The anticancer drug edelfosine is a potent inhibitor of neovascularization in vivo.

Edelfosine is an alkyl-lysophospholipid that acts as an anticancer agent in vivo. To test the hypothesis that part of its antineoplastic activity may be due to its ability to inhibit the neovascularization on which the progressive growth of all tumors depends, we evaluated edelfosine in vitro and in vivo for antiangiogenic activity. Edelfosine acted directly on cultured capillary endothelial cells, inhibiting their migration toward the angiogenic factor, basic fibroblastic growth factor (bFGF), at doses of 8-200 nM. When given systemically to rats (20 mg/kg i.p. twice daily), edelfosine was well tolerated and antiangiogenic. The majority of treated animals became unable to mount a corneal neovascular response to a pellet releasing bFGF, whereas vigorous vessel ingrowth was seen in untreated controls.

The effect of edelfosine on CTP:cholinephosphate cytidylyltransferase activity in leukemic cell lines.

Analogs of ether phospholipids have been shown to have selective anti-neoplastic activity. The compounds are known to inhibit phospholipid biosynthesis. This paper examines the effect of the alkyl-lysophospholipid, edelfosine, on the rate-limiting enzyme, CTP:cholinephosphate cytidylyltransferase, in de novo phosphatidylcholine synthesis in sensitive and resistant leukemic cell lines. Enzyme activity was measured by the incorporation of 14C-phosphocholine into CDP-choline by lysates of HL60 and K562; cells demonstrated inhibition of incorporation of 14C-phosphocholine in HL60 cell lysates but no inhibition in K562 lysates. Partial purification of cytidylyltransferase by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting demonstrated similarity between the enzyme isolated from each cell line. Cloning and sequencing of cytidylyltransferase cDNA of HL60 cells was accomplished using a probe encoding the entire protein sequence of the K562 cytidylyltransferase gene. A substitution at nucleotide 751 from A in the HL60 cell cDNA clone to G in the K562 cDNA clone resulted in a change in amino acid number 251 from lysine (positively charged) in the HL60 enzyme to glutamic acid (negatively charged) in the K562 enzyme. This negative charge in the lipid-binding domain of the K562 enzyme may result in a weaker binding of edelfosine and the observed decrease in activity, as evidenced by resistance to edelfosine by K562 cells.

Improving the efficacy of preoperative autologous blood donation in patients with low hematocrit: a randomized, double-blind, controlled trial of recombinant human erythropoietin.

The effects of therapy with recombinant human erythropoietin (Epoetin alfa) on erythropoiesis, preoperative autologous blood donation, and risk of exposure to allogeneic blood were evaluated in 204 patients scheduled to undergo elective orthopedic surgery. Study protocol required patients to have a baseline hematocrit < or = 39% and surgery scheduled 25-35 days in advance. Patients were randomized to two equal groups and were seen at study centers every 3-4 days within the 21-day trial period. At each visit, phlebotomy(< or = 450 mL) was performed if the hematocrit was > or = 33%, and Epoetin alfa (600 U/kg) or placebo was administered intravenously. A total of 173 patients were assessable; 31% of placebo recipients and 20% of Epoetin alfa recipients required allogeneic transfusion (p = 0.09). Logistic regression modeling showed that the risk of allogeneic transfusion was reduced by Epoetin alfa (p = 0.025). When patients receiving > 6 units of blood (necessitating allogeneic units) were excluded from analysis, 29% of placebo recipients and 14% of Epoetin alfa recipients were exposed to allogeneic blood (p = 0.015). Epoetin alfa recipients predonated more autologous units than did placebo recipients (4.5 vs 3.0 units, respectively; p < 0.001), and their production of red blood cells increased significantly more over baseline production values (668 vs 353 mL, respectively; p < 0.05). These results demonstrate that administration of Epoetin alfa stimulates erythropoiesis, allows predonation of more units of autologous blood, and reduces the risk of exposure to allogeneic blood. Optimal dosing regimens and surgical patients most likely to benefit fro Epoetin alfa therapy must be established.

Response of human multiple myeloma-derived cell lines to alkyl-lysophospholipid.

Clinical studies using high-dose chemotherapy and autologous bone marrow transplantation in multiple myeloma report improvement in tumor regression. The potential success of this approach may be compromised because of the myeloma cell burden. A promising approach is chemopurging of bone marrow with alkyl-lysophospholipids (ALP), a new class of antitumor agents. Using a limiting dilution assay, we tested ALP against several drug-resistant human myeloma cell lines: RPMI 8226/S, 8226/DOX40, 8226/LR-5, 8226/MR-20, 8226/DOX1V, and 8226/MDR10V. IC50 values were approximately 6 microg/mL, for all cell lines evaluated. ALP was effective against all cells, with mean log kills ranging from 2.48 to 4.95. Cytotoxicity was temperature-dependent. Survival curves of cell lines exposed to ALP showed a steep slope during the first 4 hours of exposure, with little additional cell kill after 24 hours. Dose-response curves after drug exposure for 4 and 24 hours reached plateaus at 75 and 25 microg/mL, respectively. Increasing concentrations of ALP caused a sustained increase in resting [Ca2+]i of sufficient magnitude to induce cell death. These results suggest that ALP is an effective cytotoxic agent even in cells known to be resistant to alkylating agents and other classes of cytotoxic drugs.

The effect of recombinant human erythropoietin on the efficacy of autologous blood donation in patients with low hematocrits: a multicenter, randomized, double-blind, controlled trial.

BACKGROUND: This randomized controlled study was undertaken to determine the effect of recombinant human erythropoietin (rHuEPO) on erythropoiesis, autologous blood collection, and allogeneic transfusion risk in elective surgery patients with low baseline hematocrits. STUDY DESIGN AND METHODS: Patients (n = 204) with low baseline hematocrits ( < or = 39%), scheduled for orthopedic surgery within 25 to 35 days, were seen every 3 to 4 days for 21 days. At each visit, 450 mL of blood was collected if the hematocrit was > or = 33 percent, and rHuEPO (600 U/kg) or placebo was administered intravenously. RESULTS: One hundred seventy-three patients were evaluable. The number of autologous units collected from the rHuEPO and control groups, respectively, was 4.5 +/- 1.0 and 3.0 +/- 1.1 (p < 0.001), and marrow production of red cells increased by 668 +/- 222 and 353 +/- 155 mL over and above baseline production (p < 0.05). Allogeneic blood transfusion was required by 31 percent of control and 20 percent of rHuEPO patients (p = 0.09). Excluding 8 patients who received > 6 units, 29 percent of control and 14 percent of rHuEPO patients required allogeneic blood (p = 0.015). Logistic regression modeling determined that the risk of allogeneic transfusion was reduced by rHuEPO (p = 0.025). CONCLUSION: The use of rHuEPO stimulates erythropoiesis, permits the storage of more autologous blood, and reduces allogeneic transfusion risk in patients with low hematocrits who are undergoing elective orthopedic surgery. Additional studies are necessary to determine the optimal schedules of rHuEPO administration and autologous blood collection as well as the cost-effectiveness of this strategy.

High dose cyclophosphamide, fractionated total body irradiation with involved field irradiation and autologous bone marrow transplantation in malignant lymphoma.

The objective of this clinical trial was to determine if radiation to areas of recurrence or bulky disease prior to total body irradiation (TBI) and chemotherapy followed by autologous bone marrow transplantation (ABMT) altered the site of relapse and/or prolonged survival. Forty-eight patients with recurrent or refractory malignant lymphoma were treated with high-dose cyclophosphamide and fractionated TBI followed by ABMT. Thirty-four patients were eligible to receive involved field radiation therapy (IF-RT) to sites of recurrence or bulky disease. The overall response rate in 46 evaluable patients was 89% with 33 complete remissions (CR) and 8 partial remissions (PR). In a multivariant analysis increasing LDH, decreased serum albumin, older age, and lack of sensitivity to prior chemotherapy were associated with poorer survival. There were 10 deaths due to treatment related complications, 8 died of pulmonary complications of whom 6 were in CR. Of 11 who had received IF-RT and subsequently relapsed, 4 recurred in or adjacent to the involved field. We conclude that intensive chemo-radiotherapy proved to be an effective salvage therapy for patients with recurrent malignant lymphoma, resulting in a projected actuarial 33% DFS at 5 years, but was associated with a high transplant-related mortality.

A phase II trial of autologous bone marrow transplantation (ABMT) in acute leukemia with edelfosine purged bone marrow.

Alkyl-lysophospholipid compounds which are selectively cytotoxic to neoplastic cells and relatively sparing of normal marrow progenitor cells are appealing as purging agents to rid remission marrows of residual leukemic cells. A multi-institutional phase II study was conducted in 57 patients with acute leukemia (50 AML and 7 ALL) in which remission marrows were purged in vitro and reinfused after ablative chemotherapy. The median time for granulocyte recovery to 500/microliter was 33 days and for platelet recovery to 25000/microliter was 46 days. The overall DFS and survival was 37% and 46% respectively. Transplantation in first remission gave a better survival than transplant in a subsequent remission.

Establishment and characterization of a new Ph1-positive chronic myeloid leukemia cell line MC3 with trilineage phenotype and an altered p53 gene.

A new Ph1-positive leukemic cell line (MC3) expressing the P210bcr/abl oncoprotein was established from a patient with CML in blast crisis. The MC3 cells showed the trilineage phenotype of myeloid, lymphoid (CD19) and megakaryocytoid lineages, and had a proliferative response to rhIL-1 and rhIL-3 in the serum-free culture. These results and the expression of CD34 indicated that the MC3 cells have characteristics of hematopoietic progenitor cells. Recently, it has been documented that alterations of the p53 gene in leukemic cells are frequently detected during the blast crisis of CML. The MC3 cells contained the altered p53 gene. In addition, the original leukemic cells showed the point-mutational activation of the N-ras gene and an additional chromosomal abnormality inv(3q), but the MC3 cells contained no such abnormalities, indicating that not all of the original leukemic cells had these abnormalities. Thus, the MC3 cell line may provide several insights into investigations of the blast crisis in CML as well as hematopoietic progenitor cells.

Selective inhibition of adhesion molecule expression by edelfosine (ET-18-OCH3) on human umbilical vein or microvascular endothelium.

An abundance of data is accumulating that suggest that if one can block endothelial cell-leukocyte binding or inhibit cell adhesion molecules (CAM), inflammatory events can be greatly diminished. In this report, we demonstrate that an alkyl-lysophospho-lipid compound (ET-18-OCH3) can decrease adhesion molecule expression on cultured human micro- and macrovascular endothelial cell lines. ET-18 selectively decreased CAM expression; CD31 was decreased, however. Vascular CAM-1 tumor necrosis factor-alpha-induced expression was not altered. Intercellular adhesion molecule 1 expression was decreased, but endoglin expression was not affected. Thus, we have demonstrated nontoxic downmodulation of vascular CAM expression in vitro. Whether this compound will have anti-inflammatory properties needs to be clarified in animal models.

A phase III trial of high-dose cytosine arabinoside with or without etoposide in relapsed and refractory acute myelogenous leukemia. A Southeastern Cancer Study Group trial.

A phase III clinical trial was developed to test whether the addition of etoposide to a high-dose cytosine arabinoside regimen would improve the remission rate, duration of remission, and survival in relapsed and refractory patients with acute myelogenous leukemia. One hundred and thirty-one patients stratified by age, performance status, percentage of marrow blasts, platelet count, bilirubin and presence or absence of clinical infection, refractory or relapsed (+/- 9 months) were randomized to receive high-dose cytosine arabinoside, 3 g/m2 every 12 h for 6 days with or without three doses of etoposide, 100 mg/m2 days 7-9. Of 67 patients randomized to cytosine arabinoside alone, 31% obtained a complete remission with a median remission duration of 11.9 months. Of 66 patients randomized to the combination regimen, 38% obtained a complete remission with a median duration of 25 months. None of these differences were statistically significant. Significantly (p = 0.036) longer survival was seen in patients on the combination regimen under the age of 50. There was no difference in overall survival. Six and 8%, respectively, of patients were free of disease at 5 years. The addition of etoposide to a high-dose cytosine arabinoside regimen had at best a marginal effect at the expense of some increase in toxicity.

Late intensification therapy in adult acute lymphoid leukemia: long-term follow-up of the Southeastern Cancer Study Group experience.

One hundred and ninety-two evaluable patients were treated on a multicenter protocol for adult acute lymphoid leukemia to determine in a prospective randomized fashion if late intensification chemotherapy beginning after about six months of treatment would improve remission duration and survival. The complete remission rate was 60%. The median remission duration from beginning of maintenance was 18.7 versus 25.9 months (P = 0.36) for standard maintenance therapy and late intensification, respectively, and the median survival from randomization was 25.8 versus 28.5 months (P = 0.94) respectively. There was a suggestion that the late intensification strategy was helpful with respect to remission duration, and this trend was sustained in long-term follow-up. However, relapse proved to be common during the earlier phases of treatment; thus, insufficient numbers of patients were available at the randomization point to conclusively address the possible value of late intensification. Intensive therapy earlier in the course of treatment should be evaluated, including transplantation in selected patients.

Erythropoietin response to anaemia is not altered by surgery or recombinant human erythropoietin therapy.

Recombinant human erythropoietin (EPO) therapy has been shown to increase red blood cell (RBC) production and facilitate autologous blood donation before elective surgery. However, recent reports have suggested that surgery and/or EPO therapy may suppress endogenous erythropoietin secretion in response to anaemia. We therefore analysed the haemoglobin/erythropoietin relationship preoperatively and postoperatively in 71 autologous blood donors subjected to aggressive phlebotomy and six treatments with either EPO (150 U/kg, n = 16, 300 U/kg, n = 18, or 600 U/kg, n = 19) or placebo (n = 18). Using data from the three preoperative study visits, the linear relationship between log erythropoietin and haemoglobin was determined for each of the 18 placebo patients. We found no significant differences in the slopes of the relationships in this group during aggressive phlebotomy. Furthermore, there was no evidence of a significant difference in the erythropoietin level recorded postoperatively for each patient to that predicted from the patient's postoperative haemoglobin level, based on the haemoglobin/log erythropoietin relationship preoperatively. Similarly, for each of the EPO-treated groups, there was no evidence of a significant difference when comparing the recorded erythropoietin level to that predicted from each patient's postoperative haemoglobin level, based on the haemoglobin/log erythropoietin relationship preoperatively. We conclude that preoperative recombinant human erythropoietin therapy and/or surgery do not adversely affect the postoperative erythropoietin response to anaemia.

Human leukemia K562 cell mutant (K562/OA200) selected for resistance to okadaic acid (protein phosphatase inhibitor) lacks protein kinase C-epsilon, exhibits multidrug resistance phenotype, and expresses drug pump P-glycoprotein.

A human leukemia K562 cell mutant (K562/OA200) selected for resistance to okadaic acid (OA), an inhibitor of protein phosphatases 1 and 2A (PP1/PP2A), has been established. In wild type cells, the cytotoxicity of OA was associated with mitotic arrest and concentration- and time-dependent DNA fragmentation, a hallmark of apoptosis. The mutant was 100-fold more resistant to OA in terms of effects on these parameters. Although the synthesis of several proteins was altered, enzyme assay and immunoblot analysis indicated that the levels of PP1 and PP2A were unchanged in the mutant. Protein kinase C (PKC) assays and immunoblot analysis of calcium-dependent (cPKC) and calcium-independent (nPKC) isoforms revealed that nPKC-epsilon was strikingly absent in the mutant, which otherwise expressed in comparable amounts all other isotypes (cPKC-alpha, cPKC-beta, and nPKC-zeta) also present in the wild type. Northern blot analysis confirmed an absence of PKC-epsilon mRNA in the mutant cells. The OA200 cells were cross-resistant not only to another PP1/PP2A inhibitor, calyculin A, but also to structurally unrelated anticancer drugs (such as vinblastine and taxol) and furthermore, overexpressed the verapamil-sensitive drug pump P-glycoprotein at both the protein and mRNA levels. The mutant, however, was not cross-resistant to several PKC inhibitors tested including cardiotoxin, mastoparan, staurosporine, and an alkylphospholipid. Cardiotoxin, at a subtoxic concentration, enhanced by 6-fold vinblastine cytotoxicity in OA200 cells. These findings indicate that the multidrug resistance phenotype can be induced by cytotoxic agents other than conventional anticancer drugs, show that the development of multidrug resistance is not necessarily associated with increased cPKC activity, and identify certain PKC inhibitors that have potential as resistance modulators.

Bone marrow purging in acute leukemia with alkyl-lysophospholipids: a new family of anticancer drugs.

The alkyl-lysophospholipids are a new family of anticancer drugs which target the cell membrane as their site of action. Enzymes involved in signal transduction (protein kinase C and phosphatidylinositol phospholipase C), phospholipid biosynthesis (lysophosphatidyl acyltransferase and CTP:cholinephosphate cytidylyltransferase) and maintenance of membrane integrity (Na,K ATPase sodium pump) are inhibited. A unique feature of the alkyl-lysophospholipids is their selective cytotoxicity to neoplastic cells. This suggests that the compound would be an excellent agent for purging residual leukemic cells from marrows of patients in remission prior to autologous bone marrow transplantation. Preclinical studies in a murine leukemia model and in an in vitro human system demonstrated successful elimination of leukemic cells from a mixture of normal and leukemic marrows. Twenty-nine poor risk patients with acute leukemia underwent autologous bone marrow transplantation and were reinfused with marrow treated in vitro with edelfosine. Nine of these patients remain in remission free of leukemia from 368 to 1369 days. These encouraging results warrant further investigation.

Effect of herbimycin A, an inhibitor of tyrosine kinase, on protein tyrosine kinase activity and phosphotyrosyl proteins of Ph1-positive leukemia cells.

Herbimycin A, a benzoquinonoid anasamycin antibiotic, preferentially inhibited the in vitro growth of Ph1-positive leukemia cell lines. On the other hand, genistein, which was developed as an inhibitor of receptor-type tyrosine kinase, and other protein kinase inhibitors showed no selective inhibition of Ph1-positive leukemia cell growth. Herbimycin A also displayed an abrogative effect on the transformation of murine hematopoietic cells by transfection with a bcr/abl oncoprotein-expressing retroviral vector. The antitumor action of herbimycin A on Ph1-positive leukemia cells is related to an inhibition of activity of bcr/abl protein tyrosine kinase and a subsequent reduction of the constitutive phosphotyrosyl proteins, however, the antibiotic has no effect on the expression of bcr/abl mRNA and oncoprotein. Therefore, herbimycin A may provide an important insight into the oncogenic action of bcr/abl oncoprotein and the future development of oncoprotein-targeted therapeutic agents.

Inhibition of induced angiogenesis in a human microvascular endothelial cell line by ET-18-OCH3.

Alkyl-lysophospholipids are a group of anti-cancer compounds that have previously been shown to have the unique feature of being selectively toxic to neoplastic tissues. One of these compounds, ET-18-OCH3, has been used for purging bone marrow of cancer cells in phase I clinical trials. Tumor-induced angiogenesis has been directly correlated with tumor growth and metastasis. In this study, we examined the effect ET-18-OCH3 has on a human microvascular endothelial cell line (HMEC-1), including the following functions: angiogenesis, cell-adhesion molecule expression, and cell-junction integrity. We found that ET-18-OCH3 (in vitro) reversibly inhibited induced angiogenesis at levels that did not affect viability. At lower concentrations, ET-18-OCH3 down-regulated the expression of cell-adhesion molecules and affected the integrity of cell-to-cell junctions. This observation demonstrates this versatile family of compounds to have additional targets of action.

Different mechanisms of inhibition by alkyl-lysophospholipid and phorbol ester of granulocyte-macrophage colony-stimulating factor binding to human leukemic cell lines.

We investigated the effects of rac-1-O-octadecyl-2-O-methyl-glycero-3-phosphocholine (ET-18-OCH3) and 12-O-tetradecanoylphorbol-13-acetate (TPA) on granulocyte-macrophage colony-stimulating factor (GM-CSF) binding to human leukemic cell lines HL60, U937, KG-1, KG-1a, and K562. HL60, U937, and KG-1 exhibited the high-affinity receptors, but KG-1a and K562 revealed no demonstrable receptors. ET-18-OCH3 inhibited GM-CSF binding to HL60, U937, and KG-1 cells with a half-maximal inhibitory concentration of 16, 10, and 78 microM, respectively. ET-18-OCH3 at 10 microM reduced GM-CSF binding sites on HL60, U937, and KG-1, but had little effect on the dissociation constant (Kd). ET-18-OCH3 at 10 and 30 microM significantly (p < 0.01) decreased, in a dose-dependent manner, the total uptake, surface binding, and internalization of GM-CSF. The internalization of GM-CSF was more profoundly inhibited than its surface binding. TPA at 1 and 10 nM inhibited GM-CSF binding. Inhibition of GM-CSF binding by a combination of ET-18-OCH3 (10 microM) and TPA (1 or 10 nM) was less than additive, and ET-18-OCH3 partially inhibited TPA-induced protein kinase C (PKC) depletion in the cytosol and translocation to the particulate fractions. It is suggested that the inhibition of GM-CSF binding by ET-18-OCH3 is due in part to disruption of the plasma membrane and that the inhibition of GM-CSF binding by TPA is due to activation of PKC.

A phase III trial of recombinant human erythropoietin therapy in nonanemic orthopedic patients subjected to aggressive removal of blood for autologous use: dose, response, toxicity, and efficacy.

BACKGROUND: Previous clinical trials have shown that the use of recombinant human erythropoietin (EPO) can facilitate autologous blood donation and reduce allogeneic blood transfusions in autologous blood donors who are anemic at first donation. However, the role of EPO therapy in nonanemic patients remains undefined. To identify this role, a randomized, controlled, multicenter dose-escalation trial was conducted in patients whose initial hematocrit was > 39 percent (0.39). STUDY DESIGN AND METHODS: EPO (150, 300, or 600 units/kg) or placebo was administered intravenously at each of six phlebotomy visits over a 3-week study period. Sixteen (14%) of 116 patients were unable to complete the treatment protocol because of adverse events (n = 11) or for personal reasons (n = 5); 2 patients (1 EPO and 1 placebo) experienced serious adverse events. RESULTS: In 91 evaluable patients, additional red cell production during the study period was 440 +/- 176, 621 +/- 215, 644 +/- 196, and 856 +/- 206 mL (mean +/- SD), respectively, for patients receiving placebo and EPO at 150, 300, and 600 units/kg (p < 0.05 for all EPO groups compared to placebo). However, the percentages of patients in each group who received allogeneic blood did not differ: 2 (9%) of 23 placebo patients and 6 (9%) of 68 EPO patients. CONCLUSION: It is concluded that, while EPO therapy increased preoperative red cell production, no clinical benefit could be demonstrated in autologous blood donors who were not anemic at first blood donation.

High-dose carboplatin in the treatment of hematologic malignancies.

Carboplatin is a second-generation platinum complex developed to be less ototoxic and nephrotoxic than cisplatin. The major toxicity was found to be myelosuppression; thus, it was tried in acute leukemia. When given by daily bolus injection for 5 days, carboplatin exhibited some activity but was associated with additional nonhematologic toxicity as well. When administered by continuous infusion, responses were higher and toxicity less. The Eastern Cooperative Oncology Group (ECOG) conducted a phase II study of carboplatin 315 mg/m2 daily given by continuous infusion for 5 days to adults with refractory and relapsed acute leukemia. A second course was given if the bone marrow on day 14 revealed persistent leukemia. Those achieving a complete remission (CR) were given an additional course as consolidation. The median age was 49 years among acute myelogenous leukemia (AML) patients and 46 years in acute lymphoblastic leukemia (ALL) patients. Of 46 eligible patients enrolled in the study (36 AML and 10 ALL), 8 (17%) achieved a CR (6 AML and 2 ALL). Remissions were observed in 2 of 10 primary refractory patients (1 AML and 1 ALL). When treated in first relapse, 5 of 14 patients (36%) achieved a CR. In 38 instances marrow specimens were examined after treatment; 10 (26%) showed no change, 16 (42%) were hypoplastic, and 12 (32%) were hypoplastic with residual leukemic cells. Of the 18 deaths that occurred on study, 14 were due to infection, 2 due to infection and bleeding, 1 due to uncontrolled gastrointestinal bleeding and 1 due to graft-versus-host disease in a patient who had relapsed after bone marrow transplantation. Marrow suppression was usually prolonged. Nonhematologic toxicity was mild. Gastrointestinal toxicity consisted of easily controlled nausea and vomiting. Three patients had grade 3 diarrhea. Grade 3 or more renal toxicity was observed in 8 patients, all of whom had received nephrotoxic antibiotics for treatment of bacterial or fungal infections. One patient died of renal failure that developed near the end of a second induction course. Ototoxicity was observed in 11 patients (24%) and was grade 2 or less in all but 3. These results indicate that carboplatin is an active agent in leukemia. Further studies are under way in combination with other agents such as etoposide, mitoxantrone, 5-azacytidine, and daunorubicin in treatment of acute leukemia and in combination with ifosfamide and etoposide in refractory lymphomas.

Structure-function relationships of alkyl-lysophospholipid analogs in selective antitumor activity.

This investigation was initiated in order to delineate the structure-function relationship of the anticancer alkyl-lysophospholipids and assess their degree of selective cytotoxicity toward neoplastic cells. A series of glycerol phosphocholine analogs with varying substitutions in the sn-1 and sn-2 position were tested for their inhibitory activity as measured by thymidine incorporation, clonogenic assays and effects on protein kinase C activity against a series of human leukemic cell lines and healthy bone marrow progenitor cells. The IC50 was determined for each of the compounds in each cell line and healthy bone marrow cells following a 4-h incubation. The data indicated that a 16-18 carbon chain at the sn-1 coupled with a short substitution at sn-2 had the broadest antitumor activity and was the least toxic to normal bone marrow cells. The results provide a number of useful leads toward the design and development of potentially more active phospholipid compounds.