ALBERT

Description: Leukemic blasts from 774 children with newly diagnosed acute lymphocytic leukemia (ALL) have been phenotyped by microcytotoxicity testing with a panel of monoclonal antibodies and heteroantisera as part of a Pediatric Oncology Group classification study of acute leukemia. One hundred twenty-two cases, or 16% were designated as T cell leukemia based on the reactivity of blast cells with previously well-characterized antisera (PT) against a T lymphocyte-associated antigen. Using this antisera-based definition as a standard, we looked for a monoclonal antibody combination that would be a suitable substitute. An algorithm calling for reactivity with either monoclonal antibody 3A1 or Leu-1 was a 92% sensitive and 97% specific predictor of PT reactivity. Only 27 of 755 cases of leukemia were incorrectly classified using this algorithm. Subsequently, Ficoll-Hypaque-separated bone marrow cells from 118 additional patients with ALL (21 of whom had T cell ALL) were stained by immunofluorescence using a combination of directly fluoresceinated 3A1 and Leu-1. Reactivity of 20% or more of the cells with this antibody combination was a 100% sensitive and 94% specific indicator of T cell ALL defined by PT positivity; with a higher cutoff value for positive values, or the use of supplemental tests, even this small number of false-positives could be eliminated. We conclude that this monoclonal antibody combination is a satisfactory replacement for our heteroantisera definition of T cell ALL.

Description: Leukemic blasts from 774 children with newly diagnosed acute lymphocytic leukemia (ALL) have been phenotyped by microcytotoxicity testing with a panel of monoclonal antibodies and heteroantisera as part of a Pediatric Oncology Group classification study of acute leukemia. One hundred twenty-two cases, or 16% were designated as T cell leukemia based on the reactivity of blast cells with previously well-characterized antisera (PT) against a T lymphocyte-associated antigen. Using this antisera-based definition as a standard, we looked for a monoclonal antibody combination that would be a suitable substitute. An algorithm calling for reactivity with either monoclonal antibody 3A1 or Leu-1 was a 92% sensitive and 97% specific predictor of PT reactivity. Only 27 of 755 cases of leukemia were incorrectly classified using this algorithm. Subsequently, Ficoll-Hypaque-separated bone marrow cells from 118 additional patients with ALL (21 of whom had T cell ALL) were stained by immunofluorescence using a combination of directly fluoresceinated 3A1 and Leu-1. Reactivity of 20% or more of the cells with this antibody combination was a 100% sensitive and 94% specific indicator of T cell ALL defined by PT positivity; with a higher cutoff value for positive values, or the use of supplemental tests, even this small number of false-positives could be eliminated. We conclude that this monoclonal antibody combination is a satisfactory replacement for our heteroantisera definition of T cell ALL.

Description: Two hundred fifty-three children with newly diagnosed T-cell acute lymphoblastic leukemia (ALL), who were treated uniformly with modified LSA2L2 therapy, were evaluated using univariate and recursive partition analyses to define clinical or biologic features associated with risk of treatment failure. Overall event-free survival (EFS) at 4 years was 43% (SE = 4%). Factors examined included white blood cell (WBC) level, age, gender, race (black v other), presence of a mediastinal mass, hepatomegaly, splenomegaly, marked lymphadenopathy, hemoglobin level, platelet count, blast cell expression of antigens such as the common acute lymphoblastic leukemia antigen (CALLA, CD10), HLA-DR, and T-cell- associated antigens (CD3, CD4, CD8, CD7, CD5, and THY). Univariate analysis showed that age less than or equal to 5 or less than or equal to 7 years, WBC level less than 10, less than 25, less than 50 or less than 100 x 10(3)/microL, and blast cell expression of CD4, CD8, or CALLA were associated with significantly better EFS, while hepatomegaly and splenomegaly were associated with worse EFS. Recursive partitioning analysis showed that the most important single favorable prognostic factor was a WBC level less than 50 x 10(3)/microL and, for patients with WBC counts below this level, the most important predictor of EFS was blast cell expression of the pan-T antigen defined by the monoclonal antibody (MoAb), L17F12 (CD5). For patients with higher WBC levels, the most important predictor of EFS was blast cell expression of THY antigen. The recursive partitioning analysis defined three groups of patients with widely varied prognoses identified as follows: (1) those with a WBC count less than 50 x 10(3)/microL who lacked massive splenomegaly and had blasts expressing CD5 had the best prognosis (66%, SE = 7%, EFS 4 years, n = 84); (2) those with (b1) WBC counts less than 50 x 10(3)/microL with either massive splenomegaly or who had blasts lacking CD5 expression, or (b2) WBC counts greater than 50 x 10(3)/microL with expression of the THY antigen had an intermediate prognosis (39%, SE = 7% EFS at 4 years, n = 94); (3) those with WBC counts greater than 50 x 10(3)/microL and whose blasts lacked expression of THY antigen had the poorest outcome (EFS = 19% at 4 years, SE = 8%, n = 63). A three-way comparison of EFS according to these groupings showed significant differences among the three patient groups (P less than .001). The recursive partitioning was able to classify 241 (95%) of the patients.(ABSTRACT TRUNCATED AT 400 WORDS)

Description: Two hundred fifty-three children with newly diagnosed T-cell acute lymphoblastic leukemia (ALL), who were treated uniformly with modified LSA2L2 therapy, were evaluated using univariate and recursive partition analyses to define clinical or biologic features associated with risk of treatment failure. Overall event-free survival (EFS) at 4 years was 43% (SE = 4%). Factors examined included white blood cell (WBC) level, age, gender, race (black v other), presence of a mediastinal mass, hepatomegaly, splenomegaly, marked lymphadenopathy, hemoglobin level, platelet count, blast cell expression of antigens such as the common acute lymphoblastic leukemia antigen (CALLA, CD10), HLA-DR, and T-cell- associated antigens (CD3, CD4, CD8, CD7, CD5, and THY). Univariate analysis showed that age less than or equal to 5 or less than or equal to 7 years, WBC level less than 10, less than 25, less than 50 or less than 100 x 10(3)/microL, and blast cell expression of CD4, CD8, or CALLA were associated with significantly better EFS, while hepatomegaly and splenomegaly were associated with worse EFS. Recursive partitioning analysis showed that the most important single favorable prognostic factor was a WBC level less than 50 x 10(3)/microL and, for patients with WBC counts below this level, the most important predictor of EFS was blast cell expression of the pan-T antigen defined by the monoclonal antibody (MoAb), L17F12 (CD5). For patients with higher WBC levels, the most important predictor of EFS was blast cell expression of THY antigen. The recursive partitioning analysis defined three groups of patients with widely varied prognoses identified as follows: (1) those with a WBC count less than 50 x 10(3)/microL who lacked massive splenomegaly and had blasts expressing CD5 had the best prognosis (66%, SE = 7%, EFS 4 years, n = 84); (2) those with (b1) WBC counts less than 50 x 10(3)/microL with either massive splenomegaly or who had blasts lacking CD5 expression, or (b2) WBC counts greater than 50 x 10(3)/microL with expression of the THY antigen had an intermediate prognosis (39%, SE = 7% EFS at 4 years, n = 94); (3) those with WBC counts greater than 50 x 10(3)/microL and whose blasts lacked expression of THY antigen had the poorest outcome (EFS = 19% at 4 years, SE = 8%, n = 63). A three-way comparison of EFS according to these groupings showed significant differences among the three patient groups (P less than .001). The recursive partitioning was able to classify 241 (95%) of the patients.(ABSTRACT TRUNCATED AT 400 WORDS)