Acute lymphocytic leukemia: a comprehensive review with emphasis on biology and therapy

In vitro culture of human acute lymphoblastic leukemia (ALL) cells in serum-free media; a comparison of native ALL blasts, ALL cell lines and virus-transformed B cell lines

The aim of this study was to standardize in vitro culture conditions for human acute lymphoblastic leukemia (ALL) cells. The cells were cultured in medium containing 10% fetal calf serum (FCS) and in the four serum-free media X-vivo 10, X-vivo 15, X-vivo 20 and Stem Span. Native ALL blasts could proliferate in all four serum-free media, but the strongest responses were usually observed with Stem Span. Native leukemia blasts were also cultured in the presence of various single cytokines or cytokine combinations. The highest proliferation was usually observed in the presence of Flt3-Ligand (Flt3-L) when single cytokines were examined, and these responses could be further increased especially by combining Flt3-L with interleukin 3 (IL3), IL7 or stem cell factor (SCF). Proliferation could also be increased when ALL blasts were cultured in the presence of two commercially available fibroblast cell lines (Hs27 and HFL1). Based on these results we suggest that in vitro culture conditions for native human ALL blasts can be standardized by using serum-free culture media supplemented with exogenous Flt3-L+IL3+SCF, and the use of accessory cells can also be standardized by using well-characterized fibroblast cell lines. Detectable ALL blast proliferation can then be observed for most patients. Our experimental model can thereby be used for in vitro evaluation of possible antileukemic treatment strategies, and it will then allow comparison of experimental results between different studies.

Human acute lymphoblastic leukemia (ALL) blasts as accessory cells during T-cell activation: differences between patients in costimulatory capacity affect proliferative responsiveness and cytokine release by activated T cells

The ability of acute lymphoblastic leukemia (ALL) blasts to mediate costimulatory signals during T-lymphocyte activation was investigated in an experimental model in which monoclonal T-cell populations were stimulated with standardized activation signals (anti-CD3 and anti-CD28 monoclonal antibodies; phytohemagglutinin, PHA). Leukemia cells from 12 consecutive ALL patients with high peripheral blood blast counts were studied. Proliferative T-cell responses were detected for a majority of these patients when irradiated leukemia blasts were used as accessory cells during activation. T-cell cytokine release was also observed for most patients when using nonirradiated ALL accessory cells. Low or undetectable cytokine levels were usually observed for CD8+ clones, whereas the CD4+ clones often showed a broad cytokine response with release of interleukin-2 (IL-2), IL-4, IL-10, IL-13 and interferon gamma(IFN-gamma) in the presence of the ALL accessory cells. ALL blasts were also able to function as allostimulatory cells for normal peripheral blood mononuclear responder cells. However, both T-cell proliferation and cytokine release showed a wide variation between ALL patients. The accessory cell function of ALL blasts showed no correlation with the release of immunomodulatory mediators (IL-2, IL-10, IL-15) or the expression of any single adhesion/costimulatory membrane molecule (CD54, CD58, CD80, CD86) by the blasts. We conclude that for a majority of patients, native ALL blasts can mediate costimulatory signals needed for accessory cell-dependent T-cell activation, but differences in costimulatory capacity between ALL patients affects both the proliferative responsiveness and cytokine release by activated T cells.

Phase I study of irofulven (MGI 114), an acylfulvene illudin analog, in patients with acute leukemia

Irofulven (MGI 114, 6-hydroxymethylacylfulvene, HMAF) is a semisynthetic illudin analog with broad in vitro anti-neoplastic activity. In this leukemia phase I study, we investigated the toxicity profile and activity of Irofulven in patients with primary refractory or relapsed acute myeloid leukemia (AML), acute lymphocytic leukemia (ALL), or myelodysplastic syndromes (MDS). Irofulven was given as an intravenous infusion over five minutes daily for five days. The starting dose was 10 mg/m2/day (50 mg/m2/course). Courses were scheduled to be given every 3-4 weeks according to toxicity and antileukemic efficacy. Twenty patients [AML: 17 patients; MDS: one patient; ALL: one patient; mixed lineage acute leukemia: one patient] were treated. Nausea, vomiting, hepatic dysfunction, weakness, renal dysfunction, and pulmonary edema were dose limiting toxicities, occurring in two of five patients treated at 20 mg/m2/day and two of three patients treated at 12.5 mg/m2/day. The MTD was defined as 10 mg/m2/day for five days. One patient with primary resistant AML achieved complete remission. Proposed phase II studies will further define the activity of Irofulven in patients with better prognosis AML and in other hematological malignancies, both as a single agent and in combination regimens, particularly with topoisomerase 1 inhibitors.

Troxacitabine, a novel dioxolane nucleoside analog, has activity in patients with advanced leukemia

PURPOSE

To investigate the toxicity profile, activity, and pharmacokinetics of a novel L-nucleoside analog, troxacitabine (BCH-4556), in patients with advanced leukemia.

PATIENTS AND METHODS

Patients with refractory or relapsed acute myeloid (AML) or lymphocytic (ALL) leukemia, myelodysplastic syndromes (MDS), or chronic myelogenous leukemia in blastic phase (CML-BP). Troxacitabine was given as an intravenous infusion over 30 minutes daily for 5 days. The starting dose was 0.72 mg/m(2)/d (3.6 mg/m(2)/course). Courses were given every 3 to 4 weeks according to toxicity and antileukemic efficacy. The dose was escalated by 50% until grade 2 toxicity was observed, and then by 30% to 35% until the dose-limiting toxicity (DLT) was defined.

RESULTS

Forty-two patients (AML: 31 patients; MDS: six patients [five MDS + one CMML]; ALL: four patients; CML-BP: one patient) were treated. Median age was 61 years (range, 23 to 79 years), and 29 patients were males. Stomatitis and hand-foot syndrome were the DLTs. The MTD was defined as 8 mg/m(2)/d. The pharmacokinetic behavior of troxacitabine is linear over the dose range of 0.72 to 10.0 m/m(2). Approximately 69% of troxacitabine was excreted as unchanged drug in the urine. Marrow hypoplasia occurred between days 14 and 28 in 73% of AML patients. Three complete remissions and one partial remission were observed in 30 assessable AML patients. One MDS patient achieved a hematologic improvement. A patient with CML-BP achieved a return to chronic phase disease.

CONCLUSION

Troxacitabine has a unique metabolic and pharmacokinetic profile and significant antileukemic activity. DLTs were stomatitis and hand-foot syndrome. Troxacitabine merits further study in hematologic malignancies.

ATM gene deletion in patients with adult acute lymphoblastic leukemia

BACKGROUND

Loss of heterozygosity (LOH) at the ATM gene (mutated in ataxia telangiectasia [AT] patients) and ATM protein deficiency occur in 14% and 34%, respectively, of patients with chronic lymphocytic leukemia (CLL). ATM protein deficiency also is associated with aggressive disease and worse patient survival. Considering the aberrations in the ATM gene in CLL and the high rate of incidence of lymphoid neoplasias in AT patients, the authors investigated its incidence rate and significance in patients with adult acute lymphoblastic leukemia (ALL).

METHODS

Samples from 36 adults with ALL were analyzed for LOH and homozygous deletion (HD) using a panel of three microsatellite markers located at the ATM gene (D11S2179), the MLL gene (D11S1356), and the BCL1 gene (D11S987) loci. These markers are located within the 11q13-q23 locus.

RESULTS

Of the 36 informative cases, 10 (28%) showed deletions (7 LOH and 3 HDs) at the D11S2179 marker. In two patients, the deletions were extended to the MLL gene locus. These deletions were submicroscopic because only 3% (1 of 36) of patients showed abnormalities involving 11q23 using cytogenetic studies. The authors also estimated the levels of ATM protein in 15 ALL patients and 12 healthy volunteers by radioimmunoassay. The ATM protein levels in cases with LOH at the ATM gene were between 15-50% of those from normal bone marrow. In contrast to CLL patients, patients with LOH or HD at the ATM gene locus showed better survival compared with patients without ATM gene deletions (P = 0.003).

CONCLUSIONS

LOH of the ATM gene and protein deficiency are common in adult ALL, are not demonstrated at the cytogenetic level, and are associated with a favorable prognosis. The authors speculate that ATM deficiency may increase the sensitivity of leukemic blasts to the chemotherapy used during induction and after disease remission in patients with adult ALL. The relatively high frequency of deletion of the D11S2179 marker compared with the D11S1356 marker suggests that ATM is the target gene of the deletion at the 11q23 locus, and that such deletions may play a role in the pathogenesis of ALL.