Use of Lymphoid Progenitor Cell Assays for a More Detailed Analysis of the Cytogenetic Changes Occurring During Clonal Evolution in Acute Lymphoblastic Leukemia

Differential effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF) on the radiation sensitivity of normal versus leukemic bone marrow progenitor cell populations

We examined the effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF), interleukin 3 (rhIL-3) and interleukin 6 (rhIL-6) on the radiation sensitivity of normal and leukemic bone marrow progenitor cell populations. Conditioning of leukemic progenitor cells (LPC) from acute lymphoblastic leukemia (ALL) patients with rhG-CSF enhanced their radiation sensitivity, whereas conditioning with rhIL-3 or rhIL-6 had the opposite effect. In contrast to its effects on LPC derived from ALL patients, rhG-CSF reduced the radiation sensitivity of normal myeloid progenitor cells as well as LPC from acute myeloblastic leukemia (AML) patients. Differential modulation of the radiation sensitivity of LPC by rhG-CSF may provide the basis for better total body irradiation (TBI) regimens for ALL patients undergoing autologous bone marrow transplantation (BMT).

Sensitivity of primary clonogenic blasts from acute lymphoblastic leukemia patients to an activated cyclophosphamide, viz., mafosfamide

Primary cyclophosphamide-naive clonogenic blasts from 32 patients with newly diagnosed acute lymphoblastic leukemia (ALL) were tested for their in vitro sensitivity to an "activated" cyclophosphamide, viz., mafosfamide, using leukemic progenitor cell (LPC) colony assays. Marked interpatient variation in the responses of LPC from newly diagnosed patients to mafosfamide prompted assessment of mafosfamide sensitivity in relation to more frequently measured parameters of newly diagnosed ALL. Only immunophenotype and sex showed a significant association with the intrinsic mafosfamide sensitivity of LPC. LPC from T-lineage ALL patients were more resistant to mafosfamide than LPC from B-lineage ALL patients, as reflected by 1.8-fold and 4.3-fold higher mean SF10 and SF20 (surviving fractions of ALL LPC of 10 and 20 microM mafosfamide, respectively) values. LPC from male patients were more resistant to mafosfamide than LPC from female patients, as reflected by 1.9-fold and 4.8-fold higher mean SF10 and SF20 values. In comparison to T-lineage ALL patients, a significantly greater fraction of B-lineage ALL patients had mafosfamide-sensitive LPC with SF10 values of < 0.25 (61% vs 11%, P = 0.01). Notably, all four cases exhibiting resistance to mafosfamide, i.e., SF20 > or = 0.5, were males with T-lineage ALL. In order to exclude the influence of sex as a confounding factor in the observed immunophenotype-mafosfamide sensitivity association, we also compared the mafosfamide sensitivities of LPC from male patients only. The means of SF10, and SF20 values of LPC from male T-lineage ALL patients were 1.5- and 3.2-fold higher than those of LPC from male B-lineage ALL patients (P < 0.1). Thus, in the male patient subgroup, the immunophenotype-mafosfamide sensitivity association remained significant.

Radiation resistance of primary clonogenic blasts from children with acute lymphoblastic leukemia

PURPOSE

Detailed comparative analyses of the radiation sensitivity of primary clonogenic blasts from children with acute lymphoblastic leukemia (ALL) were performed to achieve a better understanding of clinical radiation resistance in ALL.

METHODS AND MATERIALS

The radiation sensitivity of primary clonogenic blasts from 74 children with newly diagnosed acute lymphoblastic leukemia (ALL) was analyzed using leukemic progenitor cell (LPC) assays. Primary bone marrow blasts from all 74 patients were exposed to ionizing radiation and subsequently assayed for LPC-derived blast colony formation. Radiation survival curves of primary clonogenic blasts (i.e., LPC) were constructed for each of the newly diagnosed patients using computer programs for the single-hit multitarget as well as the linear quadratic models of cell survival.

RESULTS

A marked interpatient variation in intrinsic radiation sensitivity was observed between LPC populations. The SF2 values ranged from 0.01 to 1.00 (median: 0.36; mean +/- SE = 0.40 +/- 0.03), and the alpha values ranged from 0.00 Gy-1 to 3.27 Gy-1 (median: 0.280 Gy-1; mean +/- SE = 0.43 +/- 0.09 Gy-1). Patients were divided into groups according to their sex, age, WBC at diagnosis, cell cycle distribution of leukemic blasts, and immunophenotype. Only immunophenotype provided a significant correlation with the intrinsic radiation sensitivity of LPC. Patients with B-lineage ALL had higher SF2 (0.47 +/- 0.04 vs. 0.31 +/- 0.05, p < 0.05) and smaller alpha values (0.43 +/- 0.09 Gy-1 vs. 0.65 +/- 0.10 Gy-1, p < 0.05) than T-lineage ALL patients, consistent with greater intrinsic radiation resistance at the level of LPC. Notably, 43% of B-lineage ALL cases, but only 27% of T-lineage ALL cases had LPC with SF2 > or = 0.5. Similarly, 66% of B-lineage ALL cases, but only 37% of T-lineage ALL cases had LPC with alpha values < or = 0.4 Gy-1. Combining the two indicators of radiation resistance, we found that only 34% of the B-lineage ALL patients had none of the two parameters in the respective critical regions (alpha < or = 0.4 Gy-1; SF2 > or = 0.5), while 63% of the T-lineage patients had none (p < 0.05). In multivariate analyses, the immunophenotypic B-lineage affiliation was the only significant predictor of radiation resistance at the level of LPC. Whether alone or in combination, none of the other variables examined, including sex, age, WBC, in vitro plating efficiency, S-phase index, and proliferation index were significantly correlated with the radiation sensitivity or resistance of LPC.

CONCLUSION

These results offer unprecedented evidence for an association between composite immunophenotype (viz., B-lineage ALL vs T-lineage ALL) and radiation resistance that may form a basis for modifying radiation conditioning regimens.

Immunophenotype predicts radiation resistance in T-lineage acute lymphoblastic leukemia and T-lineage non-Hodgkin's lymphoma

In the preclinical arm of our study, the radiobiologic features of primary malignant cells from newly diagnosed and relapsed T-lineage acute lymphoblastic leukemia/non-Hodgkin's lymphoma patients were analyzed using clonogenic assays. A marked heterogeneity existed relative to the intrinsic radiation sensitivity of clonogenic T-lineage ALL/NHL cells from 42 patients. The mean SF2 (surviving fraction at 200 cGy) and alpha values (initial slope of the survival curve) were 0.36 +/- 0.04, and 0.558 +/- 0.079 Gy-1. Fourteen cases had SF2 values of > or = 0.50 and alpha values of < or = 0.2 Gy-1, consistent with a marked intrinsic radiation resistance at the level of clonogenic leukemia/lymphoma cells. Of these 14 radiation resistant cases, 12 were CD3+. Furthermore, the SF2 and D0 values of the 28 CD3+ cases were significantly higher than the SF2 and D0 values of the 14 CD3- cases (SF2: 0.441 +/- 0.048 versus 0.189 +/- 0.045, p = 0.002; D0: 189.6 +/- 26.3 cGy versus 108.7 +/- 18.2 cGy, p = 0.047) and CD3+ cases had smaller alpha values than CD3- cases (0.454 +/- 0.087 versus 0.765 +/- 0.152, p = 0.06). Thus, clonogenic cells from CD3+ T-lineage ALL/NHL patients were more resistant to radiation than clonogenic cells from CD3- T-lineage ALL/NHL patients. In the clinical arm of our study, 33 T-lineage ALL/NHL patients received autologous bone marrow transplants during remission. Pretransplant conditioning consisted of total body irradiation combined with high dose chemotherapy. The expression of CD3 antigen predicted the outcome of relapsed T-lineage ALL/NHL patients undergoing autologous bone marrow transplantation following total body irradiation plus high dose chemotherapy. Overall, the Kaplan-Meier estimate and standard error of the probability of remaining in remission at 3.5 years was 11 +/- 9% with a median relapse-free interval of 102 days. The disease-free survival at 3.5 years was 8 +/- 7% with a median disease-free survival time of 96 days. Notably, the expression of CD3 antigen on T-lineage ALL/NHL cells correlated with the probability of relapse after bone marrow transplantation. While 16 of 19 CD3+ patients relapsed after bone marrow transplantation, only 3 of 8 CD3- patients relapsed. The Kaplan-Meier estimates and standard errors of the probability of remaining in remission at 1 year after bone marrow transplantation were 7 +/- 6% (median relapse-free interval = 74 days) for CD3+ patients (n = 19) and 63 +/- 17% for CD3- patients (n = 8) (p = 0.006).(ABSTRACT TRUNCATED AT 400 WORDS)