Doxil®--the first FDA-approved nano-drug: lessons learned.

The results obtained in this study establish that liposome formulations incorporating a synthetic polyethylene glycol-derivatized phospholipid have a pronounced effect on liposome tissue distribution and can produce a large increase in the pharmacological efficacy of encapsulated antitumor drugs. This effect is substantially greater than that observed previously with conventional liposomes and is associated with a more than 5-fold prolongation of liposome circulation time in blood, a marked decrease in uptake by tissues such as liver and spleen, and a corresponding increased accumulation in implanted tumors. These and other properties described here have expanded considerably the prospects of liposomes as an effective carrier system for a variety of pharmacologically active macromolecules.

https://www.pnas.org/content/pnas/88/24/11460.full.pdf

Sterically stabilized liposomes: improvements in pharmacokinetics and antitumor therapeutic efficacy.

https://www.cell.com/trends/biotechnology/pdf/S0167-7799(00)89017-4.pdf

Engineering liposomes for drug delivery: progress and problems

Folate-mediated tumor cell targeting of liposome-entrapped doxorubicin in vitro

Liposomal compositions encapsulating bioactive agents and having improved circulation longevity of the agents are disclosed Such liposomes combine a low pH of the solution in which a bioactive agent is entrapped and a sugar-modified lipid or an amine-bearing lipid, the combination of which enhances the retention of the encapsulated bioactive agent and thereby promotes circulation longevity The present invention also discloses methods of making and using such compositions

Liposomal compositions for enhanced retention of bioactive agents

The pharmacological and therapeutic effects of Adriamycin entrapped in positively charged and negatively charged liposomes were compared with those of free Adriamycin in mice. Liposomes were composed of phosphatidylcholine and cholesterol mixed with stearyl amine (positive charge) or phosphatidylserine (negative charge). Positive liposomes with entrapped Adriamycin effectively retarded the in vivo uptake of drug in cardiac tissue when compared to free drug or drug entrapped in negative liposomes. At 4 mg/kg i.v., the peak drug concentration in heart occurred in 30 min following administration of free Adriamycin or Adriamycin entrapped in negative liposomes, compared to 5 min with Adriamycin entrapped in positive liposomes. The maximum drug concentration achieved with positive liposomes in cardiac tissue was approximately one-half that of free drug or drug entrapped in negative liposomes. In addition, the cardiac concentration × time values for Adriamycin administered in positive liposomes were considerably less than that of free drug or negative liposomes for the 24-hr period of observation. The liposomal Adriamycin was preferentially concentrated in liver, spleen, and lungs. Electron microscopic studies demonstrated that the myocytes and myofibrillar structure of cardiac muscle were markedly well preserved with Adriamycin in positive liposomes, in contrast to the two other delivery forms. The antitumor activity of the drug against murine ascitic P388 leukemia and Lewis lung carcinoma demonstrated an identical effect when administered as free drug or entrapped in positive liposomes. The specific positively charged liposome developed in these studies selectively reduces the acute cardiotoxicity of Adriamycin without loss of antitumor activity.

https://cancerres.aacrjournals.org/content/canres/40/5/1532.full.pdf

Liposomal Protection of Adriamycin-induced Cardiotoxicity in Mice

Doxorubicin possesses high affinity for binding to cardiolipin. We have utilized these properties in preparing stable liposomes of doxorubicin and cardiolipin with a net positive charge. Doxorubicin liposomes were formed by using 11.2 mumol of drug, 5.6 mumol of cardiolipin, 28.5 mumol of phosphatidylcholine, 19.5 mumol of cholesterol, and 11.1 mumol of stearylamine. These liposomes were sonicated for 90 min at 37 degrees followed by extensive dialysis against buffer. The pharmacological, toxicological, and therapeutic effects of doxorubicin entrapped in cardiolipin liposomes were compared with those of free doxorubicin in mice. At a dose of 4 mg/kg i.v., the peak cardiac concentration was achieved in 30 min following free doxorubicin administration, the value being 8.1 micrograms/g. The peak cardiac concentration with doxorubicin in cardiolipin liposomes was obtained at 5 min with a value of 2.8 micrograms/g of tissue. The cardiac concentration X time values for free doxorubicin for the 24-hr period of observation were 55.1 micrograms X hr/g, whereas it was only 7.8 micrograms X hr/g with the drug entrapped in cardiolipin liposomes. Compared to free drug, the liposomal entrapped doxorubicin significantly reduced the histopathological lesions in cardiac tissue of mice at a dose of 15 mg/kg as determined by electron microscopy. The nadir of peripheral white blood cell counts in mice with free drug, 6 mg/kg, was observed on Day 3 which was 50% of control, whereas with liposomal encapsulated drug it was reduced only 23% on Day 7. Doxorubicin in cardiolipin liposomes demonstrated enhanced chemotherapeutic potential against murine ascitic P388 leukemia with a 144% increased life span compared to 55% increased life span with free drug at a dose of 7.5 mg/kg on Days 1, 3, and 7. We conclude that doxorubicin liposomes developed in these studies possess improved therapeutic action as demonstrated by their ability to reduce the toxicity of the drug substantially.

https://cancerres.aacrjournals.org/content/canres/45/2/796.full.pdf

Pharmacological, toxicological, and therapeutic evaluation in mice of doxorubicin entrapped in cardiolipin liposomes.

The chronic cardiotoxicity of doxorubicin as a free drug or entrapped in positive and negative liposomes was morphologically evaluated in mice treated seven times i.v. at a dose of 4 mg/kg. Liposomes were composed of phosphatidylcholine, cholesterol, and stearylamine (positive charge) or phosphatidylserine (negative charge). Administration of free doxorubicin caused a pattern of cardiac damage characterized by loss of myofiber elements, mitochondrial damage, nuclear abnormalities, swollen and distended sarcoplasmic reticulum leading to vacuolization, and increasing myeloid body accumulation. Cardiac tissues of mice treated with doxorubicin entrapped in negatively charged liposomes demonstrated pronounced loss of filaments, enlarged mitochondria, disruptive loss of crests, and expanded nuclear membrane. However, electron microscopic examination of the cardiac muscles of mice treated with positive liposomes demonstrated a significant protection from drug-induced toxicity, with only minor loss of parallel fibrillar arrangement and myofilaments in limited focal areas. The majority of the tissue demonstrated normal vasculature and intercalation of myocytes as compared to control groups. The mean qualitative and quantitative scores of toxic lesions for free doxorubicin and entrapped in negative liposomes are 2.7 and 2.23, respectively. However, the mean score for the group of mice treated with positive liposomes is only 1.12, showing a better than 2-fold scoring protection of both the extent and severity of cardiac lesions.

/pdf/doxorubicin-induced-chronic-cardiotoxicity-and-its-568a3cjrjc.pdf

Doxorubicin-induced chronic cardiotoxicity and its protection by liposomal administration.

Acute lymphoblastic leukemia--hand mirror variant--was extensively restudied in a 22-year-old white female who survived for 22 months without therapy. Immune complexes to the baboon endogenous virus (BaEV) were found in the bone marrow plasma of the relapse specimen in 1977, but not in the bone marrow plasma from the terminal state in 1979. Immunoperoxidase-tagged IgM antibody prepared from the patient's bone marrow plasma revealed BaEV antigen on the tip of the uropod of the HMC at the time immune complexes were found in the marrow. Absence of immune complexes in the marrow. Absence of immune complexes in the bone marrow in the terminal state suggested a failure of the patient's immune surveillance system and/or possible immune suppression by chemotherapy.

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Papers

Liposomal Protection of Adriamycin-induced Cardiotoxicity in Mice

Pharmacological, toxicological, and therapeutic evaluation in mice of doxorubicin entrapped in cardiolipin liposomes.

Doxorubicin-induced chronic cardiotoxicity and its protection by liposomal administration.

Acute lymphoblastic leukemia--hand mirror variant--viral immune interrelationship as demonstrated by ultrastructural studies.