Phase II trial of liposome-encapsulated doxorubicin, cyclophosphamide, and fluorouracil as first-line therapy in patients with metastatic breast cancer

Redefining the Incidence and Profile of Fluoropyrimidine-Associated Cardiotoxicity in Cancer Patients: A Systematic Review and Meta-Analysis

Aim: The cardiac toxicity that occurs during administration of anti-tumor agents has attracted increasing concern. Fluoropyrimidines have been used for more than half a century, but their cardiotoxicity has not been well clarified. In this study, we aimed to assess the incidence and profile of fluoropyrimidine-associated cardiotoxicity (FAC) comprehensively based on literature data. Methods: A systematic literature search was performed using PubMed, Embase, Medline, Web of Science, and Cochrane library databases and clinical trials on studies investigating FAC. The main outcome was a pooled incidence of FAC, and the secondary outcome was specific treatment-related cardiac AEs. Random or fixed effects modeling was used for pooled meta-analyses according to the heterogeneity assessment. PROSPERO registration number: (CRD42021282155). Results: A total of 211 studies involving 63,186 patients were included, covering 31 countries or regions in the world. The pooled incidence of FAC, by meta-analytic, was 5.04% for all grades and 1.5% for grade 3 or higher. A total of 0.29% of patients died due to severe cardiotoxicities. More than 38 cardiac AEs were identified, with cardiac ischemia (2.24%) and arrhythmia (1.85%) being the most frequent. We further performed the subgroup analyses and meta-regression to explore the source of heterogeneity, and compare the cardiotoxicity among different study-level characteristics, finding that the incidence of FAC varied significantly among different publication decades, country/regions, and genders. Patients with esophagus cancer had the highest risk of FAC (10.53%), while breast cancer patients had the lowest (3.66%). The treatment attribute, regimen, and dosage were significantly related to FAC. When compared with chemotherapeutic drugs or targeted agents, such a risk was remarkably increased (χ2 = 10.15, p < 0.01; χ2 = 10.77, p < 0.01). The continuous 5-FU infusion for 3–5 consecutive days with a high dosage produced the highest FAC incidence (7.3%) compared with other low-dose administration patterns. Conclusions: Our study provides comprehensive global data on the incidence and profile of FAC. Different cancer types and treatment appear to have varying cardiotoxicities. Combination therapy, high cumulative dose, addition of anthracyclines, and pre-existing heart disease potentially increase the risk of FAC.

The Application of Nanoparticles in Diagnosis and Treatment of Kidney Diseases

Nanomedicine is currently showing great promise for new methods of diagnosing and treating many diseases, particularly in kidney disease and transplantation. The unique properties of nanoparticles arise from the diversity of size effects, used to design targeted nanoparticles for specific cells or tissues, taking renal clearance and tubular secretion mechanisms into account. The design of surface particles on nanoparticles offers a wide range of possibilities, among which antibodies play an important role. Nanoparticles find applications in encapsulated drug delivery systems containing immunosuppressants and other drugs, in imaging, gene therapies and many other branches of medicine. They have the potential to revolutionize kidney transplantation by reducing and preventing ischemia-reperfusion injury, more efficiently delivering drugs to the graft site while avoiding systemic effects, accurately localizing and visualising the diseased site and enabling continuous monitoring of graft function. So far, there are known nanoparticles with no toxic effects on human tissue, although further studies are still needed to confirm their safety.

Pericardial Effusion during Proton Therapy in a Patient with Chemorefractory Hodgkin Lymphoma

We present a case of recurrent pericardial effusion presenting during proton therapy in a 24-year-old female receiving mediastinal treatment for classical Hodgkin lymphoma. Pericardial effusion is typically considered an event accompanying lymphoma diagnosis or as a subacute or late effect of radiotherapy. Rarely has it been described as occurring during radiation treatment with photon-based radiotherapy, let alone proton therapy. It is unclear what underlying cause triggered recurrent effusion in this patient. Identifying and managing pericardial effusion during treatment delivery is important to consider as it may affect radiation dosimetry, particularly with proton therapy. Doing so will help ensure patients receive optimal treatment and minimize the risks of morbidity and mortality.

From Conventional to Stealth Liposomes a new Frontier in Cancer Chemotherapy

Many attempts have been made to achieve good selectivity to targeted tumor cells by preparing specialized carrier agents that are therapeutically profitable for anticancer therapy. Among these, liposomes are the most studied colloidal particles thus far applied in medicine and in particular in antitumor therapy. Although they were first described in the 1960s, only at the beginning of 1990s did the first therapeutic liposomes appear on the market. The first-generation liposomes (conventional liposomes) comprised a liposome-containing amphotericin B, Ambisome (Nexstar, Boulder, CO, USA), used as an antifungal drug, and Myocet (Elan Pharma Int, Princeton, NJ, USA), a doxorubicin-containing liposome, used in clinical trials to treat metastatic breast cancer. The second-generation liposomes (“pure lipid approach”) were long-circulating liposomes, such as Daunoxome, a daunorubicin-containing liposome approved in the US and Europe to treat AIDS-related Kaposi's sarcoma. The third-generation liposomes were surface-modified liposomes with gangliosides or sialic acid, which can evade the immune system responsible for removing liposomes from circulation. The fourth-generation liposomes, pegylated liposomal doxorubicin, were called “stealth liposomes” because of their ability to evade interception by the immune system, in the same way as the stealth bomber was able to evade radar. Actually, the only stealth liposome on the market is Caelyx/Doxil (Schering-Plough, Madison NJ, USA), used to cure AIDS-related Kaposi's sarcoma, resistant ovarian cancer and metastatic breast cancer. Pegylated liposomal doxorubicin is characterized by a very long-circulation half-life, favorable pharmacokinetic behavior and specific accumulation in tumor tissues. These features account for the much lower toxicity shown by Caelyx in comparison to free doxorubicin, in terms of cardiotoxicity, vesicant effects, nausea, vomiting and alopecia. Pegylated liposomal doxorubicin also appeared to be less myelotoxic than doxorubicin. Typical forms of toxicity associated to it are acute infusion reaction, mucositis and palmar plantar erythrodysesthesia, which occur especially at high doses or short dosing intervals. Active and cell targeted liposomes can be obtained by attaching some antigen-directed monoclonal antibodies (Moab or Moab fragments) or small proteins and molecules (folate, epidermal growth factor, transferrin) to the distal end of polyethylene glycol in pegylated liposomal doxorubicin. The most promising therapeutic application of liposomes is as non-viral vector agents in gene therapy, characterized by the use of cationic phospholipids complexed with the negatively charged DNA plasmid. The use of liposome formulations in local-regional anticancer therapy is also discussed. Finally, pegylated liposomal doxorubicin containing radionuclides are used in clinical trials as tumor-imaging agents or in positron emission tomography.

Liposomal Doxorubicin in Breast Cancer

Drug-delivery carriers represent an important step in the development of targeted therapy. Encapsulation of drug into liposomes represents such a carrier, and helps to minimize side effects of conventional doxorubicin by improving the tumor-specific biodistribution profile. We review the development of the two liposomal doxorubicin formulations, pegylated liposomal doxorubicin and liposomal-encapsulated doxorubicin citrate from reconstitution and comparative pharmacokinetics to pivotal Phase III trials, with special emphasis in breast cancer. The relative differences in the toxicity profile can be attributed to their differences in the liposomal formulations. Areas of special interest include the reduction in cardiac toxicities and the improved efficacy, such as in the treatment of ovarian cancer. These improvements have also increased the potential of these liposomal formulations of doxorubicin for combination and sequencing with other biological and cytotoxic agents for clinical benefit.

First-line chemotherapy with liposomal doxorubicin plus cyclofosfamide in metastatic breast cancer: a case report of early and prolonged response

The treatment choice for metastatic breast cancer should consider the appropriate balance between efficacy and toxicity of the therapy. We discuss a clinical case with an early response and prolonged to liposomal anthracyclines-based chemotherapy, without cardiotoxicity, enhancing the evidence of safety of liposomal formulation to prevent heart damage. Moreover, the case seems to be of interest for the role of 18F-FDG-PET in clinical response assessment: an early decrease of the standardized uptake value value, even before conventional imaging evaluation, is highly predictive for prolonged clinical response.

Development of the novel PEG-PE-based polymer for the reversible attachment of specific ligands to liposomes: synthesis and in vitro characterization

Surface grafting of liposomes with the wide variety of ligands including antibodies and other proteins is a promising approach for targeted delivery of therapeutics. In this paper, we describe a simple method of synthesizing a hydrazine-functionalized poly(ethylene glycol)-phosphatidylethanolamine (PEG-PE)-based amphiphilic polymer which can conjugate a variety of ligands via a reversible, pH-cleavable bond. In this method, the targeting ligand is attached to the distal end of the PEG chain, which facilitates its easy access to the targeted site of interaction. The reversible attachment of targeting ligands is useful especially in multifunctional liposomal systems, whereafter successfully performing the function of targeting to the specific site, the bulky ligands, such as proteins or antibodies, are cleaved off in response to an environmental stimulus to expose some other functionalities such as ligands for intracellular penetration or organelle-specific targeting. To investigate the applicability of the protocol, the model ligands monoclonal antinucleosome antibody 2C5 and antimyosin antibody 2G4, and glycoproteins concanavalin A (Con-A) and avidin were conjugated to the synthesized polymer and incorporated into liposomes. In vitro assays including biochemical, enzyme-linked immunosorbent, fluorescence microscopy, and flow cytometry were used to confirm three key characteristics of the modified and/or liposome-attached proteins: successful conjugation of the targeting ligands to the polymer, preservation of specific activity of the ligands after the conjugation and liposome attachment, and the facile pH-sensitive ligand detachment. Monoclonal antibody 2C5 and 2G4, immobilized on the liposome surface, retained their binding affinity to corresponding antigens as confirmed by ELISA. The Con A-bearing liposomes showed significantly higher agglutination in the presence of its substrate mannan compared to plain liposomes (PL) and avidin-functionalized liposomes bound specifically with biotin-agarose. The study on the pH-dependence showed that almost 80% of the hydrazone bond was cleaved after rather brief preincubation of the immunoliposomes at pH 5 for 0.5 to 1 h. Fluorescence microscopy and flow cytometry analysis of cancer cells (HeLa and MCF-7) treated with cancer cell-specific targeting ligand mAb 2C5-bearing liposomes showed enhanced cellular binding. Studies at low pH clearly confirmed the easy cleavability of the targeting ligand from the liposomes resulting in significantly less or virtually no cellular association.

Cardiotoxicity of anticancer treatments: what the cardiologist needs to know

Cardiotoxicity of anticancer treatments has become an increasingly important clinical problem faced by cardiologists. Left ventricular systolic dysfunction and heart failure generate the most concern, but clinical features and prognosis vary considerably depending on the causative agent. Anthracycline-related cardiomyopathy differs fundamentally from effects associated with newer targeted agents, such as trastuzumab. Other forms of cardiovascular disease that occur as a result of cancer treatment include hypertension, thromboembolic disease, pericardial disease, arrhythmia, and myocardial ischemia. The approach to cardiovascular disease in patients with cancer is often different from that in the general population, not only because of distinct underlying mechanisms and clinical features of their heart disease, but also because of the potential ongoing need for additional cancer treatment as well as the altered duration of anticipated survival. In an effort to maximize both quality of life and survival, cardiologists and oncologists should collaborate with the aim of balancing the risks of cardiotoxicity with the benefits of oncologic therapy.

A historical perspective of anthracycline cardiotoxicity

Anthracyclines remain important agents in the treatment of solid and hematological malignancy. Early experience with these drugs reported cardiac failure as an adverse event. Later, clinical recognition of cell injury at the time of administration was appreciated. This article explores the evolution of our understanding about anthracycline-associated cardiotoxicity, including the various strategies for the pretreatment assessment of patients for whom anthracyclines are contemplated, the frustrations associated with the lack of specific tests that could identify patients at risk of developing problems with their next 1 or 2 cycles, the concept of balancing oncologic benefit with cardiac risk in the treatment of cancer patients, and the newer strategies for reducing the potentially devastating complications of the treatment of malignant disease with anthracyclines.

Impact of liposomal doxorubicin-based adjuvant chemotherapy on autonomy in women over 70 with hormone-receptor-negative breast carcinoma: A French Geriatric Oncology Group (GERICO) phase II multicentre trial

RATIONALE

Breast cancer is a disease of ageing. Functional independence in elderly patients, measured with the Katz activities of daily living (ADL) scale, predicts overall survival and the need for welfare support. Few prospective studies have examined the feasibility of adjuvant chemotherapy and its impact on autonomy in women over 70 years of age with high-risk breast cancer. This multicentre phase II trial was designed to assess the impact of adjuvant anthracycline-based chemotherapy on these patients' autonomy.

DESIGN AND METHODS

In a two-stage Fleming design, women aged ≥70 years with histologically proven hormone-receptor-negative early breast cancer and a significant risk of recurrence (pN+ or "high risk" pN0) received 4 cycles of nonpegylated liposomal doxorubicin 60 mg/m(2) and cyclophosphamide 600 mg/m(2) every 3 weeks postoperatively, on an outpatient basis. The primary endpoint was the change in the ADL score during chemotherapy. Secondary endpoints include comprehensive geriatric, quality-of-life and acceptability assessments, tolerability, and long-term outcome. The results for the primary endpoint and other scales at completion of adjuvant chemotherapy are reported here, while long-term follow-up is not yet complete.

RESULTS

Forty patients (median age 75 [70-82]) were enrolled between February 2006 and November 2007. Chemotherapy had no deleterious impact on ADL, cognition, mental status, or the frequency of comorbidities. In contrast, the number of patients at risk of malnutrition, based on the Mini Nutritional Assessment, more than doubled between baseline and the end of chemotherapy, rising from 15% to 38%. Quality-of-life deteriorated in terms of social and role functioning, likely owing to fatigue, loss of appetite, nausea and vomiting. Treatment acceptability was good. The main adverse effect was neutropenia, 15% of the patients experiencing febrile neutropenia. No cardiac toxicity or toxic deaths occurred.

CONCLUSION

This study demonstrates the feasibility of an adjuvant chemotherapy regimen combining nonpegylated liposomal doxorubicin and cyclophosphamide in fit elderly women <85 years with breast cancer. Although chemotherapy had an impact on social and role functioning, autonomy was not impaired and toxicity was acceptable. Special attention should be paid to nutritional status before and after treatment.

A phase I clinical and pharmacokinetic study (LIPOTEC - GP PHARM/DOXO 01) of a new liposomal doxorubicin given as 3-week schedule in patients with solid tumors

As a dose-finding phase I study of a new liposomal formulation of doxorubicin (LipD), patients (n = 39; median age: 60 years; range, 41-75; median ECOG performance status, 1; range, 0-2) with refractory cancer had a starting dose of LipD administered at 30 mg/m(2) as a 1-hour intravenous infusion. Cycle duration was 21 days. At the recommended dose (RD), patients received a first cycle of nonliposomal doxorubicin (non-LipD) to evaluate intrapatient pharmacokinetic differences between non-LipD and LipD. The most frequent diagnosis was head and neck tumor (7 patients). Tolerance and safety of dose levels of 30, 40, 50, 60, 70, 80, and 90 mg/m(2) were evaluated. A total of 131 cycles were administered (median per patient, 3; range, 1-6). Of the 39 patients, 8 completed the planned six cycles. Febrile neutropenia was dose limiting and defined the toxic dose of LipD as 70 mg/m(2). Other significant toxicities included asthenia (G2: 31%; G3: 8%), neutropenia (G3: 35%; G4: 29%), thrombopenia (G3: 15%; G4: 2%), anemia (G1-G2: 67%; G3-G4: 5%), mucositis (G1-G2: 32%, G3: 4%), and acute allergic reactions (G1-G2: 36%). Comparison of pharmacokinetic profiles of non-LipD and LipD showed that higher exposure was achieved with LipD. Stable disease was observed in 14 patients. We conclude that the LipD regimen, given as a 1-hour infusion every 3 weeks, is well tolerated and has a favorable pharmacokinetic profile. The recommended dose is 70 mg/m(2) with prophylactic antihistamines and corticoids to preempt allergic reaction.

Role of liposomal anthracyclines in breast cancer

Anthracyclines are among the most effective drugs for patients with breast cancer. Their use, however, has been limited by associated toxic effects, including myelosuppression, alopecia, nausea and vomiting, stomatitis, and most importantly, cardiotoxicity. Liposomal anthracyclines were developed to increase the therapeutic index of conventional anthracyclines by maintaining antitumor efficacy while improving the safety profile. There are currently two liposomal formulations available for treatment of advanced disease: a not pegylated liposomal doxorubicin and a pegylated liposomal doxorubicin. This review will focus on both liposomal formulations of doxorubicin which are approved in Europe and Canada for use in patients with metastatic breast cancer.

Liposome-encapsulated doxorubicin citrate in previously treated recurrent/metastatic gynecological malignancies

The aim of this study was to evaluate the safety and efficacy of liposome-encapsulated doxorubicin citrate (LEDC) in patients affected by recurrent/metastatic gynecological malignancies scheduled for palliative chemotherapy. Inclusion criteria were proven recurrent/advanced gynecological neoplasms, measurable/assessable disease, adequate organ function, left ventricular ejection fraction >50% as determined by echocardiography, informed consent. LEDC was administered intravenously over 1 h at the dose of either 75 mg/m(2) or 60 mg/m(2) (every 3 weeks until disease progression or toxicity prohibiting further therapy). From May 2003 to September 2005, 36 patients were enrolled. Primary disease was ovarian, endometrial, and cervical cancers in 15 (42%), 11 (30%), and 10 (28%) patients, respectively. LEDC was employed as third- or fourth-line chemotherapy in 25 (70%) and 11 (30%) patients, respectively. The median number of courses of LEDC received was 3 (range 2-9). Six patients (17%) achieved a partial response to treatment lasting 27 weeks and 10 patients (28%) experienced stable disease lasting 18 weeks. The predominant toxicity was hematological, especially neutropenia. Among patients receiving a dose of 75 mg/m(2), two (11%) suspended therapy for febrile neutropenia, and nine (50%) required a dose reduction of 25%. As a result, the next 18 patients were treated at a reduced dose (60 mg/m(2)) of LEDC. Severe neutropenia (G3-G4) was significantly less common in this group (61% versus 22%; P= 0.04). LEDC has shown antineoplastic activity in previously treated recurrent/metastatic gynecological cancer patients and the toxicity profile could be considered acceptable at a 60 mg/m(2) dosage.

Monitoring chemotherapy-induced cardiotoxicity: role of cardiac nuclear imaging

Cardiotoxicity may result from a range of chemotherapeutic agents. The prevalence of cardiotoxicity from certain cytotoxic agents is reported to be significantly high. In addition to serious side effects and increased long-lasting morbidity and mortality, dose limitation and suboptimal usage is an important adverse effect. Nuclear cardiac imaging has played a quintessential and important role in identifying patients at risk and in the prevention and reduction of cardiac injury resulting from cytotoxic agents. Despite exploring a number of other diagnostic imaging or biochemical tools for identification of cardiac injury, nuclear cardiac imaging in the form of radionuclide angiocardiography continues to be the most suitable and cost-effective tool for reducing the prevalence of cases of cardiac dysfunction resulting from chemotherapy. This article reviews the prevalence, mechanisms, and prevention strategies for cardiotoxicity associated with some of the commonly known cytotoxic agents and the role of nuclear cardiac imaging in its monitoring and prevention, along with recent advances in this area.

Metastatic breast cancer: an updating

This article reports on recent advances on metastatic breast cancer. Detection, prognostic factors, predictors of response to therapy and therapy, with particular regard to targeted therapies, were examined.

DETECTION

Unlike current guidelines that yet do not routinely recommend intensive clinical-instrumental post-operative follow-up of breast cancer patients, relatively large data collected in the last decades have shown that an intensive post-operative follow-up with 'dynamic evaluation' of a suitable tumour marker panel precedes a few months as average the clinical and/or instrumental sign of a pending relapse in most relapsed patients and largely limits the use of the common instrumental examinations.

PROGNOSIS AND THERAPY PREDICTORS

Disease-free interval (DFI)<or=24 months, adjuvant chemotherapy, liver and distant soft tissue involvement or DFI>24 months and disease confined to bony skeleton are prognostic factors more often correlated with relatively poor or prolonged survival, respectively. Estrogen receptor (ER) expression in primary tumour and at the relapse correlates strongly with response to salvage hormone therapy and data from large trials showed that 38-59% of ER and/or PR+ post-menopausal patients had clinical benefit from first line tamoxifen or aromatase inhibitors. An inverse correlation of ER with epidermal growth factor receptor (EGFR) has been found. The co-expression of HER-2/neu and/or elevated serum HER-2/neu protein level were associated with a low rate and shorter duration of response of ER+ patients to first line hormone therapy. Accordingly, ER-EGFR- compared with ER-EGFR+ tumours are usually more responsive to endocrine therapy. High class III beta-tubulin expression or fall in insulin-like growth factor binding protein-3 (IGFBP-3) from baseline levels have been found to significantly predict resistance to chemotherapeutic agents.

THERAPY

Liposomes as carrier of doxorubicin (Caelix, Evacet, Myocet) is one approach to decrease the anthracycline-related cardiac toxicity. Weekly paclitaxel or docetaxel and oral formulation of vinorelbine and 5-fluorouracil (5-FU) (capecitabine) provide new effective and well tolerated options that reach greater dose intensity and cumulative dose than with the conventional schedules. As to the so called 'tailored' or targeted therapies, the more potent and highly selective third generation of aromatase inhibitors (letrozole, anastrozole, exemestane) targeting ER+ tumours by estrogen deprivation, challenge tamoxifen as current standard first line therapy in postmenopausals. One pilot study showed that stimulation of cellular immunity by the addition of beta-interferon-interleukin-2 sequence in patients on clinical benefit on first line tamoxifen significantly prolonged median overall survival (OS) and duration of response compared to that observed in similar patients only treated with tamoxifen. Trastuzumab, a humanised monoclonal antibody to extracellular domain of HER-2, plus conventional chemotherapy has become a standard of care for women with overexpressing HER-2 tumours. Bevacizumab is a recombinant humanised monoclonal antibody to vascular endothelial growth factor (VEGF) that in refractory metastatic breast cancer doubled the response rate of capecitabine although it did not affect survival. Finally, the so called 'oligometastatic' and a few stage IV diseases are conditions amenable to be rendered with no evidence of disease (NED) after local surgery and/or radiation. In both, as well as in complete responders to chemotherapy, minimal residual disease (m.r.d.) likely continues to be present. Recent data suggest that 'biological' therapy (immunomodulators and/or retinoids with or without hormone therapy), might be suitable to be successfully tested in these patients as maintenance treatment given soon after local intervention or chemotherapy.

Phase I trial of liposomal encapsulated doxorubicin (Myocet; D-99) and weekly docetaxel in advanced breast cancer patients

BACKGROUND

We conducted a phase I trial to determine the safety and maximum tolerated dose (MTD) of non-pegylated liposome-encapsulated doxorubicin (Myocet; D-99) administered with weekly docetaxel in metastatic breast cancer (MBC) patients.

PATIENTS AND METHODS

Twenty-one patients with no prior chemotherapy for MBC received D-99 (60 or 50 mg/m2) intravenously (i.v.) on day 1 and escalating doses of docetaxel (25, 30 and 35 mg/m2 i.v. on days 1 and 8 in cohorts of three to six patients. Treatment cycles were repeated every 21 days for a maximum of six cycles.

RESULTS

The maximum tolerated dose (MTD) was 50 mg/m2 of D-99 in combination with 25 mg/m2 of weekly docetaxel. The most common grade 4 toxicity was neutropenia that occurred in 42 (41%) of treatment cycles, with 10 hospitalizations for febrile neutropenia. Serious protocol-defined cardiac events occurred in three (14%) patients, with two (10%; 95% confidence interval [CI] 1% to 30%) developing congestive heart failure (CHF) after a total cumulative anthracycline dose (adjuvant doxorubicin + D-99) of 540 mg/m2.

CONCLUSIONS

D-99 in combination with weekly docetaxel, at the doses and schedule as administered in this trial, is not recommended for phase II testing. Additional trials, using different doses and schedules, are required to evaluate the potential side-effects and efficacy of D-99 and docetaxel.

Phase III trial of liposomal doxorubicin and cyclophosphamide compared with epirubicin and cyclophosphamide as first-line therapy for metastatic breast cancer

OBJECTIVE

To ascertain the efficacy and tolerability of non-pegylated liposomal doxorubicin (Myocet) and epirubicin combined with cyclophosphamide in the first-line treatment of patients with metastatic breast cancer.

METHODS

One hundred and sixty anthracycline-naïve metastatic breast cancer patients were randomised to receive Myocet (M; 75 mg/m(2)) or epirubicin (E; 75 mg/m(2)) in combination with cyclophosphamide (C; 600 mg/m(2)), every 3 weeks for up to eight cycles.

OUTCOME MEASURES

Response (overall response = complete + partial response rates), time to disease progression, overall survival and cardiac function (left ventricular ejection fraction).

RESULTS

Overall response rates were 46% and 39% for MC and EC treatment, respectively (P=0.42). MC was superior to EC with respect to median time to treatment failure (5.7 versus 4.4 months; P=0.01) and median time to disease progression (7.7 versus 5.6 months; P=0.02). Median survival times were 18.3 and 16.0 months for MC and EC, respectively (P=0.504). Unsurprisingly, given an equimolar comparison, neutropenia and stomatitis/mucositis were significantly more common in patients who received MC. However, there was less injection site toxicity with MC. Both treatments showed a low incidence of cardiotoxicity.

CONCLUSION

Myocet appears to be an acceptable alternative to epirubicin as a first-line treatment for patients with metastatic breast cancer because it combines the dose-effect reliability of doxorubicin with the level of safety provided by epirubicin.

Glucuronate-Modified, Long-Circulating Liposomes for the Delivery of Anticancer Agents

Liposomes are useful as drug carriers in drug delivery systems, especially for drugs with severe side effects such as antitumor agents. The conventional formulations of liposomes are opsonized by plasma proteins in the bloodstream and trapped in the reticuloendothelial system (RES). Therefore, liposomes with reduced opsonization are expected to have prolonged circulation and to accumulate in tumor tissue due to the leaky endothelium of the tissue. To avoid RES trapping of liposomes, two approaches have been considered. Liposomes may mimic cells circulating in the blood to escape host recognition as foreign substances, or liposomes may be covered with a hydrophilic barrier to escape recognition. For the latter purpose, poly(ethylene glycol) is widely used. For the former purpose, here we focus on the characteristics, in vivo trafficking, and usage in cancer therapy of glucuronate-modified liposomes. Glucuronate-modified liposomes bind to a lower extent to macrophage-like cells in vitro and passively accumulate in tumor tissue evaluated by a technique using positron emission tomography. Glucuronate-modified liposomes with extended circulation are useful for delivering anticancer agents to tumors and reducing the toxic side effects of the agents.

The role of the liposomal anthracyclines and other systemic therapies in the management of advanced breast cancer

For patients whose breast cancers are not responsive to endocrine therapy, there are a large number of cytotoxic drugs that will induce a response. In spite of the introduction of new, very active drugs such as the taxanes, vinorelbine, capecitabine, gemcitabine, and trastuzumab, the anthracyclines are still as active as any--and more active than most--drugs used to treat breast cancer. Their inclusion in combinations to treat early and advanced disease prolongs survival. However, they cause nausea, vomiting, alopecia, myelosuppression, mucositis, and cardiomyopathies. There is no evidence that increasing the dose of conventional anthracyclines or any other of the cytotoxics beyond standard doses will improve outcomes. Schedule may be more important than dose in determining the benefit of cytotoxics used to treat breast cancer. Weekly schedules and continuous infusions of 5-fluorouracil and doxorubicin may have some advantages over more intermittent schedules. Liposomal formations of doxorubicin reduce toxicity, including cardiotoxicity; theoretically they should also be more effective because of better targeting of tumor over normal tissues. Both pegylated liposomal doxorubicin (Doxil/Caelyx [PLD]) and liposomal doxorubicin (Myocet [NPLD]) appeared to be as effective as conventional doxorubicin and much less toxic in multiple phase II and phase III studies. PLD has been evaluated in combinations with cyclophosphamide, the taxanes, vinorelbine, gemcitabine, and trastuzumab, and NPLD has been evaluated in combination with cyclophosphamide and trastuzumab. Both liposomal anthracyclines are less cardiotoxic than conventional doxorubicin. The optimal dose of PLD is lower than that of conventional doxorubicin or NPLD. Patients treated with PLD have almost no alopecia, nausea, or vomiting, but its use is associated with stomatitis and hand-foot syndrome, which can be avoided or minimized with the use of proper dose-schedules. In contrast, the optimal dose-schedule of NPLD is nearly identical to that of conventional doxorubicin. The toxicity profile of NPLD is similar to that of conventional doxorubicin, but toxicities are less severe and NPLD is better tolerated than conventional doxorubicin at higher doses.

Liposomal anthracyclines: adjuvant and neoadjuvant therapy for breast cancer

Conventional anthracyclines, particularly doxorubicin, have played an important role in the treatment of patients with breast cancer for many decades. Conventional doxorubicin has shown excellent antitumor activity in the metastatic, neoadjuvant, and adjuvant settings. However, its clinical utility is limited due to acute and chronic toxicities, particularly cardiotoxicity, myelosuppression, nausea and vomiting, and alopecia. Liposomal doxorubicin formulations (liposomal doxorubicin [D-99] and pegylated liposomal doxorubicin) currently under investigation for the treatment of breast cancer have demonstrated similar efficacies and favorable toxicity profiles compared with conventional doxorubicin in patients with metastatic breast cancer. These agents have also shown efficacy and tolerability in several small studies as neoadjuvant therapy in patients with locally advanced breast cancer. While there are currently no studies with liposomal doxorubicin or pegylated liposomal doxorubicin as adjuvant therapy, their demonstrated activities and tolerabilities in the metastatic and neoadjuvant settings provide the rationale for the future study of these agents in adjuvant therapy for patients with early-stage breast cancer.

In Vitro and in Vivo Characterization of Doxorubicin and Vincristine Coencapsulated within Liposomes through Use of Transition Metal Ion Complexation and pH Gradient Loading

PURPOSE

There is an opportunity to augment the therapeutic potential of drug combinations through use of drug delivery technology. This report summarizes data obtained using a novel liposomal formulation with coencapsulated doxorubicin and vincristine. The rationale for selecting these drugs is due in part to the fact that liposomal formulations of doxorubicin and vincristine are being separately evaluated as components of drug combinations.

EXPERIMENTAL DESIGN

Doxorubicin and vincristine were coencapsulated into liposomes using two distinct methods of drug loading. A manganese-based drug loading procedure, which relies on drug complexation with a transition metal, was used to encapsulate doxorubicin. Subsequently the ionophore A23187 was added to induce formation of a pH gradient, which promoted vincristine encapsulation.

RESULTS

Plasma elimination studies in mice indicated that the drug:drug ratio before injection [4:1 doxorubicin:vincristine (wt:wt ratio)] changed to 20:1 at the 24-h time point, indicative of more rapid release of vincristine from the liposomes than doxorubicin. Efficacy studies completed in MDA MB-435/LCC6 tumor-bearing mice suggested that at the maximum tolerated dose, the coencapsulated formulation was therapeutically no better than liposomal vincristine. This result was explained in part by in vitro cytotoxicity studies evaluating doxorubicin and vincristine combinations analyzed using the Chou and Talalay median effect principle. These data clearly indicated that simultaneous addition of vincristine and doxorubicin resulted in pronounced antagonism.

CONCLUSION

These results emphasize that in vitro drug combination screens can be used to predict whether a coformulated drug combination will act in an antagonistic or synergistic manner.

Current Status of Liposomal Anthracycline Therapy in Metastatic Breast Cancer

Doxorubicin is a mainstay for the treatment of metastatic breast cancer (MBC); however, its use is limited by toxicity, particularly cardiotoxicity. Novel drug delivery systems using liposomes have been developed to maintain the clinical utility of conventional doxorubicin while minimizing cardiotoxicity. Three liposomal anthracyclines have been developed: liposomal daunorubicin, nonpegylated liposomal doxorubicin, and pegylated liposomal doxorubicin. Liposomal daunorubicin, currently approved in the United States for the treatment of AIDS-related Kaposi sarcoma, has shown preliminary activity in MBC in a phase I trial; further investigation is ongoing. Nonpegylated liposomal doxorubicin, which is not available in the United States, has demonstrated activity similar to that of conventional doxorubicin (both as a single agent and in combinations). Pegylated liposomal doxorubicin has demonstrated activity in phase II and III trials when used alone or in combination with other chemotherapeutic agents in patients with MBC. It is currently approved in the United States and Europe for AIDS-related Kaposi sarcoma and platinum/paclitaxel-refractory ovarian carcinoma; in Europe and Canada, it is also approved as monotherapy for MBC. In addition, accumulating evidence suggests that the combination of liposomal anthracyclines (pegylated and nonpegylated) and trastuzumab is active, with acceptable toxicity. Based on these encouraging experiences, randomized clinical trials are ongoing or planned to further assess the therapeutic potential of pegylated liposomal doxorubicin as a single agent and in combination with other chemotherapeutic agents and targeted agents, such as trastuzumab, for MBC.

Liposomal Anthracyclines in Metastatic Breast Cancer: Clinical Update

Anthracyclines are a mainstay of therapy for patients with metastatic breast cancer. However, their use has been limited by associated toxicities, including myelosuppression, alopecia, nausea and vomiting, stomatitis, and most importantly, cardiotoxicity. Liposomal anthracyclines were developed to increase the therapeutic index of conventional anthracyclines by maintaining antitumor efficacy while improving the safety profile. There are currently three liposomal formulations: liposomal daunorubicin, liposomal doxorubicin (D-99), and pegylated liposomal doxorubicin. Only one phase I study has been conducted with liposomal daunorubicin for metastatic breast cancer. Liposomal doxorubicin has shown comparable efficacy with conventional doxorubicin and less toxicity. Pegylated liposomal doxorubicin is the most widely studied of the liposomal anthracyclines and has demonstrated similar efficacy to conventional doxorubicin and a better safety profile, including significantly less cardiotoxicity, in patients with metastatic breast cancer. Pegylated liposomal doxorubicin has shown efficacy as a single agent and in combination with many agents, including cyclophosphamide, paclitaxel, docetaxel, and gemcitabine, with response rates ranging from 33%-75%. Growing evidence supports the use of pegylated liposomal doxorubicin as first-line treatment for patients with metastatic breast cancer, owing to its antitumor activity in both anthracycline-naïve patients and in patients with previous anthracycline exposure.

Congestive heart failure in patients treated with doxorubicin: a retrospective analysis of three trials

BACKGROUND

Doxorubicin is a highly effective and widely used cytotoxic agent with application that is limited by cardiotoxicity related to the cumulative dose of the drug. A large-scale study that retrospectively evaluated the cardiotoxicity of doxorubicin reported that an estimated 7% of patients developed doxorubicin-related congestive heart failure (CHF) after a cumulative dose of 550 mg/m(2). To assess whether this estimate is reflective of the incidence in the broader clinical oncology setting, the authors evaluated data from three prospective studies to determine both the incidence of doxorubicin-related CHF and the accumulated dose of doxorubicin at which CHF occurs.

METHODS

A group of 630 patients who were randomized to a doxorubicin-plus-placebo arm of three Phase III studies, two studies in patients with breast carcinoma and one study in patients with small cell lung carcinoma, were included in the analysis.

RESULTS

Thirty-two of 630 patients had a diagnosis of CHF. Analysis indicated that an estimated cumulative 26% of patients would experience doxorubicin-related CHF at a cumulative dose of 550 mg/m(2). Age appeared to be an important risk factor for doxorubicin-related CHF after a cumulative dose of 400 mg/m(2), with older patients (age > 65 years) showing a greater incidence of CHF compared with younger patients (age < or = 65 years). In addition, > 50% of the patients who experienced doxorubicin-related CHF had a reduction < 30% in left ventricular ejection fraction (LVEF) while they were on study.

CONCLUSIONS

Doxorubicin-related CHF occurs with greater frequency and at a lower cumulative dose than previously reported. These findings further indicate that LVEF is not an accurate predictor of CHF in patients who receive doxorubicin.

Folate receptor-targeted liposomes as vectors for therapeutic agents

The folate receptor is a cell surface protein that has recently been identified as a tumor marker, due to its differential overexpression in several malignancies. Current research indicates that folate can be covalently attached to the surface of liposomes to mediate their selective internalization by tumor cells through the folate receptor-mediated endocytic pathway. Optimized liposome formulations, characterized by improvements in drug loading, extended residence times in the circulation and improved drug release, have been developed to improve the biodistribution of therapeutic molecules. Theoretically, folate receptor-targeting can be combined with liposome encapsulation to synergistically affect disease outcome by enhancing the delivery of chemotherapeutic agents to neoplastic cells, while reducing systemic toxicities to normal tissues. The purpose of this chapter is to characterize the components of folate receptor-targeted liposomes, and summarize their applications in gene and drug delivery.

Difficult cases in heart failure: chemotherapy-related cardiomyopathy--all that glitters is not gold

As long-term morbidity with chemotherapeutic exposure becomes a clinical reality, the development of cardiomyopathy with heart failure is rapidly growing. The type of chemotherapy agent, dose, rate of administration, use of combination chemotherapy, and concomitant radiation therapy are major factors that define the propensity to cardiotoxicity. Chemotherapy-related cardiomyopathy is multifactorial in origin and requires a diligent etiologic survey to arrive at the appropriate diagnosis. A contemporary discussion of chemotherapy-related cardiomyopathy with particular emphasis on the pathogenesis and ameliorative targets of this unique clinical disorder are described in this report.

Liposomally targeted cytotoxic drugs for the treatment of cancer

Phospholipid spherules composed of lipid bilayer membranes entrapping a central aqueous core were first described more than 30 years ago (Bangham et al 1965). The term liposome was coined in 1968 (Sessa & Weissmann 1968) and the first suggestions that these vesicles might have potential as vehicles for targeted drug delivery for a range of diseases, including cancer, appeared shortly afterwards (Gregoriades et al 1974; Gregoriades 1976a, b). However, the process of turning this expectation into a clinical reality has suffered a number of setbacks and has taken more than a quarter of a century. In the process, new types of liposomes with favourable in-vivo pharmacokinetics and biodistribution patterns have been generated (Lasic & Papahadjopoulos 1995). Many of these preparations have been subjected to extensive examination and an increasing number of agents have entered clinical trials. In this review, we will trace the development of those liposomes that are currently undergoing (or are about to undergo) clinical evaluation.

Liposomal daunorubicin overcomes drug resistance in human breast, ovarian and lung carcinoma cells

Multi-drug resistance due in part to membrane pumps such as P-glycoprotein (Pgp) is a major clinical problem in human cancers. We tested the ability of liposomally-encapsulated daunorubicin (DR) to overcome resistance to this drug. A widely used breast carcinoma cell line originally selected for resistance in doxorubicin (MCF7ADR) was 4-fold resistant to DR compared to the parent MCF7 cells (IC50 79 nM vs. 20 nM). Ovarian carcinoma cells (SKOV3) were made resistant by retroviral transduction of MDR1 cDNA and selection in vinblastine. The resulting SKOV3MGP1 cells were 130-fold resistant to DR compared to parent cells (IC50 5700 nM vs. 44 nM). Small-cell lung carcinoma cells (H69VP) originally selected for resistance to etoposide were 6-fold resistant to DR compared to H69 parent cells (IC50 180 nM vs. 30 nM). In all three cases, encapsulation of DR in liposomes as Daunoxome (Gilead) did not change the IC50 of parent cells relative to free DR. However, liposomal DR overcame resistance in MCF7ADR breast carcinoma cells (IC50 20 nM), SKOV3MGP1 ovarian carcinoma cells (IC50 237 nM) and H69VP small-cell lung carcinoma cells (IC50 27 nM). Empty liposomes did not affect the IC50 for free DR in the three resistant cell lines, nor did empty liposomes affect the IC50 for other drugs that are part of the multi-drug resistance phenotype (etoposide, vincristine) in lung carcinoma cells. These data indicate the possible value of liposomal DR in overcoming Pgp-mediated drug resistance in human cancer.

Trastuzumab-associated cardiotoxicity

Trastuzumab is a monoclonal antibody used for the treatment of metastatic breast carcinoma in women whose tumors overexpress the HER2 protein. Cardiotoxicity has been reported to occur with trastuzumab when administered alone and in combination with antineoplastic agents, particularly anthracyclines. The risk of cardiotoxicity with trastuzumab has been reported to be 4% with monotherapy and 27% when administered in combination with an anthracycline and cyclophosphamide, but to the author's knowledge severe outcomes, such as death or permanent disability, are uncommon. The majority of reported cardiac effects are mild to moderate, nonspecific, and medically manageable. Signs and symptoms are similar to those observed in patients who develop anthracycline-induced cardiomyopathy and include tachycardia, palpitations, and exertional dyspnea, which may progress to congestive heart failure. The pathogenesis and histologic changes responsible for trastuzumab-associated cardiotoxicity currently are under investigation. Unlike anthracycline-induced toxicity, trastuzumab-associated toxicity usually responds to standard treatment or the discontinuation of trastuzumab, and there is no evidence that the toxicity is dose related. Current methods for the early detection of cardiotoxicity in trastuzumab-treated patients are similar to those used in anthracycline-treated patients. Cardiac function is established at baseline and monitored regularly during treatment by physical examination and measurement of left ventricular ejection fraction. The majority of patients improve with proper treatment, and some are able to continue to receive trastuzumab.

Progress in systemic chemotherapy of primary breast cancer: an overview

Substantial progress has been made in the multidisciplinary management of primary breast cancer during the last 30 years. Adjuvant chemotherapy has been shown to significantly reduce the annual risk of cancer recurrence and mortality, and these effects persist even 15 years after diagnosis. Combination chemotherapy is superior to single-agent therapy and anthracycline-containing regimens. Those that combine an anthracycline with 5-fluorouracil and cyclophosphamide are more effective than regimens without an anthracycline. Six cycles of a single regimen appear to provide optimal benefit. Dose reductions below the standard range are associated with inferior results. Dose increases that require growth factor or hematopoietic stem cell support are under investigation; at this time, the existing results provide no compelling reason to use this strategy outside a clinical trial. Regimens using fixed crossover designs with two non-cross-resistant regimens are being evaluated. The addition of a taxane to anthracycline-containing regimens is currently under intense scrutiny, and preliminary analysis of the first three clinical trials has shown encouraging, albeit not compelling, results. For patients with estrogen receptor-positive breast cancer, the sequential administration of chemotherapy and 5 years of tamoxifen therapy provides additive benefits. No compelling evidence exists to combine ovarian ablation with chemotherapy. Most side effects and toxic effects are self-limited, although premature menopause requires monitoring and preventive interventions to preserve bone mineral density. The small risk of acute leukemia is of concern, and additional research to develop safer regimens is clearly indicated. The overall effect of optimal local/regional treatment combined with an anthracycline-containing adjuvant chemotherapy and a taxane (and, for patients with estrogen receptor-positive tumors, 5 years of tamoxifen therapy) is a greater than 50% reduction in annual risks of recurrence of and death from breast cancer. For most patients at intermediate or high risk of cancer recurrence, the benefits of adjuvant chemotherapy exceed by far its unwanted effects.

A comparison of liposomal formulations of doxorubicin with drug administered in free form: changing toxicity profiles

The anthracycline antibiotic doxorubicin has wide activity against a number of human neoplasms and is used extensively both as a single agent and in combination regimens. In addition to the use of free, unencapsulated doxorubicin, there are two US Food and Drug Administration approved liposomal formulations of doxorubicin currently available, with several additional liposomal formulations being researched either in the laboratory or in clinical trials. The two approved liposomal formulations of doxorubicin have significantly different lipid compositions and loading techniques, which lead to both unique pharmacokinetic and toxicity profiles, distinct from those of the unencapsulated form. This article discusses the toxicities associated with the free form of doxorubicin, as well as those associated with the two most common liposomal formulations, namely Doxil and Myocet. One of the key toxicity issues linked to the use of free doxorubicin is that of both an acute and a chronic form of cardiomyopathy. This is circumvented by the use of liposomal formulations, as these systems tend to sequester the drug away from organs such as the heart, with greater accumulation in liver, spleen and tumours. However, as will be discussed, the liposomal formulations of doxorubicin are not without their own related toxicities, and, in the case of Doxil, may be associated with the unique toxicity of palmar-plantar erythrodysaesthesia. Overall, the use of liposomal doxorubicin allows for a greater lifetime cumulative dose of doxorubicin to be administered, however acute maximal tolerated doses differ significantly, with that of Myocet being essentially equivalent to free doxorubicin, while higher doses of Doxil may be safely administered. This review highlights the differences in both toxicity and pharmacokinetic properties between free doxorubicin and the different liposomal formulations, as have been determined in pre-clinical and clinical testing against a number of different human neoplasms. The need for further testing of the liposomal formulations prior to the replacement of free doxorubicin with liposomal doxorubicin in any established combination therapy regimens, as well as in combination with the newer therapeutics such as monoclonal antibodies is also discussed.

Amphiphilic poly-N-vinylpyrrolidones: synthesis, properties and liposome surface modification

Certain amphiphilic water-soluble polymers including amphiphilic derivatives of polyvinyl pyrrolidone (PVP) were found to be efficient steric protectors for liposomes in vivo. In this study, we have tried to develop synthetic pathways for preparing amphiphilic PVP and to investigate the influence of the hydrophilic/hydrophobic blocks on some properties of resulting polymers and polymer-coated liposomes. To prepare amphiphilic PVP with the end stearyl (S) or palmityl (P) residues, amino- and carboxy-terminated PVP derivatives were first synthesized by the free-radical polymerization of vinyl pyrrolidone in the presence of amino- or carboxy-mercaptans as chain transfer agents, and then modified by interaction of amino-PVP with stearoyl chloride or palmitoyl chloride, or by dicyclohexyl carbodiimide coupling of stearylamine with carboxy-PVP. ESR-spectra of the hydrophobic spin-probe, nitroxyl radical N-oxyl-2-hexyl-2-(10-methoxycarbonyl)decyl-4,4'-dimethyl oxazoline, in the presence of amphiphilic PVP demonstrated good accessibility of terminal P- and S-groups for the interaction with other hydrophobic ligands. Spontaneous micellization and low CMC values (in a low micromolar range) were found for amphiphilic PVP derivatives using the pyrene method. In general, S-PVP forms more stable micelles than P-PVP (at similar MW, CMC values for S-PVP are lower than for P-PVP). It was found that amphiphilic PVP incorporated into negatively charged liposomes effectively prevents polycation(poly-ethylpyridinium-4-vinylchloride)-induced liposome aggregation, completely abolishing it at ca. 10 mol% polymer content in liposomes. Additionally, the liposome-incorporated PVP prevents the fluorescence quenching of the membrane-incorporated hydrophobic fluorescent label [N-(4-fluoresceinthiocarbamoyl)dipalmitoyl-PE] by the free polycation. PVP-modified liposomes were loaded with a self-quenching concentration of carboxyfluorescein, and their destabilization in the presence of mouse serum was investigated following the release of free dye. Amphiphilic PVP with MW between 1,500 and 8,000 provides good steric protection for liposomes. The degree of this protection depends on both polymer concentration and molecular size of the PVP block.

Chemotherapy of metastatic breast cancer: what to expect in 2001 and beyond

Chemotherapy plays an important role in the management of metastatic breast cancer. The anthracyclines (doxorubicin, epirubicin) and the taxanes (paclitaxel, docetaxel) are considered the most active agents for patients with advanced breast cancer. Traditionally, the anthracyclines have been used in combination with cyclophosphamide and 5-fluorouracil (FAC, FEC). The taxanes have single-agent activity similar to older combination chemotherapy treatments. There is great interest in developing anthracycline/taxane combinations. Capecitabine is indicated for patients who progress after anthracycline and taxane therapy. Vinorelbine and gemcitabine have activity in patients with metastatic breast cancer and are commonly used as third- and fourth-line palliative therapy. The role of high-dose chemotherapy is not well-defined and remains experimental. Novel cytotoxic therapy strategies include the development of anthracycline, taxane, and oral fluoropyrimidine analogues; antifolates; topoisomerase I inhibitors, and multidrug resistance inhibitors. A better understanding of the biology of breast cancer is providing novel treatment approaches. Oncogenes and tumor-supressor genes are emerging as important targets for therapy. Trastuzumab, a monoclonal antibody directed against the Her-2/neu protein, has been shown to prolong survival in patients with metastatic breast cancer. Other novel biologic therapies interfere with signal transduction pathways and angiogenesis. The challenge for the next decade will be to integrate these promising agents in the management of metastatic and primary breast cancer.

Encapsulation of c-myc antisense oligodeoxynucleotides in lipid particles improves antitumoral efficacy in vivo in a human melanoma line

Phosphorothioate c-myc antisense oligodeoxynucleotides [S]ODNs (free INX-6295) were encapsulated in a new liposome formulation and the antitumor activity was compared to the unencapsulated antisense in a human melanoma xenograft. The systemic administration of INX-6295 encapsulated in stabilized antisense lipid particles (SALP INX-6295) improved plasma AUC (area under the plasma concentration-time curve) and initial half-life of free INX-6295, resulting in a significant enhancement in tumor accumulation and improvement in tumor distribution of antisense oligodeoxynucleotides. Animals treated with SALP INX-6295 exhibited a prolonged reduction of c-myc expression, reduced tumor growth and increased mice survival. When administered in combination with cisplatin (DDP), SALP INX-6295 produced a complete tumor regression in approximately 30% of treated mice, which persisted for at least 60 days following the first cycle of treatment. Finally, the median survival of mice treated with DDP/SALP INX-6295 increased by 105% compared to 84% for animals treated with the combination DDP/free INX-6295. These data indicate that the biological activity and the therapeutic efficacy of c-myc antisense therapy may be improved when these agents are administered in lipid-based delivery systems.

p-Nitrophenylcarbonyl-PEG-PE-liposomes: fast and simple attachment of specific ligands, including monoclonal antibodies, to distal ends of PEG chains via p-nitrophenylcarbonyl groups

We have attempted to simplify the procedure for coupling various ligands to distal ends of liposome-grafted polyethylene glycol (PEG) chains and to make it applicable for single-step binding of a large variety of a primary amino group-containing substances, including proteins and small molecules. With this in mind, we have introduced a new amphiphilic PEG derivative, p-nitrophenylcarbonyl-PEG-1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (pNP-PEG-DOPE), synthesized by reaction of DOPE with excess of bis(p-nitrophenylcarbonyl)-PEG in a chloroform/triethylamine mixture. pNP-PEG-DOPE readily incorporates into liposomes via its PE residue, and easily binds primary amino group-containing ligands via its water-exposed pNP groups, forming stable and non-toxic urethane (carbamate) bonds. The reaction between the pNP group and the ligand amino group proceeds easily and quantitatively at pH around 8.0, and remaining free pNP groups are promptly eliminated by spontaneous hydrolysis. Therefore, pNP-PEG-DOPE could serve as a very convenient tool for protein attachment to the distal ends of liposome-grafted PEG chains. To investigate the applicability of the suggested protocol for the preparation of long-circulating targeted liposomes, we have coupled several proteins, such as concanavalin A (ConA), wheat germ agglutinin (WGA), avidin, monoclonal antimyosin antibody 2G4 (mon2G4), and monoclonal antinucleosome antibody 2C5 (mon2C5) to PEG-liposomes via terminal pNP groups and studied whether the specific activity of these immobilized proteins is preserved. The method permits the binding of several dozens protein molecules per single 200 nm liposome. All bound proteins completely preserve their specific activity. Lectin-liposomes are agglutinated by the appropriate polyvalent substrates (mannan for ConA-liposomes and glycophorin for WGA-liposomes); avidin-liposomes specifically bind with biotin-agarose; antibody-liposomes demonstrate high specific binding to the substrate monolayer both in the direct binding assay and in ELISA. A comparison of the suggested method with the method of direct membrane incorporation was made. The effect of the concentration of liposome-grafted PEG on the preservation of specific protein activity in different coupling protocols was also investigated. It was also shown that pNP-PEG-DOPE-liposomes with and without attached ligands demonstrate increased stability in mouse serum.

Liposomal encapsulated anthracyclines: new therapeutic horizons

After two decades of work in liposomal formulations for clinical use, two preparations containing doxorubicin (Doxil, ALZA, Pablo Alto, CA; and Evacet, The Liposome Company, Princeton, NJ), and one containing daunorubicin (DaunoXome; Gilead Sciences, Foster City, CA) have been undergoing widespread clinical study. Results have lived up to the promise that liposomal encapsulation may lead to toxicity attenuation, while retaining or even enhancing the efficacy of the parent anthracyclines. The eventual role of these agents in clinical practice is being defined in a number of studies that are reviewed herein. Already, approved indications have been achieved for doxorubicin against Kaposi's sarcoma and ovarian cancers, and for daunorubicin against Kaposi's sarcoma. The three compounds vary widely in their pharmacology, and these differences may contribute to their preferential localization into certain tumors. Additional indications for these liposomal encapsulated anthracyclines are likely to be established in the ensuing years.

Reduced cardiotoxicity and preserved antitumor efficacy of liposome-encapsulated doxorubicin and cyclophosphamide compared with conventional doxorubicin and cyclophosphamide in a randomized, multicenter trial of metastatic breast cancer

PURPOSE

To determine whether Myocet (liposome-encapsulated doxorubicin; The Liposome Company, Elan Corporation, Princeton, NJ) in combination with cyclophosphamide significantly reduces doxorubicin cardiotoxicity while providing comparable antitumor efficacy in first-line treatment of metastatic breast cancer (MBC).

PATIENTS AND METHODS

Two hundred ninety-seven patients with MBC and no prior chemotherapy for metastatic disease were randomized to receive either 60 mg/m(2) of Myocet (M) or conventional doxorubicin (A), in combination with 600 mg/m(2) of cyclophosphamide (C), every 3 weeks until disease progression or unacceptable toxicity. Cardiotoxicity was defined by reductions in left-ventricular ejection fraction, assessed by serial multigated radionuclide angiography scans, or congestive heart failure (CHF). Antitumor efficacy was assessed by objective tumor response rates (World Health Organization criteria), time to progression, and survival.

RESULTS

Six percent of MC patients versus 21% (including five cases of CHF) of AC patients developed cardiotoxicity (P =.0002). Median cumulative doxorubicin dose at onset was more than 2,220 mg/m(2) for MC versus 480 mg/m(2) for AC (P =.0001, hazard ratio, 5.04). MC patients also experienced less grade 4 neutropenia. Antitumor efficacy of MC versus AC was comparable: objective response rates, 43% versus 43%; median time to progression, 5.1% versus 5.5 months; median time to treatment failure, 4.6 versus 4.4 months; and median survival, 19 versus 16 months.

CONCLUSION

Myocet improves the therapeutic index of doxorubicin by significantly reducing cardiotoxicity and grade 4 neutropenia and provides comparable antitumor efficacy, when used in combination with cyclophosphamide as first-line therapy for MBC.