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Determination of treatment response to immunotherapy in glioblastoma multiforme (GBM) is a process which can take months. Detection of CD8+ T cell recruitment to the tumor with a noninvasive imaging modality such as positron emission tomography (PET) may allow for tumor characterization and early evaluation of therapeutic response to immunotherapy. In this study, we utilized 89Zr-labeled anti-CD8 cys-diabody-PET to provide proof-of-concept to detect CD8+ T cell immune response to oncolytic herpes simplex virus (oHSV) M002 immunotherapy in a syngeneic GBM model. Immunocompetent mice (n = 16) were implanted intracranially with GSC005 GBM tumors, and treated with intratumoral injection of oHSV M002 or saline control. An additional non-tumor bearing cohort (n = 4) receiving oHSV M002 treatment was also evaluated. Mice were injected with 89Zr-labeled anti-CD8 cys-diabody seven days post oHSV administration and imaged with a preclinical PET scanner. Standardized uptake value (SUV) was quantified. Ex vivo tissue analyses included autoradiography and immunohistochemistry. PET imaging showed significantly higher SUV in tumors which had been treated with M002 compared to those without M002 treatment (p = 0.0207) and the non-tumor bearing M002 treated group (p = 0.0021). Accumulation in target areas, especially the spleen, was significantly reduced by blocking with the non-labeled diabody (p < 0.001). Radioactive probe accumulation in brains was consistent with CD8+ cell trafficking patterns after oHSV treatment. This PET imaging strategy could aid in distinguishing responders from non-responders during immunotherapy of GBM. [ABSTRACT FROM AUTHOR]

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer with a poor prognosis. There is a clinical need for effective, targeted therapy strategies that destroy both differentiated TNBC cells and TNBC cancer initiating cells (CICs), as the latter are implicated in the metastasis and recurrence of TNBC. Chondroitin sulfate proteoglycan 4 (CSPG4) is overexpressed on differentiated tumor cells and CICs obtained from TNBC patient specimens, suggesting that CSPG4 may be a clinically relevant target for the imaging and therapy of TNBC. The purpose of this study was to determine whether α-particle radioimmunotherapy (RIT) targeting TNBC cells using the CSPG4-specific monoclonal antibody (mAb) 225.28 as a carrier was effective at eliminating TNBC tumors in preclinical models. To this end, mAb 225.28 labeled with 212Pb (212Pb-225.28) as a source of α-particles for RIT was used for in vitro Scatchard assays and clonogenic survival assays with human TNBC cells (SUM159 and 2LMP) grown as adherent cells or non-adherent CIC-enriched mammospheres. Immune-deficient mice bearing orthotopic SUM159 or 2LMP xenografts were injected i.v. with the targeted (225.28) or irrelevant isotype-matched control (F3-C25) mAbs, labeled with 99mTc, 125I, or 212Pb for in vivo imaging, biodistribution, or tumor growth inhibition studies. 212Pb-225.28 bound to adherent SUM159 and 2LMP cells and to CICs from SUM159 and 2LMP mammospheres with a mean affinity of 0.5 nM. Nearly ten times more binding sites per cell were present on SUM159 cells and CICs compared with 2LMP cells. 212Pb-225.28 was six to seven times more effective than 212Pb-F3-C25 at inhibiting SUM159 cell and CIC clonogenic survival (p < 0.05). Radiolabeled mAb 225.28 showed significantly higher uptake than radiolabeled mAb F3-C25 in SUM159 and 2LMP xenografts (p < 0.05), and the uptake of 212Pb-225.28 in TNBC xenografts was correlated with target epitope expression. 212Pb-225.28 caused dose-dependent growth inhibition of SUM159 xenografts; 0.30 MBq 212Pb-225.28 was significantly more effective than 0.33 MBq 212Pb-F3-C25 at inhibiting tumor growth (p < 0.01). These results suggest that CSPG4-specific 212Pb-225.28 is a useful reagent for RIT of CSPG4-expressing tumors, including metastatic TNBC. [ABSTRACT FROM AUTHOR]

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer with a poor prognosis. There is a clinical need for effective, targeted therapy strategies that destroy both differentiated TNBC cells and TNBC cancer initiating cells (CICs), as the latter are implicated in the metastasis and recurrence of TNBC. Chondroitin sulfate proteoglycan 4 (CSPG4) is overexpressed on differentiated tumor cells and CICs obtained from TNBC patient specimens, suggesting that CSPG4 may be a clinically relevant target for the imaging and therapy of TNBC. The purpose of this study was to determine whether α-particle radioimmunotherapy (RIT) targeting TNBC cells using the CSPG4-specific monoclonal antibody (mAb) 225.28 as a carrier was effective at eliminating TNBC tumors in preclinical models. To this end, mAb 225.28 labeled with 212Pb (212Pb-225.28) as a source of α-particles for RIT was used for in vitro Scatchard assays and clonogenic survival assays with human TNBC cells (SUM159 and 2LMP) grown as adherent cells or non-adherent CIC-enriched mammospheres. Immune-deficient mice bearing orthotopic SUM159 or 2LMP xenografts were injected i.v. with the targeted (225.28) or irrelevant isotype-matched control (F3-C25) mAbs, labeled with 99mTc, 125I, or 212Pb for in vivo imaging, biodistribution, or tumor growth inhibition studies. 212Pb-225.28 bound to adherent SUM159 and 2LMP cells and to CICs from SUM159 and 2LMP mammospheres with a mean affinity of 0.5 nM. Nearly ten times more binding sites per cell were present on SUM159 cells and CICs compared with 2LMP cells. 212Pb-225.28 was six to seven times more effective than 212Pb-F3-C25 at inhibiting SUM159 cell and CIC clonogenic survival (p < 0.05). Radiolabeled mAb 225.28 showed significantly higher uptake than radiolabeled mAb F3-C25 in SUM159 and 2LMP xenografts (p < 0.05), and the uptake of 212Pb-225.28 in TNBC xenografts was correlated with target epitope expression. 212Pb-225.28 caused dose-dependent growth inhibition of SUM159 xenografts; 0.30 MBq 212Pb-225.28 was significantly more effective than 0.33 MBq 212Pb-F3-C25 at inhibiting tumor growth (p < 0.01). These results suggest that CSPG4-specific 212Pb-225.28 is a useful reagent for RIT of CSPG4-expressing tumors, including metastatic TNBC.

A fluorescent tridentate phosphine, BodP3 (2), forms rhenium complexes which effectively image cancer cells. Related technetium analogues are also readily prepared and have potential as dual SPECT/fluorescent biological probes. [ABSTRACT FROM AUTHOR]

Isoxazole ring formation was examined as a potential Cu-free alternative click reaction to CuI-catalyzed alkyne/azide cycloaddition. The isoxazole reaction was explored at macroscopic and radiotracer concentrations with the fac-[MI(CO)3]+ (M = Re, 99mTc) core for use as a noncoordinating linker strategy between covalently linked molecules. Two click assembly methods (click, then chelate and chelate, then click) were examined to determine the feasibility of isoxazole ring formation with either alkyne-functionalized tridentate chelates or their respective fac-[MI(CO)3]+ complexes with a model nitrile oxide generator. Macroscale experiments, alkyne-functionalized chelates, or Re complexes indicate facile formation of the isoxazole ring. 99mTc experiments demonstrate efficient radiolabeling with click, then chelate; however, the chelate, then click approach led to faster product formation, but lower yields compared to the Re analogues. [ABSTRACT FROM AUTHOR]

Purpose: The incidence of oropharyngeal squamous cell carcinoma (OPSCC) has continually increased during the past several decades. Using transoral robotic surgery (TORS) significantly improves functional outcomes relative to open surgery for OPSCC. However, TORS limits tactile feedback, which is often the most important element of cancer surgery. Fluorescence-guided surgery (FGS) strategies to aid surgeon assessment of malignancy for resection are in various phases of clinical research but exhibit the greatest potential impact for improving patient care when the surgeon receives limited tactile feedback, such as during TORS. Here, we assessed the feasibility of intraoperative fluorescence imaging using panitumumab-IRDye800CW (PAN800) during TORS in patients with OPSCC., Patients and Methods: Twelve consecutive patients with OPSCC were enrolled as part of a nonrandomized, prospective, phase II FGS clinical trial using PAN800. TORS was performed with an integrated robot camera for surgeon assessment of fluorescence. Intraoperative and ex vivo fluorescence signals in tumors and normal tissue were quantified and correlated with histopathology., Results: Intraoperative robot fluorescence views delineated OPSCC from normal tissue throughout the TORS procedure (10.7 mean tumor-to-background ratio), including in tumors with low expression of the molecular target. Tumor-specific fluorescence was consistent with surgeon-defined tumor borders requiring resection. Intraoperative robot fluorescence imaging revealed an OPSCC fragment initially overlooked during TORS based on brightfield views, further substantiating the clinical benefit of this FGS approach., Conclusions: The results from this patient with OPSCC cohort support further clinical assessment of FGS during TORS to aid resection of solid tumors., (©2024 American Association for Cancer Research.)

Background: Axial pattern flaps are a common reconstructive option following resection of soft tissue malignancies. We determine the early dependence of an axial flap on wound bed vasculature by isolating the underlying wound bed and depriving contact with the overlying flap. Materials and Methods: Mice were divided into 5 groups: No silicone (n = 7), silicone in the proximal 50% of the wound bed (n = 8), silicone in the distal 50% of the wound bed (n = 5), silicone over the full length of the wound bed with pedicle preservation (n = 5), and silicone over the full length of the wound bed with pedicle sacrifice (n = 5). The pedicle was the lateral thoracic artery. Daily photographs were taken, and the percent of viable flap was determined using ImageJ© software (public domain JAVA image processing program, National Institute of Health, Bethesda, MA). Percent flap viability for each group was compared to the no silicone group, which acted as the reference. Results: Mean differences in percent flap necrotic area (with 95% confidence interval) compared to the no silicone group were -0.15% (-15.09 to 14.09), 2.07% (-5.26 to 9.39), 2.98% (-10.98 to 16.94), and 14.21% (0.48 to 27.94) for the full-length silicone with preserved pedicle, proximal silicone, distal silicone, and full-length silicone with sacrificed pedicle groups, respectively. The full-length silicone with sacrificed pedicle group had a significant difference in flap viability ( P  = .045) compared to the no silicone group. Conclusion: We investigate the role of the wound bed vasculature in a murine axial flap model and demonstrate that the wound bed vasculature is not essential for early distal flap survival., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Developing new strategies to rapidly incorporate the fac-[M(I)(CO)3](+) (M = Re, (99m)Tc) core into biological targeting vectors in radiopharmaceuticals continues to expand as molecules become more complex and as efforts to minimize nonspecific binding increase. This work examines a novel isothiocyanate-functionalized bifunctional chelate based on 2,2'-dipicolylamine (DPA) specifically designed for complexing the fac-[M(I)(CO)3](+) core. Two strategies (postlabeling and prelabeling) were explored using the isothiocyanate-functionalized DPA to determine the effectiveness of assembly on the overall yield and purity of the complex with amine containing biomolecules. A model amino acid (lysine) examined (1) amine conjugation of isothiocyanate-functionalized DPA followed by complexation with fac-[M(I)(CO)3](+) (postlabeling) and (2) complexation of fac-[M(I)(CO)3](+) with isothiocyanate-functionalized DPA followed by amine conjugation (prelabeling). Conducted with stable Re and radioactive (99m)Tc analogs, both strategies formed the product in good to excellent yields under macroscopic and radiotracer concentrations. A synthetic peptide (AE105) which targets an emerging biomarker in CaP prognosis, urokinase-type plasminogen activator receptor (uPAR), was also explored using the isothiocyanate-functionalized DPA strategy. In vitro PC-3 (uPAR+) cell uptake assays with the (99m)Tc-labeled peptide (8a) showed 4.2 ± 0.5% uptake at 4 h. In a murine model bearing PC-3 tumor xenografts, in vivo biodistribution of 8a led to favorable tumor uptake (3.7 ± 0.7% ID/g) at 4 h p.i. with relatively low accumulation (<2% ID/g) in normal organs not associated with normal peptide excretion. These results illustrate the promise of the isothiocyanate-functionalized approach for labeling amine containing biological targeting vectors with fac-[M(I)(CO)3](+)., Competing Interests: Notes The authors declare no competing financial interest.

A fluorescent tridentate phosphine, BodP3 (2), forms rhenium complexes which effectively image cancer cells. Related technetium analogues are also readily prepared and have potential as dual SPECT/fluorescent biological probes.