Cardiotoxicity of childhood cancer treatment: update and current knowledge on long-term follow-up

Pharmacogenomics in Children

Historically genetics has not been considered when prescribing drugs for children. However, it is clear that genetics are not only an important determinant of disease in children but also of drug response for many important drugs that are core agents used in the therapy of common problems in children. Advances in therapy and in the ethical construct of children's research have made pharmacogenomic assessment for children much easier to pursue. It is likely that pharmacogenomics will become part of the therapeutic decision-making process for children, notably in areas such as childhood cancer where weighing benefits and risks of therapy is crucial.

The histone deacetylase inhibitor PCI-24781 as a putative radiosensitizer in pediatric glioblastoma cell lines

BACKGROUND

Glioblastoma (GBM) is considered to be one of the most aggressive tumors of the central nervous system (CNS). Even with the use of modern treatment protocols, the prognosis remains reserved, with children with GBM having a mean survival of 12-15 months.

METHODS

In the present study we investigated the potential radiosensitizing effect of PCI-24781, a potent pan-histone deacetylase inhibitor (HDACi), on the SF188 and KNS42 cell lines of pediatric GBM. Cell proliferation rates, clonogenicity and apoptosis were compared in the presence and absence of treatment with PCI-24781. We also compared the clonogenicity rates of the irradiated SF188 and KNS42 cell lines with or without previous treatment with PCI-24781 at the doses of 0.25-16 μM. In addition, we investigated the effects of PCI-24781 on the expression of some of the main proteins responsible for the repair of double-strand DNA breaks caused by irradiation.

RESULTS

The inhibitor blocked cell proliferation, induced death by apoptosis and reduced the colony forming capacity of the cell lines, both of them showing a significant decrease of colony formation at all irradiation doses. The expression of the Rad51 protein, important for the homologous recombination (HR) repair pathway, and of the DNA-PKcs, Ku70 and Ku86 proteins, important for the non-homologous end joining (NHEJ) repair pathway, was more reduced when the irradiated cell line was previously treated with PCI-24781 than when it was treated exclusively with radiotherapy.

CONCLUSIONS

These findings demonstrate that HDACi PCI-24781 has a radiosensitizing profile that compromises the repair of double-strand DNA breaks in cells of pediatric GBM treated with radiotherapy.

Cardiovascular Disease Risk Profiles in Survivors of Adolescent and Young Adult (AYA) Cancer: The Kaiser Permanente AYA Cancer Survivors Study

PURPOSE

To describe the epidemiology and risk factors for cardiovascular disease (CVD) in survivors of adolescent and young adult (AYA) cancer.

METHODS

We identified a retrospective cohort of 2-year survivors of AYA cancer who were diagnosed between the ages of 15 to 39 years (1998 to 2009) at Kaiser Permanente Southern California. A comparison group without cancer was selected and matched 10:1 to cancer survivors on the basis of age, sex, Kaiser Permanente Southern California membership, and calendar year. Patients were followed through December 31, 2012, for coronary artery disease, heart failure, and stroke. Time-dependent Poisson regression was used to evaluate the effect that cancer survivorship had on the risk of developing CVD, adjusted for cardiovascular risk factors (CVRFs; ie, diabetes, hypertension, and dyslipidemia), ethnicity, smoking, and overweight/obesity. Among cancer survivors, mortality risk by CVD status was examined using Cox regression.

RESULTS

A total of 5,673 2-year survivors of AYA cancer and 57,617 comparison patients were included, representing 24,839 and 239,073 person-years of follow-up, respectively. Overall, cancer survivors had more than two-fold risk of developing CVD (adjusted incidence rate ratio, 2.37; 95% CI, 1.93 to 2.93) when compared with patients without cancer; survivors of leukemia and breast cancer were at the highest risk (adjusted incidence rate ratio, 4.23; 95% CI, 1.73 to 10.31; and 3.63; 95% CI, 2.41 to 5.47, respectively) of developing CVD. Having any of the CVRFs increased the risk of CVD in cancer survivors. Cancer survivors who developed CVD had an 11-fold increased overall mortality risk (hazard ratio, 10.9; 95% CI, 8.1 to 14.8) when compared with survivors without CVD.

CONCLUSION

Survivors of AYA cancer are at increased risk for developing CVD. Survival after CVD onset is compromised, and CVRFs are independent modifiers of CVD risk. These data form the basis for identifying high-risk individuals and proactive management of CVRFs.

Pharmacogenomics and adverse drug reactions in children

Adverse drug reactions are a common and important complication of drug therapy in children. Over the past decade it has become increasingly apparent that genetically controlled variations in drug disposition and response are important determinants of adverse events for many important adverse events associated with drug therapy in children. While this research has been difficult to conduct over the past decade technical and ethical evolution has greatly facilitated the ability of investigators to conduct pharmacogenomic studies in children. Some of this research has already resulted in changes in public policy and clinical practice, for example in the case of codeine use by mothers and children. It is likely that the use of pharmacogenomics to enhance drug safety will first be realized among selected groups of children with high rates of drug use such as children with cancer, but it also likely that this research will be extended to other groups of children who have high rates of drug utilization and as well as providing insights into the mechanisms and pathophysiology of adverse drug reactions in children.

Prevalence of cardiovascular risk factors in long-term survivors of childhood cancer: 16 years follow up from a prospective registry

BACKGROUND

Childhood cancer survivors (CCSs) have an increased risk of overweight and dyslipidaemia, but the distribution and the potential relationships between anticancer therapies and cardiovascular risk factors have been heterogeneously and not prospectively described.

METHODS

All consecutive CCSs with primary cancer diagnosed between 1973-2007 and subsequently referred to our outpatient clinic were enrolled. Hypercholesterolaemia (total cholesterol >200 and/or low density lipoprotein (LDL)>160 mg/dl) was the primary end point, hypertriglyceridaemia (triglycerides >200 mg/dl) and body mass index >30 kg/m(2) the secondary end points. Cox multivariate adjustments were performed to account for differences in cancer and treatments.

RESULTS

A total of 340 patients were included (197 male, 143 female; mean age at last follow-up 24.1 ± 3.2). The most common diagnosis were haematological malignancies (n = 227) and brain tumours (n = 51). After a median follow-up of 16.1 years, hypercholesterolaemia was diagnosed in 67 CCSs (20%), hypertriglyceridaemia in 20 CCSs (6%) and obesity in 28 CCSs (8%). Total body irradiation and growth hormone deficiency increased the risk of both hypercholesterolaemia (hazard ratio (HR) = 2.7; confidence interval (CI) 1.2-4.4 and HR = 2.3; CI 1.1-4.9; all p < 0.05) and hypertriglyceridaemia (HR = 6.5; CI 1.4-31 and HR = 7.2; CI 1.1-43; all p < 0.05). The risk of hypercholesterolaemia was also higher in CCSs who underwent autologous haematopoietic stem cell transplantation (HR = 3.2; CI 1.7-5.9; p < 0.001) or platinum-based chemotherapy (HR = 2.7; CI 1.5-4.9; p < 0.001), whereas a previous diagnosis of brain tumour (HR = 10; CI 1.2-45; p < 0.05) and anthracyclines exposure (HR = 1.3; CI 1.2-26; p < 0.05) significantly predicted obesity.

CONCLUSION

CCSs show a high and variable risk for developing dyslipidaemia and obesity, depending on cancer diagnosis and treatments. Therefore, they need accurate and tailored control of their cardiovascular risk profile.

New drug development in childhood cancer

PURPOSE OF REVIEW

Future advances in childhood cancer treatment will pivot on developing biology-driven new drug development pathways that build on current knowledge of oncogenic pathways; however, we need to address major barriers to accessing new drugs for clinical evaluation in childhood cancers.

RECENT FINDINGS

Through legislative change, substantial incentives to the pharmaceutical industry to invest in the ultra-rare diseases, such as childhood cancers, have encouraged greater engagement with paediatric oncology drug development consortia. Disappointingly, this has not translated into paediatric-focussed drug development. Adult disease-driven drug development will continue to dominate until biology/target-driven approaches prevail.There are specific challenges to undertaking early drug development trials in children with incurable disease. The balance between risk and benefit for a child participating in trials wherein the chance of clinical benefit is indeterminate has the potential for unrealistic optimism by both physicians and families. Importantly, innovative trial designs that assess safety and maximize information on potential efficacy from small patient numbers are needed.

SUMMARY

International collaboration in early phase trial consortia addresses these challenges. Academic networks concentrating early phase trials expertise and delivery of innovative trial designs will maximize appropriate selection of drugs that can translate into therapeutic advantage when incorporated into standard care.

Pharmacogenomics in children

Historically genetics has not been considered when prescribing drugs for children. However, it is clear that genetics are not only an important determinant of disease in children but also of drug response for many important drugs that are core agents used in the therapy of common problems in children. Advances in therapy and in the ethical construct of children's research have made pharmacogenomic assessment for children much easier to pursue. It is likely that pharmacogenomics will become part of the therapeutic decision making process for children, notably in areas such as childhood cancer where the benefits and risks of therapy are considerable.

Iron overload in children undergoing cancer treatments

BACKGROUND

Iron overload is responsible for severe morbidity and mortality in polytransfused patients. Although repeated blood transfusions are needed during the treatment of most cancers, pediatric patients are not routinely screened for subsequent iron overload.

PROCEDURE

Seventy-five patients were identified as candidates for cancer treatment and enrolled prospectively in a yearly protocol including a cardiac and liver magnetic resonance imaging coupled with ferritin level measurements. Patients were divided into four groups using the intensity of treatment rating (ITR-3).

RESULTS

Fifty-nine patients reached 1-year of follow-up and liver iron overload was found in up to 66% of them. Such overload correlated with the total volume of red blood cells transfused and persisted at least 2 years after the initiation of therapy. Moderate myocardial overload was also, but less frequently (14%), observed in these patients.

CONCLUSIONS

Our study demonstrated that severe liver iron overload as well as moderate myocardial iron overload can be found 1 year after cancer treatment and that this overload persists overtime. The patients with higher ITR and those who have received more than a liter of blood red cells per square meter, regardless of their diagnosis or ITR, are at risk of iron overload and should be screened carefully.