Phase II study of miltefosine (hexadecylphosphocholine) in advanced soft tissue sarcomas of the adult--an EORTC Soft Tissue and Bone Sarcoma Group Study

Evaluation of release and pharmacokinetics of hexadecylphosphocholine (miltefosine) in phosphatidyldiglycerol-based thermosensitive liposomes

Hexadecylphosphocholine (HePC, Miltefosine) is a drug from the class of alkylphosphocholines with an antineoplastic and antiprotozoal activity. We previously reported that HePC uptake from thermosensitive liposomes (TSL) containing 1,2-dipalmitoyl-sn-glycero-3-phosphodiglycerol (DPPG₂) into cancer cells is accelerated at mild hyperthermia (HT) resulting in increased cytotoxicity. In this study, we compared HePC release of different TSL formulations in serum. HePC showed rapid but incomplete release below the transition temperature (T_m) of investigated TSL formulations in serum. Short heating (5 min) to 42 °C increased HePC release from DPPG₂-TSL (T_m = 41 °C) by a factor of two in comparison to body temperature (37 °C). Bovine serum albumin (BSA) induced HePC release from DPPG₂-TSL comparable to serum. Furthermore, multilamellar vesicles (MLV) were capable to extract HePC from DPPG₂-TSL in a concentration- and temperature-dependent manner. Repetitive exposure of DPPG₂-TSL to MLV at 37 °C led to a fast initial release of HePC which slowed down after subsequent extraction cycles finally reaching approx. 50% HePC release. A pharmacokinetic study in rats revealed a biphasic pattern with an immediate clearance of approx. 50% HePC whereas the remaining 50% HePC showed a prolonged circulation time. We speculate that HePC located in the external leaflet of DPPG₂-TSL is rapidly released upon contact with suitable biological acceptors. As demonstrated by MLV transfer experiments, asymmetric incorporation of HePC into the internal leaflet of DPPG₂-TSL might improve HePC retention in presence of complex biological media and still give rise to HT-induced HePC release.

Resolution of Acanthamoeba Keratitis with Adjunctive Use of Oral Miltefosine

Purpose: To report a series of cases demonstrating the resolution of Acanthamoeba keratitis (AK) with adjunctive use of oral miltefosine.Methods: Retrospective case series.Results: The first case was a 27-year-old female who presented with severe pain and photophobia. The diagnosis of AK was made with confocal microscopy, which revealed a significant burden of stromal cysts. After approximately 2 weeks of adjunctive oral miltefosine therapy, there was a severe inflammatory response within the cornea followed by quick resolution of the AK. The second case was a 31-year-old male in whom the diagnosis of AK was confirmed by culture and polymerase chain reaction. Adjunctive oral miltefosine was started 3 months after presentation, leading to a quick resolution.Conclusions: Oral miltefosine may have cysticidal properties and should be considered as adjunctive therapy for the treatment of AK, particularly in cases with a significant burden of cysts or in cases recalcitrant to other treatments.

Alkylphospholipids are Signal Transduction Modulators with Potential for Anticancer Therapy

BACKGROUND

Alkylphospholipids (APLs) are synthetically derived from cell membrane components, which they target and thus modify cellular signalling and cause diverse effects. This study reviews the mechanism of action of anticancer, antiprotozoal, antibacterial and antiviral activities of ALPs, as well as their clinical use.

METHODS

A literature search was used as the basis of this review.

RESULTS

ALPs target lipid rafts and alter phospholipase D and C signalling cascades, which in turn will modulate the PI3K/Akt/mTOR and RAS/RAF/MEK/ERK pathways. By feedback coupling, the SAPK/JNK signalling chain is also affected. These changes lead to a G2/M phase cell cycle arrest and subsequently induce programmed cell death. The available knowledge on inhibition of AKT phosphorylation, mTOR phosphorylation and Raf down-regulation renders ALPs as attractive candidates for modern medical treatment, which is based on individualized diagnosis and therapy. Corresponding to their unusual profile of activities, their side effects result from cholinomimetic activity mainly and focus on the gastrointestinal tract. These aspects together with their bone marrow sparing features render APCs well suited for modern combination therapy. Although the clinical success has been limited in cancer diseases so far, the use of miltefosine against leishmaniosis is leading the way to better understanding their optimized use.

CONCLUSION

Recent synthetic programs generate congeners with the increased therapeutic ratio, liposomal formulations, as well as diapeutic (or theranostic) derivatives with optimized properties. It is anticipated that these innovative modifications will pave the way for the further successful development of ALPs.

The safety and efficacy of miltefosine in the long-term treatment of post-kala-azar dermal leishmaniasis in South Asia - A review and meta-analysis

BACKGROUND

Miltefosine (MF) is the only oral drug available for treatment of visceral leishmaniasis (VL) and post-kala-azar dermal leishmaniasis (PKDL). Although the drug is effective and well tolerated in treatment of VL, the efficacy and safety of MF for longer treatment durations (>28 days) in PKDL remains unclear. This study provides an overview of the current knowledge about safety and efficacy of long treatment courses with MF in PKDL, as a strategy in the VL elimination in South Asia.

METHODOLOGY/PRINCIPAL FINDINGS

Literature was searched systematically for articles investigating MF treatment in PKDL. A meta-analysis included eight studies (total 324 PKDL patients) to estimate the efficacy of MF in longer treatment regimens (range 6-16 weeks). We found a per-protocol (PP) initial cure rate of 95.2% (95%CI 89.6-100.8) and a PP definite cure rate of 90% (95%CI 81.6-96.3). Descriptive analysis showed that 20% of patients experienced adverse events, which mostly had an onset in the first week of treatment and were likely to get more severe after four weeks of treatment. Gastrointestinal (GI) side effects such as vomiting, nausea, diarrhoea, and abdominal pain were most common.

CONCLUSIONS/SIGNIFICANCE

Longer treatment regimens with MF are effective in PKDL patients in India, however with the caveat that the efficacy has recently been observed to decline. GI side effects are frequent, although mostly mild or moderate. However, on the basis of limited data, we cannot conclude that longer MF treatment regimens are safe. Moreover, VL and PKDL pharmacovigilance studies indicate a risk for serious adverse events, questioning the safety of MF. The provision of safer treatment regimens for PKDL patients are therefore recommended. Until these regimens are identified, it should be considered to halt the use of MF monotherapy for PKDL in order to preserve the drug's efficacy.

Inhibition of Akt and other AGC kinases: A target for clinical cancer therapy?

AGC kinases have been identified to contribute to cancer development and progression. Currently, most AGC inhibitors in clinical development are Akt inhibitors such as MK-2206 or GDC-0068, which are known to promote cell growth arrest and to sensitize cancer cells to radiotherapy. Response rates in clinical trials with single agent Akt inhibitors are typically low. The observed adverse events are within the expected limits for compounds inhibiting the PI3K-mTOR axis. Preclinical and early clinical data for combination therapies are accumulating. Based on these data, several Akt inhibitors are about to enter phase 3 trials. Besides drugs that target Akt, p70S6K inhibitors have entered clinical development. Again, the response rates were rather low. In addition, relevant toxicities were identified, including a risk for coagulopathies with these compounds. Multi-AGC kinase inhibitors are also in early clinical development but the data is not sufficient yet to draw conclusions regarding their efficacy and side-effect profile. PKC inhibitors have been tested in the phase 3 setting but were found to lack efficacy. More trials with isoform-specific PKC inhibitors are expected. Taken together, therapies with AGC kinase inhibitors as single agents are unlikely to meet success. However, combination therapies and a precise stratification of patients according to the activation of signaling axes may increase the probability to see relevant efficacy with these compounds. The emergence of onco-immunotherapies holds some new challenges for these agents.

Alkylphospholipids: An update on molecular mechanisms and clinical relevance

Alkylphospholipids (APLs) represent a new class of drugs which do not interact directly with DNA but act on the cell membrane where they accumulate and interfere with lipid metabolism and signalling pathways. This review summarizes the mode of action at the molecular level of these compounds. In this sense, a diversity of mechanisms has been suggested to explain the actions of clinically-relevant APLs, in particular, in cancer treatment. One consistently reported finding is that APLs reduce the biosynthesis of phosphatidylcholine (PC) by inhibiting the rate-limiting enzyme CTP:phosphocholine cytidylyltransferase (CT). APLs also alter intracellular cholesterol traffic and metabolism in human tumour-cell lines, leading to an accumulation of cholesterol inside the cell. An increase in cholesterol biosynthesis associated with a decrease in the synthesis of choline-containing phospholipids and cholesterol esterification leads to a change in the free-cholesterol:PC ratio in cells exposed to APLs. Akt phosphorylation status after APL exposure shows that this critical regulator for cell survival is modulated by changes in cholesterol levels induced in the plasma membrane by these lipid analogues. Furthermore, APLs produce cell ultrastructural alterations with an abundant autophagic vesicles and autolysosomes in treated cells, indicating an interference of autophagy process after APL exposure. Thus, antitumoural APLs interfere with the proliferation of tumour cells via a complex mechanism involving phospholipid and cholesterol metabolism, interfere with lipid-dependent survival-signalling pathways and autophagy. Although APLs also exert antiparasitic, antibacterial, and antifungal effects, in this review we provide a summary of the antileishmanial activity of these lipid analogues. This article is part of a Special Issue entitled: Membrane Lipid Therapy: Drugs Targeting Biomembranes edited by Pablo V. Escribá.

Akt inhibitors in cancer treatment: The long journey from drug discovery to clinical use (Review)

Targeted cancer therapies are used to inhibit the growth, progression, and metastasis of the tumor by interfering with specific molecular targets and are currently the focus of anticancer drug development. Protein kinase B, also known as Akt, plays a central role in many types of cancer and has been validated as a therapeutic target nearly two decades ago. This review summarizes the intracellular functions of Akt as a pivotal point of converging signaling pathways involved in cell growth, proliferation, apoptotis and neo‑angiogenesis, and focuses on the drug design strategies to develop potent anticancer agents targeting Akt. The discovery process of Akt inhibitors has evolved from adenosine triphosphate (ATP)‑competitive agents to alternative approaches employing allosteric sites in order to overcome the high degree of structural similarity between Akt isoforms in the catalytic domain, and considerable structural analogy to the AGC kinase family. This process has led to the discovery of inhibitors with greater specificity, reduced side-effects and lower toxicity. A second generation of Akt has inhibitors emerged by incorporating a chemically reactive Michael acceptor template to target the nucleophile cysteines in the catalytic activation loop. The review outlines the development of several promising drug candidates emphasizing the importance of each chemical scaffold. We explore the pipeline of Akt inhibitors and their preclinical and clinical examination status, presenting the potential clinical application of these agents as a monotherapy or in combination with ionizing radiation, other targeted therapies, or chemotherapy.

Anti-tumor activities of lipids and lipid analogues and their development as potential anticancer drugs

Lipids have the potential for development as anticancer agents. Endogenous membrane lipids, such as ceramides and certain saturated fatty acids, have been found to modulate the viability of tumor cells. In addition, many tumors over-express cyclooxygenase, lipoxygenase or cytochrome P450 enzymes that mediate the biotransformation of ω-6 polyunsaturated fatty acids (PUFAs) to potent eicosanoid regulators of tumor cell proliferation and cell death. In contrast, several analogous products from the biotransformation of ω-3 PUFAs impair particular tumorigenic pathways. For example, the ω-3 17,18-epoxide of eicosapentaenoic acid activates anti-proliferative and proapoptotic signaling cascades in tumor cells and the lipoxygenase-derived resolvins are effective inhibitors of inflammatory pathways that may drive tumor expansion. However, the development of potential anti-cancer drugs based on these molecules is complex, with in vivo stability a major issue. Nevertheless, recent successes with the antitumor alkyl phospholipids, which are synthetic analogues of naturally-occurring membrane phospholipid esters, have provided the impetus for development of further molecules. The alkyl phospholipids have been tested against a range of cancers and show considerable activity against skin cancers and certain leukemias. Very recently, it has been shown that combination strategies, in which alkyl phospholipids are used in conjunction with established anticancer agents, are promising new therapeutic approaches. In future, the evaluation of new lipid-based molecules in single-agent and combination treatments may also be assessed. This could provide a range of important treatment options in the management of advanced and metastatic cancer.

A phase I and pharmacokinetic study of oral perifosine with different loading schedules in patients with refractory neoplasms

PURPOSE

To determine the maximum tolerated dose (MTD) of perifosine (NSC 639966), an alkylphospholipid modulator of signal transduction, using different oral loading and maintenance regimens in an effort to avoid gastrointestinal toxicity while seeking maximal sustained plasma concentrations.

METHODS

Thirty-one patients with advanced neoplasms were treated with monthly cycles of perifosine loading doses of 300, 600, 900, 1,200 and 1,500 mg (dose levels 1 through 5, respectively) on days 1-2 depending on the actual dose of the initial cycle. For subsequent cycles, perifosine loading doses were reduced to 100, 200, 300, 400 and 1,000 mg at the respective corresponding dose levels. Daily perifosine "maintenance" doses of 50, 100, 150, 200 and 250 mg for levels 1 through 5, respectively, commenced on days 2 or 3 and continued for a total of 21 days. No treatment was given for days 22-27. The pharmacokinetics of perifosine with these schedules was characterized.

RESULTS

Dose-limiting diarrhea developed at or above dose level 4. The MTD and recommended phase II dose was dose level 3B, with a loading dose of 900 mg on day 1 divided into two doses of 450 mg administered 6 h apart and a maintenance dose of 150 mg on day 2 through 21. On subsequent cycles, the loading dose was reduced to 300 mg. Non-gastrointestinal toxicities included three episodes of gout or gout-like syndromes observed at doses above the MTD. The median peak plasma concentration of perifosine achieved at the MTD was approximately 8.3 µg/mL. Four patients had stable disease ranging from 167 to 735 days.

CONCLUSIONS

Perifosine given according to a loading and maintenance schedule can safely sustain concentrations of drug, approaching concentrations achieved in preclinical models with evidence of anti-tumor effect.

Repurposing miltefosine for the treatment of immune-mediated disease?

Miltefosine is an ether lipid that was initially developed for cancer treatment in the early 1980s. Miltefosine largely failed development for oncology, although it was approved for the topical treatment of breast cancer metastasis. It was subsequently discovered that miltefosine is a highly effective treatment of visceral Leishmaniasis, a parasitic disease that affects millions worldwide and causes an estimated 30,000 fatalities each year. Oral treatment with miltefosine is generally well tolerated and has relatively few adverse effects. The exact mechanism of action of miltefosine treatment is still under investigation. Its close resemblance to phospholipids allows it to be quickly taken up by cell membranes and affect related processes, such as lipid metabolism and signaling through lipid rafts. These processes play an important role in the immune response and it comes as no surprise that miltefosine has been successfully tested for the treatment of a number of immune-mediated diseases in preclinical models of disease. Drug repurposing of miltefosine for immune-mediated diseases may provide an opportunity to expand the limited number of drugs that are currently available for therapeutic use.

Miltefosine suppresses inflammation in a mouse model of inflammatory bowel disease

BACKGROUND

The repertoire of immunomodulators that can be used for the treatment of inflammatory bowel disease is limited. The use of these drugs is further restricted by the occurrence of side effects in a proportion of patients. Miltefosine (hexadecylphosphocholine) is a lipid drug developed in the 1980s for the treatment of cancer but is nowadays best known for its application in the oral treatment of leishmaniasis. Although the exact mechanism of action of miltefosine has yet to be elucidated, the drug has previously been shown to inhibit phospholipases and protein kinase C, both key components of proproliferative signal transduction in T cells.

METHODS

Stimulated peripheral blood lymphocyte were treated with miltefosine, and proliferation was measured. We use the CD45RB T-cell transfer colitis model to investigate the effect of miltefosine treatment on intestinal inflammation. Effects on the severity of colitis were studied by histochemical and immunohistochemical staining, and cytokine levels were determined using a cytokine bead array.

RESULTS

Miltefosine inhibited T-cell proliferation in vitro. In the transfer model, miltefosine significantly ameliorated the severity of colitis as measured by clinical, (immuno)histochemical, and biochemical parameters.

CONCLUSIONS

Miltefosine inhibits T-cell proliferation and effectively reduces inflammation in the T-cell transfer model. The drug may therefore be a candidate immunomodulator for inflammatory bowel disease.

Anticancer mechanisms and clinical application of alkylphospholipids

Synthetic alkylphospholipids (ALPs), such as edelfosine, miltefosine, perifosine, erucylphosphocholine and erufosine, represent a relatively new class of structurally related antitumor agents that act on cell membranes rather than on DNA. They selectively target proliferating (tumor) cells, inducing growth arrest and apoptosis, and are potent sensitizers of conventional chemo- and radiotherapy. ALPs easily insert in the outer leaflet of the plasma membrane and cross the membrane via an ATP-dependent CDC50a-containing 'flippase' complex (in carcinoma cells), or are internalized by lipid raft-dependent endocytosis (in lymphoma/leukemic cells). ALPs resist catabolic degradation, therefore accumulate in the cell and interfere with lipid-dependent survival signaling pathways, notably PI3K-Akt and Raf-Erk1/2, and de novo phospholipid biosynthesis. At the same time, stress pathways (e.g. stress-activated protein kinase/JNK) are activated to promote apoptosis. In many preclinical and clinical studies, perifosine was the most effective ALP, mainly because it inhibits Akt activity potently and consistently, also in vivo. This property is successfully exploited clinically in highly malignant tumors, such as multiple myeloma and neuroblastoma, in which a tyrosine kinase receptor/Akt pathway is amplified. In such cases, perifosine therapy is most effective in combination with conventional anticancer regimens or with rapamycin-type mTOR inhibitors, and may overcome resistance to these agents. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism.

Erufosine, an alkylphosphocholine, with differential toxicity to human cancer cells and bone marrow cells

PURPOSE

To investigate the activity and myeloprotective properties of erufosine, a novel alkylphosphocholine (APC), on human malignant cells and normal bone marrow cells.

METHODS

Human or mouse bone marrow cells were exposed to erufosine, miltefosine, perifosine, or edelfosine in CFU-GM assays. Human MDA-MB-231 breast carcinoma, Panc-1 pancreatic carcinoma, and RPMI8226 multiple myeloma cells were exposed to erufosine in colony formation assays. Colony formation of Panc-1 tumor cells and mouse bone marrow cells ex vivo were quantified following intravenous administration of erufosine to tumor-bearing mice. Western blotting methods were applied to human U87 glioblastoma cells exposed to erufosine to investigate Akt inhibition.

RESULTS

Erufosine was less toxic to human and mouse bone marrow cells than perifosine, miltefosine, and edelfosine and was equally toxic to human and mouse CFU-GM. The human cancer cells MDA-MB-231 breast, Panc-1 pancreatic, and RPMI8226 MM cells were more sensitive to erufosine in a colony formation assay than were human bone marrow cells generating an approximately tenfold differential in IC(90) values. Erufosine injected intravenously significantly reduced Panc-1 tumor cell colony formation ex vivo but not mouse bone marrow CFU-GM. Erufosine inhibited Akt phosphorylation in human U87 glioblastoma cells.

CONCLUSIONS

Erufosine offers potential as a novel therapeutic for cancer with a reduced toxicity profile to bone marrow cells compared with other agents in this class. Human cancer cells were more sensitive to erufosine than human or mouse bone marrow cells indicating a favorable therapeutic window for erufosine.

Targeting Akt in cancer therapy

In an effort to improve therapeutic options in cancer, many investigational drugs are being developed to inhibit signaling pathways that promote the survival of cancer cells. The prototypic pathway that promotes cellular survival is the phosphoinositide 3'-kinase/Akt/mammalian target of rapamycin pathway, which is constitutively activated in many types of cancers. Mechanisms for activation of the serine/threonine kinase, Akt, include loss of tumor suppressor PTEN (phosphatase and tensin homolog deleted on chromosome 10) function, amplification or mutation of phosphoinositide 3'-kinase, amplification of Akt, activation of growth factor receptors and exposure to carcinogens. Activation of Akt promotes cellular survival as well as resistance to treatment with chemotherapy and/or radiation therapy. Immunohistochemical analyses have shown that Akt is activated in many types of cancers and preneoplastic lesions, and Akt activation is a poor prognostic factor in various cancers. Taken together, these data demonstrate that Akt is a valid target for inhibition. This review will focus on published data using different approaches to inhibit Akt. We will also consider how the complex regulation of the phosphoinositide 3'-kinase/Akt/mammalian target of rapamycin pathway poses practical issues concerning the design of clinical trials, potential toxicities and the likelihood of finding a therapeutic index when targeting such a critical cellular pathway.

Alkyl phospholipid perifosine induces myeloid hyperplasia in a murine myeloma model

OBJECTIVES

Alkyl-lysophospholipids are a novel class of antitumor agents. Perifosine is a novel alkyl-lysophospholipid that can induce apoptosis in multiple myeloma (MM) tumor cells, both in vitro and in vivo. We investigated the effects of perifosine on the peripheral blood, bone marrow, and spleen of mice inoculated with subcutaneous plasmacytomas.

METHODS

Immunocompromised mice were inoculated with myeloma cell lines and treated with oral perifosine in either a daily or weekly schedule, or with vehicle only. When plasmacytomas reached 2 cm, mice were sacrificed. Terminal blood was analyzed with a Coulter counter, and counts were confirmed by light microscopy. Marrow and spleen were also analyzed by light microscopy.

RESULTS

In control mice, mean hemoglobin was 12 g/dL, white blood cell (WBC) count 7 x 10(9)/L, and mean platelet count was 292 x 10(9)/L. In contrast, the respective values for mice treated with perifosine weekly were 11 g/dL, 9 x 10(9)/L, and 944 x 10(9)/L; and for mice treated with perifosine daily were 10 g/dL, 11 x 10(9)/L, and 752 x 10(9)/L. The increase in WBCs was due, predominantly, to a neutrophilia. Compared to control mice, perifosine treatment induced marrow hypercellularity and splenic white pulp expansion.

CONCLUSIONS

These findings have clinical relevance because myeloid suppression is a dose-limiting toxicity of many cytotoxic agents, and myeloid hyperplasia is usually only observed in the setting of growth factor stimulation. Coupled with its remarkable in vitro MM cytotoxicity, these results strongly support the use of perifosine in clinical trials for patients with MM.

Rationale and clinical application of alkylphospholipid analogues in combination with radiotherapy

Concurrent treatment with radiotherapy and chemotherapy has emerged as an effective strategy to improve clinical outcome of cancer. In addition to combining radiation with classical anticancer agents, several new biological response modifiers are under investigation in pre-clinical and clinical studies. Synthetic alkylphospholipids are anticancer agents that in contrast to most anticancer drugs, do not target DNA, but insert in the plasma membrane and subsequently induce a broad range of biological effects, ultimately leading to cell death. Alkylphospholipids kill tumor cells directly by induction of both apoptotic and non-apoptotic cell death, and indirectly by interference with critical signal transduction pathways involved in phospholipid metabolism and survival. Due to their distinct mode of action, these drugs are considered as attractive candidates to combine with radiotherapy. In this review, we will discuss several alkylphospholipids that reached clinical application. These include first-generation alkyl-lysophospholipids edelfosine and ilmofosine, second-generation alkylphosphocholine-prototype miltefosine and more recently developed analogues perifosine and erucylphosphocholine. We focus on mechanisms of action and the rationale to combine these agents with radiotherapy. The preclinical results on molecular targeting underlying this approach will be reviewed, concluded with first clinical data on combined treatment of radiotherapy with perifosine.

Development of miltefosine as an oral treatment for leishmaniasis

Miltefosine was originally formulated and registered as a topical treatment for cutaneous cancers. For this indication and in subsequent development for leishmaniasis, a large body of non-clinical data has been generated. The gastrointestinal organ is the main site of toxicity, in both animal and in human studies. The testis and retina were identified as target organs in rats, although corresponding changes were not observed in clinical studies in humans. In terms of pharmacokinetics, the terminal elimination half-life is long (84h and 159h in rats and dogs respectively). Miltefosine is widely distributed in body organs and not metabolized by cytochrome P450 enzymes in vitro. The drug is embryotoxic and fetotoxic in rats and rabbits, and teratogenic in rats but not in rabbits. It is therefore contraindicated for use during pregnancy, and contraception is required beyond the end of treatment in women of child-bearing age.

Progression-free rate as the principal end-point for phase II trials in soft-tissue sarcomas

We have estimated progression-free rates (PFR) for various groups of soft-tissue sarcoma patients from our clinical trials database, to provide reference values for conducting phase II studies with PFR as the principal end-point. In 146 pretreated patients receiving an active agent, the PFR estimates were 39 and 14% at 3 and 6 months; with inactive regimens (234 patients), those estimates were 21 and 8% respectively. In 1154-non-pretreated patients, PFR estimates varied from 77% (synovial sarcoma) to 57% (malignant fibrous histiocytoma (MFH)) at 3 months, and from 56% (synovial sarcoma) to 38% (MFH) at 6 months. In 61 leiomyosarcomas from gastrointestinal origin, the corresponding figures were 44 and 30%, respectively. Consequently, for first-line therapy, a 6-month PFR of > or = 30-56% (depending on histology) can be considered as a reference value to suggest drug activity; for second-line therapy, a 3-month PFR of > or = 40% would suggest a drug activity, and < or = 20% would suggest inactivity.

Growth inhibition of human mammary carcinoma by liposomal hexadecylphosphocholine: Participation of activated macrophages in the antitumor mechanism

This study was undertaken to investigate the antitumor effect of liposomal hexadecylphosphocholine (L-HPC), a synthetic phospholipid encapsulated into multilamellar vesicles (MLV). The effect of these liposomes was tested in an orthotopic nude mouse model using the human mammary carcinomas MDA-MB 435 and 231. The main interest of the investigation was to study whether activated macrophages are substantially involved in the tumor growth inhibition mechanism. The growth of both MDA-MB 435 and 231 tumors in the mammary fat pad was significantly inhibited by a 14-day intraperitoneal therapy with L-HPC. The remaining tumors were shown to be heavily infiltrated with macrophages. In vitro studies of mPEM demonstrated a significant induction of macrophage-mediated tumor cytotoxicity (MMCTX) against the 2 cell lines by L-HPC. The L-HPC-mediated activation mechanism was characterized to be IL-6 and TNFalpha dependent but rather independent of IL-1alpha and nitric oxide (NO). NMA, a specific inhibitor of NO production, did not inhibit L-HPC-induced MMCTX. Furthermore, L-HPC was shown to upregulate the matrixmetalloproteinases MMP-9 and MMP-2 secretion into the supernatant. Considering cytokine release and production of collagenases, the L-HPC-induced macrophage activation cascade is assumed to be comparable with that of classical activators such as lipopolysaccharide (LPS) and interferon (IFN) gamma. As far as NO production is considered, the L-HPC activation mechanism differs from that caused by LPS and IFN gamma.

Clinical pharmacology of anticancer agents in relation to formulations and administration routes

In the past years, alternative administration routes and pharmaceutical formulations of anticancer agents have been investigated in order to improve conventional chemotherapy treatment. The impact of these adjustments on the pharmacokinetics and pharmacodynamics is discussed. A review of the literature shows many examples of alternative administration forms of anticancer agents with improved pharmacokinetics. Local administration routes have been investigated in order to reduce the systemic toxicity and to enhance the local efficacy of conventional chemotherapy. Oral administration of anticancer agents is preferred by patients for its convenience and its potential for outpatient treatment. In addition, oral administration facilitates a prolonged exposure to the cytotoxic agent. However, poor bioavailability and substantial interpatient variability are noted as limitations for oral chemotherapy. Increased tumour selectivity can also be achieved by the use of specific pharmaceutical formulations, such as liposomes and macromolecular drug conjugates. The composition of these formulations often determine the pharmacokinetic behaviour of the formulated drug. In conclusion, several alternative administration forms of anticancer agents have been designed in the past years, with the potential for improvement of conventional chemotherapy, however, more extensive clinical evaluation of these novel strategies is warranted to prove their real clinical value.

Phase II trial of topically applied miltefosine solution in patients with skin-metastasized breast cancer

Skin deposits from breast cancer can present serious therapeutic problems, especially when resistant to conventional therapy. Topical application of a cytotoxic drug may represent an attractive new treatment modality devoid of major systemic toxicity. Miltefosine was selected because of its efficacy in breast cancer models. A mixture of alkylated glycerols of various chain lengths and water was used as the pharmaceutical vehicle to dissolve and to further facilitate tissue penetration of miltefosine. In our Institute a phase II study was performed to determine the efficacy and tolerability of topically applied miltefosine in patients with cutaneous metastases from breast cancer. Thirty-three patients in total entered the trial. A 6% miltefosine solution was applied once daily in the first week and twice daily in the following weeks. The planned minimum treatment duration was 8 weeks. We found an overall response rate of 43% for 30 evaluable patients, composed of 23% complete response and 20% partial response. The median response duration was 18 weeks, range 8-68. Toxicity consisted mainly of localized skin reactions, which could be controlled by a paraffin-based skin cream and, where appropriate, by dose modification. No systemic toxicities were observed. We conclude that topical miltefosine is an effective treatment modality in patients with skin metastases from breast cancer.

Growth arrest vs direct cytotoxicity and the importance of molecular structure for the in vitro anti-tumour activity of ether lipids

A panel of 25 different lipid agents was evaluated for in vitro activity against HT29 human colon carcinoma and HL60 promyelocytic leukaemia cells by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The structure-activity relationships seen with this series, including those for four sets of positional or stereoisomers, indicate that specific receptor proteins are unlikely as targets for anti-tumour lipid (ATL) action. Additional data confirm the lack of involvement of the platelet-activating factor receptor in particular and suggest that metabolic stability is a most important determinant of ATL activity. More detailed studies, with 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine (ET18-OCH3) and (+/-)-2-(Hydroxy[tetrahydro-2-(octadecyloxy)methylfuran-2- yl]methoxyphosphinyloxy)-N,N,N,-trimethylethaniminium hydroxide (SRI 62-834), suggest three different modes of activity, depending on drug concentration and exposure time. Low doses of up to 5 microM in standard serum-containing medium cause population growth arrest after prolonged exposure. Growth arrest was associated with a leaky G2/M block as determined by flow cytometry. These effects are reversible. Intermediate concentrations (5-40 microM) were cytotoxic, causing a net reduction in cell numbers after 2-3 days. At even higher concentrations, all lipids caused rapid, direct membrane lysis. When the clonogenic assay was used to assess the effects of ATLs, most agents reduced colony formation at concentrations above 5 microM. However, some compounds proved stimulatory at nanomolar concentrations, suggesting that they might possess mitogenic properties. These results, particularly those concerning the concentration and time dependence, may be relevant to current clinical trials with ether lipids.

Increases in leucocyte and platelet counts induced by the alkyl phospholipid hexadecylphosphocholine

Hexadecylphosphocholine (HePC) is a new alkyl phospholipid that has been shown to have antitumour activity in vitro and in vivo. In vivo studies have shown absence of bone marrow toxicity at therapeutic doses. In addition, at the highest dosage group in rats, an increase in white blood cell counts (WBC) was observed. To study the presence of a similar phenomenon in man, frequent measurements of haematological parameters were performed in a series of phase II studies. 70 patients were treated with daily doses of 100-200 mg of the oral formulation of HePC. WBC and platelet counts were performed weekly. In a subgroup of 23 patients serum levels of haemopoietic growth factors were measured before and during treatment. A significant increase in WBC and platelet counts was seen in 74 and 73% of the patients, respectively. In 4 patients, bone marrow showed normal cellularity, and in 1 patient, bone marrow culture showed normal numbers and sizes of colony forming units. No abnormal levels or trends over time of cytokines were observed. We conclude that oral HePC induces an increase in WBC and platelet counts in the majority of those treated.

Antineoplastic activity of alkylphosphocholines (APC) in human breast carcinomas in vivo and in vitro; use of liposomes

This study examines the in vitro and in vivo activity of alkylphosphocholines (APC) in experimental human breast carcinomas. Three analogs, hexadecylphosphocholine (HPC), octadecylphosphocholine (OPC) and eicosanylphosphocholine (EPC) were investigated. Three hormone receptor negative cell lines were sensitive to all three APCs in vitro whereas the receptor positive MCF-7 line was more resistant. Sensitivity was seen in 4/6 hormone receptor negative tumors in vivo, with HPC being the most active analog. There were no antitumor effects in the four receptor positive models. The reasons for these differences in response between hormone receptor negative and -positive lines are not yet understood and require further study. Gastrointestinal toxicity and hemolysis, the major side effects of the APCs, were reduced by the use of liposomal preparations.