In vitro thermo-chemosensitivity screening of spontaneous human tumors: significant potentiation for cisplatin but not adriamycin

The Rationale for "Laser-Induced Thermal Therapy (LITT) and Intratumoral Cisplatin" Approach for Cancer Treatment

Cisplatin is one of the most widely used anticancer drugs in the treatment of various types of solid human cancers, as well as germ cell tumors, sarcomas, and lymphomas. Strong evidence from research has demonstrated higher efficacy of a combination of cisplatin and derivatives, together with hyperthermia and light, in overcoming drug resistance and improving tumoricidal efficacy. It is well known that the antioncogenic potential of CDDP is markedly enhanced by hyperthermia compared to drug treatment alone. However, more recently, accelerators of high energy particles, such as synchrotrons, have been used to produce powerful and monochromatizable radiation to induce an Auger electron cascade in cis-platinum molecules. This is the concept that makes photoactivation of cis-platinum theoretically possible. Both heat and light increase cisplatin anticancer activity via multiple mechanisms, generating DNA lesions by interacting with purine bases in DNA followed by activation of several signal transduction pathways which finally lead to apoptosis. For the past twenty-seven years, our group has developed infrared photo-thermal activation of cisplatin for cancer treatment from bench to bedside. The future development of photoactivatable prodrugs of platinum-based agents injected intratumorally will increase selectivity, lower toxicity and increase efficacy of this important class of antitumor drugs, particularly when treating tumors accessible to laser-based fiber-optic devices, as in head and neck cancer. In this article, the mechanistic rationale of combined intratumor injections of cisplatin and laser-induced thermal therapy (CDDP-LITT) and the clinical application of such minimally invasive treatment for cancer are reviewed.

Drug development of lyso-thermosensitive liposomal doxorubicin: Combining hyperthermia and thermosensitive drug delivery

We review the drug development of lyso-thermosensitive liposomal doxorubicin (LTLD) which is the first heat-activated formulation of a liposomal drug carrier to be utilized in human clinical trials. This class of compounds is designed to carry a payload of a cytotoxic agent and adequately circulate in order to accumulate at a tumor that is being heated. At the target the carrier is activated by heat and releases its contents at high concentrations. We summarize the preclinical and clinical experience of LTLD including its successes and challenges in the development process.

Investigation of Particle Accumulation, Chemosensitivity and Thermosensitivity for Effective Solid Tumor Therapy Using Thermosensitive Liposomes and Hyperthermia

Doxorubicin (Dox) loaded thermosensitive liposomes (TSLs) have shown promising results for hyperthermia-induced local drug delivery to solid tumors. Typically, the tumor is heated to hyperthermic temperatures (41-42 °C), which induced intravascular drug release from TSLs within the tumor tissue leading to high local drug concentrations (1-step delivery protocol). Next to providing a trigger for drug release, hyperthermia (HT) has been shown to be cytotoxic to tumor tissue, to enhance chemosensitivity and to increase particle extravasation from the vasculature into the tumor interstitial space. The latter can be exploited for a 2-step delivery protocol, where HT is applied prior to i.v. TSL injection to enhance tumor uptake, and after 4 hours waiting time for a second time to induce drug release. In this study, we compare the 1- and 2-step delivery protocols and investigate which factors are of importance for a therapeutic response. In murine B16 melanoma and BFS-1 sarcoma cell lines, HT induced an enhanced Dox uptake in 2D and 3D models, resulting in enhanced chemosensitivity. In vivo, therapeutic efficacy studies were performed for both tumor models, showing a therapeutic response for only the 1-step delivery protocol. SPECT/CT imaging allowed quantification of the liposomal accumulation in both tumor models at physiological temperatures and after a HT treatment. A simple two compartment model was used to derive respective rates for liposomal uptake, washout and retention, showing that the B16 model has a twofold higher liposomal uptake compared to the BFS-1 tumor. HT increases uptake and retention of liposomes in both tumors models by the same factor of 1.66 maintaining the absolute differences between the two models. Histology showed that HT induced apoptosis, blood vessel integrity and interstitial structures are important factors for TSL accumulation in the investigated tumor types. However, modeling data indicated that the intraliposomal Dox fraction did not reach therapeutic relevant concentrations in the tumor tissue in a 2-step delivery protocol due to the leaking of the drug from its liposomal carrier providing an explanation for the observed lack of efficacy.

MiR-218 impairs tumor growth and increases chemo-sensitivity to cisplatin in cervical cancer

MicroRNAs are noncoding RNA molecules of 18–25 nucleotides that regulate gene expression at the post-transcriptional levels. Recent data revealed that miR-218 played key roles in tumor metastasis. Here, we described the regulation and function of miR-218 in cervical cancer. Overexpression of miR-218 reduced the proliferation of the human cervical cancer cell line HeLa and induced cell apoptosis through the AKT-mTOR signaling pathway. In addition, it forced expression of miR-218 suppressed tumor growth in the orthotopic mouse model of HeLa cells. Furthermore, miR-218 increased chemosensitivity to cisplatin (CDDP) in vitro. Our results indicated that targeting miR-218 may provide a strategy for blocking the development of cervical cancer.

Lyso-thermosensitive liposomal doxorubicin: an adjuvant to increase the cure rate of radiofrequency ablation in liver cancer

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer death worldwide. No more than 30% of HCC patients are considered suitable for curative treatment because of tumor size and severity of liver impairment, among other factors. Radiofrequency ablation (RFA) monotherapy can cure small (<3 cm) HCC tumors. An adjuvant that interacts synergistically with RFA might enable curative therapy for many HCC patients with lesions >3 cm. Lyso-thermosensitive liposomal doxorubicin (LTLD) consists of the heat-enhanced cytotoxic doxorubicin within a heat-activated liposome. LTLD is infused intravenously prior to RFA. When heated to >39.5°C, LTLD releases doxorubicin in high concentrations into the tumor and the tumor margins. The RFA plus LTLD combination has shown a statistically significant dose-response effect for time to treatment failure in a Phase I trial in which most subjects (62.5%) had tumors >3 cm. RFA plus LTLD is currently being evaluated in a 600-patient randomized, double-blind, dummy-controlled trial.

Lyso-thermosensitive liposomal doxorubicin: a novel approach to enhance efficacy of thermal ablation of liver cancer

BACKGROUND

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer death worldwide. No more than 30% of HCC patients receive curative treatment. Factors limiting curative therapy include tumor size and degree of liver impairment.

OBJECTIVE

To develop a cure for medium (3.1-5.0 cm) and large (>5 cm) tumors in seriously impaired livers.

METHOD

Combine radiofrequency ablation (RFA) with lyso-thermosensitive liposomal doxorubicin (LTLD).

RESULTS/CONCLUSIONS

RFA is used safely in patients with medium/large tumors and severe liver impairment; unclear tumor margins limit its curative efficacy. LTLD concentrates in the liver, where the anti-HCC chemotherapeutic, doxorubicin, is released into tumor margins by hyperthermia. RFA/LTLD can treat Child-Pugh class A-B patients with tumors up to 7 cm, a substantial increase in curable patients.

Pharmacokinetics of paclitaxel administered by hyperthermic retrograde isolated lung perfusion techniques

OBJECTIVE

Although paclitaxel is widely used as a systemic agent for the treatment of solid tumors, limited information is available concerning administration of this taxane by regional techniques. The present study was undertaken to evaluate the pharmacokinetics and acute toxicity of paclitaxel administered by hyperthermic retrograde isolated lung perfusion techniques to ascertain its potential for the regional therapy of unresectable pulmonary neoplasms.

METHODS

Adult sheep underwent 90 minutes of retrograde isolated lung perfusion with escalating doses of paclitaxel and moderate hyperthermia using a protein-free, oxygenated extracorporeal circuit and a steady perfusion pressure of 14 to 16 mm Hg. An additional animal received paclitaxel by means of 1-hour central venous infusion. Paclitaxel concentrations in lung tissues, perfusates, and systemic circulation were determined by high-performance liquid chromotography techniques. Cytotoxicity of paclitaxel in cancer cells and in normal human bronchial epithelial cells was evaluated in vitro using 4, 5-dimethylthiazo-2-yl-25-dipagnyl tetrazolium bromide assays. Lung tissues were examined by hematoxylin-and-eosin techniques.

RESULTS

Paclitaxel concentrations (maximum concentration and area under the plasma concentration time curve) in perfused tissues increased with escalating perfusate doses. Uptake of drug into lung parenchyma appeared saturable at high paclitaxel exposure; a substantial pharmacokinetic advantage was observed. Paclitaxel concentrations in systemic circulation were undetectable or exceedingly low after perfusion. Histopathologic examination of lung tissues harvested 3 hours after completion of isolated lung perfusion revealed no immediate toxicity, even at a paclitaxel exposure 20-fold higher than that achievable after 1 hour of intravenous administration at the maximum tolerable dose in human subjects. Moderate hyperthermia enhanced paclitaxel-mediated cytotoxicity 5- to 100-fold in cultured cancer lines. No paclitaxel toxicity was observed in cultured normal human bronchial epithelial cells after exposure to paclitaxel under normothermic or hyperthermic conditions.

CONCLUSIONS

These data support further evaluation of paclitaxel administered by hyperthermic retrograde isolated lung perfusion techniques for the treatment of unresectable malignant pulmonary tumors.

Hyperthermic enhancement of cytotoxicity and increased uptake of cis-diamminedichloroplatinum(II) in cultured human esophageal cancer cells

Thermal enhancement of cytotoxicity of cis-diamminedichloroplatinum(II) (CDDP) has been well recognized and applied clinically to chemotherapy of various malignancies, but its fundamental mechanism remains to be elucidated. In order to obtain a clue to this mechanism, we analyzed the effect of hyperthermia on the uptake and subsequent distribution of [195mPt]CDDP in two lines of esophageal cancer cells (KYSE-150 and KYSE-170) established from clinical patients. First, we observed a significant increase in [195mPt]CDDP uptake by both types of cells at increasingly higher temperatures. The incorporated CDDP was distributed between the nucleus and the cytosol at a ratio of approximately 3:1, and the ratio remained the same at various temperatures. The CDDP was found in all four molecular fractions, i.e., DNA, RNA, protein, and TCA-soluble, with a slight preference for DNA at higher temperatures. Enhancement of cytotoxicity required simultaneous, and not sequential, treatments with CDDP and hyperthermia; hyperthermia after CDDP treatment increased the efflux of CDDP from the cells, and rather reduced the cytotoxicity of CDDP. These results suggest that thermal enhancement of the cytotoxicity of CDDP is caused mainly by acceleration of the drug entry into the cell, probably due to increased permeability, and a consequent increase in the amount of CDDP binding to DNA. This mechanism gives support for clinical trial of simultaneous treatment with CDDP and hyperthermia.