Outcomes of rectal cancer patients who refuse surgery after incomplete clinical response to neoadjuvant therapy.

BACKGROUND AND OBJECTIVES: Total mesorectal excision (TME) remains the standard of care for patients with rectal cancer who have an incomplete response to total neoadjuvant therapy (TNT). A minority of patients will refuse curative intent resection. The aim of this study is to examine the outcomes for these patients. METHODS: A retrospective cohort study of stage 1-3 rectal adenocarcinoma patients who underwent neoadjuvant chemoradiation therapy or TNT at a single institution. Patients either underwent TME, watch-and-wait protocol, or if they refused TME, were counseled and watched (RCW). Clinical outcomes and resource utilization were examined in each group. RESULTS: One hundred seventy-one patients (Male 59%) were included with a median surveillance of 43 months. Twenty-nine patients (17%) refused TME and had shortened overall survival (OS). Twelve patients who refused TME converted to a complete clinical response (cCR) on subsequent staging with a prolonged OS. 92% of these patients had a near cCR at initial staging endoscopy. Increased physician visits and testing was utilized in RCW and WW groups. CONCLUSION: A significant portion of patients convert to cCR and have prolonged OS. Lengthening the time to declare cCR may be considered in select patients, such as those with a near cCR at initial endoscopic staging.

BTK inhibition potentiates anti-PD-L1 treatment in murine melanoma: potential role for MDSC modulation in immunotherapy.

Myeloid-derived suppressor cells (MDSC) have been linked to loss of immune effector cell function through a variety of mechanisms such as the generation of reactive oxygen and nitrogen species and the production of inhibitory cytokines. Our group has shown that signaling through Bruton's tyrosine kinase (BTK) is important for MDSC function. Ibrutinib is an orally administered targeted agent that inhibits BTK activation and is currently used for the treatment of B cell malignancies. Using a syngeneic murine model of melanoma, the effect of BTK inhibition with ibrutinib on the therapeutic response to systemic PD-L1 blockade was studied. BTK was expressed by murine MDSC and their activation was inhibited by ibrutinib. Ibrutinib was not directly cytotoxic to cancer cells in vitro, but it inhibited BTK activation in MDSC and reduced expression of inducible nitric oxide synthase (NOS2) and production of nitric oxide. Ibrutinib treatments decreased the levels of circulating MDSC in vivo and increased the therapeutic efficacy of anti-PD-L1 antibody treatment. Gene expression profiling showed that ibrutinib decreased Cybb (NOX2) signaling, and increased IL-17 signaling (upregulating downstream targets Mmp9, Ptgs2, and S100a8). These results suggest that further exploration of MDSC inhibition could enhance the immunotherapy of advanced melanoma.PrécisInhibition of Bruton's tyrosine kinase, a key enzyme in myeloid cellular function, improves therapeutic response to an anti-PD-L1 antibody in an otherwise fairly resistant murine melanoma model.

Fluorescent Detection of Peroxynitrite Produced by Myeloid-Derived Suppressor Cells in Cancer and Inhibition by Dasatinib.

Myeloid-derived suppressor cells (MDSCs) are immature myeloid cells that expand dramatically in many cancer patients. This expansion contributes to immunosuppression in cancer and reduces the efficacy of immune-based cancer therapies. One mechanism of immunosuppression mediated by MDSCs involves production of the reactive nitrogen species peroxynitrite (PNT), where this strong oxidant inactivates immune effector cells through destructive nitration of tyrosine residues in immune signal transduction pathways. As an alternative to analysis of nitrotyrosines indirectly generated by PNT, we used an endoplasmic reticulum (ER)-targeted fluorescent sensor termed PS3 that allows direct detection of PNT produced by MDSCs. When the MDSC-like cell line MSC2 and primary MDSCs from mice and humans were treated with PS3 and antibody-opsonized TentaGel microspheres, phagocytosis of these beads led to production of PNT and generation of a highly fluorescent product. Using this method, we show that splenocytes from a EMT6 mouse model of cancer, but not normal control mice, produce high levels of PNT due to elevated numbers of granulocytic (PMN) MDSCs. Similarly, peripheral blood mononuclear cells (PBMCs) isolated from blood of human melanoma patients produced substantially higher levels of PNT than healthy human volunteers, coincident with higher peripheral MDSC levels. The kinase inhibitor dasatinib was found to potently block the production of PNT both by inhibiting phagocytosis in vitro and by reducing the number of granulocytic MDSCs in mice in vivo, providing a chemical tool to modulate the production of this reactive nitrogen species (RNS) in the tumor microenvironment.

Effect of Immune Checkpoint Blockade on Myeloid-Derived Suppressor Cell Populations in Patients With Melanoma.

Introduction: Myeloid-derived suppressor cells (MDSC) are a subset of immature myeloid cells that inhibit anti-tumor immunity and contribute to immune therapy resistance. MDSC populations were measured in melanoma patients receiving immune checkpoint inhibitors (ICI). Methods: Patients with melanoma (n=128) provided blood samples at baseline (BL), and before cycles 2 and 3 (BC2, BC3). Peripheral blood mononuclear cells (PBMC) were analyzed for MDSC (CD33+/CD11b+/HLA- DRlo/-) and MDSC subsets, monocytic (CD14+, M-MDSC), granulocytic (CD15+, PMN-MDSC), and early (CD14-/CD15-, E-MDSC) via flow cytometry. Statistical analysis employed unpaired and paired t-tests across and within patient cohorts. Results: Levels of MDSC as a percentage of PBMC increased during ICI (BL: 9.2 ± 1.0% to BC3: 23.6 ± 1.9%, p<0.0001), and patients who developed progressive disease (PD) had higher baseline MDSC. In patients who had a complete or partial response (CR, PR), total MDSC levels rose dramatically and plateaued (BL: 6.4 ± 1.4%, BC2: 26.2 ± 4.2%, BC3: 27.5 ± 4.4%; p<0.0001), whereas MDSC rose less sharply in PD patients (BL: 11.7 ± 2.1%, BC2: 18.3 ± 3.1%, BC3: 19.0 ± 3.2%; p=0.1952). Subset analysis showed that within the expanding MDSC population, PMN-MDSC and E-MDSC levels decreased, while the proportion of M-MDSC remained constant during ICI. In PD patients, the proportion of PMN-MDSC (as a percentage of total MDSC) decreased (BL: 25.1 ± 4.7%, BC2: 16.1 ± 5.2%, BC3: 8.6 ± 1.8%; p=0.0105), whereas a heretofore under-characterized CD14+/CD15+ double positive MDSC subpopulation increased significantly (BL: 8.7 ± 1.4% to BC3: 26.9 ± 4.9%; p=0.0425). Conclusions: MDSC levels initially increased significantly in responders. PMN-MDSC decreased and CD14+CD15+ MDSC increased significantly in PD patients. Changes in MDSC levels may have prognostic value in ICI.

Antibody Conjugation of Fluorescent Nanodiamonds for Targeted Innate Immune Cell Activation.

BACKGROUND: fluorescent nanodiamonds (FND) are nontoxic, infinitely photostable nanoparticles that emit near-infrared fluorescence and have a modifiable surface allowing for the generation of protein-FND conjugates. FND-mediated immune cell targeting may serve as a strategy to visualize immune cells and promote immune cell activation. METHODS: uncoated-FND (uFND) were fabricated, coated with glycidol (gFND), and conjugated with immunoglobulin G (IgG-gFND). In vitro studies were performed using a breast cancer/natural killer/monocyte co-culture system, and in vivo studies were performed using a breast cancer mouse model. RESULTS: in vitro studies demonstrated the targeted immune cell uptake of IgG-gFND, resulting in significant immune cell activation and no compromise in immune cell viability. IgG-gFND remained at the tumor site following intratumoral injection compared to uFND which migrated to the liver and kidneys. CONCLUSION: antibody-conjugated FND may serve as immune drug delivery vehicles with "track and trace capabilities" to promote directed antitumor activity and minimize systemic toxicities.

Pre-operative Sarcopenia Identifies Patients at Risk for Poor Survival After Resection of Biliary Tract Cancers.

INTRODUCTION: Biliary tract cancers (BTC) are aggressive malignancies that require complex surgical procedures. Patients with BTC can present with skeletal muscle depletion, yet the effects of muscle wasting (sarcopenia) on outcomes have not been well studied. The objective of the current study was to define the impact of sarcopenia on survival among patients undergoing resection of BTC. METHODS: Patients who underwent exploration for BTC who had a pre-operative CT scan available for review were identified. Body composition variables including total and psoas muscle area (cm2), muscle density (Hounsfield units), visceral fat area, subcutaneous fat area, and waist-to-hip ratio were analyzed at the level of L3. Outcomes were assessed according to the presence or absence of sarcopenia defined using sex- and BMI-specific threshold values for Psoas Muscle Index (PMI, cm2/m2). RESULTS: Among 117 patients with BTC, 78 (67%) underwent curative-intent resection and 39 (33%) were explored but did not undergo resection due to metastatic/locally advanced disease. Tumor type included distal cholangiocarcinoma (n = 18, 15.4%), hilar cholangiocarcinoma (n = 27, 23.1%), gallbladder carcinoma (n = 52, 44.4%), and intrahepatic cholangiocarcinoma (n = 20, 17.1%). Median patient age was 65.6 years and 43.6% were male. Mean patient BMI was 26.1 kg/m2 among men and 27.5 kg/m2 among women. Overall, 41 (35.0%) patients had sarcopenia. Sarcopenia was associated with an increased risk of death among patients who underwent resection (HR 3.52, 95%CI 1.60-7.78, p = 0.002), which was comparable to patients with unresectable metastatic disease. Other factors such as low serum albumin (HR 3.17, 95% CI 1.30-7.74, p = 0.011) and low psoas density (HR 2.96, 95% CI 1.21-7.21, p = 0.017) were also associated with increased risk of death. Survival was stratified based on sarcopenia, psoas density, and serum albumin. The presence of each variable was associated with an incremental increased risk of death (0 variables ref.; 1 variable HR 3.8, 95% CI 1.0-14, p = 0.043; 2 variables HR 13.1, 95% CI 3.0-57.7, p = 0.001; 3 variables HR 14.6, 95% CI 2.5-87.1, p = 0.003). Patients who had no adverse prognostic factors had a 3-year OS of 67% versus no survival among patients with all 3 factors. CONCLUSIONS: Sarcopenia was common among patients undergoing resection of BTC, occurring in 1 of every 3 patients. Sarcopenia was associated with poor survival after resection, particularly among patients who experienced a recurrence. Body composition metrics such as sarcopenia and low psoas muscle density in addition to low albumin level were able to stratify patients into different prognostic categories.

Management, outcomes, and prognostic factors of ruptured hepatocellular carcinoma: A systematic review.

Ruptured hepatocellular (rHCC) is a rare but life-threatening presentation that often requires acute intervention. In this systematic review we identified 67 eligible studies reporting on 4941 patients with rHCC. Here we present the treatment approaches for the management of rHCC both in the acute setting with regards to management of hemorrhage, as well long-term with regards to oncological treatment.

Stn1-Ten1 is an Rpa2-Rpa3-like complex at telomeres.

In budding yeast, Cdc13, Stn1, and Ten1 form a heterotrimeric complex (CST) that is essential for telomere protection and maintenance. Previous bioinformatics analysis revealed a putative oligonucleotide/oligosaccharide-binding (OB) fold at the N terminus of Stn1 (Stn1N) that shows limited sequence similarity to the OB fold of Rpa2, a subunit of the eukaryotic ssDNA-binding protein complex replication protein A (RPA). Here we present functional and structural analyses of Stn1 and Ten1 from multiple budding and fission yeast. The crystal structure of the Candida tropicalis Stn1N complexed with Ten1 demonstrates an Rpa2N-Rpa3-like complex. In both structures, the OB folds of the two components pack against each other through interactions between two C-terminal helices. The structure of the C-terminal domain of Saccharomyces cerevisiae Stn1 (Stn1C) was found to comprise two related winged helix-turn-helix (WH) motifs, one of which is most similar to the WH motif at the C terminus of Rpa2, again supporting the notion that Stn1 resembles Rpa2. The crystal structure of the fission yeast Schizosaccharomyces pombe Stn1N-Ten1 complex exhibits a virtually identical architecture as the C. tropicalis Stn1N-Ten1. Functional analyses of the Candida albicans Stn1 and Ten1 proteins revealed critical roles for these proteins in suppressing aberrant telomerase and recombination activities at telomeres. Mutations that disrupt the Stn1-Ten1 interaction induce telomere uncapping and abolish the telomere localization of Ten1. Collectively, our structural and functional studies illustrate that, instead of being confined to budding yeast telomeres, the CST complex may represent an evolutionarily conserved RPA-like telomeric complex at the 3' overhangs that works in parallel with or instead of the well-characterized POT1-TPP1/TEBPalpha-beta complex.

A small molecule that disrupts Mdm2-p53 binding activates p53, induces apoptosis and sensitizes lung cancer cells to chemotherapy.

Mdm2 binds to p53 and promotes its degradation. A class of small molecule Mdm2 inhibitors (MI) was recently discovered that binds to Mdm2 and disrupts Mdm2-p53 binding. The efficacy of MI-43 was tested against two pairs of human lung cancer lines differing in p53 status: adenocarcinoma A549 (p53 wild-type, wt) and H522 (p53-null) and non-small cell lung carcinoma H460 (p53wt) and H1299 (p53-null). MI-43 induced the accumulation of p53 and its downstream target genes, Mdm2, p21, Noxa and Puma only in wt p53-containing cells, indicating that disruption of Mdm2-p53 binding increases p53, which is transcriptionally active. MI-43 preferentially inhibited the growth of wt p53-containing cells in a p53 dependent manner, but was much less effective in p53-null cells. Mechanistically, MI-43 induced G(1) or G(2) arrest at low concentration as result of p21 induction, and apoptosis at high concentration due to Puma/Noxa induction. Importantly, MI-43 is much less toxic to normal fetal lung fibroblast, MRC5 cells. Finally, when used in combination, MI-43 sensitized chemo-resistant A549 cells to etoposide-induced apoptosis. Thus, MI-43 or its analogues could be further developed as a novel class of anticancer drug for lung cancer cells harboring wt p53 as a single agent or in combination with chemo-drugs.