Biology subjects

Whiting, K.

Publications and source records attributed to Whiting, K..

4 recordsLinked to original sources

bioRxiv2025

Revisiting Tumor Mutational Burden Cutoff: Multi-Study Replicability in Immunotherapy

PURPOSETumor Mutational Burden (TMB) is a crucial biomarker for predicting the effectiveness of cancer immunotherapy. However, ongoing debates about the optimal cutoff significantly impact the clinical application of immunotherapy. The purpose of our study is to comprehensively evaluate TMB cutoffs for predicting immunotherapy outcomes across multiple studies, considering both cancer type and outcome endpoint, using statistically principled approaches. METHODSWe analyzed data from PredictIO, curated through a PubMed search for studies involving immune checkpoint blockade treatment in the adjuvant setting, excluding those involving combinations with chemotherapy, targeted treatment, or radiation. The included studies, published between January 2015 and June 2022, required tumor sequencing data from whole exomes or targeted gene panels for TMB assessment. Outcome endpoints included clinical benefit rate (CBR), progression-free survival (PFS), and overall survival (OS). CBR was defined as the rate of complete response, partial response, or stable disease lasting at least six months, according to RECIST 1.1 criteria. OS and PFS were defined as the interval from treatment initiation to death and disease progression, respectively. TMB was uniformly derived from tumor sequencing data, representing the count of nonsynonymous mutations relative to the target sequencing size. TMB cutoffs were evaluated for outcome associations using study replicability analysis, alongside individual-study analysis and random-effects meta-analysis for comparison. RESULTSThe data provided sufficient evidence of replicable outcome associations for specific TMB cutoffs in melanoma, lung cancer, and bladder cancer. The FDA-recommended cutoff of 10 mutations per megabase showed replicable associations in melanoma for OS (p-value < 0.01) and CBR (p-value < 0.01), though more replicable cutoffs were identified for the latter. Lower cutoffs of 4 and 2 were found to be replicable in lung cancer for CBR (p-value = 0.04) and in bladder cancer for OS (p-value < 0.01), respectively. No cutoff was deemed replicable for the other cancer type and outcome combinations, due to no association, inadequate power, or insufficient data. CONCLUSIONA pan-cancer cutoff of 10 mutations per megabase may not be optimal for predicting immunotherapy outcomes. Further studies are needed to determine appropriate cutoffs specific to cancer types and outcomes through statistically principled replicability analyses.

cancer biology↗

bioRxiv2024

Identification of Pappa and Sall3 as Gli3 direct target genes acting downstream of cilia signalling in corticogenesis

The cerebral cortex is critical for advanced cognitive functions and relies on a vast network of neurons to carry out its highly intricate neural tasks. Generating cortical neurons in accurate numbers hinges on cell signalling orchestrated by primary cilia to coordinate the proliferation and differentiation of cortical stem cells. While recent research has shed light on multiple ciliary roles in corticogenesis, specific mechanisms downstream of cilia signalling remain largely unexplored. We previously showed that an excess of early-born cortical neurons in mice mutant for the ciliary gene Inpp5e was rescued by re-introducing Gli3 repressor. By comparing expression profiles between Inpp5e and Gli3 mutants, we here identified novel Gli3 target genes. This approach highlighted the transcription factor gene Sall3 and Pappalysin1 (Pappa), a metalloproteinase involved in IGF signalling, as up-regulated genes. Further examination revealed that Gli3 directly binds to Sall3 and Pappa enhancers and suppresses their activity in the dorsal telencephalon. Collectively, our analyses provide important mechanistic insights into how primary cilia govern the behaviour of neural stem cells, ultimately ensuring the production of adequate numbers of neurons during corticogenesis. SUMMARY STATEMENTThis study reports how cilia control gene expression via Gli3 in the developing murine cerebral cortex.

developmental biology↗

bioRxiv2021

The ciliary gene INPP5E confers dorsal telencephalic identity to human cortical organoids by negatively regulating Sonic Hedgehog signalling

Defects in primary cilia, cellular antennas that controls multiple intracellular signalling pathways, underlie several neurodevelopmental disorders, but how cilia control essential steps in human brain formation remains elusive. Here, we show that cilia are present on the apical surface of radial glial cells in human foetal forebrain. Interfering with cilia signalling in human organoids by mutating the INPP5E gene leads to the formation of ventral telencephalic cell types instead of cortical progenitors and neurons. INPP5E mutant organoids also showed increased SHH signalling and cyclopamine treatment partially rescued this ventralisation. In addition, ciliary expression of SMO was increased and the integrity of the transition zone was compromised. Overall, these findings establish the importance of primary cilia for dorsal/ventral patterning in human corticogenesis, indicate a tissue specific role of INPP5E as a negative regulator of SHH signalling and have implications for the emerging roles of cilia in the pathogenesis of neurodevelopmental disorders.

developmental biology↗

bioRxiv2019

Root morphology and exudate availability is shaped by particle size and chemistry in Brachypodium distachyon

Root morphology and exudation define a plants sphere of influence in soils, and are in turn shaped by the physiochemical characteristics of soil. We explored how particle size and chemistry of growth substrates affect root morphology and exudation of the model grass Brachypodium distachyon. Root fresh weight and root lengths were correlated with particle size, whereas root number and shoot weight remained constant. Mass spectrometry imaging suggested that both, root length and number shape root exudation. Exudate metabolite profiles detected with liquid chromatography / mass spectrometry were comparable for plants growing in glass beads or sand with various particles sizes, but distinct for plants growing in clay. However, when exudates of clay-grown plants were collected by removing the plants from the substrate, their exudate profile was similar to sand- or glass beads-grown plants. Clay particles sorbed 20% of compounds exuded by clay-grown plants, and 70% of compounds of a defined exudate medium. The sorbed compounds belonged to a range of chemical classes, among them nucleosides/nucleotides, organic acids, sugars, and amino acids. Some of the sorbed compounds could be de-sorbed by a rhizobacterium (Pseudomonas fluorescens WCS415), supporting its growth. We show that root morphology is affected by substrate size, and that root exudation in contrast is not affected by substrate size or chemistry. The availability of exuded compounds, however, depends on the substrate present. These findings further support the critical importance of the physiochemical properties of soils are crucial to consider when investigating plant morphology, exudation, and plant-microbe interactions.

plant biology↗