Resistance to glucocorticoids in childhood acute lymphoblastic leukemia: impact of relationship between ex vivo sensitivity and in vivo concentration on risk factor analysis

Resistance to glucocorticoids remains one of the main obstacles in therapy of childhood acute lymphoblastic leukemia (ALL). The aim of the study was the analysis of relationship between ex vivo drug resistance of prednisolone and dexamethasone and exposure to these drugs in childhood ALL, with respect to risk factor analysis. Ex vivo resistance to both glucocorticoids was compared to maximum drug concentration achievable in body fluids, calculated in mathematical model. Drug resistance to vincristine and L-asparaginase, expression of multidrug resistance and apoptosis proteins was also determined. Concentration of both glucocorticoids in extracellular fluid was higher than drug resistance in the following groups of patients: in initial ALL patients, in patients staying in remission during follow-up, and in prednisolone good responders. Factors significant by multivariate analysis were early bone marrow response by day 15 and concentration of prednisolone higher than ex vivo prednisolone resistance. For initial ALL patients with determined response to initial prednisolone monotherapy, factors significant by univariate analysis were early bone marrow response, and exposure to glucocorticoids higher than ex vivo resistance to these drugs. No factor was significant by multivariate analysis in this group. Risk factor analysis showed that concentration of prednisolone and dexamethasone higher than respective ex vivo drug resistance, is a strongest prognostic factor in childhood ALL.

Anti-HBs profiles in children treated for neoplastic disease who had been vaccinated against hepatitis B postnatally or as infants

Children with cancer are a risk group for hepatitis B virus (HBV) infection. In Poland, the initiation of a national HBV vaccination programme in neonates and infants in 1995 has contributed to the prevention of HBV infection in children treated for neoplastic diseases. The objective of this study was to analyse the anti-HBs pattern and occurrence of HBV infections in children with cancer who had been vaccinated during infancy. The study included 96 children divided into three groups: Group A, children who had received a full vaccination course with an initial level of anti-HBs >/=100 IU/L; Group B, children who had received a full vaccination course with anti-HBs <100 IU/L, for whom an additional dose of vaccine was administered; and Group C, children who had further immunoprophylaxis because they did not complete the vaccination course before cancer diagnosis. A protective level of anti-HBs after the full vaccination programme was found in 80.5% of children after three months, 74.2% after six months, 61.5% after 12 months and 78.6% after 18 months. Among children who produced antibodies, a slow decrease in the level of anti-HBs was observed. It was still protective during follow-up in Group A, but occasionally fell below 100 IU/L in Group B. In Group C, five of 11 subjects had a protective level of anti-HBs throughout follow-up. Of 28 children who showed the presence of HBsAg during follow-up, 23 eradicated the virus. In children with cancer vaccinated against HBV according to the vaccination schedule, the immune response maintains a protective level of anti-HBs in more than 60% of cases, despite immunosuppression.

Differential chemosensitivity in a child with congenital relapsing acute lymphoblastic leukemia

Described is a case of a boy with congenital acute lymphoblastic leukemia (ALL) with pre-pre-B-ALL immunophenotype, presenting as diarrhea, organomegaly, hyperleucocytosis of 1434 G/L, and tumor lysis syndrome. The lymphoblasts showed low proliferative activity and high in vitro drug sensitivity measured by the MTT assay. An excellent response to therapy was observed, but relapse ocurred 3 months later. On relapse, blasts showed extremely high drug resistance, high expression of P-glycoprotein, and high proliferative activity. The response to therapy was again positive, but a second relapse occurred in 1 month. The MTT assay indicated increasing drug resistance to all drugs. Cytogenetic analysis revealed deletion in 11q23 locus. This unfavorable case shows complex biology and differential drug resistance in congenital leukemia.