Abstract PD5-2: Preclinical assessment of HDAC inhibitor entinostat combined with all trans retinoic acid (ATRA) in aromatase inhibitor resistant breast cancer

Treatment with aromatase inhibitors (AI’s) is highly effective against breast cancer in ER positive postmenopausal women. However, some patients eventually become resistant to AIs. Tumor initiating cells (TIC’s) represent a subpopulation of tumor cells, which show self-renewal capacity. We are focused towards discovering strategies to reduce the growth of breast cancer TICs, which may result in resistance. We have developed a xenograft model that mimics post-menopausal hormone responsive breast cancer. In this model, aromatase transfected human hormone sensitive MCF-7 cells (MCF-7Ca) are inoculated in ovariectomized athymic nude mice and allowed to grow in presence of D4A (aromatizable substrate of estrogen). Results obtained using this model have been confirmed by numerous clinical trials. Using this model, we have established that single agent AI is better than tamoxifen in controlling tumor growth. We also observed that although, AI letrozole provides a longer control over tumor growth, tumors eventually began to grow. In the current study, we investigated the effect of ATRA (All-trans Retinoic acid) (125μg/day, ip) and a histone deacetylase (HDAC) inhibitor entinostat (SNDX- 275) (50μg/day, po) with or without letrozole on letrozole resistant tumors in a xenograft model system. Ovariectomized athymic nude mice bearing xenografts of MCF-7Ca cells, were treated with letrozole till they became resistant (15 weeks). At this time, the mice were grouped to receive ATRA, entinostat plus ATRA or the combination of ATRA plus entinostat plus letrozole till week 23. The mice treated with entinostat plus ATRA letrozole showed a significant decrease in tumor growth rate compared to mice treated with single agents or entinostat plus ATRA (p<0.0001, p = 0.02). On week 20 weeks, 2 mice from each treatment group were euthanized and tumors were harvested. The tumors were digested enzymatically with collagenase and hyaluronidase and freed of debris using centrifugation and filtration. Mammosphere forming ability of TICs in the tumor tissue was measured by seeding 10,000 viable cells from each treated tumors under non-adherent conditions to access the self-renewal capacity. Quantitative PCR analysis of tumors cells showed a significant downregulation of the known TIC molecular markers, BCRP, ALDH, BMI-1 and Nanog compared to letrozole treated tumors. Similar results were also obtained when LTLT-Ca (long term letrozole treated MCF-7Ca) cells treated with ATRA and entinostat in combination with letrozole and then seeded in non-adherent conditions. The combination of ATRA plus ENT plus letrozole significantly (p<0.01) reduced number of mammospheres formed compared to single agents alone. We have shown previously, that LTLT-Ca cells have higher percentage of side population (cells expressing higher level of efflux pumps such as BCRP) compared to MCF-7Ca cells. The treatment of LTLT-Ca cells with the combination of ENT and ATRA with letrozole drastically reduced the percentage of side population. Overall, these studies indicate that the combination of ATRA, entinostat and letrozole is effective in reducing tumor recurrence in letrozole resistant tumors.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr PD5-2.

Abstract P1-07-01: Histone deacetylase inhibitor entinostat reverses epithelial to mesenchymal transition of breast cancer cells by reversing the repression of E-cadherin

Loss of ERa in breast cancer correlates with poor prognosis, increased recurrence rates and higher incidence of metastasis. In our previous studies, we have shown that histone deacetylase (HDAC) inhibitor entinostat (ENT) can upregulate ERα and aromatase in ER-negative cells and tumors, making them sensitive to aromatase inhibitors (AIs). In the current study, we are showing that ENT can also reverse epithelial to mesenchymal transition (EMT), which is considered to be a first step in the process of metastases formation. EMT is characterized by loss of intracellular adhesion (loss of E-cadherin); loss of epithelial markers such as cytokeratins and upregulation of mesenchymal markers such as vimentin; acquisition of fibroblast-like spindle morphology and increased motility. Various carcinomas undergo varying degrees of EMT and capacity to undergo EMT correlates inversely with levels of E-Cadherin. It is widely accepted that loss of E-cadherin is associated with more invasive phenotype. Epigenetic silencing of E-cadherin has been implicated in metastatic cell lines and invasive breast cancers.

Triple negative breast cancer cells such as MDA-MB-231 and Hs578T show a basal phenotype characterized by loss of E-cadherin expression and higher expression of mesenchymal markers such as N-cadherin, vimentin along with transcriptional repressors such as twist and snail.

In this study, we measured the effect of entinostat on the EMT. When MDA-MB-231 and Hs578T cells were treated with ENT, E-cadherin transcription was increased along with reduction in N-cadherin mRNA expression. Similar results were also seen in tumors of MDA-MB-231 and Hs578T xenografts treated with ENT (for 5 weeks and 2 weeks respectively). A dose dependent increase in E-cadherin was seen along with a dose dependent decrease in N-cadherin mRNA. Although, we did not observe any reduction in vimentin protein, phosphorylation of vimentin was increased and vimentin remodeling was changed as seen by immunofluorescence. We performed chromatin immunoprecipitation (ChIP) assay to measure the activation of E-cadherin promoter. Treatment of MDA-MB-231 and Hs578T cells increased the activation of E-cadherin promoter as seen by increased acetyl histones at the promoter region of E-cadherin. Twist and snail are known repressors of E-cadherin gene and we saw that ENT treatment reduced the association of twist and snail with the E-cadherin promoter. ENT was also able to downregulate twist, which may be responsible for reduced twist association with the E-cadherin promoter.

In summary, these findings suggest that HDAC inhibitor ENT can reverse EMT and may help reduce the formation of metastasis.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-07-01.

Antidepressants for mothers: what are psychiatrists prescribing?

BACKGROUND AND AIMS

Depressive illness in the perinatal period is common and can be associated with detrimental effects to both mother and child. The evolving evidence base on the safety of antidepressants in pregnancy and breastfeeding can make prescribing decisions challenging. This study aimed to investigate current prescribing practices and attitudes of hospital psychiatrists towards depression in pregnant and breastfeeding mothers.

METHODS AND RESULTS

This qualitative survey was conducted by way of e-mail survey to 95 psychiatrists, of all grades and specialities, based within The Royal Edinburgh Hospital. A majority of psychiatrists are choosing and avoiding antidepressants in accordance with the National Institute for Health and Clinical Excellence guidelines. A minority of respondents are selecting classes of antidepressants, which raises concern about the safety of such prescribing decisions. The majority of psychiatrists expressed a lack of confidence when prescribing and expressed a wish for further training in this area.

CONCLUSION

This study indicates a degree of uncertainty amongst psychiatrists of all grades when prescribing to these special groups. We would recommend increased training in this area to all psychiatrists and an increased emphasis placed upon incorporating perinatal psychiatry within the postgraduate psychiatric curriculum.

Minimally invasive fetal therapy for hydropic lung masses: three different approaches and review of the literature

OBJECTIVE

To report three different antenatal therapeutic approaches for fetal lung masses associated with hydrops.

METHODS

Three prospectively followed cases are described, and all 30 previously published minimally invasive cases of fetal therapy for hydropic lung masses are reviewed.

RESULTS

Three hydropic fetuses with large intrathoracic lung masses presented at 17, 25 and 21 weeks of gestation, respectively. An aortic feeding vessel was identified in each case and thus a bronchopulmonary sequestration (BPS) was suspected. Under ultrasound guidance, the feeding vessel was successfully occluded with interstitial laser (Case 1), radiofrequency ablation (RFA) (Case 2) and thrombogenic coil embolization (Case 3). Complete (Cases 1 and 2) or partial (Case 3) resolution of the lung mass and hydrops was observed. A healthy infant was born at term after laser therapy (Case 1), and the involved lung lobe was resected on day 2 of postnatal life. In Case 2, hydrops resolved completely following RFA, but an iatrogenic congenital diaphragmatic hernia and abdominal wall defect became apparent 4 weeks later. The neonate died from sepsis following spontaneous preterm labor at 33 weeks. In Case 3, despite technical success in complete vascular occlusion with coils, a stillbirth ensued 2 days after embolization.

CONCLUSIONS

The prognosis of large microcystic or echogenic fetal chest masses associated with hydrops is dismal. This has prompted attempts at treatment by open fetal surgery, with mixed results, high risk of premature labor and consequences for future pregnancies. We have demonstrated the possibility of improved outcome following ultrasound-guided laser ablation of the systemic arterial supply. Despite technical success, RFA and coil embolization led to procedure-related complications and need further evaluation.

Diagnostic accuracy of diffusion tensor imaging for pediatric cervical spinal cord injury

STUDY DESIGN

Cross-sectional non-experimental study.

OBJECTIVES

To examine diagnostic accuracy of diffusion tensor imaging (DTI) for pediatric spinal cord injury (SCI).

SETTING

Pediatric Orthopedic Hospital.

METHODS

Thirty-five subjects, 10 SCI and 25 controls, mean age 13.38 years underwent two scans with 3.0 T MR scanner. Fractional anisotropy (FA), axial diffusivity (AD) and radial diffusivity (RD) values were calculated. Subjects with SCI underwent examination of muscle strength, sensation and sacral sparing. Mean and s.d. values for FA, AD and RD were compared by group (controls, SCI with sacral sparing, SCI without sacral sparing) using analysis of variance for repeated measures. Comparisons were also made of DTI values at the injury site to values from cervical regions outside of the injury site. Specificity, sensitivity, receiver operating characteristics area under the curve (ROC AUC) and corresponding 95% confidence intervals were calculated. Resampling methods were used to validate the estimates from the final models.

RESULTS

FA values differed among SCI subjects with intact sacral sparing, absent sacral sparing and controls, P<0.003 (adjusted). DTI values in combination showed the strongest diagnostic accuracy for predicting the presence of anal contraction (AD, RD; ROC AUC=0.90), deep anal pressure (FA; ROC AUC=0.88), S4-5 sensation (FA, RD; ROC AUC=0.93), motor level (FA, AD, RD; ROC AUC=0.92) and MRI level (FA, AD, RD; ROC AUC=0.92). Bootstrap and Jackknife median values indicated consistency of the parameter estimates.

CONCLUSION

The predictive accuracy of DTI for sacral sparing end points and motor and MRI level of injury was good to strong.

Peripherally inserted central catheter tip position and risk of associated complications in neonates

OBJECTIVE

To characterize the relationship between peripherally inserted central catheters (PICC) tip positions and associated complications in neonates.

STUDY DESIGN

Catheter tip position for 319 infants was classified into superior vena cava (SVC, n=131), inferior vena cava (IVC, n=72), brachiocephalic (BC, n=59), midclavicular (MC, n=49) or iliac. Duration of catheter stay and complication profile was compared between central (SVC/IVC) vs non-central PICC, and between SVC vs IVC, SVC vs BC and SVC vs MC. Kaplan-Meier survival analysis and regression models were used.

RESULT

Overall length of catheter stay was similar between central and non-central group. Non-central catheters (n=116) had higher complication rates (47 vs 29%; P=0.001), non-elective removals (45 vs 27%; P=0.002) and shorter time to complication (6.2 vs 11.4 days; P=0.043). This difference was primarily due to the complications encountered in MC group, which had the highest rate of infiltration (P<0.001) and mechanical complications while outcomes were similar among other subgroups. Interestingly, catheter survival probability was similar in all groups for first 4 days. Rate and types of blood stream infections were not related to catheter tip position.

CONCLUSION

Non-central PICCs are associated with higher rates of infiltration and mechanical complications when the tip is in MC region. BC catheters may have comparable outcomes to SVC in neonates. A careful risk-benefit analysis is warranted when MC catheters are used in neonates.

A dose-finding study of temsirolimus and liposomal doxorubicin for patients with recurrent and refractory bone and soft tissue sarcoma

There are few effective therapies for high-risk sarcomas. Initial chemosensitivity is often followed by relapse. In vitro, mammalian target of rapamycin (mTOR) inhibition potentiates the efficacy of chemotherapy on resistant sarcoma cells. Although sarcoma trials using mTOR inhibitors have been disappointing, these drugs were used as maintenance. We conducted a Phase I/II clinical trial to test the ability of temsirolimus to potentiate the cytotoxic effect of liposomal doxorubicin and present here the dose-finding portion of this study. Adult and pediatric patients with recurrent or refractory sarcomas were treated with increasing doses of liposomal doxorubicin and temsirolimus using a continual reassessment method for escalation, targeting a dose-limiting toxicity rate of 20%. Blood samples were drawn before and after the first dose of temsirolimus in Cycles 1 and 2 for pharmacokinetic analysis. The maximally tolerated dose combination was liposomal doxorubicin 30 mg/m(2) monthly with temsirolimus 20 mg/m(2) weekly. Hematologic toxicity was common but manageable. Dose-limiting toxicities were primarily renal. Concurrent administration of liposomal doxorubicin resulted in increased exposure to sirolimus, the active metabolite of temsirolimus. Thus, the combination of liposomal doxorubicin and temsirolimus is safe for heavily pretreated sarcoma patients. Co-administration with liposomal doxorubicin did not alter temsirolimus pharmacokinetics, but increased exposure to its active metabolite.

CYP3A-dependent drug metabolism is reduced in bacterial inflammation in mice

BACKGROUND AND PURPOSE

Gene expression of Cyp3a11 is reduced by activation of Toll-like receptors (TLRs) by Gram-negative or Gram-positive bacterial components, LPS or lipoteichoic acid (LTA) respectively. The primary adaptor protein in the TLR signalling pathway, TIRAP, plays differential roles in LPS- and LTA-mediated down-regulations of Cyp3a11 mRNA. Here, we have determined the functional relevance of these findings by pharmacokinetic/pharmacodynamic (PK/PD) analysis of the Cyp3a substrate midazolam in mice. Midazolam is also metabolized by Cyp2c in mice.

EXPERIMENTAL APPROACH

Adult male C57BL/6, TIRAP+/+ and TIRAP-/- mice were pretreated with saline, LPS (2 mg·kg⁻¹) or LTA (6 mg·kg⁻¹). Cyp3a11 protein expression, activity and PK/PD studies using midazolam were performed.

KEY RESULTS

Cyp3a11 protein expression in LPS- or LTA-treated mice was reduced by 95% and 60% compared with saline-treated mice. Cyp3a11 activity was reduced by 70% in LPS- or LTA-treated mice. Plasma AUC of midazolam was increased two- to threefold in LPS- and LTA-treated mice. Plasma levels of 1'-OHMDZ decreased significantly only in LTA-treated mice. Both LPS and LTA decreased AUC of 1'-OHMDZ-glucuronide. In the PD study, sleep time was increased by ∼2-fold in LPS- and LTA-treated mice. LTA-mediated decrease in Cyp3a11 protein expression and activity was dependent on TIRAP. In PK/PD correlation, AUC of midazolam was increased only in LPS-treated mice compared with saline-treated mice.

CONCLUSIONS AND IMPLICATIONS

LPS or LTA altered PK/PD of midazolam. This is the first study to demonstrate mechanistic differences in regulation of metabolite formation of a clinically relevant drug by Gram-negative or Gram-positive bacterial endotoxins.