Citations

Abstract Purpose: Colorectal cancers with deficient DNA mismatch repair (dMMR) are presumed to uniformly have dense lymphocytic infiltration that underlies their favorable prognosis and is critical to their responsiveness to immunotherapy, as compared with MMR-proficient (pMMR) tumors. We examined T-cell densities and their potential heterogeneity in a large cohort of dMMR tumors. Experimental Design: CD3+ and CD8+ T-cell densities were quantified at the invasive margin (IM) and tumor core (CT) in 561 stage III colon cancers (dMMR, n = 278; pMMR, n = 283) from a phase III adjuvant trial (N0147). Their association with overall survival (OS) was determined using multivariable Cox analysis. Results: Although CD3+ and CD8+ T-cell densities in the tumor microenvironment were higher in dMMR versus pMMR tumors overall, intertumoral heterogeneity in densities between tumors was significantly higher by 30% to 88% among dMMR versus pMMR cancers (P < 0.0001 for all four T-cell subtypes [CD3+IM, CD3+CT, CD8+IM, CD8+CT]). A substantial proportion of dMMR tumors (26% to 35% depending on the T-cell subtype) exhibited T-cell densities as low as that in the bottom half of pMMR tumors. All four T-cell subtypes were prognostic in dMMR with CD3+IM being the most strongly prognostic. Low (vs. high) CD3+IM was independently associated with poorer OS among dMMR (HR, 4.76; 95% confidence interval, 1.43–15.87; P = 0.0019) and pMMR tumors (P = 0.0103). Conclusions: Tumor-infiltrating T-cell densities exhibited greater intertumoral heterogeneity among dMMR than pMMR colon cancers, with CD3+IM providing robust stratification of both dMMR and pMMR tumors for prognosis. Potentially, lower T-cell densities among dMMR tumors may contribute to immunotherapy resistance.

Abstract Motion and uncertainty in radiotherapy is traditionally handled via margins. The clinical target volume (CTV) is expanded to a larger planning target volume (PTV), which is irradiated to the prescribed dose. However, the PTV concept has several limitations, especially in proton therapy. Therefore, robust and probabilistic optimization methods have been developed that directly incorporate motion and uncertainty into treatment plan optimization for intensity modulated radiotherapy (IMRT) and intensity modulated proton therapy (IMPT). Thereby, the explicit definition of a PTV becomes obsolete and treatment plan optimization is directly based on the CTV. Initial work focused on random and systematic setup errors in IMRT. Later, inter-fraction prostate motion and intra-fraction lung motion became a research focus. Over the past ten years, IMPT has emerged as a new application for robust planning methods. In proton therapy, range or setup errors may lead to dose degradation and misalignment of dose contributions from different beams – a problem that cannot generally be addressed by margins. Therefore, IMPT has led to the first implementations of robust planning methods in commercial planning systems, making these methods available for clinical use. This paper first summarizes the limitations of the PTV concept. Subsequently, robust optimization methods are introduced and their applications in IMRT and IMPT planning are reviewed.

Abstract The mechanistic target of rapamycin (mTOR) is a central regulator of cellular proliferation and metabolism. Depending on its binding partners, mTOR is at the core of 2 complexes that either promote protein biosynthesis (mTOR complex 1; mTORC1) or provide survival and proliferation signals (mTORC2). Protein biosynthesis downstream of mTORC1 plays an important role in MYC-driven oncogenesis with translation inhibitors garnering increasing therapeutic attention. The germinal center B-cell oncogene UCHL1 encodes a deubiquitinating enzyme that regulates the balance between mTOR complexes by disrupting mTORC1 and promoting mTORC2 assembly. While supporting mTORC2-dependent growth and survival signals may contribute to its role in cancer, the suppression of mTORC1 activity is enigmatic, as its phosphorylation of its substrate 4EBP1 promotes protein biosynthesis. To address this, we used proximity-based proteomics to identify molecular complexes with which UCH-L1 associates in malignant B cells. We identified a novel association of UCH-L1 with the translation initiation complex eIF4F, the target of 4EBP1. UCH-L1 associates with and promotes the assembly of eIF4F and stimulates protein synthesis through a mechanism that requires its catalytic activity. Because of the importance of mTOR in MYC-driven oncogenesis, we used novel mutant Uchl1 transgenic mice and found that catalytic activity is required for its acceleration of lymphoma in the Eμ-myc model. Further, we demonstrate that mice lacking UCH-L1 are resistant to MYC-induced lymphomas. We conclude that UCH-L1 bypasses the need for mTORC1-dependent protein synthesis by directly promoting translation initiation, and that this mechanism may be essential for MYC in B-cell malignancy.

AbstractBACKGROUNDDroplet digital PCR (ddPCR) is an emerging technology for quantitative cell-free DNA oncology applications. However, assay performance criteria must be established in a standardized manner to harness this potential. We reasoned that standard protocols used in clinical chemistry assay validation should be able to fill this need.METHODSWe validated KRAS, EGFR, and BRAF quantitative ddPCR assays based on the Clinical Laboratory Improvement Act regulations for laboratory-developed tests in clinical chemistry and the matching Clinical and Laboratory Standards Institute guidelines. This included evaluation of limit of the blank (LOB), limit of detection (LOD), limit of quantification (LOQ), intraassay and interassay imprecision, analytical range, dilution linearity, accuracy (including comparison with orthogonal platforms), reference range study, interference, and stability studies.RESULTSFor the ddPCR assays, the LOB was 4 mutant copies, LODs were 12 to 22 copies, and LOQs were 35 to 64 copies. The upper limit of the dynamic range was 30000 copies, and dilutions were linear down to the LOQs with good accuracy of spike recovery of Horizon reference material. Method comparisons with next-generation sequencing and an alternative ddPCR platform showed complete qualitative agreement and quantitative concordance, with slopes of 0.73 to 0.97 and R2s of 0.83 to 0.99. No substantial interferences were discovered. Wild-type copy numbers in plasma ranged from 462 to 6169/mL in healthy individuals.CONCLUSIONSStandard clinical chemistry assay validation protocols can be applied to quantitative ddPCR assays. This should facilitate comparison of the performance of different assays and allow establishment of minimal significant change thresholds in monitoring applications.

Electrically conductive hydrogels incorporated with CNTs support PC12 cell growth and differentiation and hold promise for nerve regeneration.