Reduced cardiotoxicity and comparable efficacy in a phase IIItrial of pegylated liposomal doxorubicin HCl(CAELYX™/Doxil®) versus conventional doxorubicin forfirst-line treatment of metastatic breast cancer

Optimizing the treatment of metastatic breast cancer

There is currently no standard care for metastatic breast cancer; consequently, individual patient and tumor characteristics are among several factors considered in treatment decisions. Clinical studies continue to clarify the roles of endocrine therapy, chemotherapy, and biologic therapy, and results have been promising. For patients with hormone receptor-positive disease, several endocrine agents are currently available including selective estrogen receptor (ER) modulators (tamoxifen and toremifene), aromatase inhibitors (anastrozole, exemestane, and letrozole), as well as the selective ER down-regulator, fulvestrant. Effective first- and second-line, single-agent chemotherapeutic treatments include the taxanes, anthracyclines, vinorelbine, capecitabine, and gemcitabine. The benefits of sequential, single-agent versus combination chemotherapy are also being evaluated. Although combination chemotherapy generally results in a greater objective response, it is associated with similar survival and usually greater toxicity compared with sequential, single-agent chemotherapy. Research involving biologic therapy continues to provide encouraging results for patients with metastatic breast cancer. Chemotherapy plus trastuzumab has been shown to result in greater overall survival versus chemotherapy alone in human epidermal growth factor 2 (HER-2)-positive patients. Trastuzumab has been associated with cardiotoxicity when administered with conventional anthracyclines. Newer formulations of anthracyclines have been developed (e.g., liposomal anthracyclines) to decrease the incidence of cardiotoxicity, and these provide additional treatment options for patients with metastatic breast cancer. The potential effect of all of these endocrine, chemotherapeutic, and biologic treatments on quality of life is an important consideration. Additionally, integrating patient concerns into treatment decisions and collaborating with cross-disciplinary healthcare providers can help to manage the disease more effectively.

Role of pegylated liposomal doxorubicin in ovarian cancer

OBJECTIVES

Safe, effective treatments are needed for relapsed ovarian cancer. Goals include improving symptoms, enhancing quality of life, and prolonging survival. The plethora of agents currently available present difficult choices for physicians. The present effort seeks to examine the role of one of these agents, pegylated liposomal doxorubicin.

METHODS

A roundtable meeting of experts in the management of ovarian carcinoma was held to build consensus around the present and future role of pegylated liposomal doxorubicin for ovarian cancer and other gynecologic malignancies.

RESULTS

Pegylated liposomal doxorubicin is effective and well tolerated in relapsed ovarian cancer. When compared with topotecan in a phase III randomized trial, pegylated liposomal doxorubicin showed several advantages: improved quality of life, fewer severe adverse events, fewer dose modifications, less hematologic support, and lower total cost per patient. In platinum-sensitive patients, pegylated liposomal doxorubicin also produced a survival advantage. Results from prospective and retrospective studies further demonstrate the improved cardiac safety of pegylated liposomal doxorubicin compared to conventional anthracyclines.

CONCLUSIONS

Based on survival and toxicity advantages and a once-monthly administration schedule, pegylated liposomal doxorubicin is the first-choice nonplatinum agent for relapsed ovarian cancer. Pegylated liposomal doxorubicin may also have clinical application in combination regimens for platinum-sensitive ovarian cancer, as consolidation/maintenance therapy for ovarian cancer, as a component of first-line therapy for ovarian cancer, and in the treatment of other gynecologic malignancies. Future clinical trials will further define and maximize the role of pegylated liposomal doxorubicin in the treatment of ovarian cancer and other gynecologic malignancies.

Efficacy and safety of liposomal anthracyclines in Phase I/II clinical trials

Preclinical studies have established the pharmacologic advantages of liposomal anthracyclines, including pharmacokinetic profiles after bolus dosing that resemble continuous infusion of conventional anthracyclines, increased drug concentrations in tumor cells compared with the surrounding tissues, and reduced toxicity relative to conventional anthracycline treatment. Based on these studies, many phase I and phase II clinical trials were conducted to assess the safety and potential activity of liposomal anthracyclines in the management of both solid and hematologic tumors. These studies provided valuable insight into the safety of pegylated liposomal doxorubicin (Doxil/Caelyx [PLD]), nonpegylated liposomal doxorubicin (Myocet [NPLD]), and liposomal daunorubicin (DaunoXome [DNX]) over a range of doses, either as single-agent therapy or in combination with other cytotoxic agents. Other liposomal anthracyclines in development may be well tolerated but their activity remains to be elucidated by clinical trials. The available data also suggest that liposomal anthracyclines have activity not only against tumor types with known sensitivity to conventional anthracyclines, but also potentially for tumors that are typically anthracycline-resistant. Despite the availability of clinical data from a wide variety of tumor types and patient populations, further studies of liposomal anthracycline therapy are needed to fully establish their safety, efficacy, and dosing in the treatment of these patients.

Liposomal anthracycline administration and toxicity management: A nursing perspective

Nursing care of the patient receiving chemotherapy includes patient education and drug administration, as well as ongoing assessment, early identification, and intervention for side effects. Two liposomal anthracyclines are available in the United States, pegylated liposomal doxorubicin (Doxil/Caelyx [PLD]) and liposomal daunorubicin (DaunoXome [DNX]). Because of their unique liposomal formulations, the administration and toxicity profiles of these agents are different from those of conventional anthracyclines, as well as each other. Common severe toxicities of conventional anthracycline treatment such as nausea/vomiting, alopecia, and neutropenia are less frequent and less severe during liposomal anthracycline treatment, and cumulative-dose cardiotoxicity is rare, particularly with PLD therapy. Dose-related adverse events with liposomal anthracycline therapy include stomatitis and neutropenia, and more frequent doses of PLD are associated with hand-foot syndrome. Ongoing nursing assessment, patient education, and adjustments to the dose or dose-schedule can reduce the severity or frequency of these toxicities. Nurses must be aware of the unique characteristics of liposomal anthracycline therapy to provide optimal patient education and nursing care.

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 anthracycline treatment for ovarian cancer

Platinum/taxane regimens induce high response rates and prolong survival in women with ovarian cancer. After recurrence, however, response to second-line chemotherapy is limited. Pegylated liposomal doxorubicin (Doxil/Caelyx [PLD]), is the only liposomal anthracycline indicated for second-line treatment of platinum- and paclitaxel-refractory ovarian cancer. Response rates ranged from 14% to 20% in nonrandomized trials of this patient population. In a large phase 3 randomized trial, single-agent PLD and topotecan had similar efficacy overall in response rates, but PLD-treated patients had significantly improved overall survival compared with topotecan with a pronounced advantage in platinum-sensitive patients. Another randomized trial reported that PLD and paclitaxel were comparable with regards to response rate, progression-free survival, and overall survival, regardless of the degree of platinum sensitivity. Additional nonrandomized trials of PLD in combination with other active agents resulted in response rates ranging from 20% to 76%. PLD is generally well tolerated and its side-effect profile compares favorably with other commonly used chemotherapeutic agents in this clinical setting. Proper dosing and monitoring may further enhance tolerability while preserving the efficacy of this versatile agent for ovarian cancer.

Cardiac Safety of Pegylated Liposomal Doxorubicin (Doxil®/Caelyx®) Demonstrated by Endomyocardial Biopsy in Patients with Advanced Malignancies

Although conventional doxorubicin demonstrates broad activity, its clinical use is limited by cardiotoxicity. A more recent analysis suggests conventional doxorubicin-related cardiotoxicity occurs more frequently and at lower cumulative doses than previously reported. Pegylated liposomal doxorubicin, designed to maintain or improve conventional doxorubicin activity while reducing toxicities, has demonstrated improved cardiac safety versus conventional doxorubicin. In this prospective study, we evaluated endomyocardial biopsies to determine the cardiac effects of pegylated liposomal doxorubicin in patients with advanced malignancies receiving doxorubicin-equivalent doses > or = 550 mg/m2 (including pegylated liposomal doxorubicin) or > or = 400 mg/m2 pegylated liposomal doxorubicin alone. Eight patients were enrolled, and 10 biopsy scores were obtained (two patients had two biopsies). Median biopsy score (Billingham scale) was 0.75 (range, 0-1.5) after a median pegylated liposomal doxorubicin dose of 707.5 mg/m2 and median total anthracycline exposure of 908.5 mg/m2. These results suggest that pegylated liposomal doxorubicin minimizes doxorubicin-related cardiotoxicity, even at doses exceeding the recommended lifetime cumulative conventional dose (450-550 mg/m2).

New treatment strategies for multiple myeloma

Multiple myeloma remains an incurable disease despite aggressive, high-dose therapy and intensive supportive care. Newer therapies with good safety profiles are needed for patients with multiple myeloma to improve the quality of responses and prolong survival. Novel treatment strategies for multiple myeloma include replacing conventional doxorubicin with pegylated liposomal doxorubicin and reducing the dexamethasone dose (DVd) in the widely accepted VAD (vincristine, conventional doxorubicin, dexamethasone) regimen to improve the safety profile. Because of its antiangiogenic and immunomodulatory effects, thalidomide has also been explored for use in the treatment of multiple myeloma and has demonstrated increased response rates when used in combination with dexamethasone. These findings subsequently led to the evaluation of the role of thalidomide in combination with pegylated liposomal doxorubicin, vincristine, and reduced-dose dexamethasone (the DVd-T regimen). This regimen was associated with response rates greater than 80% in patients with both newly diagnosed and relapsed/refractory multiple myeloma. Future applications of this and similar regimens for the treatment of multiple myeloma are currently being explored.

Pharmacokinetics of pegylated liposomal Doxorubicin: review of animal and human studies

Pegylated liposomal doxorubicin (doxorubicin HCl liposome injection; Doxil or Caelyx) is a liposomal formulation of doxorubicin, reducing uptake by the reticulo-endothelial system due to the attachment of polyethylene glycol polymers to a lipid anchor and stably retaining drug as a result of liposomal entrapment via an ammonium sulfate chemical gradient. These features result in a pharmacokinetic profile characterised by an extended circulation time and a reduced volume of distribution, thereby promoting tumour uptake. Preclinical studies demonstrated one- or two-phase plasma concentration-time profiles. Most of the drug is cleared with an elimination half-life of 20-30 hours. The volume of distribution is close to the blood volume, and the area under the concentration-time curve (AUC) is increased at least 60-fold compared with free doxorubicin. Studies of tissue distribution indicated preferential accumulation into various implanted tumours and human tumour xenografts, with an enhancement of drug concentrations in the tumour when compared with free drug. Clinical studies of pegylated liposomal doxorubicin in humans have included patients with AIDS-related Kaposi's sarcoma (ARKS) and with a variety of solid tumours, including ovarian, breast and prostate carcinomas. The pharmacokinetic profile in humans at doses between 10 and 80 mg/m(2) is similar to that in animals, with one or two distribution phases: an initial phase with a half-life of 1-3 hours and a second phase with a half-life of 30-90 hours. The AUC after a dose of 50 mg/m(2) is approximately 300-fold greater than that with free drug. Clearance and volume of distribution are drastically reduced (at least 250-fold and 60-fold, respectively). Preliminary observations indicate that utilising the distinct pharmacokinetic parameters of pegylated liposomal doxorubicin in dose scheduling is an attractive possibility. In agreement with the preclinical findings, the ability of pegylated liposomes to extravasate through the leaky vasculature of tumours, as well as their extended circulation time, results in enhanced delivery of liposomal drug and/or radiotracers to the tumour site in cancer patients. There is evidence of selective tumour uptake in malignant effusions, ARKS skin lesions and a variety of solid tumours. The toxicity profile of pegylated liposomal doxorubicin is characterised by dose-limiting mucosal and cutaneous toxicities, mild myelosuppression, decreased cardiotoxicity compared with free doxorubicin and minimal alopecia. The mucocutaneous toxicities are dose-limiting per injection; however, the reduced cardiotoxicity allows a larger cumulative dose than that acceptable for free doxorubicin. Thus, pegylated liposomal doxorubicin represents a new class of chemotherapy delivery system that may significantly improve the therapeutic index of doxorubicin.