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Summary: A clearer understanding of the tumor immune microenvironment (TIME) in metastatic clear cell renal cell carcinoma (ccRCC) may help to inform precision treatment strategies. We sought to identify clinically meaningful TIME signatures in ccRCC. We studied tumors from 39 patients with metastatic ccRCC using quantitative multiplexed immunofluorescence and relevant immune marker panels. Cell densities were analyzed in three regions of interest (ROIs): tumor core, tumor–stroma interface and stroma. Patients were stratified into low‐ and high‐marker density groups using median values as thresholds. Log‐rank and Cox regression analyses while controlling for clinical variables were used to compare survival outcomes to patterns of immune cell distributions. There were significant associations with increased macrophage (CD68+CD163+CD206+) density and poor outcomes across multiple ROIs in primary and metastatic tumors. In primary tumors, T‐bet+ T helper type 1 (Th1) cell density was highest at the tumor–stromal interface (P = 0·0021), and increased co‐expression of CD3 and T‐bet was associated with improved overall survival (P = 0·015) and survival after immunotherapy (P = 0·014). In metastatic tumor samples, decreased forkhead box protein 3 (FoxP3)+ T regulatory cell density correlated with improved survival after immunotherapy (P = 0·016). Increased macrophage markers and decreased Th1 T cell markers within the TIME correlated with poor overall survival and treatment outcomes. Immune markers such as FoxP3 showed consistent levels across the TIME, whereas others, such as T‐bet, demonstrated significant variance across the distinct ROIs. These findings suggest that TIME profiling outside the tumor core may identify clinically relevant associations for patients with metastatic ccRCC. [ABSTRACT FROM AUTHOR]

OBJECTIVE Firstly, to evaluate radiotoxicity in a cohort with patients receiving both radiotherapy and a BRAF inhibitor (BRAFi). Secondly, to identify whether the BRAFi used, dabrafenib or vemurafenib, is related to radiotoxicity. DESIGN This study is a retrospective cohort study, reflecting daily clinical practice. METHODS In total, 119 patients were included in this analysis. Patients were treated with vemurafenib (n = 42) or dabrafenib (n = 77) in combination with radiotherapy within a time frame of two months. The incidence of induced radiotoxicity was compared between both groups with a Fisher's exact test. A logistic regression analysis was performed to identify potential factors related to the probability of experiencing induced radiotoxicity: type of BRAFi, combination therapy with a MEK inhibitor, age, sequence of treatment and location, cumulative radiation dose and total incidences of radiotherapy. RESULTS Induced radiotoxicity was seen in 6.7% of all patients. In the vemurafenib group 4.8% of patients experienced induced radiotoxicity compared to 7.8% in the dabrafenib group, this difference was not significant (P = 0.71). The logistic regression analysis revealed that none of the analyzed factors were related to the probability of experiencing induced radiotoxicity. CONCLUSION Both vemurafenib and dabrafenib administered in combination with radiotherapy induced radiotoxicity. No preference for dabrafenib over vemurafenib exists. The induced toxicity was manageable and did not lead to fatalities in this cohort. No predictive factors could be identified. [ABSTRACT FROM AUTHOR]

Background:In cycling tumour cells, the binary cyclin-dependent kinase Cdk4/cyclin D or Cdk2/cyclin E complex is inhibited by p21 following DNA damage to induce G1 cell-cycle arrest. However, it is not known whether other proteins are also recruited within Cdk complexes, or their role, and this was investigated.Methods:Ovarian A2780 tumour cells were exposed to the platinum-based antitumour agent 1R,2R-diaminocyclohexane(trans-diacetato)(dichloro)platinum(IV) (DAP), which preferentially induces G1 arrest in a p21-dependent manner. The Cdk complexes were analysed by gel filtration chromatography, immunoblot and mass spectrometry.Results:The active forms of Cdk4 and Cdk2 complexes in control tumour cells have a molecular size of ∼140 kDa, which increased to ∼290 kDa when inhibited following G1 checkpoint activation by DAP. Proteomic analysis identified Cdk, cyclin, p21 and proliferating cell nuclear antigen (PCNA) in the inhibited complex, and biochemical studies provided unequivocal evidence that the increase in ∼150 kDa of the inhibited complex is consistent with p21-dependent recruitment of PCNA as a trimer, likely bound to three molecules of p21. Although p21 alone was sufficient to inhibit the Cdk complex, PCNA was critical for stabilising p21.Conclusion:G1 Cdk complexes inhibited by p21 also recruit PCNA, which inhibits degradation and, thereby, prolongs activity of p21 within the complex. [ABSTRACT FROM AUTHOR]

The cisplatin analogue 1R,2R-diaminocyclohexane(trans-diacetato)(dichloro)platinum(IV) (DAP) is a DNA-damaging agent that will be entering clinical trials for its potent cytotoxic effects against cisplatin-resistant tumour cells. This cytotoxicity may reside in its ability to selectively activate G1-phase checkpoint response by inhibiting CDKs via the p53/p21 pathway. We have now evaluated the role of another CDK inhibitor p27 as a contributor to DAP-mediated inhibition of G1-phase CDK2 activity. Our studies in ovarian A2780 tumour cells demonstrate that p27 levels induced by DAP are comparable to or greater than those seen for p21. The induction of p27 is not through a transcriptional mechanism, but rather is due to a four-fold increase in protein stabilisation through a mechanism dependent on p21. Moreover, DAP-induced p21 promoted the selective increase of p27 in the CDK2 complex, but not in CDK4 complex, and this selective increase contributed to inhibition of the CDK2 kinase activity. The inhibited complex contained either p27 or p21, but not both, with the relative levels of cyclin E associated with p27 and p21 indicating that about 25% of the inhibition of CDK2 activity was due to p27 and 75% due to p21. This study provides the first evidence that p27 upregulation is directly attributable to activation of the p53/p21 pathway by a DNA-damaging agent, and promulgates p53/p21/p27 axis as a significant component of checkpoint response. [ABSTRACT FROM AUTHOR]

The occurrence of arrhythmias was studied in the 'calcium-paradox' model in the isolated rat heart. Clear relationships were found between the duration of calcium-free perfusion and (a) the occurrence of calcium-free-induced electrophysiological changes, (b) the incidence and duration of subsequently induced calcium-repletion arrhythmias and (c) mechanical recovery at the end of the repletion period. The first signs of electrophysiological changes (i.e. decreased heart rate, T-wave amplitude and increased PQ-interval) and irreversible loss of myocardial recovery occurred during or after 60-90 s of calcium-free perfusion. The occurrence of calcium-repletion induced ventricular tachycardia parallelled this onset of irreversible cardiac injury. These results suggest that the process of calcium washout and subsequent sudden calcium overloading may play a role as a trigger in the pathogenesis of ventricular arrhythmias. [ABSTRACT FROM AUTHOR]