Generalization optimizing machine learning to improve CT scan radiomics and assess immune checkpoint inhibitors' response in non-small cell lung cancer: a multicenter cohort study

Background

Recent developments in artificial intelligence suggest that radiomics may represent a promising non-invasive biomarker to predict response to immune checkpoint inhibitors (ICIs). Nevertheless, validation of radiomics algorithms in independent cohorts remains a challenge due to variations in image acquisition and reconstruction. Using radiomics, we investigated the importance of scan normalization as part of a broader machine learning framework to enable model external generalizability to predict ICI response in non-small cell lung cancer (NSCLC) patients across different centers.

Methods

Radiomics features were extracted and compared from 642 advanced NSCLC patients on pre-ICI scans using established open-source PyRadiomics and a proprietary DeepRadiomics deep learning technology. The population was separated into two groups: a discovery cohort of 512 NSCLC patients from three academic centers and a validation cohort that included 130 NSCLC patients from a fourth center. We harmonized images to account for variations in reconstruction kernel, slice thicknesses, and device manufacturers. Multivariable models, evaluated using cross-validation, were used to estimate the predictive value of clinical variables, PD-L1 expression, and PyRadiomics or DeepRadiomics for progression-free survival at 6 months (PFS-6).

Results

The best prognostic factor for PFS-6, excluding radiomics features, was obtained with the combination of Clinical + PD-L1 expression (AUC = 0.66 in the discovery and 0.62 in the validation cohort). Without image harmonization, combining Clinical + PyRadiomics or DeepRadiomics delivered an AUC = 0.69 and 0.69, respectively, in the discovery cohort, but dropped to 0.57 and 0.52, in the validation cohort. This lack of generalizability was consistent with observations in principal component analysis clustered by CT scan parameters. Subsequently, image harmonization eliminated these clusters. The combination of Clinical + DeepRadiomics reached an AUC = 0.67 and 0.63 in the discovery and validation cohort, respectively. Conversely, the combination of Clinical + PyRadiomics failed generalizability validations, with AUC = 0.66 and 0.59.

Conclusion

We demonstrated that a risk prediction model combining Clinical + DeepRadiomics was generalizable following CT scan harmonization and machine learning generalization methods. These results had similar performances to routine oncology practice using Clinical + PD-L1. This study supports the strong potential of radiomics as a future non-invasive strategy to predict ICI response in advanced NSCLC.

Second-line treatment outcomes after progression from first-line chemotherapy plus immunotherapy in patients with advanced non-small cell lung cancer

INTRODUCTION

Chemotherapy plus immunotherapy is the standard of care for patients with metastatic NSCLC. No study has evaluated the outcomes of second-line chemotherapy treatments after progression following first-line chemo-immunotherapy.

METHOD

This multicenter retrospective study evaluated the efficacy of second line (2L) chemotherapies after progression under first-line (1L) chemo-immunotherapy, measured by overall survival (2L-OS) and progression free survival (2L-PFS).

RESULTS

A total of 124 patients were included. The mean age was 63.1 years, 30.6 % of the patients were female, 72.6 % had an adenocarcinoma and 43.5 % had a poor ECOG-performance status prior to 2L initiation. Sixty-four (52.0 %) patients were considered resistant to first line chemo-immunotherapy. (1L-PFS < 6 months). In 2L treatments, 57 (46.0 %) patients received taxane monotherapy, 25 (20.1 %) taxane plus anti-angiogenic, 12 (9.7 %) platinum-based chemotherapy and 30 (24.2 %) other chemotherapy. At a median follow-up of 8.3 months (95 %CI: 7.2-10.2), post initiation of 2L treatment, the median 2L-OS was 8.1 months (95 % CI: 6.4-12.7) and the median 2L-PFS was 2.9 months (95 %CI: 2.4-3.3). Overall, the 2L-objective response and 2L-disease control rates were 16.0 %, and 42.5 %, respectively. Taxane plus anti-angiogenic and platinum rechallenge achieved longest median 2L-OS: not reached (95 %CI: 5.8-NR) and 17.6 months (95 %CI 11.6-NR), respectively (p = 0.05). Patients resistant to the 1L treatment had inferior outcomes (2L-OS 5.1 months, 2L-PFS 2.3 months) compared with 1L responders (2L-OS 12.7 months, 2L-PFS 3.2 months).

CONCLUSION

In this real-life cohort, 2L chemotherapy achieved modest activity following progression under chemo-immunotherapy. 1L-resistant patients remained a refractory population, highlighting a need for new 2L strategies.

Neuronal GPR81 regulates developmental brain angiogenesis and promotes brain recovery after a hypoxic ischemic insult

Perinatal hypoxic/ischemic (HI) brain injury is a major clinical problem with devastating neurodevelopmental outcomes in neonates. During HI brain injury, dysregulated factor production contributes to microvascular impairment. Glycolysis-derived lactate accumulated during ischemia has been proposed to protect against ischemic injury, but its mechanism of action is poorly understood. Herein, we hypothesize that lactate via its G-protein coupled receptor (GPR81) controls postnatal brain angiogenesis and plays a protective role after HI injury. We show that GPR81 is predominantly expressed in neurons of the cerebral cortex and hippocampus. GPR81-null mice displayed a delay in cerebral microvascular development linked to reduced levels of various major angiogenic factors and augmented expression of anti-angiogenic Thrombospondin-1 (TSP-1) in comparison to their WT littermates. Coherently, lactate stimulation induced an increase in growth factors (VEGF, Ang1 and 2, PDGF) and reduced TSP-1 expression in neurons, which contributed to accelerating angiogenesis. HI injury in GPR81-null animals curtailed vascular density and consequently increased infarct size compared to changes seen in WT mice; conversely intracerebroventricular lactate injection increased vascular density and diminished infarct size in WT but not in GPR81-null mice. Collectively, we show that lactate acting via GPR81 participates in developmental brain angiogenesis, and attenuates HI injury by restoring compromised microvasculature.

Genomic Analysis of Tumors from Patients with Glioblastoma with Long-Term Response to Afatinib

Glioblastoma is an aggressive form of central nervous system tumor. Recurrence rates following primary therapy are high, and few second-line treatment options provide durable clinical benefit. Aberrations of the epidermal growth factor receptor (EGFR) gene are observed in up to 57% of glioblastoma cases and EGFR overexpression has been identified in approximately 60% of primary glioblastomas. In preclinical studies, afatinib, a second-generation ErbB blocker, inhibited cell proliferation in cells harboring mutations commonly found in glioblastoma. In two previous Phase I/II studies of afatinib plus temozolomide in patients with glioblastoma, limited efficacy was observed; however, there was notable benefit in patients with the EGFR variant III (EGFRvIII) mutation, EGFR amplification, and those with loss of phosphatase and tensin homolog (PTEN). This case series report details treatment histories of three long-term responders from these trials. Next-generation sequencing of tumor samples identified alterations in a number of cancer-related genes, including mutations in, and amplification of, EGFR. Tumor samples from all three patients shared favorable prognostic factors, eg O⁶-methylguanine-DNA methyl-transferase (MGMT) gene promoter methylation; however, negative prognostic factors were also observed, suggesting that these shared genetic features did not completely account for the favorable responses. The genetic profile of the tumor from Patient 1 showed clear differences from the other two tumors: lack of involvement of EGFR aberrations but with a mutation occurring in PTPN11. Preclinical studies showed that single-agent afatinib and temozolomide both separately inhibit the growth of tumors with a C-terminal EGFR truncation, thus providing further rationale for combining these two agents in the treatment of glioblastomas harboring EGFR aberrations. These findings suggest that afatinib may provide treatment benefit in patients with glioblastomas that harbor ErbB family aberrations and, potentially, other genetic aberrations. Further studies are needed to establish which patients with newly diagnosed/recurrent glioblastomas may potentially benefit from treatment with afatinib.

Population-based analysis of non-operative management and treatment patterns in older women with estrogen receptor-positive breast cancer

PURPOSE

To examine the proportion of older women with ER + HER2- breast cancer receiving non-operative management versus surgery, and to evaluate the use of axillary staging and adjuvant radiation in this population.

METHODS

We queried the SEER database to identify all women aged 70 years or older with stage I-III ER + HER2- invasive breast cancer diagnosed between 2010 and 2016. We evaluated trends in non-operative management, breast surgery, axillary staging, and adjuvant radiation according to age at diagnosis.

RESULTS

We identified 57,351 older women with ER + HER2- disease. Overall, 3538 (6.2%) of the cohort underwent non-operative management, 38,452 (67.0%) underwent breast-conserving surgery (BCS), and 15,361 (26.8%) underwent mastectomy. The proportion of patients undergoing non-operative management increased from 2.8% among 70-74-year-old women to 30.1% in those ≥ 90 years old (p < 0.001). In 53,813 women who underwent surgery, 36,850 (68.5%) underwent sentinel lymph node biopsy, while 10,861 (20.2%) underwent axillary lymph node dissection. Subgroup analysis of 29,032 older women undergoing BCS for stage I ER + HER2- breast cancer revealed a 14.2% rate of omission of axillary staging, increasing from 5.3% in those 70-74 years to 67.6% in those ≥ 90 years old (p < 0.001). Receipt of adjuvant radiation occurred in 63.3% of older women following BCS and 18% post-mastectomy, with similar trends towards omission in older age groups.

CONCLUSION

Primary breast surgery remains the dominant management strategy for the majority of older women with ER + HER2- breast cancer. Omission of axillary staging and adjuvant radiation are used in a minority of eligible women undergoing breast conservation for early-stage disease.

CTNI-05. NRG ONCOLOGY / RTOG 1119: PHASE II RANDOMIZED STUDY OF WHOLE BRAIN RADIOTHERAPY / STEREOTACTIC RADIOSURGERY WITH CONCURRENT LAPATINIB IN PATIENTS WITH BRAIN METASTASES FROM HER2-POSITIVE BREAST CANCER

Trastuzumab/pertuzumab improved outcomes for patients (pts) with HER2+ breast cancer. Increased survival coupled with limited blood-brain barrier (BBB) penetration of these agents apparently contributes to increased incidence of brain metastases (BM). Lapatinib (L) crosses the BBB and demonstrates activity against BM. Based upon pre/early clinical data, it’s hypothesized that L + whole brain radiotherapy (WBRT) or Stereotactic Radiosurgery (SRS) would improve intracranial control compared to WBRT/SRS (RT) alone. This randomized phase II trial included HER2+ breast cancer pts with ≥ 1 measurable, unirradiated parenchymal BM. Pts were randomized 1:1 to WBRT (37.5 Gy/3 weeks) or SRS +/- concurrent L (1000 mg dailyx6 weeks), andwere stratified by graded prognostic assessment (GPA), use of non-CNS penetrating anti-HER2 therapies, and previous SRS/resection. The primary endpoint was intracranial complete response (CR) rate 12weeks (wk) after RT. Secondary endpoints included objective response rate (ORR), lesion-specific response rate, CNS progression-free survival, and overall survival. 114 of 143 pts were evaluable for 12-wk CR (52 RT, 62 RT+L). Rate of grade 3 and 4 adverse events were 8% and 0% for RT and 29% and 6% for RT+L. 92% and 90% pts received concurrent and adjuvant L per protocol/acceptable variation. There were no significant differences in 12 or 4wk CR rates (p=0.97 and p=0.77); 5.8% and 0% at 12wk and 3.6% and 1.5% at 4wk for RT and RT+L, respectively. The ORR at 4 wk was 42% and 56% (p=0.059, RECIST), 40% and 58% (p=0.027, WHO) in the RT and RT+L, respectively. Although the addition of lapatinib to WBRT/SRS did not improve the 12wk CR rate, it showed meaningful clinical benefit by demonstrating a trend toward improvement of 4 wk ORR. Results of ongoing central review of MRIs using RECIST1.1, WHO and RANO-BM criteria including secondary endpointswill be reported. Support: NCI grants U10CA180868, U10CA180822, UG1CA189867, and Novartis

Oncologic Safety of Sentinel Lymph Node Biopsy Alone After Neoadjuvant Chemotherapy for Breast Cancer

BACKGROUND

The oncologic safety of sentinel lymph node biopsy (SLNB) alone for clinically node-positive (cN1-2) patients who convert to pathologic node-negativity (ypN0) after neoadjuvant chemotherapy (NAC) is not well established.

METHODS

This study retrospectively identified 244 consecutive patients with a diagnosis of cT1-3cN0-2 breast cancer who underwent NAC followed by SLNB at the authors' institution between 2013 and 2018. The patients were categorized as clinically node-negative (cN0) or cN1-2 before the onset of NAC, and the Kaplan-Meier method was used to compare locoregional and distant recurrence rates after SLNB alone for ypN0 patients.

RESULTS

Among 244 patients who underwent NAC followed by surgery with SLNB for axillary staging, 112 (45.9%) were cN0 at presentation, whereas 132 (54.5%) had biopsy-proven cN1-2 disease and converted to cN0 after treatment. Of the patients presenting with cN0 disease, 102 (91.1%) were ypN0 on SLNB pathology compared with 60 cN1/2 patients (45.5%; p < 0.001). Regional nodal irradiation was administered to 5% of the cN0/ypN0 patients compared with 70.7% of the cN1-2/ypN0 patients (p < 0.001). Overall, 211 patients were treated with SLNB alone and had a median follow-up period of 36 months (interquartile range [IQR], 24-53 months). For 101 cN0/ypN0 patients who underwent SLNB alone, the 5-year local and regional recurrence rates were respectively 5.7% (95% confidence interval [CI], 2.4-13.8) and 1% (95% CI 0.1-7.0). For 58 cN1-2/ypN0 patients who underwent SLNB alone, the 5-year local and regional recurrence rates were respectively 4.1% (95% CI 1.0-15.5) and 0%, with no axillary recurrences noted.

CONCLUSION

For ypN0 patients, SLNB alone after NAC is associated with low and acceptable short-term axillary recurrence rates. Additional follow-up data from prospective clinical trials are needed to confirm long-term oncologic safety and define optimal local therapy recommendations.

Breast cancer in women aged 80 years and older: Clinical characteristics and treatment patterns according to biologic subtype

e12594

Background: Older age is associated with poorer breast cancer-specific survival (BCSS) outcomes, despite a higher prevalence of biologically favorable disease. We sought to evaluate differences in the clinical characteristics and management of older women according to biologic subtype of breast cancer. Methods: The Surveillance, Epidemiology, and End Results (SEER) treatment database was queried to identify all women aged 80 years or older with a first diagnosis of invasive breast cancer between 2010 and 2016. Patients were subgrouped according to biologic subtype and clinical and treatment-related variables were compared. Multivariable logistic regression was then performed to determine factors independently associated with receipt of breast-conserving surgery (BCS) and adjuvant radiation. Results: Overall, 27,375 women with a median age of 84 (range, 80-108 years) met inclusion criteria. The majority of older women were diagnosed with HR+HER2- breast cancer (78.9%), followed by HER2+ (11.0%) and triple-negative breast cancer (TNBC) (10.0%). In women with stage I-III disease, non-operative management was employed in 13.4% of HR+HER2- patients, compared to 16.7% of HER2+ patients and 11.0% of TNBC (p < 0.001). In those undergoing surgery, BCS was most common in HR+HER2- patients (80.9%), compared to HER2+ (68.9%) and TNBC (67.8%; p < 0.001). Axillary surgery was performed in 74.0% of early stage patients with HR+HER2- disease, compared to patients with HER2+ (77.8%) and TNBC (79.3%; p < 0.001). In adjusted analyses controlling for stage and clinical variables, women aged 80 years or older with HER2+ breast cancer and TNBC had a lower likelihood of BCS (ORHER2+ 0.72, 95% CI 0.65-0.80; ORTNBC 0.72, 95% CI 0.65-0.81), and an increased likelihood of adjuvant radiation (ORHER2+ 1.14, 95% CI 1.02-1.27; ORTNBC 1.40, 95% CI 1.25-1.57). Conclusions: One fifth of women with breast cancer over age 80 are diagnosed with HER2+ and triple-negative subtypes, which are associated with more aggressive local therapy. Further studies are warranted to determine if higher rates of adjuvant radiation optimize local control in older HER2+ and TNBC patients at increased risk for early locoregional recurrences.

Locoregional recurrence following pathologic complete response in patients with T1-3 N0 breast cancer treated with neoadjuvant chemotherapy, breast conserving surgery and whole breast radiation: Is a trial of omission of radiation warranted?

e12625

Background: Pathologic complete response(pCR) after neoadjuvant chemotherapy(NAC) in patients with breast cancer(BC) is associated with decreased recurrence and improved survival. In NSABP B18 and B27, 10-yr locoregional recurrence(LRR) after pCR in patients with Stage I-III BC undergoing breast conserving surgery(BCS) and whole breast RT(WBRT) was 5.2-6.9%. However, LRR may be overestimated as Her2 therapy was not used and only some eligible patients received endocrine therapy. A retrospective study using modern protocols found a 5-yr LRR of up to 2.6%. We hypothesize that LRR in N0 patients is even lower, and de-escalation of therapy should be examined. The study objective is to assess if a prospective trial of omission of WBRT after BCS in patients with N0 BC and pCR after NAC is warranted and to assess feasibility. Methods: Patients with T1-T3 N0 invasive BC diagnosed between Dec 2011-2017 treated with NAC and BCS were identified from a hospital BC registry. Health records were retrospectively reviewed to identify patients with pCR, defined as absence of residual invasive or in-situ disease(ypT0N0). Incidents of locoregional and distant recurrence were recorded. Results: Of 89 patients with T1-3 N0 invasive BC treated with NAC and BCS, 29(32.6%) had pCR. Median follow-up was 61.1 months. Median age was 55 yrs and median tumour size was 2.4cm. Receptor status was 16(55.2%) HR-Her2-, 4(13.8%) HR-Her2+, 7(24.1%) HR+Her2+ and 2(6.9%) HR+Her2-. NAC protocols consisted of an anthracycline and/or a taxane in 27(90%) patients, and 6 patients were treated on NAC trials. All patients with Her2+ disease received Her2 targeted therapy. Adjuvant endocrine therapy was taken by 8 of 9 patients with HR+ disease. All patients received WBRT without nodal RT. RT plan was available for 26(86.7%) patients. RT dose ranged from 40-50Gy, and all but 4 received tumour bed boost. There were no local or regional recurrence events at last follow-up. One patient developed brain metastases at 15.7 months. Conclusions: Over 6 years, 29 patients were identified that would be eligible for a prospective trial evaluating omission of WBRT after pCR in N0 patients treated with NAC and BCS. At median 5-yr follow-up, there were no locoregional recurrences in our cohort, demonstrating that the absolute benefit provided by WBRT is likely small. Our results indicate a prospective trial is warranted and will require multi-institution participation to accrue.

External beam accelerated partial breast irradiation versus whole breast irradiation after breast conserving surgery in women with ductal carcinoma in situ and node-negative breast cancer (RAPID): a randomised controlled trial

BACKGROUND

Whole breast irradiation delivered once per day over 3-5 weeks after breast conserving surgery reduces local recurrence with good cosmetic results. Accelerated partial breast irradiation (APBI) delivered over 1 week to the tumour bed was developed to provide a more convenient treatment. In this trial, we investigated if external beam APBI was non-inferior to whole breast irradiation.

METHODS

We did this multicentre, randomised, non-inferiority trial in 33 cancer centres in Canada, Australia and New Zealand. Women aged 40 years or older with ductal carcinoma in situ or node-negative breast cancer treated by breast conserving surgery were randomly assigned (1:1) to receive either external beam APBI (38·5 Gy in ten fractions delivered twice per day over 5-8 days) or whole breast irradiation (42·5 Gy in 16 fractions once per day over 21 days, or 50 Gy in 25 fractions once per day over 35 days). Patients and clinicans were not masked to treatment assignment. The primary outcome was ipsilateral breast tumour recurrence (IBTR), analysed by intention to treat. The trial was designed on the basis of an expected 5 year IBTR rate of 1·5% in the whole breast irradiation group with 85% power to exclude a 1·5% increase in the APBI group; non-inferiority was shown if the upper limit of the two-sided 90% CI for the IBTR hazard ratio (HR) was less than 2·02. This trial is registered with ClinicalTrials.gov, NCT00282035.

FINDINGS

Between Feb 7, 2006, and July 15, 2011, we enrolled 2135 women. 1070 were randomly assigned to receive APBI and 1065 were assigned to receive whole breast irradiation. Six patients in the APBI group withdrew before treatment, four more did not receive radiotherapy, and 16 patients received whole breast irradiation. In the whole breast irradiation group, 16 patients withdrew, and two more did not receive radiotherapy. In the APBI group, a further 14 patients were lost to follow-up and nine patients withdrew during the follow-up period. In the whole breast irradiation group, 20 patients were lost to follow-up and 35 withdrew during follow-up. Median follow-up was 8·6 years (IQR 7·3-9·9). The 8-year cumulative rates of IBTR were 3·0% (95% CI 1·9-4·0) in the APBI group and 2·8% (1·8-3·9) in the whole breast irradiation group. The HR for APBI versus whole breast radiation was 1·27 (90% CI 0·84-1·91). Acute radiation toxicity (grade ≥2, within 3 months of radiotherapy start) occurred less frequently in patients treated with APBI (300 [28%] of 1070 patients) than whole breast irradiation (484 [45%] of 1065 patients, p<0·0001). Late radiation toxicity (grade ≥2, later than 3 months) was more common in patients treated with APBI (346 [32%] of 1070 patients) than whole breast irradiation (142 [13%] of 1065 patients; p<0·0001). Adverse cosmesis (defined as fair or poor) was more common in patients treated with APBI than in those treated by whole breast irradiation at 3 years (absolute difference, 11·3%, 95% CI 7·5-15·0), 5 years (16·5%, 12·5-20·4), and 7 years (17·7%, 12·9-22·3).

INTERPRETATION

External beam APBI was non-inferior to whole breast irradiation in preventing IBTR. Although less acute toxicity was observed, the regimen used was associated with an increase in moderate late toxicity and adverse cosmesis, which might be related to the twice per day treatment. Other approaches, such as treatment once per day, might not adversely affect cosmesis and should be studied.

FUNDING

Canadian Institutes for Health Research and Canadian Breast Cancer Research Alliance.

Combining prostate cancer radiotherapy with therapies targeting the androgen receptor axis

Background

Prostate cancer (pca) is the most common non-dermatologic cancer and the 3rd leading cause of male cancer mortality in Canada. In patients with high-risk localized or recurrent pca, management typically includes the combination of long-term androgen deprivation therapy (adt) and radiotherapy (rt). New androgen-receptor-axis targeted therapies (arats), which await validation, offer an option to intensify therapy.

Methods

In this narrative review, we report the relevant history that has supported combining adt with rt. The literature in PubMed was searched for studies involving pca and novel arats (abiraterone acetate, enzalutamide, apalutamide, darolutamide) published between 1995 and 2019. Literature discussing clinical trials in which those modalities were combined was extracted and synthesized into a combined molecular and clinical discussion. Potential treatment intensification mechanisms and rationales are explored.

Results

Early results from three phase i/ii trials demonstrated that concurrent abiraterone acetate, adt, and rt is safe, improves the extent of chemical castration, and is associated with limited treatment failures. A single in vitro study implies synergy for radiosensitization beyond that facilitated by conventional adt. Studies investigating the combination of other arats with rt are under way, including multiple phase iii trials, but short-term results are not yet available.

Abstract 858: Enzalutamide versus abiraterone as a radiosensitizer in hormone-sensitive prostate cancer cells

Prostate cancer treatment is based on the estimated risk of recurrence in the U.S. Combined androgen deprivation therapy (ADT) with radiation therapy (XRT) is the standard of care for high-risk localized PCa. However, a large percentage of tumors are resistance to ADT due to continued AR signaling. Abiraterone (ABI), an androgen synthesis inhibitor, and Enzalutamide (ENZA), a potent AR antagonist, are new treatment options for metastatic castration resistance prostate cancer (mCRPC) patients. The aim of this study is to compare the efficacy of ENZA or ABI as a radiosensitizer in XRT therapy on PCa cells.

Methods: The effect of ENZA or ABI alone or in combination with XRT was assessed on hormone-sensitive (LNCaP, PC3-AR-T877A) and insensitive (PC3, PC3-AR V7) PCa cells using cell viability (MTT) and also clonogenic assays in different scheduling regimens: A- drug 24 h before XRT, B-drug 2h before XRT, or C- XRT followed by 24h later drug.

Results: We first determined the effect of ENZA or ABI on MTT assays in androgen-dependent (AD) and androgen-independent (AI) PCa cell lines. The results of MTT assay showed that ENZA inhibited the growth of the four different cell lines, LNCaP, PC3-T877A, PC3 and PC3 AR-V7 with IC50 values of 20, 22, 50, and 45μmol/L, respectively, after 24 hours of treatment. The same effect was observed on ABI treated cell lines. Radiosensitivity was not significantly increased in AD and AI PCa cell lines by ABI (DEF=1.00, in all cases) while there was a supra-additive dose enhancement factor (DEF= 1.75±0.08) for hormone-sensitive cells treated with ENZA (Table 1).

Conclusion: Our data indicates that ENZA acts as a much stronger radiosensitizer compared to ABI through different probable mechanisms of radiosensitivity.

Table 1. Dose Enhancement Factors calculations by scheduling ProtocolABCENZAABIENZAABIENZAABIADLNCaP1.35±0.021.05±0.011.75±0.081.001.30±0.051.00PC3-AR T877A1.30±0.031.001.65±0.011.001.35±0.061.05±0.02AIPC31.001.001.001.001.001.00PC3-AR V71.001.001.001.001.001.00

Citation Format: Maryam Ghashghaei, Thierry Muanza, Moulay Alaoui-Jamali, Miltiadis Paliouras, Mohammad Tamim Niazi. Enzalutamide versus abiraterone as a radiosensitizer in hormone-sensitive prostate cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 858.

A pilot study using dynamic contrast enhanced-MRI as a response biomarker of the radioprotective effect of memantine in patients receiving whole brain radiotherapy

PURPOSE

This pilot prospective study sought to determine whether dynamic contrast enhanced MRI (DCE-MRI) could be used as a clinical imaging biomarker of tissue toxicity from whole brain radiotherapy (WBRT).

METHOD

14 patients who received WBRT were imaged using dynamic contrast enhanced DCE-MRI prior to and at 8-weeks, 16-weeks and 24-weeks after the initiation of WBRT. Twelve of the patients were also enrolled in the RTOG 0614 trial, which randomized patients to the use of placebo or memantine. After the unblinding of the treatments received by RTOG 0614 patients, DCE-MRI measures of tumor tissue and normal appearing white matter (NAWM) vascular permeability (Initial Area Under the Curve (AUC) Blood Adjusted) was analyzed. Cognitive, quality-of-life (QOL) assessment and blood samples were collected according to the patient's ability to tolerate the exams. Circulating endothelial cells (CEC) were measured using flow cytometry.

RESULTS

Following WBRT, there was an increasing trend in the vascular permeability of tumors (p=0.09) and NAWM (p=0.06) with time. Memantine significantly (p=0.01) reduced NAWM AUC changes following radiotherapy. Patients on memantine retained (COWA p= 0.03) better cognitive functions than those on placebo. No association was observed between the level of CEC and DCE-MRI changes, time from radiotherapy or memantine use.

CONCLUSIONS

DCE-MRI can detect vascular damage secondary to WBRT. Our data suggests that memantine reduces WBRT-induced brain vasculature damages.

On Capturing Radiological Diagnoses of Brain Tumors to Provide Complete Population Data in Cancer Registries in Canada

Nonmalignant brain tumors are underreported by an estimated 60% in Canadian cancer registries. One explanation is that radiology facilities or their databases may not be adequately included in the cancer reporting infrastructure. A multidisciplinary stakeholder team met for 1 day, followed by teleconferences, to discuss the evidence for the importance of incorporating radiology diagnoses in brain tumor reports. A role for the neuroradiologist was delineated in brain tumor diagnosis and in ensuring that radiology report information is available to support cancer case ascertainment in the cancer surveillance system. It was noted that brain tumors identified through imaging are clinically managed depending on the diagnosis and prognosis of the disease, and that patient radiology reports become a part of a larger administrative information system. The proportion of nonmalignant brain tumors diagnosed using histology is lower in the United States (49.3%) than in Canada (59%), suggesting that a higher proportion of cases with nonhistologic (likely radiology) diagnosis are captured by the US system (eg, tumors of the sellar region, cranial and spinal tumors, and tumors of the meninges). Finding a way to use existing electronic radiology reports to identify nonmalignant brain tumors needs to be prioritized. This will require access to electronic radiology reports, as manual reporting is impractical. Once access is achieved, an electronic flag to identify new cases through a natural language processing algorithm could be pursued. As radiologists and cancer registrars become more familiar with each other's mandates and workflow demands, innovative and collaborative solutions to improve case ascertainment for brain and other cancers are likely to emerge.

Enhanced radiosensitization of enzalutamide via schedule dependent administration to androgen-sensitive prostate cancer cells

BACKGROUND

Prostate cancer (PCa) is a progressive disease and the most diagnosed cancer in men. The current standard of care for high-risk localized PCa is a combination of androgen deprivation therapy (ADT) and radiation (XRT). The majority of these patients however become resistant due to incomplete responses to ADT as a result of selective cells maintaining androgen receptor (AR) activity. Improvement can be made if increasing radiosensitivity is realized. Therefore, the aim of this study is to investigate the efficacy of the next-generation PCa drug Enzalutamide (ENZA), as a radiosensitizer in XRT therapy.

METHODS

Using a number of androgen-dependent (LNCaP, PC3-T877A) and androgen-independent (C4-2, 22RV1, PC3, PC3-AR V7) cell lines, the effect of ENZA as a radiosensitizer was studied alone or in combination with ADT and/or XRT. Cell viability and cell survival were assessed, along with determination of cell cycle arrest, DNA damage response and repair, apoptosis and senescence.

RESULTS

Our results indicated that either ENZA alone (in AR positive, androgen-dependent PCa cells) or in combination with ADT (in AR positive, hormone-insensitive PCa cells) potentiates radiation response [Dose enhancement factor (DEF) of 1.75 in LNCAP and 1.35 in C4-2] stronger than ADT + XRT conditions. Additionally, ENZA sensitized androgen dependent PCa cells to XRT in a schedule-dependent manner, where concurrent administration of ENZA and radiation lead to a maximal radiosensitization when compared to either drug administration prior or after XRT. In LNCaP cells, ENZA treatment significantly prolonged the presence of XRT-induced phospho-γH2AX up to 24 h after treatment; suggesting enhanced DNA damage. It also significantly increased XRT-induced apoptosis and senescence.

CONCLUSIONS

Our data indicates that ENZA acts as a much stronger radiosensitizer compared to ADT. We have also observed that its efficacy is schedule dependent and related to increased levels of DNA damage and a delay of DNA repair processes. Finally, the initial abrogation of DNA-PKcs activity by AR inhibition and its subsequent recovery might represent an important mechanism by which PCa cells acquire resistance to combined anti-androgen and XRT treatment. This work suggests a new use of ENZA in combination with XRT that could be applicable in clinical trial settings for patients with early and intermediate hormone responsive disease.

A Pilot Randomized Controlled Trial on the Effects of a Progressive Exercise Program on the Range of Motion and Upper Extremity Grip Strength in Young Adults With Breast Cancer

BACKGROUND

The diagnosis of breast cancer in young women (aged 18-45 years) has been increasing. Women are commonly left coping with treatment-related disabilities of the upper limb that can persist for > 2 years postoperatively.

PATIENTS AND METHODS

A total of 59 young breast cancer patients (29 in the intervention group and 30 in the control group) participated in a pilot prospective randomized controlled trial to determine whether a 12-week postradiation exercise program would improve long-term arm mobility, pain, and handgrip strength. During an 18-month period, range of motion, handgrip strength, and pain with shoulder movements were evaluated at 6 points.

RESULTS

Although the differences were not statistically significant, external rotation and horizontal abduction of the shoulder improved in the intervention group immediately after the exercise intervention (3 months) and showed a trend toward less pain on movement. However, at 18 months after radiation the control and intervention groups both retained a residual loss of range and persistent pain with movement. Radiation to the axilla and/or chest wall yielded long-term (18 months) limitations in flexion and horizontal abduction compared with hypofractionation, which resulted in greater flexion and external rotation at 18 months. The median grip strength of the study participants corresponded to the 10th percentile of healthy aged-matched white women.

CONCLUSION

The exercise intervention timed shortly after radiation improved short-term shoulder mobility and pain; however, these gains were not sustained at 18 months after radiation.

Radiation-Induced Oral Mucositis

Radiation-induced oral mucositis (RIOM) is a major dose-limiting toxicity in head and neck cancer patients. It is a normal tissue injury caused by radiation/radiotherapy (RT), which has marked adverse effects on patient quality of life and cancer therapy continuity. It is a challenge for radiation oncologists since it leads to cancer therapy interruption, poor local tumor control, and changes in dose fractionation. RIOM occurs in 100% of altered fractionation radiotherapy head and neck cancer patients. In the United Sates, its economic cost was estimated to reach 17,000.00 USD per patient with head and neck cancers. This review will discuss RIOM definition, epidemiology, impact and side effects, pathogenesis, scoring scales, diagnosis, differential diagnosis, prevention, and treatment.

Neurocognitive functions and psychological distress in young adults with cancer (YAC): A prospective, longitudinal study

10064

Background: Non-CNS cancer and treatments are associated with neurocognitive sequelae in older adults; whether YAC (age 18-39 yrs) are protected from these effects is unknown. In YAC, cancer interferes with education and occupational attainment and is associated with psychological distress. This prospective, inception-cohort study characterizes neurocognitive functions and psychological distress in YAC. Methods: YAC completed a 2-hr battery of standardized neurocognitive tests and questionnaires 1.7 ± 1 months after diagnosis prior to chemotherapy (mean ± SD, T1) and 8.2 ± 1.2 (T2) and 14.2 ± 1.6 (T3) months later. Healthy YA with no cancer history (HYA) were tested at similar time points. Tests were scored using published norms, transformed to T-scores, and grouped into neurocognitive domains. Results: YAC (n = 108; lymphoma, breast, gyne, GI, GU, sarcoma) were grouped according to whether they required chemotherapy (n = 70) or not (n = 38), and compared to 63 HYA. At baseline, there were no group differences in neurocognitive performance, number of impaired tests, or neurocognitive complaints (Kruskal Wallis, all p-values > .4). About 70% of each group completed assessments at T2 and T3. Mean performance improved over time (random effects models, all p-values < .01), but there were no group differences or interactions between group and time. There were also no differences in proportions of participants in each group whose test scores improved ( > 10 points) or declined ( < 10 points) from T1 to T2 or T3. Adjusting for psychological distress, fatigue, or neurocognitive complaints did not change these results, despite higher symptoms of somatic distress, anxiety and fatigue in YAC compared to healthy YA over time (all p-values < .03). Conclusions: Before chemotherapy and up to about 14 months later, YAC have elevated distress and fatigue, but do not demonstrate the cognitive decline reported in older cancer patients. Our findings are consistent with research suggesting that aging brains are more vulnerable to neurotoxic insult. Whether the effects of cancer treatment emerge later in YAC, placing them at risk for accelerated aging as reported in older patients, remains to be examined.

Time course of upper limb function and return-to-work post-radiotherapy in young adults with breast cancer: a pilot randomized control trial on effects of targeted exercise program

PURPOSE

Breast cancer (BC) diagnosis in young adults (YA) is rising, and both disease and treatments are aggressive in this population. Evidence supports the use of physical activity in reducing shoulder dysfunction, which is common among BC survivors. A pilot randomized clinical trial was performed to determine the effectiveness of a 12-week post-radiation exercise program in minimizing upper extremity dysfunction in YA with BC.

METHODS

Participants were randomized to either an exercise arm or a control arm receiving standard care. Data was collected over six time points using: the Disability of Arm, Shoulder, and Hand (DASH); the Metabolic Equivalent of Task-hours per week (MET-hours/week), and a post hoc questionnaire on return to work.

RESULTS

In total, 59 young women participated in the study (n = 29 exercise; n = 30 control). No statistically significant differences were found in overall DASH results between groups; however, those who underwent total mastectomy had residual upper limb dysfunction (p < 0.05). Both groups returned to pre-diagnosis activity levels by 18 months. Final evaluation showed that 86% of the women returned to work, and 89% resumed prior work activities with a decrease of 8.5 h/week.

CONCLUSION

Although the short-term targeted exercise program had no effect on long-term upper limb function post-radiation, timing and program specificity may require consideration of tissue healing post-radiation and surgery type. The majority of participants returned to work, however not returning to pre-diagnosis work hours.

IMPLICATIONS FOR CANCER SURVIVORS

Exercise interventions alone may not reverse the long-term sequelae of breast cancer treatment and allow young adult patients to return to work.

Effect of enzalutamide on sensitivity in prostate cancer cells to radiation by inhibition of DNA double strand break repair

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Background: Prostate cancer is the second leading cause of cancer-related deaths amongst men in North America. Data suggests that, following radiation therapy (XRT), androgen receptor (AR) enhances DNA damage repair and contributes to resistance of prostate cancer (PCa) cells to XRT. At present AR-pathway inhibition is the mainstay treatment of metastatic castration resistance prostate cancer (mCRPC). Enzalutamide (ENZA), a potent AR inhibitor is one of the approved drugs in this setting. The purpose of this study was to assess the potential radiosensitization of ENZA and its mechanism of action in hormone resistant PCa cells. Methods: The effect of ENZA alone or in combination with XRT was assessed on hormone-sensitive, (HS: LNCaP, PC3-T877A) and insensitive PCa cells (HI: PC3, PC3-AR V7, C4-2) using viability and clonogenic assays, cell cycle arrest and DNA damage analysis. Results: MTT assay demonstrates that ENZA significantly inhibits the proliferation of HS PCa cells in a dose dependent manner whereas CRPC required ENZA in combination with ADT (androgen deprivation therapy). Additionally, clonogenic assay proves that concurrent administration of ENZA or ADT+ENZA and XRT led to a supra-additive antitumor effect with the dose enhancement factor of 1.76±0.008 in LNCaP, 1.65±0.01 in PC3-T877A and 1.35±0.003 in C4-2 respectively at surviving fraction of 0.1. This effect was not observed in PC3 and PC3-AR V7 cells pre-treated with ENZA (in all cases DEF = 1 at SF = 0.1). Additionally, the level of γH2AX increased in HS cells and CRPC cells treated with ENZA/ADT+ENZA and XRT when compared to XRT alone. The enhanced H2AX activity remained unchanged up to 24 hours after combination treatment. Furthermore, there is an initial inhibition of DNA-PKcs in HS and CRPC cells treated with ENZA/ADT+ENZA administered before XRT. Conclusions: Our data suggest that the higher efficacy of ENZA/ENZA+ADT and XRT could be partially due to inhibition of DNA damage repair. Our results demonstrated a significant enhancement of XRT efficacy and confirms the rational for the ongoing combination clinical trials with XRT.

Pattern of Local Recurrence and Distant Metastasis in Breast Cancer By Molecular Subtype

BACKGROUND AND PURPOSE

 No longer considered a single disease entity, breast cancer is being classified into several distinct molecular subtypes based on gene expression profiling. These subtypes appear to carry prognostic implications and have the potential to be incorporated into treatment decisions. In this study, we evaluated patterns of local recurrence (LR), distant metastasis (DM), and association of survival with molecular subtype in breast cancer patients in the post-adjuvant radiotherapy setting.

MATERIAL AND METHODS

 The medical records of 1,088 consecutive, non-metastatic breast cancer patients treated at a single institution between 2004 and 2012 were reviewed. Estrogen/progesterone receptors (ER/PR) and human epidermal growth factor receptor-2 (HER2) enrichment were evaluated by immunohistochemistry. Patients were categorized into one of four subtypes: luminal-A (LA; ER/PR+, HER2-, Grade 1-2), luminal-B (LB; ER/PR+, HER2-, Grade > 2), HER2 over-expression (HER2; ER/PR-, HER2+), and triple negative (TN; ER/PR-, HER2-).  Results: The median follow-up time was 6.9 years. During the follow-up, 16% (174/1,088) of patients failed initial treatment and developed either LR (48) or DM (126). The prevalence of LR was the highest in TN (12%) and the lowest in LA (2%). Breast or chest wall relapse was the most frequent site (≈80%) of recurrence in LA, LB, and HER2 subtypes, whereas the regional lymph nodes and chest wall were the common sites of relapse in the TN group (50.0%). DM rates were 6.4% in LA, 12.1% in LB, 19.2% in HER2, and 27.4% in TN subgroups. Five-year survival rates were 84%, 83%, 84%, and 77% in the LA, LB, HER2 and TN subgroups, respectively. There was a statistically significant association between survival and molecular subtypes in an univariate analysis. In the adjusted multivariate analysis, the following variables were independent prognostic factors for survival: T stage, N stage, and molecular subtype.

CONCLUSIONS

 Of the four subtypes, the LA subtype tends to have the best prognosis, fairly high survival, and low recurrent or metastases rates. The TN and HER2 subtypes of breast cancer were associated with significantly poorer overall survival and prone to earlier recurrence and metastases. Our results demonstrate a significant association between molecular subtype and survival. The risk of death and relapse/metastases increases fewfold in TN compared to LA. Future prospective studies are warranted and could ultimately lead to the tailoring of adjuvant radiotherapy treatment fields based on both molecular subtype and the more conventional clinicopathologic characteristics.

Progression pattern and adverse events with bevacizumab in glioblastoma

BACKGROUND

The use of bevacizumab in the management of glioblastoma multiforme (gbm) remains controversial. In Canada, bevacizumab is approved for the treatment of recurrent gbm. We describe a pattern of progression across treatment lines in gbm.

METHODS

During 2008-2014, 64 patients diagnosed with gbm were treated with bevacizumab at McGill University hospitals. Of those patients, 30 (46.9%) received bevacizumab in the first line (B1L), and 34 (53.1%) received it in the second line and beyond (B2L+). The average length of treatment with bevacizumab was 24.4 weeks (range: 0-232.7 weeks). The patterns of progression were categorized as local, distant, diffuse, multifocal, or multi-pattern.

RESULTS

Local progression was seen in 46.7% of B1L patients and 26.5% of B2L+ patients, distant in 3.3% and 2.9%, diffuse in 20% and 47%, multifocal in 10% and 8.8%, and multi-pattern in 3.3% and 11.8%. No differences between the groups were observed for the distant (p = 0.3) or diffuse (p = 0.4) patterns. Grades 3 and 4 adverse events in the B1L and B2L+ groups were fatigue (33.3% vs. 17.6% respectively), hypertension (26.7% vs. 5.9%), thrombocytopenia (26.7% vs. 11.8%), neutropenia (26.7% vs. 11.8%), anemia (23.3% vs. 11.8%), leucopenia (20% vs. 8.8%), deep vein thrombosis (23.3% vs. 5.9%), seizure (16.7% vs. 8.8%), brain hemorrhage (6.7% vs. <1%), and delayed wound healing (6.7% vs. 2.9%). More total grades 3 and 4 adverse events occurred in the B1L group (p = 0.000519).

CONCLUSIONS

In our cohort, patterns of progression were not different in B1L and B2L+ patients. Moreover, both groups experienced similar adverse events, although more grades 3 and 4 events occurred in the B1L group, implying that severe adverse events in B1L patients could negatively affect survival outcomes.

Adipose mesenchymal stromal cells minimize and repair radiation-induced oral mucositis

BACKGROUND AIMS

Mesenchymal stromal cells (MSCs) have been used to minimize and repair radiation-induced normal tissue injury in the intestine, salivary gland, liver, skin, lungs and cardiac muscle. This study investigated the ability of adipose tissue-derived MSCs (aMSCs) to minimize and/or repair single dose radiation-induced oral mucositis (RIOM).

METHODS

Syngenic phenotypically and functionally characterized BALB/c mouse aMSCs were implanted intraperitoneally in a RIOM mouse model with different dosing protocols. Response was quantified macroscopically, microscopically and by using different histological and clinically relevant parameters.

RESULTS

Irradiation at 18 Gy generated a self-resolved single-dose RIOM BALB/c mouse model with 5.6 ± 0.3 days mean duration (95% confidence interval (CI) 4.233-7.1 days) and 100% survival rate. Intraperitoneal implantation of 5 doses of 2.5 million freshly cultured syngenic aMSCs significantly and reproducibly reduced RIOM ulcer duration to 1.6 ± 0.3 days (95% CI 0.0233-3.1 days, a 72% reduction in RIOM ulcer duration), ulcer size and ulcer floor epithelial height. The therapeutic benefits were significantly dependent on dose size and frequency, number of doses, and therapy onset time. aMSCs therapy significantly minimized the RIOM-related weight loss, accelerated the weight gain and improved irradiated animals' hydration and nutritional status. aMSCs therapy did not potentiate head and neck cancer in vitro.

CONCLUSIONS

Syngenic freshly cultured aMSCs significantly minimized and repaired radiation-induced oral mucositis with a 72% reduction in ulcer duration. aMSCs dose size and frequency, number of doses and therapy onset time are the main keys for optimized therapeutic outcome. aMSCs therapy did not stimulate Head and Neck cancer cell growth in-vitro.

Single-Dose Radiation-Induced Oral Mucositis Mouse Model

The generation of a self-resolved radiation-induced oral mucositis (RIOM) mouse model using the highest possibly tolerable single ionizing radiation (RT) dose was needed in order to study RIOM management solutions. We used 10-week-old male BALB/c mice with average weight of 23 g for model production. Mice were treated with an orthovoltage X-ray irradiator to induce the RIOM ulceration at the intermolar eminence of the animal tongue. General anesthesia was injected intraperitoneally for proper animal immobilization during the procedure. Ten days after irradiation, a single RT dose of 10, 15, 18, 20, and 25 Gy generated a RIOM ulcer at the intermolar eminence (posterior upper tongue surface) with mean ulcer floor (posterior epithelium) heights of 190, 150, 25, 10, and 10 μm, respectively, compared to 200 μm in non-irradiated animals. The mean RIOM ulcer size % of the total epithelialized upper surface of the animal tongue was RT dose dependent. At day 10, the ulcer size % was 2, 5, 27, and 31% for 15, 18, 20, and 25 Gy RT, respectively. The mean relative surface area of the total epithelialized upper surface of the tongue was RT dose dependent, since it was significantly decreased to 97, 95, 88, and 38% with 15, 18, 20, and 25 Gy doses, respectively, at day 10 after RT. Subcutaneous injection of 1 mL of 0.9% saline/6 h for 24 h yielded a 100% survival only with 18 Gy self-resolved RIOM, which had 5.6 ± 0.3 days ulcer duration. In conclusion, we have generated a 100% survival self-resolved single-dose RIOM male mouse model with long enough duration for application in RIOM management research. Oral mucositis ulceration was radiation dose dependent. Sufficient hydration of animals after radiation exposure significantly improved their survival.

Neurocognitive function and psychological distress in young adults (YA) with cancer

199

Background: Cancer treatment is associated with neurocognitive sequelae and changes in structural and functional brain imaging in older adults, even if they do not receive central nervous system directed therapy. Because the brain continues to develop into the 3rd decade of life, YA (age 18-39 yrs) may also be vulnerable to neurocognitive dysfunction. In YA, cancer disrupts acquisition of developmental milestones and is associated with psychological distress. This study aims to characterize neurocognitive functions and its relation to psychological distress in YA. Here we present baseline results of our longitudinal study. Methods: In this prospective, inception-cohort study, we recruited 3 groups of YA from ambulatory oncology clinics: YA with cancers (YAC; lymphoma, breast, gynecology, gastrointestinal, genitourinary, sarcoma) who required chemotherapy (YAC+, n = 55), YAC who do not require it (YAC-, n = 31), and healthy YA (HYA, n = 54). Participants completed a 2-hr battery of standardized neurocognitive tests and validated self-report questionnaires. YAC were assessed within 3 months of diagnosis, and YAC+prior to chemotherapy. Test scores were converted to age-corrected scaled scores and transformed to z-scores (mean 0, SD 1). A global neurocognitive function score and 6 domain scores were evaluated. Results: There were no group differences in neurocognitive domains (ANOVA, all p-values > .1), or in the number of impaired test scores (defined as z < -1). YAC+ reported greater symptoms of somatic distress (p = .001) and anxiety (p = .004) than both HYA and YAC-. Symptoms were unrelated to neurocognitive performance (ρ < .16 for all). However, each group had poorer memory compared to population norms (1-sample t-tests: YAC+ p = .007; YAC- p = .047; HYA p = .023). Conclusions: Prior to treatment, neurocognitive functions of YAC were not different from HYA, suggesting that cancer itself is not a neurocognitive risk factor in YA. It is important to use appropriate control groups, rather than relying on normative data for comparison. We continue to follow this cohort to document neurocognitive function and distress over time, and to identify risk factors that contribute to outcomes in YA.

Adipose mesenchymal stromal cells response to ionizing radiation

BACKGROUND AIMS

This study evaluates the biological response of adipose tissue-derived mesenchymal stromal cells (aMSCs) to ionizing radiation (IR).

METHODS

Irradiated BALB/c mice aMSCs were characterized for functionality and phenotype. The clonogenic capacity of irradiated aMSCs was assessed and compared with those of metastatic breast cancer cell line (4T1) and normal mouse fibroblasts (NIH3T3-wt). We investigated the IR-induced DNA damage response, apoptosis, changes in cell cycle (CC) dynamics and protein and gene expression.

RESULTS

Irradiated and non-irradiated aMSCs were able to differentiate into adipocytes, chondrocytes and osteocytes with no significant difference. Irradiated aMSCs maintained the expression of mesenchymal stromal cells (MSCs) surface antigens and, as expected, were negative for hematopoietic stem cells (HSCs) surface antigens when tested up to 7 days after IR for all irradiation doses with no significant difference. Clonogenically, irradiated aMSCs had higher relative survival fraction and plating efficiency than 4T1 and NIH3T3-wt. Irradiated aMSCs expressed higher □H2AX and significantly showed faster and more time-efficient IR-induced DNA damage response evident by up-regulated DNA-PKcs and RAD51. Two hours after IR, most of aMSCs DNA damage/repair-related genes showed up-regulation that disappeared within 6 h after IR. Irradiated aMSCs showed a significant rise and an earlier peak of p-ATM-dependent and -independent (p84/5E10-mediated) G2/M CC arrest compared with 4T1 and NIH3T3-wt.

CONCLUSIONS

After IR exposure, aMSCs showed a robust and time-efficient radiation-induced DNA damage repair response, stable phenotypical characteristics and multi-lineage differentiation potential, suggesting they may be reliable candidates for cell therapy in radiation oncology regenerative medicine.

Giant petroclival primary intradural chordoma: case report and systematic review of the literature

Background Chordomas are rare, locally aggressive neoplasms thought to arise from notochordal remnants in the axial skeleton. Primary intradural chordomas are considered to be extremely rare. In this article a giant intradural petroclival chordoma is presented, and a synthesis of the available literature is performed to measure overall survival (OS) and recurrence-free survival (RFS) and to identify prognostic factors.

Methods A systematic Medline review yielded 47 patients with purely intradural tumors from 38 publications including 39 chordomas, 8 cases of ecchordosis physaliphora, and 1 case with features of both. The 5-year OS and RFS were calculated based on the Kaplan-Meier method. Risk factors for progression or mortality were analyzed using binomial logistic regression.

Results Maximal tumor diameter varied from 1.5 to 6.0 cm (mean: 3.2 cm). Tumors were located predominantly in the prepontine area (66.7%). Combined 5-year Kaplan-Meier OS and RFS were 77% ± 11% and 74% ± 11%, respectively. Incomplete surgical resection, larger tumor diameter, and an elevated Ki-67 index were statistically more frequent in cases of recurrence and mortality.

Conclusions Based on a systematic literature review, the behavior of primary intradural chordomas may be closer to typical chordomas than was previously thought.

Effects of dna-dependent protein kinase inhibition by NU7026 on dna repair and cell survival in irradiated gastric cancer cell line N87

Repair of radiation-induced dna double-strand breaks is a key mechanism in cancer cell radio-resistance. The synthesized compound NU7026 specifically inhibits dna-dependent protein kinase (dna-pk) within the non-homologous end-joining repair mechanism. Earlier studies demonstrated increased radiosensitivity in dna-pk deficient cells compared with wild-type cells. In chronic leukemia cells, NU7026 appears to enhance the cytotoxic effect of chlorambucil. The radio-modifying effects of NU7026 on cell survival, cell cycle, apoptosis, and dna double-strand break repair have yet to be studied in gastric cancer cells.

METHODS

The gastric cancer cell line N87 was treated with 0 Gy or 4 Gy in the presence of NU7026 at a dose range of 0-20 μmol/L. Clonogenic assays were used to assess cell survival after treatment. Cell-cycle distribution was analyzed using propidium iodide with fluorescence-activated cell sorting. Apoptosis was detected using annexin-V and propidium iodide with fluorescence-activated cell sorting. The γH2AX assay was used to measure dna double-strand breaks.

RESULTS

Statistically significant increases in G2/M arrest were observed in N87 cells treated with radiation and NU7026 compared with those treated with radiation alone (p = 0.0004). Combined treatment also led to an increase in apoptosis (p = 0.01). At 24 hours, the γH2AX analysis revealed more dna double-strand breaks in N87 cells treated with radiation and NU7026 than in those treated with radiation alone (p = 0.04). Clonogenic assays demonstrated declining cell survival as both the radiation and the NU7026 dose increased. The dose enhancement factor at 0.1 survival fraction was 1.28 when N87 cells were treated with 4 Gy radiation and 5 μmol/L NU7026.

CONCLUSIONS

In gastric cancer cells, NU7026 appears to enhance the cytotoxic effect of irradiation as assessed by clonogenic assays. This increased cytotoxicity might be the result of an increase in dna double-strand breaks resulting in G2/M cell arrest and possibly higher levels of apoptosis.

Effect of exercise in reducing breast and chest-wall pain in patients with breast cancer: a pilot study

BACKGROUND

Breast or chest-wall pain (BCP) is prevalent in 20%-50% of breast cancer survivors, and it affects quality of life (QOL). To determine the feasibility and potential efficacy of an exercise program to improve patient QOL and BCP, such a program was offered to breast cancer patients suffering from BCP.

METHODS

The study enrolled 10 breast cancer patients with moderate-to-severe BCP at 3-6 months after completion of all adjuvant treatments. These patients participated in a 12-week comprehensive health improvement program (CHIP). Intensity was adjusted to reach 65%-85% of the patient's maximal heart rate. Before the CHIP and at 1 and 6 months after completion of the CHIP, QOL and pain were measured using questionnaires [European Organisation for Research and Treatment of Cancer Quality of Life core and breast cancer modules (QLQ-C30, -BR23) and the McGill Pain Questionnaire short form] completed by the patients. Results were compared with those from case-matched control subjects from another study at McGill University.

RESULTS

After the CHIP, patients reported significant and clinically important improvements in QOL and symptoms. At 1 and 6 months post-CHIP, patients in the study felt, on average, better in overall QOL than did historical control subjects.

CONCLUSIONS

Our study suggests that patients who experience chronic bcp may benefit from an exercise program. A randomized controlled trial is warranted.

Abstract 2506: Preclinical evaluation of sorafenib in combination with ionizing radiation in metastatic breast cancer model

Sorafenib tosylate (Bay 54-9085) is an oral, small molecule multikinase inhibitor of several targets including RAF/MEK/ERK signaling, vascular endothelial growth factor receptor-2 (VEGFR-2), VEGFR-3, and platelet derived growth factor receptor-beta (PDGFR-b). Sorafenib has shown clinical efficacy in solid tumors such as renal cell and hepatocellular carcinomas. Retrospective analysis of breast cancer patients has shown an unfavorable prognosis in patients with high expression level of VEGF, indicating that VEGF could be associated with efficacy of chemotherapy and radiotherapy. It has also been shown that radiation resistance is partially due to tumor cell production of angiogenic cytokines, particularly VEGF that protects endothelial cells through survival pathways. The aim of this study is to investigate if radiation response is enhanced through inhibition of p-VEGFR2/PDGFR-b by Sorafenib and if the combination of Sorafenib and radiation will increase the treatment response in a metastatic breast cancer model.

Mouse metastatic mammary cancer cells, 4T1 were used in this study. Clonogenic assay was performed to assess the radiomodulating effect of Sorafenib. In addition, cell cycle analysis and annexin-V binding assay were performed 24 and 48 hrs post treatment respectively. To confirm our in vitro data, a tumor growth delay assay was completed in a syngeneic mouse model.

Western blot analysis showed strong dose dependent inhibition of ERK1/2 phosphorylation by sorafenib. Our clonogenic assay showed a supra-additive effect of Sorafenib (7.5 μM) and radiation (4 Gy) with a dose enhancement factor (DEF) of 1.81. Sorafenib in combination with radiation demonstrated a significant G2/M cell cycle arrest (p&lt;0.0001). Moreover, annexin-V staining assay showed a significant increase in the level of apoptosis in cells treated with both sorafenib and radiation (p&lt;0.0004). Our in vivo results strongly suggest that radiation prolongs the anti tumor activity of sorafenib. In addition, tumor growth was delayed when radiation was combined with sorafenib concurrently (tumor growth delay was increased from 10.5 days in irradiated group to 18 days in combined treatment group).

Our results demonstrate that sorafenib increases both the level of apoptosis and the sensitivity of 4T1 cancer cells to radiation. The higher potency of sorafenib combined with radiation can be partially due to the strong cell cycle arrest at G2/M phase. Moreover, our in vivo results show that sorafenib in combination with radiation exhibit a superior tumor growth control. Overall, our findings suggest that greater treatment response may be achieved when sorafenib is combined with radiation. More studies are being conducted to investigate the optimal schedule for this combination.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2506. doi:10.1158/1538-7445.AM2011-2506

Hypofractionated radiotherapy and adjuvant chemotherapy do not increase radiation-induced dermatitis in breast cancer patients

PURPOSE

Radiation-induced dermatitis is a common side effect of breast irradiation, with hypofractionation being a well-known risk factor. In the context of the widespread adoption of hypofractionated breast radiotherapy, we evaluated the effect of hypofractionated radiotherapy on the incidence of skin toxicity in patients receiving adjuvant chemotherapy.

PATIENTS AND METHODS

We retrospectively reviewed the records of patients with breast cancer treated from 2004 to 2006 at a single institution. Patients undergoing lumpectomy with or without adjuvant chemotherapy followed by hypofractionated radiotherapy consisting of 42.4 Gy in 16 fractions were included in the study. Using cosmetic and skin toxicity scales, all patients were evaluated weekly during treatment and at scheduled follow-up visits with the radiation oncologist.

RESULTS

During the study period, 162 patients underwent radiotherapy, and 30% of those (n = 48) received chemotherapy. Radiotherapy boost to the tumour bed was more common in the chemotherapy group [n = 20 (42%)] than in the radiotherapy-alone group [n = 30 (26%)]. We observed no statistically significant difference between the groups with regard to acute skin toxicity of grade 3 or higher (2.1% in the chemotherapy group vs. 4.4% in the radiation-alone group, p = 0.67) or of grades 1-2 toxicity (62.5% vs. 51.7% respectively, p = 0.23). There was also no significant difference in late grade 3 or higher skin toxicity between the groups (2.1% vs. 0% respectively, p = 0.30) or in grades 1-2 toxicity (20.8% vs. 25.5% respectively, p = 0.69). Similarly, excellent or good cosmetic result scores were similar in both groups (p = 0.80)

CONCLUSIONS

In our single-institution review, we observed no adverse effects of chemotherapy in combination with hypofractionated whole-breast irradiation. Further investigations are necessary to better elucidate the effects of chemotherapy on skin toxicity in the context of hypofractionated irradiation.

Brg-1 mediates the constitutive and fenretinide-induced expression of SPARC in mammary carcinoma cells via its interaction with transcription factor Sp1

Background

Secreted protein, acidic and rich in cysteine (SPARC) is a matricellular protein that mediates cell-matrix interactions. It has been shown, depending on the type of cancer, to possess either pro- or anti-tumorigenic properties. The transcriptional regulation of the SPARC gene expression has not been fully elucidated and the effects of anti-cancer drugs on this process have not been explored.

Results

In the present study, we demonstrated that chromatin remodeling factor Brg-1 is recruited to the proximal SPARC promoter region (-130/-56) through an interaction with transcription factor Sp1. We identified Brg-1 as a critical regulator for the constitutive expression levels of SPARC mRNA and protein in mammary carcinoma cell lines and for SPARC secretion into culture media. Furthermore, we found that Brg-1 cooperates with Sp1 to enhance SPARC promoter activity. Interestingly, fenretinide [N-4(hydroxyphenyl) retinamide, 4-HPR], a synthetic retinoid with anti-cancer properties, was found to up-regulate the transcription, expression and secretion of SPARC via induction of the Brg-1 in a dose-dependent manner. Finally, our results demonstrated that fenretinide-induced expression of SPARC contributes significantly to a decreased invasion of mammary carcinoma cells.

Conclusions

Overall, our results reveal a novel cooperative role of Brg-1 and Sp1 in mediating the constitutive and fenretinide-induced expression of SPARC, and provide new insights for the understanding of the anti-cancer effects of fenretinide.