Jacques Soudant

Metastatic head and neck malignancy treated using MRI guided interstitial laser phototherapy: An initial case report

Interstitial laser phototherapy (ILP) guided by magnetic resonance imaging (MRI) may become an attractive adjunctive modality for the treatment of deep and surgically inaccessible tumors of the head and neck when accurate methods of laser dosimetry and “real‐time” monitoring techniques with the MRI are introduced. We recently demonstrated in ex vivo and in vivo models, a linear relationship between levels of laser energies, thermal profiles, MR signal intensity changes, and histopathological tissue damage. Results of treatment in a patient with an unresectable large right jugulodigastric metastatic squamous carcinoma using new approach of MRI guided ILP are now reported. The patient complained of significant right‐sided neck pain and headaches secondary to a rapidly growing metastatic lymphadenopathy which recurred after previous surgery, radiation, and chemotherapy. Two treatment sessions were used at an interval of 2 weeks. Each treatment was performed in the MRI suite under heavy sedation. Using a 600‐μm bare fiber of the Nd:YAG laser implanted interstitially under MR guidance, the metastatic node was treated at three sites. T1‐ and T2‐weighted images were performed prior to, immediately after, 24 and 48 hours, and 4, 5, 7, 9, 16, and 25 days post‐treatment. Successful relief of pain and growth arrest of this node was observed after the second treatment and at the 3‐month follow‐up. These results demonstrate that this technique of ILP guided by MRI may be feasible in humans, and will become clinically practical when appropriate methods of dosimetry and instrumentation are developed.

Hypericin: A New Laser Phototargeting Agent for Human Cancer Cells†‡

Laser activation of anthracycline‐related drugs combines chemotherapy with photoablation for improved treatment. Hypericin, a structurally related anthraquinone, was tested for laser activation and cytotoxicity in human cancer cells. Viability of P3 squamous cell carcinoma cells incubated with 1 to 20μg/mL hypericin was reduced by more than 95% after 1 minute exposure at 4°C to an argon laser (514 nm, 5 W), a KTP‐532 laser (532 nm, 5 W), or a 20‐A xenon lamp. Viability was reduced over 90% in six human carcinoma, sarcoma, and melanoma cell lines by this combined treatment, but only trace toxicity was seen after separate exposure to hypericin or light alone. These results show that hypericin is a sensitive agent for phototherapy of human cancer cells in vitro and indicate that this drug may be useful for tumor targeting via minimally invasive imaging‐guided laser fiberoptics.

Hypericin uptake in rabbits and nude mice transplanted with human squamous cell carcinomas: study of a new sensitizer for laser phototherapy.

Tissue uptake and biodistribution of hypericin was measured in rabbits and in nu/nu mice xenografted with P3 human squamous cell carcinoma to assess the value of this dye as an in vivo sensitizer for laser photoinactivation of solid tumors. Hypericin has absorption maxima at 545 and 590 nm with a fluorescence emission peak at 640 nm in ethanol. Dye uptake after intravenous injection was tested at 4 and 24 hours in rabbit tissues by ethanol extraction and quantitative fluorescence spectrophotometry. Maximum dye levels were seen at 4 hours in most vascular organs with lung having fivefold higher uptake than spleen followed by liver, blood, and kidney. Mice were examined after 2, 4, 6, 8, and 24 hours and after 3 and 7 days for dye uptake. The peak concentration of hypericin in murine organs was reached at 4 hours with uptake per gram of tissue as follows: lung>spleen>liver>blood>kidney>heart>gut>tumor>stomach>skin>muscle>brain. Elimination of hypericin was rapid in most murine organs with residual dye under 10% of maximum by 7 days compared to 25% to 30% retention for the squamous cell tumors and several normal tissues. These results suggest that hypericin may be a useful photosensitizer for KTP/532 laser interstitial therapy of human cancer.

Dynamic MRI-guided interstitial laser therapy: A new technique for minimally invasive surgery

Interstitial laser therapy (ILT) is a promising therapeutic technique in which laser energy is delivered percutaneously to various depths in tissue. In this study, the authors compared high‐speed magnetic resonance imaging (MRI) of ILT in tissues during treatment with post‐treatment histopathologic specimens. The use of 5‐second MRI scans allowed detection of thermal damage by the 1064‐nm neodym‐ium:yttrium‐aluminum‐garnet laser in ex vivo liver and brain tissues. These tissues were treated by ILT with 20 W of laser output for 5 to 30 seconds via a 600‐μm fiberoptic inserted 1 cm into the specimens at a power density of 7 kW/cm2 at the tip of the bare fiber.

Laser dyes for experimental phototherapy of human cancer: Comparison of three rhodamines

The mitochondrial dye Rhodamine 123 (Rh‐123) has been shown to be an effective photosensitizer for argon‐laser irradiation of some types of human cancer cells in vitro. We reported that 514.5‐nm laser illumination of Rh‐123 sensitized human melanoma, and squamous carcinoma cells strongly inhibited tumor‐cell proliferation as measured by decreased 3H‐thymidine (3H‐T) uptake in vitro and may eradicate some tumors when grown as transplants in nude mice. However, several other human tumors were resistant to Rh‐123 laser therapy in vitro and in vivo. In the current study, it was possible to obtain 100‐ to 1000‐fold increased sensitivity to 514.5‐nm laser illumination by replacement of Rh‐123 with the cationic rhodamine dyes Rh‐3G and Rh‐6G. Cell viability was decreased over 95% and 3H‐T incorporation reduced at least 80% by laser phototherapy after sensitizing tumor cells with 1 μg/mL Rh‐123, 0.01 μg/mL Rh‐3G, or 0.001 μg/mL Rh‐6G. However, Rh‐123 alone did not decrease 3H‐T uptake significantly unless present at over 10‐ to 100‐fold higher levels than Rh‐3G, respectively. The tumor cell dye uptake level was measured by N‐butanol extraction and absorption scans at 400 to 600 nm. The results revealed that dye uptake was more rapid, and retention of Rh‐3G and Rh‐6G was 5‐ to 10‐fold higher than for Rh‐123 in the human tumor cells. The data suggest that Rh‐3G and Rh‐6G may be highly sensitive chromophores for laser phototherapy of human cancer cells.

Future directions of laser phototherapy for diagnosis and treatment of malignancies: Fantasy, fallacy, or reality?

A new and highly promising adjunctive modality for the diagnosis and therapy of malignancies is under development using lasers and tumor targeting dyes. To reach the eventual goal of clinical treatment, several current “fantasies and fallacies” regarding laser applications in medicine must be identified and their problems clearly outlined. A multidisciplinary scientific approach is also required to enable the clinical practicality of this laser targeting approach. Many new dyes and laser wavelengths are being tested to improve specific tumor uptake and/or retention, lower systemic toxicity, increase tissue penetration, and identify fluorochromes with synergistic properties to further enhance laser tumoricidal effects. Rapid technological advancements in magnetic resonance imaging may now provide an extremely sensitive way to detect and monitor laser‐tissue effects, and allow efficient interstitial laser phototherapy of deep and sometimes inaccessible tumors. The current and future prospectives of the emerging field of laser phototherapy are described.

Laser Photochemotherapy With Anthracyclines on Cultured Human Squamous Carcinoma Cells

A new treatment for cancer has been tested in vitro using light‐sensitive anthracyclines followed by laser photoactivation, as described by several investigators. We previously reported 10‐fold enhanced laser killing after 2 hours of incubation with daunomycin by cultured human carcinoma cells. This short‐term uptake leads to drug localization in cytoplasmic and membrane sites prior to nuclear accumulation and topoisomerase inhibition. In the present study, daunomycin was incubated for 2 or 24 hours with P3 squamous carcinoma cells to directly compare cytoplasmic vs. nuclear drug targeting before and after KTP‐532 laser activation. Monolayer cultures of the P3 cells sensitized with daunomycin for 2 hours, then chilled (4°C), and exposed to the KTP laser (532 nm, 94.2 J/cm2) had a 2‐ to 10‐fold increased therapeutic response compared with drug or laser alone when measured by MTT tetrazolium assays. After 24 hours of incubation with daunomycin, the chemotherapeutic response of P3 tumor cells was amplified 2‐fold by laser exposure. The results suggest that daunomycin and laser treatment can be combined for improved therapy of human cancer.

Combined intratumor cisplatinum injection and Nd:YAG laser therapy

Objectives/Hypothesis: Interstitial laser therapy (ILT) has become useful for tumor palliation in patients with advanced head and neck cancer. Cisplatinum chemotherapy also is a frequent adjuvant treatment for recurrent tumors, but systemic toxicity limits application. Intratumor cisplatinum injection combined with ILT may improve therapy of these recurrent tumors with reduced toxicity. Study Design: Prospective. Tumor transplants were injected with cisplatinum in a gel implant before ILT to evaluate treatment response and toxicity in a preclinical study. Methods: UCLA‐P3 human squamous cell carcinoma tumors were grown as subcutaneous transplants in nude mice and treated by intratumor injection of 2 mg/mL cisplatinum in a slow‐release, collagen‐based gel carrier 4 hours before interstitial implantation of Nd:YAG laser fiberoptics to induce local tumor hyperthermia. Treatment efficacy and toxicity were followed for 12 weeks after combined drug and laser therapy compared with ILT alone. Results: Combined cisplatinum gel and ILT was a significant improvement (P < .01 by chi‐square test) and induced 57% complete responses without regrowth in 21 transplanted tumors compared with only 24% in 21 tumors after ILT alone during 12‐week follow‐up. Recurrences in both cases appeared to result from nonuniform laser energy delivery within tumors via the implanted fiberoptic tip. Conclusions: The results of this experimental combined cisplatinum and ILT study suggest it may be possible to improve treatment of advanced head and neck cancer by intratumor injection of gel implants containing the drug followed by interstitial Nd:YAG laser hyperthermia.

The Synergistic Effects of Rhodamine-123 and Merocyanine-540 Laser Dyes on Human Tumor Cell Lines: A New Approach to Laser Phototherapy

Many new photosensitizers and laser wavelengths are being tested to improve photodynamic therapy by enhancing specific tumor uptake and/or retention, lowering systemic toxicity, and increasing laser tissue penetration. In this study the potential synergistic effects of rhodamine-123 (Rh-123) and merocyanine-540 (MC-540) sensitization of human tumor cell lines after laser exposure were explored. In a first series of experiments, the kinetics of uptake of Rh-123 and M-540 were tested on three human leukemia cell lines (K562, RAJI, 729HF2), P3 squamous carcinoma, and M26 melanoma. Our results demonstrate a clear difference in the rate and amount of uptake of MC-540 (K562 > P3 > RAJI > 729HF2 > M26) and Rh-123 (P3 > RAJI > 729HF2 > K562 > M26) by these cell lines. In a second series of experiments, M26 tumor cells were sensitized with either Rh-123 (1 μg/ml) or with MC-540 (20 μg/ml) alone or with a combination of the two dyes for 60 minutes, then exposed to the argon (514.5 nm) laser at nonthermal energy levels. Our results demonstrate a significant enhancement of the tumoricidal effects of the laser on M26 carcinoma cells after sensitization with both dyes together (MC-540 and Rh-123) when compared to each dye alone. As with combination antibiotherapy, the synergistic effects of two laser dyes that have different intracellular targeting sites appear to enhance tumoricidal effects significantly after exposure to a matching laser wavelength. The data provide evidence for effective laser phtototherapy by dye synergy.

Near "real" time magnetic resonance images as a monitoring system for interstitial laser therapy: experimental protocols

The failure rate of cancer treatment remains unacceptably high, still being a leading cause of mortality in adults and children despite major advances over the past 50 years in the fields of surgery, radiation therapy and, more recently, chemo and immunotherapy. Surgical access to some deep tumors of the head and neck and other areas often require extensive dissections with residual functional and cosmetic deformities. Repeated treatment is not possible after maximum dose radiotherapy and chemotherapy is still limited by its systemic toxicity. An attractive solution to these problems would be the development of a new adjunctive method combining the best features of interstitial laser therapy for selective tumor destruction via minimally invasive techniques for access and 3-D magnetic resonance imaging (MRI) as a monitoring system for laser-tissue interactions. Interstitial laser therapy (ILT) via fiberoptics allow laser energy to be delivered directly into deeper tissues. However, this concept will become clinically useful only when noninvasive, accurate, and reproducible monitoring methods are developed to measure energy delivery to tissues. MRI has numerous advantages in evaluating the irreversible effects of laser treatment in tissues, since laser energy includes changes not only in the thermal motions of hydrogen protons within the tissue, but also in the distribution and mobility of water and lipids. These techniques should greatly improve the use of ILT in combination with MRI to allow treatment of deeper, more difficult to reach tumors of head and neck and other anatomical areas with a single needle stick.