ACE angiotensin converting enzyme BAL bronchoalveolar lavage CRT cardiac resynchronization therapy CT computed tomography 18 F-FDG fluorine-18 fluorodeoxyglucose 67 Ga gallium-67 HRCT high resolution computed tomography ICD implantable cardioverter defibrillator MRI magnetic resonance imaging PET positron emission tomography sIL-2R soluble interleukin 2 recepter SPECT single photon emission computed tomography JCS GUIDELINES

A major barrier to cancer treatment is the inability to deliver sufficient concentrations of drug to the tumor without incurring systemic toxicities. Nanomaterials are appealing because they can carry a large drug payload, however, tumor delivery is limited by modest leakage and retention in most tumors. We observed that after photoimmunotherapy (PIT), which is a light mediated treatment based on an antibody-photosensitizer conjugate, there was surprisingly high leakage of nanosized (10–200 nm) agents into the tumor bed. PIT rapidly induced death in perivascular cancer cells leading to immediate and dramatic increases in vascular permeability resulting in up to 24-fold greater accumulation of nanonanomaterials within the PIT-treated tumor compared with controls, an effect termed “super-enhanced permeability and retention” (SUPR). In a treatment study, PIT followed by liposome-containing daunorubicin, DaunoXome (diameter 50 nm), resulted in greater survival in tumor-bearing mice than either PIT or DaunoXome alone. Thus, PIT greatly enhances delivery of nanosized reagents and thus holds promise to improve therapeutic responses.

Armed antibody-based targeted molecular therapies offer the possibility of effective tumor control with a minimum of side effects. Photoimmunotherapy (PIT) employs a monoclonal antibody-phototoxic phthalocyanine dye, IR700 conjugate that is activated by focal near infrared (NIR) light irradiation after antibody binding to the targeted tumor cell surface leading to rapid necrotic cell death. Therapy by single NIR light irradiation was effective without significant side-effects, however, recurrences were seen in most of treated mice probably because of inhomogeneous distribution of panitumumab-IR700 immuno-conjugate in the tumor, leading to ineffective PIT. We describe here an optimized regimen of effective PIT method for the same HER1-overexpressing tumor model (A431) with fractionated administration of panitumumab-IR700 conjugate followed by systematic repeated NIR light irradiation to the tumor based on timing of antibody redistribution into the remnant tumor under the guidance of IR700 fluorescence signal. Eighty percents of the A431 tumors were eradicated with repeated PIT without apparent side effects and survived with tumor free more than 120 days even after stoping therapy at the day 30. Therapeutic effects were monitored using IR700 fluorescent signal. PIT is a promising highly selective and clinically feasible theranostics for the treatment of MAb-binding tumors with minimal off target effects.

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In patients with prostate cancer, a positive surgical margin is associated with an increased risk of cancer recurrence and poorer outcome, yet, margin status cannot be determined during the surgery. An in vivo optical imaging probe that could identify the tumor margins, during surgery, could result in improved outcomes. The design of such a probe focuses on a highly specific targeting moiety and a near infrared (NIR) fluorophore that is activated only when bound to the tumor. In this study, we successfully synthesized an activatable monoclonal antibody-fluorophore conjugate consisting of a humanized anti-prostate specific membrane antigen (PSMA) antibody (J591) linked to an indocyanine green ICG-derivative. Prior to binding to PSMA and cellular internalization, the conjugate yielded little light, however after binding an 18-fold activation was observed permitting the specific detection of PSMA+ tumors up to 10 days after injection of a low dose (0.25 mg/kg) of the reagent. This agent demonstrates promise as a method to image the extent of prostate cancer in vivo and could assist with real time resection of extracapsular extension of tumor.

Photoimmunotherapy (PIT) is a new cancer treatment that combines the specificity of antibodies for targeting tumors with the toxicity induced by photosensitizers after exposure to near infrared (NIR) light. Herein we compare two commonly available anti-EGFR monoclonal antibodies, cetuximab and panitumumab, for their effectiveness as PIT agents in EGFR positive tumor models. A photosensitizer, IR-700, conjugated to either cetuximab (cet-IR700) orpanitumumab (pan-IR700), was evaluated using EGFR-expressing A431 and MDAMB468-luc cells in 2D- and 3D-culture. PIT was conducted with irradiation of NIR light after exposure of the sample or animal to each conjugate. In vivo PIT was performed with fractionated exposure of NIR light after injection of each agent into A431 xenografts or a MDAMB468-luc orthotopic tumor bearing model. Cet-IR700 and pan-IR700 bound with equal affinity to the cells in 2D-culture and penetrated equally into the 3D-spheroid, resulting in identical PIT cytotoxic effects in vitro. In contrast, in vivo anti-tumor effects of PIT with cet-IR700 were inferior to that of pan-IR700. Assessment of the biodistribution showed lower accumulation into the tumors and more rapid hepatic catabolism of cet-IR700 compared to pan-IR700. Although cet-IR700 and pan-IR700 showed identical in vitro characteristics, pan-IR700 showed better therapeutic tumor responses than cet-IR700 in in vivo mice models due to the prolonged retention of the conjugate in the circulation, suggesting that retention in the circulation is advantageous for tumor responses to PIT. These results suggest that the choice of monoclonal antibody in photosensitizer conjugates may influence the effectiveness of PIT.

BackgroundNear infrared (NIR) photoimmunotherapy (PIT) is a new type of cancer treatment based on a monoclonal antibody (mAb)-NIR phthalocyanine dye, (IR700) conjugate. In vitro cancer-specific cell death occurs during NIR light exposure in cells previously incubated with mAb-IR700 conjugates. However, documenting rapid cell death in vivo is more difficult.MethodsA luciferase-transfected breast cancer cell (epidermal growth factor receptor+, MDA-MB-468luc cells) was produced and used for both in vitro and in vivo experiments for monitoring the cell killing effect of PIT. After validation of cytotoxicity with NIR exposure up to 8 J/cm2in vitro, we employed an orthotopic breast cancer model of bilateral MDA-MB-468luc tumors in female athymic mice, which subsequently received a panitumumab-IR700 conjugate in vivo. One side was used as a control, while the other was treated with NIR light of dose ranging from 50 to 150 J/cm2. Bioluminescence imaging (BLI) was performed before and after PIT.ResultsDose-dependent cell killing and regrowth was successfully monitored by the BLI signal in vitro. Although tumor sizes were unchanged, BLI signals decreased by >95% immediately after PIT in vivo when light intensity was high (>100 J/cm2), however, in mice receiving lower intensity NIR (50 J/cm2), tumors recurred with gradually increasing BLI signal.ConclusionPIT induced massive cell death of targeted tumor cells immediately after exposure of NIR light that was demonstrated with BLI in vivo.

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