In vitro light distributions from intracranial PDT balloons

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.

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.

Interstitial PDT using diffuser fiber-investigation in phantom and in vivo models

Photodynamic therapy (PDT) has been used for local treatment of several types of tumors. Light penetration of biological tissue is one limiting factor in PDT, decreasing the success rates of the treatment of invasive and solid tumors. In those cases, a possible solution is to use interstitial PDT, in which both diffuser optical fibers are inserted into the tumor. The uniformity of the diffuser emission plays a crucial role in planning the delivery of the appropriate light fluence and in ensuring treatment success. In this study, we characterized a diffuser optical fiber concerning its homogeneity. We showed that the diffuser emission can be inhomogeneous and that the necrosis generated by interstitial PDT using such a diffuser for illumination is asymmetrical in volume as a result. This observation has relevant consequences in achieving success in PDT and phototherapies in general, as the delivered light fluence depends on adequate previous knowledge of the irradiation profile.

Photodynamic applications in brain tumors: a comprehensive review of the literature

INTRODUCTION

GBM is the comment glioma. GBM-outcome had not changed much over two decades despite leaps in medical technology. Fewer than 25% survive 2 years. There is no jacket that fits all GBMs. This paper reviews the evidence for PDT in GBMs.

RATIONALE

Maximum safe resection is supported by level-II evidence. PDT-technology (PDTT) provides means to maximize safe resection. PDTT paints GBM red in contrast to brain because of selective uptake and retention of photosensitizers. Exposure to specific light wave produces cytotoxic singlet oxygen. PDT-APPLICATIONS: (1) Fluorescence image guided biopsy to sample high grade components of what looks like low grade glioma on MRI, 89% sensitive. (2) Fluorescence image guided surgery for maximum safe surgical resection is >84% sensitive, achieves complete resection in >65% and prolongs tumor free survival (1 observational and 2 RCT, p < 0.001). (3) Photodynamic treatment supported by several observational studies with combined total of >1000 patients and 3 RCT used PDT in GBMs. PDT was highly selective, safe, significantly improved good quality survival, and delayed tumor relapse (p < 0.001).

SAFETY

PDT had a very high safety track record, thromboembolism 2%, brain-oedema 1.3%, and skin photosensitivity complications 1-3%.

CONCLUSION

PDT in GBMs is safe, selective, and sensitive and leads to significant prolongation of good quality survival, delay in tumor relapse and significant reduction of further interventions. It would be impractical, impossible and probably unethical to randomize patients between PDT and placebo, in the same way it would be unethical to carry out a RCT to prove that the parachute saves lives.