Preclinical toxicological study of long-circulating and fusogenic liposomes co-encapsulating paclitaxel and doxorubicin in synergic ratio.

Combination therapy between paclitaxel (PTX) and doxorubicin (DXR) is applied as the first-line treatment of breast cancer. Co-administration of drugs at synergistic ratio for treatment is facilitated with the use of nanocarriers, such as liposomes. However, despite the high response rate of solid tumors to this combination, a synergism of cardiotoxicity may limit the use. Thus, the objective of this work was to investigate the toxicity of long-circulating and fusogenic liposomes co-encapsulating PTX and DXR at the synergistic molar ratio (1:10) (LCFL-PTX/DXR). For this, clinical chemistry, histopathological analysis and electrocardiographic exams were performed on female Balb/c mice that received a single intravenous dose of LCFL-PTX/DXR. The results of the study indicated that the LD50 dose range (lethal dose for 50% of animals) of the LCFL-PTX/DXR treatment (28.9-34.7 mg/kg) is much higher than that found for free PTX/DXR treatment (20.8-23.1 mg/kg). In addition, liposomes promoted cardiac protection by not raising CK-MB levels in animals, keeping cardiomyocytes without injury or electrocardiographic changes. After 14 days of treatment, free PTX/DXR caused prolongation of the QRS interval when compared to LCFL-PTX/DXR treatment at the same dose (37.0 ± 5.01 ms and 30.83 ± 2.62 ms, respectively, with p = 0.017). The survival rate of animals treated with LCFL-PTX/DXR was three times higher than that of those treated with free drugs. Thus, it was established that the toxicity of LCFL-PTX/DXR is reduced compared to the combination of free PTX/DXR and this platform has advantages for the clinical treatment of breast cancer.

Liposomal paclitaxel induces apoptosis, cell death, inhibition of migration capacity and antitumoral activity in ovarian cancer.

The main goal of this study is to evaluate the efficacy of the paclitaxel (PTX) drug formulated with a liposomal nanosystem (L-PTX) in a peritoneal carcinomatosis derived from ovarian cancer. In vitro cell viability studies with the human ovarian cancer line A2780 showed a 50% decrease in the inhibitory concentration for L-PTX compared to free PTX. A2780 cells treated with the L-PTX formulation demonstrated a reduced capacity to form colonies in comparison to those treated with PTX. Cell death following L-PTX administration hinted at apoptosis, with most cells undergoing initial apoptosis. A2780 cells exhibited an inhibitory migration profile when analyzed by Wound Healing and real-time cell analysis (xCELLigence) methods after L-PTX administration. This inhibition was related to decreased expression of the zinc finger E-box-binding homeobox 1 (ZEB1) and transforming growth factor 2 (TGF-ß2) genes. In vivoL-PTX administration strongly inhibited tumor cell proliferation in ovarian peritoneal carcinomatosis derived from ovarian cancer, indicating higher antitumor activity than PTX. L-PTX formulation did not show toxicity in the mice model. This study demonstrated that liposomal paclitaxel formulations are less toxic to normal tissues than free paclitaxel and are more effective in inhibiting tumor cell proliferation/migration and inducing ZEB1/TGF-ß2 gene expression.

Triggered Drug Release From Liposomes: Exploiting the Outer and Inner Tumor Environment.

Since more than 40 years liposomes have being extensively studied for their potential as carriers of anticancer drugs. The basic principle behind their use for cancer treatment consists on the idea that they can take advantage of the leaky vasculature and poor lymphatic drainage present at the tumor tissue, passively accumulating in this region. Aiming to further improve their efficacy, different strategies have been employed such as PEGlation, which enables longer circulation times, or the attachment of ligands to liposomal surface for active targeting of cancer cells. A great challenge for drug delivery to cancer treatment now, is the possibility to trigger release from nanosystems at the tumor site, providing efficacious levels of drug in the tumor. Different strategies have been proposed to exploit the outer and inner tumor environment for triggering drug release from liposomes and are the focus of this review.

Combined paclitaxel-doxorubicin liposomal results in positive prognosis with infiltrating lymphocytes in lung metastasis.

Aim: To investigate the effect of liposomes containing the classical cytotoxic drugs paclitaxel and doxorubicin (Lipo-Pacli/Dox), against a metastatic breast cancer model. We also investigated if Lipo-Pacli/Dox was capable of reverting the tolerogenic environment of metastatic lesions. Materials & methods: Immunogenic cell death induction by the Pacli/Dox combination was assessed in vitro. Antitumor activity and in vivo safety of Lipo-Pacli/Dox were evaluated using a 4T1 breast cancer mouse model Results: Lipo-Pacli/Dox, with a size of 189 nm and zeta potential of -5.01 mV, promoted immune system activation and partially controlled the progression of pulmonary metastasis. Conclusion: Lipo-Pacli/Dox was useful to control both primary tumor and lung metastasis in breast cancer (4T1) mice model. Additionally, Lipo-Pacli/Dox acts as an immunological modulator for this metastatic breast cancer model.

Development of Long-Circulating and Fusogenic Liposomes Co-encapsulating Paclitaxel and Doxorubicin in Synergistic Ratio for the Treatment of Breast Cancer.

BACKGROUND: The co-encapsulation of paclitaxel (PTX) and doxorubicin (DXR) in liposomes has the potential to offer pharmacokinetic and pharmacodynamic advantages, providing delivery of both drugs to the tumor at the ratio required for synergism. OBJECTIVE: To prepare and characterize long-circulating and fusogenic liposomes co-encapsulating PTX and DXR in the 1:10 molar ratio (LCFL-PTX/DXR). METHODS: LCFL-PTX/DXR was prepared by the lipid film formation method. The release of PTX and DXR from liposomes was performed using a dialysis method. Studies of cytotoxicity, synergism, and cellular uptake were also carried out. RESULTS: The encapsulation percentage of PTX and DXR was 74.1 ± 1.8 % and 89.6 ± 12.3%, respectively, and the mean diameter of the liposomes was 244.4 ± 28.1 nm. The vesicles remained stable for 30 days after their preparation. The drugs were simultaneously released from vesicles during 36 hours, maintaining the drugs combination in the previously established ratio. Cytotoxicity studies using 4T1 breast cancer cells showed lower inhibitory concentration 50% (IC50) value for LCFL-PTX/DXR treatment (0.27 ± 0.11 µm) compared to the values of free drugs treatment. In addition, the combination index (CI) assessed for treatment with LCFL-PTX/DXR was equal to 0.11 ± 0.04, showing strong synergism between the drugs. Cell uptake studies have confirmed that the molar ratio between PTX and DXR is maintained when the drugs are administered in liposomes. CONCLUSION: It was possible to obtain LCFL-PTX/DXR suitable for intravenous administration, capable of releasing the drugs in a fixed synergistic molar ratio in the tumor region.

Short and Long-Term Effects of the Exposure of Breast Cancer Cell Lines to Different Ratios of Free or Co-Encapsulated Liposomal Paclitaxel and Doxorubicin.

BACKGROUND: Associating paclitaxel (PTX) to doxorubicin (DXR) is one of the main chemotherapy strategies for breast cancer (BC) management. Protocols currently available consist in administering both drugs on their maximum tolerated dose, not taking into account the possible differences in efficacy due to their combination ratio. In the present study, the short and long-term cytotoxic effects as well as migratory effects of PTX, DXR, and its combinations at 10:1; 1:1 and 1:10 PTX:DXR molar ratios either free or co-encapsulated in liposomes were evaluated against three human BC cell lines (MDA-MB-231, MCF-7, and SKBR-3). METHOD: The MTT assay was used to screen for synergy or antagonism between PTX and DXR and the combination index value was calculated using the CalcuSyn software. Nuclear morphological alterations were evaluated by staining the cells with Hoescht 33342. The investigation of senescence and clonogenicity of BC cell lines exposed to different treatments was also studied. In addition, the ability of these cells to migrate was assessed. RESULTS: Taken together, the results presented herein allow us to suggest that there is no benefit in enhancing the PTX concentration above that of DXR in the combination for any of the three cell lines tested. CONCLUSION: The developed liposomes co-encapsulating PTX and DXR in different molar ratios retained the biological properties of the mixture of free drugs and are valuable for planning new therapeutic strategies.

Investigation of the antitumor activity and toxicity of long-circulating and fusogenic liposomes co-encapsulating paclitaxel and doxorubicin in a murine breast cancer animal model.

To associate paclitaxel (PTX) with doxorubicin (DXR) is one of the main chemotherapy strategies for breast cancer (BC) management. Despite the high response rates for this combination, it presents a cardiotoxic synergism, attributed to pharmacokinetic interactions between PTX and both DXR and its metabolite, doxorubicinol. One of the main strategies to minimize the cardiotoxicity of the combination is to extend the interval of time between DXR and PTX administration. However, it has been previously suggested that their co-administration leads to better efficacy compared to their sequential administration. In the present study, we investigated different molar ratio combinations of PTX:DXR (10:1; 1:1, and 1:10) against the 4T1 murine breast cancer cell line and concluded that there is no benefit of enhancing PTX concentration above that of DXR on the combination. Therefore, we obtained a long-circulating and fusogenic liposomal formulation co-encapsulating PTX and DXR (LCFL-PTX/DXR) at a molar ratio of 1:10, respectively, which maintained the in vitro biological activity of the combination. This formulation was investigated for its antitumor activity and toxicity in Balb/c mice bearing 4T1 breast tumor, and compared to treatments with free PTX, free DXR, and the mixture of free PTX:DXR at 1:10 molar ratio. The higher tumor inhibition ratios were observed for the treatments with free and co-encapsulated PTX:DXR in liposomes (66.87 and 66.52%, respectively, P>0.05) as compared to the control. The great advantage of the treatment with LCFL-PTX/DXR was its improved cardiac toxicity profile. While degeneration was observed in the hearts of all animals treated with the free PTX:DXR combination, no signs of cardiac toxicity were observed for animals treated with the LCFL-PTX/DXR. Thus, LCFL-PTX/DXR enables the co-administration of PTX and DXR, and might be considered valuable for breast cancer management.