Larissa J. Lee

The Androgen Receptor Recruits Nuclear Receptor CoRepressor (N-CoR) in the Presence of Mifepristone via Its N and C Termini Revealing a Novel Molecular Mechanism for Androgen Receptor Antagonists

The androgen receptor (AR) activates target gene expression in the presence of agonist ligands via the recruitment of transcriptional coactivators, but recent work shows that overexpression of the nuclear corepressors NCoR and SMRT attenuates this agonist-mediated AR activation. Here we demonstrate using NCoR siRNA and chromatin immunoprecipitation that endogenous NCoR is recruited to and represses the dihydrotestosterone (DHT)-liganded AR. Furthermore this study shows that NCoR and coactivators compete for AR in the presence of DHT. AR antagonists such as bicalutamide that are currently in use for prostate cancer treatment can also mediate NCoR recruitment, but mifepristone (RU486) at nanomolar concentrations is unique in its ability to markedly enhance the AR-NCoR interaction. The RU486-liganded AR interacted with a C-terminal fragment of NCoR, and this interaction was mediated by the two most C-terminal nuclear receptor interacting domains (RIDs) present in NCoR. Significantly, in addition to the AR ligand binding domain, the AR N terminus was also required for this interaction. Mutagenesis studies demonstrate that the N-terminal surface of the AR-mediating NCoR recruitment was distinct from tau5 and from the FXXLF motif that mediates agonist-induced N-C-terminal interaction. Taken together these data demonstrate that NCoR is a physiological regulator of the AR and reveal a new mechanism for AR antagonism that may be exploited for the development of more potent AR antagonists.

The nuclear corepressor, NCoR, regulates thyroid hormone action in vivo

The thyroid hormone receptor (TR) has been proposed to regulate expression of target genes in the absence of triiodothyronine (T3) through the recruitment of the corepressors, NCoR and SMRT. Thus, NCoR and SMRT may play an essential role in thyroid hormone action, although this has never been tested in vivo. To accomplish this, we developed mice that express in the liver a mutant NCoR protein (L-NCoRΔID) that cannot interact with the TR. L-NCoRΔID mice appear grossly normal, however, when made hypothyroid the repression of many positively regulated T3-target genes is abrogated, demonstrating that NCoR plays a specific and sufficient role in repression by TR in the absence of T3. Remarkably, in the euthyroid state, expression of many T3-targets is also up-regulated in L-NCoRΔID mice, demonstrating that NCoR also determines the magnitude of the response to T3 in euthyroid animals. Although positive T3 targets were up-regulated in L-NCoRΔID mice in the hypo- and euthyroid state, there was little effect seen on negatively regulated T3 target genes. Thus, NCoR is a specific regulator of T3-action in vivo and mediates repression by the unliganded TR in hypothyroidism. Furthermore, NCoR appears to play a key role in determining the tissue-specific responses to similar levels of circulating T3. Interestingly, NCoR recruitment to LXR is also impaired in this model, leading to activation of LXR-target genes, further demonstrating that NCoR recruitment regulates multiple nuclear receptor signaling pathways.

Comparison and consensus guidelines for delineation of clinical target volume for CT- and MR-based brachytherapy in locally advanced cervical cancer

OBJECTIVE To create and compare consensus clinical target volume (CTV) contours for computed tomography (CT) and 3-Tesla (3-T) magnetic resonance (MR) image-based cervical-cancer brachytherapy. METHODS AND MATERIALS Twenty-three experts in gynecologic radiation oncology contoured the same 3 cervical cancer brachytherapy cases: 1 stage IIB near-complete response (CR) case with a tandem and ovoid, 1 stage IIB partial response (PR) case with tandem and ovoid with needles, and 1 stage IB2 CR case with a tandem and ring applicator. The CT contours were completed before the MRI contours. These were analyzed for consistency and clarity of target delineation using an expectation maximization algorithm for simultaneous truth and performance level estimation (STAPLE), with κ statistics as a measure of agreement between participants. The conformity index was calculated for each of the 6 data sets. Dice coefficients were generated to compare the CT and MR contours of the same case. RESULTS For all 3 cases, the mean tumor volume was smaller on MR than on CT (P<.001). The κ and conformity index estimates were slightly higher for CT, indicating a higher level of agreement on CT. The Dice coefficients were 89% for the stage IB2 case with a CR, 74% for the stage IIB case with a PR, and 57% for the stage IIB case with a CR. CONCLUSION In a comparison of MR-contoured with CT-contoured CTV volumes, the higher level of agreement on CT may be due to the more distinct contrast medium visible on the images at the time of brachytherapy. MR at the time of brachytherapy may be of greatest benefit in patients with large tumors with parametrial extension that have a partial or complete response to external beam. On the basis of these results, a 95% consensus volume was generated for CT and for MR. Online contouring atlases are available for instruction at http://www.nrgoncology.org/Resources/ContouringAtlases/GYNCervicalBrachytherapy.aspx.

Clinical outcomes of high-dose-rate interstitial gynecologic brachytherapy using real-time CT guidance

PURPOSE To evaluate clinical outcomes of CT-guided high-dose-rate (HDR) interstitial brachytherapy for primary and recurrent gynecologic cancer. METHODS AND MATERIALS Records were reviewed for 68 women (34 with primary disease and 34 with recurrence) treated with CT-guided HDR interstitial brachytherapy between May 2005 and September 2011. Interstitial application was performed under general anesthesia using an iterative approach of catheter insertion and adjustment with serial image acquisition by CT in a dedicated brachytherapy suite. The median fractional brachytherapy dose was 3.9Gy delivered twice daily in seven fractions. The median cumulative dose in equivalent 2-Gy fractions was 74.8Gy. Actuarial survival estimates were calculated using the Kaplan-Meier method, and toxicity was reported by Common Toxicity Criteria. RESULTS Primary disease sites were endometrial (34), cervical (17), vaginal (11), ovarian (3), and vulvar (3). Median age was 61.5 years, and tumor size at diagnosis was 3.4cm. Median D90 and V100 were 73.6Gy and 87.5%, respectively; median D2cc for bladder, rectum, and sigmoid were 67.1, 64.6, and 53.7Gy, respectively. With a median followup of 17 months, actuarial rates of local control, progression-free survival, and overall survival at 2 years for all patients were 86%, 60%, and 64%, respectively. There were 9 grade 3 late toxicities (six gastrointestinal and three vulvovaginal). CONCLUSIONS HDR interstitial brachytherapy with CT-guided catheter placement results in acceptable local control, toxicity, and survival rates for women with primary or recurrent gynecologic cancer. Durable pelvic control may be achieved in most patients with this specialized brachytherapy technique.

Clinical outcome of triple negative breast cancer in BRCA1 mutation carriers and noncarriers

Women with BRCA1 mutations develop breast cancer with similar pathologic features to sporadic triple negative (TN) breast cancer, a subtype associated with early disease relapse and poor outcome. The clinical outcome of women with and without BRCA1 mutations who had TN breast cancer treated with conventional chemotherapy were compared.

American Brachytherapy Society consensus guidelines for locally advanced carcinoma of the cervix. Part III: Low-dose-rate and pulsed-dose-rate brachytherapy

PURPOSE To develop a guideline for quality practice of low-dose-rate (LDR) and pulsed-dose-rate (PDR) brachytherapy for locally advanced cervical cancer. METHODS Members of the American Brachytherapy Society (ABS) with expertise in cervical cancer brachytherapy formulated updated guidelines for LDR and PDR brachytherapy for locally advanced (International Federation of Gynecology and Obstetrics [FIGO] Stages IB2-IVA) cervical cancer based on literature review and clinical experience. RESULTS The ABS strongly recommends the use of brachytherapy as a component of the definitive treatment of locally advanced cervical carcinoma. Precise applicator placement is necessary to maximize the probability of achieving local control without major side effects. The ABS recommends a cumulative delivered dose of approximately 80-90Gy for definitive treatment. Dosimetry must be performed after each insertion before treatment delivery. The dose delivered to point A should be reported for all intracavitary brachytherapy applications regardless of treatment planning technique. The ABS also recommends adoption of the Groupe Européen de Curiethérapie-European Society for Therapeutic Radiology and Oncology guidelines for contouring, image-based treatment planning and dose reporting. Interstitial brachytherapy may be considered for a small proportion of patients whose disease cannot be adequately encompassed by intracavitary application and should be performed by practitioners with special expertise in these procedures. Quality management measures must be performed, and follow-up information should also be obtained. CONCLUSIONS Updated ABS guidelines are provided for LDR and PDR brachytherapy for locally advanced cervical cancer. Practitioners and cooperative groups are encouraged to use these guidelines to formulate their clinical practices and to adopt dose-reporting policies that are critical for outcome analysis.

Predictors of Toxicity After Image-guided High-dose-rate Interstitial Brachytherapy for Gynecologic Cancer

PURPOSE To identify predictors of grade 3-4 complications and grade 2-4 rectal toxicity after three-dimensional image-guided high-dose-rate (HDR) interstitial brachytherapy for gynecologic cancer. METHODS AND MATERIALS Records were reviewed for 51 women (22 with primary disease and 29 with recurrence) treated with HDR interstitial brachytherapy. A single interstitial insertion was performed with image guidance by computed tomography (n = 43) or magnetic resonance imaging (n = 8). The median delivered dose in equivalent 2-Gy fractions was 72.0 Gy (45 Gy for external-beam radiation therapy and 24 Gy for brachytherapy). Toxicity was reported according to the Common Toxicity Criteria for Adverse Events. Actuarial toxicity estimates were calculated by the Kaplan-Meier method. RESULTS At diagnosis, the median patient age was 62 years and the median tumor size was 3.8 cm. The median D90 and V100 were 71.4 Gy and 89.5%; the median D2cc for the bladder, rectum, and sigmoid were 64.6 Gy, 61.0 Gy, and 52.7 Gy, respectively. The actuarial rates of all grade 3-4 complications at 2 years were 20% gastrointestinal, 9% vaginal, 6% skin, 3% musculoskeletal, and 2% lymphatic. There were no grade 3-4 genitourinary complications and no grade 5 toxicities. Grade 2-4 rectal toxicity was observed in 10 patients, and grade 3-4 complications in 4; all cases were proctitis with the exception of 1 rectal fistula. D2cc for rectum was higher for patients with grade 2-4 (68 Gy vs 57 Gy for grade 0-1, P=.03) and grade 3-4 (73 Gy vs 58 Gy for grade 0-2, P=.02) rectal toxicity. The estimated dose that resulted in a 10% risk of grade 2-4 rectal toxicity was 61.8 Gy (95% confidence interval, 51.5-72.2 Gy). DISCUSSION Image-guided HDR interstitial brachytherapy results in acceptable toxicity for women with primary or recurrent gynecologic cancer. D2cc for the rectum is a reliable predictor of late rectal complications. Three-dimensional-based treatment planning should be performed to ensure adequate tumor coverage while minimizing the D2cc to the rectum.

Genetic Basis for PD-L1 Expression in Squamous Cell Carcinomas of the Cervix and Vulva

IMPORTANCE Patients with squamous cell carcinoma (SCC) of the cervix or vulva have limited therapeutic options, and the potential for immunotherapy for this population has not been evaluated. Recent trials suggest that tumors with a genetic basis for PD-1 (programmed cell death protein 1) ligand expression are highly sensitive to therapeutic antibodies targeting PD-1. OBJECTIVE To determine the genetic status of CD274 (encoding PD-L1 [programmed cell death 1 ligand 1]) and PDCD1LG2 (encoding PD-L2 [programmed cell death 1 ligand 2]) in SCCs of the cervix and vulva and to correlate the findings with PD-L1 protein expression. DESIGN, SETTING, AND PARTICIPANTS We performed fluorescence in situ hybridization (FISH) using probes targeting CD274, PDCD1LG2, and the centromeric portion of chromosome 9, and immunohistochemistry (IHC) using an antibody recognizing PD-L1 on formalin-fixed, paraffin-embedded (FFPE) biopsy specimens from 48 cervical SCCs and 23 vulvar SCCs. MAIN OUTCOMES AND MEASURES Tumors were categorized according to the genetic abnormality in CD274 and PDCD1LG2 (coamplification > cogain > polysomy > disomy) as detected by FISH, and evaluated on a semiquantitative scale (modified H score, the product of the percentage of tumor cells with positive staining and the maximum intensity of positive staining) for PD-L1 protein expression as detected by IHC. RESULTS Overall, 71 samples of FFPE tissue from cases of cervical SCCs (n = 48) and vulvar SCCs (n = 23) were retrieved from the archives of Brigham and Womens Hospital and included in this study. We observed cogain or coamplification of CD274 and PDCD1LG2 in 32 of 48 cervical SCCs (67%) and 10 of 23 vulvar SCCs (43%). Median PD-L1 protein expression was highest among tumors with CD274 and PDCD1LG2 coamplification and lowest among tumors with disomy. CONCLUSIONS AND RELEVANCE Recurrent copy number gain of the genes encoding the PD-1 ligands provides a genetic basis for PD-L1 expression in a subset of cervical and vulvar SCCs and identifies a class of patients that are rational candidates for therapies targeting PD-1.

Complications of pelvic radiation in patients treated for gynecologic malignancies.

Radiation therapy is a critical treatment modality in the management of patients with gynecologic tumors. New highly conformal external‐beam and brachytherapy techniques have led to important reductions in recurrence and patient morbidity and mortality. However, patients who receive pelvic radiation for gynecologic malignancies may experience a unique constellation of toxicity because of the anatomic locations, combination with concurrent chemotherapy and/or surgery, as well as potential surgical interventions. Although side effects are often categorized into acute versus late toxicities, several late toxicities represent continuation and evolution of the same pathologic process. Comorbidities and radiation dose can significantly increase the risk of morbidity. Current understanding of the incidence of various morbidities in patients treated with current radiation techniques for gynecologic malignancies, the impact of chemotherapy and surgery, treatment options for those effects, and future areas of research are highlighted. Cancer 2014;120:3870–3883.

Vaginal brachytherapy for early stage uterine papillary serous and clear cell endometrial cancer

OBJECTIVE To report clinical outcomes following adjuvant high-dose-rate (HDR) vaginal brachytherapy (VB) for early-stage uterine papillary serous (UPSC) and clear cell (CC) endometrial cancer. METHODS A retrospective study of Stage I and II papillary serous and clear cell endometrial cancer treated with post-operative HDR VB between October 2005 and May 2012 was performed. A total of 37 patients were identified, 26 with UPSC, 9 with CC and 2 with mixed UPSC/CC. After total hysterectomy and bilateral salpingo-oophorectomy, VB was administered without external-beam radiation with a dose of 24 Gy in 6 fractions prescribed to the vaginal surface. Chemotherapy was given to 30 patients (75%). RESULTS The median follow up time was 24.8 months (range, 2.0 to 71.5 months). Four patients relapsed, 2 with UPSC and 2 with CC. The initial site of relapse was concurrent vagina, pelvic/para-aortic nodes and abdominal wall (1), pelvic/para-aortic nodes (1) and para-aortic nodes alone (2). The 2-year vaginal-control rate was 96.8%. The pelvic-control rate including vaginal and nodal relapse was 93.5%. The 2-year disease-free and overall survival rates were 89.3% and 100%, respectively. CONCLUSION HDR VB as the sole adjuvant treatment modality for early-stage UPSC/CC is associated with a low rate of vaginal relapse and excellent survival outcomes. This novel low-dose regimen for VB is safe and effective.