Use of photosensitive, antibody directed liposomes to destroy target populations of cells in bone marrow: a potential purging method for autologous bone marrow transplantation

Advances in Liposome-Encapsulated Phthalocyanines for Photodynamic Therapy

This updated review aims to describe the current status in the development of liposome-based systems for the targeted delivery of phthalocyanines for photodynamic therapy (PDT). Although a number of other drug delivery systems (DDS) can be found in the literature and have been studied for phthalocyanines or similar photosensitizers (PSs), liposomes are by far the closest to clinical practice. PDT itself finds application not only in the selective destruction of tumour tissues or the treatment of microbial infections, but above all in aesthetic medicine. From the point of view of administration, some PSs can advantageously be delivered through the skin, but for phthalocyanines, systemic administration is more suitable. However, systemic administration places higher demands on advanced DDS, active tissue targeting and reduction of side effects. This review focuses on the already described liposomal DDS for phthalocyanines, but also describes examples of DDS used for structurally related PSs, which can be assumed to be applicable to phthalocyanines as well.

Impacting Pancreatic Cancer Therapy in Heterotypic in Vitro Organoids and in Vivo Tumors with Specificity-Tuned, NIR-Activable Photoimmunonanoconjugates: Towards Conquering Desmoplasia?

Despite untiring efforts to develop therapies for pancreatic ductal adenocarcinoma (PDAC), survival statistics remain dismal, necessitating distinct approaches. Photodynamic priming (PDP), which improves drug delivery and combination regimens, as well as tumor photodestruction are key attributes of photodynamic therapy (PDT), making it a distinctive clinical option for PDAC. Localized, high-payload nanomedicine-assisted delivery of photosensitizers (PSs), with molecular specificity and controlled photoactivation, thus becomes critical in order to reduce collateral toxicity during more expansive photodynamic activation procedures with curative intent. As such, targeted photoactivable lipid-based nanomedicines are an ideal candidate but have failed to provide greater than two-fold cancer cell selectivity, if at all, due to their extensive multivariant physical, optical, and chemical complexity. Here, we report (1) a systematic multivariant tuning approach to engineer (Cet, anti-EGFR mAb) photoimmunonanoconjugates (PINs), and (2) stroma-rich heterotypic PDAC in vitro and in vivo models incorporating patient-derived pancreatic cancer-associated fibroblasts (PCAFs) that recapitulate the desmoplasia observed in the clinic. These offer a comprehensive, disease-specific framework for the development of Cet-PINs. Specificity-tuning of the PINs, in terms of PS lipid anchoring, electrostatic modulation, Cet orientation, and Cet surface densities, achieved ∼16-fold binding specificities and rapid penetration of the heterotypic organoids within 1 h, thereby providing a ∼16-fold enhancement in molecular targeted NIR photodestruction. As a demonstration of their inherent amenability for multifunctionality, encapsulation of high payloads of gemcitabine hydrochloride, 5-fluorouracil, and oxaliplatin within the Cet-PINs further improved their antitumor efficacy in the heterotypic organoids. In heterotypic desmoplastic tumors, the Cet-PINs efficiently penetrated up to 470 μm away from blood vessels, and photodynamic activation resulted in substantial tumor necrosis, which was not elicited in T47D tumors (low EGFR) or when using untargeted constructs in both tumor types. Photodynamic activation of the Cet-PINs in the heterotypic desmoplastic tumors resulted in collagen photomodulation, with a 1.5-fold reduction in collagen density, suggesting that PDP may also hold potential for conquering desmoplasia. The in vivo safety profile of photodynamic activation of the Cet-PINs was also substantially improved, as compared to the untargeted constructs. While treatment using the Cet-PINs did not cause any detriment to the mice's health or to healthy proximal tissue, photodynamic activation of untargeted constructs induced severe acute cachexia and weight loss in all treated mice, with substantial peripheral skin necrosis, muscle necrosis, and bowel perforation. This study is the first report demonstrating the true value of molecular targeting for NIR-activable PINs. These constructs integrate high payload delivery, efficient photodestruction, molecular precision, and collagen photomodulation in desmoplastic PDAC tumors in a single treatment using a single construct. Such combined PIN platforms and heterocellular models open up an array of further multiplexed combination therapies to synergistically control desmoplastic tumor progression and extend PDAC patient survival.

Porphyrinoid biohybrid materials as an emerging toolbox for biomedical light management

The present article reviews the most important developing strategies in light-induced nanomedicine, based on the combination of porphyrinoid photosensitizers with a wide variety of biomolecules and biomolecular assemblies.

Bispecific single-chain antibodies as effective tools for eliminating epithelial cancer cells from human stem cell preparations by redirected cell cytotoxicity

High-dose chemotherapy (HDC) with autologous bone marrow or peripheral stem cell transplantation is discussed as one option to treat the extensive stage of a variety of tumors. Effective methods to eliminate contaminating tumor cells from human bone marrow or stem cell grafts may improve the outcome of the patients. We investigated 3 recombinant bispecific single-chain antibodies (bscAbs) directed against 17-1A (EpCAM), c-erbB-2 (HER-2/neu) and LeY on the one and CD3 on the other binding site for their ability to induce lysis of epithelial tumor cells by retargeting autochthonous T lymphocytes present in bone marrow mononuclear cells (BMMC) and in peripheral stem cell mononuclear cells (PSMC). The bscAbs showed remarkable specific lysis of different epithelial tumor cell lines with BMMCs as well as with PSMCs as effector cells. Investigation of the alpha 17-1A-alpha CD3 bscAb revealed a significant correlation between the percentage of CD3(+) cells present in the BMMCs and the rate of lysis as well as the absence of detrimental effects on the viability of hematopoietic progenitor cells as determined by colony-forming unit assays (CFUs). Our results indicate that recombinant bispecific single-chain antibodies could be new tools for purging of human bone marrow and peripheral stem cell grafts from contaminating epithelial cancer cells for patients receiving autologous stem cell transplantation after HDC.

The use of phage display for the development of tumour targeting agents

One way to improve the selectivity of therapeutic molecules in clinical oncology would be to target them on the tumour site, thereby sparing normal tissues. The development of targeted therapeutic methodologies relies in most cases on the availability of binding molecules specific for tumour-associated markers. The display of repertoires of polypeptides on the surface of filamentous phage, together with the efficient selection-amplification of the desired binding specificities using affinity capture, represents an efficient route towards the isolation of specific peptides and proteins that could act as vehicles for tumour targeting applications. Most investigations in this area of research have so far been performed with phage derived recombinant antibodies, which have been shown to selectively target tumour-associated markers both in preclinical animal models and in the clinic. However, future developments with other classes of polypeptides (small constrained peptides, small globular proteins) promise to be important for the selective delivery of therapeutic agents to the tumour site.

Immunoliposomes for the targeted delivery of antitumor drugs

This review presents an overview of the field of immunoliposome-mediated targeting of anticancer agents. First, problems that are encountered when immunoliposomes are used for systemic anticancer drug delivery and potential solutions are discussed. Second, an update is given of the in vivo results obtained with immunoliposomes in tumor models. Finally, new developments on the utilization of immunoliposomes for the treatment of cancer are highlighted.

Effect of hypothermia on the merocyanine 540-mediated purging of hematopoietic cells

Merocyanine 540 (MC540)-mediated photodynamic therapy (PDT) inactivates experimental leukemia, lymphoma, and neuroblastoma cells by a singlet oxygen-mediated mechanism but is relatively well tolerated by normal pluripotent hematopoietic stem cells and granulocyte/macrophage progenitors (CFU-GM). MC540 is currently undergoing phase I clinical testing for the extracorporeal purging of autologous bone marrow and peripheral blood stem cells. We report here that performing MC540-mediated PDT at 4.7 degrees C (hypothermia) instead of at ambient temperature enhanced the photoinactivation of L1210 cells and CFU-GM but left the photoinactivation of K562 cells unchanged. Hypothermia reduced dye binding in K562 but not in L1210 cells, whereas the photogeneration of lipid hydroperoxides (LOOH) was affected in neither cell line. Post-PDT incubation at 4 degrees C delayed the decay of LOOH and enhanced the photoinactivation of CFU-GM as well as L1210 and K562 cells. Taken together, these results suggest that hypothermia interfered with the repair of potentially lethal photodynamic damage. They stress the importance of temperature control during and immediately after the photochemical purging of autologous bone marrow and peripheral blood stem cells.

A comparison of direct and liposomal antibody conjugates of sulfonated aluminum phthalocyanines for selective photoimmunotherapy of human bladder carcinoma

There is a need to improve the selectivity of photodynamic therapy and for better targeting of tumor cells within specific tumor compartments. Selective in vitro phototoxicity of a human bladder carcinoma cell line 647V has been achieved by targeting sulfonated aluminum phthalocyanines (AlSPc) with monoclonal antibodies. Aluminum tetra-3 sulfonyl chloride phthalocyanine (PC) or rhodamine sulfonyl chloride were directly coupled to antibodies by a sulfonamide linkage and AlSPc or carboxyfluorescein were encapsulated in liposomes of the small unilamellar vesicle type (SUV) bearing antibody. Antibody E7 (IgM subclass), which recognized an antigenic determinant expressed on 647V but was absent on T24 a control human bladder carcinoma cell line, and a control IgM antibody were used. The effects of the two types of conjugate were compared. Immunofluorescence studies on living cells demonstrated specific cell surface localization of conjugates at 4 degrees C and internalization at 37 degrees C. Phototoxicity was measured by 3-(4,5-dimethylthiazol-2-5-diphenyltetrazolium) bromide assay after exposing AlSPc-sensitized cells to red light. Significant AlSPc dose-dependent phototoxicity of the order 4 degrees C < 4 degrees C plus 37 degrees C < 37 degrees C was observed with E7-SUV and E7-PC in the range 1-8 microM AlSPc. At equimolar AlSPc doses absolute toxicity was similar for the two conjugate types, but at equimolar antibody doses, the liposomal conjugate was more effective by up to 13-fold. Addition of urine during illumination decreased toxicity, which was attributed to the presence of protective elements. The results suggest that photosensitizers such as AlSPc could be used for antibody-directed therapy and in particular for selectively damaging tumor cells of the epithelial cell compartment in bladder carcinoma by intrabladder administration. The therapeutic ratio, which takes into account both specific and nonspecific toxicity, was greater for the liposome conjugate than for the direct conjugate indicating their greater suitability for in vivo instillation.

Hepatic perfusion changes in patients with liver metastases: comparison with those patients with cirrhosis

Previous studies using dynamic scintigraphy have shown that the measurement of changes in hepatic perfusion may be exploited to detect liver metastases. Similar hepatic haemodynamic changes also occur in cirrhosis, however, thereby reducing the diagnostic power of the technique. The ability of duplex colour Doppler sonography (DCDS) to differentiate between the changes in liver perfusion in patients with cirrhosis and those with hepatic metastases was assessed. Hepatic arterial and portal venous blood flows were measured in 30 control subjects, 20 patients with cirrhosis, and 55 patients with overt liver metastases. The Doppler perfusion index (DPI) (the rate of hepatic arterial to total liver blood flow) and the congestive index (ratio of the cross sectional area of the vessel to time averaged velocity of blood flow in the vessel) of the hepatic artery (HCI) and portal vein (PCI) were calculated. The hepatic arterial blood flow of the cirrhotic and metastatic groups was significantly raised compared with that of controls, and the portal venous blood flow of the former groups were reduced (p < 0.0001). The DPIs of the cirrhotic and metastatic groups were therefore significantly raised compared with those of controls (p < 0.0001). No significant difference was noted in HCI values between the three groups. The PCI values of the cirrhotic group, however, were significantly raised compared with those of controls and patients with metastases (p < 0.0001). The data suggest that DCDS measurement of PCI may be of value in differentiating between the hepatic perfusion changes caused by cirrhosis and those resulting from hepatic metastases, thereby increasing the diagnostic power of this technique.