Interplay of Immunosuppression and Immunotherapy Among Patients With Cancer and COVID-19

Importance

Cytokine storm due to COVID-19 can cause high morbidity and mortality and may be more common in patients with cancer treated with immunotherapy (IO) due to immune system activation.

Objective

To determine the association of baseline immunosuppression and/or IO-based therapies with COVID-19 severity and cytokine storm in patients with cancer.

Design, Setting, and Participants

This registry-based retrospective cohort study included 12 046 patients reported to the COVID-19 and Cancer Consortium (CCC19) registry from March 2020 to May 2022. The CCC19 registry is a centralized international multi-institutional registry of patients with COVID-19 with a current or past diagnosis of cancer. Records analyzed included patients with active or previous cancer who had a laboratory-confirmed infection with SARS-CoV-2 by polymerase chain reaction and/or serologic findings.

Exposures

Immunosuppression due to therapy; systemic anticancer therapy (IO or non-IO).

Main Outcomes and Measures

The primary outcome was a 5-level ordinal scale of COVID-19 severity: no complications; hospitalized without requiring oxygen; hospitalized and required oxygen; intensive care unit admission and/or mechanical ventilation; death. The secondary outcome was the occurrence of cytokine storm.

Results

The median age of the entire cohort was 65 years (interquartile range [IQR], 54-74) years and 6359 patients were female (52.8%) and 6598 (54.8%) were non-Hispanic White. A total of 599 (5.0%) patients received IO, whereas 4327 (35.9%) received non-IO systemic anticancer therapies, and 7120 (59.1%) did not receive any antineoplastic regimen within 3 months prior to COVID-19 diagnosis. Although no difference in COVID-19 severity and cytokine storm was found in the IO group compared with the untreated group in the total cohort (adjusted odds ratio [aOR], 0.80; 95% CI, 0.56-1.13, and aOR, 0.89; 95% CI, 0.41-1.93, respectively), patients with baseline immunosuppression treated with IO (vs untreated) had worse COVID-19 severity and cytokine storm (aOR, 3.33; 95% CI, 1.38-8.01, and aOR, 4.41; 95% CI, 1.71-11.38, respectively). Patients with immunosuppression receiving non-IO therapies (vs untreated) also had worse COVID-19 severity (aOR, 1.79; 95% CI, 1.36-2.35) and cytokine storm (aOR, 2.32; 95% CI, 1.42-3.79).

Conclusions and Relevance

This cohort study found that in patients with cancer and COVID-19, administration of systemic anticancer therapies, especially IO, in the context of baseline immunosuppression was associated with severe clinical outcomes and the development of cytokine storm.

Trial Registration

ClinicalTrials.gov Identifier: NCT04354701.

Association of clinical factors and recent anticancer therapy with COVID-19 severity among patients with cancer: a report from the COVID-19 and Cancer Consortium

BACKGROUND

Patients with cancer may be at high risk of adverse outcomes from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We analyzed a cohort of patients with cancer and coronavirus 2019 (COVID-19) reported to the COVID-19 and Cancer Consortium (CCC19) to identify prognostic clinical factors, including laboratory measurements and anticancer therapies.

PATIENTS AND METHODS

Patients with active or historical cancer and a laboratory-confirmed SARS-CoV-2 diagnosis recorded between 17 March and 18 November 2020 were included. The primary outcome was COVID-19 severity measured on an ordinal scale (uncomplicated, hospitalized, admitted to intensive care unit, mechanically ventilated, died within 30 days). Multivariable regression models included demographics, cancer status, anticancer therapy and timing, COVID-19-directed therapies, and laboratory measurements (among hospitalized patients).

RESULTS

A total of 4966 patients were included (median age 66 years, 51% female, 50% non-Hispanic white); 2872 (58%) were hospitalized and 695 (14%) died; 61% had cancer that was present, diagnosed, or treated within the year prior to COVID-19 diagnosis. Older age, male sex, obesity, cardiovascular and pulmonary comorbidities, renal disease, diabetes mellitus, non-Hispanic black race, Hispanic ethnicity, worse Eastern Cooperative Oncology Group performance status, recent cytotoxic chemotherapy, and hematologic malignancy were associated with higher COVID-19 severity. Among hospitalized patients, low or high absolute lymphocyte count; high absolute neutrophil count; low platelet count; abnormal creatinine; troponin; lactate dehydrogenase; and C-reactive protein were associated with higher COVID-19 severity. Patients diagnosed early in the COVID-19 pandemic (January-April 2020) had worse outcomes than those diagnosed later. Specific anticancer therapies (e.g. R-CHOP, platinum combined with etoposide, and DNA methyltransferase inhibitors) were associated with high 30-day all-cause mortality.

CONCLUSIONS

Clinical factors (e.g. older age, hematological malignancy, recent chemotherapy) and laboratory measurements were associated with poor outcomes among patients with cancer and COVID-19. Although further studies are needed, caution may be required in utilizing particular anticancer therapies.

CLINICAL TRIAL IDENTIFIER

NCT04354701.

Clinical impact of COVID-19 on patients with cancer (CCC19): a cohort study

BACKGROUND

Data on patients with COVID-19 who have cancer are lacking. Here we characterise the outcomes of a cohort of patients with cancer and COVID-19 and identify potential prognostic factors for mortality and severe illness.

METHODS

In this cohort study, we collected de-identified data on patients with active or previous malignancy, aged 18 years and older, with confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection from the USA, Canada, and Spain from the COVID-19 and Cancer Consortium (CCC19) database for whom baseline data were added between March 17 and April 16, 2020. We collected data on baseline clinical conditions, medications, cancer diagnosis and treatment, and COVID-19 disease course. The primary endpoint was all-cause mortality within 30 days of diagnosis of COVID-19. We assessed the association between the outcome and potential prognostic variables using logistic regression analyses, partially adjusted for age, sex, smoking status, and obesity. This study is registered with ClinicalTrials.gov, NCT04354701, and is ongoing.

FINDINGS

Of 1035 records entered into the CCC19 database during the study period, 928 patients met inclusion criteria for our analysis. Median age was 66 years (IQR 57-76), 279 (30%) were aged 75 years or older, and 468 (50%) patients were male. The most prevalent malignancies were breast (191 [21%]) and prostate (152 [16%]). 366 (39%) patients were on active anticancer treatment, and 396 (43%) had active (measurable) cancer. At analysis (May 7, 2020), 121 (13%) patients had died. In logistic regression analysis, independent factors associated with increased 30-day mortality, after partial adjustment, were: increased age (per 10 years; partially adjusted odds ratio 1·84, 95% CI 1·53-2·21), male sex (1·63, 1·07-2·48), smoking status (former smoker vs never smoked: 1·60, 1·03-2·47), number of comorbidities (two vs none: 4·50, 1·33-15·28), Eastern Cooperative Oncology Group performance status of 2 or higher (status of 2 vs 0 or 1: 3·89, 2·11-7·18), active cancer (progressing vs remission: 5·20, 2·77-9·77), and receipt of azithromycin plus hydroxychloroquine (vs treatment with neither: 2·93, 1·79-4·79; confounding by indication cannot be excluded). Compared with residence in the US-Northeast, residence in Canada (0·24, 0·07-0·84) or the US-Midwest (0·50, 0·28-0·90) were associated with decreased 30-day all-cause mortality. Race and ethnicity, obesity status, cancer type, type of anticancer therapy, and recent surgery were not associated with mortality.

INTERPRETATION

Among patients with cancer and COVID-19, 30-day all-cause mortality was high and associated with general risk factors and risk factors unique to patients with cancer. Longer follow-up is needed to better understand the effect of COVID-19 on outcomes in patients with cancer, including the ability to continue specific cancer treatments.

FUNDING

American Cancer Society, National Institutes of Health, and Hope Foundation for Cancer Research.

Iatrogenic constipation from barium blockade: A case report

Barolith, a mixture of inspissated barium and feces, is a rare complication of barium-contrast studies that lead to intestinal obstruction. With the high morbidity associated with barolith impaction, we recommend that physicians be more aware of complications, increase prompt diagnosis, and initiation of laxatives once discovered.

Radiation Therapy for Positive Surgical Margins in Women ≥70 Years with Stage I, Estrogen Receptor-positive Breast Cancer

BACKGROUND/AIM

A re-excision for positive margin(s) following a lumpectomy for invasive breast cancer is a standard recommendation. However, for elderly women with stage I estrogen receptor-positive (ER+) tumors, who may be at higher surgical risk, whether radiation therapy without re-excision will be adequate is not known.

PATIENTS AND METHODS

We evaluated a cohort of 53,950 women aged ≥70 years with Stage I, ER+ breast cancer who had lumpectomy and anti-hormone therapy diagnosed between 2004 and 2011 in the National Cancer Data Base. Patients were divided into four groups: 1) negative margins without radiation (XRT), 2) negative margins with XRT, 3) positive margins without XRT, and 4) positive margins with XRT. Clinicopathological and sociodemographic variables were compared among these groups. Univariable and multivariable analysis were employed.

RESULTS

The 5-year overall survival (OS) rates for the groups were as follows: 1) negative margins without radiation (XRT); 77.1%, 2) negative margins with XRT; 90.0%, 3) positive margins without XRT; 62.9%, and 4) positive margins with XRT; 86.8% (p<0.0001). Significant predictors (p<0.01) of OS include treatment groups, age, income status, facility type, facility location, tumor size, tumor grade, and comorbidities.

CONCLUSION

Radiation therapy for positive surgical margins without re-excision may be a viable option for elderly women with stage I, ER+ tumor treated with lumpectomy and hormonal therapy.

Abstract 675: Analysis of post mastectomy radiation outcomes in breast cancer patients with 1-3 positive axillary lymph nodes : A review of the National Cancer Database

Background: The benefit of Post mastectomy radiation (PMRT) has been confirmed in breast cancer patients with ≥4 positive axillary lymph nodes (PALN). The role of PMRT in patients with 1-3 PALN is not well defined.

Methods: We identified 102,103 breast cancer patients with mastectomy and 1-3 PALN registered to the National Cancer Database (NCDB) between 2004- 2012. Primary outcome was overall survival. Adjusted variables include age, race, comorbidity, insurance, income, education, distance travelled, diagnosing/treating facility, treatment delays, hormone receptor status, regional lymph nodes, stage and treatment modalities. 8 treatment modalities were defined: +/- radiation, +/- adjuvant chemotherapy, +/- adjuvant hormone therapy. Univariate and multivariate analyses were performed to identify factors that predict overall survival.

Results: Patients with 1, 2, and 3 PALN comprised 55.7%, 27.6% and 16.6% of the population, respectively. 58.4% of patients received radiation. Younger age (&lt;50years), Asian race, private insurance, annual income &gt;$46,000, lower AJCC tumor stage, hormone receptor positive status and lower number of PALN were independently associated with a lower risk of death in multivariate analysis. Compared to patients who did not receive additional therapy, radiation alone was associated with a non-significant increased risk of death HR 1.10 (95% CI [0.92-1.31]). The addition of hormone and chemotherapy significantly reduced the risk of death HR 0.36 (95% CI [0.33- 0.3]). Stratified by regional lymph nodes, patients with 1 or 2 PALN had a trend towards increased risk of death with radiation alone compared to patients who did not receive radiation, hormone or chemotherapy. In patients with 3 PALN, there was a trend towards reduced mortality with radiation alone HR 0.89 (95% CI [0.63- 1.23]).

Conclusions: To our knowledge this retrospective study is the largest such review of the outcomes of breast cancer patients with 1-3 PALN receiving adjuvant radiation following mastectomy. Our study found no measurable reduction in risk of death for those patients who received radiation therapy compared to those who did not. We also note that, with an increasing number of PALN, patients receiving PMRT either alone, or with chemotherapy or hormonal therapy, appeared to have a decrease in the risk of death compared to the populations that had not received PMRT. Based on this analysis, the routine addition of radiation following mastectomy is not indicated in patients with 1-3 PALN. The addition of adjuvant hormone and/or chemotherapy was associated with a significant survival advantage.

Citation Format: Anu Paul, Runhua Shi, Prakash Peddi, Gary Burton. Analysis of post mastectomy radiation outcomes in breast cancer patients with 1-3 positive axillary lymph nodes : A review of the National Cancer Database [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 675.

Influence of facility type on survival outcomes after pancreatectomy for pancreatic adenocarcinoma

INTRODUCTION

Although a volume-outcome relationship has been well established for pancreatectomy, little is known about differences in mortality by facility type. The objective of this study is to evaluate the impact of facility type on short-term and long-term survival outcomes for patients with pancreatic adenocarcinoma who underwent pancreatectomy and identify determinants of overall survival (OS).

METHODS

A cohort of 33,382 patients with Stage I-III pancreatic adenocarcinoma diagnosed between 1998 and 2011 were evaluated from the National Cancer Data Base. Clinicopathological, sociodemographic and treatment variables were compared among three facility types where patients received resection: (i) community cancer program (CCP), (ii) comprehensive community cancer program (CCCP), and (iii) academic research program (ARP). 5-year OS was calculated using the Kaplan-Meier method.

RESULTS

Despite ARP having significantly higher percentage of poorly differentiated tumors, higher T-stage tumors, more positive lymph nodes, and greater circle distance compared to the other facilities, it had the highest 5-yr OS. The 5-yr OS for CCP, CCCP, and ARP was 11.2%, 13.2%, and 16.6%, respectively (P < 0.0001) and the median survival time (months) was 12.4, 15.6 and 19.1, respectively.

CONCLUSION

Patients receiving pancreatic resection at an ARP yielded a higher 5-year OS compared to CCP or CCCP.

Spontaneous tumor lysis syndrome in colon cancer: a case report and literature review

Although tumor lysis syndrome is well described, it is rarely seen or suspected in solid malignancies. Early recognition of this entity is paramount in reducing morbidity and mortality. Treating physicians should be aware of this possibility in solid tumor patients with either bulky disease or extensive liver involvement.

Impact of CALGB 9343 Trial and Sociodemographic Variation on Patterns of Adjuvant Radiation Therapy Practice for Elderly Women (≥70 Years) with Stage I, Estrogen Receptor-positive Breast Cancer: Analysis of the National Cancer Data Base

BACKGROUND

The Cancer and Leukemia Group B (CALGB) 9343 trial demonstrated that adjuvant radiation therapy (RT) can be omitted in women 70 years or older, with small (≤2 cm), negative lymph nodes, estrogen receptor (ER)-positive breast cancer. We examined whether RT usage following the CALGB publication had decreased over time and evaluated sociodemographic and clinical factors associated with RT omission.

MATERIALS AND METHODS

From the National Cancer Data Base, we analyzed a cohort of 120,308 women aged 70 years or older with stage I, ER-positive breast cancer who underwent lumpectomy. Patients were classified into two groups based on the time of CALGB 9343 publication: (i) pre-CALGB (up to 2004), and (ii) post-CALGB (2005-2012). Clinicopathological and sociodemographic variables were compared between pre- and post-CALGB groups. Chi-square and multivariable logistic regression were employed, with the omission of adjuvant RT as the primary outcome in the regression analysis.

RESULTS

Radiation therapy usage decreased by 4.1% after CALGB publication (on average 71.6% pre-CALGB vs. 67.5% post-CALGB; p<0.0001). Almost one-third of women aged ≥85 years received RT in the post-CALGB group. In a multivariable model, the variables significantly associated with increased odds for omission of RT in the post-CALGB group were: advanced age, African-American, increased great circle distance, therapy under academic research program, residents of East South-Central region, living in a rural population <2,500 not adjacent to a metropolitan area, low income level, Medicaid recipients, high comorbidity index, small tumor, well-differentiated histology, residual tumor, and lack of receipt of chemotherapy and anti-hormonal therapy.

CONCLUSION

During the study period, the CALGB trial publication had a minimal impact on the rate of adjuvant RT use among elderly women with small, ER-positive breast cancers. Significant variation in RT usage existed across sociodemographic strata.

Abstract 2761: Adjuvant chemotherapy outcomes of node negative, T1a,T1b,T1c hormone receptor-negative HER2-positive breast cancer patients

Background: Patients (pts) with early stage HER2neu-positive breast cancers have a higher risk of recurrence and death compared to hormone receptor positive patients. NCCN guidelines recommends adjuvant chemotherapy for Stage II and above HER2-positive breast cancer patients. It is unclear what benefit patients with Stage I HER2-positive breast cancer receive from adjuvant chemotherapy. The current study evaluates the effects of adjuvant chemotherapy on the survival of early stage ER/PR negative, HER2-positive breast cancer patients registered to the National Cancer Data base (NCDB) from 2010-2012.

Patients and Methods: 3416 women from the NCDB were identified with Stage I ER, PR negative, HER2-positive breast cancer diagnosed between 2010-2012. The primary measured outcome was overall survival. Pts were grouped by tumor size (T1a,T1b,T1c) and adjuvant chemotherapy or no adjuvant chemotherapy. Additionally, patients were also grouped into lumpectomy with radiation and mastectomy with or without radiation. Adjusted variables included age, race, Charlson Comorbidity Index (CCI), payer status, income, education, distance travelled, diagnosing/treating facility and treatment delay. Multivariate Cox regression was used to investigate the effect of adjuvant chemotherapy on overall survival while adjusting for other factors.

Results: There were a total of 3416 patients, mean age at diagnosis of 57.9 (range 22-90). The mean age was 56.2 years for the chemotherapy group and 61.8 for the no chemotherapy group. Pathological stage distribution was T1a (24.9%), T1b (24.7%) and T1c (50.2%). Adjuvant chemotherapy was received by 49.5% of T1a, 83.5% of T1b and 95% of T1c pts. Mean patient follow up was 2.7 years (range 0.05-5 years)

In univariate analysis, the hazard ratio (HR) of death for chemotherapy vs no chemotherapy in each T stage was: T1a; 1.22 (0.46-3.28), T1b; 0.221 (0.095-0.512), T1c; 0.217 (0.094-0.498).

In multivariate analysis, adjusting for other factors in the model, HR of death was 0.51 (95%CI: 0.26-1.03) for chemotherapy vs no chemotherapy. The HR of death was 1.92 (95%CI: 1.11-3.32) for pts who received mastectomy without radiation compared to lumpectomy with radiation. In addition, we observed a HR of 5.16 for CCI score of 2 or above as compared to score of 0. There was no difference in outcome based on payer status or race.

Conclusion: Patients with early stage T1 a-c HER2-positive breast cancer had a marginal improvement in overall survival with the addition of chemotherapy. Patients who underwent lumpectomy with radiation were also found to have better overall survival compared to mastectomy without radiation. However, the relatively short follow up and the lack of cancer recurrence information preclude making definitive conclusions relative to adjuvant therapy for pts with these tumors. Longer follow-up and prospective controlled trials will be needed to quantify these potential benefits.

Citation Format: Anu Paul, Runhua Shi, Prakash Peddi, Gary Burton. Adjuvant chemotherapy outcomes of node negative, T1a,T1b,T1c hormone receptor-negative HER2-positive breast cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2761. doi:10.1158/1538-7445.AM2017-2761

Follicular dendritic sarcoma masquerading as fibrosing mediastinitis

Fibrosing mediastinitis (FM) is a rare disorder resulting from abnormal immunological-mediated fibro-proliferative reaction in the mediastinum. Here, we describe a case of a 46-year-old female with an incidentally found 11×9 cm posterior mediastinal mass. Multiple biopsies of this unresectable, 18-fluorodeoxyglucose avid mass revealed marked fibrosis without any evidence of malignancy, suggesting idiopathic fibrosing mediastinitis as our initial diagnosis. Multiple interventions including a trial of steroids, fluconazole, and azathioprine to target fibrosing mediastinitis were not successful. Repeat biopsy was consistent with primary mediastinal follicular dendritic cell sarcoma. The manuscript highlights the heightened need for suspecting occult malignancies in cases of FM presenting with an indeterminate cause.

Triple negative breast cancer (TNBC): Analysis of age and stage distribution and survival between African American and Caucasian women in a predominant low-income population

e12586

Background: Triple negative breast cancers (TNBC) represent roughly 15% of all breast cancer and are associated with decreased overall survival. A higher incidence of TNBC has been seen in younger and African American patients. We investigated the effect of age and race relative to outcomes of patients with TNBC seen at a state charity hospital system. Methods: This retrospective review identified 194 pts with TNBC diagnosed between 1993-2011 at LSUHSC-Shreveport, a state charity hospital. TNBC was defined as ER/PR both <1% and HER2neu not overexpressed by FISH analysis. The patient’s race, age at diagnosis, stage at diagnosis, treatment, relapse free survival (RFS), overall survival and survival following confirmed metastatic disease were analyzed. Results: There was no statistical difference in frequency of stage between groups. Although not statistically significant, there was a trend to worse RFS in AA and in young pts of both races. Younger age at diagnosis did have an inferior median survival as compared to older pts regardless of race or stage (p=0.0476). There was no difference in median survival following confirmation of metastatic disease between races (p=0.3574) or between age groups (p=0.8548); (median survival = 31 mos, 2.56-204 mos). Conclusions: In a predominantly low income patient population the incidence of TNBC was higher in the AA and in the young (age ≤ 50) as expected. There was no difference in stage or frequency within the populations. However, outcomes appeared to be worse in the younger pts and in AA patients with higher recurrence rate. Survival following first recurrence was similar regardless of age and race. Further analysis of etiologies for racial and age disparities is needed. [Table: see text]

Primary brain tumor and risk of venous thromboembolism

e13518

Background: Venous thromboembolism (VTE) is frequently associated with primary brain tumors (PBT). Brain tumors have been associated with higher rates of VTE in multiple studies. Studies comparing VTE incidence in meningioma (MEN), astrocytoma (AA), oligodendroglioma (OG) and glioblastoma multiforme (GBM) are lacking. The aim of this retrospective study is to report the VTE outcomes in all of the above brain tumors. Methods: Retrospective data from 476 patients with PBTs diagnosed between 1995-2015 at Louisiana State University Health Sciences Center-Shreveport was analyzed. The incidence of VTE (deep vein thrombosis or pulmonary embolism) was studied in these patients. Results: Out of 476 patients, 298 were females and 179 were male. One hundred and twenty seven (127) patients had GBM, 52 had AA, 33 had OG and 264 had MEN. Only two patients out of 264 with MEN had VTE (one patient had central line catheter associated DVT). VTE incidence did not correlate with the type of primary treatment i.e surgery verses radiation verses observation in this patient group. The incidence of VTE was 7.8 % in GBM patients. The risk of VTE in AA and OG patients were 7.7% and 9.0 % respectively. The VTE event in the OG, AA and GBM occurred during all phases of treatment including inpatient hospitalization for surgical resection, during concurrent chemo-radiation and in maintenance phase. Biopsy versus partial resection versus complete resection of GBM didn’t correlate with VTE occurrence. Conclusions: VTE is prevalent among adult patients with both low and high grade glial tumors. The thrombotic events occur during all phases of therapy indicating hypercoagulable state for many patients. Life-long anticoagulation may be necessary in these patients with thrombotic events. Thrombotic events in patients with MEN, however, are rare ( < 1%). MEN do not appear to be a hypercoagulable and life-long anticoagulation is probably unnecessary in those with VTE.

Reversal of isolated 20q deletion with vitamin B12 replacement in a patient with pernicious anaemia

Severe vitamin B₁₂ deficiency is well known to cause morphological alterations in bone marrow. In rare instances, these myelodysplastic and megaloblastic changes can coexist with cytogenetic abnormalities. Here, we report a case of a 38-year-old African-American woman with pernicious anaemia, who was found to have an isolated 20q deletion and which resolved after vitamin B₁₂ replacement. We also discuss various mechanisms in which vitamin B₁₂ deficiency can lead to chromosomal abnormalities. A literature review is also performed to evaluate various other chromosomal aberrations associated with B₁₂ deficiency.

Abstract P5-14-02: Triple negative breast cancer - Adjuvant chemotherapy use and survival outcomes in Stage IA disease

Background: The potential benefit of adjuvant chemotherapy in patients with Stage IA triple negative breast cancer (TNBC) has not been defined. In general, patients with T1a and T1b lesions have not been included in adjuvant chemotherapy trials and the inclusion of T1c tumors has been limited. In this study using National Cancer Data Base (NCDB) we investigated the actual use of adjuvant chemotherapy in Stage IA TNBC patients relative to tumor size (T1a, T1b, T1c) and report their survival outcomes.

Patients and Methods: Using NCDB we evaluated a cohort of 13,065 women with TNBC diagnosed between 2010-2012 who had American Joint Committee on Cancer Stage IA (node-negative with pathological T1a, T1b or T1c) tumors. Overall survival (OS) was the primary outcome variable. Based on the tumor size, patients were stratified on receipt of adjuvant chemotherapy or not. Patients were also stratified according to receipt of adjuvant radiation, radiation with boost, or none. Other adjusted variables included: age, race, Charlson comorbidity index, payer status, income, education, distance traveled, treating facility, and treatment delays. Multivariate Cox regression was employed to analyze the effect of adjuvant chemotherapy on overall survival.

Results: The mean patient age for the entire cohort was 59.2 years (range 22-90 years), 55.8 years for the chemotherapy group, and 67.8 years for the non-chemotherapy group. There were 1275 T1a, 3197 T1b, and 7729 T1c patients. Tumor size was a very strong predictor of survival. Compared to T1a tumors, HR for death was 1.43 (95% CI: 0.86 –2.37) for T1b tumors and 3.00 (95% CI: 1.86 – 4.83) for T1c tumors. Out of all T1a, T1b, and T1c tumors in this cohort, 48.1 %, 72.6%, and 89.3% of patients received adjuvant chemotherapy respectively. A hazard ratio (HR) of death was 0.42 (95% CI: 0.31 – 0.57) for all patients who received chemotherapy compared to non-chemotherapy group. 4-year OS by tumor size and chemotherapy usage is listed in the table indicating an absolute increase of OS with adjuvant chemotherapy employment. HR for death was 0.90 (CI: 0.62 – 1.31) with use of radiation only and 0.67 (95% CI: 0.53 – 0.85) with use of radiation with boost when compared to no radiation therapy.

4-year OS (in percentage) with and without adjuvant chemotherapy use for node-negative T1a, T1b, and T1c TNBCTumor sizeNo ChemotherapyChemotherapyP ValueT1a93.78 %98.36 %0.146T1b91.91 %97.10 %&lt;0.0001T1c80.62 %94.41 %&lt;0.0001

Conclusion: NCDB indicated that the majority of patients with Stage IA TNBC received adjuvant chemotherapy, including 48% of patients with T1a lesions. Our data analysis demonstrated a statistically significant 4-year OS benefit in patients with T1b and T1c tumors who received adjuvant chemotherapy compared to those who did not. The survival benefit of adjuvant chemotherapy in patients with T1a tumors, however, did not reach statistical significance. Prospective randomized trials could define the potential benefits of adjuvant chemotherapy in patients with Stage IA TNBC, particularly for those with T1a and T1b tumors.

Citation Format: Patel AN, Shi R, Peddi P, Burton GV. Triple negative breast cancer - Adjuvant chemotherapy use and survival outcomes in Stage IA disease [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-14-02.

Recurrent Malignant Melanoma Presenting as Isolated Pleural Metastases in a Patient with Chronic Lymphocytic Leukemia

Isolated pleural metastasis with pleural effusion is a rare occurrence in malignant melanoma. We report an unusual case of a patient with chronic lymphocytic leukemia (CLL) and recurrent pleural effusions. The pleural fluid cytology and immunohistochemistry profile were consistent with the diagnosis of CLL. However, chemotherapy with pentostatin, cyclophosphamide, and rituximab did not result in any meaningful clinical response. A video-assisted thoracoscopic surgery and biopsy of the affected nodular parietal layer of the pleura were consistent with malignant melanoma. Our case underlines the importance of having a suspicion for secondary causes of effusion in patients with CLL. We briefly discuss the mechanisms of an increased incidence of secondary cancers in CLL and the diagnosis of isolated pleural metastases in malignant melanoma.

Regression of a glioblastoma multiforme: spontaneous versus a potential antineoplastic effect of dexamethasone and levetiracetam

Patients with grade IV astrocytoma or glioblastoma multiforme (GBM) have a median survival of <12 months, increased to 14.6 months by maximal safe resection with radiation and temozolamide. In the absence of chemotherapy, radiotherapy or chemoradiotherapy, spontaneous regression of GBM or regression while only being on dexamethasone (DEX) and levetiracetam (LEV) have seldom been reported. Here, we present a case of a patient who had significant regression of the GBM with DEX and LEV alone. In this study, we hypothesise a plausible antineoplastic role of DEX and or LEV in GBM and highlight molecular, preclinical and clinical studies supporting this role.

Immune checkpoint inhibitors: the new frontier in non-small-cell lung cancer treatment

Lung cancer is the major cause for cancer-related death in the US. Although advances in chemotherapy and targeted therapy have improved the outcome of metastatic non-small-cell lung cancer, its prognosis remains dismal. A deeper understanding of the complex interaction between the immune system and tumor microenvironment has identified immune checkpoint inhibitors as new avenue of immunotherapy. Rather than acting directly on the tumor, these therapies work by removing the inhibition exerted by tumor cell or other immune cells on the immune system, promoting antitumoral immune response. To date, two programmed death-1 inhibitors, namely nivolumab and pembrolizumab, have received the US Food and Drug Administration approval for the treatment of advanced non-small-cell lung cancer that failed platinum-based chemotherapy. This manuscript provides a brief overview of the pathophysiology of cancer immune evasion, summarizes pertinent data on completed and ongoing clinical trials involving checkpoint inhibitors, discusses the different strategies to optimize their function, and outlines various challenges that are faced in this promising yet evolving field.

Positive surgical margins contribute to the survival paradox between patients with stage IIB/C (T4N0) and stage IIIA (T1-2N1, T1N2a) colon cancer

BACKGROUND

The underlying reasons for the survival paradox between stage IIB/C and stage IIIA colon cancer are elusive. We hypothesized that positive margins contribute to this paradox.

METHODS

We evaluated a cohort of 16,471 patients with stage IIIA and stage IIB/C colon cancer from 709,583 cases diagnosed between 2003-2012 in the National Cancer Data Base. All patients had chemotherapy, and all stage IIB/C patients had ≥12 lymph nodes retrieved. Patients with stage IIIA were subdivided further into those with <12 lymph nodes retrieved and those with ≥12 lymph nodes retrieved. Univariable and multivariable survival analyses were used.

RESULTS

The 5-year overall survival rate was 70.8% for stage IIB/C, 81.6% for stage IIIA with <12 lymph nodes, and 85.6% for stage IIIA with ≥12 lymph nodes (P < .0001). The 5-year overall survival rate was 84.3% for stage IIIA with no residual tumor, 74.8% for stage IIIA with residual tumor, 73.3% for stage IIB/C with no residual tumor, and 60.5% for stage IIB/C with residual tumor (P < .0001). Independent predictors (P < .01) of poor overall survival include stage IIB/C, advanced age, African American ethnicity, community cancer program, uninsured and Medicaid, low education level, high comorbidity index, and positive surgical margins.

CONCLUSION

Positive surgical margins may contribute to the survival paradox between stage IIB/C and stage IIIA colon cancer patients.

Poor survival in stage IIB/C (T4N0) compared to stage IIIA (T1-2 N1, T1N2a) colon cancer persists even after adjusting for adequate lymph nodes retrieved and receipt of adjuvant chemotherapy

Background

A survival paradox between Stage IIB/C and Stage IIIA colon cancers exists. It is unclear how adequate lymph nodes dissection (LN) and post-surgery chemotherapy contribute to the survival paradox. We intended to assess the impact of these two factors on the survival paradox.

Results

We evaluated 34,999 patients diagnosed with stage IIIA or stage IIB/C colon cancer in 2003–2012 from the National Cancer Data Base. The 5-year overall survival (OS) was 73.5 % for stage IIIA and 51.1 % for stage IIB/C (P < 0.0001). The 5-year OS was 84.1 % for stage IIIA with post-surgery chemotherapy, 70.8 % for stage IIB/C with ≥ 12 LNs retrieved with chemotherapy, 53.9 % for stage IIB/C < 12 LNs with chemotherapy, 49.5 % for stage IIIA without chemotherapy, 43.7 % for stage IIB/C ≥ 12 LNs retrieved without chemotherapy, to 27.7 % for stage IIB/C < 12 LNs without chemotherapy. Even among stage IIB/C who had optimal treatment (≥12 LNs retrieved, received chemotherapy), OS remains lower than stage IIIA with chemotherapy. After adjusting LN dissection and chemotherapy in addition to the adjustment of other clinical factors, the survival paradox was reduced from HR = 1.76 (95 % CI: 1.68–1.85) to HR 1.51 (95 % CI: 1.44–1.59).

Conclusions

LN dissection and post-surgery chemotherapy partially explained the survival paradox. More research is warranted to identify other factors that contribute to this paradox. Future iteration of TNM staging system should take this into consideration.

Should Sentinel Lymph Node Biopsy for Patients with Early Breast Cancer Be Abandoned? Not So Fast

As major advances are made in the management of early breast cancer, the role of sentinel lymph node biopsy (SLNBx) has been called into question. However, before abandoning SLNBx, a critical appraisal of its role should be done because we believe that it remains a critical component of care, especially when tailoring patient's adjuvant therapy. This commentary provides cogent arguments in favor of SLNBx in the management of patients with early breast cancer.

Histiocytic sarcoma as a secondary malignancy: pathobiology, diagnosis, and treatment

Histiocytic sarcoma (HS) is an extremely rare non-Langerhans cell disorder with an aggressive course and limited treatment options. Recent advances in molecular/genetic sequencing have suggested a common clonal origin between various hematolymphoid disorders and cases of secondary HS. Deriving conclusions from previously reported cases of HS arising secondarily to certain hematolymphoid disorders, here we have tried to provide insight into the mechanisms influencing this evolution. We also discuss a clinical case of a 72-year-old man with a diagnosis of chronic myeloid leukemia (CML), presenting subsequently with a heterogeneous liver mass positive with a diagnosis of HS. The liver mass showed a retained BCR-ABL1 translocation suggesting clonality between the CML and HS. As seen in our case and other reported cases of HS derived secondarily, the concurrent expression of immunoglobulin heavy (IGH)-/light-chain rearrangements or cytogenetic markers common to the primary malignancy suggests an evolutionary mechanism involving lineage switching that could potentially be influenced by genetic or epigenetic cues which may occur at the level of a progenitor or the malignant cell itself.

Exceptional response to cetuximab monotherapy in a patient with metastatic oropharyngeal squamous cell carcinoma: a molecular insight

Background

Metastatic head and neck squamous cell carcinoma (HNSCC) carries a very poor prognosis. A better understanding of the molecular driver of the disease and the identification of biomarkers of response remain paramount for an effective personalized therapy.

Case report

We report an original case of a 56-year-old patient diagnosed with metastatic HNSCC to both kidneys, who experienced a long-lasting complete response to a single-agent cetuximab, a monoclonal antibody-targeting EGFR. Comprehensive multiplatform biomarker analysis of the tumor revealed the presence of phosphatidyl-inositol 3 kinase mutation, EGFR overexpression, and the absence of PD-1/PD-L1 expression. Since PI3K, a downstream effector of EGFR, is activated, the tumor regression may have occurred mainly through a cetuximab-induced immune-mediated response, rather than EGFR signal blockade. It is plausible that this effect was enhanced by the lack of PD-1 and PD-L1 expression.

Conclusion

Our case proposes that the absence of PD-1 and PD-L1 expression in conjunction with EGFR overexpression may correlate with better response to cetuximab in HNSCC. This hypothesis needs to be examined through a large clinical trial.

Charcot's osteoarthropathy mimicking an osteosarcoma of humerus

Charcot's arthropathy or neuropathic osteoarthropathy is a form of destructive arthropathy associated with decreased sensory innervation. We present an unusual case of a patient referred to oncology clinic for further evaluation of a spindle cell neoplasm of the humerus concerning for malignancy. The mass presented as a lytic lesion associated with a right humerus fracture. This was later diagnosed as Charcot's shoulder secondary to cervical syringomyelia. A detailed case report and discussion are presented here.

Effect of Postmastectomy Radiation on Survival of AJCC pN2/N3 Breast Cancer Patients

BACKGROUND

The effectiveness of postmastectomy radiation (PMRT) in breast cancer patients with N2 and N3 nodal status is often evaluated in combination with other postmastectomy adjuvant treatments. To account for interaction effects and determine the individual impact of PMRT alone, the National Cancer Data Base (NCDB) was analyzed from 2004-2011.

PATIENTS AND METHODS

We evaluated a cohort of 38,442 women diagnosed with pathological stage N2/N3 breast cancer who underwent mastectomy between 2004 and 2011 from the NCDB. Overall survival was the outcome variable; primary predictor variable was treatment (PMRT, adjuvant anti-hormonal therapy, and adjuvant chemotherapy). Additional variables addressed and adjusted for included: age, race, Charlson Comorbidity index, education, income, payer status, distance traveled, facility type, diagnosing/treating facility, treatment delay, grade of tumor, tumor size, and stage at diagnosis, tumor histology, ER/PR status, and lymph node invasion as well as PMRT boost and dosage. Multivariate Cox regression was used to investigate the effect of PMRT on overall survival while adjusting for secondary predictive factors.

RESULTS

The majority of patients received one or more postmastectomy procedures such as radiation (69.31%), chemotherapy (88.79%), and/or hormone therapy (62.66%). The median overall survival for all patients was 8.41 years. In multivariate analysis, effects of treatment on survival were significant for chemotherapy alone, hormonal therapy alone, and a combination of PMRT with either chemotherapy, hormonal therapy, or both. Compared to patients without treatment, patients who received PMRT alone were not significantly associated with an increased risk of death; patients who received hormone therapy alone or chemotherapy alone had a reduced risk of death by 15% and 31%, respectively. With the combination of all three treatments, risk of death was reduced by 64%.

CONCLUSION

PMRT was not found to be a significant predictor of risk of death for pN2/N3 breast cancer patients when adjusting for socioeconomic factors, disease characteristics, and interaction effects of chemotherapy and hormonal therapy. The benefit of PMRT in addition to chemotherapy, hormonal therapy or both on overall survival seems to be marginal and not statistically significant.

Cisplatin, cetuximab, and radiation in locally advanced head and neck squamous cell cancer: a retrospective review

Efficacy of cisplatin versus cetuximab with radiation in locally advanced head and neck cancer (LAHNC) was evaluated. A total of 96 patients with newly diagnosed LAHNC treated at our institution between 2006 and 2011 with concurrent radiation and cisplatin (group A, n = 45), cetuximab (group B, n = 24), or started with cisplatin but switched to cetuximab because of toxicity (group C, n = 27) were reviewed. Chi-square test, analysis of variance, and log-rank test were used for analysis. The three groups had similar baseline characteristics, except for median age, T stage, albumin levels, hemoglobin levels, performance status, and comorbidities. A complete response (CR) was seen in 77%, 17%, and 67% of patients (P < 0.001), respectively. There was no significant difference in median overall survival (OS) between groups A and C. The median OS for groups A and C was not reached (>65 months), even though it was significantly longer than median OS for group B (11.6 months; P ≤ 0.001). The 2-year OS in groups A and C is significantly higher than that in group B (70% for groups A and C, 22% for group B). There is no significant difference in progression-free survival (PFS) between groups A and C. The median PFS for these groups was not reached (>62 months), and is significantly longer than that for group B (4.3 months; P ≤ 0.001). The 2-year PFS of group A (67%) and group C (76%) was significantly longer than that of group B (20%). Cisplatin with radiation appears to be more efficacious even in suboptimal dosing than cetuximab with radiation in LAHNC but the two groups were not well matched.

SUV max of the most intense lesion on fdgpet/CT scan at baseline as a potential prognostic factor in stage IV (NSCLC): A retrospective review

e19070

Background: Lung cancer is the leading cause of mortality in United States and worldwide. Stage IV lung cancer has poor prognosis with 5-year survival of 2%. Limited numbers of factors are known to predict survival in stage IV NSCLC (Non Small Cell Lung Cancer) including stage at diagnosis, Performance Status (PS), genomic expression profile. Earlier studies have found SUV max (Maximum Standardized Uptake Value) of primary lung tumor on FDGPET/CT (Fluoro Deoxy Glucose –Positron Emission Tomography/Computed Tomography) correlates with tumor doubling time and survival. However prior studies included stage I-IV NSCLC patients and SUVmax of primary lung tumor. Hence we performed this study with only clinical stage IVNSCLC who underwent FDGPET/CT scan at baseline to determine whether SUVmax value of most intense lesion has any prognostic significance. Methods: Retrospective review identified 46 patients (September 2004- September 2011) that were diagnosed with stage IV NSCLC at our institution. SUVmax of most intense lesion on FDG PET/CT scan was determined utilizing an automated program on a dedicated PET/CT workstation by a single nuclear medicine specialist. Cox regression analysis and Log-rank test were used to analyze data. Results: Descriptive statistics: Median age 61.6 (43.8-77.8), Females 17 (36%), African Americans 26 (56%), Performance status 0-1=36 (80%), number of metastatic sites 1-2=30 (65%), Adenocarcinoma 32 (70%), Chemotherapy 31 (61%), SUV max- primary (65%), other sites (35%). The patient population was subdivided into two groups using the median SUVmax of 17.8. The median survival of patients having SUV max ≤17.8 and SUVmax > 17.8 was 13.4 months and 4.5 months respectively (P =0.0269). Multivariate analysis indicated PS (HR=2.8), any chemotherapy (HR=2.56) and SUV max ≤ 17.8 (HR=1.98, P=0.04) predicted survival. Conclusions: SUV max of the most intense lesion at the time of presentation predicts worse outcome in stage IVNSCLC and needs to be validated in a prospective study. PETCT may be able to predict the areas that harbor resistant clones of cells, described in previous studies as tumor heterogeneity, which may confer prognostic significance.

Cisplatin (CDDP) and radiation versus cetuximab (Cx) and radiation in locally advanced head and neck squamous cell cancer (SCHNC): A retrospective review

e16009

Background: SCHNC is a common malignancy and approximately 60% of patients present with locally advanced disease. There is paucity of data directly comparing Cx and CDDP with concurrent radiation in locally advanced SCHNC. We retrospectively reviewed charts of patients treated with CDDP and/or Cx along with radiation in locally advanced SCHNC comparing efficacy and outcomes in an academic cancer center. Methods: Ninety-five patients with locally advanced SCHNC were treated with concurrent CDDP (100 mg/m2 day 1, 22, 43) or Cx (400mg/m2 on day -7 and 250mg/m2 weekly) at our institution between January 2006 and June 2011. Forty-four patients were treated with CDDP (group A), 24 with Cx (group B) and 27 were initially started on CDDP but were switched to Cx secondary to toxicity (group C). All patients received concurrent radiation treatments (66-70 Gy, 2.0 Gy/fraction). The selection of CDDP versus Cx was largely based on ECOG performance status (PS) and baseline renal function of the patients. Chi-square test, analysis of variance, and log-rank test was used for analysis. The three groups had similar baseline characteristics except for mean age of 61, 56 and 55 years in group A, B and C respectively; T4 tumors consisted of 44%, 75% and 41% in groups A, B and C respectively. Groups A, B and C had a combined ECOG 0 and I (PS) of 93%, 75% and 92%. Patients with ECOG III PS were excluded. Results: Oropharynx was the most common treated site (38%) followed by Larynx (35%). Complete response (CR) was seen in 77%, 17% and 67% in groups A, B and C respectively (P<0.001). Median progression free survival (PFS) was 16.6, 4.3 and 22.8 in groups A, B and C respectively (P<0.001) and median overall survival (OS) was >35, 11.6 and >32 months in groups A, B and C respectively (P<0.0001). Conclusions: Concurrent CDDP with radiation leads to better response rate PFS and OS as opposed to Cx though many patients treated with CDDP could not complete treatment due to toxicity. Randomized trial comparing the two should be considered.

P5-01-19: Endothelin-1 Expression in Breast Cancer Tissue, Surrounding Stroma, Correlation with Tumor Microvessel Density and Clinical Outcome

Background: Endothelin-1 (ET-1) is a peptide which regulates normal biological processes such as vascular tone. In addition, endothelin signaling pathway is dysregulated in pathophysiological conditions such as cancer and fibrosis. It has been shown that endothelin-1 is expressed in breast cancer tissue but little is known with regard to ET-1 expression in surrounding tumor stroma. In the present study, we investigated ET-1 expression in breast tumor cells, surrounding stroma, association with tumor microvessel density (MVD) and impact on clinical outcome.

Materials and Methods: We conducted a retrospective, multicenter study. Patients from 3 medical centers with histologically documented stage I-III invasive breast cancer were included in the study. Paraffin embedded formalin fixed breast cancer tissue and surrounding stroma were evaluated for ET-1 and CD34 (marker for MVD) by IHC. ET-1 cytoplasmic expression was scored as positive (3+ by IHC) or negative (0, 1+, 2+). Stained vessels by CD34 were counted in five consecutive fields at 40 x magnification and their mean was recorded. Demographics, clinical data and recurrence free interval (RFI) in months were available for statistical analysis.

Results: The study included 92 patients with average age of 55 years at diagnosis. Median follow up of patients at the time of analysis was 72 months. Total of 29 patients experienced disease progression ( 17 locoregional and 12 distant). Tumor ET-1 expression positively correlated with earlier stage: odds ratio (OR) = 22 for stage I and OR=20 for stage II as compared with stage III. Positive ET-1 staining in tumor was detected in 72.8 % of cases, while ET-1 positive expression in stroma was detected only in 6.5% of cases. Interestingly, all ET-1 stroma positive tumors were estrogen receptor (ER) positive. The means of CD34 were not different according to ET-1 expression either in the tumor or stroma. Triple negative breast cancer tumors exhibited higher MVD (p=0.0177). In the logistic regression model relating ET-1 expression in tumor to clinical variables, ET-1 positive tumors showed a trend for the association with higher relapse rate (p=0.058). Multivariate analysis suggested that there was no significant difference in the recurrence free interval (RFI) between the ET-1 positive and ET-1 negative groups (long-rank test p-value = 0.71). Survival analysis identified stage as a significant predictor of RFI in the Cox proportional hazard model that included ET-1 expression and other clinical variables.

Conclusions: The significant predictor for ET-1 expression in the tumor was early stage. High tumor ET-1 expression was more common in patients who experienced breast cancer recurrence. No association was found between ET-1 expression and MVD, and between ET-1 expression and time to recurrence. Further studies with larger sample size are needed to better delineate a role of ET-1 as prognostic biomarker in early stage breast cancer.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-01-19.

DNA-PKcs deficiency leads to persistence of oxidatively induced clustered DNA lesions in human tumor cells

DNA-dependent protein kinase (DNA-PK) is a key non-homologous-end-joining (NHEJ) nuclear serine/threonine protein kinase involved in various DNA metabolic and damage signaling pathways contributing to the maintenance of genomic stability and prevention of cancer. To examine the role of DNA-PK in processing of non-DSB clustered DNA damage, we have used three models of DNA-PK deficiency, i.e., chemical inactivation of its kinase activity by the novel inhibitors IC86621 and NU7026, knockdown and complete absence of the protein in human breast cancer (MCF-7) and glioblastoma cell lines (MO59-J/K). A compromised DNA-PK repair pathway led to the accumulation of clustered DNA lesions induced by gamma-rays. Tumor cells lacking protein expression or with inhibited kinase activity showed a marked decrease in their ability to process oxidatively induced non-DSB clustered DNA lesions measured using a modified version of pulsed-field gel electrophoresis or single-cell gel electrophoresis (comet assay). In all cases, DNA-PK inactivation led to a higher level of lesion persistence even after 24-72h of repair. We suggest a model in which DNA-PK deficiency affects the processing of these clusters first by compromising base excision repair and second by the presence of catalytically inactive DNA-PK inhibiting the efficient processing of these lesions owing to the failure of DNA-PK to disassociate from the DNA ends. The information rendered will be important for understanding not only cancer etiology in the presence of an NHEJ deficiency but also cancer treatments based on the induction of oxidative stress and inhibition of cluster repair.

Processing of clustered DNA damage in human breast cancer cells MCF-7 with partial DNA-PKcs deficiency

Complex DNA damage such as double strand breaks (DSBs) and non-DSB bistranded oxidative clustered DNA lesions (OCDL) (two or more DNA lesions within a short DNA fragment of 1-10bp on opposing DNA strands) are considered the hallmark of ionizing radiation. Clustered DNA lesions are hypothesized to be repair-resistant lesions challenging the repair mechanisms of the cell. The DNA-dependent protein kinase catalytic subunit (DNA-PKcs) plays an important role during the processing of DSBs. To evaluate the role of DNA-PKcs in the processing of complex DNA damage in human MCF-7 breast cancer cells we used small interfering RNAs (siRNAs) to target the silencing of the gene Prkdc coding for DNA-PKcs. MCF-7 cells with knockdown DNA-PKcs expression showed a marked decrease in their efficiency to process DSBs and OCDL after exposure to radiotherapy-relevant gamma ray doses. For the detection and measurement of complex DSBs and OCDL, we used the gamma-H2AX assay and an adaptation of pulsed field gel electrophoresis with Escherichia coli repair enzymes as DNA damage probes. An accumulation of all types of DNA damage was detected for the siRNA-treated MCF-7 cells compared to controls. These findings point to the important role of DNA-PKcs in the processing of complex DNA damage and its potential association with breast cancer development.

Induction and processing of complex DNA damage in human breast cancer cells MCF-7 and nonmalignant MCF-10A cells

Oxidatively induced stress and DNA damage have been associated with various human pathophysiological conditions, including cancer and aging. Complex DNA damage such as double-strand breaks (DSBs) and non-DSB bistranded oxidatively induced clustered DNA lesions (OCDL) (two or more DNA lesions within a short DNA fragment of 1-10 bp on opposing DNA strands) are hypothesized to be repair-resistant lesions challenging the repair mechanisms of the cell. To evaluate the induction and processing of complex DNA damage in breast cancer cells exposed to radiotherapy-relevant gamma-ray doses, we measured single-strand breaks (SSBs), DSBs, and OCDL in MCF-7 and HCC1937 malignant cells as well as MCF-10A nonmalignant human breast cells. For the detection and measurement of SSBs, DSBs, and OCDL, we used the alkaline single-cell gel electrophoresis, gamma-H2AX assay, and an adaptation of pulsed-field gel electrophoresis with E. coli repair enzymes as DNA damage probes. Increased levels for most types of DNA damage were detected in MCF-7 cells while the processing of DSBs and OCDL was deficient in these cells compared to MCF-10A cells. Furthermore, the total antioxidant capacity of MCF-7 cells was lower compared to their nonmalignant counterparts. These findings point to the important role of complex DNA damage in breast cancer and its potential association with breast cancer development especially in the case of deficient BRCA1 expression.

Identification and biological evaluation of a novel and potent small molecule radiation sensitizer via an unbiased screen of a chemical library

For patients with solid tumors, the tolerance of surrounding tissues often limits the dose of radiation that can be delivered. Thus, agents that preferentially increase the cytotoxic effects of radiation toward tumor cells would significantly alter the therapeutic ratio and improve patient survival. Using a high-throughput, unbiased screening approach, we have identified 4'-bromo-3'-nitropropiophenone (NS-123) as a radiosensitizer of human glioma cells in vitro and in vivo. NS-123 radiosensitized U251 glioma cells in a dose-dependent and time-dependent manner, with dose enhancement ratios ranging from 1.3 to 2.0. HT-29 colorectal carcinoma and A549 lung adenocarcinoma cells were also radiosensitized by NS-123 in vitro, whereas NS-123 did not increase the radiation sensitivity of normal human astrocytes or developmental abnormalities or lethality of irradiated Zebrafish embryos. In a novel xenograft model of U251 cells implanted into Zebrafish embryos, NS-123 enhanced the tumor growth-inhibitory effects of ionizing radiation (IR) with no apparent effect on embryo development. Similar results were obtained using a mouse tumor xenograft model in which NS-123 sensitized U251 tumors to IR while exhibiting no overt toxicity. In vitro pretreatment with NS-123 resulted in accumulation of unrepaired IR-induced DNA strand breaks and prolonged phosphorylation of the surrogate markers of DNA damage H2AX, ataxia telangiectasia mutated protein, DNA-dependent protein kinase, and CHK2 after IR, suggesting that NS-123 inhibits a critical step in the DNA repair pathway. These results show the potential of this cell-based, high-throughput screening method to identify novel radiosensitizers and suggest that NS-123 and similar nitrophenol compounds may be effective in antiglioma modalities.