I obtained my undergraduate degree (BSc) in Molecular Biomedicine from the University of Copenhagen (2010-2013), after which I moved to Cambridge, UK to complete an MPhil in Medical Science, under the supervision of Prof Susan Ozanne and Prof Kenneth Siddle at the Metabolic Research Laboratories - Institute of Metabolic Science (Wellcome Trust-MRC). My MPhil research focused on the contribution of microRNAs to the development of insulin resistance as a result of a suboptimal nutritional environment in utero.

I subsequently completed a four-year Wellcome Trust PhD Programme in Metabolic and Cardiovascular Disease (2014-2018), with an initial MRes year. During my PhD with Prof Robert Semple, I engineered the first human induced pluripotent stem cell models with endogenous expression of either one or two copies of the cancer-associated PIK3CA-H1047R variant. Our initial aim was to study the potential mechanisms whereby this mutation causes rare, developmental overgrowth disorders known as PIK3CA-related overgrowth spectrum (PROS). In the course of this work, we discovered allele dose-dependent effects of genetic PI3Ka activation, suggesting that there are quantitative PI3K signalling thresholds that may determine the pathophysiological consequences of PIK3CA mutations in human diseases, most notably cancer.

After a short postdoc in the Semple Lab upon its move to the University of Edinburgh (2018-2019), I joined the laboratory of Prof Bart Vanhaesebroeck at University College London. From 2019-2020, I worked on developing highly robust, cell-based quantitative assays for studies of small molecule-mediated PIK3CA activation. In a separate project, I also used computational approaches to identify evidence for dose-dependent PI3K signalling activation in human breast cancers with one or multiple copies of activating PIK3CA mutations.

In December 2020, I was awarded a Sir Henry Wellcome Postdoctoral Fellowship to study the systems biology of PI3K-dependent phenotypic plasticity, with primary basis at UCL Cancer Institute and the CellSig laboratory of Prof Bart Vanhaesebroeck. I developed novel cellular systems for quantitative, single-cell PI3K signalling studies and applied them to studies of growth factor-specific PI3K signalling fingerprints in different genetic contexts. During this time, I also benefited from a collaboration with Prof Alex Toker at Beth Israel Deaconess Medical Center, in which we focused on the discovery of novel aspects of AKT biology through a multiomic characterisation of a second-generation AKT degrader.

In May 2023, I transferred my fellowship to the MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, to continue my research as an Independent Investigator.

Outside the lab, I am involved in national and international efforts to promote Open Research. On 1 May 2022, I was appointed to serve on the inaugural UK Committee on Research Integrity (https://ukcori.org/our-people/) for an initial term of 3 years, representing the voice of early career researchers in efforts to champion research integrity and a positive research culture across the UK.

Finally, I am committed to supporting the community of PROS patients. I serve on the scientific advisory board of CLOVES Syndrome Community (https://clovessyndrome.org/who-we-are/#smab) and chair the PIK3CA Related Conditions Research Roundtable.

My research aims to understand how quantitative phosphoinositide 3-kinase (PI3K) signalling underpins context-dependent information transmission in mammalian cells, and to use this knowledge to identify novel therapeutic options for diseases of aberrant PI3K signalling. I am committed to achieving this aim through:

• Research with integrity (https://ukcori.org/what-research-integrity-is/)
• Transparent sharing of all our results without unnecessary delays (https://ralitsamadsen.wordpress.com/open-science/)
• Care and respect for others (https://ralitsamadsen.wordpress.com/teaching/)

At present, my research is driven by an unmet need for better therapies for PIK3CA-related disorders. It is my conviction that this need can only be met through a transition from a largely qualitative to a fully quantitative understanding of PI3K signalling.

The human PIK3CA gene codes for the catalytic subunit of the ubiquitously expressed phosphoinositide 3-kinase alpha (PI3Kα), an enzymatic complex that is crucial for transducing signals from growth factor-specific receptor tyrosine kinases, including IGF1R, INSR, EGFR and many others. Recent work by myself and others has demonstrated that the landscape and biochemical consequences of genetic PI3Ka activation are more complex than previously appreciated. For example, a heterozygous, activating PIK3CA-H1047R mutation results in increased PI3K signalling but no overt phenotypic reprogramming of human induced pluripotent stem cells; in contrast, homozygous expression of the same variant in the same cellular context results in transcriptomic rewiring, constitutive stemness and pluripotency loss. Evidence for dose-dependent effects of PI3K signalling activation, with relevance for disease outcome, can also be found in publicly available breast cancer datasets. Collectively, these findings hint at the existence of poorly defined biochemical thresholds which, along with short-and long-term temporal control of signalling activity, determine the phenotypic output of aberrant PI3K activation in human disease.

While the typically static, pictorial representations of signalling pathways in textbooks and reviews may give the impression of linear information transfer and signalling control, the reality is far more complicated. A quantitative understanding of PI3K signalling therefore requires a multidisciplinary approach, featuring a firm grasp of quantitative biochemistry, cell biology, and computational modelling. These facets must be considered in the context of the wider disease biology that we seek to modify, including attention to unintended consequences on normal human physiology. I therefore work according to a classical systems biology approach that covers the following objectives:

1. The development of quantitative signalling maps (akin to electronic circuits) that depict how the PI3K network transduces a specific environmental signal in different cell types. Using quantitative set-ups (2D/3D single cell signalling, live-cell microscopy of PI3K activity) developed during my Sir Henry Wellcome Fellowship, alongside computational and mathematical biology, our experiments seek to decipher the mechanisms used by cells to encode growth factor identity through spatiotemporal PI3K signalling.

2. The engineering of human induced pluripotent stem cell (iPSC)-derived disease models with controlled expression of activating PIK3CA mutations. Aided by quantitative phenotyping, mathematical modelling and the unique capacity of iPSCs to differentiate into derivatives of all three germ layers (mesoderm, endoderm, ectoderm), these models will be used to: a. understand the molecular mechanisms underpinning the ability of PI3Kα to control cell fate decisions in a dose-dependent manner, including identification of “points-of-no-return” that are no longer reversible by simple PI3Kα inhibition; b. to test candidate therapiesidentified in (1) in lineage-specific and more disease-relevant settings, with a focus on fine-tuning rather than complete ablation of critical signalling components.