Plasma protein (albumin) catabolism by the tumor itself--implications for tumor metabolism and the genesis of cachexia

Wolf in Sheep's Clothing: Taming Cancer's Resistance with Human Serum Albumin?

Human serum albumin (HSA) has emerged as a promising carrier for nanodrug delivery, offering unique structural properties that can be engineered to overcome key challenges in cancer treatment, especially resistance to chemotherapy. This review focuses on the cellular uptake of albumin-based nanoparticles and the modifications that enhance their ability to bypass resistance mechanisms, particularly multidrug resistance type 1 (MDR1), by improving targeting to cancer cells. In our unique approach, we integrate the chemical properties of albumin, its interactions with cancer cells, and surface modifications of albumin-based delivery systems that enable to bypass resistance mechanisms, particularly those related to MDR1, and precisely target receptors on cancer cells to improve treatment efficacy. We discuss that while well-established albumin receptors such as gp60 and gp18/30 are crucial for cellular uptake and transcytosis, their biology remains underexplored, limiting their translational potential. Additionally, we explore the potential of emerging targets, such as cluster of differentiation 44 (CD44), cluster of differentiation (CD36) and transferrin receptor TfR1, as well as the advantages of using dimeric forms of albumin (dHSA) to further enhance delivery to resistant cancer cells. Drawing from clinical examples, including the success of albumin-bound paclitaxel (Abraxane) and new formulations like Pazenir and Fyarro (for Sirolimus), we identify gaps in current knowledge and propose strategies to optimize albumin-based systems. In conclusion, albumin-based nanoparticles, when tailored with appropriate modifications, have the potential to bypass multidrug resistance and improve the targeting of cancer cells. By enhancing albumin's ability to efficiently deliver therapeutic agents, these carriers represent a promising approach to addressing one of oncology's most persistent challenges, with substantial potential to improve cancer treatment outcomes.

Applications and enhancement strategies of ROS-based non-invasive therapies in cancer treatment

Reactive oxygen species (ROS) play a crucial role in the pathogenesis of cancer. Non-invasive therapies that promote intracellular ROS generation, including photodynamic therapy (PDT), sonodynamic therapy (SDT), and chemodynamic therapy (CDT), have emerged as novel approaches for cancer treatment. These therapies directly kill tumor cells by generating ROS, and although they show great promise in tumor treatment, many challenges remain to be addressed in practical applications. Firstly, the inherent complexity of the tumor microenvironment (TME), such as hypoxia and elevated glutathione (GSH) levels, hinders ROS generation, thereby significantly diminishing the efficacy of ROS-based therapies. In addition, these therapies are influenced by their intrinsic mechanisms. To overcome these limitations, various nanoparticle (NP) systems have been developed to improve the therapeutic efficacy of non-invasive therapies against tumors. This review first summarizes the mechanisms of ROS generation for each non-invasive therapy and their current limitations, with a particular focus on the enhancement strategies for each therapy based on NP systems. Additionally, various strategies to modulate the TME are highlighted. These strategies aim to amplify ROS generation in non-invasive therapies and enhance their anti-tumor efficiency. Finally, the current challenges and possible solutions for the clinical translation of ROS-based non-invasive therapies are also discussed.

Weight and Blood-Based Markers of Cachexia Predict Disability, Hospitalization and Worse Survival in Cancer Immunotherapy Patients

BACKGROUND

Cancer-associated cachexia can inhibit immune checkpoint inhibitor (ICI) therapy efficacy. Cachexia's effect on ICI therapy has not been studied in large cohorts of cancer patients aside from lung cancer. We studied associations between real-world routinely collected clinical cachexia markers and disability-free, hospitalization-free and overall survival of cancer patients.

METHODS

A retrospective study was conducted of electronic health records (EHR) of patients with lung, renal cell, melanoma and other cancers treated with ICI therapy at Northwestern Medicine of Chicago, IL, United States, between March 2011 and January 2022. Weight, body mass index, absolute neutrophil and lymphocyte counts, albumin and C-reactive protein (CRP) measures were analysed to calculate the Fearon consensus criteria for cachexia, weight loss grading system (WLGS) score, neutrophil-lymphocyte ratio (NLR), Prognostic Nutritional Index (PNI) and modified Glasgow Prognostic Score (mGPS) at ICI therapy initiation. Kaplan-Meier and Cox proportional hazards analyses were used to determine associations between these metrics and disability-free, hospitalization-free and overall survival.

RESULTS

EHR analysis uncovered 3285 cancer patients on ICI therapy (54% > 65 years of age, 50.7% male, 77.7% White). At ICI therapy initiation, 1282 (39.0%) patients had cachexia (consensus criteria), 1641 (50.0%) had a WLGS score ≥ 2, 1806 (55.0%) had an NLR > 3, 1087 (33.1%) had albumin < 3.5 g/dL and 1318 (40.1%) had a PNI < 44. Missing measurements included CRP missing for 98.2% and mGPS missing for 98.6% of patients. Disability-free (n = 1373), hospitalization-free (n = 2374) and overall survival (n = 1599) events were analysed with 1-year rates of 65% (64%-67%), 35% (34%-37%) and 65% (63%-66%), respectively. Multivariate Cox model analyses showed hazard ratios (HR) for cachexia at 1.58 (95% CI 1.38-1.80), 1.47 (95% CI 1.33-1.63) and 1.97 (95% CI 1.75-2.23) for disability, hospitalization and death, respectively. HRs for WLGS ≥ 2 were 1.45 (95% CI 1.28-1.66), 1.37 (95% CI 1.24-1.51) and 1.91 (95% CI 1.69-2.17). HRs for NLR > 3 were 1.57 (95% CI 1.35-1.83), 1.40 (95% CI 1.25-1.58) and 1.95 (95% CI 1.67-2.27). HRs for albumin < 3.5 g/dL were 1.33 (95% CI 1.15-1.54), 1.67 (95% CI 1.50-1.86) and 2.09 (95% CI 1.84-2.36). HRs for PNI < 44 were 1.60 (95% CI 1.39-1.84), 1.46 (95% CI 1.31-1.63) and 2.07 (95% CI 1.80-2.37).

CONCLUSIONS

Fearon consensus criteria, WLGS, NLR, albumin and PNI were routinely collected at ICI initiation in regular clinical practice and predictive of worse disability-free, hospitalization-free and overall survival in cancer patients receiving ICI therapy. These routine clinical measures may aid prognostication and decision-making in cancer patients with cachexia.

Conversion of albumin into a BODIPY-like photosensitizer by a flick reaction, tumor accumulation and photodynamic therapy

The accumulation of photosensitizers (PSs) in lesion sites but not in other organs is an important challenge for efficient image guiding in photodynamic therapy. Cancer cells are known to express a significant number of albumin-binding proteins that take up albumin as a nutrient source. Here, we converted albumin to a novel BODIPY-like PS by generating a tetrahedral boron environment via a flick reaction. The formed albumin PS has almost the same 3-dimensional structural feature as free albumin because binding occurs at Sudlow Site 1, which is located in the interior space of albumin. An i.v. injection experiment in tumor-bearing mice demonstrated that the human serum albumin PS effectively accumulated in cancer tissue and, more surprisingly, albumin PS accumulated much more in the cancer tissue than in the liver and kidneys. The albumin PS was effective at killing tumor cells through the generation of reactive oxygen species under light irradiation. The crystal structure of the albumin PS was fully elucidated by X-ray crystallography; thus, further tuning of the structure will lead to novel physicochemical properties of the albumin PS, suggesting its potential in biological and clinical applications.

A Nanotheranostic Agent for Synergistic Antitumor Chemo/Phototherapy Prepared by Paclitaxel-Induced Self-Assembly of PEGylated Human Serum Albumin with Prolonged Circulation

The integration of different therapies to enhance the efficacy and minimize adverse reactions has become popular recently. This approach leverages the complementary mechanisms of action of different treatments, which can lead to better therapeutic outcomes and reduced side effects. Human serum albumin (HSA) exhibits excellent drug loading ability and is often used for biomimetic tumor delivery in multidrug nanocarriers. However, albumin nanocarriers are often unstable with a short plasma half-life. Therefore, a nanotheranostic agent for synergistic antitumor chemo/phototherapy was designed to improve HSA's pharmacokinetic properties, including prolonged circulation. Cys34-specifically PEGylated HSA (PEG-cys34HSA) was used as the nanocarrier, hydrophobic paclitaxel (PTX) served as the chemotherapeutic drug and self-assembly inducer of nanoparticles (NPs), and near-infrared dye indocyanine green (ICG) was utilized for phototherapy and fluorescence imaging. PEGylation with 20 kDa polyethylene glycol (PEG20kD) promoted the formation of uniform and regular NPs more effectively than PEG5kD. PEG20kD also enhanced the particle size, drug loading, and encapsulation efficiency. Moreover, PEG20kD significantly enhanced tumor targeting without hindering endocytosis, transport, and release of NPs. PEG20kD-cys34HSA/PTX/ICG-mediated combination therapy exhibited synergistic inhibitory effects on tumor growth both in vitro and in vivo. Thus, PEG20kD-cys34HSA shows potential as an alternative nanocarrier. This study provides the foundation for future investigations into PEG-modified nanocarriers and comprehensive tumor treatment.

Drug nanocrystals: Surface engineering and its applications in targeted delivery

Drug nanocrystals have received significant attention in drug development due to their enhanced dissolution rate and improved water solubility, making them effective in overcoming issues related to drug hydrophobicity, thereby improving drug bioavailability and treatment effectiveness. Recent advances in preparation techniques have facilitated research on drug surface properties, leading to valuable surface engineering strategies. Surface modification can stabilize drug nanocrystals, making them suitable for versatile drug delivery platforms. Functionalized ligands further enhance the potential for targeted delivery, enabling precision medicine. This review focuses on the surface engineering of drug nanocrystals, discussing various preparation methods, surface ligand design strategies, and their applications in targeted drug delivery, especially for cancer treatments. Finally, challenges and future directions are also discussed to promote the development of drug nanocrystals. The surface engineering of drug nanocrystals promises new opportunities for treating complex and chronic diseases while broadening the application of drug delivery systems.

Advancing Proteolysis Targeting Chimera (PROTAC) Nanotechnology in Protein Homeostasis Reprograming for Disease Treatment

Proteolysis targeting chimeras (PROTACs) represent a transformative class of therapeutic agents that leverage the intrinsic protein degradation machinery to modulate the hemostasis of key disease-associated proteins selectively. Although several PROTACs have been approved for clinical application, suboptimal therapeutic efficacy and potential adverse side effects remain challenging. Benefiting from the enhanced targeted delivery, reduced systemic toxicity, and improved bioavailability, nanomedicines can be tailored with precision to integrate with PROTACs which hold significant potential to facilitate PROTAC nanomedicines (nano-PROTACs) for clinical translation with enhanced efficacy and reduced side effects. In this review, we provide an overview of the recent progress in the convergence of nanotechnology with PROTAC design, leveraging the inherent properties of nanomaterials, such as lipids, polymers, inorganic nanoparticles, nanohydrogels, proteins, and nucleic acids, for precise PROTAC delivery. Additionally, we discuss the various categories of PROTAC targets and provide insights into their clinical translational potential, alongside the challenges that need to be addressed.

A pan-cancer dye for solid-tumour screening, resection and wound monitoring via short-wave and near-infrared fluorescence imaging

The efficacy of fluorescence-guided surgery in facilitating the real-time delineation of tumours depends on the optical contrast of tumour tissue over healthy tissue. Here we show that CJ215-a commercially available, renally cleared carbocyanine dye sensitive to apoptosis, and with an absorption and emission spectra suitable for near-infrared fluorescence imaging (wavelengths of 650-900 nm) and shortwave infrared (SWIR) fluorescence imaging (900-1,700 nm)-can facilitate fluorescence-guided tumour screening, tumour resection and the assessment of wound healing. In tumour models of either murine or human-derived breast, prostate and colon cancers and of fibrosarcoma, and in a model of intraperitoneal carcinomatosis, imaging of CJ215 with ambient light allowed for the delineation of nearly all tumours within 24 h after intravenous injection of the dye, which was minimally taken up by healthy organs. At later timepoints, CJ215 provided tumour-to-muscle contrast ratios up to 100 and tumour-to-liver contrast ratios up to 18. SWIR fluorescence imaging with the dye also allowed for quantifiable non-contact wound monitoring through commercial bandages. CJ215 may be compatible with existing and emerging clinical solutions.

Impact of breast cancer neoadjuvant chemotherapy on plasma and urine amino acid profile, plasma proteins and nitrogen metabolism

Neoadjuvant chemotherapy (NAC) is the preferred treatment option in locally advanced breast cancer (BC). The administration of NAC is associated with a wide range of adverse effects. This pilot observational prospective study examined the effect of NAC using anthracycline + cyclophosphamide (AC) followed by paclitaxel (PTx) on a portfolio of 22 plasma and urinary amino acids, plasma proteins (albumin, prealbumin, transferrin), and products of nitrogen metabolism (urea, creatinine, uric acid) in plasma and urine. Plasma and 24-h urine samples were obtained from ten patients with early breast cancer (N1-3 N0-2 M0), at the following time points: before the start of NAC and during the AC/PTx treatment period (a total of 8 measurements at three-weekly intervals). Amino acids were analyzed using ion exchange chromatography. There were no significant differences in the measured parameters in plasma and urine between pre-NAC and during AC- and PTx-treatment. No trend was detected. A significant difference in the portfolio of plasma and urinary amino acids was found only in the pre-treatment period compared to the control group. Levels of eight plasma amino acids (8/22) were significantly reduced and those of nine urine amino acids were increased (9/22). Nitrogenous catabolites in plasma and urine were not indicative of increased protein catabolism during the anthracycline and taxane treatment periods. A slightly positive nitrogen balance was accompanied by an average weight gain of 3.3 kg (range 0-6 kg). The AC/PTx treatment regimen did not cause significant changes in the monitored laboratory parameters.

Clinical risk factors for portal hypertension-related complications in systemic therapy for hepatocellular carcinoma

BACKGROUND

During systemic therapy, the management of portal hypertension (PH)-related complications is vital. This study aimed to clarify factors associated with the incidence and exacerbation of PH-related complications, including the usefulness of contrast-enhanced computed tomography (CECT) in the management of PH-related complications during systemic therapy.

METHODS

A total of 669 patients who received systemic therapy as first-line treatment (443 patients for sorafenib, 131 for lenvatinib, and 90 for atezolizumab/bevacizumab [ATZ/BEV]) were enrolled in this retrospective study. Additionally, the lower esophageal intramural vessel diameters (EIV) on CECT and endoscopic findings in 358 patients were compared.

RESULTS

The cutoff values of the EIV diameter on CECT were 3.1 mm for small, 5.1 mm for medium, and 7.6 mm for large varices, demonstrating high concordance with the endoscopic findings. esophageal varices (EV) bleeding predictors include EIV ≥ 3.1 mm and portal vein tumor thrombosis (PVTT). In patients without EV before systemic therapy, factors associated with EV exacerbation after 3 months were EIV ≥ 1.9 mm and ATZ/BEV use. Predictors of hepatic encephalopathy (HE) include the ammonia level or portosystemic shunt diameter ≥ 6.8 mm. The incidence of HE within 2 weeks was significantly higher (18%) in patients with an ammonia level ≥ 73 μmol/L and a portosystemic shunt ≥ 6.8 mm. The exacerbating factors for ascites after 3 months were PVTT and low albumin levels.

CONCLUSIONS

Careful management is warranted for patients with risk factors for exacerbation of PH-related complications; moreover, the effective use of CECT is clinically important.

Design, synthesis, and biological evaluation of cathepsin B cleavage albumin-binding SN38 prodrug in breast cancer

Here, we introduce a novel and effective approach utilizing a cathepsin B cleavage albumin-binding SN38 prodrug specifically designed for the treatment of metastatic breast cancer. Termed Mal-va-mac-SN38, our prodrug exhibits a unique ability to rapidly and covalently bind with endogenous albumin, resulting in the formation of HSA-va-mac-SN38. This prodrug demonstrates exceptional stability in human plasma. Importantly, HSA-va-mac-SN38 showcases an impressive enhancement in cellular uptake by 4T1 breast cancer cells, primarily facilitated through caveolin-mediated endocytosis. Intriguingly, the release of the active SN38, is triggered by the enzymatic activity of cathepsin B within the lysosomal environment. In vivo studies employing a lung metastasis 4T1 breast cancer model underscore the potency of HSA-va-mac-SN38. Histological immunohistochemical analyses further illuminate the multifaceted impact of our prodrug, showcasing elevated levels of apoptosis, downregulated expression of matrix metalloproteinases, and inhibition of angiogenesis, all critical factors contributing to the anti-metastatic effect observed. Biodistribution studies elucidate the capacity of Mal-va-mac-SN38 to augment tumor accumulation through covalent binding to serum albumin, presenting a potential avenue for targeted therapeutic interventions. Collectively, our findings propose a promising therapeutic avenue for metastatic breast cancer, through the utilization of a cathepsin B-cleavable albumin-binding prodrug.

Antibody Drug Clearance: An Underexplored Marker of Outcomes with Checkpoint Inhibitors

Immune-checkpoint inhibitor (ICI) therapy has dramatically changed the clinical landscape for several cancers, and ICI use continues to expand across many cancer types. Low baseline clearance (CL) and/or a large reduction of CL during treatment correlates with better clinical response and longer survival. Similar phenomena have also been reported with other monoclonal antibodies (mAb) in cancer and other diseases, highlighting a characteristic of mAb clinical pharmacology that is potentially shared among various mAbs and diseases. Though tempting to attribute poor outcomes to low drug exposure and arguably low target engagement due to high CL, such speculation is not supported by the relatively flat exposure-response relationship of most ICIs, where a higher dose or exposure is not likely to provide additional benefit. Instead, an elevated and/or increasing CL could be a surrogate marker of the inherent resistant phenotype that cannot be reversed by maximizing drug exposure. The mechanisms connecting ICI clearance, therapeutic efficacy, and resistance are unclear and likely to be multifactorial. Therefore, to explore the potential of ICI CL as an early marker for efficacy, this review highlights the similarities and differences of CL characteristics and CL-response relationships for all FDA-approved ICIs, and we compare and contrast these to selected non-ICI mAbs. We also discuss underlying mechanisms that potentially link mAb CL with efficacy and highlight existing knowledge gaps and future directions where more clinical and preclinical investigations are warranted to clearly understand the value of baseline and/or time-varying CL in predicting response to ICI-based therapeutics.

Structural optimization of siRNA conjugates for albumin binding achieves effective MCL1-directed cancer therapy

The high potential of siRNAs to silence oncogenic drivers remains largely untapped due to the challenges of tumor cell delivery. Here, divalent lipid-conjugated siRNAs are optimized for in situ binding to albumin to improve pharmacokinetics and tumor delivery. Systematic variation of the siRNA conjugate structure reveals that the location of the linker branching site dictates tendency toward albumin association versus self-assembly, while the lipid hydrophobicity and reversibility of albumin binding also contribute to siRNA intracellular delivery. The lead structure increases tumor siRNA accumulation 12-fold in orthotopic triple negative breast cancer (TNBC) tumors over the parent siRNA. This structure achieves approximately 80% silencing of the anti-apoptotic oncogene MCL1 and yields better survival outcomes in three TNBC models than an MCL-1 small molecule inhibitor. These studies provide new structure-function insights on siRNA-lipid conjugate structures that are intravenously injected, associate in situ with serum albumin, and improve pharmacokinetics and tumor treatment efficacy.

Association between preoperative albumin levels and postoperative delirium in geriatric hip fracture patients

Objective

This study aims to examine the association between preoperative serum albumin levels and postoperative delirium (POD) in geriatric patients who have undergone hip fracture surgery, with the goal of offering novel insights for clinical interventions targeting POD.

Methods

A retrospective analysis was conducted on the medical records of patients who underwent hip fracture surgery in a tertiary medical institution from January 2013 to November 2023. The patients were classified based on hypoalbuminemia (defined as a serum albumin level < 35 g/L) and clinical threshold. Multivariable logistic regression and propensity score matching analysis (PSM) were employed to calculate the adjusted odds ratios (OR) and 95% confidence intervals (95% CI) for POD to eliminate potential confounding factors. Additionally, subgroup analysis was performed to explore the interaction effect.

Results

The retrospective cohort study included 1,440 patients, with an incidence of POD found to be 19.1%. In a multivariable logistic regression analysis, patients with hypoalbuminemia had an adjusted OR of 2.99 (95%CI: 2.14-4.18) compared to those with normal albumin levels (≥ 35 g/L). Furthermore, a significant trend was observed across different severity categories, including mild hypoalbuminemia (34.9-30.0 g/L; adjusted OR = 2.71, 95%CI: 1.84-3.99), moderate hypoalbuminemia (29.9-25.0 g/L, adjusted OR = 3.44, 95%CI: 1.88-6.28), and severe hypoalbuminemia (<25.0 g/L; adjusted OR = 3.97, 95%CI: 1.78-8.86), with a trend value of p <0.001. Similar results were observed in the PSM analysis. Additionally, treating preoperative serum albumin level as a continuous variable, the risk of POD increased by 11% (95% CI, 1.08-1.15) with each 1 g/L decrease in preoperative serum albumin level.

Conclusion

Low preoperative levels of albumin are strongly associated with POD in geriatric patients with hip fractures, and a significant dose-response relationship exists between them.

Elevated 18F-FDG uptake in subcutaneous adipose tissue correlates negatively with nutritional status and prognostic survival in cachexia patients with gastric cancer

BACKGROUND

Browning of white adipose tissue is a crucial factor contributing to adipose loss in cachexia patients, detectable via 18F-Fluorodeoxyglucose (18F-FDG) uptake. The present study elucidates the clinical relevance of 18F-FDG uptake in the subcutaneous adipose tissue of gastric cancer patients, specifically focusing on adipose browning and its implications on patient clinical parameters and prognosis.

METHODS

This investigation encompassed 770 gastric cancer patients, with PET-CT imaging and clinical data meticulously combined. The 18F-FDG uptake in subcutaneous adipose tissue at the third lumbar layer was quantified, and its correlation with clinical parameters, particularly those related to nutritional status and fat metabolism, was examined. Kaplan-Meier curves were subsequently employed to probe the relationship between 18F-FDG uptake and overall survival.

RESULTS

Of the 770 gastric cancer patients, 252 exhibited cancer-associated cachexia, while 518 did not. Cachectic patients demonstrated elevated 18F-FDG uptake in subcutaneous adipose tissue relative to non-cachectic patients (P < 0.001). Increased 18F-FDG uptake was also correlated with reduced plasma concentrations of albumin, prealbumin, hemoglobin, platelets, cholesterol, apolipoprotein A, low-density lipoprotein, and elevated IL-6 concentrations (all P < 0.05). A significant inverse correlation was observed between 18F-FDG uptake and BMI, albumin, low-density lipoprotein, cholesterol, and apolipoprotein A (all P < 0.05). Patients with higher 18F-FDG uptake exhibited diminished overall survival rates compared to those with lower 18F-FDG uptake (P = 0.0065). Furthermore, 18F-FDG uptake in subcutaneous adipose tissue was an independent prognostic indicator in gastric cancer patients (P = 0.028).

CONCLUSIONS

Browning of subcutaneous adipose tissue was markedly elevated in cachectic gastric cancer patients compared to non-cachectic counterparts. Increased 18F-FDG uptake in subcutaneous adipose tissue in cachectic gastric cancer patients was inversely correlated with nutritional status and survival prognosis.

Breaking the stromal barrier in pancreatic cancer: Advances and challenges

Pancreatic cancer (PC) remains a leading cause of mortality worldwide due to the absence of early detection methods and the low success rates of traditional therapeutic strategies. Drug resistance in PC is driven by its desmoplastic stroma, which creates a barrier that shields cancer niches and prevents the penetration of drugs. The PC stroma comprises heterogeneous cellular populations and non-cellular components involved in aberrant ECM deposition, immunosuppression, and drug resistance. These components can influence PC development through intricate and complex crosstalk with the PC cells. Understanding how stromal components and cells interact with and influence the invasiveness and refractoriness of PC cells is thus a prerequisite for developing successful stroma-modulating strategies capable of remodeling the PC stroma to alleviate drug resistance and enhance therapeutic outcomes. In this review, we explore how non-cellular and cellular stromal components, including cancer-associated fibroblasts and tumor-associated macrophages, contribute to the immunosuppressive and tumor-promoting effects of the stroma. We also examine the signaling pathways underlying their activation, tumorigenic effects, and interactions with PC cells. Finally, we discuss recent pre-clinical and clinical work aimed at developing and testing novel stroma-modulating agents to alleviate drug resistance and improve therapeutic outcomes in PC.

Metabolic heterogeneity in cancer

Cancer cells rewire their metabolism to survive during cancer progression. In this context, tumour metabolic heterogeneity arises and develops in response to diverse environmental factors. This metabolic heterogeneity contributes to cancer aggressiveness and impacts therapeutic opportunities. In recent years, technical advances allowed direct characterisation of metabolic heterogeneity in tumours. In addition to the metabolic heterogeneity observed in primary tumours, metabolic heterogeneity temporally evolves along with tumour progression. In this Review, we summarize the mechanisms of environment-induced metabolic heterogeneity. In addition, we discuss how cancer metabolism and the key metabolites and enzymes temporally and functionally evolve during the metastatic cascade and treatment.

Exploiting the neonatal crystallizable fragment receptor to treat kidney disease

The neonatal Fc receptor (FcRn) was initially discovered as the receptor that allowed passive immunity in newborns by transporting maternal IgG through the placenta and enterocytes. Since its initial discovery, FcRn has been found to exist throughout all stages of life and in many different cell types. Beyond passive immunity, FcRn is necessary for intrinsic albumin and IgG recycling and is important for antigen processing and presentation. Given its multiple important roles, FcRn has been utilized in many disease treatments including a new class of agents that were developed to inhibit FcRn for treatment of a variety of autoimmune diseases. Certain cell populations within the kidney also express high levels of this receptor. Specifically, podocytes, proximal tubule epithelial cells, and vascular endothelial cells have been found to utilize FcRn. In this review, we summarize what is known about FcRn and its function within the kidney. We also discuss how FcRn has been used for therapeutic benefit, including how newer FcRn inhibiting agents are being used to treat autoimmune diseases. Lastly, we will discuss what renal diseases may respond to FcRn inhibitors and how further work studying FcRn within the kidney may lead to therapies for kidney diseases.

Unraveling the versatility of human serum albumin - A comprehensive review of its biological significance and therapeutic potential

Human serum albumin (HSA) is a multi-domain macromolecule with diverse ligand binding capability because of its ability to allow allosteric modulation despite being a monomeric protein. Physiologically, HSA act as the primary carrier for various exogenous and endogenous compounds and fatty acids, and alter the pharmacokinetic properties of several drugs. It has antioxidant properties and is utilized therapeutically to improve the drug delivery of pharmacological agents for the treatment of several disorders. The flexibility of albumin in holding various types of drugs coupled with a variety of modifications makes this protein a versatile drug carrier with incalculable potential in therapeutics. This review provides a brief outline of the different structural properties of HSA, and its various binding sites, moreover, an overview of the genetic, biomedical, and allosteric modulation of drugs and drug delivery aspects of HSA is also included, which may be helpful in guiding advanced clinical applications and further research on the therapeutic potential of this extraordinary protein.

Unlocking the potential of milk whey protein components in colorectal cancer prevention and therapy

Extensive research from large prospective cohort studies and meta-analytical investigations over recent decades have consistently indicated that dairy foods have protective effects, reducing the risk of colorectal cancer. Most of the literature has explored the potential role of milk minerals and vitamins in managing colorectal cancer. Yet, there is a paucity of a comprehensive summary of the anticancer attributes of milk protein components and their underlying mechanisms of action. Recent advancements have spotlighted the potential of whey proteins, including β-lactoglobulin, α-lactalbumin, serum albumin, and lactoferrin, as promising candidates for both the prevention and treatment of colorectal cancer. Notably, whey proteins have demonstrated a more pronounced capacity for suppressing carcinogen-induced tumors when compared to casein. Their strong binding affinity enables them to serve as effective carriers for small molecules or drugs targeting colon cancer therapy. Furthermore, numerous studies have underscored the anti-inflammatory and antioxidant prowess of whey proteins in cancer prevention. Additionally, whey proteins have been shown to trigger apoptosis, hinder tumor cell proliferation, and impede metastasis. This comprehensive review, therefore, not only substantiates the significance of incorporating whey protein components into a balanced daily diet but also underscores their potential in safeguarding against the onset and progression of colorectal cancer.

Recent Advancements and Strategies for Overcoming the Blood-Brain Barrier Using Albumin-Based Drug Delivery Systems to Treat Brain Cancer, with a Focus on Glioblastoma

Glioblastoma multiforme (GBM) is a highly aggressive malignant tumor, and the most prevalent primary malignant tumor affecting the brain and central nervous system. Recent research indicates that the genetic profile of GBM makes it resistant to drugs and radiation. However, the main obstacle in treating GBM is transporting drugs through the blood-brain barrier (BBB). Albumin is a versatile biomaterial for the synthesis of nanoparticles. The efficiency of albumin-based delivery systems is determined by their ability to improve tumor targeting and accumulation. In this review, we will discuss the prevalence of human glioblastoma and the currently adopted treatment, as well as the structure and some essential functions of the BBB, to transport drugs through this barrier. We will also mention some aspects related to the blood-tumor brain barrier (BTBB) that lead to poor treatment efficacy. The properties and structure of serum albumin were highlighted, such as its role in targeting brain tumors, as well as the progress made until now regarding the techniques for obtaining albumin nanoparticles and their functionalization, in order to overcome the BBB and treat cancer, especially human glioblastoma. The albumin drug delivery nanosystems mentioned in this paper have improved properties and can overcome the BBB to target brain tumors.

Albumin pre-opsonized membrane-active iPep nanomedicine potentiates chemo to immunotherapy of cancer

Chemotherapy-conjugated immunotherapy in clinical oncology conceptually resembles the combined effects of cytoreduction and immunostimulation in membrane targeted cell killings mediated by pore-forming proteins or host defense peptides. Of the similar concept, targeting cancer cell membrane using membrane active peptides is a hopeful therapeutic modality but had long been hindered from in vivo application. Here we report an enabling strategy of pre-opsonizing a membrane penetrating Ir-complexed octa-arginine peptide (iPep) with serum albumin via intrinsic amphipathicity-driven bimodal interactions into nanoparticles (NP). We found that NP triggered stress-mediated 4T1 cell oncosis which induced potent immunological activation, surpassing several well-known immunogenic medicines. Vested with albumin-enhanced in vivo tumor targeting specificity and pharmacokinetic properties, NP showed combined chemo to immunotherapies of s. c. tumors in mice, with decreased percentages of MDSC, Treg, M2-like macrophage and improved infiltration of CTLs in tumor site, caused complete regression of 4T1 and CT26 tumors, outperforming clinical medicines. In a challenging orthotopic breast cancer model, boost i. v. injections of NP acted as in situ tumor vaccine that drastically enhanced 4T1-specific cellular and humoral immunities to reverse disease progression. Thus, with combined effects of direct cytoreduction, immune activation and tumor vaccine, iPep-NP presents the promise and potential of a new modality of cancer medicine.

Evaluation of the Effectiveness of Boron Neutron Capture Therapy with Iodophenyl-Conjugated closo-Dodecaborate on a Rat Brain Tumor Model

High-grade gliomas present a significant challenge in neuro-oncology because of their aggressive nature and resistance to current therapies. Boron neutron capture therapy (BNCT) is a potential treatment method; however, the boron used by the carrier compounds-such as 4-borono-L-phenylalanine (L-BPA)-have limitations. This study evaluated the use of boron-conjugated 4-iodophenylbutanamide (BC-IP), a novel boron compound in BNCT, for the treatment of glioma. Using in vitro drug exposure experiments and in vivo studies, we compared BC-IP and BPA, with a focus on boron uptake and retention characteristics. The results showed that although BC-IP had a lower boron uptake than BPA, it exhibited superior retention. Furthermore, despite lower boron accumulation in tumors, BNCT mediated by BC-IP showed significant survival improvement in glioma-bearing rats compared to controls (not treated animals and neutrons only). These results suggest that BC-IP, with its unique properties, may be an alternative boron carrier for BNCT. Further research is required to optimize this potential treatment modality, which could significantly contribute to advancing the treatment of high-grade gliomas.

Small-Molecule Ferritin Degrader as a Pyroptosis Inducer

Exploring the response of malignant cells to intracellular metabolic stress is critical for understanding pathologic processes and developing anticancer therapies. Herein, we developed ferritin-targeting proteolysis targeting chimeras (PROTACs) to establish the iron excess stress inside cancer cells and investigated subsequent cellular behaviors. We conjugated oleic acid that binds to the ferritin dimer to the ligand of von Hippel-Lindau (VHL) E3 ligase through an alkyl linker. The screened chimera, DeFer-2, degraded ferritin and then rapidly elevated the free iron content, thereby initiating the caspase 3-GSDME-mediated pyroptosis in cancer cells rather than typical ferroptosis that is always associated with iron ion overload. According to its structural and physicochemical characteristics, DeFer-2 was loaded into a tailored albumin-based nano-formulation, which substantially inhibited tumor growth and prolonged the survival time of mice bearing B16F10 subcutaneous tumors with negligible adverse effects. This study developed a ferritin-targeting PROTAC for iron overload stress, revealed iron metabolic dysregulation-mediated pyroptosis, and provided a PROTAC-based pyroptosis inducer for anticancer treatment.

Does Risk of Hyperhomocysteinemia Depend on Thiol-Disulfide Exchange Reactions of Albumin and Homocysteine?

Significance: Increased plasma concentrations of total homocysteine (tHcy; mild-moderate hyperhomocysteinemia: 15-50 μM tHcy) are considered an independent risk factor for the onset/progression of various diseases, but it is not known about how the increase in tHcy causes pathological conditions. Recent Advances: Reduced homocysteine (HSH ∼1% of tHcy) is presumed to be toxic, unlike homocystine (∼9%) and mixed disulfide between homocysteine and albumin (HSS-ALB; homocysteine [Hcy]-albumin mixed disulfide, ∼90%). This and other notions make it difficult to explain the pathogenicity of Hcy because: (i) lowering tHcy does not improve pathological outcomes; (ii) damage due to HSH usually emerges at supraphysiological doses; and (iii) it is not known why tiny increments in plasma concentrations of HSH can be pathological. Critical Issues: Albumin may have a role in Hcy toxicity, because HSS-ALB could release toxic HSH via thiol-disulfide (SH/SS) exchange reactions in cells. Similarly, thiol-disulfide exchange processes of reduced albumin (albumin with free SH group of Cys34 [HS-ALB]) or N-homocysteinylated albumin are plausible alternatives for initiating Hcy pathological events. Adverse effects of albumin and other data reviewed here suggest the hypothesis of a role of albumin in Hcy toxicity. Future Directions: HSS-ALB might be involved in disruption of the antioxidant/oxidant balance in critical tissues (brain, liver, kidney). Since homocysteine-albumin mixed disulfide is a possible intermediate of thiol-disulfide exchange reactions, we suggest that homocysteinylated albumin could be a new pathological factor, and that studies on the redox role of albumin and mixed disulfide production via thiol-disulfide exchange reactions could offer new therapeutic insights for reducing Hcy toxicity.

Recent advancements in fusion protein technologies in oncotherapy: A review

Cancer is a complicated, adaptable, and heterogeneous disease caused by a wide variety of genetic changes that might impair ability of cells to function normally. The majority of the tumors can only be shrunk using conventional oncology therapies like chemotherapy, radiation, and surgical resection, and the tumor often recurs. The inability of conventional cancer therapies to completely destroy the Cancer Stem Cells (CSCs) that otherwise lead to therapy resistance is thus addressed by therapeutic approaches that concentrate on targeting CSCs and their micro-environmental niche. In this review, we summarize approaches that are used for the development of fusion proteins and their therapeutic applications for treating cancer. The main purpose of making advancements towards the fusion technology instead of using conventional treatment methods is to achieve a prolonged half-life of the therapeutic drugs. The fusion of drugs to the immune response enhancing cytokines or the fusion of antibody and cytokines not only increases half-life but also increase the stability of the anti-tumor drug. Several molecules including different fragments of antibodies, cytokines, Human Serum Albumin, transferrin, XTEN polymers, Elastin-like polypeptides (ELPs) can be employed as a fusion partner and the resulting fusion proteins are reported to show enhanced anti-tumor response.

Regulation of protein corona on liposomes using albumin-binding peptide for targeted tumor therapy

Nanocarriers entering the body are usually coated by plasma protein, leading to a protein "corona" easily recognized by tissues and cells. Adjusting the composition of protein coronas may be an efficient way to change the properties and behavior of nanoparticles in vivo. In this study, we modified doxorubicin-loaded liposomes (Lip/DOX) with an albumin-binding domain (ABD) to prepare nanoparticles (ABD-Lip/DOX) that can specifically bind to albumin and form albumin-based protein coronas in vivo for targeted tumor therapy. The prepared liposomes were spherical with a particle size of about 100 nm. After incubating the liposomes with rat serum, the albumin content was eight times higher on ABD-Lip than on control liposomes. ABD-Lip significantly inhibited adsorption of IgG and complement activation in rat serum in vitro, while corona-coated ABD-Lip was internalized to a significantly greater extent than corona-coated control liposomes. In addition, ABD-Lip showed longer blood circulation time, higher tumor accumulation and greater antitumor efficacy than control liposomes in mice bearing 4 T1 tumors, while both liposome formulations showed similar biocompatibility. These results confirm that adjusting the component of protein coronas around nanoparticles can improve their therapeutic efficacy.

Structural Optimization of siRNA Conjugates for Albumin Binding Achieves Effective MCL1-Targeted Cancer Therapy

The high potential for therapeutic application of siRNAs to silence traditionally undruggable oncogenic drivers remains largely untapped due to the challenges of tumor cell delivery. Here, siRNAs were optimized for in situ binding to albumin through C18 lipid modifications to improve pharmacokinetics and tumor delivery. Systematic variation of siRNA conjugates revealed a lead structure with divalent C18 lipids each linked through three repeats of hexaethylene glycol connected by phosphorothioate bonds. Importantly, we discovered that locating the branch site of the divalent lipid structure proximally (adjacent to the RNA) rather than at a more distal site (after the linker segment) promotes association with albumin, while minimizing self-assembly and lipoprotein association. Comparison to higher albumin affinity (diacid) lipid variants and siRNA directly conjugated to albumin underscored the importance of conjugate hydrophobicity and reversibility of albumin binding for siRNA delivery and bioactivity in tumors. The lead conjugate increased tumor siRNA accumulation 12-fold in orthotopic mouse models of triple negative breast cancer over the parent siRNA. When applied for silencing of the anti-apoptotic oncogene MCL-1, this structure achieved approximately 80% MCL1 silencing in orthotopic breast tumors. Furthermore, application of the lead conjugate structure to target MCL1 yielded better survival outcomes in three independent, orthotopic, triple negative breast cancer models than an MCL1 small molecule inhibitor. These studies provide new structure-function insights on optimally leveraging siRNA-lipid conjugate structures that associate in situ with plasma albumin for molecular-targeted cancer therapy.

Protein corona: Friend or foe? Co-opting serum proteins for nanoparticle delivery

For systemically delivered nanoparticles to reach target tissues, they must first circulate long enough to reach the target and extravasate there. A challenge is that the particles end up engaging with serum proteins and undergo immune cell recognition and premature clearance. The serum protein binding, also known as protein corona formation, is difficult to prevent, even with artificial protection via "stealth" coating. Protein corona may be problematic as it can interfere with the interaction of targeting ligands with tissue-specific receptors and abrogate the so-called active targeting process, hence, the efficiency of drug delivery. However, recent studies show that serum protein binding to circulating nanoparticles may be actively exploited to enhance their downstream delivery. This review summarizes known issues of protein corona and traditional strategies to control the corona, such as avoiding or overriding its formation, as well as emerging efforts to enhance drug delivery to target organs via nanoparticles. It concludes with a discussion of prevailing challenges in exploiting protein corona for nanoparticle development.

Modified norcyanines enable ratiometric pH imaging beyond 1000 nm

Activatable fluorophores with emission beyond 1000 nm have the potential to enable high contrast imaging in complex in vivo settings. However, there are few scaffolds that can be applied to this challenge. Here we detail the synthesis and evaluation of benzo[c,d]indole-substituted norcyanines that enable pH responsive fluorescence imaging in the long wavelength (>1150 nm) range. A key component of our molecular design is the installation of a hydrophilic substituted quaternary amine in the central dihydropyridine ring system. A compound with a C4'-phenyl substituent, but not the C4'-protio homologue, exhibits absorbance maxima of 740 nm and 1130 nm in basic and acidic media, respectively, with evidence of J-aggregate-like properties. These two distinct absorbances enabled ratiometric imaging of probe internalization in a tumor model. Overall, these studies provide a new class of activatable long-wavelength responsive fluorophores with promising photophysical properties.

Films, Gels and Electrospun Fibers from Serum Albumin Globular Protein for Medical Device Coating, Biomolecule Delivery and Regenerative Engineering

Albumin is a natural biomaterial that is abundantly available in blood and body fluids. It is clinically used as a plasma expander, thereby increasing the plasma thiol concentration due to its cysteine residues. Albumin is a regulator of intervascular oncotic pressure, serves as an anti-inflammatory modulator, and it has a buffering role due to its histidine imidazole residues. Because of its unique biological and physical properties, albumin has also emerged as a suitable biomaterial for coating implantable devices, for cell and drug delivery, and as a scaffold for tissue engineering and regenerative medicine. As a biomaterial, albumin can be used as surface-modifying film or processed either as cross-linked protein gels or as electrospun fibers. Herein we have discussed how albumin protein can be utilized in regenerative medicine as a hydrogel and as a fibrous mat for a diverse role in successfully delivering drugs, genes, and cells to targeted tissues and organs. The review of prior studies indicated that albumin is a tunable biomaterial from which different types of scaffolds with mechanical properties adjustable for various biomedical applications can be fabricated. Based on the progress made to date, we concluded that albumin-based device coatings, delivery of drugs, genes, and cells are promising strategies in regenerative and personalized medicine.

Lysosomal enzyme trafficking factor LYSET enables nutritional usage of extracellular proteins

Mammalian cells can generate amino acids through macropinocytosis and lysosomal breakdown of extracellular proteins, which is exploited by cancer cells to grow in nutrient-poor tumors. Here, through genetic screens in defined nutrient conditions we characterized LYSET, a transmembrane protein (TMEM251) selectively required when cells consume extracellular proteins. LYSET was found to associate in the Golgi with GlcNAc-1-phosphotransferase, which targets catabolic enzymes to lysosomes through mannose-6-phosphate modification. Without LYSET, GlcNAc-1-phosphotransferase was unstable owing to a hydrophilic transmembrane domain. Consequently, LYSET-deficient cells were depleted of lysosomal enzymes and impaired in turnover of macropinocytic and autophagic cargoes. Thus, LYSET represents a core component of the lysosomal enzyme trafficking pathway, underlies the pathomechanism for hereditary lysosomal storage disorders, and may represent a target to suppress metabolic adaptations in cancer.

Mitotane Nanocarriers for the Treatment of Adrenocortical Carcinoma: Evaluation of Albumin-Stabilized Nanoparticles and Liposomes in a Preclinical In Vitro Study with 3D Spheroids

Adrenocortical carcinoma (ACC) is a heterogeneous malignancy related to poor prognosis and limited treatment options. The orphan drug mitotane (MT) is still a cornerstone in ACC therapy, however, its application is characterized by low aqueous solubility, poor bioavailability, and unfavorable pharmacokinetics, often resulting in below-target plasma concentrations or toxic side effects. Throughout the last decades, nanoparticulate formulations have become attractive carriers to improve anticancer therapy. In this study, injectable MT liposomes (DOPC-MT) and albumin-stabilized MT nanoparticles (BSA-MT) were investigated in depth with respect to their physicochemical properties, and their colloidal and therapeutical stability upon storage. Furthermore, in vitro cytotoxicity was evaluated using the ACC model cell line NCI-H295R for preparing multicellular tumor spheroids, and was compared to non-malignant human dermal fibroblasts. Our results clearly demonstrate that BSA-MT, unlike DOPC-MT, represents a stable and storable MT formulation with a high drug concentration in an aqueous medium. Dual centrifugation was established as a reproducible method for nanoparticle preparation. Although an efficient cytotoxic effect on ACC tumor spheroids was demonstrated, concomitant low toxicity to fibroblasts suggests that higher drug concentrations may be tolerated in vivo. Consequently, BSA-MT is a novel and promising therapeutical approach to address key challenges in MT treatment.

Direct control of lysosomal catabolic activity by mTORC1 through regulation of V-ATPase assembly

Mammalian cells can acquire exogenous amino acids through endocytosis and lysosomal catabolism of extracellular proteins. In amino acid-replete environments, nutritional utilization of extracellular proteins is suppressed by the amino acid sensor mechanistic target of rapamycin complex 1 (mTORC1) through an unknown process. Here, we show that mTORC1 blocks lysosomal degradation of extracellular proteins by suppressing V-ATPase-mediated acidification of lysosomes. When mTORC1 is active, peripheral V-ATPase V₁ domains reside in the cytosol where they are stabilized by association with the chaperonin TRiC. Consequently, most lysosomes display low catabolic activity. When mTORC1 activity declines, V-ATPase V₁ domains move to membrane-integral V-ATPase V_o domains at lysosomes to assemble active proton pumps. The resulting drop in luminal pH increases protease activity and degradation of protein contents throughout the lysosomal population. These results uncover a principle by which cells rapidly respond to changes in their nutrient environment by mobilizing the latent catabolic capacity of lysosomes.

mTORC1 blocks lysosomal nutrient generation. Here, the authors show that mTORC1 inactivation triggers V-ATPase assembly, which rapidly initiates lysosomal acidification and degradation of protein contents throughout the lysosomal population.

Tandem fusion of albumin-binding domains promoted soluble expression and stability of recombinant trichosanthin in vitro and in vivo

Trichosanthin (TCS), as a type 1 ribosome-inactivating protein, has a very high cytoplasmic activity in vitro and can quickly kill cancer cells. However, it is easily filtered and cleared by the kidney, which results in the short half-life and severely limits its application. In this study, we constructed several recombinant proteins by fusing the albumin binding domain mutant ABD035(abbreviated as ABD) to the N- or C-terminus of TCS to endow the recombinant TCS fusion protein with a longer half-life property binding with endogenous human serum albumin (HSA) via ABD to effectively exert its anti-tumor activity in vivo. Pull down, Dynamic light scattering and ELISA assays all showed that TCS fused with two ABD sequences at the C-terminus of TCS, has stronger binding capacity to HSA in vitro than TCS with one ABD. In vivo studies in BALB/C mice were performed and the elimination half-life of TCS-ABD-ABD is about 15-fold longer compared to TCS and anti-tumor activity is about 30% higher than that of TCS alone in BALB/C mouse experiments. Moreover, we found that TCS with two ABDs in tandem have the highest soluble expression level, more than 5 times higher than that of TCS, and the yield of purified protein of TCS-ABD-ABD was as high as 68.9 mg/L culture solution, which was about 7-fold higher than that of TCS. Furthermore, MTT assay showed that the anti-tumor activity of TCS-ABD-ABD was significantly higher than TCS fused with only one ABD sequence, indicating that the repeated ABD sequences facilitated the biological activity of TCS. In this paper, the fusion of the albumin-binding domain in tandem with TCS can effectively improve its stability in vivo and also significantly increase its soluble expression, expanding the application of the albumin-binding domain in the high soluble expression and stability of protein drugs.

Development of S4A-BSA-Au NPs for enhanced anti-tumor therapy of canine breast cancer

S4A ((1R,2R,3S)-1,2-propanediol acetal-zeylenone) is one of the derivatives of zeylenone and exhibits superior cytotoxicity against the canine breast cancer cell line CIPp. However, its poor aqueous solubility and toxicity to normal tissue limit its clinical application. Therefore, in order to enhance the anticancer effect of S4A, in this article, BSA/BSA-Au-nanocluster-aggregated core/shell nanoparticles (B-BANC-NPs) were prepared by using bovine serum albumin (BSA) and HAuCl4, and then we further synthesized S4A-BSA-Au NPs which were spherical, with a diameter of about 60 nm. In vitro cytotoxicity assessed by using CCK-8 assay demonstrated that the IC50 value of the S4A-BSA-Au NPs was 10.39 μg mL-1, which was not significantly different from that of S4A (10.45 μg mL-1). In vitro apoptosis assay showed that the apoptosis rate of cells treated with S4A-BSA-Au NPs was 20.12%, which was significantly higher than that of the control group treated with S4A (11.3%). Notably, S4A-BSA-Au NPs were shown to effectively accumulate at tumor sites with fluorescence tracing. Besides, the effect of S4A-BSA-Au NPs on SPARC expression was determined by western blotting, and the result showed that 24 h after applying S4A-BSA-Au NPs, SPARC expression in low, middle and high dosage groups was lower than that of the control group, and the tendency showed dose dependence. The results revealed that S4A-BSA-Au NPs could effectively improve the anti-tumor activity of S4A on canine breast cancer, which may be associated with their abilities to effectively accumulate within tumor and to reduce the expression of SPARC.

Emerging Albumin-Binding Anticancer Drugs for Tumor-Targeted Drug Delivery: Current Understandings and Clinical Translation

Albumin has shown remarkable promise as a natural drug carrier by improving pharmacokinetic (PK) profiles of anticancer drugs for tumor-targeted delivery. The exogenous or endogenous albumin enhances the circulatory half-lives of anticancer drugs and passively target the tumors by the enhanced permeability and retention (EPR) effect. Thus, the albumin-based drug delivery leads to a potent antitumor efficacy in various preclinical models, and several candidates have been evaluated clinically. The most successful example is Abraxane, an exogenous human serum albumin (HSA)-bound paclitaxel formulation approved by the FDA and used to treat locally advanced or metastatic tumors. However, additional clinical translation of exogenous albumin formulations has not been approved to date because of their unexpectedly low delivery efficiency, which can increase the risk of systemic toxicity. To overcome these limitations, several prodrugs binding endogenous albumin covalently have been investigated owing to distinct advantages for a safe and more effective drug delivery. In this review, we give account of the different albumin-based drug delivery systems, from laboratory investigations to clinical applications, and their potential challenges, and the outlook for clinical translation is discussed. In addition, recent advances and progress of albumin-binding drugs to move more closely to the clinical settings are outlined.

Hypoxia-induced macropinocytosis represents a metabolic route for liver cancer

Hepatocellular carcinoma (HCC) invariably exhibits inadequate O₂ (hypoxia) and nutrient supply. Hypoxia-inducible factor (HIF) mediates cascades of molecular events that enable cancer cells to adapt and propagate. Macropinocytosis is an endocytic process initiated by membrane ruffling, causing the engulfment of extracellular fluids (proteins), protein digestion and subsequent incorporation into the biomass. We show that macropinocytosis occurs universally in HCC under hypoxia. HIF-1 activates the transcription of a membrane ruffling protein, EH domain-containing protein 2 (EHD2), to initiate macropinocytosis. Knockout of HIF-1 or EHD2 represses hypoxia-induced macropinocytosis and prevents hypoxic HCC cells from scavenging protein that support cell growth. Germline or somatic deletion of Ehd2 suppresses macropinocytosis and HCC development in mice. Intriguingly, EHD2 is overexpressed in HCC. Consistently, HIF-1 or macropinocytosis inhibitor suppresses macropinocytosis and HCC development. Thus, we show that hypoxia induces macropinocytosis through the HIF/EHD2 pathway in HCC cells, harnessing extracellular protein as a nutrient to survive.

Cancer cells rely on macropinocytosis to scavenge extracellular proteins for growth. Here the authors show that macropinocytosis supports the survival of hypoxic hepatocellular carcinoma cells and this is dependent on HIF-1, which in turns activates the transcription of a membrane ruffling protein, EH domain-containing protein 2.

Recent advances in nanomedicines for photodynamic therapy (PDT)-driven cancer immunotherapy

Cancer immunotherapy has made tremendous clinical progress in advanced-stage malignancies. However, patients with various tumors exhibit a low response rate to immunotherapy because of a powerful immunosuppressive tumor microenvironment (TME) and insufficient immunogenicity of tumors. Photodynamic therapy (PDT) can not only directly kill tumor cells, but also elicit immunogenic cell death (ICD), providing antitumor immunity. Unfortunately, limitations from the inherent nature and complex TME significantly reduce the efficiency of PDT. Recently, smart nanomedicine-based strategies could subtly modulate the pharmacokinetics of therapeutic compounds and the TME to optimize both PDT and immunotherapy, resulting in an improved antitumor effect. Here, the emerging nanomedicines for PDT-driven cancer immunotherapy are reviewed, including hypoxia-reversed nanomedicines, nanosized metal-organic frameworks, and subcellular targeted nanoparticles (NPs). Moreover, we highlight the synergistic nanotherapeutics used to amplify immune responses combined with immunotherapy against tumors. Lastly, the challenges and future expectations in the field of PDT-driven cancer immunotherapy are discussed.

A carrier free delivery system of a monoacylglycerol lipase hydrophobic inhibitor

Monoacylglycerol lipase (MAGL) is an emerging therapeutic target for cancer. It is involved in lipid metabolism and its inhibition impairs many hallmarks of cancer including cell proliferation, migration/invasion and tumor growth. For these reasons, our group has recently developed a potent reversible MAGL inhibitor (MAGL23), which showed promising anticancer activities. Here in, to improve its pharmacological properties, a nanoformulation based on nanocrystals coated with albumin was prepared for therapeutic applications. MAGL23 was solubilized by a nanocrystallization method with Pluronic F-127 as surfactant into an organic solvent and was recovered as nanocrystals in water after solvent evaporation. Finally, the solubilized nanocrystals were stabilized by human serum albumin to create a smart delivery carrier. An in-silico prediction (lipophilicity, structure at different pH and solubility in water), as well as experimental studies (solubility), have been performed to check the chemical properties of the inhibitor and nanocrystals. The solubility in water increases from less than 0.01 mg/mL (0.0008 mg/mL, predicted) up to 0.82 mg/mL in water. The formulated inhibitor maintained its potency in ovarian and colon cancer cell lines as the free drug. Furthermore, the system was thoroughly observed at each step of the solubilization process till the final formulation stage by different spectroscopic techniques and a comparative study was performed to check the effects of Pluronic F-127 and CTAB as surfactants. The formulated system is favorable to release the drug at physiological pH conditions (at pH 7.4, after 24 h, less than 20% of compound is released). In vivo studies have shown that albumin-complexed nanocrystals increase the therapeutic window of MAGL23 along with a favorable biodistribution. As per our knowledge, we are reporting the first ever nanoformulation of a MAGL inhibitor, which is promising as a therapeutic system where the MAGL enzyme is involved, especially for cancer therapeutic applications.

Systematic Review of Cancer Targeting by Nanoparticles Revealed a Global Association between Accumulation in Tumors and Spleen

Active targeting of nanoparticles toward tumors is one of the most rapidly developing topics in nanomedicine. Typically, this strategy involves the addition of cancer-targeting biomolecules to nanoparticles, and studies on this topic have mainly focused on the localization of such formulations in tumors. Here, the analysis of the factors determining efficient nanoparticle targeting and therapy, various parameters such as types of targeting molecules, nanoparticle type, size, zeta potential, dose, and the circulation time are given. In addition, the important aspects such as how active targeting of nanoparticles alters biodistribution and how non-specific organ uptake influences tumor accumulation of the targeted nanoformulations are discussed. The analysis reveals that an increase in tumor accumulation of targeted nanoparticles is accompanied by a decrease in their uptake by the spleen. There is no association between targeting-induced changes of nanoparticle concentrations in tumors and other organs. The correlation between uptake in tumors and depletion in the spleen is significant for mice with intact immune systems in contrast to nude mice. Noticeably, modulation of splenic and tumor accumulation depends on the targeting molecules and nanoparticle type. The median survival increases with the targeting-induced nanoparticle accumulation in tumors; moreover, combinatorial targeting of nanoparticle drugs demonstrates higher treatment efficiencies. Results of the comprehensive analysis show optimal strategies to enhance the efficiency of actively targeted nanoparticle-based medicines.

Systematic interaction of plasma albumin with the efficacy of chemotherapeutic drugs

Albumin, as the most abundant plasma protein, plays an integral role in the transport of a variety of exogenous and endogenous ligands in the bloodstream and extravascular spaces. For exogenous drugs, especially chemotherapeutic drugs, binding to and being delivered by albumin can significantly affect their efficacy. Meanwhile, albumin can also bind to many endogenous ligands, such as fatty acids, with important physiological significance that can affect tumor proliferation and metabolism. In this review, we summarize how albumin with unique properties affects chemotherapeutic drugs efficacy from the aspects of drug outcome in blood, toxicity, tumor accumulation and direct or indirect interactions with fatty acids, plus application of albumin-based carriers for anti-tumor drug delivery.

Proteomic Research on the Antitumor Properties of Medicinal Mushrooms

Medicinal mushrooms are increasingly being recognized as an important therapeutic modality in complementary oncology. Until now, more than 800 mushroom species have been known to possess significant pharmacological properties, of which antitumor and immunomodulatory properties have been the most researched. Besides a number of medicinal mushroom preparations being used as dietary supplements and nutraceuticals, several isolates from mushrooms have been used as official antitumor drugs in clinical settings for several decades. Various proteomic approaches allow for the identification of a large number of differentially regulated proteins serendipitously, thereby providing an important platform for a discovery of new potential therapeutic targets and approaches as well as biomarkers of malignant disease. This review is focused on the current state of proteomic research into antitumor mechanisms of some of the most researched medicinal mushroom species, including Phellinus linteus, Ganoderma lucidum, Auricularia auricula, Agrocybe aegerita, Grifola frondosa, and Lentinus edodes, as whole body extracts or various isolates, as well as of complex extract mixtures.

Chondroitin sulfate-mediated albumin corona nanoparticles for the treatment of breast cancer

Chondroitin sulfate-mediated albumin corona nanoparticles were readily prepared without any chemical reaction, and their active tumor targeting and therapeutic effects were examined. Negatively charged chondroitin sulfate (CS) and positively charged doxorubicin (DOX) self-assembled into nanoparticles (CS-DOX-NPs) via electrostatic interactions. Bovine serum albumin (BSA) was then adsorbed on the surface of CS-DOX-NPs to form albumin corona nanoparticles (BC-DOX-NPs) protected from endogenous proteins. Due to the dual effect of BSA and CS, BC-DOX-NPs interacted with the gp60, SPARC and CD44 receptors on tumor cells, facilitating their rapid and efficient transcytosis and improving their accumulation and uptake within tumor tissues. The simultaneous presence of BSA and CS also allowed BC-DOX-NPs to target CD44 efficiently, leading to greater cellular uptake and cytotoxicity against 4T1 cells than CS-DOX-NPs or free DOX. Intravenous injection of BC-DOX-NPs into orthotopic 4T1 tumor-bearing mice led to greater drug accumulation at the tumor site than with CS-DOX-NPs or free DOX, resulting in significant inhibition of tumor growth and lower exposure of major organs to the drug.

Carfilzomib and Paclitaxel Co-Loaded Protein Nanoparticles an Effective Therapy Against Pancreatic Adenocarcinomas

Purpose

Therapeutic efficacy of pancreatic adenocarcinomas (PACs) with combined therapy of carfilzomib (CFZ) and paclitaxel (PTX) co-loaded in human serum albumin (HSA) nanoparticles (NPs) was examined.

Methods

CFZ and PTX were encapsulated individually or combined into HSA NPs by a simple reverse self-assembly method developed to achieve an optimal combination ratio for synergistic therapy. CFZ or/and PTX loaded HSA nanoparticles were physically characterized and the evaluation of combination index, drug release, pharmacokinetic, anti-tumor, and biodistribution studies were conducted.

Results

All resultant drug-loaded HSA NPs were spherical with a particle size of <150 nm and a zeta potential of −21.1~−23.0 mV. Drug loading rates and entrapment efficiencies were 9.1%~10.1% and 90.7%~97.1%, respectively. CFZ and PTX demonstrated synergistic effects in an MIA PaCa-2 cytotoxicity at a 1:2 ratio (CI₅₀ were 0.01~0.25). In vitro dissolution revealed that the CFZ/PTX ratio released from the co-loaded HSA NPs (CFZ/PTX/HSA NPs) was about 1.77~2.08, which conformed to the designated loaded ratio. In vivo evaluation showed that the combined therapy of CFZ and PTX at a 1:2 ratio co-loaded in HSA NPs (CFZ/PTX/HSA NPs) demonstrated optimal synergistic improvement of the growth inhibition of MIA PaCa-2 cells with less systematic toxicity, even though the pharmacokinetic profiles observed did not show obvious beneficial and their biodistributions in tumors were found to be smaller.

Conclusion

The one-pot reverse assembly method developed was environmentally friendly and capable of co-loading an optimal combination ratio of two chemodrugs into HSA NPs for synergistic therapy.

Methoxypolyethylene Glycol-Substituted Zinc Phthalocyanines for Multiple Tumor-Selective Fluorescence Imaging and Photodynamic Therapy

Highly tumor-tissue-selective drugs are a prerequisite for accurate diagnosis and efficient photodynamic therapy (PDT) of tumors, but the currently used fluorescent dyes and photosensitizers generally lack the ability for high accumulation and precise localization in tumor tissues. Here we report that monomethoxy polyethylene glycol (MPEG)-modified zinc phthalocyanine (ZnPc) can be selectively accumulated in multiple tumor tissues, and that the selectivity is controlled by the chain length of MPEG. MPEG-monosubstituted ZnPcs with different chain lengths were synthesized, among which the shorter chain (mw < 2k)-modified ZnPc did not show tumor tissue selectivity, while MPEG2k-5k-substituted ZnPc could be rapidly and selectively accumulated in H22 tumor tissues in mice after intravenous injection. Especially, MPEG4k-Pc showed the best tumor tissue selectivity with a tumor/liver (T/L) ratio of 1.7-2.2 in HepG2, MDA-MB231, AGS, and HT-29 tumor-bearing mice. It also exhibited potent photodynamic therapy effects after one PDT treatment, and tumor growth was significantly inhibited in H22-bearing mice with an inhibition rate over 98% and no obvious toxicity. Consequently, MPEG-modified ZnPc could serve as a potential platform for selective fluorescence imaging and photodynamic therapy of multiple tumors.