Pharmacokinetics of PEGasparaginase in Infants with Acute Lymphoblastic Leukemia.

BACKGROUND: PEGasparaginase is known to be a critical drug for treating pediatric acute lymphoblastic leukemia (ALL), however, there is insufficient evidence to determine the optimal dose for infants who are less than one year of age at diagnosis. This international study was conducted to identify the pharmacokinetics of PEGasparaginase in infants with newly diagnosed ALL and gather insight into the clearance and dosing of this population. METHODS: Infants with ALL who received treatment with PEGasparaginase were included in our population pharmacokinetic assessment employing non-linear mixed effects modelling (NONMEM). RESULTS: 68 infants with ALL, with a total of 388 asparaginase activity samples, were included. PEGasparaginase doses ranging from 400 to 3,663 IU/m2 were administered either intravenously or intramuscularly. A one-compartment model with time-dependent clearance, modeled using a transit model, provided the best fit to the data. Body weight was significantly correlated with clearance and volume of distribution. The final model estimated a half-life of 11.7 days just after administration, which decreased to 1.8 days 14 days after administration. Clearance was 19.5% lower during the post-induction treatment phase compared to induction. CONCLUSION: The pharmacokinetics of PEGasparaginase in infants diagnosed under one year of age with ALL is comparable to that of older children (1-18 years). We recommend a PEGasparaginase dosing at 1,500 IU/m2 for infants without dose adaptations according to age, and implementing therapeutic drug monitoring as standard practice.

Hypersensitivity reactions to asparaginase therapy in acute lymphoblastic leukemia: immunology and clinical consequences.

Asparaginase is commonly used in combination therapy of acute lymphoblastic leukemia. However, as an immunogenic protein, hypersensitivity reactions (HSRs) during asparaginase therapy are frequent, indicating the development of anti-asparaginase antibodies. These can be associated with diminished clinical effectiveness, including poorer survival. Therapeutic drug monitoring of serum asparaginase activity to confirm complete asparagine depletion is therefore crucial during asparaginase therapy. Switching to alternative types of asparaginase is recommended for patients experiencing HSRs or silent inactivation; those with HSRs or silent inactivation on Escherichia coli-derived asparaginases should switch to another preparation. However, prior global shortages of Erwinia asparaginase highlight the importance of alternative non-E. coli-derived asparaginase, including recombinant Erwinia asparaginase.

Asparaginase is commonly used as a part of a multidrug regimen for acute lymphoblastic leukemia treatment. As foreign proteins, asparaginases have the potential to induce immune responses known as hypersensitivity reactions (HSRs), which can range from a mild rash to a severe allergic reaction. Here, we provide an overview of HSRs and their prevalence in asparaginase-based therapies, and clinical approaches to reduce HSRs. We also review the current understanding of cellular and molecular mechanisms of HSRs, consequences of HSRs and current recommendations for the management of immune reactions to asparaginase. Prior global shortages of Erwinia asparaginase due to manufacturing and supply issues have limited access of asparaginase treatment to patients. In this context, newer therapies have recently been developed.

Vaccination in children with chronic severe neutropenia - review of recommendations and a practical approach.

While the management of childhood neutropenia associated with a modifiable factor should be appropriate for the primary cause, there are misconceptions regarding the management of severe congenital neutropenia, immune neutropenia and cases classified as "idiopathic". Antibiotic prophylaxis or granulocyte-colony stimulating factor (G-CSF) are prescribed by specialists in pediatric hematology or immunology, whereas immunization may be conducted by primary care physicians should clear recommendations by provided. There is a belief that severe neutropenia, as an immunodeficiency, is associated with compromised effectiveness and increased rate of complications of immunization. The immunization might be delayed or omitted, increasing the risk of unnecessary infection. We discuss the available data and recommendations regarding vaccination of children with chronic severe neutropenia. While there are virtually no studies addressing the safety and effectiveness of vaccination in neutropenia, expert opinions provide information on immunization policy in "phagocytic cells defects" or explicitly neutropenia. There are no contraindications for inactivated vaccines in neutropenia. Live bacterial vaccines are contraindicated. While in general the vaccination with live viral vaccines is encouraged, occasionally neutropenia might be associated with defects of adaptive immunity, which would preclude the administration of such vaccines. Although this should be easily phenotypically identified, we propose assessing immunoglobulin levels and performing a low-cost flow cytometry test for major lymphocyte subpopulations to exclude significant defects in adaptive immunity before administration of live viral vaccines to such patients. This can improve the adherence of patients' guardians and physicians to proposed vaccination policy and the professional and legal safety associated with the procedure.

Uncommon reasons of the digestive tract-related paraneoplastic syndromes in children with neuroblastic tumors: three case reports.

AIM OF THE STUDY: presentation of the uncommon paraneoplastic syndromes related to the gastrointestinal tract that may occur in children with neuroblastic tumors and their impact on the disease course. MATERIAL AND METHODS: Retrospective analysis of three cases of patients mainly with digestive tract-related symptoms, who were originally admitted to the gastroenterology department from 2013 to 2016 and were finally diagnosed with neuroblastic tumors. RESULTS: The clinical data analysis showed that the symptoms from gastrointestinal tract were dominant in analyzed subjects. The first case is a girl with weight loss, bloating and severe diarrhea, admitted to the hospital in a state of dehydration. The laboratory tests revealed severe hypokalemia. Finally, vasoactive intestinal peptide (VIP) secreting ganglioneuroblastoma was diagnosed and effective surgery was performed. The second case was also a girl who suffered from the incidents of watery diarrhea and flatulence. The tumor was detected by computerized tomography scan. The 3rd stage of ganglioneuroblastoma was diagnosed. The patient required chemotherapy, radiotherapy and surgery treatment. The third child was a boy, hospitalized due to abdominal pain, constipation and weakness. During the diagnostic process, the 4th stage of neuroblastoma was recognized. The chemotherapy, surgery, radiotherapy and immunotherapy were applied. CONCLUSIONS: In children with common abdominal symptoms as chronic flatulence, diarrhea or severe constipation of unknown etiology, the neuroblastic tumors should be considered.

Severe Hyponatremia in a Single-Center Series of 84 Homogenously Treated Children With Acute Lymphoblastic Leukemia.

Electrolyte abnormalities are hallmark metabolic disturbances during the treatment of acute lymphoblastic leukemia (ALL). Hyponatremia is an ominous laboratory sign in the setting of neoplasia. We analyzed the incidence, risk factors, associations, specific interventions and outcomes of severe hyponatremia in a single-center series of children with ALL. The incidence of severe hyponatremia, defined as serum sodium levels below 130 mmol/L on at least 2 of 3 consecutive days, was 11.9%. History of hyponatremia episode is associated with neurologic complications (P=0.023) and the presence of overt central nervous system leukemia (CNS3) at diagnosis (P=0.005). Most observed hyponatremia episodes resolved relatively quickly, rarely requiring specific treatment. All but 1 hyponatremia episodes occurred in the induction or reinduction phases, but none before the administration of cytotoxic drugs, pointing to the role of therapy complications rather than leukemia per se. Most patients received vincristine shortly before hyponatremia onset, and vincristine has been previously strongly implicated in hyponatremia. We also suggest a role for imatinib. Although every patient with severe hyponatremia requires swift and thorough diagnostics a serious sequelae in the setting of pediatric ALL is rare. Hyponatremia association with neurotoxicity likely points to vincristine hypersensitivity in the subgroup of patients with both complications.

Polycomb genes expression as a predictor of poor clinical outcome in children with medulloblastoma.

INTRODUCTION: Medulloblastoma is the most frequent type of embryonal tumor in the pediatric population, accounting for 20-25% of all brain tumors in children. Recently, the suspected contribution of the Polycomb group (PcG) genes in medulloblastoma development was described. PcG genes play an important role in developmental processes; they are also involved in the self-renewal of hematopoietic and neural stem cells as well as in malignant transformation. PURPOSE: In this study, we evaluated the expression of BMI1and PCGF2, members of family of PcG genes, and their potential target, MYC oncogene, and analyzed their association with demographic and clinical data. MATERIALS AND METHODS: Thirty-one children (18 males and 13 females, aged from 0.4 to 17 years) with medulloblastoma were included in this study. The gene's expression level was measured by quantitative real-time PCR, obtained using the two-color multiplexing technique. RESULTS: We found that the higher expression levels of BMI1 and PCGF2 genes were associated with significantly decreased patient survival (p = 0.02 and p = 0.012, respectively). Significant differences between gender were found, with a higher expression level of the PCGF2 gene observed among females (p = 0.02). CONCLUSION: Our analysis showed correlation between BMI1 and PCGF2 gene's expression and survival in children with medulloblastoma.

The Broad Variability in Dental Age Observed among Childhood Survivors Is Cancer Specific.

PURPOSE: The study aimed to assess the differences in dental maturation between childhood cancer survivors and healthy children. MATERIALS AND METHODS: Fifty-nine cancer patients including 16 (27.1%) girls and 43 (72.8%) boys, aged between 4 and 16 years, underwent dental and radiographic examinations. The mean duration of anticancer therapy was 16.8 months (range, 1 to 47 months), and 4.6 years (range, 8 to 123 months) had passed since the termination of disease. The control group consisted of 177 panoramic radiographs of age- and sex-matched healthy individuals. Dental age (DA) was estimated with Demirjian's scale and delta age, i.e., DA-chronological age (CA), was used to compare groups. RESULTS: The DA of cancer survivors was accelerated by almost 1 year compared to their CA (9.9±3.1 vs. 8.9±2.8, p=0.040). The greatest difference was observed among patients with brain tumor: delta (DA-CA) was 2.2±1.1 years. Among all cancer patients, only children with familial adenomatous polyposis (FAP)-associated hepatoblastoma (HP) demonstrated delayed DA, with regard to both other cancer survivors (p=0.011) and healthy patients (p=0.037). All four patients with HP suffered from FAP, and three of them had documented adenomatous polyposis coli (APC) genes mutation. The DA of cancer patients having teeth with short roots was significantly greater than that of the cancer survivors without this anomaly (12.8±3.2 vs. 9.0±2.4, p < 0.001). CONCLUSION: DA in children may be altered by cancer disease.

Factors predicting survival in childhood malignant and intermediate vascular tumors : retrospective analysis of the Polish and German cooperative paediatric soft tissue sarcoma study groups and review of the literature.

BACKGROUND: The rarity of malignant and intermediate vascular tumors in children means that little is known about their clinical course, optimal treatment, and variables predicting survival. METHODS: A total of 32 children with malignant vascular tumors (14 angiosarcomas [AS], 5 epithelioid hemangioendotheliomas, and 13 intermediate vascular tumors, including other hemangioendotheliomas plus adult-type hemangiopericytomas), registered in the German and Polish Paediatric Soft Tissue Sarcomas Study Groups, were treated following the Cooperative Weichteilsarkom Studiengruppe (CWS)-81, -86, -91, and -96 protocols. RESULTS: Male sex, AS histology, tumor size >5 cm, and T2 invasiveness were independent predictors of inferior 5-year overall survival, while AS histology and T2 invasiveness were predictors of inferior 5-year event-free survival. AS histology was the most important negative prognostic factor for overall survival and event-free survival. Completeness of primary tumor excision was a good prognostic factor for survival in univariate, but not multivariate, analysis. Local therapy (radiotherapy and delayed surgery) were provided to the minority of patients (28% and 38%, respectively) late in the course of disease (after a mean of 9 and 6 months, respectively) and did not prevent local relapses. Response to systemic treatment was poor (44%) and did not prevent local and distant relapses. CONCLUSIONS: The clinical course and outcome in childhood epithelioid HE seems to be similar to intravascular tumors and less aggressive than AS. RTX and delayed surgery should be performed more frequently and earlier in the disease course. An urgent need for modification of systemic therapy is needed because of the development of many metastatic and/or combined relapses and poor response to classic chemotherapy. The problem of effective therapy for childhood AS is the most appaling: 13 of 14 patients died of progression despite multimodal treatment.

Pulmonary Exacerbation of Undiagnosed Toxocariasis in Intensively-Treated High-Risk Neuroblastoma Patients.

Toxocariasis is one of the most common zoonoses, with high seroprevalence in apparently healthy individuals. Neuroblastoma is an aggressive childhood cancer. The cure rates are improving due to dose-dense chemotherapy, progress in surgical practice, myeloablative therapy with autologous stem cell transplantation, and recently, anti-GD2 immunotherapy. This is associated with a burden of complications, some of which are relatively specific for neuroblastoma treatment. Based on previous reports of Toxocara canis infection in high-risk neuroblastoma patients and cases of pulmonary exacerbation from our center in this disease, we propose that toxocariasis is a specific complication of intensive pediatric cancer treatment and advocate for active surveillance.

The cross-reactivity of anti-asparaginase antibodies against different L-asparaginase preparations.

Repeated administration of L-asparaginase leads to the development of specific antibodies and hypersensitivity reactions. The aim of the study was to evaluate a possible cross-reaction of anti-asparaginase antibodies, developed against the native E. coli L-asparaginase (Asparaginase Medac), with other preparations of the enzyme. Sixteen patients with acute lymphoblastic leukemia, in whom in the reinduction phase of treatment hypersensitivity against L-asparaginase was observed and/or the presence of anti-asparaginase antibodies was established were recruited for the present study. Ten out of 16 tested sera showed cross-immunoreactivity to PEG-asparaginase, while no reactivity to L-asparaginase derived from Erwinia chrysantemi was observed. Since cross-reacting antibodies were also found in sera of patients with no overt allergic reaction, L: -asparaginase may undergo silent inactivation during the reinduction phase of therapy. This finding is of clinical importance with regard to appropriate dosage and necessitates careful enzyme activity monitoring in all patients undergoing repeated treatment with various L-asparaginase preparations.

Dynamic changes in specific anti-L-asparaginase antibodies generation during acute lymphoblastic leukemia treatment.

BACKGROUND: L-asparaginase (L-asp) remains one of the key components of acute lymphoblastic leukemia therapy. Immune reactions to the drug are associated with its diminished activity. The aim of the study was to determine the level of IgM, IgG and IgE-class anti-L-asp antibodies during the induction and reinduction phases of acute lymphoblastic leukemia therapy and their influence on L-asp activity. METHODS: The study group comprised 65 patients treated for acute lymphoblastic leukemia in one pediatric oncology center. L-asp antibodies were assessed using ELISA at the end of the induction and reinduction phases. L-asp activity was assessed prior to each drug administration by colorimetry. RESULTS: At the end of the first exposure to L-asp antibodies were detected in 35 patients (54%). In the reinduction phase of the treatment anti-L-asp antibodies were found in 38/55 patients (69%). In the induction phase patients with inadequate L-asp activity had higher IgM concentrations (median 5.88 versus 2.81 µg/mL, p = 0.03). In the reinduction phase IgG and IgM levels correlated inversely with L-asp activity. Patients with L-asp allergy had higher levels of IgG (median 61.6 versus 18.36 µg/mL, p = 0.01), whereas higher IgE levels were noted in the group of patients with inadequate drug activity (median 0.91 versus 0.64 µg/mL, p = 0.03). CONCLUSIONS: Subsequent exposure to L-asp in the treatment of acute lymphoblastic leukemia was associated with the increase of anti-L-asp antibodies in all studied classes. However, the changes observed in specific classes of antibodies were not distinctive for L-asp hypersensitivity or inactivation, suggesting that the mechanism is more complex.

Tumor expression of survivin, p53, cyclin D1, osteopontin and fibronectin in predicting the response to neo-adjuvant chemotherapy in children with advanced malignant peripheral nerve sheath tumor.

PURPOSE: Selected cell-cycle regulators and extracellular matrix proteins were found to play roles in malignant peripheral nerve sheath tumor (MPNST) biology. We aimed to analyze whether initial tumor tissue expressions of survivin, p53, cyclin D1, osteopontin (OPN) and fibronectin (FN) correlate with the response to neo-adjuvant CHT (naCHT) in children with advanced inoperable MPNST. METHODS: The study included 26 children with MPNST (M/F 14/12, median age 130 months) treated in Polish centers of pediatric oncology between 1992 and 2013. Tissue expression of markers was studied immunohistochemically in the manually performed tissue microarrays and assessed semi-quantitatively as low and high, based on the rate of positive cells and staining intensity. RESULTS: Good response to naCHT was noted in 47.6%, while poor-in 52.4% of patients. The response to naCHT was influenced negatively by the presence of neurofibromatosis NF1 and high initial tumor tissue expression of OPN, survivin, p53 and cyclin D1. Patients with high tumor expression of either OPN, survivin or p53 and those with simultaneous high expression of ≥ 3 of the markers, responded significantly worse to naCHT, than patients, in whom expression of ≤ 2 markers were detected at diagnosis. Nearly, 85% of patients expressing ≥ 3 markers, responded poor to CHT; while 87.5% of children, expressing ≤ 2 markers, were good responders. CONCLUSION: The initial tumor tissue expression of OPN, survivin, p53 and cyclin D1 may serve as markers to predict response to naCHT in pediatric advanced MPNST. Future studies in more numerous group of patients are needed to confirm these preliminary results.

The anti-asparagines antibodies correlate with L-asparagines activity and may affect clinical outcome of childhood acute lymphoblastic leukemia.

The primary aim of the study was to evaluate the importance of anti-asparaginase antibodies for l-asparaginase activity in children with standard and medium risk acute lymphoblastic leukemia (ALL). Forty-seven children with newly diagnosed ALL were included into the prospective study. Enzyme activity and the presence of anti-asparaginase antibodies (IgG and IgM class) were determined. Anti-asparaginase antibodies were identified in 13/47 (IgM class) and 10/47 (IgG class) patients in the induction and in 19/47 (IgM class) and 20/47 (IgG class) patients in the reinduction phase of treatment. The enzyme activity was lower in patients that were positive for anti-asparaginase antibodies, especially in reinduction phase (median 37 (20 - 180) vs 355 (141 - 499), p = 0.001). An association between anti-asparaginase antibodies and the allergic reaction to the drug was found. Besides, the children who developed anti-asparaginase antibodies in the induction phase of treatment showed lower event-free survival as well as overall survival in comparison with children without antibodies. Since our study was carried out in a small number of patients, this observation is only speculative and needs to be confirmed by a further study on a larger sample size, with multivariable analysis. However, our data suggest that L-asparaginase activity together with anti-asparaginase antibodies measurements may become useful for effective therapy of ALL.

[Acute lymphoblastic leukemia in a child with Sturge-Weber syndrome--case report]. / Ostra bialaczka limfoblastyczna u dziecka chorego na zespól Sturge'a-Webera--opis przypadku.

Sturge-Weber syndrome belongs to the group of neuroektomesodermal diseases, so called facomatoses. In contrast to other diseases of this group, there are not any proofs of the genetic determinated background of the syndrome, as well as the higher frequency of cancer. However, the higher frequency of benign astrocytomas was observed. The presented case of the coincidence of the Sturge-Weber syndrome and acute lymphoblastic leukemia is the second case described in the literature. The authors present the therapeutical problems, associated with glaucoma and epilepsy in the course of this syndrome.

The Role of Histone Protein Modifications and Mutations in Histone Modifiers in Pediatric B-Cell Progenitor Acute Lymphoblastic Leukemia.

While cancer has been long recognized as a disease of the genome, the importance of epigenetic mechanisms in neoplasia was acknowledged more recently. The most active epigenetic marks are DNA methylation and histone protein modifications and they are involved in basic biological phenomena in every cell. Their role in tumorigenesis is stressed by recent unbiased large-scale studies providing evidence that several epigenetic modifiers are recurrently mutated or frequently dysregulated in multiple cancers. The interest in epigenetic marks is especially due to the fact that they are potentially reversible and thus druggable. In B-cell progenitor acute lymphoblastic leukemia (BCP-ALL) there is a relative paucity of reports on the role of histone protein modifications (acetylation, methylation, phosphorylation) as compared to acute myeloid leukemia, T-cell ALL, or other hematologic cancers, and in this setting chromatin modifications are relatively less well studied and reviewed than DNA methylation. In this paper, we discuss the biomarker associations and evidence for a driver role of dysregulated global and loci-specific histone marks, as well as mutations in epigenetic modifiers in BCP-ALL. Examples of chromatin modifiers recurrently mutated/disrupted in BCP-ALL and associated with disease outcomes include MLL1, CREBBP, NSD2, and SETD2. Altered histone marks and histone modifiers and readers may play a particular role in disease chemoresistance and relapse. We also suggest that epigenetic regulation of B-cell differentiation may have parallel roles in leukemogenesis.

Biallelic loss of CDKN2A is associated with poor response to treatment in pediatric acute lymphoblastic leukemia.

The inactivation of tumor suppressor genes located within 9p21 locus (CDKN2A, CDKN2B) occurs in up to 30% of children with B-cell precursor acute lymphoblastic leukemia (BCP-ALL), but its independent prognostic significance remains controversial. In order to investigate the prognostic impact of deletions and promoter methylation within 9p21, 641 children with newly diagnosed BCP-ALL using methylation specific multiplex ligation-dependent probe amplification (MS-MLPA) were investigated. A total of 169 (26.4%) microdeletions in 9p21 were detected, of which 71 were homozygous. Patients with CDKN2A homozygous deletions were older at diagnosis (p < .001), more frequently steroid resistant (p = .049), had higher WBC count (p < .001), higher MRD at Day 15 (p = .013) and lower relapse-free survival [p = .028, hazard ratio: 2.28 (95% confidence interval: 1.09-4.76)] than patients without these alterations. CDKN2A homozygous deletions coexisted with IKZF1 and PAX5 deletions (p < .001). In conclusion, CDKN2A homozygous deletions, but not promoter methylation, are associated with poor response to treatment and increased relapse risk of pediatric BCP-ALL.

Cytoprotective effect of amifostine in the treatment of childhood neoplastic diseases--a clinical study including the pharmacoeconomic analysis.

Amifostine is an active aminothiol, which has unique properties as a radio- and chemoprotective agent. It has been reported to prevent myelosuppression and reduce the toxic effects of intensive cancer treatment. In the study, 57 courses of chemotherapy in 18 children treated because of neoplastic disease were analyzed to assess the early side effects induced by cytotoxic anticancer therapy. In 18 of them amifostine was used as the cytoprotective agent. The estimation of adverse effects was made in accordance to WHO scale of toxicity, and the pharmacoeconomic analysis was based on the costs of intravenous antibiotics, G-CSF, GM-CSF, blood preparations, immunoglobulins and days of hospitalization. The amifostine use in supportive therapy of neoplastic diseases in children decreases the number of infections thanks to the diminishing of myelotoxic effect. This not only improves the comfort of the patient but also shortens the time of hospitalization. The amifostine therapy limits the costs of treatment, but high price of the drug itself, makes however, the chemotherapy with cytoprotection comparable in pharmacoeconomic analysis to the standard treatment.

Haemophilia A and cardiovascular morbidity in a female SHAM syndrome carrier due to skewed X chromosome inactivation.

We have recently described a severe haemophilia A and moyamoya (SHAM) syndrome caused by Xq28 deletions encompassing F8 and the BRCC3 familial moyamoya gene. The phenotype includes haemophilia A, moyamoya angiopathy, dysmorphia and hypertension. The genetic analysis of the family of our SHAM patient demonstrated carrier state in proband's mother and sister. The patient's mother is apparently well, whereas his currently 18-years-old sister presents with mild haemophilia A, coarctation of the aorta, hypertension, and ventricular arrhythmia. We performed X chromosome inactivation assay based on HpaII methylation analysis of a polymorphic short tandem repeat (STR) in the X linked AR (androgen receptor) gene and used quantitative real-time RT PCR to measure the expression of genes from the deleted region in proband's family members. We found an extremely skewed X chromosome inactivation pattern in the female members of the family leading to preferential inactivation of the X chromosome without Xq28 deletion in patient's sister. We demonstrated differential expression of the genes from the deleted region in four members of the family, that tightly correlates with the clinical features. In conclusion, we show that the haematologic and cardiovascular morbidity and the discrepancy between patient's sister and mother despite the same genetic lesion are due to skewed X chromosome inactivation leading to clinically relevant differential expression of SHAM syndrome genes. This report highlights the role for BRCC3 in cardiovascular physiology and disease, and demonstrates that in some complex hereditary syndromes full diagnostics may require the examination of both genetic and epigenetic events.

A need for cautious interpretation of elevated serum germ cell tumor markers in children. Review and own experiences.

Protocols for pediatric germ cell tumors (GCT) allow for chemotherapy (CHT) initiation without histological diagnosis, based on typical clinical and radiological picture and increased alphafetoprotein (AFP) or beta-human chorionic gonadotropin serum levels. Such strategy may result in misdiagnoses in rare cases. We present two patients with abdominal tumors and high serum AFP levels, diagnosed as GCT. In both, no tumor shrinkage and increasing AFP was observed after first cycles of multidrug CHT for pediatric GCT. Histological examination of biopsied tumor tissues revealed metastatic cholangiocarcinoma in patient 1 and pancreatoblastoma in patient 2, which implicated immediate change of therapy. Presented cases support the necessity to consider the tumor biopsy when patients diagnosed with GCT based on typical clinical presentation and elevated AFP do not respond to CHT with AFP decrease and tumor size reduction.