Interstitial laser photochemotherapy with new anthrapyrazole drugs for the treatment of xenograft tumors

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.

Retention of intratumor injections of cisplatinum in murine tumors and the impact on laser thermal therapy for cancer treatment

Recent studies using murine models of human squamous cell carcinoma (SCCA) have revealed a significant improvement in survival and cure rate of animals transplanted with human SCCA when treated with a combination of intratumor injections of chemotherapy and laser induced thermal therapy (LITT). These preliminary results suggest that this novel combination therapy may lead to improved clinical response compared to either treatment modality alone. Using a murine model of human SCCA we investigated two different modes of intratumor injection of cisplatin: a sustained-release cisplatin gel implant (CDDP/gel) versus cisplatin in solution (CDDP) at varying doses (range 1-3 mg/ml). In addition, we tested CDDP/gel combined with LITT. Results showed optimal drug concentration (30-300 nM) at tumor margins up to 4 h after injection of CDDP/gel implant compared to 3 nM at 5 min after injection with CDDP solution. Combined CDDP/gel and laser therapy significantly decreased tumor volume (P<0.05), with recurrence in only 25% of animals tested, compared to 78% tumor regrowth after LITT alone. These results suggest that laser chemotherapy may be an effective treatment for head and neck SCCA.

Intratumor injections of cisplatin and laser thermal therapy for palliative treatment of recurrent cancer

OBJECTIVE

The aim of this work was to report initial findings on the clinical application of intratumor injection of cisplatin in a gel (CDDP/gel) combined with laser-induced thermal therapy (LITT) for cancer treatment in a single patient with advanced stage disease.

BACKGROUND DATA

LITT with the neodymium:yttriumaluminum- garnet (Nd:YAG) laser via fiberoptics is a precise, minimally invasive alternative for thermoablation of unresectable or recurrent head and neck neoplasms, but recurrence is often seen at the treatment margins. Combining intratumor chemotherapy with interstitial laser should be most effective using drugs with thermally enhanced toxicity, such as cisplatin. The CDDP/gel therapeutic implant was expected to retain a higher concentration of cisplatin in the tumor margins for improved LITT treatment of the patient presented.

METHODS

In this case report, the cisplatin dose was 0.25 mL gel/cm(3) tumor volume (20 mg of CDDP) followed by LITT (Nd:YAG laser, 50 W, PD = 2,200 J/cm(2)) after the chemotherapy session.

RESULTS

The patient responded with local tumor eradication, and no signs of systemic toxicity were observed related to this therapy. However, the patient developed progressive metastatic disease in the lungs and died 2.5 months later.

CONCLUSIONS

This is a report of a patient with an accessible solid tumor who was treated with intratumor injection of CDDP/gel followed by LITT, which proved to be feasible. Based on preclinical evidence obtained at UCLA and the results of this study, we are encouraged to continue our refinement of LITT combined with chemotherapy for cancer treatment.

Bactericidal effects of toluidine blue-mediated photodynamic action on Vibrio vulnificus

Vibrio vulnificus is a gram-negative, highly invasive bacterium responsible for human opportunistic infections. We studied the antibacterial effects of toluidine blue O (TBO)-mediated photodynamic therapy (PDT) for V. vulnificus wound infections in mice. Fifty-three percent (10 of 19) of mice treated with 100 microg of TBO per ml and exposed to broad-spectrum red light (150 J/cm(2) at 80 mW/cm(2)) survived, even though systemic septicemia had been established with a bacterial inoculum 100 times the 50% lethal dose. In vitro, the bacteria were killed after exposure to a lower light dose (100 J/cm(2) at 80 mW/cm(2)) in the presence of low-dose TBO (0.1 microg/ml). PDT severely damaged the cell wall and reduced cell motility and virulence. Cell-killing effects were dependent on the TBO concentration and light doses and were mediated partly through the reactive oxygen species generated during the photodynamic reaction. Our study has demonstrated that PDT can cure mice with otherwise fatal V. vulnificus wound infections. These promising results suggest the potential of this regimen as a possible alternative to antibiotics in future clinical applications.

Intratumoral hypericin and KTP laser therapy for transplanted squamous cell carcinoma

OBJECTIVES/HYPOTHESIS

To test intratumoral photodynamic therapy (IPDT) as a new treatment for squamous cell carcinoma in a preclinical tumor model.

STUDY DESIGN AND METHODS

Human P3 squamous carcinoma cells were transplanted subcutaneously in athymic nude mice and allowed to grow into 300- to 500-mm3 tumors. Hypericin dye at 1 microg/gm of body weight was injected intratumorally (IT) or intravenously (IV). After 4 hours hypericin biodistribution was assessed in ethanol extracts from tissues by fluorescence spectroscopy. IPDT also was tested by KTP laser fiberoptic insertion in tumors 4 hours after IT dye injection compared to KTP532 laser therapy alone (532 nm, 1W, 40-60 J, 0.6-mm fiber).

RESULTS

Hypericin concentration in tissues was as follows: (IT vs. IV) for tumors (3660 vs. 135 ng dye/gm tissue), lung (760 vs. 6345), liver (75 vs. 935), blood (65 vs. 480) compared to skin (465 vs. 110) or muscle (335 vs. 80) adjacent to the squamous cell tumors. Four hours after dye injection, the tumor exhibited bright orange fluorescence when excited by KTP 532-nm green laser light. The IPDT-treated tumors had a 3.32+/-0.32-mm radius of cell destruction when H&E-stained sections were examined compared with 2.5+/-0.38 mm for the laser only control group (n = 10, P = .003).

CONCLUSIONS

This pilot study indicates laser IPDT with hypericin induces a significant increase in tumor necrosis compared with laser alone and may be useful as a less invasive adjuvant treatment for recurrent or inoperable human squamous cell cancers of the head and neck.

Improved photochemotherapy of malignant cells with daunomycin and the KTP laser

Laser photochemotherapy of malignancies may become an effective palliative treatment for advanced had and neck cancer using light-sensitive, chemotherapeutic drugs activated in tumors via interstitial laser fiberoptics. Previously, it was reported that cultured human P3 squamous cells incubated 2 hours with daunomycin (Dn) exhibited tenfold enhanced cytotoxicity after exposure to argon laser light at 514 nm. This short-term uptake leads to drug localization in cytoplasmic and membrane sites prior to nuclear accumulation and daunomycin topoisomerase inhibition. In the current study phototoxicity of Dn-sensitized human cancer cells was tested using broad-spectrum white light compared to monochromatic green-wavelength light. Drug uptake and laser energy levels were optimized for maximum synergy. To test light-enhanced chemotherapy in vitro, the kinetics of cell uptake and toxicity of daunomycin was measured at 1, 2, and 5 microg/ml in three human tumor cell lines: P3 squamous-cell carcinoma, M26 melanoma, and TE671 fibrosarcoma. After 2 hr Dn uptake, all cell lines were tested for phototherapy response by exposure to 300- to 900-nm visible light from a xenon lamp or monochromatic 532-nm green light from a KTP laser. When the KTP laser output was varied from 0 to 120 Joules in Dn-sensitized tumor cells, a linear phototherapy response was seen with energy as low as 12 J inducing drug phototoxicity. These results provide evidence that daunomycin cytotoxicity is enhanced when exposed to 532-nm laser illumination in the three tumor types tested and confirm that the response is related to both energy level and drug dose.

Cisplatinum and interstitial laser therapy for advanced head and neck cancer: a preclinical study

BACKGROUND AND OBJECTIVE

Direct intratumor injection of cisplatinum (CDDP) and laser therapy were tested for improved treatment of squamous cell carcinoma (SCCA).

STUDY DESIGN/MATERIALS AND METHODS

Human SCCA tumors were grown as s.c. transplants in nude mice and injected with CDDP (0.4-1.2 mg/gm) in water or in collagen-based gel carrier with epinephrine (epi-gel), followed by interstitial laser therapy (ILT) via 0.6 mm fiberoptics (532 nm/300 J).

RESULTS

Tumors injected with CDDP epi-gel exhibited a partial response with 2-4-fold tumor growth delay, compared to aqueous drug or untreated SCCA transplants during 10-week follow-up. Combined drug and laser therapy significantly decreased tumor volume with recurrence in only 25% (2/8) of animals tested, compared to 66% tumor regrowth (10/15) after ILT alone.

CONCLUSION

These initial results suggest laser chemotherapy may become an effective treatment for advanced head and neck cancer.

Laser and cisplatinum for treatment of human squamous cell carcinoma

OBJECTIVE

Interstitial laser therapy (ILT) with the neodymium:yttrium-aluminum-garnet (Nd:YAG) (1064 nm) laser via fiberoptics is becoming a more precise, minimally invasive alternative for thermoablation of unresectable or recurrent head and neck neoplasms, but recurrence is often seen at the margin. Combining intratumor chemotherapy with interstitial laser should be most effective using drugs activated by thermal energy. The objective of the current study was to test intratumor cisplatinum (cis-diaminedichloroplatinum [CDDP]) injections given in conjunction with laser therapy as an experimental approach for improved treatment of squamous cell carcinoma (SCC).

METHODS

Human SCC tumors were grown as subcutaneous transplants in nude mice and injected with CDDP (0.4 to 1.2 mg/g) in water or in collagen-based gel carrier with epinephrine (epi-gel) followed by ILT via 0.6-mm fiberoptics coupled to an Nd:YAG laser (1064 nm/180 J).

RESULTS

Tumors injected with CDDP epi-gel exhibited a partial response with two- to fourfold tumor delay compared with aqueous drug or untreated SCC transplants during 10 weeks' follow-up. Combined drug and laser therapy significantly (P < .01) decreased tumor volume, with recurrence in only 25% of animals tested compared with 78% tumor regrowth after ILT alone.

CONCLUSION

These initial results suggest that laser chemotherapy may become an effective treatment for advanced head and neck cancer.

Anthrapyrazoles and interstitial laser phototherapy for experimental treatment of squamous cell carcinoma

Interstitial laser therapy (ILT) is an effective palliative treatment for advanced head and neck cancer, but recurrence often is seen at the margin. The objective of the current study was to test combined drug and laser therapy as an experimental approach for improved treatment of human squamous cell carcinoma (SCCA). Human SCCA tumor transplants were grown in nude mice and injected with the photosensitive anthrapyrazole CI-941 before ILT. Intralesional drug injections alone at levels ranging from 60 to 1200 microg/gm of tumor induced a growth delay at the higher doses, but recurrence was seen in all 35 tumors tested. SCCA tumor transplants injected with 240 microg/gm CI-941 followed after 4 hours by ILT with the KTP532 laser led to a complete response rate of 72% (21/29) compared with 45% (13/29) for ILT alone. Laser chemotherapy was a significant improvement compared with ILT when partial and complete responses were combined (P < 0.03). The results provide preclinical evidence that laser chemotherapy may become a useful minimally invasive treatment for advanced squamous cell carcinoma of the head and neck.