Objective:Population pharmacokinetics analysis explored the pharmacokinetics of anlotinib in children with soft tissue sarcomas (STS) and identified the optimal dose for children across various age brackets. Method:From 2021 to 2023, a single dose of anlotinib (4.62 mg/m2) was orally administered in 16 children with advanced STS in 8 days. Anlotinib plasma concentration was evaluated by LC-MS/MS. Pharmacokinetic models were developed using nonlinear mixed-effects modelling. The effect of predefined covariates on pharmacokinetic parameters was assessed. Results:Totally 128 samples from 16 children (aged 5-14) were collected for pop-PK analysis. The two-compartment model was most consistent with the data of oral anlotinib in pediatrics with advanced STS, and the relevant parameters were: Ka (h-1) 0.419; Vc/F (L) 760; Q (L∙h-1) 21.2; Vp/F (L) 547. Covariate screening showed that the clearance of anlotinib gradually increased with age in a sigmoidal relationship, the maximum CL/F was 15.7L∙h-1, and age of median clearance (Age50) was 6.84 years; the Vc/F increased linearly with BSA. Dose of 8 mg anlotinib for children aged 5-7, and 10 mg or 12 mg for children aged 8-10 would be expected to lead to a similar exposure of anlotinib compared with an adult patient receiving 12 mg. Conclusion:The population pharmacokinetics of orally administrated anlotinib were evaluated in pediatric advanced STS patients. BSA and age were significant physiologic factors on PK. A simulation of 8 mg anlotinib in children aged 5-7, 10 mg or 12 mg in 8-10 and 12 mg for children over 11 would get similar exposure of adults receiving 12mg.

Background: Retinoblastoma (RB) is the most common intraocular malignancy in infancy and childhood. Bone metastases are common and usually involve the skull and axial bones; limb bone metastases are rare. Herein, we evaluated the clinical features, image manifestations, treatment, and prognosis of patients with recurrent RB with limb bone metastasis and without central neural system involvement. Procedure: Clinical data of 5 patients with retinoblastoma who were diagnosed at the Department of Pediatrics in Beijing Tongren Hospital, between January 2015 and January 2021, were retrospectively analyzed. Results: Three males and two females were included (7 eyes: 4 stage E and 1 each of stage D, C, and B). The interval between symptom onset and bone metastasis was 12-102 months. Three cases were unilateral (2 left and 1 right), and two were bilateral. The most common symptom was pain. Three patients had bone marrow and lymph node metastasis. Three patients had single and two had multiple skeletal lesions. The main limb bones involved were the femur, humerus, talus, and ulna. Serum neuron specific enolase (NSE) was significantly elevated in 4 cases, and slightly elevated in 1 case; primary intravenous chemotherapy resulted in a decrease in NSE and gradual resolution of bone lesions. At the time of follow-up, 2 patients died and 3 were in complete remission. Conclusions: Regular lifelong follow-up of patients with RB is warranted to identify bone metastases. Clinicians should consider examination findings, imaging findings, and laboratory results to identify bone metastases and initiate appropriate treatment.

Background: Hepatic metastasis from retinoblastoma (RB) is rare. We evaluated clinical features, imaging manifestations, treatment, and prognosis in these patients. Procedure: Clinical data of five patients diagnosed with hepatic metastases of RB at the Department of Pediatrics in Beijing Tongren Hospital between January 2009 and January 2019 were analyzed retrospectively. Results: Two patients had bilateral lesions, while three had unilateral lesions. Among the seven eyes with lesions, six and one were classified as stage E and C, respectively (International Integrated Reporting Council staging). On computed tomography (CT), low-density foci were observed (three, multiple foci and two, single foci). After chemotherapy, tumor regression was observed in four patients, while there was no response in one patient. Three patients who underwent enucleation were at high risk for extensive choroidal invasion. All patients had severe disease with multiple system involvement, including central nervous system (CNS) and bone metastases. Neuron-specific enolase (NSE) and lactate dehydrogenase (LDH) levels were significantly elevated in all patients; after treatment, they decreased in four patients and remained unchanged in one patient with end-stage disease. Two patients died, with survival durations of 1 and 3 months following the diagnosis of hepatic metastasis. Three patients survived and continued treatment. Conclusion: Hepatic metastasis from RB is rare and usually occurs with CNS and bone metastases. On CT, hepatic foci could be indicated by low-density lesions with calcification. Chemotherapy could be effective for hepatic metastases. The prognosis of these patients is poor; however, hepatic metastasis is not a direct cause of death.