Imaging methods to evaluate tumor microenvironment factors affecting nanoparticle drug delivery and antitumor response

Single-cell spatial immune profiling for precision immunotherapy in Lynch syndrome

Lynch syndrome (LS) is the most common hereditary colorectal cancer (CRC) predisposition syndrome, characterized by a high mutational burden and microsatellite instability-high (MSI-H) tumors. Immunology of LS-associated CRC (LS-CRC) is unique, with significant implications for treatment. Despite well-established knowledge of LS immunology, immunotherapy dose and treatment response can vary significantly based on local tumor immunity and specific germline pathogenic variant of LS genes. This variability necessitates tailored surveillance strategies and new personalised immunotherapy approaches for LS patients. LS-CRC often benefits from immunotherapy due to the distinct tumor microenvironment (TME) and the variety of tumor infiltrating lymphocytes (TILs). This perspective discusses a novel approach of analysing spatial TILs at a single-cell level using tumor whole slide images (WSIs) that accounts for the distinct TME of LS-CRC. By emphasizing the necessity of personalized medicine in hereditary cancer syndromes, the future research and clinical practices that enhance patient outcomes through precision oncology is inspired.

Assessing Therapeutic Nanoparticle Accumulation in Tumors Using Nanobubble-Based Contrast-Enhanced Ultrasound Imaging

This study explores the challenges associated with nanoparticle-based drug delivery to the tumor parenchyma, focusing on the widely utilized enhanced permeability and retention effect (EPR). While EPR has been a key strategy, its inconsistent clinical success lacks clear mechanistic understanding and is hindered by limited tools for studying relevant phenomena. This work introduces an approach that employs multiparametric dynamic contrast-enhanced ultrasound (CEUS) with a nanoscale contrast agent for noninvasive, real-time examination of tumor microenvironment characteristics. We demonstrate that CEUS imaging can: (1) evaluate tumor microenvironment features, (2) be used to help predict the distribution of doxorubicin-loaded liposomes in the tumor parenchyma, and (3) be used to predict nanotherapeutic efficacy. CEUS using nanobubbles (NBs) was carried out in two tumor types of high (LS174T) and low (U87) vascular permeability. LS174T tumors consistently showed significantly different time intensity curve (TIC) parameters, including area under the rising curve (AUCR, 2.7×) and time to peak intensity (TTP, 1.9×) compared to U87 tumors. Crucially, a recently developed decorrelation time (DT) parameter specific to NB CEUS dynamics successfully predicted the distribution of doxorubicin-loaded liposomes within the tumor parenchyma (r = 0.86 ± 0.13). AUCR, TTP, and DT were used to correlate imaging findings to nanotherapeutic response with 100% accuracy in SKOV-3 tumors. These findings suggest that NB-CEUS parameters can effectively discern tumor vascular permeability, serving as a biomarker for identifying tumor characteristics and predicting the responsiveness to nanoparticle-based therapies. The observed differences between LS174T and U87 tumors and the accurate prediction of nanotherapeutic efficacy in SKOV-3 tumors indicate the potential utility of this method in predicting treatment efficacy and evaluating EPR in diseases characterized by pathologically permeable vasculature. Ultimately, this research contributes valuable insights into refining drug delivery strategies and assessing the broader applicability of EPR-based approaches.

Innovative optical imaging strategies for monitoring immunotherapy in the tumor microenvironments

BACKGROUND

The tumor microenvironment (TME) plays a critical role in cancer progression and response to immunotherapy. Immunotherapy targeting the immune system has emerged as a promising treatment modality, but challenges in understanding the TME limit its efficacy. Optical imaging strategies offer noninvasive, real-time insights into the interactions between immune cells and the TME.

OBJECTIVE

This review assesses the progress of optical imaging technologies in monitoring immunotherapy within the TME and explores their potential applications in clinical trials and personalized cancer treatment.

METHODS

This is a comprehensive literature review based on the advances in optical imaging modalities including fluorescence imaging (FLI), bioluminescence imaging (BLI), and photoacoustic imaging (PAI). These modalities were analyzed for their capacity to provide high-resolution, real-time imaging of immune cell dynamics, tumor vasculature, and other critical components of the TME.

RESULTS

Optical imaging techniques have shown significant potential in tracking immune cell infiltration, assessing immune checkpoint inhibitors, and visualizing drug delivery within the TME. Technologies like FLI and BLI are pivotal in tracking immune responses in preclinical models, while PAI provides functional imaging with deeper tissue penetration. The integration of these modalities with immunotherapy holds promise for improving treatment monitoring and outcomes.

CONCLUSION

Optical imaging is a powerful tool for understanding the complexities of the TME and optimizing immunotherapy. Further advancements in imaging technologies, combined with nanomaterial-based approaches, could pave the way for enhanced diagnostic accuracy and therapeutic efficacy in cancer treatment.

Using imaging modalities to predict nanoparticle distribution and treatment efficacy in solid tumors: The growing role of ultrasound

Nanomedicine in oncology has not had the success in clinical impact that was anticipated in the early stages of the field's development. Ideally, nanomedicines selectively accumulate in tumor tissue and reduce systemic side effects compared to traditional chemotherapeutics. However, this has been more successful in preclinical animal models than in humans. The causes of this failure to translate may be related to the intra- and inter-patient heterogeneity of the tumor microenvironment. Predicting whether a patient will respond positively to treatment prior to its initiation, through evaluation of characteristics like nanoparticle extravasation and retention potential in the tumor, may be a way to improve nanomedicine success rate. While there are many potential strategies to accomplish this, prediction and patient stratification via noninvasive medical imaging may be the most efficient and specific strategy. There have been some preclinical and clinical advances in this area using MRI, CT, PET, and other modalities. An alternative approach that has not been studied as extensively is biomedical ultrasound, including techniques such as multiparametric contrast-enhanced ultrasound (mpCEUS), doppler, elastography, and super-resolution processing. Ultrasound is safe, inexpensive, noninvasive, and capable of imaging the entire tumor with high temporal and spatial resolution. In this work, we summarize the in vivo imaging tools that have been used to predict nanoparticle distribution and treatment efficacy in oncology. We emphasize ultrasound imaging and the recent developments in the field concerning CEUS. The successful implementation of an imaging strategy for prediction of nanoparticle accumulation in tumors could lead to increased clinical translation of nanomedicines, and subsequently, improved patient outcomes. This article is categorized under: Diagnostic Tools In Vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery Nanomedicine for Oncologic Disease Therapeutic Approaches and Drug Discovery Emerging Technologies.