Post-remission therapy of adult acute myeloid leukaemia: one cycle of high-dose versus standard-dose cytarabine. Leukaemia Project Group of the Swiss Group for Clinical Cancer Research (SAKK)

BACKGROUND

Intensification of post-remission therapy improves the cure rate of acute myeloid leukemia (AML) but is often accompanied by unacceptable toxicity. From 1985 to 1992 the Swiss Group for Clinical Cancer Research (SAKK) performed a randomized phase III trial to evaluate the effectiveness of one single postremission course of high-dose cytarabine (HDAC) in terms of leukaemia-free and overall survival in adults with de novo AML.

PATIENTS AND METHODS

Adult (15-65 years) AML patients in remission after two induction courses were randomly assigned to one consolidation course either with standard (SDAC: 100 mg/sqm 24 hours infusion over seven days) or with high-dose cytarabine (HDAC: 3000 mg/sqm every 12 hours as one-hour-infusion for six days). In addition, both arms included daunorubicin (45 mg/sqm daily on days 1 to 3). Thereafter, patients were observed without maintenance until relapse.

RESULTS

After two induction courses 208/276 eligible patients achieved remission (CR: 169, 61%, PR: 39, 14%), 41 were resistant (15%) and 20 died early (7%). Seventy-one patients in remission were not randomized. One hundred thirty-seven were randomized in CR/PR (67 SDAC, 70 HDAC). 4/70 patients randomized to HDAC did not receive it. Treatment-related mortality in HDAC was 1.4% (1/66). WHO grade 3-4 toxicities occurred in 14/67 SDAC and in 38/66 HDAC patients (P < 0.0001). The median event free survival was 10.8 (SDAC) vs. 12.2 months (HDAC; P = 0.18). The median overall survival was 24.6 (SDAC) vs. 32.6 months (HDAC; P = 0.07). Although statistically uncertain, HDAC reduced the hazard of progression (hazard ratio: 0.69, P = 0.08) and of death (hazard ratio: 0.70, P = 0.13). For 112 patients stratified as CR the estimated four-year disease-free survival was 25% (+/-6%) with SDAC and 37% (+/-6%) with HDAC (P = 0.09). The overall survival rates at four years were 38% (+7%) and 48% (+7%), respectively (P = 0.10). In multivariate analysis HDAC significantly reduced the hazard of relapse by 39% compared to SDAC (hazard ratio = 0.61, 95% CI: 0.37-0.99; P = 0.049).

CONCLUSIONS

We conclude that early consolidation of adult AML in CR with a single course of HDAC is superior in terms of outcome to one cycle of SDAC. The results of our intensive, single course HDAC group compare favourably with less intensive, repetitive HDAC cycles, suggesting that Ara-C dose intensity may be more important than total dosage. In addition, our treatment strategy is much less toxic and less expensive.

CD11b/CD18 expression, adherence, and chemotaxis of granulocyte in adult respiratory distress syndrome

The accumulation of granulocytes in the pulmonary microvasculature is generally thought a cardinal event in the pathology of adult respiratory distress syndrome (ARDS). However, the mechanism by which granulocytes are sequestered in the pulmonary vascular bed remains largely unknown. Because the CD11b/CD18 membrane receptors mediate various adhesion-dependent functions, their expression was investigated in granulocytes from patients during the course of ARDS development in relation to adherence and chemotaxis. CD11b expression of ARDS resting granulocytes was increased within 24 h of ARDS onset by a factor of two in comparison with control patients (p < 0.05) and remained significantly increased 72 to 120 h later. In contrast, the stimulated expression was significantly decreased only within 24 h of ARDS onset. Adherence was not modified within 8 h of the onset of ARDS, but was increased at Days 1, 3, and 5. The time course of granulocyte chemotaxis shows a decreased chemotaxis capacity during the first 3 d of ARDS, followed by normalization at Day 5. The dynamic changes observed in the various functions studied indicate a possible relationship between the modulation of the CD11b expression and a hyperadhesive state of granulocytes in ARDS. These sticky granulocytes may potentially contribute to the microvascular injury.

Comparison of the immunosuppressive properties of milk growth factor and transforming growth factors beta 1 and beta 2

The effects of the newly isolated bovine milk growth factor (MGF) which shows N-terminal homology to transforming growth factor beta 2 were compared with the effects of porcine transforming growth factor beta 1 and beta 2 (pTGF-beta 1 and -beta 2) on human T lymphocyte activation. Freshly isolated human PBMC were stimulated with either PHA, anti-CD3 + phorbol-12,13-dibutyrate (PDBu), or with a combination of ionomycin + PDBu. MGF, pTGF-beta 1, and pTGF-beta 2 decreased mitogen-induced [3H]thymidine incorporation by 30 to 75% in a dose-dependent manner. The maximum degree of inhibition was obtained at 1 ng/ml (40 pM) and could not be increased by increasing the concentration of teh transforming growth factor 10-fold. Stimulation of fresh T cells with the recall Ag tetanus toxoid was also inhibited (85%) by MGF at pM concentrations as was the proliferation of a human T cell clone specific for purified protein derivative. The effects of MGF and pTGF-beta 1 on anti-CD3-mediated increase of intracellular Ca2+ (Cai2+) was investigated by using the Fura-2 method. Neither MGF nor pTGF-beta 1 inhibited this increase in Cai2+ induced by a mitogenic concentration of anti-CD3 antibody. In order to determine whether TGF-beta preferentially inhibited the CD4+ or CD8+ subpopulation of human T cells, a limiting dilution analysis system, which allows every T cell to proliferate, was used. pTGF-beta 1 at a concentration of 5 ng/ml decreased the frequency of proliferating T cell precursors of both the CD4+ and CD8+ subsets to a similar extent. Furthermore, MGF, pTGF-beta 1, and pTGF-beta 2 also decreased IL-2 mediated [3H]thymidine incorporation into human PBL Con A blasts and the IL-4-mediated [3H]thymidine incorporation of purified T lymphocytes costimulated with PDBu by 70%. In conclusion, bovine MGF exerts suppressive effects on human T cells stimulated with Ag, mitogens, or interleukins, and the degree of T cell suppression is similar (or identical) to those of pTGF-beta 1 or -beta 2.

Comparison of the immunosuppressive properties of milk growth factor and transforming growth factors beta 1 and beta 2

The effects of the newly isolated bovine milk growth factor (MGF) which shows N-terminal homology to transforming growth factor beta 2 were compared with the effects of porcine transforming growth factor beta 1 and beta 2 (pTGF-beta 1 and -beta 2) on human T lymphocyte activation. Freshly isolated human PBMC were stimulated with either PHA, anti-CD3 + phorbol-12,13-dibutyrate (PDBu), or with a combination of ionomycin + PDBu. MGF, pTGF-beta 1, and pTGF-beta 2 decreased mitogen-induced [3H]thymidine incorporation by 30 to 75% in a dose-dependent manner. The maximum degree of inhibition was obtained at 1 ng/ml (40 pM) and could not be increased by increasing the concentration of teh transforming growth factor 10-fold. Stimulation of fresh T cells with the recall Ag tetanus toxoid was also inhibited (85%) by MGF at pM concentrations as was the proliferation of a human T cell clone specific for purified protein derivative. The effects of MGF and pTGF-beta 1 on anti-CD3-mediated increase of intracellular Ca2+ (Cai2+) was investigated by using the Fura-2 method. Neither MGF nor pTGF-beta 1 inhibited this increase in Cai2+ induced by a mitogenic concentration of anti-CD3 antibody. In order to determine whether TGF-beta preferentially inhibited the CD4+ or CD8+ subpopulation of human T cells, a limiting dilution analysis system, which allows every T cell to proliferate, was used. pTGF-beta 1 at a concentration of 5 ng/ml decreased the frequency of proliferating T cell precursors of both the CD4+ and CD8+ subsets to a similar extent. Furthermore, MGF, pTGF-beta 1, and pTGF-beta 2 also decreased IL-2 mediated [3H]thymidine incorporation into human PBL Con A blasts and the IL-4-mediated [3H]thymidine incorporation of purified T lymphocytes costimulated with PDBu by 70%. In conclusion, bovine MGF exerts suppressive effects on human T cells stimulated with Ag, mitogens, or interleukins, and the degree of T cell suppression is similar (or identical) to those of pTGF-beta 1 or -beta 2.

Transforming growth factors beta slow down cell-cycle progression in a murine interleukin-2 dependent T-cell line

Transforming growth factors beta (TGF-beta) inhibit the growth of a variety of cell types, including lymphocytes. The immunosuppressive effects of TGF-beta have been attributed to the interference of these molecules with the interleukin-2 (IL-2)-driven component of lymphocyte proliferation. In order to elucidate in more detail the effects of TGF-beta on IL-2-induced proliferation, we investigated the effects of porcine transforming growth factor beta 1 and 2 (pTGF-beta 1 and 2) on the IL-2-driven proliferation of a murine IL-2-dependent T-lymphocyte line (CTLL). The results showed that pTGF-beta 1 and 2 decreased 3H-thymidine incorporation in CTLL cells in a dose-dependent fashion (maximum decrease of 75-85%). Combined-time kinetic analysis of the effects of pTGF-beta on 3H-thymidine incorporation, cell growth, and cell-cycle distribution (monitored as DNA content distribution) revealed that, in the first 48 h of culture, pTGF-beta 1 increased the doubling time from 11.4 to 19.2 h without significantly affecting the cell-cycle distribution of CTLL cells. After 96 h of culture in the presence of pTGF-beta 1, cells started to accumulate in G0/G1, although at this time point 30% of the pTGF-beta 1-treated cells were still in S-G2/M. Furthermore, during the first 48 h, neither the expression of the 55 kd chain of the IL-2 receptor (IL-2R) nor the expression of the transferrin receptor (TfR) was affected by TGF-beta. After 72 h of culture in the presence of pTGF-beta 1, the expression of the IL-2R and TfR was decreased. The data suggest that in CTLL cells TGF-beta initially slows the progression of cells in all phases of cell cycle. In addition, the initial TGF-beta-mediated decrease of IL-2-induced 3H-thymidine incorporation and cell proliferation in CTLL cells is not due primarily to downregulation of the IL-2R and/or TfR.

Separation of tumor-infiltrating lymphocytes from tumor cells in human solid tumors. A comparison between velocity sedimentation and discontinuous density gradients

The separation of viable tumor-infiltrating lymphocytes (TIL) from surgical biopsies of human solid tumors was achieved by velocity sedimentation at unit gravity or by discontinuous density gradients. The two methods were adapted to small volumes and cell numbers not exceeding 1 X 10(8). The recovery, purity and composition of the TIL-enriched fractions were comparable in the two methods. Density gradients were more rapid, simpler and more practical for preparation under sterile conditions of TIL from clinical material than velocity sedimentation. Lymphocytes in the TIL-enriched fractions obtained by either of the methods were poorly responsive to mitogens. This poor responsiveness is a characteristic of the human TIL and seems to be related to effects exerted by tumor cells.

Polymorphonuclear neutrophil function in malignant lymphomas and effects of splenectomy

Granulocyte (PMN) directional locomotion (migration) in vitro and in vivo, resting nitroblue tetrazolium (NBT)-reduction and adherence to nylon wool of polymorphonuclear neutrophils (PMN) were assayed in 7 patients with Hodgkin's disease (HD) and in 11 patients with non-Hodgkin's lymphoma (NHL) prior to therapy. In most patients with HD, NBT-reduction was increased and in all directional locomotion was markedly decreased both in vitro and in vivo. In addition to being depressed, accumulation of PMN into skin chambers in patients with HD correlated with the peripheral blood count (r = 0.95). In vitro directional migration of PMN in NHL was depressed in half the patients, but increased in the in vivo assay. After splenectomy, PMN-adherence tended to increase and NBT-reduction to decrease. These findings are compatible with a constant cellular defect of PMN in HD, whereas in NHL abnormal PMN function is more likely mediated by extracellular factors. Abnormal PMN function may correlate with clinical susceptibility to infection in malignant lymphomas.

Growth of human marrow in plasma clot diffusion chambers

Unseparated as well as nonadherent human bone marrow cells produced colonies while suspended within plasma clots contained within diffusion chambers implanted into irradiated mice. The majority of colonies consisted of granulocytes or macrophages. Colony size was significantly increased by the administration of endotoxin prior to implantation of the chambers.