Value of 68Ga-labeled bombesin antagonist (RM2) in the detection of primary prostate cancer comparing with [18F]fluoromethylcholine PET-CT and multiparametric MRI-a phase I/II study.

OBJECTIVES: The bombesin derivative RM2 is a GRPr antagonist with strong binding affinity to prostate cancer (PCa). In this study, the impact of [68Ga]Ga-RM2 positron emission tomography-computed tomography (PET-CT) for the detection of primary PCa was compared with that of [18F]FCH PET-CT and multiparametric magnetic resonance imaging (mpMRI). METHODS: This phase I/II study was conducted in 30 biopsy-positive PCa subjects. The patients were stratified into high (10 patients), intermediate (10 patients), and low risk (10 patients) for extraglandular metastases as defined by National Comprehensive Cancer Network (NCCN) criteria (NCCN Clinical Practice Guidelines in Oncology, 2016). The prostate gland was classified in 12 anatomic segments for data analysis of the imaging modalities as well as histopathologic findings. The segment with the highest radiotracer uptake was defined as the "index lesion." All cases were scheduled to undergo prostatectomy with pelvic lymph node (LN) dissection in intermediate- and high-risk patients. Intraprostatic and pelvic nodal [68Ga]Ga-RM2 and [18F]FCH PET-CT findings were correlated with mpMRI and histopathologic results. RESULTS: Of the 312 analyzed regions, 120 regions (4 to 8 lesions per patient) showed abnormal findings in the prostate gland. In a region-based analysis, overall sensitivity and specificity of [68Ga]Ga-RM2 PET-CT in the detection of primary tumor were 74% and 90%, respectively, while it was 60% and 80% for [18F]FCH PET-CT and 72% and 89% for mpMRI. Although the overall sensitivity of [68Ga]Ga-RM2 PET-CT was higher compared to that of [18F]FCH PET-CT and mpMRI, the statistical analysis showed only significant difference between [68Ga]Ga-RM2 PET-CT and [18F]FCH PET-CT in the intermediate-risk group (p = 0.01) and [68Ga]Ga-RM2 PET-CT and mpMRT in the high-risk group (p = 0.03). In the lesion-based analysis, there was no significant difference between SUVmax of [68Ga]Ga-RM2 and [18F]FCH PET-CT in the intraprostatic malignant lesions ([68Ga]Ga-RM2: mean SUVmax: 5.98 ± 4.13, median: 4.75; [18F]FCH: mean SUVmax: 6.08 ± 2.74, median: 5.5; p = 0.13). CONCLUSIONS: [68Ga]Ga-RM2 showed promising PET tracer for the detection of intraprostatic PCa in a cohort of patients with different risk stratifications. However, significant differences were only found between [68Ga]Ga-RM2 PET-CT and [18F]FCH PET-CT in the intermediate-risk group and [68Ga]Ga-RM2 PET-CT and mpMRT in the high-risk group. In addition, GRP-R-based imaging seems to play a complementary role to choline-based imaging for full characterization of PCa extent and biopsy guidance in low- and intermediate-metastatic-risk PCa patients and has the potential to discriminate them from those at higher risks. KEY POINTS: • [68Ga]Ga-RM2 is a promising PET tracer with a high detection rate for intraprostatic PCa especially in intermediate-risk prostate cancer patients. • GRPr-based imaging seems to play a complementary role to choline-based or PSMA-based PET/CT imaging in selected low- and intermediate-risk PCa patients for better characterization and eventually biopsy guidance of prostate cancer disease.

Imaging GRPr Expression in Metastatic Castration-Resistant Prostate Cancer with [68Ga]Ga-RM2-A Head-to-Head Pilot Comparison with [68Ga]Ga-PSMA-11.

BACKGROUND: The gastrin-releasing peptide receptor (GRPr) is highly overexpressed in several solid tumors, including treatment-naïve and recurrent prostate cancer. [68Ga]Ga-RM2 is a well-established radiotracer for PET imaging of GRPr, and [177Lu]Lu-RM2 has been proposed as a therapeutic alternative for patients with heterogeneous and/or low expression of PSMA. In this study, we aimed to evaluate the expression of GRPr and PSMA in a group of patients diagnosed with castration-resistant prostate cancer (mCRPC) by means of PET imaging. METHODS: Seventeen mCRPC patients referred for radio-ligand therapy (RLT) were enrolled and underwent [68Ga]Ga-PSMA-11 and [68Ga]Ga-RM2 PET/CT imaging, 8.8 ± 8.6 days apart, to compare the biodistribution of each tracer. Uptake in healthy organs and tumor lesions was assessed by SUV values, and tumor-to-background ratios were analyzed. RESULTS: [68Ga]Ga-PSMA-11 showed significantly higher uptake in tumor lesions in bone, lymph nodes, prostate, and soft tissues and detected 23% more lesions compared to [68Ga]Ga-RM2. In 4/17 patients (23.5%), the biodistribution of both tracers was comparable. CONCLUSIONS: Our results show that in our cohort of mCRPC patients, PSMA expression was higher compared to GRPr. Nevertheless, RLT with [177Lu]Lu-RM2 may be an alternative treatment option for selected patients or patients in earlier disease stages, such as biochemical recurrence.

A randomised controlled trial of a digital intervention (Renewed) to support symptom management, wellbeing and quality of life in cancer survivors.

BACKGROUND: Many cancer survivors following primary treatment have prolonged poor quality of life. AIM: To determine the effectiveness of a bespoke digital intervention to support cancer survivors. DESIGN: Pragmatic parallel open randomised trial. SETTING: UK general practices. METHODS: People having finished primary treatment (<= 10 years previously) for colo-rectal, breast or prostate cancers, with European-Organization-for-Research-and-Treatment-of-Cancer QLQ-C30 score <85, were randomised by online software to: 1)detailed 'generic' digital NHS support ('LiveWell';n=906), 2) a bespoke complex digital intervention ('Renewed';n=903) addressing symptom management, physical activity, diet, weight loss, distress, or 3) 'Renewed-with-support' (n=903): 'Renewed' with additional brief email and telephone support. RESULTS: Mixed linear regression provided estimates of the differences between each intervention group and generic advice: at 6 months (primary time point: n's respectively 806;749;705) all groups improved, with no significant between-group differences for EORTC QLQ-C30, but global health improved more in both intervention groups. By 12 months there were: small improvements in EORTC QLQ-C30 for Renewed-with-support (versus generic advice: 1.42, 95% CIs 0.33-2.51); both groups improved global health (12 months: renewed: 3.06, 1.39-4.74; renewed-with-support: 2.78, 1.08-4.48), dyspnoea, constipation, and enablement, and lower NHS costs (generic advice £265: in comparison respectively £141 (153-128) and £77 (90-65) lower); and for Renewed-with-support improvement in several other symptom subscales. No harms were identified. CONCLUSION: Cancer survivors quality of life improved with detailed generic online support. Robustly developed bespoke digital support provides limited additional short term benefit, but additional longer term improvement in global health enablement and symptom management, with substantially lower NHS costs.

Identification of MHC-I-Presented Porcine Respiratory and Reproductive Syndrome Virus (PRRSV) Peptides Reveals Immunogenic Epitopes within Several Non-Structural Proteins Recognized by CD8+ T Cells.

Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most relevant porcine pathogens worldwide. Active control of the disease relies on modified live virus vaccines (MLVs), as most inactivated vaccines provide very limited protection. Neutralizing antibodies occur late in infection; therefore, CD8+ T cells are considered important correlates of protection and are a frequent focus of investigation. Our aim was to identify viral peptides naturally bound by the class I major histocompatibility complex (MHC-I) and to confirm their ability to stimulate CD8+ T cells. For this purpose, we immunoprecipitated MHC-I/peptide complexes of PRRSV (strain AUT15-33) -infected cells (SLA-I Lr-Hp 35.0/24 mod) to isolate the viral epitopes and analyzed them with liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Furthermore, we employed these identified peptides to stimulate peripheral blood mononuclear cells (PBMCs) of previously PRRSV-infected pigs and measured the PRRSV-specific CD8+ T-cell response with an intracellular cytokine staining (ICS). Our data revealed that PRRSV non-structural proteins (NSPs), encoded in open reading frame 1a and 1b (ORF1), present the major source of MHC-I-presented peptides. Additionally, we show that our identified epitopes are able to trigger IFNγ responses in vitro. These findings are a basis for understanding the proteasomal degradation of PRRSV proteins, the cellular ability to display them via MHC-I, and their potential to restimulate CD8+ T cells.

10% Body weight (gain) change as criterion for the maximum tolerated dose: A critical analysis.

The concept of the Maximum Tolerated Dose (MTD) was introduced in the seventies for carcinogenicity testing and was defined as the highest dose inducing clear toxicity, but not mortality by causes other than cancer. As estimation of the MTD in a carcinogenicity study, the highest dose that causes a 10% decrease in body weight compared to control animals over the course of a 90-day study, was formulated as a suitable criterion. This criterion was not seen as indicator of excessive toxicity but as a means to avoid false negative outcomes in a carcinogenicity study, as tumor formation may be reduced when body weight is significantly decreased. The body weight-based MTD criterion, however, turned up in carcinogenicity test guidelines and guidance (e.g., from OECD) as the highest dose that causes a 10% decrease in body weight gain relative to controls. Moreover, the 10% decrease in body weight gain criterion for MTD also ended up in test guidelines and guidances for toxicity endpoints other than carcinogenicity, so outside the context it was intended for. A 10% decrease in body weight gain relative to controls is however not a biologically relevant effect as it corresponds to less than 3% body weight reduction relative to controls in a 90-day study, which is within the normal variation in body weight. It therefore should certainly not be considered as a condition of excessive toxicity. Using the 10% lower weight gain criterion and incorrectly associating it with excessive toxicity has major implications for top dose selection in regulatory safety studies, resulting in tests performed at doses too low to elicit toxicity. This negatively impacts the reliability of studies and their regulatory usability; moreover, it results in a waste of experimental animals, which is ethically highly undesirable. Hence, our plea is to remove this MTD criterion for top dose selection in test guidelines and guidances for toxicity endpoints other than carcinogenicity and to reinstall the original 10% decrease in body weight criterion in test guidelines and guidances for carcinogenicity.

E-&mHealth interventions targeting nutrition, physical activity, sedentary behavior, and/or obesity among children: A scoping review of systematic reviews and meta-analyses.

Childhood obesity is a public health concern. Electronic and mobile health (e-&mHealth) approaches can facilitate the delivery of interventions for obesity prevention and treatment. Synthesizing reviews of e-&mHealth interventions to improve weight and weight-related behaviors (physical activity, sedentary behavior, and diet) is useful to characterize the current scope of the literature and identify opportunities for future reviews and studies. Using a scoping review methodology, we aimed to evaluate the breadth and methodological quality of systematic reviews and meta-analyses of e-&mHealth interventions targeting weight and weight-related behaviors in children and adolescents aged <19 years. A systematic search of seven databases was conducted, including reviews published between 2000 and 2019. Review characteristics were extracted, and methodological quality was assessed using the AMSTAR 2 tool. Forty-five systematic reviews and meta-analyses were included. All reviews evaluated intervention efficacy (100%), but few assessed other aspects (20% in total) such as cost-effectiveness. Smartphone applications (47%), text messages (44%), and websites (35%) were the main modalities. Weight (60%), physical activity (51%), and diet (44%) were frequently assessed, unlike sedentary behavior (8%). Most reviews were rated as having critically low or low methodological quality (97%). Reviews that identify the effective active ingredients of interventions and explore metrics beyond efficacy are recommended.

High-throughput drug screening identifies the ATR-CHK1 pathway as a therapeutic vulnerability of CALR mutated hematopoietic cells.

Mutations of calreticulin (CALR) are the second most prevalent driver mutations in essential thrombocythemia and primary myelofibrosis. To identify potential targeted therapies for CALR mutated myeloproliferative neoplasms, we searched for small molecules that selectively inhibit the growth of CALR mutated cells using high-throughput drug screening. We investigated 89 172 compounds using isogenic cell lines carrying CALR mutations and identified synthetic lethality with compounds targeting the ATR-CHK1 pathway. The selective inhibitory effect of these compounds was validated in a co-culture assay of CALR mutated and wild-type cells. Of the tested compounds, CHK1 inhibitors potently depleted CALR mutated cells, allowing wild-type cell dominance in the co-culture over time. Neither CALR deficient cells nor JAK2V617F mutated cells showed hypersensitivity to ATR-CHK1 inhibition, thus suggesting specificity for the oncogenic activation by the mutant CALR. CHK1 inhibitors induced replication stress in CALR mutated cells revealed by elevated pan-nuclear staining for γH2AX and hyperphosphorylation of RPA2. This was accompanied by S-phase cell cycle arrest due to incomplete DNA replication. Transcriptomic and phosphoproteomic analyses revealed a replication stress signature caused by oncogenic CALR, suggesting an intrinsic vulnerability to CHK1 perturbation. This study reveals the ATR-CHK1 pathway as a potential therapeutic target in CALR mutated hematopoietic cells.

eHealth interventions targeting nutrition, physical activity, sedentary behavior, or obesity in adults: A scoping review of systematic reviews.

A vast body of evidence regarding eHealth interventions for nutrition, physical activity, sedentary behavior, and obesity exists. This scoping review of systematic reviews aimed to evaluate the current level of evidence in this growing field. Seven electronic databases were searched for systematic reviews published until October 27, 2019. The systematic reviews must have included adult participants only and have evaluated eHealth behavioral interventions with the primary aim of changing nutrition, physical activity, and sedentary behavior or treating or preventing overweight and obesity. One hundred and six systematic reviews, published from 2006 to 2019, were included. Almost all (n = 98) reviews evaluated the efficacy of interventions. Over half (n = 61) included interventions focused on physical activity, followed by treatment of obesity (n = 28), nutrition (n = 22), prevention of obesity (n = 18), and sedentary behavior (n = 6). Many reviews (n = 46) evaluated one type of eHealth intervention only, while 60 included two or more types. Most reviews (n = 67) were rated as being of critically low methodological quality. This scoping review identified an increasing volume of systematic reviews evaluating eHealth interventions. It highlights several evidence gaps (e.g., evaluation of other outcomes, such as reach, engagement, or cost effectiveness), guiding future research efforts in this area.

mHealth Interventions to Address Physical Activity and Sedentary Behavior in Cancer Survivors: A Systematic Review.

This review aimed to identify, evaluate, and synthesize the scientific literature on mobile health (mHealth) interventions to promote physical activity (PA) or reduce sedentary behavior (SB) in cancer survivors. We searched six databases from 2000 to 13 April 2020 for controlled and non-controlled trials published in any language. We conducted best evidence syntheses on controlled trials to assess the strength of the evidence. All 31 interventions included in this review measured PA outcomes, with 10 of them also evaluating SB outcomes. Most study participants were adults/older adults with various cancer types. The majority (n = 25) of studies implemented multicomponent interventions, with activity trackers being the most commonly used mHealth technology. There is strong evidence for mHealth interventions, including personal contact components, in increasing moderate-to-vigorous intensity PA among cancer survivors. However, there is inconclusive evidence to support mHealth interventions in increasing total activity and step counts. There is inconclusive evidence on SB potentially due to the limited number of studies. mHealth interventions that include personal contact components are likely more effective in increasing PA than mHealth interventions without such components. Future research should address social factors in mHealth interventions for PA and SB in cancer survivors.

Acute BAF perturbation causes immediate changes in chromatin accessibility.

Cancer-associated, loss-of-function mutations in genes encoding subunits of the BRG1/BRM-associated factor (BAF) chromatin-remodeling complexes1-8 often cause drastic chromatin accessibility changes, especially in important regulatory regions9-19. However, it remains unknown how these changes are established over time (for example, immediate consequences or long-term adaptations), and whether they are causative for intracomplex synthetic lethalities, abrogating the formation or activity of BAF complexes9,20-24. In the present study, we use the dTAG system to induce acute degradation of BAF subunits and show that chromatin alterations are established faster than the duration of one cell cycle. Using a pharmacological inhibitor and a chemical degrader of the BAF complex ATPase subunits25,26, we show that maintaining genome accessibility requires constant ATP-dependent remodeling. Completely abolishing BAF complex function by acute degradation of a synthetic lethal subunit in a paralog-deficient background results in an almost complete loss of chromatin accessibility at BAF-controlled sites, especially also at superenhancers, providing a mechanism for intracomplex synthetic lethalities.

Biomolecular condensation of NUP98 fusion proteins drives leukemogenic gene expression.

NUP98 fusion proteins cause leukemia via unknown molecular mechanisms. All NUP98 fusion proteins share an intrinsically disordered region (IDR) in the NUP98 N terminus, featuring repeats of phenylalanine-glycine (FG), and C-terminal fusion partners often function in gene control. We investigated whether mechanisms of oncogenic transformation by NUP98 fusion proteins are hardwired in their protein interactomes. Affinity purification coupled to mass spectrometry (MS) and confocal imaging of five NUP98 fusion proteins expressed in human leukemia cells revealed that shared interactors were enriched for proteins involved in biomolecular condensation and that they colocalized with NUP98 fusion proteins in nuclear puncta. We developed biotinylated isoxazole-mediated condensome MS (biCon-MS) to show that NUP98 fusion proteins alter the global composition of biomolecular condensates. An artificial FG-repeat-containing fusion protein phenocopied the nuclear localization patterns of NUP98 fusion proteins and their capability to drive oncogenic gene expression programs. Thus, we propose that IDR-containing fusion proteins combine biomolecular condensation with transcriptional control to induce cancer.

Rational discovery of molecular glue degraders via scalable chemical profiling.

Targeted protein degradation is a new therapeutic modality based on drugs that destabilize proteins by inducing their proximity to E3 ubiquitin ligases. Of particular interest are molecular glues that can degrade otherwise unligandable proteins by orchestrating direct interactions between target and ligase. However, their discovery has so far been serendipitous, thus hampering broad translational efforts. Here, we describe a scalable strategy toward glue degrader discovery that is based on chemical screening in hyponeddylated cells coupled to a multi-omics target deconvolution campaign. This approach led us to identify compounds that induce ubiquitination and degradation of cyclin K by prompting an interaction of CDK12-cyclin K with a CRL4B ligase complex. Notably, this interaction is independent of a dedicated substrate receptor, thus functionally segregating this mechanism from all described degraders. Collectively, our data outline a versatile and broadly applicable strategy to identify degraders with nonobvious mechanisms and thus empower future drug discovery efforts.

Selective Mediator dependence of cell-type-specifying transcription.

The Mediator complex directs signals from DNA-binding transcription factors to RNA polymerase II (Pol II). Despite this pivotal position, mechanistic understanding of Mediator in human cells remains incomplete. Here we quantified Mediator-controlled Pol II kinetics by coupling rapid subunit degradation with orthogonal experimental readouts. In agreement with a model of condensate-driven transcription initiation, large clusters of hypophosphorylated Pol II rapidly disassembled upon Mediator degradation. This was accompanied by a selective and pronounced disruption of cell-type-specifying transcriptional circuits, whose constituent genes featured exceptionally high rates of Pol II turnover. Notably, the transcriptional output of most other genes was largely unaffected by acute Mediator ablation. Maintenance of transcriptional activity at these genes was linked to an unexpected CDK9-dependent compensatory feedback loop that elevated Pol II pause release rates across the genome. Collectively, our work positions human Mediator as a globally acting coactivator that selectively safeguards the functionality of cell-type-specifying transcriptional networks.

Developing a digital intervention for cancer survivors: an evidence-, theory- and person-based approach.

This paper illustrates a rigorous approach to developing digital interventions using an evidence-, theory- and person-based approach. Intervention planning included a rapid scoping review that identified cancer survivors' needs, including barriers and facilitators to intervention success. Review evidence (N = 49 papers) informed the intervention's Guiding Principles, theory-based behavioural analysis and logic model. The intervention was optimised based on feedback on a prototype intervention through interviews (N = 96) with cancer survivors and focus groups with NHS staff and cancer charity workers (N = 31). Interviews with cancer survivors highlighted barriers to engagement, such as concerns about physical activity worsening fatigue. Focus groups highlighted concerns about support appointment length and how to support distressed participants. Feedback informed intervention modifications, to maximise acceptability, feasibility and likelihood of behaviour change. Our systematic method for understanding user views enabled us to anticipate and address important barriers to engagement. This methodology may be useful to others developing digital interventions.

Systematic characterization of BAF mutations provides insights into intracomplex synthetic lethalities in human cancers.

Aberrations in genes coding for subunits of the BRG1/BRM associated factor (BAF) chromatin remodeling complexes are highly abundant in human cancers. Currently, it is not understood how these mostly loss-of-function mutations contribute to cancer development and how they can be targeted therapeutically. The cancer-type-specific occurrence patterns of certain subunit mutations suggest subunit-specific effects on BAF complex function, possibly by the formation of aberrant residual complexes. Here, we systematically characterize the effects of individual subunit loss on complex composition, chromatin accessibility and gene expression in a panel of knockout cell lines deficient for 22 BAF subunits. We observe strong, specific and sometimes discordant alterations dependent on the targeted subunit and show that these explain intracomplex codependencies, including the synthetic lethal interactions SMARCA4-ARID2, SMARCA4-ACTB and SMARCC1-SMARCC2. These data provide insights into the role of different BAF subcomplexes in genome-wide chromatin organization and suggest approaches to therapeutically target BAF-mutant cancers.

Proteases Underground: Analysis of the Maize Root Apoplast Identifies Organ Specific Papain-Like Cysteine Protease Activity.

Plant proteases are key regulators of plant cell processes such as seed development, immune responses, senescence and programmed cell death (PCD). Apoplastic papain-like cysteine proteases (PL) are hubs in plant-microbe interactions and play an important role during abiotic stresses. The apoplast is a crucial interface for the interaction between plant and microbes. So far, apoplastic maize PL and their function have been mostly described for aerial parts. In this study, we focused on apoplastic PLCPs in the roots of maize plants. We have analyzed the phylogeny of maize PLCPs and investigated their protein abundance after salicylic acid (SA) treatment. Using activity-based protein profiling (ABPP) we have identified a novel root-specific PLCP belonging to the RD21-like subfamily, as well as three SA activated PLCPs. The root specific PLCP CP1C shares sequence and structural similarities to known CP1-like proteases. Biochemical analysis of recombinant CP1C revealed different substrate specificities and inhibitor affinities compared to the related proteases. This study characterized a root-specific PLCP and identifies differences between the SA-dependent activation of PLCPs in roots and leaves.

MTHFD1 interaction with BRD4 links folate metabolism to transcriptional regulation.

The histone acetyl reader bromodomain-containing protein 4 (BRD4) is an important regulator of chromatin structure and transcription, yet factors modulating its activity have remained elusive. Here we describe two complementary screens for genetic and physical interactors of BRD4, which converge on the folate pathway enzyme MTHFD1 (methylenetetrahydrofolate dehydrogenase, cyclohydrolase and formyltetrahydrofolate synthetase 1). We show that a fraction of MTHFD1 resides in the nucleus, where it is recruited to distinct genomic loci by direct interaction with BRD4. Inhibition of either BRD4 or MTHFD1 results in similar changes in nuclear metabolite composition and gene expression; pharmacological inhibitors of the two pathways synergize to impair cancer cell viability in vitro and in vivo. Our finding that MTHFD1 and other metabolic enzymes are chromatin associated suggests a direct role for nuclear metabolism in the control of gene expression.

Renewed: Protocol for a randomised controlled trial of a digital intervention to support quality of life in cancer survivors.

INTRODUCTION: Low quality of life is common in cancer survivors. Increasing physical activity, improving diet, supporting psychological well-being and weight loss can improve quality of life in several cancers and may limit relapse. The aim of the randomised controlled trial outlined in this protocol is to examine whether a digital intervention (Renewed), with or without human support, can improve quality of life in cancer survivors. Renewed provides support for increasing physical activity, managing difficult emotions, eating a healthier diet and weight management. METHODS AND ANALYSIS: A randomised controlled trial is being conducted comparing usual care, access to Renewed or access to Renewed with brief human support. Cancer survivors who have had colorectal, breast or prostate cancer will be identified and invited through general practice searches and mail-outs. Participants are asked to complete baseline measures immediately after screening and will then be randomised to a study group; this is all completed on the Renewed website. The primary outcome is quality of life measured by the European Organization for Research and Treatment of Cancer QLQ-c30. Secondary outcomes include anxiety and depression, fear of cancer recurrence, general well-being, enablement and items relating to costs for a health economics analysis. Process measures include perceptions of human support, intervention usage and satisfaction, and adherence to behavioural changes. Qualitative process evaluations will be conducted with patients and healthcare staff providing support. ETHICS AND DISSEMINATION: The trial has been approved by the NHS Research Ethics Committee (Reference 18/NW/0013). The results of this trial will be published in peer-reviewed journals and through conference presentations. TRIAL REGISTRATION NUMBER: ISRCTN96374224; Pre-results.

Homolog-Selective Degradation as a Strategy to Probe the Function of CDK6 in AML.

The design of selective small molecules is often stymied by similar ligand binding pockets. Here, we report BSJ-03-123, a phthalimide-based degrader that exploits protein-interface determinants to achieve proteome-wide selectivity for the degradation of cyclin-dependent kinase 6 (CDK6). Pharmacologic CDK6 degradation targets a selective dependency of acute myeloid leukemia cells, and transcriptomics and phosphoproteomics profiling of acute degradation of CDK6 enabled dynamic mapping of its immediate role in coordinating signaling and transcription.

LZTR1 is a regulator of RAS ubiquitination and signaling.

In genetic screens aimed at understanding drug resistance mechanisms in chronic myeloid leukemia cells, inactivation of the cullin 3 adapter protein-encoding leucine zipper-like transcription regulator 1 (LZTR1) gene led to enhanced mitogen-activated protein kinase (MAPK) pathway activity and reduced sensitivity to tyrosine kinase inhibitors. Knockdown of the Drosophila LZTR1 ortholog CG3711 resulted in a Ras-dependent gain-of-function phenotype. Endogenous human LZTR1 associates with the main RAS isoforms. Inactivation of LZTR1 led to decreased ubiquitination and enhanced plasma membrane localization of endogenous KRAS (V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog). We propose that LZTR1 acts as a conserved regulator of RAS ubiquitination and MAPK pathway activation. Because LZTR1 disease mutations failed to revert loss-of-function phenotypes, our findings provide a molecular rationale for LZTR1 involvement in a variety of inherited and acquired human disorders.