Molecular imaging for personalized cancer care

Molecular Imaging Biomarkers for Early Cancer Detection: A Systematic Review of Emerging Technologies and Clinical Applications

BACKGROUND

Early cancer detection is crucial for improving patient outcomes. Molecular imaging biomarkers offer the potential for non-invasive, early-stage cancer diagnosis.

OBJECTIVES

To evaluate the effectiveness and accuracy of molecular imaging biomarkers for early cancer detection across various imaging modalities and cancer types.

METHODS

A comprehensive search of PubMed/MEDLINE, Embase, Web of Science, Cochrane Library, and Scopus was performed, covering the period from January 2010 to December 2023. Eligibility criteria included original research articles published in English on molecular imaging biomarkers for early cancer detection in humans. The risk of bias for included studies was evaluated using the QUADAS-2 tool. The findings were synthesized through narrative synthesis, with quantitative analysis conducted where applicable.

RESULTS

In total, 50 studies were included. Positron emission tomography (PET)-based biomarkers showed the highest sensitivity (mean: 89.5%, range: 82-96%) and specificity (mean: 91.2%, range: 85-100%). Novel tracers such as [68Ga]-PSMA for prostate cancer and [18F]-FES for breast cancer demonstrated promising outcomes. Optical imaging techniques showed high specificity in intraoperative settings.

CONCLUSIONS

Molecular imaging biomarkers show significant potential for improving early cancer detection. Integration into clinical practice could lead to earlier interventions and improved outcomes. Further research is needed to address standardization and cost-effectiveness.

Ex vivo optical coherence tomography combined with near infrared targeted fluorescence: towards in-vivo esophageal cancer detection

Early detection of (pre)malignant esophageal lesions is critical to improve esophageal cancer morbidity and mortality rates. In patients with advanced esophageal adenocarcinoma (EAC) who undergo neoadjuvant chemoradiation therapy, the efficacy of therapy could be optimized and unnecessary surgery prevented by the reliable assessment of residual tumors after therapy. Optical coherence tomography (OCT) provides structural images at a (sub)-cellular level and has the potential to visualize morphological changes in tissue. However, OCT lacks molecular imaging contrast, a feature that enables the study of biological processes at a cellular level and can enhance esophageal cancer diagnostic accuracy. We combined OCT with near-infrared fluorescence molecular imaging using fluorescently labelled antibodies (immuno-OCT). The main goal of this proof of principle study is to investigate the feasibility of immuno-OCT for esophageal cancer imaging. We aim to assess whether the sensitivity of our immuno-OCT device is sufficient to detect the tracer uptake using an imaging dose (∼100 times smaller than a dose with therapeutic effects) of a targeted fluorescent agent. The feasibility of immuno-OCT was demonstrated ex-vivo on dysplastic lesions resected from Barrett's patients and on esophageal specimens resected from patients with advanced EAC, who were respectively topically and intravenously administrated with the tracer bevacizumab-800CW. The detection sensitivity of our system (0.3 nM) is sufficient to detect increased tracer uptake with micrometer resolution using an imaging dose of labelled antibodies. Moreover, the absence of layered structures that are typical of normal esophageal tissue observed in OCT images of dysplastic/malignant esophageal lesions may further aid their detection. Based on our preliminary results, immuno-OCT could improve the detection of dysplastic esophageal lesions.

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.

Nanotechnology in cancer therapeutics, diagnosis, and management

Nanotechnology presents an exciting opportunity in cancer research by offering significant advancements in therapies, diagnosis, and management. It possesses unparalleled potential to enhance the accuracy and effectiveness of cancer therapy while simultaneously reducing adverse effects, owing to its distinctive capability to manipulate matter at a molecular level. Using nanoparticle carriers has facilitated the precise administration of therapeutic agents to afflicted areas within the human body through customized drug delivery systems, resulting in improved treatment accuracy and efficacy while reducing adverse effects. These techniques improve drug solubility and stability, leading to elevated levels of biochemical availability and improved efficacy outcomes for patients with minimal negative effects during treatment cycles. Another use case for nanoparticles includes tumor imaging; functionalized with targeting ligands containing diagnostic agents, they foster early detection, making quicker remedial action plans possible. Overall, the incorporation of nanotechnology ensures a promising future, although it stresses the need to address regulatory hurdles and safety concerns before widespread clinical implementation. Despite the complexity of cancer research and patient care, nanotechnology shows promise in transforming both fields.

Bridging the Divide: A Review on the Implementation of Personalized Cancer Medicine

The shift towards personalized cancer medicine (PCM) represents a significant transformation in cancer care, emphasizing tailored treatments based on the genetic understanding of cancer at the cellular level. This review draws on recent literature to explore key factors influencing PCM implementation, highlighting the role of innovative leadership, interdisciplinary collaboration, and coordinated funding and regulatory strategies. Success in PCM relies on overcoming challenges such as integrating diverse medical disciplines, securing sustainable investment for shared infrastructures, and navigating complex regulatory landscapes. Effective leadership is crucial for fostering a culture of innovation and teamwork, essential for translating complex biological insights into personalized treatment strategies. The transition to PCM necessitates not only organizational adaptation but also the development of new professional roles and training programs, underscoring the need for a multidisciplinary approach and the importance of team science in overcoming the limitations of traditional medical paradigms. The conclusion underscores that PCM's success hinges on creating collaborative environments that support innovation, adaptability, and shared vision among all stakeholders involved in cancer care.

The Basics of Visualizing, Analyzing, and Reporting Preclinical PET/CT Imaging Data

Positron emission tomography (PET) has transformed medical imaging, and while first developed and applied to the human setting, it has found widespread application at the preclinical level over the past two decades. Its strength is that it offers noninvasive 3D tomographic imaging in a quantitative manner at very high sensitivity. Paired with the right molecular probes, invaluable insights into physiology and pathophysiology have been accessible and therapeutic development has been enhanced through preclinical PET imaging. PET imaging is now often routinely combined with either computed tomography (CT) or magnetic resonance imaging (MRI) to provide additional anatomical context. All these developments were accompanied by the provision of ever more complex and powerful analysis software enabling users to visualize and quantify signals from PET imaging data. Aside from experimental complexities, there are also various pitfalls in PET image data analysis, which can negatively impact on reporting and reproducibility.Here, we provide a protocol intended to guide the inexperienced user through PET/CT data analysis. We describe the general principles and workflows required for PET/CT image data visualization and quantitative analysis using various software packages popular in the field. Moreover, we present recommendations for reporting of preclinical PET/CT data including examples of good and poor practice.

Radiometal Complexes as Pharmacokinetic Modifiers: A Potent 68Ga-Labeled Gastrin-Releasing Peptide Receptor Antagonist Based on the Macrocyclic Metal Chelator NODIA-Me

The gastrin-releasing peptide receptor (GRPr) is overexpressed in various cancer types including prostate and breast carcinomas, making it an attractive target for molecular imaging and therapy. In this work, we designed a novel GRPr antagonistic probe comprising metal chelator NODIA-Me. This 1,4,7-triazacyclononane-based chelator forms positively charged metal complexes due to its neutral methylimidazole arms. Because a positive charge at the N-terminus of GRPr conjugates is responsible for high receptor affinity as exemplified by the current gold standard DOTA-RM2, we investigated if a positively charged radiometal complex can be used as a pharmacokinetic modifier to also produce high-affinity GRPr conjugates. In this respect, the bioconjugate NODIA-Me-Ahx-JMV594 was prepared by a combination of solid-phase peptide synthesis and solution-based reactions in a 94% yield. Radiolabeling provided the 68Ga-labeled conjugate in radiochemical yields of >95% and radiochemical purities of >98% with mean molar activities of Am ∼17 MBq nmol-1. The competitive GRPr affinity of the metal-free and 69/71Ga-labeled conjugate was determined to be IC50 = 0.41 ± 0.06 and 1.45 ± 0.06 nM, respectively. The metal-free GRPr antagonist DOTA-RM2 and its corresponding 69/71Ga complex had IC50 values of 1.42 ± 0.07 and 0.98 ± 0.19 nM, respectively. Small-animal PET imaging of mice bearing GRPr(+) PC-3 tumors revealed high radioactivity accumulation in the tumors and in the pancreas as an organ with high levels of GRPr expression. These findings were corroborated by the corresponding ex vivo biodistribution data, in which the tumors and the pancreas exhibited the highest radioactivity accumulation. By coinjection of an excess of NODIA-Me-Ahx-JMV594, uptake in the tumors and GRPr(+) organs was significantly reduced, confirming specific receptor-mediated uptake. The estrogen receptor-positive tumor of a female breast cancer patient was clearly visualized by PET imaging using 68Ga-labeled NODIA-Me-Ahx-JMV594. To summarize, the positive charge at the N-terminus of the conjugate induced by the Ga(NODIA-Me) complex resulted in high GRPr affinity comparable to that of the potent antagonist DOTA-RM2. The conjugate NODIA-Me-Ahx-JMV594 is a promising probe for imaging of GRPr tumors that warrants further evaluation in larger patient cohorts as well as in combination with other radiometals.

In vivo nanoparticle-based T cell imaging can predict therapy response towards adoptive T cell therapy in experimental glioma

Rationale: Intrinsic brain tumors, such as gliomas are largely resistant to immunotherapies including immune checkpoint blockade. Adoptive cell therapies (ACT) including chimeric antigen receptor (CAR) or T cell receptor (TCR)-transgenic T cell therapy targeting glioma-associated antigens are an emerging field in glioma immunotherapy. However, imaging techniques for non-invasive monitoring of adoptively transferred T cells homing to the glioma microenvironment are currently lacking. Methods: Ultrasmall iron oxide nanoparticles (NP) can be visualized non-invasively by magnetic resonance imaging (MRI) and dedicated MRI sequences such as T2* mapping. Here, we develop a protocol for efficient ex vivo labeling of murine and human TCR-transgenic and CAR T cells with iron oxide NPs. We assess labeling efficiency and T cell functionality by flow cytometry and transmission electron microscopy (TEM). NP labeled T cells are visualized by MRI at 9.4 T in vivo after adoptive T cell transfer and correlated with 3D models of cleared brains obtained by light sheet microscopy (LSM). Results: NP are incorporated into T cells in subcellular cytoplasmic vesicles with high labeling efficiency without interfering with T cell viability, proliferation and effector function as assessed by cytokine secretion and antigen-specific killing assays in vitro. We further demonstrate that adoptively transferred T cells can be longitudinally monitored intratumorally by high field MRI at 9.4 Tesla in a murine glioma model with high sensitivity. We find that T cell influx and homogenous spatial distribution of T cells within the TME as assessed by T2* imaging predicts tumor response to ACT whereas incomplete T cell coverage results in treatment resistance. Conclusion: This study showcases a rational for monitoring adoptive T cell therapies non-invasively by iron oxide NP in gliomas to track intratumoral T cell influx and ultimately predict treatment outcome.

Machine Learning of Multi-Modal Tumor Imaging Reveals Trajectories of Response to Precision Treatment

The standard assessment of response to cancer treatments is based on gross tumor characteristics, such as tumor size or glycolysis, which provide very indirect information about the effect of precision treatments on the pharmacological targets of tumors. Several advanced imaging modalities allow for the visualization of targeted tumor hallmarks. Descriptors extracted from these images can help establishing new classifications of precision treatment response. We propose a machine learning (ML) framework to analyze metabolic-anatomical-vascular imaging features from positron emission tomography, ultrafast Doppler, and computed tomography in a mouse model of paraganglioma undergoing anti-angiogenic treatment with sunitinib. Imaging features from the follow-up of sunitinib-treated (n = 8, imaged once-per-week/6-weeks) and sham-treated (n = 8, imaged once-per-week/3-weeks) mice groups were dimensionally reduced and analyzed with hierarchical clustering Analysis (HCA). The classes extracted from HCA were used with 10 ML classifiers to find a generalized tumor stage prediction model, which was validated with an independent dataset of sunitinib-treated mice. HCA provided three stages of treatment response that were validated using the best-performing ML classifier. The Gaussian naive Bayes classifier showed the best performance, with a training accuracy of 98.7 and an average area under curve of 100. Our results show that metabolic-anatomical-vascular markers allow defining treatment response trajectories that reflect the efficacy of an anti-angiogenic drug on the tumor target hallmark.

Nanoparticles in the diagnosis and treatment of cancer metastases: Current and future perspectives

Metastasis accounts for greater than 90% of cancer-related deaths. Despite recent advancements in conventional chemotherapy, immunotherapy, targeted therapy, and their rational combinations, metastatic cancers remain essentially untreatable. The distinct obstacles to treat metastases include their small size, high multiplicity, redundancy, therapeutic resistance, and dissemination to multiple organs. Recent advancements in nanotechnology provide the numerous applications in the diagnosis and prophylaxis of metastatic diseases, including the small particle size to penetrate cell membrane and blood vessels and their capacity to transport complex molecular 'cargo' particles to various metastatic regions such as bones, brain, liver, lungs, and lymph nodes. Indeed, nanoparticles (NPs) have demonstrated a significant ability to target specific cells within these organs. In this regard, the purpose of this review is to summarize the present state of nanotechnology in terms of its application in the diagnosis and treatment of metastatic cancer. We intensively reviewed applications of NPs in fluorescent imaging, PET scanning, MRI, and photoacoustic imaging to detect metastasis in various cancer models. The use of targeted NPs for cancer ablation in conjunction with chemotherapy, photothermal treatment, immuno therapy, and combination therapy is thoroughly discussed. The current review also highlights the research opportunities and challenges of leveraging engineering technologies with cancer cell biology and pharmacology to fabricate nanoscience-based tools for treating metastases.

The Role of Molecular Imaging in Personalized Medicine

The concept of personalized medicine refers to the tailoring of medical treatment to each patient's unique characteristics. Scientific advancements have led to a better understanding of how a person's unique molecular and genetic profile makes them susceptible to certain diseases. It provides individualized medical treatments that will be safe and effective for each patient. Molecular imaging modalities play an essential role in this aspect. They are used widely in screening, detection and diagnosis, treatment, assessing disease heterogeneity and progression planning, molecular characteristics, and long-term follow-up. In contrast to conventional imaging approaches, molecular imaging techniques approach images as the knowledge that can be processed, allowing for the collection of relevant knowledge in addition to the evaluation of enormous patient groups. This review presents the fundamental role of molecular imaging modalities in personalized medicine.

Automated data preparation for in vivo tumor characterization with machine learning

Background

This study proposes machine learning-driven data preparation (MLDP) for optimal data preparation (DP) prior to building prediction models for cancer cohorts.

Methods

A collection of well-established DP methods were incorporated for building the DP pipelines for various clinical cohorts prior to machine learning. Evolutionary algorithm principles combined with hyperparameter optimization were employed to iteratively select the best fitting subset of data preparation algorithms for the given dataset. The proposed method was validated for glioma and prostate single center cohorts by 100-fold Monte Carlo (MC) cross-validation scheme with 80-20% training-validation split ratio. In addition, a dual-center diffuse large B-cell lymphoma (DLBCL) cohort was utilized with Center 1 as training and Center 2 as independent validation datasets to predict cohort-specific clinical endpoints. Five machine learning (ML) classifiers were employed for building prediction models across all analyzed cohorts. Predictive performance was estimated by confusion matrix analytics over the validation sets of each cohort. The performance of each model with and without MLDP, as well as with manually-defined DP were compared in each of the four cohorts.

Results

Sixteen of twenty established predictive models demonstrated area under the receiver operator characteristics curve (AUC) performance increase utilizing the MLDP. The MLDP resulted in the highest performance increase for random forest (RF) (+0.16 AUC) and support vector machine (SVM) (+0.13 AUC) model schemes for predicting 36-months survival in the glioma cohort. Single center cohorts resulted in complex (6-7 DP steps) DP pipelines, with a high occurrence of outlier detection, feature selection and synthetic majority oversampling technique (SMOTE). In contrast, the optimal DP pipeline for the dual-center DLBCL cohort only included outlier detection and SMOTE DP steps.

Conclusions

This study demonstrates that data preparation prior to ML prediction model building in cancer cohorts shall be ML-driven itself, yielding optimal prediction models in both single and multi-centric settings.

Therapy resistance: opportunities created by adaptive responses to targeted therapies in cancer

Normal cells explore multiple states to survive stresses encountered during development and self-renewal as well as environmental stresses such as starvation, DNA damage, toxins or infection. Cancer cells co-opt normal stress mitigation pathways to survive stresses that accompany tumour initiation, progression, metastasis and immune evasion. Cancer therapies accentuate cancer cell stresses and invoke rapid non-genomic stress mitigation processes that maintain cell viability and thus represent key targetable resistance mechanisms. In this Review, we describe mechanisms by which tumour ecosystems, including cancer cells, immune cells and stroma, adapt to therapeutic stresses and describe three different approaches to exploit stress mitigation processes: (1) interdict stress mitigation to induce cell death; (2) increase stress to induce cellular catastrophe; and (3) exploit emergent vulnerabilities in cancer cells and cells of the tumour microenvironment. We review challenges associated with tumour heterogeneity, prioritizing actionable adaptive responses for optimal therapeutic outcomes, and development of an integrative framework to identify and target vulnerabilities that arise from adaptive responses and engagement of stress mitigation pathways. Finally, we discuss the need to monitor adaptive responses across multiple scales and translation of combination therapies designed to take advantage of adaptive responses and stress mitigation pathways to the clinic.

Image processing improvements afford second-generation handheld optoacoustic imaging of breast cancer patients

BACKGROUND

Since the initial breast transillumination almost a century ago, breast cancer imaging using light has been considered in different implementations aiming to improve diagnostics, minimize the number of available biopsies, or monitor treatment. However, due to strong photon scattering, conventional optical imaging yields low resolution images, challenging quantification and interpretation. Optoacoustic imaging addresses the scattering limitation and yields high-resolution visualization of optical contrast, offering great potential value for breast cancer imaging. Nevertheless, the image quality of experimental systems remains limited due to a number of factors, including signal attenuation with depth and partial view angle and motion effects, particularly in multi-wavelength measurements.

METHODS

We developed data analytics methods to improve the accuracy of handheld optoacoustic breast cancer imaging, yielding second-generation optoacoustic imaging performance operating in tandem with ultrasonography.

RESULTS

We produced the most advanced images yet with handheld optoacoustic examinations of the human breast and breast cancer, in terms of resolution and contrast. Using these advances, we examined optoacoustic markers of malignancy, including vasculature abnormalities, hypoxia, and inflammation, on images obtained from breast cancer patients.

CONCLUSIONS

We achieved a new level of quality for optoacoustic images from a handheld examination of the human breast, advancing the diagnostic and theranostic potential of the hybrid optoacoustic-ultrasound (OPUS) examination over routine ultrasonography.

Carbonized paramagnetic complexes of Mn (II) as contrast agents for precise magnetic resonance imaging of sub-millimeter-sized orthotopic tumors

Paramagnetic complexes containing gadolinium ions have been widely used for magnetic resonance imaging (MRI) in clinic. However, these paramagnetic complexes pose some safety concerns. There is still a demand for the development of stable MRI contrast agents that exhibit higher sensitivity and superior functionality to existing contrast agents. Here, we develop carbonized paramagnetic complexes of manganese (II) (Mn@CCs) to encapsulate Mn2+ in sealed carbonized shells with superhigh r1 relaxivity. Compared to the most common clinical contrast agent Magnevist, investigations in vivo demonstrate that the Mn@CCs cross the intact blood-brain barrier of normal health mice with minor metal deposition; preferentially target the glioma tissues distribute homogeneously with high penetration in an intracranial mouse model; delineate clear tumor margins in MRIs of ultrasmall single-nodule brain tumors, and multi-nodular liver tumors. The sensitivity, accuracy and low toxicity offer by Mn@CCs provides new opportunities for early molecular diagnostics and imaging-guided biomedical applications.

Molecular Endoscopy for the Diagnosis and Therapeutic Monitoring of Colorectal Cancer

Colorectal cancer (CRC) is one of the leading causes of cancer related death in the western world. Its successful treatment requires early detection and removal of precursor lesions as well as individualized treatment of advanced disease. During recent years, molecular imaging techniques have shown promising results to improve current clinical practice. For instance, molecular endoscopy resulted in higher detection rates of precursors in comparison to conventional endoscopy in preclinical and clinical studies. Molecular confocal endomicroscopy allowed a further classification of suspect lesions as well as the prediction and monitoring of the therapeutic response. In this review, we summarize recent achievements for molecular imaging of CRC in preclinical studies, initial clinical trials and the remaining challenges for future translation into clinical practice.

Enhanced Tumor Imaging Using Glucosamine-Conjugated Polyacrylic Acid-Coated Ultrasmall Gadolinium Oxide Nanoparticles in Magnetic Resonance Imaging

Owing to a higher demand for glucosamine (GlcN) in metabolic processes in tumor cells than in normal cells (i.e., GlcN effects), tumor imaging in magnetic resonance imaging (MRI) can be highly improved using GlcN-conjugated MRI contrast agents. Here, GlcN was conjugated with polyacrylic acid (PAA)-coated ultrasmall gadolinium oxide nanoparticles (UGONs) (davg = 1.76 nm). Higher positive (brighter or T1) contrast enhancements at various organs including tumor site were observed in human brain glioma (U87MG) tumor-bearing mice after the intravenous injection of GlcN-PAA-UGONs into their tail veins, compared with those obtained with PAA-UGONs as control, which were rapidly excreted through the bladder. Importantly, the contrast enhancements of the GlcN-PAA-UGONs with respect to those of the PAA-UGONs were the highest in the tumor site owing to GlcN effects. These results demonstrated that GlcN-PAA-UGONs can serve as excellent T1 MRI contrast agents in tumor imaging via GlcN effects.

A review of surface-enhanced Raman spectroscopy in pathological processes

With the continuous growth of the human population and new challenges in the quality of life, it is more important than ever to diagnose diseases and pathologies with high accuracy, sensitivity and in different scenarios from medical implants to the operation room. Although conventional methods of diagnosis revolutionized healthcare, alternative analytical methods are making their way out of academic labs into clinics. In this regard, surface-enhanced Raman spectroscopy (SERS) developed immensely with its capability to achieve single-molecule sensitivity and high-specificity in the last two decades, and now it is well on its way to join the arsenal of physicians. This review discusses how SERS is becoming an essential tool for the clinical investigation of pathologies including inflammation, infections, necrosis/apoptosis, hypoxia, and tumors. We critically discuss the strategies reported so far in nanoparticle assembly, functionalization, non-metallic substrates, colloidal solutions and how these techniques improve SERS characteristics during pathology diagnoses like sensitivity, selectivity, and detection limit. Moreover, it is crucial to introduce the most recent developments and future perspectives of SERS as a biomedical analytical method. We finally discuss the challenges that remain as bottlenecks for a routine SERS implementation in the medical room from in vitro to in vivo applications. The review showcases the adaptability and versatility of SERS to resolve pathological processes by covering various experimental and analytical methods and the specific spectral features and analysis results achieved by these methods.

Recent Advances in Photosensitizers as Multifunctional Theranostic Agents for Imaging-Guided Photodynamic Therapy of Cancer

In recent years tremendous effort has been invested in the field of cancer diagnosis and treatment with an overall goal of improving cancer management, therapeutic outcome, patient survival, and quality of life. Photodynamic Therapy (PDT), which works on the principle of light-induced activation of photosensitizers (PS) leading to Reactive Oxygen Species (ROS) mediated cancer cell killing has received increased attention as a promising alternative to overcome several limitations of conventional cancer therapies. Compared to conventional therapies, PDT offers the advantages of selectivity, minimal invasiveness, localized treatment, and spatio-temporal control which minimizes the overall therapeutic side effects and can be repeated as needed without interfering with other treatments and inducing treatment resistance. Overall PDT efficacy requires proper planning of various parameters like localization and concentration of PS at the tumor site, light dose, oxygen concentration and heterogeneity of the tumor microenvironment, which can be achieved with advanced imaging techniques. Consequently, there has been tremendous interest in the rationale design of PS formulations to exploit their theranostic potential to unleash the imperative contribution of medical imaging in the context of successful PDT outcomes. Further, recent advances in PS formulations as activatable phototheranostic agents have shown promising potential for finely controlled imaging-guided PDT due to their propensity to specifically turning on diagnostic signals simultaneously with photodynamic effects in response to the tumor-specific stimuli. In this review, we have summarized the recent progress in the development of PS-based multifunctional theranostic agents for biomedical applications in multimodal imaging combined with PDT. We also present the role of different imaging modalities; magnetic resonance, optical, nuclear, acoustic, and photoacoustic in improving the pre-and post-PDT effects. We anticipate that the information presented in this review will encourage future development and design of PSs for improved image-guided PDT for cancer treatment.

Modular Synthesis of Peptide-Based Single- and Multimodal Targeted Molecular Imaging Agents

A practical, modular synthesis of targeted molecular imaging agents (TMIAs) containing near-infrared dyes for optical molecular imaging (OMI) or chelated metals for magnetic resonance imaging (MRI) and single-photon emission correlation tomography (SPECT) or positron emission tomography (PET) has been developed. In the method, imaging modules are formed early in the synthesis by attaching imaging agents to the side chain of protected lysines. These modules may be assembled to provide a given set of single- or dual-modal imaging agents, which may be conjugated in the last steps of the synthesis under mild conditions to linkers and targeting groups. A key discovery was the ability of a metal such as gadolinium, useful in MRI, to serve as a protecting group for the chelator, 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA). It was further discovered that two lanthanide metals, La and Ce, can double as protecting groups and placeholder metals, which may be transmetalated under mild conditions by metals used for PET in the final step. The modular method enabled the synthesis of discrete targeted probes with two of the same or different dyes, two same or different metals, or mixtures of dyes and metals. The approach was exemplified by the synthesis of single- or dual-modal imaging modules for MRI-OMI, PET-OMI, and PET-MRI, followed by conjugation to the integrin-seeking peptide, c(RGDyK). For Gd modules, their efficacy for MRI was verified by measuring the NMR spin-lattice relaxivity. To validate functional imaging of TMIAs, dual-modal agents containing Cy5.5 were shown to target A549 cancer cells by confocal fluorescence microscopy.

Precision Oncology, Signaling and Anticancer Agents in Cancer Therapeutics

BACKGROUND

The global alliance for genomics and healthcare facilities provides innovational solutions to expedite research and clinical practices for complex and incurable health conditions. Precision oncology is an emerging field explicitly tailored to facilitate cancer diagnosis, prevention and treatment based on patients' genetic profile. Advancements in "omics" techniques, next-generation sequencing, artificial intelligence and clinical trial designs provide a platform for assessing the efficacy and safety of combination therapies and diagnostic procedures.

METHOD

Data were collected from Pubmed and Google scholar using keywords: "Precision medicine", "precision medicine and cancer", "anticancer agents in precision medicine" and reviewed comprehensively.

RESULTS

Personalized therapeutics including immunotherapy, cancer vaccines, serve as a groundbreaking solution for cancer treatment. Herein, we take a measurable view of precision therapies and novel diagnostic approaches targeting cancer treatment. The contemporary applications of precision medicine have also been described along with various hurdles identified in the successful establishment of precision therapeutics.

CONCLUSION

This review highlights the key breakthroughs related to immunotherapies, targeted anticancer agents, and target interventions related to cancer signaling mechanisms. The success story of this field in context to drug resistance, safety, patient survival and in improving quality of life is yet to be elucidated. We conclude that, in the near future, the field of individualized treatments may truly revolutionize the nature of cancer patient care.

Sequential SPECT and NIR-II imaging of tumor and sentinel lymph node metastasis for diagnosis and image-guided surgery

Efficacious cancer treatment largely relies on accurate imaging diagnosis and imaging-guided surgery, which can be achieved by combining different mode imaging probes on one single nanoplatform. Herein, a novel radiolabeled NIR-II nanoprobe (¹²⁵I-MT NP) was developed to enable versatile single-photon emission computed tomography (SPECT) and second near-infrared (NIR-II) fluorescence dual-modal imaging against breast cancer. ¹²⁵I-MT was precipitated with an amphiphilic triblock copolymer (PEO-PPO-PEO) to form ¹²⁵I-MT NPs. The ¹²⁵I-MT NPs exhibited high labeling efficiency (98 ± 2%) with a hydrodynamic diameter of 91.3 ± 5.5 nm. In vitro and in vivo studies demonstrated that ¹²⁵I-MT NPs emitted intensive NIR-II fluorescence and SPECT signals, and possessed good biocompatibility. By using a breast tumor xenograft mouse model after intravenous injection of ¹²⁵I-MT NPs, the SPECT imaging and NIR-II imaging showed clear images of tumor tissues at 8 h and 48 h postinjection, respectively, suggesting the feasibility of using ¹²⁵I-MT NPs to detect tumors before surgery and visualize the dissection area during surgery. In addition, the SPECT scan of a lymph node mapping was performed at 1 h postinjection and NIR-II fluorescence imaging was carried out at 4 h postinjection. This further guarantees the accurate imaging of lymph nodes before and during surgery for lymphadenectomy. Overall ¹²⁵I-MT NP is a promising, practical imaging probe for sequential imaging and precision cancer therapy.

Imaging Inflammation with Positron Emission Tomography

The impact of inflammation on the outcome of many medical conditions such as cardiovascular diseases, neurological disorders, infections, cancer, and autoimmune diseases has been widely acknowledged. However, in contrast to neurological, oncologic, and cardiovascular disorders, imaging plays a minor role in research and management of inflammation. Imaging can provide insights into individual and temporospatial biology and grade of inflammation which can be of diagnostic, therapeutic, and prognostic value. There is therefore an urgent need to evaluate and understand current approaches and potential applications for imaging of inflammation. This review discusses radiotracers for positron emission tomography (PET) that have been used to image inflammation in cardiovascular diseases and other inflammatory conditions with a special emphasis on radiotracers that have already been successfully applied in clinical settings.

Bioluminescence Imaging Applications in Cancer: A Comprehensive Review

Bioluminescence imaging (BLI), an optical preclinical imaging modality, is an invaluable imaging modality due to its low-cost, high throughput, fast acquisition times, and functional imaging capabilities. BLI is being extensively used in the field of cancer imaging, especially with the recent developments in genetic-engineering, stem cell, and gene therapy treatments. The purpose of this paper is to provide a comprehensive review of the principles, developments, and current status of BLI in cancer research. This paper covers the fundamental BLI concepts including BLI reporters and enzyme-substrate systems, data acquisition, and image characteristics. It reviews the studies discussing the use of BLI in cancer research such as imaging tumor-characteristic phenomena including tumorigenesis, metastasis, cancer metabolism, apoptosis, hypoxia, and angiogenesis, and response to cancer therapy treatments including chemotherapy, radiotherapy, immunotherapy, gene therapy, and stem cell therapy. The key advantages and disadvantages of BLI compared to other common imaging modalities are also discussed.

DNA Nanostructures and DNA-Functionalized Nanoparticles for Cancer Theranostics

In the last two decades, DNA has attracted significant attention toward the development of materials at the nanoscale for emerging applications due to the unparalleled versatility and programmability of DNA building blocks. DNA-based artificial nanomaterials can be broadly classified into two categories: DNA nanostructures (DNA-NSs) and DNA-functionalized nanoparticles (DNA-NPs). More importantly, their use in nanotheranostics, a field that combines diagnostics with therapy via drug or gene delivery in an all-in-one platform, has been applied extensively in recent years to provide personalized cancer treatments. Conveniently, the ease of attachment of both imaging and therapeutic moieties to DNA-NSs or DNA-NPs enables high biostability, biocompatibility, and drug loading capabilities, and as a consequence, has markedly catalyzed the rapid growth of this field. This review aims to provide an overview of the recent progress of DNA-NSs and DNA-NPs as theranostic agents, the use of DNA-NSs and DNA-NPs as gene and drug delivery platforms, and a perspective on their clinical translation in the realm of oncology.

Manganese-Based Targeted Nanoparticles for Postoperative Gastric Cancer Monitoring via Magnetic Resonance Imaging

Postoperative recurrence is a common and severe problem in the treatment of gastric cancer; consequently, a prolonged course of chemotherapy treatment is inevitable. Monitoring by imaging could provide an accurate evaluation of the therapeutic effects, which would be beneficial to guide a treatment strategy adjustment over time. However, current imaging technologies remain insufficient for the continuous postoperative monitoring of gastric cancer. In this case, molecular imaging offers an efficient strategy. Targetable contrast agents are an essential part of molecular imaging, which could greatly enhance the accuracy and quality of monitoring. Herein, we synthesized a Mn-based contrast agent for magnetic resonance imaging (MRI) of gastric cancer monitoring. Initially, small-sized Mn3O4 nanoparticles (NPs) were synthesized. Then, a functionalized polyethylene glycol (PEG) lipid was attached to the surface of the Mn3O4 NPs, to improve biocompatibility. The targetable MRI contrast agent (Mn3O4@PEG-RGD NPs) was further prepared by the conjugation of the arginine-glycine-aspartic acid (RGD) peptides. The completed Mn3O4@PEG-RGD NPs had the small size of 7.3 ± 2.7 nm and exhibited superior colloidal stability in different solution environments. In addition, Mn3O4@PEG-RGD NPs exhibited reliable biotolerance and low toxicity both in vitro and in vivo. Imaging experiments amply demonstrated that Mn3O4@PEG-RGD NPs could efficiently accumulate in gastric cancer tissues and cells via RGD mediation, and immediately significantly increased the MRI effects. Through this study, we can conclude that Mn3O4@PEG-RGD NPs have the potential to be a novel MRI contrast agent for the postoperative monitoring of gastric cancer.

Magnetic Resonance Imaging for Translational Research in Oncology

The translation of results from the preclinical to the clinical setting is often anything other than straightforward. Indeed, ideas and even very intriguing results obtained at all levels of preclinical research, i.e., in vitro, on animal models, or even in clinical trials, often require much effort to validate, and sometimes, even useful data are lost or are demonstrated to be inapplicable in the clinic. In vivo, small-animal, preclinical imaging uses almost the same technologies in terms of hardware and software settings as for human patients, and hence, might result in a more rapid translation. In this perspective, magnetic resonance imaging might be the most translatable technique, since only in rare cases does it require the use of contrast agents, and when not, sequences developed in the lab can be readily applied to patients, thanks to their non-invasiveness. The wide range of sequences can give much useful information on the anatomy and pathophysiology of oncologic lesions in different body districts. This review aims to underline the versatility of this imaging technique and its various approaches, reporting the latest preclinical studies on thyroid, breast, and prostate cancers, both on small laboratory animals and on human patients, according to our previous and ongoing research lines.

In vitro measurement of glucose uptake after radiation and cetuximab treatment in head and neck cancer cell lines using 18F-FDG, gamma spectrometry and PET/CT

The standard treatment for head and neck squamous cell carcinoma (HNSCC) is radiotherapy, often in combination with chemotherapy or surgery. However, a novel monoclonal antibody, cetuximab (Erbitux^®), has also been approved for patient therapy. The aim of present study was to develop an in vitro method for the measurement of 18F-fluoro-2deoxy-D-glucose (FDG) to determine if cellular 18F-FDG uptake is associated with response to radiotherapy or cetuximab treatment. In the current study, HNSCC cell lines were treated with radiation or with cetuximab. Next, the uptake of 18F-FDG was measured using a gamma spectrometer (GS). Thereafter, uptake after radiation was measured first with GS and then compared with positron emission tomography (PET)/computed tomography (CT) imaging. Furthermore, the mRNA expression of glucose transporter 1 (GLUT1) was measured following cetuximab treatment via reverse transcription-quantitative PCR. A study protocol was developed to measure the cellular uptake of 18F-FDG via gamma-ray spectrometry and comparable results were obtained with those of clinical PET/CT. The results revealed a decrease in 18F-FDG after radiation and cetuximab treatment. The uptake of 18F-FDG following cetuximab treatment was significantly lower in the cetuximab-sensitive cell line UT-SCC-14 compared with the cetuximab-resistant cell lines UT-SCC-2 and UT-SCC-45. Furthermore, after treatment with cetuximab for 24 and 48 h, a significant increase in GLUT1 expression was detected in the sensitive cell line compared with the two resistant cell lines. In conclusion, a novel yet reliable method for the measurement of intracellular 18F-FDG via GS has been developed, and our results indicate that 18F-FDG uptake is associated with radiation and cetuximab response in HNSCC.

In Vivo Imaging-Driven Approaches to Study Virus Dissemination and Pathogenesis

Viruses are causative agents for many diseases and infect all living organisms on the planet. Development of effective therapies has relied on our ability to isolate and culture viruses in vitro, allowing mechanistic studies and strategic interventions. While this reductionist approach is necessary, testing the relevance of in vitro findings often takes a very long time. New developments in imaging technologies are transforming our experimental approach where viral pathogenesis can be studied in vivo at multiple spatial and temporal resolutions. Here, we outline a vision of a top-down approach using noninvasive whole-body imaging as a guide for in-depth characterization of key tissues, physiologically relevant cell types, and pathways of spread to elucidate mechanisms of virus spread and pathogenesis. Tool development toward imaging of infectious diseases is expected to transform clinical diagnosis and treatment.

A literature review on multimodality molecular imaging nanoprobes for cancer detection

Molecular imaging techniques using nanoparticles have significant potential to be widely used for the detection of various types of cancers. Nowadays, there has been an increased focus on developing novel nanoprobes as molecular imaging contrast enhancement agents in nanobiomedicine. The purpose of this review article is to summarize the use of a variety of nanoprobes and their current achievements in accurate cancer imaging and effective treatment. Nanoprobes are rapidly becoming potential tools for cancer diagnosis by using novel molecular imaging modalities such as Ultrasound (US) imaging, Computerized Tomography (CT), Single Photon Emission Tomography (SPECT) and Positron Emission Tomography (PET), Magnetic Resonance Imaging (MRI), and Optical Imaging. These imaging modalities may facilitate earlier and more accurate diagnosis and staging the most of cancers.

Computational Approaches in Theranostics: Mining and Predicting Cancer Data

The ability to understand the complexity of cancer-related data has been prompted by the applications of (1) computer and data sciences, including data mining, predictive analytics, machine learning, and artificial intelligence, and (2) advances in imaging technology and probe development. Computational modelling and simulation are systematic and cost-effective tools able to identify important temporal/spatial patterns (and relationships), characterize distinct molecular features of cancer states, and address other relevant aspects, including tumor detection and heterogeneity, progression and metastasis, and drug resistance. These approaches have provided invaluable insights for improving the experimental design of therapeutic delivery systems and for increasing the translational value of the results obtained from early and preclinical studies. The big question is: Could cancer theranostics be determined and controlled in silico? This review describes the recent progress in the development of computational models and methods used to facilitate research on the molecular basis of cancer and on the respective diagnosis and optimized treatment, with particular emphasis on the design and optimization of theranostic systems. The current role of computational approaches is providing innovative, incremental, and complementary data-driven solutions for the prediction, simplification, and characterization of cancer and intrinsic mechanisms, and to promote new data-intensive, accurate diagnostics and therapeutics.

Breaking the Depth Dependence by Nanotechnology-Enhanced X-Ray-Excited Deep Cancer Theranostics

The advancements in nanotechnology have created multifunctional nanomaterials aimed at enhancing diagnostic accuracy and treatment efficacy for cancer. However, the ability to target deep-seated tumors remains one of the most critical challenges for certain nanomedicine applications. To this end, X-ray-excited theranostic techniques provide a means of overcoming the limits of light penetration and tissue attenuation. Herein, a comprehensive overview of the recent advances in nanotechnology-enhanced X-ray-excited imaging and therapeutic methodologies is presented, with an emphasis on the design of multifunctional nanomaterials for contrast-enhanced computed tomography (CT) imaging, X-ray-excited optical luminescence (XEOL) imaging, and X-ray-excited multimodal synchronous/synergistic therapy. The latter is based on the concurrent use of radiotherapy with chemotherapy, gas therapy, photodynamic therapy, or immunotherapy. Moreover, the featured biomedical applications of X-ray-excited deep theranostics are discussed to highlight the advantages of X-ray in high-sensitivity detection and efficient elimination of malignant tumors. Finally, key issues and technical challenges associated with this deep theranostic technology are identified, with the intention of advancing its translation into the clinic.

Chemical and photonic interactions in vitro and in vivo between fluorescent tracer and nanoparticle-based scavenger for enhanced molecular imaging

We hereby present a concept of scavenging excess imaging agent prior to a diagnostic imaging session, consequently allowing for enhanced contrast of signals originating from the tissue area of interest to the signals originating from systemic imaging agent residues. In our study, a prospective silica core-shell nanoparticle-based scavenger was designed and explored for its feasibility to scavenge a specific imaging agent (tracer) in the bloodstream. The developed tracer-scavenger system was first investigated under in vitro conditions to ensure proper binding between tracer and scavenger is taking place, as confirmed by Förster/fluorescence resonance energy transfer studies. In vivo, two-photon imaging was utilized to directly study the interaction of the scavenger particles and the tracer molecules in the vasculature of mice. To our knowledge, a methodological solution for in vivo differentiation between signals, originating from tissue and blood, has not been presented elsewhere.

DNA aptamers from whole-cell SELEX as new diagnostic agents against glioblastoma multiforme cells

Glioma is a cancer derived from transformed glial cells, which are often invasive and display a heterogeneous cell population. Currently, no trustworthy biomarkers for the detection and risk stratification of glioma have been discovered. The objective of the present research was to select DNA aptamers to facilitate early diagnosis and effective therapy of glioma. Using cell-SELEX, three aptamers (WYZ-37, WYZ-41, WYZ-50), which can specifically recognize the molecular differences between target cells T98G and negative cells SVGp12, were identified. The best binding sequences WYZ-41 and WYZ-50 were optimized in length, resulting in aptamer sequences WYZ-41a and WYZ-50a. The Kd values of the aptamers WYZ-41a and WYZ-50a against the target cell line were found to be 1.0 ± 0.2 nM and 2.8 ± 0.6 nM, respectively, which are better than the Kds for full-length aptamers WYZ-41 and WYZ-50. Flow cytometry analysis results show that the aptamers WYZ-41a and WYZ-50a do not influence each other in mutual binding, and that they effectively detect the target even in complex mixtures, such as undiluted fetal bovine serum (FBS) and cerebral spinal fluid (CSF), indicating that aptamers WYZ-41a and WYZ-50a have excellent potential as aptamer pairs to improve the accuracy of glioma diagnosis.

Optimization of HER3 expression imaging using affibody molecules: Influence of chelator for labeling with indium-111

Radionuclide molecular imaging of human epidermal growth factor receptor 3 (HER3) expression using affibody molecules could be used for patient stratification for HER3-targeted cancer therapeutics. We hypothesized that the properties of HER3-targeting affibody molecules might be improved through modification of the radiometal-chelator complex. Macrocyclic chelators NOTA (1,4,7-triazacyclononane-N,N',N''-triacetic acid), NODAGA (1-(1,3-carboxypropyl)-4,7-carboxymethyl-1,4,7-triazacyclononane), DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid), and DOTAGA (1,4,7,10-tetraazacyclododececane,1-(glutaric acid)-4,7,10-triacetic acid) were conjugated to the C-terminus of anti-HER3 affibody molecule Z08698 and conjugates were labeled with indium-111. All conjugates bound specifically and with picomolar affinity to HER3 in vitro. In mice bearing HER3-expressing xenografts, no significant difference in tumor uptake between the conjugates was observed. Presence of the negatively charged 111In-DOTAGA-complex resulted in the lowest hepatic uptake and the highest tumor-to-liver ratio. In conclusion, the choice of chelator influences the biodistribution of indium-111 labeled anti-HER3 affibody molecules. Hepatic uptake of anti-HER3 affibody molecules could be reduced by the increase of negative charge of the radiometal-chelator complex on the C-terminus without significantly influencing the tumor uptake.

Genomic Interventions in Medicine

Lately, the term "genomics" has become ubiquitous in many scientific articles. It is a rapidly growing aspect of the biomedical sciences that studies the genome. The human genome contains a torrent of information that gives clues about human origin, evolution, biological function, and diseases. In a bid to demystify the workings of the genome, the Human Genome Project (HGP) was initiated in 1990, with the chief goal of sequencing the approximately 3 billion nucleotide base pairs of the human DNA. Since its completion in 2003, the HGP has opened new avenues for the application of genomics in clinical practice. This review attempts to overview some milestone discoveries that paved way for the initiation of the HGP, remarkable revelations from the HGP, and how genomics is influencing a paradigm shift in routine clinical practice. It further highlights the challenges facing the implementation of genomic medicine, particularly in Africa. Possible solutions are also discussed.

Molecular endoscopic imaging in cancer

Cancer is one of the major causes of death in both the USA and Europe. Molecular imaging is a novel field that is revolutionizing cancer management. It is based on the molecular signature of cells in order to study the human body both in normal and diseased conditions. The emergence of molecular imaging has been driven by the difficulties associated with cancer detection, particularly early-stage premalignant lesions which are often unnoticed as a result of minimal or no structural changes. Endoscopic surveillance is the standard method for early-stage cancer detection. In addition to recent major advancements in endoscopic instruments, significant progress has been achieved in the exploration of highly specific molecular probes and the combination of both will permit significant improvement of patient care. In this review, we provide an outline of the current status of endoscopic imaging and focus on recent applications of molecular imaging in gastrointestinal, hepatic and other cancers in the context of detection, targeted therapy and personalized medicine. As new imaging agents have the potential to broadly expand our cancer diagnostic capability, we will also present an overview of the main types of optical molecular probes with their pros and cons. We conclude by discussing the challenges and future prospects of the field.

Characterization of an Orthotopic Colorectal Cancer Mouse Model and Its Feasibility for Accurate Quantification in Positron Emission Tomography

PURPOSE

Quantification in positron emission tomography (PET) imaging of an orthotopic mouse model of colorectal cancer (CRC) is challenging due to difficult tumor delineation. We aimed to establish a reproducible delineation approach, evaluate its feasibility for reliable PET quantification and compare its added translational value with its subcutaneous counterpart.

PROCEDURES

A subcutaneous Colo205-luc2 tumor fragment harvested from a donor mouse was transplanted onto the caecum of nude mice, with (n = 10) or without (n = 10) the addition of an X-ray detectable thread. Animals underwent 2-deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]FDG) PET imaging, complemented with X-ray computed tomography (CT) and magnetic resonance imaging (MRI, 7T). Animals without a thread underwent additional contrast enhanced (Exitron) CT imaging. Tumors were delineated on the MRI, μPET image or contrast enhanced μCT images and correlations between in vivo and ex vivo [¹⁸F]FDG tumor uptake as well as between image-derived and caliper-measured tumor volume were evaluated. Finally, cancer hallmarks were assessed immunohistochemically for the characterization of both models.

RESULTS

Our results showed the strongest correlation between both in vivo and ex vivo uptake (r = 0.84, p < 0.0001) and image-derived and caliper-measured tumor volume (r = 0.96, p < 0.0001) when the tumor was delineated on the MR image. Orthotopic tumors displayed an abundance of stroma, higher levels of proliferation (p = 0.0007), apoptosis (p = 0.02), and necrosis (p < 0.0001), a higher number of blood vessels (p < 0.0001); yet lower tumor hypoxia (p < 0.0001) as compared with subcutaneous tumors.

CONCLUSIONS

This orthotopic mouse model proved to be a promising tool for the investigation of CRC through preclinical imaging studies provided the availability of anatomical MR images for accurate tumor delineation. Furthermore, the tumor microenvironment of the orthotopic tumor resembled more that of human CRC, increasing its likelihood to advance translational nuclear imaging studies of CRC.

Peptide-based nanoprobes for molecular imaging and disease diagnostics

Pathological changes in a diseased site are often accompanied by abnormal activities of various biomolecules in and around the involved cells. Identifying the location and expression levels of these biomolecules could enable early-stage diagnosis of the related disease, the design of an appropriate treatment strategy, and the accurate assessment of the treatment outcomes. Over the past two decades, a great diversity of peptide-based nanoprobes (PBNs) have been developed, aiming to improve the in vitro and in vivo performances of water-soluble molecular probes through engineering of their primary chemical structures as well as the physicochemical properties of their resultant assemblies. In this review, we introduce strategies and approaches adopted for the identification of functional peptides in the context of molecular imaging and disease diagnostics, and then focus our discussion on the design and construction of PBNs capable of navigating through physiological barriers for targeted delivery and improved specificity and sensitivity in recognizing target biomolecules. We highlight the biological and structural roles that low-molecular-weight peptides play in PBN design and provide our perspectives on the future development of PBNs for clinical translation.

Small Molecule PET Tracers in Drug Discovery

The process of discovering and developing a new pharmaceutical is a long, difficult, and risky process that requires numerous resources. Molecular imaging techniques such as PET have recently become a useful tool for making decisions along a drug candidate's development timeline. PET is a translational, noninvasive imaging technique that provides quantitative information about a potential drug candidate and its target at the molecular level. Using this technique provides decisional information to ensure that the right drug candidate is being chosen, for the right target, at the right dose within the right patient population. This review will focus on small molecule PET tracers and how they are used within the drug discovery process. PET provides key information about a drug candidate's pharmacokinetic and pharmacodynamic properties in both preclinical and clinical studies. PET is being used in all phases of the drug discovery and development process, and the goal of these studies are to accelerate the process in which drugs are developed.

Chemistry and engineering of cyclodextrins for molecular imaging

Cyclodextrins (CDs) are naturally occurring cyclic oligosaccharides bearing a basket-shaped topology with an "inner-outer" amphiphilic character. The abundance of hydroxyl groups enables CDs to be functionalized with multiple targeting ligands and imaging elements. The imaging time, and the payload of different imaging elements, can be tuned by taking advantage of the commercial availability of CDs with different sizes of the cavity. This review aims to offer an outlook of the chemistry and engineering of CDs for the development of molecular probes. Complexation thermodynamics of CDs, and the corresponding implications for probe design, are also presented with examples demonstrating the structural and physiochemical roles played by CDs in the full ambit of molecular imaging. We hope that this review not only offers a synopsis of the current development of CD-based molecular probes, but can also facilitate translation of the incremental advancements from the laboratory to real biomedical applications by illuminating opportunities and challenges for future research.

Activatable fluorescent probes in fluorescence-guided surgery: Practical considerations

Fluorescence-guided imaging during surgery is a promising technique that is increasingly used to aid surgeons in identifying sites of tumor and surgical margins. Of the two types of fluorescent probes, always-on and activatable, activatable probes are preferred because they produce higher target-to-background ratios, thus improving sensitivity compared with always-on probes that must contend with considerable background signal. There are two types of activatable probes: 1) enzyme-reactive probes that are normally quenched but can be activated after cleavage by cancer-specific enzymes (activity-based probes) and 2) molecular-binding probes which use cancer targeting moieties such as monoclonal antibodies to target receptors found in abundance on cancers and are activated after internalization and lysosomal processing (binding-based probes). For fluorescence-guided intraoperative surgery, enzyme-reactive probes are superior because they can react quickly, require smaller dosages especially for topical applications, have limited side effects, and have favorable pharmacokinetics. Enzyme-reactive probes are easier to use, fit better into existing work flows in the operating room and have minimal toxicity. Although difficult to prove, it is assumed that the guidance provided to surgeons by these probes results in more effective surgeries with better outcomes for patients. In this review, we compare these two types of activatable fluorescent probes for their ease of use and efficacy.

Can molecular profiling enhance radiotherapy? Impact of personalized targeted gold nanoparticles on radiosensitivity and imaging of adenoid cystic carcinoma

Personalized molecular profiling has an established role in selection of treatment for metastatic disease; however, its role in improving radiosensitivity and functional imaging has not been evaluated. In the current study, we examined molecular profiling as a tool for designing personalized targeted gold nanoparticles (GNP) to serve as dual-modal tumor radiosensitizers and functional imaging enhancers. To this end, molecular profiling of a patient's salivary gland adenoid cystic carcinoma (ACC) was performed, and anaplastic lymphoma kinase (ALK) mutation was detected. The extracted tumor was subcutaneously injected into mice, which were then treated either with radiation, the specific ALK inhibitor crizotinib, or a combination of therapies. One of these combinations, namely, ALK-targeted GNP (via crizotinib coating), was found to enhance radiation treatment, as demonstrated by a significant decrease in tumor volume over 24 days. In parallel, ALK-targeted GNP substantially augmented tumor visualization via computed tomography. The mechanism of radiosensitivity enhancement was mostly related to a diminished cell repair mechanism in tumors, as demonstrated by proliferating cell nuclear antigen staining. These findings indicate that personalized molecular profiling is an effective technique for enhancing cancer theranostics.

Tumor-associated macrophages, nanomedicine and imaging: the axis of success in the future of cancer immunotherapy

The success of any given cancer immunotherapy relies on several key factors. In particular, success hinges on the ability to stimulate the immune system in a controlled and precise fashion, select the best treatment options and appropriate therapeutic agents, and use highly effective tools to accurately and efficiently assess the outcome of the immunotherapeutic intervention. Furthermore, a deep understanding and effective utilization of tumor-associated macrophages (TAMs), nanomedicine and biomedical imaging must be harmonized to improve treatment efficacy. Additionally, a keen appreciation of the dynamic interplay that occurs between immune cells and the tumor microenvironment (TME) is also essential. New advances toward the modulation of the immune TME have led to many novel translational research approaches focusing on the targeting of TAMs, enhanced drug and nucleic acid delivery, and the development of theranostic probes and nanoparticles for clinical trials. In this review, we discuss the key cogitations that influence TME, TAM modulations and immunotherapy in solid tumors as well as the methods and resources of tracking the tumor response. The vast array of current nanomedicine technologies can be readily modified to modulate immune function, target specific cell types, deliver therapeutic payloads and be monitored using several different imaging modalities. This allows for the development of more effective treatments, which can be specifically designed for particular types of cancer or on an individual basis. Our current capacities have allowed for greater use of theranostic probes and multimodal imaging strategies that have led to better image contrast, real-time imaging capabilities leveraging targeting moieties, tracer kinetics and enabling more detailed response profiles at the cellular and molecular levels. These novel capabilities along with new discoveries in cancer biology should drive innovation for improved biomarkers for efficient and individualized cancer therapy.