Photodynamic therapy for intracranial neoplasms: investigations of photosensitizer uptake and distribution using indium-111 Photofrin-II single photon emission computed tomography scans in humans with intracranial neoplasms

Recent Advances in Photosensitizers as Multifunctional Theranostic Agents for Imaging-Guided Photodynamic Therapy of Cancer

In recent years tremendous effort has been invested in the field of cancer diagnosis and treatment with an overall goal of improving cancer management, therapeutic outcome, patient survival, and quality of life. Photodynamic Therapy (PDT), which works on the principle of light-induced activation of photosensitizers (PS) leading to Reactive Oxygen Species (ROS) mediated cancer cell killing has received increased attention as a promising alternative to overcome several limitations of conventional cancer therapies. Compared to conventional therapies, PDT offers the advantages of selectivity, minimal invasiveness, localized treatment, and spatio-temporal control which minimizes the overall therapeutic side effects and can be repeated as needed without interfering with other treatments and inducing treatment resistance. Overall PDT efficacy requires proper planning of various parameters like localization and concentration of PS at the tumor site, light dose, oxygen concentration and heterogeneity of the tumor microenvironment, which can be achieved with advanced imaging techniques. Consequently, there has been tremendous interest in the rationale design of PS formulations to exploit their theranostic potential to unleash the imperative contribution of medical imaging in the context of successful PDT outcomes. Further, recent advances in PS formulations as activatable phototheranostic agents have shown promising potential for finely controlled imaging-guided PDT due to their propensity to specifically turning on diagnostic signals simultaneously with photodynamic effects in response to the tumor-specific stimuli. In this review, we have summarized the recent progress in the development of PS-based multifunctional theranostic agents for biomedical applications in multimodal imaging combined with PDT. We also present the role of different imaging modalities; magnetic resonance, optical, nuclear, acoustic, and photoacoustic in improving the pre-and post-PDT effects. We anticipate that the information presented in this review will encourage future development and design of PSs for improved image-guided PDT for cancer treatment.

Boron Neutron Capture Therapy and Photodynamic Therapy for High-Grade Meningiomas

Meningiomas are the most common type of intracranial brain tumors in adults. The majority of meningiomas are benign with a low risk of recurrence after resection. However, meningiomas defined as grades II or III, according to the 2016 World Health Organization (WHO) classification, termed high-grade meningiomas, frequently recur, even after gross total resection with or without adjuvant radiotherapy. Boron neutron capture therapy (BNCT) and photodynamic therapy (PDT) are novel treatment modalities for malignant brain tumors, represented by glioblastomas. Although BNCT is based on a nuclear reaction and PDT uses a photochemical reaction, both of these therapies result in cellular damage to only the tumor cells. The aim of this literature review is to investigate the possibility and efficacy of BNCT and PDT as novel treatment modalities for high-grade meningiomas. The present review was conducted by searching PubMed and Scopus databases. The search was conducted in December 2019. Early clinical studies of BNCT have demonstrated activity for high-grade meningiomas, and a phase II clinical trial is in progress in Japan. As for PDT, studies have investigated the effect of PDT in malignant meningioma cell lines to establish PDT as a treatment for malignant meningiomas. Further laboratory research combined with proper controlled trials investigating the effects of these therapies is warranted.

Photodynamic Therapy for the Treatment of Glioblastoma

Glioblastoma is the most common form of adult brain cancer and remains one of the deadliest of human cancers. The current standard-of-care involves maximal tumor resection followed by treatment with concurrent radiation therapy and the chemotherapy temozolomide. Recurrence after this therapy is nearly universal within 2 years of diagnosis. Notably, >80% of recurrence is found in the region adjacent to the resection cavity. The need for improved local control in this region, thus remains unmet. The FDA approval of 5-aminolevulinic acid (5-ALA) for fluorescence guided glioblastoma resection renewed interests in leveraging this agent as a means to administer photodynamic therapy (PDT). Here we review the general principles of PDT as well as the available literature on PDT as a glioblastoma therapeutic platform.

[Chordoma]

PURPOSES

To review in the literature, all the epidemiological, clinical, radiological, histological and therapeutic data regarding chordomas as well as various notochordal entities: ecchordosis physaliphora, intradural and intraparenchymatous chordomas, benign notochordal cell tumors, parachordomas and extra-axial chordomas. To identify different types of chordomas, including familial forms, associations with tuberous sclerosis, Ollier's disease and Maffucci's syndrome, forms with metastasis and seeding. To assess the recent data regarding molecular biology and progress in targeted therapy. To compare the different types of radiotherapy, especially protontherapy and their therapeutic effects. To review the largest series of chordomas in their different localizations (skull base, sacrum and mobile spine) from the literature.

MATERIALS

The series of 136 chordomas treated and followed up over 20 years (1972-2012) in the department of neurosurgery at Lariboisière hospital is reviewed. It includes: 58 chordomas of the skull base, 47 of the craniocervical junction, 23 of the cervical spine and 8 from the lombosacral region. Similarly, 31 chordomas in children (less than 18 years of age), observed in the departments of neurosurgery of les Enfants-Malades and Lariboisière hospitals, are presented. They were observed between 1976 and 2010 and were located intracranially (n=22 including 13 with cervical extension), 4 at the craniocervical junction level and 5 in the cervical spine.

METHODS

In the entire Lariboisière series and in the different groups of localization, different parameters were analyzed: the delay of diagnosis, of follow-up, of occurrence of metastasis, recurrence and death, the number of primary patients and patients referred to us after progression or recurrence and the number of deaths, recurrences and metastases. The influence of the quality of resection (total, subtotal and partial) on the prognosis is also presented. Kaplan-Meier actuarial curves of overall survival and disease free survival were performed in the entire series, including the different groups of localization based on the following 4 parameters: age, primary and secondary patients, quality of resection and protontherapy. In the pediatric series, a similar analysis was carried-out but was limited by the small number of patients in the subgroups.

RESULTS

In the Lariboisière series, the mean delay of diagnosis is 10 months and the mean follow-up is 80 months in each group. The delay before recurrence, metastasis and death is always better for the skull base chordomas and worse for those of the craniocervical junction, which have similar results to those of the cervical spine. Similar figures were observed as regards the number of deaths, metastases and recurrences. Quality of resection is the major factor of prognosis with 20.5 % of deaths and 28 % of recurrences after total resection as compared to 52.5 % and 47.5 % after subtotal resection. This is still more obvious in the group of skull base chordomas. Adding protontherapy to a total resection can still improve the results but there is no change after subtotal resection. The actuarial curve of overall survival shows a clear cut in the slope with some chordomas having a fast evolution towards recurrence and death in less than 4 years and others having a long survival of sometimes more than 20 years. Also, age has no influence on the prognosis. In primary patients, disease free survival is better than in secondary patients but not in overall survival. Protontherapy only improves the overall survival in the entire series and in the skull base group. Total resection improves both the overall and disease free survival in each group. Finally, the adjunct of protontherapy after total resection is clearly demonstrated. In the pediatric series, the median follow-up is 5.7 years. Overall survival and disease free survival are respectively 63 % and 54.3 %. Factors of prognosis are the histological type (atypical forms), localization (worse for the cervical spine and better for the clivus) and again it will depend on the quality of resection.

CONCLUSIONS

Many different pathologies derived from the notochord can be observed: some are remnants, some may be precursors of chordomas and some have similar features but are probably not genuine chordomas. To-day, immuno-histological studies should permit to differentiate them from real chordomas. Improving knowledge of molecular biology raises hopes for complementary treatments but to date the quality of surgical resection is still the main factor of prognosis. Complementary protontherapy seems useful, especially in skull base chordomas, which have better overall results than those of the craniocervical junction and of the cervical spine. However, we are still lacking an intrinsic marker of evolution to differentiate the slow growing chordomas with an indolent evolution from aggressive types leading rapidly to recurrence and death on which more aggressive treatments should be applied.

Labelling and optimization of PHOTOFRIN® with 99mTc

PHOTOFRIN® was labelled with 99mTc using SnCl2·2H2O as reducing agent. Instant thin layer chromatography (ITLC-SG) in 0.05 M NaOH was used for evaluation of radiochemical purity. Labelling efficiency was dependent on various factors that include the ligand/reductant ratio, pH and time of incubation. Therefore, optimum conditions of labelling were also determined. The stability of 99mTc-PHOTOFRIN® in serum was checked by using fresh human serum. Tissue distribution of 99mTc-PHOTOFRIN® was evaluated in Sprague Dawley rats.

PHOTOFRIN® was labelled with an efficiency of >95% under optimum conditions, which were PHOTOFRIN®: 200 μg, pH: 3–4, SnCl2·2H2O: 15 μg and 30 min incubation at room temperature. The 99mTc-labelled PHOTOFRIN® remained stable in human serum for 24 h. Biodistribution study in rats revealed maximum concentration of the labelled compound in liver, lungs and spleen at 0.5 h, and significant activity was also seen in the bladder and urine, indicating the mode of urinary excretion of PHOTOFRIN®.

Compared to purpurinimides, the pyropheophorbide containing an iodobenzyl group showed enhanced PDT efficacy and tumor imaging (124I-PET) ability

Two positional isomers of purpurinimide, 3-[1'-(3-iodobenzyloxyethyl)] purpurin-18-N-hexylimide methyl ester 4, in which the iodobenzyl group is present at the top half of the molecule (position-3), and a 3-(1'-hexyloxyethy)purpurin-18-N-(3-iodo-benzylimide)] methyl ester 5, where the iodobenzyl group is introduced at the bottom half (N-substitued cyclicimide) of the molecule, were derived from chlorophyll-a. The tumor uptake and phototherapeutic abilities of these isomers were compared with the pyropheophorbide analogue 1 (lead compound). These compounds were then converted into the corresponding 124I-labeled PET imaging agents with specific activity >1 Ci/micromol. Among the positional isomers 4 and 5, purpurinimide 5 showed enhanced imaging and therapeutic potential. However, the lead compound 1 derived from pyropheophorbide-a exhibited the best PET imaging and PDT efficacy. For investigating the overall lipophilicity of the molecule, the 3-O-hexyl ether group present at position-3 of purpurinimide 5 was replaced with a methyl ether substituent, and the resulting product 10 showed improved tumor uptake, but due to its significantly higher uptake in the liver, spleen, and other organs, a poor tumor contrast in whole-body tumor imaging was observed.

ALA and Photofrin fluorescence-guided resection and repetitive PDT in glioblastoma multiforme: a single centre Phase III randomised controlled trial

Glioblastoma multiforme (GBM) carries dismal prognosis and cannot be eradicated surgically because of its wide brain invasion. The objective of this prospective randomised controlled trial was to evaluate ALA and Photofrin fluorescence-guided resection (FGR) and repetitive photodynamic therapy (PDT) in GBM. We recruited 27 patients; 13 were in the study group and 14 were in the control group. The mean survival of the study group was 52.8 weeks compared to 24.6 weeks in the control group (p<0.01). The study group gained on average 20 points on the Karnofsky performance score (p<0.05). There were no differences in complications or hospital stay between the two groups. The mean time to tumour progression was 8.6 months in the study group compared to 4.8 months in the control group (p<0.05). Therefore, ALA and Photofrin fluorescence-guided resection and repetitive PDT offered a worthwhile survival advantage without added risk to patients with GBM. A multicentre randomized controlled trial is warranted to confirm these results.

Preparation and biological evaluation of the new chlorin photosensitizer T3,4BCPC for detection and treatment of tumors

The new water-soluble photosensitizer 5,10,15,20-tetrakis[3,4-bis(carboxymethyleneoxy)phenyl]chlorin (T3,4BCPC) has been prepared, characterized and labeled with 99mTc radionuclide. The radiotracer was evaluated for tissue distribution in Wistar rats. Accumulation of administrated activities in the liver, kidney, bladder and large intestine at 4 h post-injection indicated that the labeled ligand was largely eliminated through the renal and partly through the hepatobiliary system. In vivo biodistribution studies of the labeled compound were carried out in rodent and murine tumor models in comparison with other tumor-seeking radiopharmaceuticals such as 99mTc(V)-dimercaptosuccinic acid (DMSA), 201thallous chloride (TlCl) and 99mTc-citrate using a gamma camera computer system. In N-nitrosomethylurea (NMU)-induced rat mammary tumors, the labeled ligand showed a five-fold tumor to muscle (T/M) ratio compared to 99mTc(V)-DMSA (3-fold) and 201TlCl (3-fold). In the case of C(3)H/J virus-induced spontaneous mammary tumors, the differences were not marked. However, in the transplanted rat C(6)-glioma, the T/M ratio of the labeled compound was appreciably higher (four-fold) than that noted with 99mTc(V)-DMSA (two-fold), 201TlCl (three-fold) and 99mTc-citrate (more than three-fold). These findings suggest that the radiolabeled T3,4BCPC may have potential for the detection of cancer. In order to ascertain the efficacy of the compound for photodynamic therapy applications, a preclinical PDT study was carried out in fibrosarcoma-bearing mice after injecting 5.0 mg/kg body weight of the T3,4BCPC. A laser dose of 20 mW for 60 s resulted in 80% destruction of tumors. These data suggest that this molecule could be useful for PDT of cancer. The labeled agent could also be useful in monitoring the progression/regression of tumors before, during, and after chemotherapy, radiation therapy or PDT.

Photodynamic therapy for malignant newly diagnosed supratentorial gliomas

We report the use of photodynamic therapy (PDT) in the treatment of 20 patients with newly diagnosed malignant supratentorial gliomas. There were 10 males and 10 females; their mean age was 56 years and the mean Karnofsky score was 75. Eleven patients had glioblastoma multiforme (GBM) and 9 had malignant astrocytoma (MA). Intravenous porphyrin photosensitizer was administered 12-36 h prior to surgery and photoillumination. At operation all patients had the tumor subtotally resected followed by intraoperative cavitary photoillumination. Interstitial photoillumination using fibers with 2-cm diffusing tips supplemented the cavitary illumination in 3 patients. The total light energy delivered ranged from 570 to 4050 J (median = 1260 J). The energy density ranged from 15 to 110 J/cm2 (median = 32 J/cm2). All but two had postoperative radiation therapy (5000 cGy in 5 weeks). No untoward effects of radiation in conjunction with PDT were identified. There was 1 postoperative death and 1 patient had a persistent increase in postoperative neurological deficit. The median survival of these 20 patients with newly diagnosed malignant gliomas was 44 weeks with a 1- and 2-year survival of 40 and 15%, respectively. The median survival of these patients with newly diagnosed GBM was 37 weeks with a 1- and 2-year survival of 35 and 0%, respectively, and the median survival for MA was 48 weeks with a 1- and 2-year survival of 44 and 33%, respectively. Six patients with a Karnofsky score of > 70 who received a light dose of > 1260 J (mean energy density = 62 +/- 20 SEM J/cm2) had a median survival of 92 weeks with a 1- and 2-year survival of 83 and 33% respectively. Patients with malignant astrocytic tumors (GBM and MA) have a very poor prognosis. Nevertheless PDT is safe in newly diagnosed patients with supratentorial malignant gliomas who undergo postoperative radiation and appears to prolong survival in selected patients when an adequate light dose is used. Further improvement in survival may be expected with higher light doses.

Damage threshold of normal rat brain in photodynamic therapy

Normal brain tissue response to photodynamic therapy (PDT) must be quantified in order to implement PDT as a treatment of brain neoplasm. We therefore calculated the threshold for PDT-induced tissue necrosis in normal brain using Photofrin (porfimer sodium, Quadralogic Technologies Inc., Vancouver, BC) as the photosensitizer. The absolute light fluence-rate distribution for superficial irradiation and effective attenuation depth were measured in vivo using an invasive optical probe. Photosensitizer uptake in cerebral cortex was measured with chemical extraction and fluorometric analysis. Photodynamic therapy-induced lesion depths at various drug dose levels were measured as a biological end point. The PDT threshold for normal brain necrosis was calculated as in the magnitude of 10(16) photons/cm3. Thus normal rat brain is extremely vulnerable to PDT damage. This suggests that extra precautions must be exercised when PDT is used in brain.

The sensitivity of normal brain and intracranially implanted VX2 tumour to interstitial photodynamic therapy

The applicability and limitations of a photodynamic threshold model, used to describe quantitatively the in vivo response of tissues to photodynamic therapy, are currently being investigated in a variety of normal and malignant tumour tissues. The model states that tissue necrosis occurs when the number of photons absorbed by the photosensitiser per unit tissue volume exceeds a threshold. New Zealand White rabbits were sensitised with porphyrin-based photosensitisers. Normal brain or intracranially implanted VX2 tumours were illuminated via an optical fibre placed into the tissue at craniotomy. The light fluence distribution in the tissue was measured by multiple interstitial optical fibre detectors. The tissue concentration of the photosensitiser was determined post mortem by absorption spectroscopy. The derived photodynamic threshold values for normal brain are significantly lower than for VX2 tumour for all photosensitisers examined. Neuronal damage is evident beyond the zone of frank necrosis. For Photofrin the threshold decreases with time delay between photosensitiser administration and light treatment. No significant difference in threshold is found between Photofrin and haematoporphyrin derivative. The threshold in normal brain (grey matter) is lowest for sensitisation by 5 delta-aminolaevulinic acid. The results confirm the very high sensitivity of normal brain to porphyrin photodynamic therapy and show the importance of in situ light fluence monitoring during photodynamic irradiation.

Photodynamic therapy for recurrent supratentorial gliomas

We have used photodynamic therapy (PDT) in the treatment of 56 patients with recurrent supratentorial gliomas who had failed radiation therapy and who were candidates for palliative reoperation. There were 34 males and 22 females; their mean age was 41 years and the mean Karnofsky score was 79. Thirty-two patients had glioblastoma multiforme (GBM), 14 had malignant astrocytoma (MA), 6 had malignant mixed glioma (MM), and 4 had ependymoma (EP). Porphyrin photosensitizer was administered intravenously (i.v.) 12-36 hours prior to photoillumination. All patients had the recurrent tumor subtotally resected or cyst drained at surgery followed by intraoperative cavitary photoillumination. In 15 cases interstitial photoillumination using fibers with 2 cm diffusing tips supplemented the cavitary illumination. The total light energy delivered ranged from 440 to 4,500 Joules (J) (median = 1,800 J). The energy administered ranged from 120 to 150 J per fiber and the linear energy density ranged from 65 to 450 J/cm. The energy density ranged from 8 to 110 J/cm2 (median = 38 J/cm2). There were two postoperative deaths and three patients were left with a persistent increase in their postoperative neurological deficit. The post-PDT median survival of patients with recurrent GBM was 30 weeks with a 1- and 2-year actuarial survival of 18% and 0%, respectively. The median survival of patients with recurrent GBM from first diagnosis was 118 weeks with a 1- and 2-year actuarial survival of 82% and 57%, respectively. The post-PDT median survival of patients with recurrent MA was 44 weeks with a 1- and 2-year actuarial survival of 43% and 36%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Enhanced optical imaging of rat gliomas and tumor margins

Current intraoperative methods used to maximize the extent of tumor removal are limited to intraoperative biopsies, ultrasound, and stereotactic volumetric resections. A new technique involving the optical imaging of an intravenously injected dye has the potential to localize tumors and their margins with a high degree of accuracy. In a rat glioma model, enhanced optical imaging was performed and indocyanine green was used as the contrast-enhancing agent. In all 22 animals, the peak optical change in the tumor was greater than in the ipsilateral brain around the tumor and the contralateral normal hemisphere. The clearance of the dye was significantly delayed to a greater extent in the tumor than in the brain around the tumor and the normal brain. After attempts were made at complete microscopic resection, enhanced optical imaging of the tumor margins and the histological samples demonstrated a specificity of 93% and a sensitivity of 89.5%. Enhanced optical imaging was capable of outlining the tumor even when the imaging was done through the cranium. The optical imaging of rat gliomas with a contrast-enhancing dye is able to differentiate between normal brain and tumor tissue both at the cortical surface and at the tumor margins. The application of these studies in an intraoperative clinical setting may allow for the more accurate determination of tumor margins and may increase the extent of tumor removal.

Necrosis in a meningioma following systemic chemotherapy. Case report

Radiological and clinical evidence of acute necrosis in a meningioma following one cycle of chemotherapy with 5-fluorouracil, folinic acid, and levamisole was observed in a patient being treated for invasive rectal carcinoma. The possible mechanisms and implications of this occurrence are discussed.

Photodynamic therapy for intracranial neoplasms. Literature review and institutional experience

Primary malignant glial neoplasms of the central nervous system have a dismal 2-yr prognosis. An innovative approach to these formidable lesions is photodynamic therapy that employs a chemotherapeutic photosensitizing agent in combination with wavelength specific light to produce cytotoxic reactions capable of destroying neoplastic tissues. Animal and initial clinical studies of the application of photodynamic therapy to intracranial neoplasms have been promising. Parameters to optimize the efficacy of this treatment are under investigation. A review of the preclinical and clinical studies of photodynamic therapy for intracranial neoplasms is described.

Lasers in neurosurgery

Lasers have been used in neurosurgery for the past 25 years, undergoing modifications to suit the specific needs of this medical discipline. The present report reviews the current use of lasers in neurosurgical practice and examines the pros and cons of lasers in specific neurosurgical applications. In spite of their advantages, laser use is still not widespread in neurosurgery. One reason is the continued lack of complete control over real-time laser interactions with neural tissue. A greater acceptance and use of lasers by neurosurgeons will depend upon automated control over defined specific parameters for laser applications based upon the type of tissue, the desired effect on tissue, and application to the clinical situation without loss of precision and a lot of expense. This will require the integration of newer lasers, computers, robotics, stereotaxy, and concepts of minimally invasive surgery into the routine management of neurosurgical problems.

The role of photodynamic therapy in posterior fossa brain tumors. A preclinical study in a canine glioma model

Photodynamic therapy was studied in dogs with and without posterior fossa glioblastomas. This mode of therapy consisted of intravenous administration of Photofrin-II at doses ranging from 0.75 to 4 mg/kg 24 hours prior to laser light irradiation in the posterior fossa. Tissue levels of Photofrin-II were four times greater in the tumor than in the surrounding normal brain. Irradiation was performed using 1 hour of 500 mW laser light at a wavelength of 630 nm delivered through a fiberoptic catheter directly into the tumor bed via a burr hole. All animals receiving a high dose (4 or 2 mg/kg) of Photofrin-II developed serious brain-stem neurotoxicity resulting in death or significant residual neurological deficits. A lower dose (0.75 mg/kg) of Photofrin-II produced tumor kill without significant permanent brain-stem toxicity in either the control animals or the animals with cerebellar brain tumors receiving photodynamic therapy.

Photodynamic therapy for intracranial neoplasms: development of an image-based computer-assisted protocol for photodynamic therapy of intracranial neoplasms

Photodynamic therapy is being studied as an adjuvant therapy for malignant gliomas. Therapeutic efficacy is based on photosensitizer uptake kinetics and the ability to deliver adequate light doses to an appropriate treatment volume at the optimal time. Our laboratory has developed an image-based, computer-assisted treatment-planning protocol to study the treatment variables leading to optimizing photodynamic therapy for intracranial neoplasms. Fifteen patients with recurrent malignant glial tumors underwent 16 treatments in the developmental phase of the project in which light treatment volume was progressively expanded. Group I (n = 4) received postresection intracavitary photoillumination only, Group II (n = 3) received limited interstitial/intracavitary photoillumination, and Group III (n = 9) received multiple interstitial/intracavitary photoillumination. Between 3 and 18 interstitial fiber probes were placed through optically lucent tumor access catheters. Computed three-dimensional image-based treatment planning provided reproducible data-based tumor volumes, treatment volumes, and stereotactic accuracy for tumor volume resection and interstitial light fiber insertion. Initial observations include: 1) treatment failures occur outside of the effective light treatment volumes; 2) effective light volumes can be expanded safely with multiple stereotactically implanted interstitial light fibers; and 3) optimal treatment involves individualized tailoring of light dose volume and geometry. This protocol allows standardized scientific study of the variables affecting the application of photodynamic therapy for intracranial neoplasms.