soft-tissue sarcomas. RESULTS: The cohort included 365 PPS patients with a median follow-up of 21 months. Fifty-five percent of the patients had large tumors (>5 cm), 76% were high-grade, and 16% had node-positive disease. Seventy-five percent of the cohort underwent surgery alone, 14% underwent surgery and radiation therapy, and 11% underwent radiation therapy alone. Multivariate analysis showed reduced OS for patients with tumors more than 5 cm (hazard ratio [HR] 1.6, 95% confidence interval [CI] 1.25-2.19), high tumor grade (HR 3.1, 95% CI 1.26-3.62), and unresectable disease (HR 2.6, 95% CI 1.76-3.88. The 5-year OS for the cohort of pulmonary sarcomas versus sarcomas of the extremities was 35% versus 71% (p < 0.0001). CONCLUSION: This large study examining PPS patients reveals a high rate of nodal involvement and a markedly worse OS than patients with extremity soft-tissue sarcomas. Thus, given the poor overall prognosis, it is recommended that PPS patients undergo a thorough mediastinal nodal evaluation to rule out locoregional metastasis and proceed with aggressive treatment.

Homologous recombination (HR) is an evolutionarily conserved DNA repair process. Overexpression of the key HR protein RAD51 is a common feature of malignant cells. RAD51 plays two distinct genome-stabilizing roles, including HR-mediated repair of double-strand breaks (DSBs) and the promotion of replication fork stability during replication stress. Because upregulation of RAD51 in cancer cells can promote tumor resistance to DNA-damaging oncologic therapies, we and others have worked to develop cancer therapeutics that target various aspects of RAD51 protein function. Herein, we provide an overview of recent developments in this field, together with our perspectives on the challenges associated with these evolving anticancer strategies.

RAD51 is the central protein in homologous recombination (HR) DNA repair and represents a therapeutic target in oncology. Herein we report a novel class of RAD51 inhibitors that were identified by high throughput screening. In contrast to many previously reported RAD51 inhibitors, our lead compound 1 is capable of blocking RAD51-mediated D-loop formation (IC50 21.3 ± 7.8 μM) at concentrations that do not influence RAD51 binding to ssDNA. In human cells, 1 inhibits HR (IC50 13.1 ± 1.6 μM) without blocking RAD51's ability to assemble into subnuclear foci at sites of DNA damage. We determined that the active constituent of 1 is actually an oxidized derivative (termed RI(dl)-1 or 8) of the original screening compound. Our SAR campaign also yielded RI(dl)-2 (hereafter termed 9h), which effectively blocks RAD51's D-loop activity in biochemical systems (IC50 11.1 ± 1.3 μM) and inhibits HR activity in human cells (IC50 3.0 ± 1.8 μM).

Symptomatic retinal arterial macroaneurysms (RAM) are primarily investigated by fundus fluorescein angiography after presenting with visual disturbance. The natural history includes spontaneous regression and occasionally occlusion of the arteriole distal to the aneurysm. RAM may be managed conservatively. Interventional treatment options include focal argon laser photocoagulation, Nd:YAG laser hyaloidotomy, and pars plana vitrectomy. The purpose of this study was to elicit the rates of distal vessel occlusion and aneurysm thrombosis in RAM at presentation, and their relevance to the treatment of RAM. Furthermore, visual outcomes were examined. Retrospective review of cases of RAM presenting to a tertiary ophthalmology care centre was accomplished in a university teaching hospital. The angiographic features, treatment indications, and visual outcomes in patients with RAM were recorded. Angiographic features noted were distal vessel patency and aneurysm thrombosis at presentation. Ten patients with RAM were identified. Ninety percent had an angiographically patent distal arteriole, with 40 % showing spontaneous thrombosis of the aneurysm sac at presentation. Patients presenting with a spontaneously thrombosed RAM were managed conservatively, those with flow within the aneurysm wall were treated with focal laser, and those with subhyaloid haemorrhage underwent Nd:YAG laser hyaloidotomy. LogMAR visual acuity improved from 0.3 (±0) at presentation to 0.15 (±0.1) in the conservative group, and from 0.78 (±0.23) to 0.24 (±0.18) in those who underwent one intervention. One patient lost vision after multiple RAM. Thrombosis within the aneurysm wall is an important feature in deciding to treat RAM, and selective use of interventions improves vision in affected patients.

Homologous recombination (HR) is an essential process in cells that provides repair of DNA double-strand breaks and lesions that block DNA replication. RAD51 is an evolutionarily conserved protein that is central to HR. Overexpression of RAD51 protein is common in cancer cells and represents a potential therapeutic target in oncology. We previously described a chemical inhibitor of RAD51, called RI-1 (referred to as compound 1 in this report). The chloromaleimide group of this compound is thought to act as a Michael acceptor and react with the thiol group on C319 of RAD51, using a conjugate addition-elimination mechanism. In order to reduce the likelihood of off-target effects and to improve compound stability in biological systems, we developed an analogue of compound 1 that lacks maleimide-based reactivity but retains RAD51 inhibitory activity. This compound, 1-(3,4-dichlorophenyl)-3-(4-methoxyphenyl)-4-morpholino-1H-pyrrole-2,5-dione, named RI-2 (referred to as compound 7a in this report), appears to bind reversibly to the same site on the RAD51 protein as does compound 1. Like compound 1, compound 7a specifically inhibits HR repair in human cells.

Introduction: Outcomes data treating patients with oligometastatic (⩽5 metastases) non-small cell lung carcinoma (NSCLC) with hypofractionated image-guided radiotherapy (HIGRT) are limited. Methods: Consecutive oligometastatic NSCLC patients were reviewed from a prospective database. Patients were included if all active diseases were treated with HIGRT. Lesions that had received prior radiation or had radiographic/metabolic resolution after chemotherapy were not treated with HIGRT. Local control of all treated lesions, distant control, progression-free survival (PFS), overall survival (OS), and control of individual lesions (LeC) were calculated. Results: Twenty-five patients with median of 2 treated oligometastatic lesions were included. Median follow-up was 14 months. Median age was 66 years. Nineteen patients received systemic therapy before HIGRT and 11 had progressive disease after their most recent systemic therapy before HIGRT. Median OS and PFS were 22.7 and 7.6 months. The 18 months local control, distant control, OS, and PFS were 66.1%, 31.7%, 52.9%, and 28.0%. Greater than two sites treated with HIGRT, nonadenocarcinoma histology, prior systemic therapy, and progression after systemic therapy were associated with worse PFS. Sixty-two individual lesions of median size 2.7 cm were treated. For extracranial lesions, median total and fraction dose were 50 and 5 Gy. Median standard equivalent dose in 2 Gy fractions for extracranial lesions was 64.6 Gy yielding 18 months LeC of 70.7%. Standard equivalent dose ≥64.6 Gy increased LeC ( p = 0.04). Two patients experienced grade 3 toxicity. Conclusions: HIGRT for oligometastatic NSCLC provides durable LeC and may provide long-term PFS in some patients. Future HIGRT studies should optimize patient selection and integration with systemic therapy.

Stable HIV-1 replication requires the DNA repair of the integration locus catalyzed by cellular factors. The human RAD51 (hRAD51) protein plays a major role in homologous recombination (HR) DNA repair and was previously shown to interact with HIV-1 integrase (IN) and inhibit its activity. Here we determined the molecular mechanism of inhibition of IN. Our standard in vitro integration assays performed under various conditions promoting or inhibiting hRAD51 activity demonstrated that the formation of an active hRAD51 nucleofilament is required for optimal inhibition involving an IN-DNA complex dissociation mechanism. Furthermore we show that this inhibition mechanism can be promoted in HIV-1-infected cells by chemical stimulation of the endogenous hRAD51 protein. This hRAD51 stimulation induced both an enhancement of the endogenous DNA repair process and the inhibition of the integration step. Elucidation of this molecular mechanism leading to the restriction of viral proliferation paves the way to a new concept of antiretroviral therapy based on the enhancement of endogenous hRAD51 recombination activity and highlights the functional interaction between HIV-1 IN and hRAD51.

Introduction Treatment of technically operable, medically fit locoregionally advanced non-small cell lung cancer (NSCLC) patients is a controversial therapeutic challenge. Our group routinely uses a trimodality approach. Recent advances in radiotherapy allow for improved tumor targeting and daily patient positioning. We hypothesized that these technologies would improve pathologic response rates. We analyzed consecutively treated stage IIIA/IIIB NSCLC patients undergoing chemoradiotherapy before major lung resection, with particular attention paid to the impact of advanced technologies. Methods Locoregionally advanced NSCLC patients (N2) staged in a multidisciplinary forum with mediastinoscopy were planned to receive platinum-based chemotherapy and 60 Gy and major lung resection. Four-dimensional CT (4DCT) and image-guided radiotherapy (IGRT) were used as available. Survival endpoints were estimated using the Kaplan–Meier method and compared using the log-rank test. Multivariate analysis was performed using Cox proportional hazards models. Results We identified 53 patients from 2/1999 to 2/2010. Median RT dose was 59 Gy. 68% underwent lobectomy. Forty-three patients were downstaged pathologically (81%), 38 experienced mediastinal sterilization (72%), and 21 (40%) had complete pathologic response (pCR). 1 and 2 year OS were 85.5% and 61.6%. Superior OS and DFS were associated with nodal downstaging and mediastinal sterilization (pN0). Treatment with IGRT/4DCT in 10 patients resulted in high rates of nodal downstaging (100% vs 77%, p = 0.0452), mediastinal sterilization (90% vs 67%, p = 0.0769), and pCR (60% vs 35%, p = 0.0728). Conclusions In selected patients, definitive dose CRT followed by major lung resection results in promising DFS and OS. The use of advanced radiotherapy techniques (4DCT and IGRT) appears to result in promising pathologic response rates.

RAD51 and other members of the RecA family of strand exchange proteins assemble on ssDNA to form presynaptic filaments, which carry out the central steps of homologous recombination. A microplate-based assay was developed for high-throughput measurement of hRAD51 filament formation on ssDNA. With this method, a 10,000 compound library was screened, leading to the identification of a small molecule (RS-1) that enhances hRAD51 binding in a wide range of biochemical conditions. Salt titration experiments showed that RS-1 can enhance filament stability. Ultrastructural analysis of filaments formed on ssDNA showed that RS-1 can increase both protein–DNA complex lengths and the pitch of helical filament turns. RS-1 stimulated hRAD51-mediated homologous strand assimilation (D-loop) activity by at least 5- to 11-fold, depending on the condition. This D-loop stimulation occurred even in the presence of Ca 2+ or adenylyl-imidodiphosphate, indicating that the mechanism of stimulation was distinct from that conferred by Ca 2+ and/or inhibition of ATPase. No D-loop activity was observed in the absence of a nucleotide triphosphate cofactor, indicating that the compound does not substitute for this requirement. These results indicate that RS-1 enhances the homologous recombination activity of hRAD51 by promoting the formation of active presynaptic filaments. Cell survival assays in normal neonatal human dermal fibroblasts demonstrated that RS-1 promotes a dose-dependent resistance to the cross-linking chemotherapeutic drug cisplatin. Given that RAD51-dependent recombination is a major determinant of cisplatin resistance, RS-1 seems to function in vivo to stimulate homologous recombination repair proficiency. RS-1 has many potential applications in both research and medical settings.

Radiotherapy plays a central role in the treatment of pediatric brain tumors. Historically, surgical resection alone was the mainstay of treatment for pediatric CNS malignancies. During the past 75 years, radiotherapy has been incorporated into the upfront treatment of many pediatric brain tumors either as adjuvant therapy for resected tumors, definitive treatment for unresectable malignancies or as prophylactic therapy for occult microscopic disease. Many CNS malignancies, which were once universally fatal are now curable with multimodality approaches that integrate surgery, chemotherapy and radiotherapy. Unfortunately, the long-term CNS side effects of radiotherapy remain a major obstacle for survivors of childhood tumors. In this article we will discuss these issues in detail and summarize the ongoing efforts to reduce the risks of these toxicities.

For locally advanced but technically operable nonsmall cell lung cancer (NSCLC), neoadjuvant chemoradiotherapy is frequently used. Ideal radiotherapy dose in this context is unclear.Twenty-six NSCLC patients with N2 disease were retrospectively reviewed. All received preoperative concurrent platinum-based chemoradiotherapy. Gross tumor volumes received a median of 58 Gy (range, 50-60 Gy).Two patients experienced major complications and died, resulting in a postoperative mortality rate of 7.7%. Three patients (11.5%) had minor complications. Pathologic specimens revealed downstaging in 76.9% of patients. The pathologic complete response (CR) rate was 34.6%. Downstaging of nodes was observed in 20 of 26 patients. With a median follow-up of 18.3 months, the 1- and 3-year actuarial survival rates were 80.2% and 45.7%, respectively. The 1- and 3-year actuarial disease-free survival (DFS) rates were 76.9% and 37.3%, respectively. Patients experiencing mediastinal downstaging had better DFS rates, relative to patients that did not (18-month DFS = 79.2% vs. 0%; P = 0.0001). Differences in RT dose (50-60 Gy) and types of chemotherapeutic regimens did not significantly impact pathologic downstaging rates, CR rates, DFS, or survival.Neoadjuvant chemotherapy with high-dose concurrent RT is well tolerated and results in favorable outcomes.

Purpose: The primary objective of this phase I study was to determine the maximum tolerated dose for pemetrexed, alone and in combination with carboplatin, with concurrent radiotherapy.Experimental Design: Patients with locally advanced or metastatic non–small cell lung cancer (NSCLC) or esophageal cancer were treated every 21 days for two cycles. Regimen 1 was pemetrexed (200-600 mg/m2); regimen 2 was pemetrexed (500 mg/m2) with escalating carboplatin doses (AUC = 4-6). Both regimens included concurrent radiation (40-66 Gy; palliative-intent doses were lower).Results: Thirty patients (18 locally advanced and 12 metastatic with dominant local symptoms) were enrolled, with an Eastern Cooperative Oncology Group performance status of 0/1/2 (n = 8/21/1). All dose levels were tolerable for regimen 1 (n = 18: 15 NSCLC and 3 esophageal cancers) and regimen 2 (n = 12: all NSCLC). In regimen 1, one dose-limiting toxicity (grade 4 esophagitis/anorexia) occurred (500 mg/m2). Grade 3 neutropenia (3 of 18 patients) was the main hematologic toxicity. In regimen 2, one dose-limiting toxicity (grade 3 esophagitis) occurred (500 mg/m2; AUC = 6); grade 3/4 leukopenia (4 of 12 patients) was the main hematologic toxicity. Four complete responses (2 pathology proven) and eight partial responses were observed. When systemically active chemotherapy doses were reached, further dose escalation was discontinued, and a phase II dose-range was established (pemetrexed 500 mg/m2 and carboplatin AUC = 5-6).Conclusions: The combination of pemetrexed (500 mg/m2) and carboplatin (AUC = 5 or 6) with concurrent radiation is well tolerated, allows for the administration of systemically active chemotherapy doses, and shows signs of activity. To further determine efficacy, safety profile, and optimal dosing, the Cancer and Leukemia Group B study 30407 is currently evaluating this regimen in patients with unresectable stage III NSCLC.

DNA repair via the homologous recombination pathway requires the recombinase RAD51 and, in vertabrates, five RAD51 paralogs. The paralogs form two complexes in solution, a XRCC3/RAD51C heterodimer and a RAD51B/RAD51C/RAD51D/XRCC2 heterotetramer. Mutation of any one of the five paralog genes prevents subnuclear assembly of recombinase at damaged sites and renders cells 30–100 fold sensitive to DNA cross-linking drugs. Phage display was used to isolate peptides that bind the paralog XRCC3. Sequences of binding peptides showed similarity to residues 14–25 of RAD51C protein. Point mutations in this region of RAD51C altered its interaction with both XRCC3 and RAD51B in a two-hybrid system. A synthetic peptide composed of residues 14–25 of RAD51C fused to a membrane transduction sequence [protein transduction domain 4 (PTD4)], inhibited subnuclear assembly of RAD51 recombinase, and sensitized Chinese hamster ovary cells to cisplatin when added to growth medium. These results suggest that residues 14–25 of RAD51C contribute to a “hot spot” used in both XRCC3-RAD51C and RAD51B-RAD51C interactions. Peptide-based inhibition of homologous recombination may prove useful for improving the efficacy of existing cancer therapies.

RAD51 plays a central role in homologous recombination (HR), which maintains genome integrity. RAD51 is commonly overexpressed in cancer cells relative to normal tissue and is considered a therapeutic target in oncology. One potential challenge for targeting RAD51 pharmacologically is that it mediates functions in both double-strand DNA break (DSB) repair and stabilization of stalled replication forks. In order to distinguish compound-mediated effects on these RAD51 functions, we developed a novel class of RAD51 inhibitors. In contrast to many previously reported RAD51 inhibitors, we sought to develop compounds that do not inhibit RAD51's ability to bind single-stranded DNA (ssDNA). Instead, these compounds prevent RAD51-ssDNA nucleoprotein filaments from invading into homologous double-stranded DNA templates and forming D-loops. Our initial lead compound RI(dl)-1 (an abbreviation for RAD51 inhibitor of D-loop formation #1) is capable of blocking RAD51-mediated D-loop formation in biochemical assays, using concentrations that do not prevent RAD51 binding to ssDNA. An analog of this compound, termed RI(dl)-2, provides even better inhibition of RAD51's D-loop activity in biochemical systems (IC50 15.8 µM). RI(dl)-2 reduces HR activity in cells in dose ranges that do not stimulate single strand annealing (SSA) activity, which distinguishes it more generalized RAD51 inhibitors. RI(dl)-2 also sensitizes several cancer cell lines to radiation-induced death. We now present the results of more extensive structure activity relationship (SAR) optimizations aimed at further improving the potency and selectivity of this class of compounds. Several of these compounds are capable of delaying the timely resolution of radiation-induced RAD51 foci, even though initial RAD51 foci are apparently normal at earlier time points. Similar focus kinetics are observed for gamma-H2AX in identically treated cells, supporting the interpretation that these compounds permit RAD51 assembly at DSBs but prevent the completion of DSB repair. Unlike RI(dl)-2, some these newer compounds sensitize cancer cells to mitomycin C. These specialized RAD51 inhibitory compounds are attractive candidates for potential use as radiation or chemotherapy sensitizers, since they may exert fewer toxic risks compared to more generalized inhibitors of the HR repair machinery. They may also serve to help distinguish the functions of RAD51 DSB repair and replication stress tolerance, which may enable better understanding of RAD51's roles in maintaining genome stability. This abstract is also being presented as Poster A02. Citation Format: Brian Budke, Wei Lv, Werner Tueckmantel, Alan Kozikowski, Philip Connell. Small molecules that specifically inhibit the D-loop activity of RAD51 [abstract]. In: Proceedings of the AACR Special Conference on DNA Repair: Tumor Development and Therapeutic Response; 2016 Nov 2-5; Montreal, QC, Canada. Philadelphia (PA): AACR; Mol Cancer Res 2017;15(4_Suppl):Abstract nr PR02.

A recent study challenges the view that radiation-induced apoptosis is beneficial in tumor therapy by showing that caspase 3–mediated apoptosis in response to ionizing radiation activates a growth signaling cascade in tumor cells, thereby stimulating tumor repopulation (pages 860–866). These results may have important implications for the clinical use of radiotherapy or chemotherapy to induce apoptosis in tumors.

RAD51 is the central protein that catalyzes DNA repair via homologous recombination, a process that ensures genomic stability. RAD51 protein is commonly expressed at high levels in cancer cells relative to their noncancerous precursors. High levels of RAD51 expression can lead to the formation of genotoxic RAD51 protein complexes on undamaged chromatin. We developed a therapeutic approach that exploits this potentially toxic feature of malignancy, using compounds that stimulate the DNA-binding activity of RAD51 to promote cancer cell death. A panel of immortalized cell lines was challenged with the RAD51-stimulatory compound RS-1. Resistance to RS-1 tended to occur in cells with higher levels of RAD54L and RAD54B, which are Swi2/Snf2-related translocases known to dissociate RAD51 filaments from dsDNA. In PC3 prostate cancer cells, RS-1–induced lethality was accompanied by the formation of microscopically visible RAD51 nuclear protein foci occurring in the absence of any DNA-damaging treatment. Treatment with RS-1 promoted significant antitumor responses in a mouse model, providing proof-of-principle for this novel therapeutic strategy. Cancer Res; 74(13); 3546–55. ©2014 AACR.

Mutagenesis is a hallmark of malignancy, and many oncologic treatments function by generating additional DNA damage. Therefore, DNA damage repair is centrally important in both carcinogenesis and cancer treatment. Homologous recombination (HR) and nonhomologous end joining are alternative pathways of double-strand DNA break repair. We developed a method to quantify the efficiency of DNA repair pathways in the context of cancer therapy. The recombination proficiency score (RPS) is based on the expression levels for four genes involved in DNA repair pathway preference (Rif1, PARI, RAD51, and Ku80), such that high expression of these genes yields a low RPS. Carcinoma cells with low RPS exhibit HR suppression and frequent DNA copy number alterations, which are characteristic of error-prone repair processes that arise in HR-deficient backgrounds. The RPS system was clinically validated in patients with breast or non-small cell lung carcinomas (NSCLCs). Tumors with low RPS were associated with greater mutagenesis, adverse clinical features, and inferior patient survival rates, suggesting that HR suppression contributes to the genomic instability that fuels malignant progression. This adverse prognosis associated with low RPS was diminished if NSCLC patients received adjuvant chemotherapy, suggesting that HR suppression and associated sensitivity to platinum-based drugs counteract the adverse prognosis associated with low RPS. Therefore, RPS may help oncologists select which therapies will be effective for individual patients, thereby enabling more personalized care.

Objective. The goal of this work was to evaluate the outcome of endometrial carcinoma patients undergoing primary surgery who have serosal involvement (SI). Methods. Between 1980 and 1998, 562 women underwent primary surgery for endometrial cancer at the University of Chicago. Thirty-nine were noted to have SI. FIGO stages were IIIA (19), IIIB (1), IIIC (7), and IV (12). Of the 19 IIIA patients, 15 had solitary SI. Twenty-six patients received pelvic radiation therapy (RT) with or without vaginal brachytherapy (VB). One patient received whole-abdomen radiation therapy, and 13, adjuvant chemotherapy. Solitary SI patients received pelvic RT with or without VB as their sole adjuvant therapy. Disease-free survivals (DFSs) were estimated using the method of Kaplan and Meier and prognostic factors were analyzed by the log-rank test. Results. With a median follow-up of 30.3 months, the 5-year actuarial DFS of the entire group was 28.9%. Factors correlated with disease recurrence included tumor stage ( P = 0.003) and lymph node involvement ( P = 0.04). In addition, patients with solitary SI had a better 5-year DFS (41.5% vs 20%, P = 0.04) than patients with SI plus other extrauterine sites. Relapse occurred in 23 women overall and in 7 of 15 solitary SI patients. The most common site of disease recurrence was distant both in the entire group and in the solitary SI patients. While abdominal recurrences were common in the entire group, they were infrequent in solitary SI patients. Conclusion. Endometrial carcinoma patients with SI have a high rate of relapse and a poor outcome. Even when patients have extrauterine disease limited to SI, the outcome is relatively unfavorable. Nonetheless, our results demonstrate the need to distinguish patients with solitary SI and those with SI plus other extrauterine disease sites.

The aim of this study was to evaluate age as a prognostic factor for recurrence in endometrial cancer patients treated with primary surgery.Between 1983 and 1998, 455 endometrial cancer patients underwent primary surgery at our institution. Patients were divided into three age groups based on age at diagnosis: Group A (age60, n = 156), B (age 60-69, n = 147), and C (age/=70, n = 152). Clinicopathologic, treatment factors, and outcome were compared among the three groups. Prognostic factors were evaluated by univariate and multivariate analysis.The three age groups had a similar distribution of most pathologic features including stage, histology, cervical involvement, positive cytology, adnexal involvement, nodal metastases, serosal involvement, and lymphovascular invasion (LVI). Older women had a higher rate, however, of deep (1/2) myometrial invasion (P0.0001) and grade 3 tumors (P0.0001). The extent of surgical staging and use of adjuvant radiation therapy were similar. Five-year disease-free survivals (DFS) of Groups A, B, and C were 74.3, 70.2, and 60.3%, respectively (P = 0.08). A significant difference in DFS was seen when Groups A and B were combined and compared with Group C (72.0 vs 60.3%, P = 0.03). Multivariate analysis confirmed the significance of race, stage, grade, and LVI. Age was not found to be associated with recurrence (HR 1.1, 95% C.I. 0.91-1.5, P = 0.21).Our results reveal that, in a large cohort of comparably staged and treated endometrial carcinoma patients, age is not a prognostic factor for recurrence.

Recent data have suggested that conventional pathologic features (myometrial invasion (MI), grade, stage) lose their prognostic significance following postoperative radiation therapy (RT) in Stage I–II endometrial carcinoma. Our goal was to test this finding in a large cohort of women treated at our institution. Between 1980 and 1997, 188 Stage I (140) and II (48) endometrial adenocarcinoma patients received postoperative RT. RT consisted of pelvic RT (112), vaginal brachytherapy (36), or both (40). Clinicopathologic factors were evaluated as prognostic factors on both univariate and multivariate analyses. Factors correlated with recurrence on univariate analysis included MI (P = 0.05), grade (P = 0.07), lymphovascular invasion (LVI) (P = 0.001) and stage (P = 0.03). Multivariate analysis confirmed the significance of grade (P = 0.02), LVI (P = 0.001), and stage (P = 0.02). Conventional pathologic features do not lose their prognostic significance in pathologic Stage I–II endometrial adenocarcinoma patients following postoperative RT. These factors should continue to be used to identify women at risk for recurrence despite adjuvant RT. New prognostic markers are needed to better identify high-risk patients. Int. J. Cancer (Radiat. Oncol. Invest.) 90, 224–230 (2000). © 2000 Wiley-Liss, Inc.

To estimate the incidence and severity of problems arising during the hospitalization of cervical carcinoma patients undergoing low-dose-rate intracavitary brachytherapy (ICB).One hundred seventy ICB implants in 128 cervical carcinoma patients undergoing curative radiation therapy were reviewed. All events during the hospitalization requiring physician evaluation and/or intervention were scored as a "problem" and divided into 10 categories (fever/infection, pain, gastrointestinal, renal, pulmonary, cardiac, dermatologic, gynecologic, endocrinologic, psychiatric). Problems were scored as mild (no significant morbidity, therapy not discontinued), moderate (therapy discontinued but no significant morbidity), or severe (significant morbidity or mortality). Patient and treatment factors were correlated with acute problems.Forty-two implants (24.7%) were associated with acute problems (95% minor, 5% moderate, 0% severe). The most common types were fever/infection (14.1%) and gastrointestinal problems (5. 9%). Other problem types occurred in3% of implants. No patient or treatment factor including age, comorbid disease, weight, implant duration, or anesthesia type was significantly correlated with acute problems. Patients who developed acute problems had a survival (P = 0.21) and risk of late sequelae (P = 0.74) similar to those of patients without acute problems.Problems occur during the hospitalization in approximately one-quarter of cervical carcinoma patients undergoing low-dose-rate ICB. However, most are minor and do not result in morbidity, require discontinuation of therapy, or adversely impact on outcome.