Alternative formulations of sorafenib for use in children

[Preventive and therapeutic strategies for relapse after hematopoietic stem cell transplant for pediatric AML (SFGM-TC)]

Treatment of pediatric high-risk acute myeloid leukemia (AML), defined either on molecular or cytogenetic features, relies on bone marrow transplant after cytologic remission. However, relapse remains the first post-transplant cause of mortality. In this 13th session of practice harmonization of the francophone society of bone marrow transplantation and cellular therapy (SFGM-TC), our group worked on recommendations regarding the management of post-transplant relapse in AML pediatric patients based on international literature, national survey and expert opinion. Overall, immunomodulation strategy relying on both measurable residual disease (MRD) and chimerism evaluation should be used for high-risk AML. In very high-risk (VHR) AML with a 5-year overall survival ≤30 %, a post-transplant maintenance should be proposed using either hypomethylating agents, combined with DLI whenever possible, or FLT3 tyrosine kinase inhibitors if this target is present on leukemia cells. In the pre-emptive or early relapse settings (< 6 months post-transplant), treatments combining DLI, Azacytidine and Venetoclax should be considered. Access to phase I/II trails for targeted therapies (menin, IDH or JAK inhibitors) should be discussed in each patient according to the underlying molecular abnormalities of the disease.

Pharmacokinetic Boosting of Kinase Inhibitors

(1) Introduction: Pharmacokinetic boosting of kinase inhibitors can be a strategy to enhance drug exposure and to reduce dose and associated treatment costs. Most kinase inhibitors are predominantly metabolized by CYP3A4, enabling boosting using CYP3A4 inhibition. Kinase inhibitors with food enhanced absorption can be boosted using food optimized intake schedules. The aim of this narrative review is to provide answers to the following questions: Which different boosting strategies can be useful in boosting kinase inhibitors? Which kinase inhibitors are potential candidates for either CYP3A4 or food boosting? Which clinical studies on CYP3A4 or food boosting have been published or are ongoing? (2) Methods: PubMed was searched for boosting studies of kinase inhibitors. (3) Results/Discussion: This review describes 13 studies on exposure boosting of kinase inhibitors. Boosting strategies included cobicistat, ritonavir, itraconazole, ketoconazole, posaconazole, grapefruit juice and food. Clinical trial design for conducting pharmacokinetic boosting trials and risk management is discussed. (4) Conclusion: Pharmacokinetic boosting of kinase inhibitors is a promising, rapidly evolving and already partly proven strategy to increase drug exposure and to potentially reduce treatment costs. Therapeutic drug monitoring can be of added value in guiding boosted regimens.

Pharmacokinetically guided dosing of oral sorafenib in pediatric hepatocellular carcinoma: A simulation study

Sorafenib improves outcomes in adult hepatocellular carcinoma; however, hand foot skin reaction (HFSR) is a dose limiting toxicity of sorafenib that limits its use. HFSR has been associated with sorafenib systemic exposure. The objective of this study was to use modeling and simulation to determine whether using pharmacokinetically guided dosing to achieve a predefined sorafenib target range could reduce the rate of HFSR. Sorafenib steady‐state exposures (area under the concentration curve from 0 to 12‐h [AUC_0–>12 h]) were simulated using published sorafenib pharmacokinetics at either a fixed dosage (90 mg/m²/dose) or a pharmacokinetically guided dose targeting an AUC_0–>12 h between 20 and 55 h µg/ml. Dosages were either rounded to the nearest quarter of a tablet (50 mg) or capsule (10 mg). A Cox proportional hazard model from a previously published study was used to quantify HFSR toxicity. Simulations showed that in‐target studies increased from 50% using fixed doses with tablets to 74% using pharmacokinetically guided dosing with capsules. The power to observe at least 4 of 6 patients in the target range increased from 33% using fixed dosing with tablets to 80% using pharmacokinetically guided with capsules. The expected HFSR toxicity rate decreased from 22% using fixed doses with tablets to 16% using pharmacokinetically guided dosing with capsules. The power to observe less than 6 of 24 studies with HFSR toxicity increased from 51% using fixed dosing with tablets to 88% using pharmacokinetically guided with capsules. Our simulations provide the rationale to use pharmacokinetically guided sorafenib dosing to maintain effective exposures that potentially improve tolerability in pediatric clinical trials.

Sorafenib in pediatric hepatocellular carcinoma from a clinician perspective

Hepatocellular Carcinoma (HCC) is a rare tumor in children and normally carries poor outcomes. The most frequently employed chemotherapy regimen includes cisplatin and doxorubicin (PLADO), but this combination offers limited efficacy. Sorafenib is a multi-tyrosine kinase inhibitor which, following positive studies in adults with HCC, has begun to be introduced in conjunction with PLADO in pediatric oncology with some encouraging results. Based on these findings, the use of sorafenib is become more common in children with unresectable and/or metastatic HCC. The care of patients receiving sorafenib requires appropriate expertise and standardized pediatric guidelines are lacking. An increasing number of children with HCC are expected to receive sorafenib in the years to come. Pediatric oncology clinicians have a key role in identifying side effects early and clinicians caring for children receiving sorafenib need to be familiar with these. This review article provides suitable and practical information on sorafenib for educational development to optimize clinical care and facilitate enhanced patient/parent education. The article addresses specific areas including mechanisms of action, pre-clinical and clinical evidence, dosing and drug administration and toxicities of sorafenib. Clinical research and recommendations for managing sorafenib-related side effects are discussed. Underpinned by research, this article provides pediatric oncology clinicians with the knowledge required to deliver optimal care to children receiving sorafenib.

Phase I expansion cohort to evaluate the combination of bevacizumab, sorafenib and low-dose cyclophosphamide in children and young adults with refractory or recurrent solid tumours

BACKGROUND

Angiogenesis is critical for tumour growth and metastasis. Dual inhibition of vascular endothelial growth factors and platelet-derived growth factor receptors suppresses angiogenesis. This expansion cohort of a phase I study targeted angiogenesis with sorafenib, bevacizumab and low-dose cyclophosphamide in children and young adults with recurrent solid tumours.

METHODS

An expansion cohort including patients with refractory or recurrent solid tumours was enrolled and received bevacizumab (15 mg/kg IV, day 1), sorafenib (90 mg/m² po twice daily, days 1-21) and low-dose cyclophosphamide (50 mg/m² po daily, days 1-21). Each course was 21 days. Toxicities were assessed using Common Terminology Criteria for Adverse Events, v3.0, and responses were evaluated by Response Evaluation Criteria in Solid Tumors criteria. Serial bevacizumab pharmacokinetic (PK) studies were performed during course 1.

RESULTS

Twenty-four patients (15 males; median age 14.5 yrs; range 1-22 yr) received a median of 6 courses (range 1-18). Twelve patients had a bone or soft tissue sarcoma. The most common grade III/IV non-haematologic toxicities were hypertension (N = 4), hand/foot rash (N = 3) and elevated lipase (N = 3). The most common grade III/IV haematologic toxicities were neutropenia (N = 7) and lymphopenia (N = 17). Three patients (2 synovial sarcoma, 1 rhabdoid tumour) achieved a partial response and 18 had stable disease. The progression-free survival at 3 and 6 months were 78.1% (95% confidence interval [CI] 60.6-95.6%) and 54% (95% CI 30.2-78.2%), respectively. Bevacizumab PKs in 15 patients was similar to published adult PK results.

CONCLUSIONS

Intravenous bevacizumab combined with oral sorafenib and low-dose cyclophosphamide was tolerated and demonstrated promising activity in a subset of childhood solid tumours.

Molecular mechanisms and therapeutic targets in neuroblastoma

Neuroblastoma is the most common extracranical tumor of childhood and the most deadly tumor of infancy. It is characterized by early age onset and high frequencies of metastatic disease but also the capacity to spontaneously regress. Despite intensive therapy, the survival for patients with high-risk neuroblastoma and those with recurrent or relapsed disease is low. Hence, there is an urgent need to develop new therapies for these patient groups. The molecular pathogenesis based on high-throughput omics technologies of neuroblastoma is beginning to be resolved which have given the opportunity to develop personalized therapies for high-risk patients. Here we discuss the potential of developing targeted therapies against aberrantly expressed molecules detected in sub-populations of neuroblastoma patients and how these selected targets can be drugged in order to overcome treatment resistance, improve survival and quality of life for these patients and also the possibilities to transfer preclinical research into clinical testing.

Prediction of Apparent Oral Clearance of Small-Molecule Inhibitors in Pediatric Patients

The purpose of this study was to build regression models for the prediction of apparent oral clearance (CL/F) for small-molecule inhibitors in the pediatric population using data obtained from adults. Two approaches were taken; a simple allometric regression model which considers no interdrug or interindividual variability and an allometric regression model with mixed-effects modeling where some variability parameters are included in the model. Average CL/F values were obtained for 15 drugs at various dosages from 31 literatures (a total of 139 data sets) conducted in adults and for 15 drugs from 26 literatures (62 data sets) conducted in children. Data were randomly separated into the "modeling" or "validation" data set, and the 2 allometric regression models were applied to the modeling data set. The predictive ability of the models was examined by comparing the observed and model-predicted CL/F in children using the validation data set. The percentage root mean square error was 17.2% and 26.3% in the simple allometric regression model and the allometric regression model with mixed-effects modeling, respectively. The predictive ability of the 2 models seems acceptable, suggesting that they could be useful for predicting the CL/F of new small-molecule inhibitors and for determining adequate doses in clinical pharmacotherapy for children.