Cardiotoxicity Associated with Nicotinamide Phosphoribosyltransferase Inhibitors in Rodents and in Rat and Human-Derived Cells Lines

Nicotinamide phosphoribosyltransferase (NAMPT) is a pleiotropic protein that functions as an enzyme, cytokine, growth factor and hormone. As a target for oncology, NAMPT is particularly attractive, because it catalyzes the rate-limiting step in the salvage pathway to generate nicotinamide adenine dinucleotide (NAD), a universal energy- and signal-carrying molecule involved in cellular energy metabolism and many homeostatic functions. Inhibition of NAMPT generally results in NAD depletion, followed by ATP reduction and loss of cell viability. Herein, we describe NAMPT inhibitor (NAMPTi)-induced cardiac toxicity in rodents following short-term administration (2-7 days) of NAMPTi's. The cardiac toxicity was interpreted as a functional effect leading to congestive heart failure, characterized by sudden death, thoracic and abdominal effusion, and myocardial degeneration. Based on exposures in the initial in vivo safety rodent studies and cardiotoxicity observed, we conducted studies in rat and human in vitro cardiomyocyte cell systems. Based on those results, combined with human cell line potency data, we demonstrated the toxicity is both on-target and likely human relevant. This toxicity was mitigated in vitro by co-administration of nicotinic acid (NA), which can enable NAD production through the NAMPT-independent pathway; however, this resulted in only partial mitigation in in vivo studies. This work also highlights the usefulness and predictivity of in vitro cardiomyocyte assays using human cells to rank-order compounds against potency in cell-based pharmacology assays. Lastly, this work strengthens the correlation between cardiomyocyte cell viability and functionality, suggesting that these assays together may enable early assessment of cardiotoxicity in vitro prior to conduct of in vivo studies and potentially reduce subsequent attrition due to cardiotoxicity.

Abstract P2-08-01: Results from a randomized placebo-controlled phase 2 trial evaluating exemestane ± enzalutamide in patients with hormone receptor–positive breast cancer

This abstract was withdrawn by the authors.

Abstract P5-08-28: Incidence of germline BRCA1- and BRCA2-mutated breast cancer in the US

Background: Breast cancer is the most common cancer and second leading cause of cancer death among women in the United States (US).1 Inherited mutations in germline breast cancer susceptibility gene 1 and 2 (gBRCAm) are associated with increased risk of developing cancers, including breast cancer.2 No published reports of gBRCAm incidence within an unselected US breast cancer population are available based on a comprehensive literature review (CLR). The main objective of this analysis is to estimate the incidence of gBRCAm breast cancer in the US.

Methods: For this analysis the Surveillance, Epidemiology, and End Results (SEER) Program 18 registries captured incidence of breast cancer by stage, age and gender.3 The size of the US population was based on United Nation's population projections and standardized to the 2010 population.4 Age-specific gBRCAm distribution and gBRCAm-specific hormonal subtype for estrogen-receptor and progesterone-receptor (ER/PR), and human epidermal growth factor receptor-2 (HER2) estimates were determined from a CLR.5-8 Tumor cells negative for ER/PR and HER2 are referred to as triple-negative breast cancer (TNBC).

Results: In 2016, it is projected that approximately 250,000 individuals will be diagnosed with invasive breast cancer (all genders). Median age range of the population with invasive breast cancer is 65-69 years and 99% are females. Majority (72%) of female invasive breast cancer cases are ER/PR+ whereas 11% of cases are TNBC. Corroborating with current publications, gBRCAm is estimated at 5% for individuals less than 50 years old and 1% among all ages. Median age range of the gBRCAm cohort is 40-44 years. After applying currently available gBRCAm specific literature parameters, the majority (55%) of gBRCAm diagnoses are TNBC.

Conclusion: In the US, patients with gBRCAm represent a small proportion (1%) of all breast cancer tissues evaluated. Majority of gBRCAm patients are diagnosed with TNBC (55%) and are younger (median age range 40-44 years) than overall breast cancer population. Age differences noticed in gBRCAm may have been due to disparity in genetic screening practices among breast cancer population in the US rather than a reflection of gBRCAm expressions. These estimates of gBRCAm incidence are driven by limited reports on an unselected population of breast cancer gBRCAm cohort; therefore sensitivity analysis is required to assess the robustness of these estimates.

1. American Cancer Society. Facts and Figures 2016.

2. Miki Y et al. Science. 1994;266:66-71.

3. Surveillance, Epidemiology, and End Results (SEER) Program (www.seer.cancer.gov) Research Data (1973-2013), National Cancer Institute, DCCPS, Surveillance Research Program, Surveillance Systems Branch, released April 2016, based on the November 2015 submission.

4. United Nations Population Division. World Population Prospects, the 2015 Revision. http://esa.un.org/unpd/wpp/.

5. van den Broek et al. Eur J Hum Genet. 2015;23:588-95.

6.Turkovic L et al. BMC Cancer. 2010;10:466.

7. Atchley DP et al. J Clin Oncol. 2008;26:4282-4321.

8. Spurdle AB et al. Breast Cancer Res. 2014;16:3419.

Citation Format: Kim R, Peterson A, Isherwood A, Uppal H, Barlev A. Incidence of germline BRCA1- and BRCA2-mutated breast cancer in the US [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 P5-08-28.

Abstract P5-06-01: Talazoparib antitumor effects in BRCA-deficient breast cancer models

Background: BRCA1 and BRCA2 functions are essential for the DNA double-strand break repair process in living cells with DNA damages. Therefore, germline pathogenic mutations in BRCA1/2 increases the risk of developing cancer.1, 2Poly(ADP-ribose) polymerase (PARP) enzymes are proteins responsible for DNA single-strand break repair. Persistent inhibition of PARP-dependent DNA repair in BRCA-deficient breast cancer cells leads to increased DNA damages resulting in cancer cell death. Talazoparib is a novel and potent, orally bioavailable, small molecule PARP inhibitor. Talazoparib's dual mechanism of action inhibits PARP enzyme activity and effectively traps PARP on DNA, preventing DNA repair, resulting in cell death in BRCA1/2-mutated cells.3 In tissue culture studies, talazoparib is more potent at trapping PARP on DNA to induce cancer cell death compared to other PARP inhibitors.4 Previous studies have demonstrated talazoparib inhibited growth in tumors harboring BRCA1/2 gene mutations. In the MX-1 breast cancer model with BRCA1-deficiency, talazoparib inhibited cell growth in vitro and induced regression in solid mouse xenografts.5 Here, we demonstrate antitumor effects of talazoparib monotherapy in a panel of breast cancer cells and patient-derived breast cancer models with pathologic BRCA1/2 mutations.

Method: A panel of human breast cancer cell lines was treated with talazoparib to determine its cytotoxic effects. BRCA1/2 mutations status was correlated to talazoparib cytotoxic effects. At the molecular level, BRCA1/2-mutant and wild type breast cancer cell lines were treated with dose-escalating talazoparib to also assess the relationship between PARP-DNA trapping complex formation and treatment response. Patient-derived breast cancer xenograft models were used to assess talazoparib monotherapy on tumorigenesis. Immunohistochemistry assays were performed to determine Ki-67, gH2AX and caspase 3 marker expression following talazoparib treatment.

Results: Cytotoxicity was observed in 50% (7/14) cell lines at IC50 values that are achieved in the clinic. BRCA1/2 alterations were detected in 21.4% (3/14) of cell lines sensitive to talazoparib treatment. In 14 patient-derived breast cancer xenograft models selected for this study, 57.1% (8/14) responded to talazoparib monotherapy. Of these, 35.7% had mutations in the BRCA1 (28.6%) and BRCA2 (7.1%) genes. Stable disease was observed in 14.2% (2/14). One stable model had BRCA1 mutations. Tumor regression was observed in 42.8% (6/14) of the models treated with talazoparib monotherapy. Importantly, 66.7% (4/6) of patient-derived breast cancer models that regressed on talazoparib monotherapy had mutations in BRCA1/2 genes.

Conclusions: Cytotoxicity was observed with talazoparib monotherapy in breast cancer cell lines and in patient-derived xenograft tumor models harboring BRCA1 or BRCA2 mutations. Our data demonstrate therapeutic potential of talazoparib monotherapy in breast cancer associated with pathologic BRCA1/2 mutations.

1.Couch FJ et al. J Clin Oncol. 2015;33:304-11.

2. Petrucelli N et al. Genet Med. 2010;12:245-59.

3. Wang B et al. J Med Chem. 2016;59:335-57.

4. Murai J et al. Mol Cancer Ther. 2014;13:433-43.

5. Shen Y et al. Clin Cancer Res. 2013;19:5003-15.

Citation Format: Phan VT, Protter AA, Peterson A, Uppal H. Talazoparib antitumor effects in BRCA-deficient breast cancer models [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 P5-06-01.

Abstract P2-07-04: A novel diagnostic androgen receptor gene signature links clinical outcomes and preclinical response to enzalutamide, paclitaxel or the combination in triple-negative breast cancer

Background: The androgen receptor (AR) is expressed in ≈70% of all breast cancers (BCs) and may be necessary for proliferation and survival advantage in AR+ tumors. A novel gene signature associated with AR-signaling biology (PREDICT AR) was developed by sequencing triple-negative BC (TNBC) tumors collected in a phase 2 study evaluating enzalutamide (ENZA) monotherapy1; clinical outcomes were superior in patients (pts) with PREDICT AR+ vs PREDICT AR- tumors.1,2 ENZA blocks nuclear localization and suppresses its activity.3 Paclitaxel (PTX) stabilizes microtubules and may also block AR nuclear localization. Thus we hypothesize that response to PTX-based therapy may be additive in PREDICT AR+ vs PREDICT AR- disease. This study sought to identify independent clinical datasets with PREDICT AR+ gene signature to assess outcomes following PTX-based therapy. Preclinically, we investigated the antitumor activity of ENZA, PTX, or ENZA+PTX in AR-driven TNBC models.

Methods: We probed publicly available TNBC clinical databases from Gene Expression Omnibus datasets to assess PREDICT AR status and clinical outcomes. Similarly, we assessed 21 TNBC lines for PREDICT AR status. BT549, MDA-MB-436, and MDA-MB-453 were treated with ENZA, PTX, or ENZA+PTX to determine activity. Cell signaling and pathway activation were assessed by western blot. ENZA and PTX activity was assessed in PREDICT AR+ xenograft models. Tumor RNA sequencing and immunohistochemistry were used to identify gene signatures, potentially predictive biomarkers, and potential synergistic effects of ENZA+PTX.

Results: The prevalence of PREDICT AR+ tumors in one cohort of 182 pts with primary TNBC4 was 51%. Distant relapse-free survival following PTX-based adjuvant/neoadjuvant therapy was not statistically different between pts with PREDICT AR+ vs PREDICT AR- TNBC (p=0.605). Pathologic complete response rates were 12.5% for PREDICT AR+ vs 21.0% for PREDICT AR- TNBC. Additional sets of pts with primary TNBC are being evaluated. Preclinically, we observed a dose-dependent inhibition of cell viability with either ENZA or PTX in AR+ TNBC cell lines and additive effects from ENZA+PTX. In PREDICT AR+ xenograft models, ENZA or PTX treatment resulted in a dose-dependent antitumor response. Combination studies are underway. Tumor RNA sequencing are being evaluated for gene signature of synergistic antitumor response to ENZA+PTX.

Conclusion: Analyzing publicly available clinical datasets, we found that PREDICT AR+ status was not associated with differential outcomes following PTX-based therapy in primary TNBC, suggesting there is potential to provide additive benefits in PTX-based therapy with ENZA. In preclinical studies, we observed additive effects when combining ENZA+PTX in PREDICT AR+ TNBC lines compared with single agent treatments. Taken together, these data suggest ENZA combined with PTX might provide additive benefits in a clinical setting for pts with PREDICT AR+ TNBC.

References

1. Traina TA et al. J Clin Oncol 2015:33(suppl):abstr 1003.

2. Parker J et al. J Clin Oncol 2015;33(suppl):abstr 1083.

3. Tran C et al. Science 2009;324:787-90.

4. Hatzis C et al. JAMA 2011;305:1873-81.

Citation Format: Phan VT, Protter AA, Peterson AC, Parker JS, Yoon K, Tudor IC, Paton V, Noonberg S, Uppal H. A novel diagnostic androgen receptor gene signature links clinical outcomes and preclinical response to enzalutamide, paclitaxel or the combination in triple-negative breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-07-04.

Risk factors for mortality in Down syndrome

BACKGROUND

Down syndrome is a genetic condition that contributes to a significantly shorter life expectancy compared with the general population. We investigated the most common comorbidities in a population of acute hospital patients with Down syndrome and further explored what the most common risk factors for mortality are within this population.

METHOD

From our database of one million patients admitted to National Health Service (NHS) Trusts in northern England, we identified 558 people who had Down syndrome. We compared this group with an age- and gender-matched control group of 5580 people.

RESULTS

The most prevalent comorbid diseases within the Down's population were hypothyroidism (22.9%) and epilepsy (20.3%). However, the conditions that had the highest relative risks (RRs) in the Down's population were septal defects and dementia. Respiratory failure, dementia and pneumonia were the most significantly related comorbidities to mortality in the Down syndrome population. In the control population, respiratory failure, dementia and renal failure were the most significant disease contributors. When these contributors were analysed using multivariate analysis, heart failure, respiratory failure, pneumonia and epilepsy were the identified risk factors for in-hospital mortality in the Down syndrome population. Respiratory failure was the sole risk factor for mortality in the Down syndrome population [RR = 9.791 (1.6-59.9) P ≤ 0.05], when compared with the risk factors for mortality in the control population.

CONCLUSIONS

There is significant medical morbidity in Down syndrome. This morbidity contributes to the lower life expectancy. Respiratory failure is a risk factor for mortality in Down syndrome. We need to thoroughly investigate people with Down syndrome to ensure any treatable illnesses are well managed.

Hybrid III Lower Leg Injury Assessment Reference Curves Under Axial Impacts Using Matched-Pair Tests

The objective of the present study was to derive injury probability curves applicable to the Hybrid III dummy (also termed the Anthropomorphic Test Device, ATD) lower leg under axial impacts for military applications. A matched-pair approach was used. Axial impacts were delivered to below knee foot-ankle complex preparations of the lower leg of the ATD using pendulum and custom vertical accelerator devices. Military boot was used in some tests. Post mortem human surrogate (PMHS) preparations were used as matched-pair tests for injury outcomes. The alignment was such that the foot-ankle complex was orthogonal to the leg (below knee tibia-fibula complex), termed as the normal 90-90 posture. Injury outcomes from the biological surrogate focused on calcaneus and or distal tibia fractures with or without the involvement of articular surfaces. Peak lower tibia load cell forces were obtained from matched-pair dummy tests. Injury and force data were paired, censoring was assigned based on injury outcomes and survival analysis was done using the Weibull distribution to derive dummy-based probability curves. Mean peak forces were extracted at 5, 10, 20 and 50% probability levels. Normalized confidence interval sizes (NCIS) at ± 95% level were computed to determine the tightness-of-fit of the confidence bands. The NCIS data ranged from 0.34 to 0.78 and a peak force of 8.2 kN was associated at the ten percent injury probability level. Other data and curves are given in the body of the paper. The present Injury Assessment Reference Curves and Values (IARC and IARV) may be used in future tests for advancing safety in military environments. These survival analysis processes and IARC and IARV data may also be used in other applications.

Acute paediatric compartment syndrome of the hand caused by hereditary angiooedema

Compartment syndrome of the leg and forearm are well described in the literature. However, compartment syndrome of the hand is rare and in children it is even rarer. Atraumatic hand compartment syndrome has not to our knowledge been previously reported. We describe a case of an atraumatic compartment syndrome of the hand in a child who underwent an urgent fasciotomy. The child was diagnosed with hereditary angiooedema. We highlight a rare but serious complication of a hereditary disease not commonly seen by the surgical community. We hope that this report raises the awareness of this condition, thereby reducing delays in reaching a prompt diagnosis.

Phase I/II trial of a dendritic cell vaccine transfected with DNA encoding melan A and gp100 for patients with metastatic melanoma

This trial tested a dendritic cell (DC) therapeutic cancer vaccine in which antigen is loaded using a novel non-viral transfection method enabling the uptake of plasmid DNA condensed with a cationic peptide. Proof of principle required the demonstration of diverse T lymphocyte responses following vaccination, including multiple reactivities restricted through both major histocompatibility complex (MHC) class I and II. Patients with advanced melanoma were offered four cycles of vaccination with autologous DC expressing melan A and gp100. Disease response was measured using Response Evaluation Criteria in Solid Tumours. Circulating MHC class I- and II-restricted responses were measured against peptide and whole antigen targets using interferon-γ ELIspot and enzyme-linked immunosorbent assay assays, respectively. Responses were analyzed across the trial population and presented descriptively for some individuals. Twenty-five patients received at least one cycle. Vaccination was well tolerated. Three patients had reduction in disease volume. Across the trial population, vaccination resulted in an expansion of effector responses to both antigens, to the human leukocyte antigen A2-restricted modified epitope, melan A ELAGIGILTV, and to a panel of MHC class I- and II-restricted epitopes. Vaccination with mature DC non-virally transfected with DNA encoding antigen had biological effect causing tumour regression and inducing diverse T lymphocyte responses.

Selective axillary node sampling and radiotherapy to the axilla in the management of breast cancer

AIMS

Axillary treatment for patients with early-stage breast cancer can be associated with considerable morbidity. Techniques, such as axillary node sampling (ANS) and, more recently, sentinel node biopsy, in combination with radiotherapy have the potential to reduce toxicity. A retrospective review of axillary treatment in patients with early-stage breast cancer treated at our institution between 1997 and 2003 was carried out to assess the outcome and morbidity of ANS in combination with radiotherapy.

MATERIALS AND METHODS

The treatment policy was to carry out four-node, Edinburgh-style ANS except in those cases with either palpably enlarged nodes or cytological confirmation of involvement or with clinically obvious node involvement at surgery when level 2 axillary node clearance (ANC) was carried out. Patients with involved nodes after ANS received postoperative axillary radiotherapy.

RESULTS

In total, 381 patients were included, 331 received ANS and 50 received ANC. The median follow-up was 6.5 years and overall survival at 5 years was 84%. Pathologically involved nodes were found in 152/331 (50%) ANS patients and 43/50 (86%) ANC patients. The rate of local recurrence (breast or chest wall) at 5 years was 4% (95% confidence interval 1-17%) in the ANC group and 2% (95% confidence interval 1-4%) in the ANS group. The nodal recurrence rate of those undergoing ANS was 3% (11/331) compared with 6% (3/50) for those treated by ANC. The rate of clinically significant lymphoedema at 5 years was significantly higher (P=0.01) in the ANC arm: 18% (95% confidence interval 9-32%) compared with 5% (95% confidence interval 3-8%) in those treated by ANS. Thirty-one cases received additional supraclavicular fossa irradiation because of the involvement of more than four nodes on ANS, which may not have been available with sentinel node biopsy and has implications for current practice.

CONCLUSIONS

Selective ANS with the removal of a minimum of four nodes guides optimal locoregional treatment with good local control rates, low overall morbidity and may obviate the need for a second surgical procedure.

True aneurysm of the facial artery

We present a case of true facial artery aneurysm with no associated risk factors, which was non-pulsatile on presentation. This case is unique as the lesion was identified using computed tomography scanning, due to the unusual presentation. The vast majority of aneurysms of the head and neck have a traumatic aetiology, giving rise to false aneurysms; true aneurysms are extremely rare. We discuss the implications of such a lesion and its management.

Case of the month: Dislodged tracheo-oesophageal valve: importance of rapid replacement or stenting

Dislodgement of a tracheo-oesophageal prosthesis needs prompt action to ensure patency and prevent aspiration in patients with total laryngectomy. Failure to do so may lead to an unnecessary repeat tracheo-oesophageal puncture. This case report is about a patient who needed a repeat procedure under general anaesthetic. It highlights the need for emergency physicians to be aware of this not uncommon event in a patient with a laryngectomy and to refer them immediately for ENT review.

Influence of corneal asymmetry on the phakometric measurement of ocular surface alignment

Phakometric measurements of corneal and crystalline lens surface alignment are influenced by corneal asymmetry in which the corneal apex does not coincide with the limbal centre. The purpose of this study was to determine the horizontal separation (e) between these corneal landmarks. Measurements were made in 60 normal eyes (30 subjects) using the Orbscan IIz corneal analysis workstation. Our results show that both corneal landmarks typically coincide, so that e = 0, but that inter-subject variations of about +/-1 mm can be expected (so that the corneal apex may fall nasal or temporal to the visual axis). This suggests that no correction for corneal asymmetry is required when estimating average amounts of ocular alignment from samples of eyes but that the measurement of e is strongly recommended for measurements in individual eyes.

TRI-PLEDs: a case report

This case report shows an example of TRI-PLEDs, periodic discharges occurring independently on 3 different areas. The phenomenon of the PLED is briefly discussed.

The EEG changes during cardiac arrest: a case report

This case report of a patient with an irreversible cardiac arrest shows that the amplitude of the EEG, rather than its duration, when it becomes discontinuous, has a closer relationship with a diminished heart rate to a final arrest. These data may be helpful in determining the extent of cerebral demise of patients with a deteriorating cardiac function.