Optical integrating balloon device for photodynamic therapy

Association of 5-aminolevulinic acid fluorescence guided resection with photodynamic therapy in recurrent glioblastoma: a matched cohort study

PURPOSE

Glioblastoma is a malignant and aggressive brain tumour that, although there have been improvements in the first line treatment, there is still no consensus regarding the best standard of care (SOC) upon its inevitable recurrence. There are novel adjuvant therapies that aim to improve local disease control. Nowadays, the association of intraoperative photodynamic therapy (PDT) immediately after a 5-aminolevulinic acid (5-ALA) fluorescence-guided resection (FGR) in malignant gliomas surgery has emerged as a potential and feasible strategy to increase the extent of safe resection and destroy residual tumour in the surgical cavity borders, respectively.

OBJECTIVES

To assess the survival rates and safety of the association of intraoperative PDT with 5-ALA FGR, in comparison with a 5-ALA FGR alone, in patients with recurrent glioblastoma.

METHODS

This article describes a matched-pair cohort study with two groups of patients submitted to 5-ALA FGR for recurrent glioblastoma. Group 1 was a prospective series of 11 consecutive cases submitted to 5-ALA FGR plus intraoperative PDT; group 2 was a historical series of 11 consecutive cases submitted to 5-ALA FGR alone. Age, sex, Karnofsky performance scale (KPS), 5-ALA post-resection status, T1-contrast-enhanced extent of resection (EOR), previous and post pathology, IDH (Isocitrate dehydrogenase), Ki67, previous and post treatment, brain magnetic resonance imaging (MRI) controls and surgical complications were documented.

RESULTS

The Mantel-Cox test showed a significant difference between the survival rates (p = 0.008) of both groups. 4 postoperative complications occurred (36.6%) in each group. As of the last follow-up (January 2024), 7/11 patients in group 1, and 0/11 patients in group 2 were still alive. 6- and 12-months post-treatment, a survival proportion of 71,59% and 57,27% is expected in group 1, versus 45,45% and 9,09% in group 2, respectively. 6 months post-treatment, a progression free survival (PFS) of 61,36% and 18,18% is expected in group 1 and group 2, respectively.

CONCLUSION

The association of PDT immediately after 5-ALA FGR for recurrent malignant glioma seems to be associated with better survival without additional or severe morbidity. Despite the need for larger, randomized series, the proposed treatment is a feasible and safe addition to the reoperation.

INtraoperative photoDYnamic Therapy for GliOblastomas (INDYGO): Study Protocol for a Phase I Clinical Trial

BACKGROUND

Glioblastoma (GBM) is characterized by marked proliferation, major infiltration, and poor prognosis. Despite current treatments, including surgery, radiation oncology, and chemotherapy, the overall median survival is 15 mo and the progression-free survival is 7 to 8 mo. Because of systematic relapse of the tumor, the improvement of local control remains an issue. In this context, photodynamic therapy (PDT) may offer a new treatment modality for GBM.

OBJECTIVE

To assess the feasibility of intraoperative PDT early after surgical resection of GBM without unacceptable and unexpected toxicities.

METHODS

The INDYGO clinical trial (INtraoperative photoDYnamic Therapy for GliOblastomas) treatment will be carried out in addition to the current standard of care (SOC) of glioblastoma: maximum resection surgery followed by concomitant radio-chemotherapy and adjuvant chemotherapy. PDT treatment will be delivered during surgery early, after the fluorescence-guided resection. Immunological responses and biomarkers will also be investigated during the follow-up. A total of 10 patients will be recruited during this study.

EXPECTED OUTCOMES

Clinical follow-up after the SOC with PDT is expected to be similar (no significant difference) to the SOC alone.

DISCUSSION

This INDYGO trial assesses the feasibility of intraoperative 5-aminolevulinic acid PDT, a novel seamless approach to treat GBM. The technology is easily embeddable within the reference treatment at a low-incremental cost. The safety of this new treatment modality is a preliminary requirement before a multicenter randomized clinical trial can be further conducted to assess local control improvement by treating infiltrating and nonresected GBM cells.

Light Sources and Dosimetry Techniques for Photodynamic Therapy

Effective treatment delivery in photodynamic therapy (PDT) requires coordination of the light source, the photosensitizer, and the delivery device appropriate to the target tissue. Lasers, light-emitting diodes (LEDs), and lamps are the main types of light sources utilized for PDT applications. The choice of light source depends on the target location, photosensitizer used, and light dose to be delivered. Geometry of minimally accessible areas also plays a role in deciding light applicator type. Typically, optical fiber-based devices are used to deliver the treatment light close to the target. The optical properties of tissue also affect the distribution of the treatment light. Treatment light undergoes scattering and absorption in tissue. Most tissue will scatter light, but highly pigmented areas will absorb light, especially at short wavelengths. This review will summarize the basic physics of light sources, and describe methods for determining the dose delivered to the patient.

A novel device for intraoperative photodynamic therapy dedicated to glioblastoma treatment

AIM

Photodynamic therapy (PDT) appears to be a valuable new treatment modality for cancer therapy. Studies have reported successful application of PDT for glioblastoma. Here, we introduce a new device dedicated to intraoperative PDT delivered early after fluoro-guided resection combined with a transfer function that determines the treatment time based on the size of the surgical resection cavity.

MATERIALS & METHODS

First, we describe the device, which is composed of a trocar, a balloon filled with a diffusing solution, and a fiber guide in which a cylindrical light diffuser is inserted. Ex vivo experiments were performed to measure the fluence rate inside biological tissues. A calibration factor was defined to convert power measurements into fluence rate values. Calf brains were used to simulate light propagation in human brain tissue, and the photosensitizer administration effect on optical properties was discussed. The temperature elevation during illumination was evaluated.

RESULTS

Light power was measured in tissues surrounding the device during ex vivo experiments. Using the previously characterized calibration factor, power measurements were converted to fluence rate values to obtain the transfer function. No thermal elevation was observed during a 2-h temperature test, and the impact of protoporphyrin IX on brain optical properties was considered negligible.

CONCLUSION

A discussion of experimental precision is presented. The light duration determined by the abacus had a standard deviation of <1 min. This value is weak compared with the total illumination time necessary to treat one patient. The main advantage of our device lies in its straightforward implementation of intraoperative PDT for neurosurgery with acceptable dosimetry and easy treatment time.

Photodynamic therapy for the treatment of atherosclerotic plaque: Lost in translation?

Acute coronary syndrome is a life-threatening condition of utmost clinical importance, which, despite recent progress in the field, is still associated with high morbidity and mortality. Acute coronary syndrome results from a rupture or erosion of vulnerable atherosclerotic plaque with secondary platelet activation and thrombus formation, which leads to partial or complete luminal obstruction of a coronary artery. During the last decade, scientific evidence demonstrated that when an acute coronary event occurs, several nonculprit plaques are in a "vulnerable" state. Among the promising approaches, several investigations provided evidence of photodynamic therapy (PDT)-induced stabilization and regression of atherosclerotic plaque. Significant development of PDT strategies improved its therapeutic outcome. This review addresses PDT's pertinence and major problems/challenges toward its translation to a clinical reality.

A deterministic approach to the adapted optode placement for illumination of highly scattering tissue

A novel approach is presented for computing optode placements that are adapted to specific geometries and tissue characteristics, e.g., in optical tomography and photodynamic cancer therapy. The method is based on optimal control techniques together with a sparsity-promoting penalty that favors pointwise solutions, yielding both locations and magnitudes of light sources. In contrast to current discrete approaches, the need for specifying an initial set of candidate configurations as well as the exponential increase in complexity with the number of optodes are avoided. This is demonstrated with computational examples from photodynamic therapy.

Pre-clinic study of uniformity of light blanket for intraoperative photodynamic therapy

A large-size blanket composed of the parallel catheters and silica core side glowing fiber is designed to substitute the hand-held point source in the photodynamic therapy treatment (PDT) of the malignant pleural or intraperitoneal diseases. It produces a reasonably uniform field for effective light coverage and is flexible to conform to anatomic structures in intraoperative PDT. The size of the blanket is 30cm×20cm. The light blanket composed of several PVC layers and a series of parallel catheters attached on both sides of the intralipid layer of 0.2% concentration. On one side of the intralipid layer, the parallel fiber catheters were attached using thermal sealing technique. On the other side, the parallel detect catheters were attached along the perpendicular direction. 0.1mm aluminum foil was used to construct the reflection layer to enhance the efficiency of light delivery. The long single side-glowing fiber goes through the fiber catheters according to the specific fiber pattern design. Compared with the prototype of the first generation, the new design is more cost-efficient and more applicable for clinical applications. The light distribution of the blanket was characterized by scanning experiments which were performed in flatness and on the curved surface of tissue body phantom. The fluence rate generated by the blanket can meet requirements for the light delivery in pleural or intraperitoneal (IP) PDT. Taking the advantage of large coverage and flexible conformity, it has great value to increase the reliability and consistency of PDT.

Novel flexible light diffuser and irradiation properties for photodynamic therapy

Many current light diffusers for photodynamic therapy are inflexible, and the applied light dose is difficult to adjust during treatment, especially on complex body surfaces. A thin and flexible luminous textile is developed using plastic optical fibers as a light distributor. The textile diffuser is evaluated for flexibility, irradiance, brightness distribution, and temperature rise with a 652-nm laser set to 100 mW. The bending force of the textile diffuser resembles a defined optical film. On the textile surface, an average output power of 3.6+/-0.6 mWcm(2) is measured, corresponding to a transmission rate of 40+/-3.8% on an area of 11 cm(2). Aluminum backing enhances the irradiance to the face (treatment side). The measured brightness distribution seems to lie within a range similar to other photodynamic therapy (PDT) devices. A power setting of 100 mW increases the temperature of the textile diffuser surface of up to 27 degrees C, and 1 W raises the temperature above 40 degrees C. Results confirm that the flexible textile diffuser supplies suitable radiation for low fluence rate photodynamic therapy on an area of several cm(2).

Preclinical Comparison of mTHPC and Verteporfin for Intracavitary Photodynamic Therapy of Malignant Pleural Mesothelioma

Efficacy and tumour selectivity of photodynamic therapy with two clinically approved sensitizers (mTHPC, verteporfin) were assessed for focal intracavitary photodynamic therapy (PDT) in rodents with malignant pleural mesothelioma (MPM) at recommended drug-light conditions and at escalating sensitizer dosages. MPM tumours were generated in 15 Fischer rats by subpleural mediastinal tumour cell injection followed after 5 days by intracavitary PDT with light delivery monitored by in situ dosimetry. Animals were intravenously sensitized either with mTHPC (0.1 mg/kg, n = 3; 0.2 mg/kg, n = 3) followed after 4 days by illumination with 20 J/cm(2) at 652 nm, or with verteporfin (0.6 mg/kg, n = 3; 1.2 mg/kg, n = 3) followed after 20 min by illumination with 100 J/cm(2) at 689 nm. Three untreated tumour-bearing animals served as controls. Histological evaluation of the treated tumour and of adjacent normal organs was performed 10 days after tumour implantation. The extent of PDT-induced tumour necrosis was compared to the non-necrosed area and expressed in percentage. A locally invasive growing MPM tumour (3.1 +/- 1 mm diameter) without spontaneous necrosis diameter was found in all animals. For both sensitizers, focal intracavitary PDT was well tolerated at drug-light conditions recommended for clinical applications. Mediastinal organs were spared for both sensitizers but verteporfin resulted in a higher extent of tumour necrosis (80%) than mTHPC (50%). Drug dose escalation revealed a higher extent of PDT-related tumour necrosis for both sensitizers (mTHPC 55%, verteporfin 88%), however, verteporfin-PDT was associated with a higher toxicity than mTHPC-PDT.

Performance of a contact textile-based light diffuser for photodynamic therapy

BACKGROUND

Medical textiles offer a unique contact opportunity that could provide value-added comfort, reliability, and safety for light or laser-based applications. We investigated a luminous textile diffuser for use in photodynamic therapy.

METHODS

Textile diffusers are produced by an embroidery process. Plastic optical fibers are bent and sewn into textile to release light by macrobending. A reflective backing is incorporated to improve surface homogeneity, intensity, and safety. Clonogenic assay (MCF-7 cells) and trypan blue exclusion (NuTu19 cells) tests were performed in vitro using 0.1μg/ml m-THPC with three textile diffusers and a standard front lens diffuser. Heating effects were studied in solution and on human skin. PDT application in vivo was performed with the textile diffuser on equine sarcoids (three animals, 50mW/cm(2), 10-20J) and eight research animals. Lastly, computer simulations were performed to see how the textile diffuser might work on a curved object.

RESULTS

At low fluency rate, there is a trend for the textile diffuser to have lower survival rates than the front lens diffuser for both cell lines. The textile diffuser was observed to retain more heat over a long period (>1min). All animals tolerated the treatments well and showed similar initial reactions. The simulations showed a likely focusing effect in a curved geometry.

CONCLUSIONS

The initial feasibility and application using a textile-based optical diffuser has been demonstrated. Possibilities that provide additional practical advantages of the textile diffuser are discussed.

The future of photodynamic therapy in oncology

The medicinal properties of light-based therapies have been appreciated for millennia. Yet, only in this century have we witnessed the birth of photodynamic therapy (PDT), which over the last few decades has emerged to prominence based on its promising results and clinical simplicity. The fundamental and distinguishing characteristics of PDT are based on the interaction of a photosensitizing agent, which, when activated by light, transfers its energy into an oxygen-dependent reaction. Clinically, this photodynamic reaction is cytotoxic and vasculotoxic. While the current age of PDT is based on oncological therapy, the future of PDT will probably show a significant expansion to non-oncological indications. This harks back to much of the original work from a century ago. Therefore, this paper will attempt to predict the future of PDT, based in part on a review of its origin.

Experimental photodynamic therapy for malignant pleural mesothelioma with pegylated mTHPC

BACKGROUND AND OBJECTIVES

Experimental assessment of photodynamic therapy (PDT) for malignant pleural mesothelioma using a polyethylene glycol conjugate of meta-tetrahydroxyphenylchlorin (PEG-mTHPC).

STUDY DESIGN/MATERIALS AND METHODS

(a) PDT was tested on H-meso-1 xenografts (652 nm laser light; fluence 10 J/cm(2); 0.93, 9.3, or 27.8 mg/kg of PEG-mTHPC; drug-light intervals 3-8 days). (b) Intraoperative PDT with similar treatment conditions was performed in the chest cavity of minipigs (n = 18) following extrapleural pneumonectomy (EPP) using an optical integrating balloon device combined with in situ light dosimetry.

RESULTS

(a) PDT using PEG-mTHPC resulted in larger extent of tumor necrosis than in untreated tumors (P < or = 0.01) without causing damage to normal tissue. (b) Intraoperative PDT following EPP was well tolerated in 17 of 18 animals. Mean fluence and fluence rates measured at four sites of the chest cavity ranged from 10.2 +/- 0.2 to 13.2 +/- 2.3 J/cm(2) and 5.5 +/- 1.2 to 7.9 +/- 1.7 mW/cm(2) (mean +/- SD). Histology 3 months after light delivery revealed no PDT related tissue injury in all but one animal.

CONCLUSIONS

PEG-mTHPC mediated PDT showed selective destruction of mesothelioma xenografts without causing damage to intrathoracic organs in pigs at similar treatment conditions. The light delivery system afforded regular light distribution to different parts of the chest cavity.

Menorrhagia: an update

Menorrhagia is defined as a 'complaint of heavy cyclical menstrual bleeding occurring over several consecutive cycles'. Objectively it is a total menstrual blood loss equal to or greater than 80 ml per menstruation. It is estimated that approximately 30% of women complain of menorrhagia. Excessive bleeding is the main presenting complaint in women referred to gynecologists and it accounts for two-thirds of all hysterectomies, and most of endoscopic endometrial destructive surgery. Thus, menorrhagia is an important healthcare problem. Its etiology, investigation, medical and surgical management are described. In approximately 50% of cases of menorrhagia no pathology is found at hysterectomy. Abnormal levels of prostaglandins or the fibrinolytic system in the endometrium have been implicated. Effective medical treatments suitable for long-term use include intrauterine progestogens, antifibrinolytic agents (tranexamic acid) and nonsteroidal anti-inflammatory agents (mefenamic acid). Over the past decade there has been increasing use of endometrial destructive techniques as an alternative to hysterectomy. Their further refinement and the advent of fibroid embolization has increased the options available to women.

Clinical potential of photodynamic therapy in cardiovascular disorders

Atherosclerosis and intimal hyperplasia remain obstacles for surgeons to overcome following vascular reconstructions. Even with all of the technical improvements that have occurred in the past several decades, long term patency following intervention is hindered by these inherent adverse developments. Today, the use of light is seen as a potential treatment modality in vascular surgery. Photodynamic therapy (PDT) has been used in the treatment of cancer, and because of its continued success in vascular experimental models it is now being tested in clinical trials for vascular diseases. PDT offers the surgeon many advantages, and it may have unlimited uses in the clinical setting. Is PDT the ultimate treatment modality for the cardiovascular surgeon and will it help to overcome the inherent failures associated with vascular reconstructions? It may be too early to answer these questions, but with the current successes demonstrated by PDT, there is a need for further testing in clinical trials. In the near future, PDT may be used clinically as a treatment modality to inhibit restenosis and intimal hyperplasia following surgical intervention.