Sex-related differential susceptibility to ponatinib-induced cardiotoxicity and its relationship to modulation of Notch signaling in a murine model

Background

Ponatinib (PON), a tyrosine kinase inhibitor approved in chronic myeloid leukemia, has proven cardiovascular toxicity. Although sex is a risk factor for PON-induced cardiotoxicity in humans, little is known about its mechanisms in general, and sex-related mechanisms in particular.

Objectives

To determine the mechanisms of sex-related PON-induced cardiotoxicity and identify potential rescue strategies in a murine model.

Methods

24-months-old male and female C57B5 mice were treated with 3 mg/kg/day of PON or vehicle via oral gavage for 28 days, with/without siRNA-Notch1 or siRNA-scrambled via tail vein every 3 days.

Results

PON + scrambled siRNA-treated male mice had a higher number of TUNEL-positive cells, a higher percentage of senescence-associated β-galactosidase positive senescent cardiac areas, as well as a lower reactivity degree for the survival marker Bmi1 than female counterparts. Proteomics analysis of cardiac tissue showed upstream activation of nitric oxide synthase (NOS) type 2, downstream activation of cell death and production of reactive oxygen species in PON + scrambled siRNA- compared to vehicle or PON + Notch1 siRNA-treated male mice. Upstream analysis showed beta-estradiol activation, while downstream analysis showed activation of cell survival and inhibition of cell death in PON + scrambled siRNA compared to vehicle-treated female mice. PON + scrambled siRNA-treated mice also showed a downregulation of cardiac actin, which was more marked in male; as well as vessel density, which was more marked in female mice. Female hearts showed a greater extent of cardiac fibrosis than male counterparts at baseline, with no significant changes after PON treatment. In contrast, PON + scrambled siRNA-treated mice had less fibrosis than vehicle or PON + Notch1-siRNA-treated mice. Left ventricular systolic dysfunction shown in PON + scrambled siRNA-treated male mice and - to a lesser extent - by female mice was similarly reversed in both PON + Notch1-siRNA-treated male and female mice (Table 1).

Conclusions

We found a sex-related differential susceptibility and Notch1 modulation in PON-induced cardiotoxicity. This can improve our understanding of sex-related differences and help identify biomarkers in PON cardiotoxicity.

Funding Acknowledgement

Type of funding sources: None.

Ponatinib induces vascular toxicity through the Notch-1 signaling pathway

Background

Ponatinib, a third-generation tyrosine kinase inhibitor (TKI), is the only approved TKI that is effective against T315I mutations in patients with chronic myeloid leukemia (CML). Specific activation of Notch signaling in CML cells by ponatinib can be considered as the “on-target effect” on the tumor and represents a therapeutic approach for CML. Nevertheless, ponatinib-induced vascular toxicity remains a serious concern, with underlying mechanisms poorly understood.

Aims

We aimed at determining mechanisms of ponatinib-induced vascular toxicity, defining associated signaling pathways and identifying potential rescue strategies.

Methods and results

We exposed human umbilical endothelial cells (HUVECs) to ponatinib or vehicle in the presence or absence of the neutralizing factor anti-Notch-1 antibody for exposure times of 0–72 hours. Label-free proteomics and network analysis showed that protein cargo of HUVECs treated with ponatinib triggered apoptosis, and inhibited vasculature development (Fig. 1). We validated the proteomic data showing the inhibition of matrigel tube formation, an upregulation of cleaved caspase-3 and a downregulation of phosphorylated AKT and phosphorylated eNOS. We delineated the signaling of ponatinib-induced vascular toxicity demonstrating that ponatinib inhibits endothelial survival, reduces angiogenesis and induces endothelial senescence and apoptosis via Notch-1 pathway.

Conclusion

Ponatinib induced endothelial toxicity in vitro. Hyperactivation of Notch-1 in the vessels can lead to abnormal vascular development and vascular dysfunction. By hyperactivating Notch-1 in the vessels, ponatinib exerts an “on-target off turmor effect”, which leads to deleterious effects and may explain the drug's vasculotoxicity. Selective blockade of Notch-1 prevented ponatinib-induced vascular toxicity.

Figure 1

Funding Acknowledgement

Type of funding source: None

Somatosensory cortical activation identified by functional MRI in preterm and term infants

Functional MRI (fMRI) has not previously been used systematically to investigate brain function in preterm infants. We here describe statistically robust and reproducible fMRI results in this challenging subject group using a programmable somatosensory stimulus synchronized with MR image acquisition which induced well-localized positive blood oxygen level dependent (BOLD) responses contralateral to the side of the stimulation in: 11 preterm infants (median post menstrual age 33 weeks and 4 days, range 29+1 to 35+3); 6 control infants born at term gestational age; and 18 infants born preterm (median gestational age at birth 30 weeks and 5 days, range 25+4 to 36+0) but studied at term corrected gestational age. Bilateral signals were identified in 8 of the ex-preterm infants at term age. Anatomical confirmation of appropriate activations was provided with diffusion tensor imaging (DTI) based tractography which identified connecting pathways from the regions of activation through the ipsilateral corticospinal tracts and posterior limb of the internal capsule. These results demonstrate that it is possible to reliably identify positive BOLD signals in the infant brain and that fMRI techniques can also be applied in the study of preterm infants.

Review of the first 1502 cases of ECG-ST waveform analysis during labour in a teaching hospital

OBJECTIVE

To assess the impact of introduction of the STAN monitoring system.

STUDY DESIGN

Prospective observational study.

SETTING

Tertiary referral labour ward, St George's Hospital, London.

POPULATION

High-risk term pregnancies.

METHODS

We report all consecutive cases of intrapartum monitoring using the STAN S 21 fetal heart monitor. Cases with adverse neonatal outcome were evaluated in relation to the ST waveform analysis and cardiotocography (CTG).

MAIN OUTCOME MEASURES

Cord artery metabolic acidosis, neonatal encephalopathy (NNE) and reasons behind cases with poor outcome.

RESULTS

Between 2002 and 2005, there were 1502 women monitored by STAN. Based on combined STAN analysis in the 1502 women, action was indicated in 358 women (23.8%), while in 1108 women (73.8%) no action was indicated. Traces were not interpretable in 36 women (2.4%). Of the 836 cases (55.7%) where cord blood gases were available, there were 23 cases (2.8%) of metabolic acidosis and 16 of these (70%) were identified by STAN. Overall, there were 14 cases of NNE monitored by STAN. Retrospective analysis of these highlights human errors, such as poor CTG interpretation, delay in taking appropriate action and not following the guidelines.

CONCLUSIONS

Our experience suggests the need for more intense training on interpretation of CTG and strict adherence to guidelines.

Role of amnioinfusion in the management of premature rupture of the membranes at <26 weeks' gestation

OBJECTIVE

We sought to evaluate whether serial amnioinfusions for persistent oligohydramnios can affect the perinatal and long-term outcomes in extreme cases of preterm premature rupture of membranes.

STUDY DESIGN

All singleton pregnancies with preterm premature rupture of membranes at <26 weeks' gestation and lasting >4 days between January 1991 and June 1998 were included. Amniotic fluid volume was assessed as the maximum cord-free pocket with serial ultrasonographic examinations. Consenting women with persistent (>4 days) oligohydramnios (amniotic fluid </=2 cm) received serial transabdominal amnioinfusions to maintain an amniotic fluid pocket >2 cm. The pregnancy, neonatal, and long-term neurologic outcomes of the cases that spontaneously maintained a median amniotic fluid pocket >2 cm (amnioinfusion-not-necessary group) were compared with those of women with oligohydramnios who underwent amnioinfusion but continued to have a median amniotic fluid pocket after preterm premature rupture of membranes </=2 cm (persistent oligohydramnios group) and with those of women in whom oligohydramnios was alleviated by the procedure for at least 48 hours (successful amnioinfusion group). Statistical analysis included the Wilcoxon rank-sum test and the Fisher exact test, with a 2-tailed P <.05 considered significant.

RESULTS

Among the 49 women included in the study, 13 (26.5%) did not have oligohydramnios, the neonatal survival rate was 92%, and normal fetal lung development and neurologic outcome were achieved in all survivors. The remaining 36 women had oligohydramnios, and all underwent serial amnioinfusions, which successfully restored a median amniotic fluid pocket >2 cm for >/=48 hours in 11 (30%) patients. This successful amnioinfusion group was comparable with the persistent oligohydramnios group (n = 25) in gestational age at first amnioinfusion (median, 20.2 weeks; range, 16-25.6 weeks; vs median, 20.3 weeks; range, 16.5-24.2 weeks; P =.4), number of amnioinfusions (median, 3; range, 1-9; vs median, 3; range, 1-5; P =.4), and interval between amnioinfusions (median, 6 days; range, 4-14 days; vs median, 8 days; range, 6-43 days; P =. 1). However, patients in the persistent oligohydramnios group had a significantly shorter interval to delivery, lower neonatal survival (20%), and higher rates of pulmonary hypoplasia (62%) and abnormal neurologic outcomes (60%) than the patients in the groups in which amnioinfusion was not necessary or was successful (all P </=.01).

CONCLUSION

Pregnancies with preterm premature rupture of membranes-related oligohydramnios at <26 weeks' gestation in which serial amnioinfusions successfully alleviate oligohydramnios have a perinatal outcome that is significantly better than the outcome in those with persistent oligohydramnios and is comparable with gestations with preterm premature rupture of membranes in which oligohydramnios never develops.

Biophysical profile in predicting acute ascending infection in preterm rupture of membranes before 32 weeks

OBJECTIVE

To assess the performance of the biophysical profile (BPP) and its components within 24 hours of delivery in predicting histopathologic evidence of severe acute placental inflammation in women with premature rupture of membranes (PROM) before 32 weeks' gestation.

METHODS

We examined placentas from a series of consecutive, nonanomalous, live-born, singleton infants delivered before 32 weeks' gestation after PROM. In 166 cases, biophysical profiles (BPP) were done within 24 hours of birth. Histologic evidence of acute inflammation was assessed in the maternal (amnion) and fetal (chorionic and umbilical cord vessels) compartments, and scored on a severity scale of 0-4 by a single pathologist masked to clinical data. The presence and severity of acute inflammation was related to BPP results and its individual components.

RESULTS

The overall prevalence of severe acute inflammation, ie, a score of 3 or 4, was 59% (98 of 166). In 30 (18%) cases it was present in the amnion, in 49 (30%) cases in chorionic or umbilical cord vessels, and in 19 (11%) cases in maternal and fetal compartments. There was no association between abnormal BPP score and presence or absence of severe acute placental inflammation (48% versus 46%, P =.7). Our study had a 90% power to detect a 0.26 difference between them. When rates of abnormal BPP scores were compared in cases with different degrees of acute inflammation in the maternal, fetal, or both compartments, no association was found. When the individual components of the BPP were analyzed in relation to site and severity of acute inflammation, no association was detected.

CONCLUSION

We did not find evidence of a dose-response relationship between acute placental inflammation and BPP score or its individual components in cases of PROM with infants delivered before 32 weeks. Mediators other than infection might affect BPP in preterm PROM.

Successful outcome after antibiotic treatment of postamniocentesis membrane rupture and chorioamnionitis in multiple pregnancy

Postamniocentesis chorioamnionitis is usually managed with induction of labor to prevent maternal sepsis and related morbidity and mortality. We report a case of chorioamnionitis in a triplet pregnancy after midtrimester genetic amniocentesis, in which multiple antibiotic treatment (ampicillin 2 g i.v. loading dose followed by 1 g i.v. every 6 hr; clindamycin 900 mg i.v. every 8 hr; gentamicin 120 mg i.v. loading dose followed by 100 mg i.v. every 8 hrs; and erythromycin 500 mg i.v. every 6 hr) for 7 days and delivery of the presumably infected triplet A successfully reversed the clinical symptomatology, allowing prolongation of pregnancy until 26 weeks and survival of the remaining fetuses. At age 2 years, both infants are doing well and are meeting their developmental milestones. The viable outcome of this management strategy suggests that antibiotic treatment and expectancy may be an option in selected cases of postamniocentesis chorioamnionitis in multiple pregnancies.

[Risk factors and neonatal outcomes in shoulder dystocia]

BACKGROUND

Shoulder dystocia (SD) is a rare obstetrical complication but linked with a high perinatal morbidity and mortality rate. SD has been associated to a series of maternal and fetal risk factors due to a multifactorial etiology. This study analyzes the incidence of SD, its morbidity and associated risk factors.

METHODS

Cases of SD occurred at the St. Gerardo Hospital (Monza) between January 1992 trough December 1997 have been retrospectively reviewed. Obstetrical and feto-neonatal data regarding cases of SD were compared to data regarding all the cephalic vaginal deliveries occurred in the same period in our Center.

RESULTS

A total of 14,157 cephalic vaginal deliveries were included in this study, of these 21 infants (0.15%) had SD. A significantly higher incidence of SD cases was found in fetal macrosomia, maternal diabetes, induction of labor by PGE2, use of obstetrical vacuum, length of first stage of labor > 4 hours in multiparas and > 8 hours in nulliparas, and length of second stage > 60 minutes, regardless of parity. A closed association was also observed between SD and birth trauma as brachial plexus injury and humerus fracture.

CONCLUSION

The incidence of SD in our population (0.15%) is below the average reported in the literature (0.37-1.1%). The well-known risk factors, whose low positive predictive value can nevertheless modify obstetrical management, are confirmed.