Although therapeutic advances have led to enhanced survival in patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer, detection of residual disease remains challenging. Here, we examine two approved anti-HER2 monoclonal antibodies (mAbs), trastuzumab and pertuzumab, as potential candidates for the development of immunoconjugates for fluorescence-guided surgery (FGS).

BCL-2 inhibition through venetoclax (VEN) targets acute myeloid leukemia (AML) blast cells and leukemic stem cells (LSCs). Although VEN-containing regimens yield 60-70% clinical response rates, the vast majority of patients inevitably suffer disease relapse, likely because of the persistence of drug-resistant LSCs. We previously reported preclinical activity of the ribonucleoside analog 8-chloro-adenosine (8-Cl-Ado) against AML blast cells and LSCs. Moreover, our ongoing phase I clinical trial of 8-Cl-Ado in patients with refractory/relapsed AML demonstrates encouraging clinical benefit. Of note, LSCs uniquely depend on amino acid-driven and/or fatty acid oxidation (FAO)-driven oxidative phosphorylation (OXPHOS) for survival. VEN inhibits OXPHOS in LSCs, which eventually may escape the antileukemic activity of this drug. FAO is activated in LSCs isolated from patients with relapsed AML.

Cancer surgery remains the primary treatment option for most solid tumors and can be curative if all malignant cells are removed. Surgeons have historically relied on visual and tactile cues to maximize tumor resection, but clinical data suggest that relapse occurs partially due to incomplete cancer removal. As a result, the introduction of technologies that enhance the ability to visualize tumors in the operating room represents a pressing need. Such technologies have the potential to revolutionize the surgical standard-of-care by enabling real-time detection of surgical margins, subclinical residual disease, lymph node metastases and synchronous/metachronous tumors. Fluorescence-guided surgery (FGS) in the near-infrared (NIRF) spectrum has shown tremendous promise as an intraoperative imaging modality. An increasing number of clinical studies have demonstrated that tumor-selective FGS agents can improve the predictive value of fluorescence over non-targeted dyes. Whereas NIRF-labeled macromolecules (i.e., antibodies) spearheaded the widespread clinical translation of tumor-selective FGS drugs, peptides and small-molecules are emerging as valuable alternatives. Here, we first review the state-of-the-art of promising low molecular weight agents that are in clinical development for FGS; we then discuss the significance, application and constraints of emerging tumor-selective FGS technologies.

The use of cancer-targeted contrast agents in fluorescence-guided surgery (FGS) has the potential to improve intraoperative visualization of tumors and surgical margins. However, evaluation of their translational potential is challenging.

Dye design can influence the ability of fluorescently labeled imaging agents to generate tumor contrast and has become an area of significant interest in the field of fluorescence-guided surgery (FGS). Here, we show that the charge-balanced near-infrared fluorescent (NIRF) dye FNIR-Tag enhances the imaging properties of a fluorescently labeled somatostatin analogue. In vitro studies showed that the optimized fluorescent conjugate MMC(FNIR-Tag)-TOC bound primarily via somatostatin receptor subtype-2 (SSTR2), whereas its negatively charged counterpart with IRDye 800CW had higher off-target binding. NIRF imaging in cell line- and patient-derived xenograft models revealed markedly higher tumor contrast with MMC(FNIR-Tag)-TOC, which was attributed to increased tumor specificity. Ex vivo staining of surgical biospecimens from primary and metastatic tumors, as well as involved lymph nodes, demonstrated binding to human tumors. Finally, in an orthotopic tumor model, a simulated clinical workflow highlighted our unique ability to use standard preoperative nuclear imaging for selecting patients likely to benefit from SSTR2-targeted FGS. Our findings demonstrate the translational potential of MMC(FNIR-Tag)-TOC for intraoperative imaging and suggest broad utility for using FNIR-Tag in fluorescent probe development.