Predicting Daily Maintenance Dose of Fluindione, an Oral Anticoagulant Drug

Due to large inter-individual variations, the dose of vitamin K antagonist required to target the desired hypocoagulability is hardly predictible for a given patient, and the time needed to reach therapeutic equilibrium may be excessively long. This work reports on a simple method for predicting the daily maintenance dose of fluindione after the third intake. In a first step, 37 patients were delivered 20 mg of fluindione once a day, at 6 p.m. for 3 consecutive days. On the morning of the 4th day an INR was performed. During the following days the dose was adjusted to target an INR between 2 and 3. There was a good correlation (r = 0.83, p<0.001) between the INR performed on the morning of day 4 and the daily maintenance dose determined later by successive approximations. This allowed us to write a decisional algorithm to predict the effective maintenance dose of fluindione from the INR performed on day 4. The usefulness and the safety of this approach was tested in a second prospective study on 46 patients receiving fluindione according to the same initial scheme. The predicted dose was compared to the effective dose soon after having reached the equilibrium, then 30 and 90 days after. To within 5 mg (one quarter of a tablet), the predicted dose was the effective dose in 98%, 86% and 81% of the patients at the 3 times respectively. The mean time needed to reach the therapeutic equilibrium was reduced from 13 days in the first study to 6 days in the second study. No hemorrhagic complication occurred. Thus the strategy formerly developed to predict the daily maintenance dose of warfarin from the prothrombin time ratio or the thrombotest performed 3 days after starting the treatment may also be applied to fluindione and the INR measurement.

Influence of Long Term Oral Anticoagulants upon Prothrombin Fragment 1 + 2, Thrombin-Antithrombin III Complex and D-Dimer Levels in Patients Affected by Proximal Deep Vein Thrombosis

We have investigated the influence of long term oral anticoagulants (OAC) upon the plasma levels of prothrombin fragment 1 + 2 (F1 + 2), of thrombin-antithrombin III complexes (TAT) and of D-Dimer in 20 patients affected by a proximal deep vein thrombosis (DVT) diagnosed by ultrasonic duplex scanning. Patients (63 ± 17 years, mean ± SD) were sampled at the beginning of the OAC treatment (day 1), which was started 1 to 6 days after diagnosis confirmation and full heparinization, and then 8, 35 and 92 days after. The results were compared to those obtained in a blood donor population (39 ± 10 years) and to an age-matched healthy population (63 ± 19 years). The mean INR determined on days 8, 35 and 92 were almost identical (2.8 ± 0.7, 2.9 ± 0.9 and 2.8 ± 0.6 respectively). In contrast, highly significant variations of the three markers were recorded during the observation period. Eight days after the beginning of OAC, increased levels of TAT complexes were associated with subnormal levels of F1 + 2 suggesting persistence of a hypercoagulable state. On the further sampling times, TAT complexes were in the normal range while F1 + 2 were far below the normal range. Between day 1 and day 92, the levels of D-Dimer continuously decreased reflecting a long-term fibrinolytic process.

This study clearly indicates that high INR are not systematically associated with very low F1 + 2 levels, particularly in the acute phase of thrombosis. Whether or not it is possible to reduce the intensity of the anticoagulant treatment 1 month after its initiation on the basis of very low levels of F1 + 2 can only be determined by prospective clinical trials.

Abstract P4-09-09: Correlation of breast cancer index (BCI) predictive (HoxB13/IL17BR) results to nodal status and hormone receptor expression in early stage HR+ breast cancer

Background: The HoxB13/IL17BR (H/I) ratio, the endocrine response component of the Breast Cancer Index (BCI), was initially discovered in patients with LN- breast cancer, and validated as a predictive biomarker of benefit from extended endocrine therapy (EET) in a cohort from MA.17 that included both LN- and LN+ patients. Here, correlative analyses were performed to further characterize BCI Predictive (H/I) results with nodal status and quantitative hormone receptor expression.

Methods: Analyses were performed using data from the BCI Clinical Database for Correlative Studies, an IRB-approved de-identified database that contains &gt;50 clinicopathologic and molecular variables from cases submitted for BCI in clinical practice (N=19,126). Clinicopathologic variables were abstracted from pathology reports, and were available for a subset of these cases. Cases from patients with confirmed nodal status were analyzed. Chi-squared tests and ANOVA were used to compare results between subgroups.

Results: Analyses included 13,114 patients (median age 58.9y; range 23-92y); 9562 were LN- and 3552 LN+. The distribution of individual H/I scores and proportion of patients classified as High H/I were generally similar in LN- and LN+ patients, though a modestly greater proportion of LN+ patients (46.2%) were classified as High H/I compared to LN- patients (42.0%; P&lt;0.01). In both LN- and LN+ patients, median quantitative ER (qER) expression was slightly higher in patients with Low H/I than with High H/I; qPR showed the same trend but with a larger magnitude (P&lt;0.0001 for both). Similar results were observed for percent positive staining by IHC (P&lt;0.0001). In both LN- and LN+ patients, H/I showed a weak negative correlation with qER (LN-, 0.227; LN+, 0.192) and qPR expression (LN-, 0.311; LN+, 0.311).

Conclusion: In this study to evaluate potential biological correlates of BCI, results showed that H/I biomarker activity did not appear to be dependent on nodal status. Secondly, although ER expression is an established biomarker for endocrine sensitivity, High H/I status did not correlate with increased quantitative ER and PR expression. The H/I ratio may be an independent new marker for endocrine sensitivity independent of the strength of ER expression.

Citation Format: Elias A, Israel MA, Zhang Y, Schnabel CA, Mayordomo J. Correlation of breast cancer index (BCI) predictive (HoxB13/IL17BR) results to nodal status and hormone receptor expression in early stage HR+ breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-09-09.

Abstract P1-07-12: Correlation of breast cancer index (BCI) prognostic and predictive results to clinicopathologic risk groups in early stage HR+ breast cancer

Background: Both clinicopathologic factors and genomic tests have been shown to be prognostic for risk of late distant recurrence (DR); however, few studies have characterized differential patient stratification.Breast Cancer Index (BCI) is a validated gene expression assay for patients with early-stage HR+ breast cancer that provides a prognostic result for high vs low risk of late distant recurrence and a separate predictive result (based on the HoxB13/IL17BR [H/I] ratio) for high vs low likelihood of benefit from extended endocrine therapy. Thus four categories of results are possible based on a patient's tumor biology. To better understand how patient stratification is affected by a combination of clinicopathologic and genomic factors, this study examined BCI assay results within clinicopathologic risk categories based on tumor size and grade.

Methods: This study utilized data from the BCI Clinical Database for Correlative Studies, an IRB-approved de-identified database which contains clinicopathologic and molecular variables from 19,126 clinical cases submitted for BCI testing. Clinicopathologic variables, abstracted from pathology reports, were available for a subset of these cases. This analysis evaluated cases from LN- patients with available clinicopathologic data. Chi-squared tests were used to compare BCI results between tumor size and grade subgroups.

Results: Analyses included 3843 LN- patients (median age 59.1y; range 26-89y; 74% ≥50y), of which 31%, 52%, 17% were Grade 1, 2, and 3, respectively, and 5%, 22.7%, 48.9%, 21.7%, and 1.6% were T1mi/a, T1b, T1c, T2, and T3, respectively. In analysis based on tumor size, there was a wide distribution of individual BCI Prognostic scores in all tumor size subsets; however, the proportion of patients classified as high risk increased with larger tumor size (T1a/b 39.0%, T1c 50.1%, T2 61.0%; p&lt;.0001). In contrast, BCI Predictive (H/I) was not as strongly correlated with size, with a modestly larger proportion of patients classified as High H/I with larger tumor size (T1a/b 37.2%, T1c 40.5%, and T2 45.3%; p=.005). Within each tumor size category, the proportion of patients classified as BCI High Risk and High H/I increased with tumor grade (p&lt;.0001). However, there was a wide distribution of individual risk assessments by BCI Prognostic and stratification by BCI Predictive (H/I) in all size + grade subsets. In patients with the most favorable clinicopathologic risk profile (T1a/b, G1), BCI classified 20% as high risk, 68% of whom also had High H/I.

Conclusion: While BCI results correlated with tumor size and grade, BCI identified substantial proportions of patients with favorable clinicopathologic features as high risk for late DR and apparent high likelihood of benefit from EET; conversely, BCI also identified patients with high risk clinicopathologic features as low risk for late distant recurrence and apparent low likelihood of benefit from EET. These findings help to differentiate between genomic-based and clinicopathologic-based risk/benefit assessment for patients considering EET.

Citation Format: Mayordomo J, Falkson C, Kepes J, Israel MA, Schroeder BE, Schnabel CA, Elias A. Correlation of breast cancer index (BCI) prognostic and predictive results to clinicopathologic risk groups in early stage HR+ breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-07-12.

Prevalence of and factors associated with burnout among health care professionals in Arab countries: a systematic review

BACKGROUND

Burnout among healthcare professionals is one of the key challenges affecting health care practice and quality of care. This systematic review aims to (1) estimate the prevalence of burnout among health care professionals (HCP) in Arab countries; and (2) explore individual and work-related factors associated with burnout in this population.

METHODS

Multiple electronic databases were searched for studies published in English or Arabic from January 1980 to November 2014 assessing burnout (using the Maslach Burnout Inventory; MBI) amongst health care professionals (HCP) in Arab countries.

RESULTS

Nineteen studies (N = 4108; 49.3% females) conducted on HCP in Bahrain, Egypt, Jordan, Lebanon, Palestine, Saudi Arabia and Yemen were included in this review. There was a wide range of prevalence estimates for the three MBI subscales, high Emotional Exhaustion (20.0-81.0%), high Depersonalization (9.2-80.0%), and low Personal Accomplishment (13.3-85.8%). Gender, nationality, service duration, working hours, and shift patterns were all significantly associated with burnout.

CONCLUSIONS

Within the constraints of the study and the range of quality papers available, our review revealed moderate-to-high estimates of self-reported burnout among HCP in Arab countries that are similar to prevalence estimates in non-Arabic speaking westernized developed countries. In order to develop culturally appropriate interventions, further research using longitudinal designs is needed to confirm the risk factors for burnout in specific HCP settings and specialties in Arab countries.

Psychometric Properties of the Malay Language Version of Knee Injury and Osteoarthritis Outcome Score (KOOS) Questionnaire among Knee Osteoarthritis Patients: A Confirmatory Factor Analysis

Introduction: This study aimed to cross-culturally adapt a Malay version of Knee Injury and Osteoarthritis Outcome Score (KOOS) and to evaluate its psychometric properties in patients with knee osteoarthritis (OA).

Materials and Methods: The English version KOOS was translated into a Malay version using forward and backward translation process, followed by face validity and content validity. Two hundred and twenty-six knee OA patients attending the Outpatient and Orthopaedic Clinics, Universiti Sains Malaysia Hospital, completed the Malay version KOOS. Construct validity using confirmatory factor analysis and internal reliability assessment were performed.

Results: The results showed that the original five-factor model with 42 items failed to achieve acceptable values of the goodness of fit indices, indicating poor model fit. A new five-factor model of 26 items demonstrated acceptable level of goodness of fit (comparative fit index= 0.929, incremental fit index= 0.930, Tucker Lewis fit index= 0.920, root mean square error of approximation= 0.073 and Chisquared/degree of freedom= 2.183) indices to signify a model fit. The Cronbach’s alpha value for the new model ranged from 0.776 to 0.946. The composite reliability values of each construct ranged between 0.819 and 0.921, indicating satisfactory to high level of convergent validity.

Conclusion: The five-factor model with 26 items in the Malay version of KOOS questionnaire demonstrated a good degree of goodness of fit and was found to be valid, reliable and simple as an assessment tool for symptoms, pain, activity of daily living, sports and recreational activity and quality of life for Malaysian adults suffering from knee osteoarthritis.

Site promiscuity of coliphage HK022 integrase as a tool for gene therapy

The integrase (Int) encoded by the lambdoid coliphage HK022 targets in its host chromosome a 21 base pair (bp) recombination site termed attB or BOB'. attB comprises two 7 bp partially inverted (palindromic) Int-binding sites of 7 bp each termed B and B'. B and B' flank a central 7 bp crossover site or 'overlap' (O). We show that replacing O with a random 7 bp sequence supports Int-mediated site-specific recombination as long as the cognate and larger phage recombination site attP features an identical O sequence. This promiscuity allowed us to identify on the human genome several native active secondary attB sites ('attB') with random overlaps that flank human deleterious mutations, raising the prospect of using such sites to cure the 'attB'-flanked mutations by Int-catalyzed RMCE (recombinase-mediated cassette exchange) reactions. An analysis of such active and inactive 'attB's suggested a minimal 14-15 bp attB consensus sequence (instead of the 21 bp) with a reduced 3 bp palindrome.

A hybrid biological process of indoor air treatment for toluene removal

Bioprocesses, such as biofiltration, are commonly used to treat industrial effluents containing volatile organic compounds (VOCs) at low concentrations. Nevertheless, the use of biofiltration for indoor air pollution (IAP) treatment requires adjustments depending on specific indoor environments. Therefore, this study focuses on the convenience of a hybrid biological process for IAP treatment. A biofiltration reactor using a green waste compost was combined with an adsorption column filled with activated carbon (AC). This system treated a toluene-micropolluted effluent (concentration between 17 and 52 μg/m3), exhibiting concentration peaks close to 733 μg/m3 for a few hours per day. High removal efficiency was obtained despite changes in toluene inlet load (from 4.2 x 10(-3) to 0.20 g/m3/hr), which proves the hybrid system's effectiveness. In fact, during unexpected concentration changes, the efficiency of the biofilter is greatly decreased, but the adsorption column maintains the high efficiency of the entire process (removal efficiency [RE] close to 100%). Moreover, the adsorption column after biofiltration is able to deal with the problem of the emission of particles and/or microorganisms from the biofilter. Implications: Indoor air pollution is nowadays recognized as major environmental and health issue. This original study investigates the performance of a hybrid biological process combining a biofilter and an adsorption column for removal of indoor VOCs, specifically toluene.

Accelerated ageing of an EAF black slag by carbonation and percolation for long-term behaviour assessment

The efficient reuse of industrial by-products, such as the electric arc furnace (EAF) black slag, is still hindered by concern over their long-term behaviour in outdoor environments. The aim of this study was to develop an accelerated ageing method to simulate the long-term natural carbonation of EAF slag exposed to the elements. The degree of carbonation achieved in a freshly produced slag after accelerated ageing and in a slag used on a fifteen-year-old unpaved road was very similar. The influence of particle size on accelerated carbonation was assessed, with it being concluded that the slag sample with a particle size bigger than 5-6 mm underwent slight carbonation over time when it was exposed to CO2. The accelerated ageing procedure based on percolating a previously carbonated water solution through the slag column allowed gradual leaching with simulated acid rain, as well as providing information about the gradual and total chemical release from the slag. Three classification groups were established according to the release rate of the determined elements. The joint use of the accelerated carbonation method and the percolation test is proposed as a useful tool for environmental risk assessment concerning the long-term air exposure of EAF black slag.

Abstract P4-12-09: Results from a phase 2a study of trastuzumab emtansine, paclitaxel, and pertuzumab in patients with HER2-positive metastatic breast cancer

Introduction

The antibody-drug conjugate trastuzumab emtansine (T-DM1) combines the antitumor properties of trastuzumab (H) with the cytotoxic agent DM1 via a stable linker. T-DM1 prolonged PFS and OS vs standard therapy in a phase 3 study of patients (pts) with HER2-positive metastatic breast cancer (MBC) previously treated with H and a taxane. Preclinical data suggest synergy when T-DM1 is combined with paclitaxel (T) or pertuzumab (P). In the phase 1b study TDM4652g, the maximum tolerated doses of T-DM1 + T ± P were defined. Here we present results from the phase 2a expansion, which further explored feasibility and safety.

Methods

TDM4652g is a phase 1b/2a open-label study of pts with HER2-positive locally advanced or MBC. Pts had no prior T-DM1 or P, no baseline peripheral neuropathy (PN; phase 2a only), and had LVEF ≥50%. Pts in phase 2a were randomized to T-DM1 3.6 mg/kg q3w + T 80 mg/m2 qw ± P 840 mg loading dose [LD], then 420 mg q3w. The primary objective, feasibility, was assessed by the percent of evaluable pts receiving ≥12 doses of T within 15 weeks of cycle 1, day 1, and those receiving 12 consecutive weeks of T.

Results

Forty-four pts were enrolled (T-DM1 + T, n = 22; T-DM1 + T + P, n = 22); the data snapshot date was May 23, 2013. Median age was 52.5 years (range, 35–81); median number of prior agents for MBC was 6 (range, 0–12). 43 (98%) pts had previously received H, and 36 (82%) pts had received taxane therapy. Median dose intensities were T-DM1, 94% (range 54–105); T, 50% (range 9–100) and P, 100% (range 67–100). 2 pts were not evaluable for feasibility (progressive disease [PD] before receiving 12 doses of T). 21/42 (50%) pts received ≥12 doses of T within 15 weeks; 6/42 (14%) pts received 12 consecutive doses by week 12, and 33/42 (79%) pts received ≥8 doses within 12 weeks. Grade 3/4 adverse events (AEs) were reported for 18 (82%) and 17 (77%) pts in the T-DM1 + T and T-DM1 + T + P groups, respectively (see Table for AEs and best responses). Ten pts discontinued early due to PD (n = 6), PD-related death (n = 2), AEs (n = 1), or withdrawal from the study (n = 1). 21 pts discontinued T due to AEs, most commonly PN (n = 12).

Grade 3/4 AEs occurring in &gt;1 patientAE, n (%)All patients (N = 44)TDM1 3.6 mg/kg q3w + T 80 mg/m2 qw (n = 22)TDM1 3.6 mg/kg q3w + T 80 mg/m2 qw + P 840 mg LD, 420 mg q3w (n = 22)Neutropenia10 (23)6 (27)4 (18)Peripheral neuropathy9 (20)3 (14)6 (27)Fatigue6 (14)3 (14)3 (14)Thrombocytopenia6 (14)5 (23)1 (5)Anemia3 (7)2 (9)1 (5)Abdominal pain2 (5)2 (9)0Decreased hemoglobin2 (5)1 (5)1 (5)Muscosal inflammation2 (5)1 (5)1 (5)Muscular weakness2 (5)02 (9)Nausea2 (5)1 (5)1 (5)Best response,* n (%)CR2 (5)1 (5)1 (5)CR confirmed1 (2)1 (5)0PR27 (61)13 (59)14 (64)PR confirmed8 (18)3 (14)5 (23)SD10 (23)6 (27)4 (18)PD3 (7)1 (5)2 (9)*At any time point with responses ordered CR&gt;PR&gt;SD&gt;PD.

Conclusions

Overall, 50% of pts received ≥12 doses of T within 15 weeks. Adding P to the combination of T-DM1 + T did not appear to increase the incidence of grade 3/4 AEs. Data support further investigation of T-DM1 + T ± P in larger studies in early breast cancer. Final data from all phase 2a patients will be available for the full report.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-12-09.

ABI1 and PP2CA phosphatases are negative regulators of Snf1-related protein kinase1 signaling in Arabidopsis

Plant survival under environmental stress requires the integration of multiple signaling pathways into a coordinated response, but the molecular mechanisms underlying this integration are poorly understood. Stress-derived energy deprivation activates the Snf1-related protein kinases1 (SnRK1s), triggering a vast transcriptional and metabolic reprogramming that restores homeostasis and promotes tolerance to adverse conditions. Here, we show that two clade A type 2C protein phosphatases (PP2Cs), established repressors of the abscisic acid (ABA) hormonal pathway, interact with the SnRK1 catalytic subunit causing its dephosphorylation and inactivation. Accordingly, SnRK1 repression is abrogated in double and quadruple pp2c knockout mutants, provoking, similarly to SnRK1 overexpression, sugar hypersensitivity during early seedling development. Reporter gene assays and SnRK1 target gene expression analyses further demonstrate that PP2C inhibition by ABA results in SnRK1 activation, promoting SnRK1 signaling during stress and once the energy deficit subsides. Consistent with this, SnRK1 and ABA induce largely overlapping transcriptional responses. Hence, the PP2C hub allows the coordinated activation of ABA and energy signaling, strengthening the stress response through the cooperation of two key and complementary pathways.

Monocyte-macrophage membrane possesses free radicals scavenging activity: stimulation by polyphenols or by paraoxonase 1 (PON1)

In the current study, we analysed free radicals scavenging activity of monocytes-macrophages in the absence or presence of antioxidants such as polyphenols or paraoxonase 1 (PON1). THP-1 human monocytic cell line, murine J774A.1 macrophages, as well as human primary monocytes have the capability to scavenge free radicals, as measured by the 1-diphenyl-2-picryl-hydrazyl (DPPH) assay. This effect (which could be attributed to the cell's membrane) was cell number and incubation time dependent. Upon incubation of J774A.1 macrophages with acetylated LDL (Ac-LDL), with VLDL, or with the radical generator, AAPH, the cells' lipid peroxides content, and paraoxonase 2 (PON2) activity were significantly increased. While non-treated cells decreased DPPH absorbance by 65%, the Ac-LDL-, VLDL- or AAPH-treated cells, decreased it by only 33%, 30%, or 45%, respectively. We next analysed the effect of J774A.1 macrophage enrichment with antioxidants, such as polyphenols or PON1 on the cells' free radicals scavenging activity. Non-treated cells decreased DPPH absorbance by 50%, whereas vitamin E-, punicalagin- or PJ-treated cells significantly further decreased it, by 75%. Similarly, in PON1-treated cells DPPH absorbance was further decreased by 63%, in association with 23% increment in PON1 catalytic activity. In cells under oxidative stress [treated with AAPH-, or with oxidized LDL], PON1 activity was decreased by 31% or 40%, as compared to the activity observed in PON1 incubated with non-treated cells. We conclude that monocytes-macrophages possess free radicals scavenging activity, which is decreased under atherogenic conditions, and increased upon cell enrichment with potent antioxidants such as nutritional polyphenols, or PON1.

miRNAs mediate SnRK1-dependent energy signaling in Arabidopsis

The SnRK1 protein kinase, the plant ortholog of mammalian AMPK and yeast Snf1, is activated by the energy depletion caused by adverse environmental conditions. Upon activation, SnRK1 triggers extensive transcriptional changes to restore homeostasis and promote stress tolerance and survival partly through the inhibition of anabolism and the activation of catabolism. Despite the identification of a few bZIP transcription factors as downstream effectors, the mechanisms underlying gene regulation, and in particular gene repression by SnRK1, remain mostly unknown. microRNAs (miRNAs) are 20-24 nt RNAs that regulate gene expression post-transcriptionally by driving the cleavage and/or translation attenuation of complementary mRNA targets. In addition to their role in plant development, mounting evidence implicates miRNAs in the response to environmental stress. Given the involvement of miRNAs in stress responses and the fact that some of the SnRK1-regulated genes are miRNA targets, we postulated that miRNAs drive part of the transcriptional reprogramming triggered by SnRK1. By comparing the transcriptional response to energy deprivation between WT and dcl1-9, a mutant deficient in miRNA biogenesis, we identified 831 starvation genes misregulated in the dcl1-9 mutant, out of which 155 are validated or predicted miRNA targets. Functional clustering analysis revealed that the main cellular processes potentially co-regulated by SnRK1 and miRNAs are translation and organelle function and uncover TCP transcription factors as one of the most highly enriched functional clusters. TCP repression during energy deprivation was impaired in miR319 knockdown (MIM319) plants, demonstrating the involvement of miR319 in the stress-dependent regulation of TCPs. Altogether, our data indicates that miRNAs are components of the SnRK1 signaling cascade contributing to the regulation of specific mRNA targets and possibly tuning down particular cellular processes during the stress response.

Abstract P6-05-10: Progestins exert divergent growth effects and regulate tumor-unique gene cohorts in patient derived breast cancer xenografts

Background: Progesterone is an important hormone for development and normal function of the breast; however, its role in established breast cancers is less clear. Progestins have been implicated in regulating tumor cell growth, signaling, differentiation state, and stem/progenitor properties in breast cancer cells. High dose progestin treatment can be an effective therapy for some advanced breast tumors, through an unknown mechanism. Progesterone receptors (PRs) are considered positive prognostic indicators, although their levels vary considerably among luminal subtype breast tumors. Progestin/PR regulated genes in tumor cells have only been determined in cultured breast cancer cells and mouse mammary tumor models. Here we define tumor unique progestin-dependent growth effects and gene regulation profiles in patient-derived luminal breast tumor xenografts.

Methods: For these studies, three luminal estrogen receptor (ER)+PR+ transplantable xenografts were used that were derived from one pleural effusion and two previously untreated primary tumors. All three tumors were estrogen dependent to various degrees and contained variable levels of ER (5–90%) and PR (5–90%). Tumors were grown in vivo under continuous placebo, estrogen, or estrogen plus progestin conditions for 8–10 weeks and growth parameters monitored. Gene expression profiles were determined from dissected tumors using Affymetrix® GeneChip human gene 1.1 ST microarrays and results analyzed using Partek Genomics Suite software. Specific gene regulation was confirmed by q-RT-PCR and immunohistochemistry.

Results: Progestins had an inhibitory, neutral, and stimulatory effect on estrogen dependent growth in each of the three tumor lines. Accordingly, there was relatively little overlap in PR regulated genes between the three tumors. In the tumor in which progestin treatment had a potent anti-tumor effect, progestins were strong repressors of estrogen/ER-regulated genes. Gene expression patterns between the natural hormone progesterone and the synthetic drug MPA were compared in one tumor line and found to be mostly similar. The percent of PR+ tumor cells may have influenced the potency of gene regulation. Unique progestin regulated genes were discovered in this human tumor model system that were involved in immune response, cytokine signaling, and stem/progenitor cell features.

Conclusions: Women with breast cancer are exposed to progestins naturally or through hormonal therapies and these may have a profound effect on tumor biology. In some tumors, progestins are potently anti-proliferative, while in others they elicit the opposite effect and potentiate estrogen induced tumor growth. The diversity of progestin-regulated genes in each tumor underscores the hormone's context dependent effects. Determining progestin dependent gene signatures in patient tumors may pinpoint appropriate candidates for progestin therapy in advanced tumors and/or provide a prognostic tool for predicting tumor progression.

Funded by: NIH R01 CA140985 (C.A.S.), the Grohne Fund (P.K.), and the University of Colorado Cancer Center (C.A.S., P.K.)

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-05-10.