PEGPH20, a PEGylated human hyaluronidase, induces radiosensitization by reoxygenation in pancreatic cancer xenografts. A molecular imaging study

Recent Advances and Challenges in the Treatment of Advanced Pancreatic Cancer: An Update on Completed and Ongoing Clinical Trials

Pancreatic cancer is a deadly disease with a low survival rate, particularly in its advanced stages. Advanced pancreatic cancer remains a major clinical challenge due to limited treatment options. Surgical resection may not always be feasible, and traditional chemotherapy often shows restricted effectiveness. As a result, researchers are exploring a multifaceted therapeutic approach targeting the genetic and molecular drivers of the disease. A combination of molecular profiling and targeted therapies are being investigated to improve outcomes and address the shortcomings of traditional treatments. The focus of this review is to provide a summary of current and completed clinical trials for the treatment of advanced pancreatic cancer. This includes adagrasib (a KRAS inhibitor), olaparib (a PARP inhibitor for BRCA mutations), APG-1387 (an IAP antagonist), minnelide (an anti-stromal agent), arimastat (an MMP inhibitor), MK-0646 (an IGF1R inhibitor), sirolimus (an mTOR inhibitor), and metabolic inhibitors. These agents are being evaluated both as standalone treatments and in combination with standard therapy. Furthermore, we have summarized novel approaches such as cancer vaccines and ablation techniques as emerging strategies in the treatment of advanced pancreatic cancer. We have also examined the challenges in treating advanced pancreatic cancer and the factors contributing to therapeutic failure, which may offer valuable insights for developing more effective treatment strategies and innovative drug designs.

Polysaccharides as therapeutic vehicles in pancreatic cancer

Pancreatic cancer (PC) is highly aggressive, with rising incidence and mortality rates. It has significant therapy obstacles due to the limited clinical options, late-stage identification, dense tumor microenvironment (TME), and resistance to therapy. Recent advances might improve treatment consequences in therapy strategies that target important TME components. Moreover, new polymeric drug delivery techniques based on polysaccharides such as polymeric micelles, liposomes, and nanoparticles enhance the solubility of drugs, drug stability, and tumor-specific targeting, which increase the chances of circumventing resistance and improving the efficacy of treatment. Preclinical research has suggested that by modulating the TME and enhancing the efficacy of chemotherapy, polysaccharide-based therapy, such as RP02-1 and DPLL-functionalized amylose, may help treat PC.

Targeting Triple NK Cell Suppression Mechanisms: A Comprehensive Review of Biomarkers in Pancreatic Cancer Therapy

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer with poor outcomes due to frequent recurrence, metastasis, and resistance to treatment. A major contributor to this resistance is the tumor's ability to suppress natural killer (NK) cells, which are key players in the immune system's fight against cancer. In PDAC, the tumor microenvironment (TME) creates conditions that impair NK cell function, including reduced proliferation, weakened cytotoxicity, and limited tumor infiltration. This review examines how interactions between tumor-derived factors, NK cells, and the TME contribute to tumor progression and treatment resistance. To address these challenges, we propose a new "Triple NK Cell Biomarker Approach". This strategy focuses on identifying biomarkers from three critical areas: tumor characteristics, TME factors, and NK cell suppression mechanisms. This approach could guide personalized treatments to enhance NK cell activity. Additionally, we highlight the potential of combining NK cell-based therapies with conventional treatments and repurposed drugs to improve outcomes for PDAC patients. While progress has been made, more research is needed to better understand NK cell dysfunction and develop effective therapies to overcome these barriers.

Enhancing Neoadjuvant Virotherapy's Effectiveness by Targeting Stroma to Improve Resectability in Pancreatic Cancer

About one-fourth of patients with pancreatic ductal adenocarcinoma (PDAC) are categorized as borderline resectable (BR) or locally advanced (LA). Chemotherapy and radiation therapy have not yielded the anticipated outcomes in curing patients with BR/LA PDAC. The surgical resection of these tumors presents challenges owing to the unpredictability of the resection margin, involvement of vasculature with the tumor, the likelihood of occult metastasis, a higher ratio of positive lymph nodes, and the relatively larger size of tumor nodules. Oncolytic virotherapy has shown promising activity in preclinical PDAC models. Unfortunately, the desmoplastic stroma within the PDAC tumor microenvironment establishes a barrier, hindering the infiltration of oncolytic viruses and various therapeutic drugs-such as antibodies, adoptive cell therapy agents, and chemotherapeutic agents-in reaching the tumor site. Recently, a growing emphasis has been placed on targeting major acellular components of tumor stroma, such as hyaluronic acid and collagen, to enhance drug penetration. Oncolytic viruses can be engineered to express proteolytic enzymes that cleave hyaluronic acid and collagen into smaller polypeptides, thereby softening the desmoplastic stroma, ultimately leading to increased viral distribution along with increased oncolysis and subsequent tumor size regression. This approach may offer new possibilities to improve the resectability of patients diagnosed with BR and LA PDAC.

Pulse and CW EPR Oximetry Using Oxychip in Gemcitabine-Treated Murine Pancreatic Tumors

PURPOSE

The goal of this work was to compare pO2 measured using both continuous wave (CW) and pulse electron paramagnetic resonance (EPR) spectroscopy. The Oxychip particle spin probe enabled longitudinal monitoring of pO2 in murine pancreatic tumor treated with gemcitabine during the course of therapy.

PROCEDURES

Pancreatic PanO2 tumors were growing in the syngeneic mice, in the leg. Five doses of saline in control animals or gemcitabine were administered every 3 days, and pO2 was measured after each dose at several time points. Oxygen partial pressure was determined from the linewidth of the CW EPR signal (Bruker E540L) or from the T2 measured using the electron spin echo sequence (Jiva-25™).

RESULTS

The oxygen sensitivity was determined from a calibration curve as 6.1 mG/mm Hg in CW EPR and 68.5 ms-1/mm Hg in pulse EPR. A slight increase in pO2 of up to 20 mm Hg was observed after the third dose of gemcitabine compared to the control. The maximum delta pO2 during the therapy correlated with better survival.

CONCLUSIONS

Both techniques offer fast and reliable oximetry in vivo, allowing to follow the effects of pharmaceutic intervention.

Metabolism and structure of PDA as the target for new therapies: possibilities and limitations for nanotechnology

INTRODUCTION

Certainly, pancreatic ductal adenocarcinoma poses one of the greatest challenges in current oncology. The dense extracellular matrix and low vessel density in PDA tumor impede the effective delivery of drugs, primarily due to the short pharmacokinetics of most drugs and potential electrostatic interactions with stroma components.

AREA COVERED

Owing to the distinctive metabolism of PDA and challenges in accessing nutrients, there is a growing interest in cell metabolism inhibitors as a potential means to inhibit cancer development. However, even if suitable combinations of inhibitors are identified, the question about their administration remains, as the same hindrances that impede effective treatment with conventional drugs will also hinder the delivery of inhibitors. Methods including nanotechnology to increase drugs in PDA penetrations are reviewed and discussed.

EXPERT OPINION

Pancreatic cancer is one of the most difficult tumors to treat due to the small number of blood vessels, high content of extracellular matrix, and specialized resistance mechanisms of tumor cells. One possible method of treating this tumor is the use of metabolic inhibitors in combinations that show synergy. Despite promising results in in vitro tests, their effect is uncertain due to the tumor's structure. In the case of pancreatic cancer, priming of the tumor tissue is required through the sequential administration of drugs that generate blood vessels, increase blood flow, and enhance vascular permeability and extracellular matrix. The use of drug carriers with a size of 10-30 nm may be crucial in the therapy of this cancer.

Targets in the Tumour Matrisome to Promote Cancer Therapy Response

The extracellular matrix (ECM) is composed of complex fibrillar proteins, proteoglycans, and macromolecules, generated by stromal, immune, and cancer cells. The components and organisation of the matrix evolves as tumours progress to invasive disease and metastasis. In many solid tumours, dense fibrotic ECM has been hypothesised to impede therapy response by limiting drug and immune cell access. Interventions to target individual components of the ECM, collectively termed the matrisome, have, however, revealed complex tumour-suppressor, tumour-promoter, and immune-modulatory functions, which have complicated clinical translation. The degree to which distinct components of the matrisome can dictate tumour phenotypes and response to therapy is the subject of intense study. A primary aim is to identify therapeutic opportunities within the matrisome, which might support a better response to existing therapies. Many matrix signatures have been developed which can predict prognosis, immune cell content, and immunotherapy responses. In this review, we will examine key components of the matrisome which have been associated with advanced tumours and therapy resistance. We have primarily focussed here on targeting matrisome components, rather than specific cell types, although several examples are described where cells of origin can dramatically affect tumour roles for matrix components. As we unravel the complex biochemical, biophysical, and intracellular transduction mechanisms associated with the ECM, numerous therapeutic opportunities will be identified to modify tumour progression and therapy response.

Differential expression analysis identifies a prognostically significant extracellular matrix-enriched gene signature in hyaluronan-positive clear cell renal cell carcinoma

Hyaluronan (HA) accumulation in clear cell renal cell carcinoma (ccRCC) is associated with poor prognosis; however, its biology and role in tumorigenesis are unknown. RNA sequencing of 48 HA-positive and 48 HA-negative formalin-fixed paraffin-embedded (FFPE) samples was performed to identify differentially expressed genes (DEG). The DEGs were subjected to pathway and gene enrichment analyses. The Cancer Genome Atlas Kidney Renal Clear Cell Carcinoma (TCGA-KIRC) data and DEGs were used for the cluster analysis. In total, 129 DEGs were identified. HA-positive tumors exhibited enhanced expression of genes related to extracellular matrix (ECM) organization and ECM receptor interaction pathways. Gene set enrichment analysis showed that epithelial-mesenchymal transition-associated genes were highly enriched in the HA-positive phenotype. A protein-protein interaction network was constructed, and 17 hub genes were discovered. Heatmap analysis of TCGA-KIRC data identified two prognostic clusters corresponding to HA-positive and HA-negative phenotypes. These clusters were used to verify the expression levels and conduct survival analysis of the hub genes, 11 of which were linked to poor prognosis. These findings enhance our understanding of hyaluronan in ccRCC.

Breaking-Down Tumoral Physical Barrier by Remotely Unwrapping Metal-Polyphenol-Packaged Hyaluronidase for Optimizing Photothermal/Photodynamic Therapy-Induced Immune Response

The therapy of solid tumors is often hindered by the compact and rigid tumoral extracellular matrix (TECM). Precise reduction of TECM by hyaluronidase (HAase) in combination with nanotechnology is promising for solid tumor therapeutics, yet remains an enormous challenge. Inspired by the treatment of iron poisoning, here a remotely unwrapping strategy is proposed of metal-polyphenol-packaged HAase (named PPFH) by sequentially injecting PPFH and a clinically used iron-chelator deferoxamine (DFO). The in situ dynamic disassembly of PPFH can be triggered by the intravenously injected DFO, resulting in the release, reactivation, and deep penetration of encapsulated HAase inside tumors. Such a cost-effective HAase delivery strategy memorably improves the subsequent photothermal and photodynamic therapy (PTT/PDT)-induced intratumoral infiltration of cytotoxic T lymphocyte cells and the cross-talk between tumor and tumor-draining lymph nodes (TDLN), thereby decreasing the immunosuppression and optimizing tumoricidal immune response that can efficiently protect mice from tumor growth, metastasis, and recurrence in multiple mouse cancer models. Overall, this work presents a proof-of-concept of the dynamic disassembly of metal-polyphenol nanoparticles for extracellular drug delivery as well as the modulation of TECM and immunosuppressive tumor microenvironment.

Evaluation of a deuterated triarylmethyl spin probe for in vivo R2 ∗-based EPR oximetric imaging with enhanced dynamic range

PURPOSE

In this study, we compared two triarylmethyl (TAM) spin probes, Ox071 and Ox063 for their efficacy in measuring tissue oxygen levels under hypoxic and normoxic conditions by R2 *-based EPR oximetry.

METHODS

The R2 * dependencies on the spin probe concentration and oxygen level were calibrated using deoxygenated 1, 2, 5, and 10 mM standard solutions and 2 mM solutions saturated at 0%, 2%, 5%, 10%, and 21% of oxygen. For the hypoxic model, in vivo imaging of a MIA PaCa-2 tumor implanted in the hind leg of a mouse was performed on successive days by R2 *-based EPR oximetry using either Ox071 or Ox063. For the normoxic model, renal imaging of healthy athymic mice was performed using both spin probes. The 3D images were reconstructed by single point imaging and multi-gradient technique was used to determine R2 * maps.

RESULTS

The signal intensities of Ox071 were approximately three times greater than that of Ox063 in the entire partial pressure of oxygen (pO2 ) range investigated. The histograms of the tumor pO2 images were skewed for both spin probes, and Ox071 showed more frequency counts at pO2  > 32 mm Hg. In the normoxic kidney model, there was a clear delineation between the high pO2 cortex and the low pO2 medulla regions. The histogram of high-resolution kidney oximetry image using Ox071 was nearly symmetrical and frequency counts were seen up to 55 mm Hg, which were missed in Ox063 imaging.

CONCLUSION

As an oximetric probe, Ox071 has clear advantages over Ox063 in terms of sensitivity and the pO2 dynamic range.

Dive into the details of radionuclide antibody conjugates: what role do EPR effects and LETs of different radionuclides play?

Radionuclide antibody conjugate (RAC) is a promising diagnostic and therapeutic tool. It combines radionuclides and antibodies by connecting arms and chelating agents, offering precise targeting and potent killing of tumor cells. However, further development and optimization of this radiopharmaceutical is needed to enhance the ultimate substantive efficacy for clinical translation. In this issue of AJNMMI, Strand et al. evaluated the enhanced permeability effect and different linear energy transfer (LET) of radionuclides in a prostate cancer xenograft model. The results showed that specific targeting might negatively influence normal organ uptake when targeting secreted antigens and different LETs of radionuclides might have diverse effects on receptor expression and cell proliferation in tumors. The findings provide new thinking for the development of antibody-based radiopharmaceuticals.

Modulation of the antitumor immune response by cancer-associated fibroblasts: mechanisms and targeting strategies to hamper their immunosuppressive functions

Cancer-associated fibroblasts (CAFs) are highly heterogeneous players that shape the tumor microenvironment and influence tumor progression, metastasis formation, and response to conventional therapies. During the past years, some CAFs subsets have also been involved in the modulation of immune cell functions, affecting the efficacy of both innate and adaptive anti-tumor immune responses. Consequently, the implication of these stromal cells in the response to immunotherapeutic strategies raised major concerns. In this review, current knowledge of CAFs origins and heterogeneity in the tumor stroma, as well as their effects on several immune cell populations that explain their immunosuppressive capabilities are summarized. The current development of therapeutic strategies for targeting this population and their implication in the field of cancer immunotherapy is also highlighted.