Clinical and Biological Activity of Chemoimmunotherapy in Advanced Endometrial Adenocarcinoma: A Phase II Trial of the Big Ten Cancer Research Consortium.

Purpose: The objective of this study was to assess the efficacy and safety of pembrolizumab in combination with standard carboplatin/paclitaxel in patients with advanced endometrial cancer (EC). Patients and Methods: This single-arm, open-label, multi-center phase II study enrolled patients with RECIST measurable advanced EC. Patients could have received < 1 prior platinum-based regimen and < one non-platinum chemotherapy. The primary endpoint was objective response rate (ORR). Planned sample size of 46 subjects provided 80% power to detect 15% ORR improvement compared to historical control rate of 50%. Results: 46 patients were enrolled, and 43 were evaluable for ORR. Median age was 66 (range: 43-86). Thirty-four (73.9%) patients had recurrent and 12 (26.1%) primary metastatic EC. Patients received carboplatin AUC 6, paclitaxel 175mg/m2 and pembrolizumab 200mg IV every 3 weeks for up to 6 cycles. ORR was 74.4% (32/43), higher than historic controls (p = 0.001). Median PFS was 10.6 months (95% CI 8.3-13.9 months). The most common grade 1-2 treatment related adverse event (TRAEs) included anemia (56.5%), alopecia (47.8%), fatigue (47.8%) and neuropathy (13%), while the most common grade 3-4 TRAEs were lymphopenia, leukopenia, and anemia (19.6% each). High-dimensional spectral flow cytometry (CyTEK) identified enrichment in peripheral CD8+ and CD4+ T cell populations at baseline in responders. The CD8+ T cell compartment in responders exhibited greater expression levels of PD-1 and PD-L1 and higher abundance of effector memory CD8+ cells compared to non-responders. Conclusions: Addition of pembrolizumab to carboplatin and paclitaxel for advanced EC was tolerated and improved ORR compared to historical outcomes.

SPOROS: A pipeline to analyze DISE/6mer seed toxicity.

microRNAs (miRNAs) are (18-22nt long) noncoding short (s)RNAs that suppress gene expression by targeting the 3' untranslated region of target mRNAs. This occurs through the seed sequence located in position 2-7/8 of the miRNA guide strand, once it is loaded into the RNA induced silencing complex (RISC). G-rich 6mer seed sequences can kill cells by targeting C-rich 6mer seed matches located in genes that are critical for cell survival. This results in induction of Death Induced by Survival gene Elimination (DISE), through a mechanism we have called 6mer seed toxicity. miRNAs are often quantified in cells by aligning the reads from small (sm)RNA sequencing to the genome. However, the analysis of any smRNA Seq data set for predicted 6mer seed toxicity requires an alternative workflow, solely based on the exact position 2-7 of any short (s)RNA that can enter the RISC. Therefore, we developed SPOROS, a semi-automated pipeline that produces multiple useful outputs to predict and compare 6mer seed toxicity of cellular sRNAs, regardless of their nature, between different samples. We provide two examples to illustrate the capabilities of SPOROS: Example one involves the analysis of RISC-bound sRNAs in a cancer cell line (either wild-type or two mutant lines unable to produce most miRNAs). Example two is based on a publicly available smRNA Seq data set from postmortem brains (either from normal or Alzheimer's patients). Our methods (found at https://github.com/ebartom/SPOROS and at Code Ocean: https://doi.org/10.24433/CO.1732496.v1) are designed to be used to analyze a variety of smRNA Seq data in various normal and disease settings.

Identification of the toxic 6mer seed consensus for human cancer cells.

6mer seed toxicity is a novel cell death mechanism that kills cancer cells by triggering death induced by survival gene elimination (DISE). It is based on si- or shRNAs with a specific G-rich nucleotide composition in position 2-7 of their guide strand. An arrayed screen of 4096 6mer seeds on two human and two mouse cell lines identified G-rich 6mers as the most toxic seeds. We have now tested two additional cell lines, one human and one mouse, identifying the GGGGGC consensus as the most toxic average 6mer seed for human cancer cells while slightly less significant for mouse cancer cells. RNA Seq and bioinformatics analyses suggested that an siRNA containing the GGGGGC seed (siGGGGGC) is toxic to cancer cells by targeting GCCCCC seed matches located predominantly in the 3' UTR of a set of genes critical for cell survival. We have identified several genes targeted by this seed and demonstrate direct and specific targeting of GCCCCC seed matches, which is attenuated upon mutation of the GCCCCC seed matches in these 3' UTRs. Our data show that siGGGGGC kills cancer cells through its miRNA-like activity and points at artificial miRNAs, si- or shRNAs containing this seed as a potential new cancer therapeutics.

Tetracycline-exposed Drosophila melanogaster males produce fewer offspring but a relative excess of sons.

A large diversity of species possesses endosymbionts; these endosymbionts can exhibit mutualistic, parasitic, and commensal relationships with their hosts. Previous work has consistently revealed that depleting endosymbiont titer with antibiotic treatment can significantly alter host fitness and function, particularly with respect to reproductive phenotypes. Although these findings are often interpreted as resulting from the breakdown of highly coevolved symbioses, it is possible that antibiotic treatment itself rather than endosymbiont removal contributes to the observed perturbations in reproductive phenotypes. Here, we investigate the effect of tetracycline treatment on sex ratio and male reproductive fitness using Drosophila melanogaster as a model system. Our results indicate that tetracycline-treated males produce a relative excess of sons. We also find that tetracycline treatment reduces the number of progeny produced by treated males but not treated females. These findings are independent of the effects of tetracycline on Wolbachia titer and implicate the antibiotic itself as mediating these changes. It is yet unclear whether the sex ratio shift and reduction in male reproductive fitness are direct or indirect consequences of tetracycline exposure, and more work is needed to determine the molecular mechanisms by which these disturbances in reproductive phenotypes arise. Our data highlight the importance of considering the potentially confounding effects of antibiotic treatment when investigating the effects of endosymbiont depletion on host phenotypes.