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Targeting the PI3K-AKT-mTOR pathway is a promising therapeutic strategy for breast cancer treatment. However, low response rates and development of resistance to PI3K-AKT-mTOR inhibitors remain major clinical challenges. Here, we show that MYC activation drives resistance to mTOR inhibitors (mTORi) in breast cancer. Multiomic profiling of mouse invasive lobular carcinoma (ILC) tumors revealed recurrent Myc amplifications in tumors that acquired resistance to the mTORi AZD8055. MYC activation was associated with biological processes linked to mTORi response and counteracted mTORi-induced translation inhibition by promoting translation of ribosomal proteins. In vitro and in vivo induction of MYC conferred mTORi resistance in mouse and human breast cancer models. Conversely, AZD8055-resistant ILC cells depended on MYC, as demonstrated by the synergistic effects of mTORi and MYCi combination treatment. Notably, MYC status was significantly associated with poor response to everolimus therapy in metastatic breast cancer patients. Thus, MYC is a clinically relevant driver of mTORi resistance that may stratify breast cancer patients for mTOR-targeted therapies., (© 2023 Bhin et al.)

Importance: In ERBB2 (formerly HER2)-positive metastatic breast cancer (MBC), combining trastuzumab and pertuzumab with taxane-based chemotherapy is the first line of standard care. Given that trastuzumab plus pertuzumab was proven effective in ERBB2-positive MBC, even without chemotherapy, whether the optimal first-line strategy could be trastuzumab plus pertuzumab alone instead of with chemotherapy is unresolved., Objective: To assess overall survival (OS) at 2 years and progression-free survival (PFS) for patients randomly assigned to receive first-line pertuzumab plus trastuzumab alone or with chemotherapy followed by trastuzumab and emtansine at progression; PFS of second-line trastuzumab and emtansine treatment following trastuzumab plus pertuzumab; and OS and PFS in the ERBB2-enriched and ERBB2-nonenriched subtypes., Design, Setting, and Participants: This was a secondary analysis of a multicenter, open-label, phase 2 randomized clinical trial conducted at 27 sites in France, 20 sites in Switzerland, 9 sites in the Netherlands, and 1 site in Germany. Overall, 210 patients with centrally confirmed ERBB2-positive MBC were randomized between May 3, 2013, and January 4, 2016, with termination of the trial May 26, 2020. Data were analyzed from December 18, 2020, to May 10, 2022., Interventions: Patients randomly received pertuzumab (840 mg intravenously [IV], then 420 mg IV every 3 weeks) plus trastuzumab (8 mg/kg IV, then 6 mg/kg IV every 3 weeks) without chemotherapy (group A) or pertuzumab plus trastuzumab (same doses) with either paclitaxel (90 mg/m2 for days 1, 8, and 15, then every 4 weeks for ≥4 months) or vinorelbine tartrate (25 mg/m2 for first administration followed by 30 mg/m2 on days 1 and 8 and every 3 weeks for ≥4 months) followed by pertuzumab plus trastuzumab maintenance after chemotherapy discontinuation (group B)., Main Outcomes and Measures: Overall survival at 24 months by treatment group, PFS for first-line treatment, PFS for second-line treatment, and patient-reported quality of life (QOL)., Results: A total of 210 patients were included in the analysis, with a median age of 58 (range, 26-85) years. For group A, 24-month OS was 79.0% (90% CI, 71.4%-85.4%); for group B, 78.1% (90% CI, 70.4%-84.5%). Median PFS with first-line treatment was 8.4 (95% CI, 7.9-12.0) months in group A and 23.3 (95% CI, 18.9-33.1) months in group B. Unlike expectations, OS and PFS did not markedly differ between populations with ERBB2-enriched and ERBB2-nonenriched cancer. Adverse events were less common without chemotherapy, with small QOL improvements from baseline in group A and stable QOL in group B., Conclusions and Relevance: The findings of this secondary analysis of a randomized clinical trial suggest that the chemotherapy-free anti-ERBB2 strategy is feasible without being detrimental in terms of OS. The 50-gene prediction analysis of microarray signature could not help to identify the most appropriate patient population for this approach., Trial Registration: ClinicalTrials.gov Identifier: NCT01835236.

Performing successful adaptive behaviour relies on our ability to process a wide range of temporal intervals with certain precision. Studies on the role of the cerebellum in temporal information processing have adopted the dogma that the cerebellum is involved in sub-second processing. However, emerging evidence shows that the cerebellum might be involved in suprasecond temporal processing as well. Here we review the reciprocal loops between cerebellum and cerebral cortex and provide a theoretical account of cerebro-cerebellar interactions with a focus on how cerebellar output can modulate cerebral processing during learning of complex sequences. Finally, we propose that while the ability of the cerebellum to support millisecond timescales might be intrinsic to cerebellar circuitry, the ability to support supra-second timescales might result from cerebellar interactions with other brain regions, such as the prefrontal cortex., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Boven and Cerminara.)

Background: ESR1 mutations have been identified as mechanism for endocrine resistance and are also associated with a decreased overall survival. We assessed ESR1 mutations in circulating tumor DNA (ctDNA) for impact on outcome to taxane-based chemotherapy in advanced breast cancer patients., Methods: ESR1 mutations were determined in archived plasma samples from patients treated with paclitaxel and bevacizumab (AT arm, N = 91) in the randomized phase II ATX study. Samples collected at baseline (n = 51) and at cycle 2 (n = 13, C2) were analyzed using a breast cancer next-generation sequencing panel. This study was powered to detect a benefit in progression-free survival (PFS) at six months for patients treated with paclitaxel/bevacizumab compared to historical trials with fulvestrant. PFS, overall survival (OS), and ctDNA dynamics were exploratory analyses., Results: PFS at six months was 86% (18/21) in patients with an ESR1 mutation detected and 85% (23/27) in wildtype ESR1 patients. In our exploratory analysis, median progression-free survival (PFS) was 8.2 months [95% CI, 7.6-8.8] for ESR1 mutant patients versus 8.7 months [95% confidence interval (CI), 8.3-9.2] for ESR1 wildtype patients [p = 0.47]. The median overall survival (OS) was 20.7 months [95% CI, 6.6-33.7] for ESR1 mutant patients versus 28.1 months [95% confidence interval (CI), 19.3-36.9] for ESR1 wildtype patients [p = 0.27]. Patients with ≥ two ESR1 mutations had a significantly worse OS, but not PFS, compared to those who did not [p = 0.003]. Change in ctDNA level at C2 was not different between ESR1 and other mutations., Conclusions: Presence of ESR1 mutations in baseline ctDNA might not be associated with inferior PFS and OS in advanced breast cancer patients treated with paclitaxel/bevacizumab., (© 2023. The Author(s).)

Behavioural feedback is critical for learning in the cerebral cortex. However, such feedback is often not readily available. How the cerebral cortex learns efficiently despite the sparse nature of feedback remains unclear. Inspired by recent deep learning algorithms, we introduce a systems-level computational model of cerebro-cerebellar interactions. In this model a cerebral recurrent network receives feedback predictions from a cerebellar network, thereby decoupling learning in cerebral networks from future feedback. When trained in a simple sensorimotor task the model shows faster learning and reduced dysmetria-like behaviours, in line with the widely observed functional impact of the cerebellum. Next, we demonstrate that these results generalise to more complex motor and cognitive tasks. Finally, the model makes several experimentally testable predictions regarding cerebro-cerebellar task-specific representations over learning, task-specific benefits of cerebellar predictions and the differential impact of cerebellar and inferior olive lesions. Overall, our work offers a theoretical framework of cerebro-cerebellar networks as feedback decoupling machines., (© 2023. The Author(s).)

Primary sensory cortex is thought to process incoming sensory information, while decision variables important for driving behavior are assumed to arise downstream in the processing hierarchy. Here, we used population two-photon calcium imaging and targeted two-photon optogenetic stimulation of neurons in layer 2/3 of mouse primary somatosensory cortex (S1) during a texture discrimination task to test for the presence of decision signals and probe their behavioral relevance. Small but distinct populations of neurons carried information about the stimulus irrespective of the behavioral outcome (stimulus neurons), or about the choice irrespective of the presented stimulus (decision neurons). Decision neurons show categorical coding that develops during learning, and lack a conclusive decision signal in Miss trials. All-optical photostimulation of decision neurons during behavior improves behavioral performance, establishing a causal role in driving behavior. The fact that stimulus and decision neurons are intermingled challenges the idea of S1 as a purely sensory area, and causal perturbation suggests a direct involvement of S1 decision neurons in the decision-making process., (© 2022. The Author(s), under exclusive licence to Springer Nature America, Inc.)

Individual response to sunitinib in metastatic renal cell carcinoma (mRCC) patients is highly variable. Earlier, sunitinib outcome was related to single nucleotide polymorphisms (SNPs) in CYP3A5 and ABCB1. Our aim is to provide novel insights into biological mechanisms underlying sunitinib action. We included mRCC patients from the European EuroTARGET consortium (n = 550) and the RIKEN cohort in Japan (n = 204) which were analysed separately and in a meta-analysis of genome-wide association studies (GWAS). SNPs were tested for association with progression-free survival (PFS) and overall survival (OS) using Cox regression. Summary statistics were combined using a fixed effect meta-analysis. SNP rs28520013 in PDLIM3 and the correlated SNPs rs2205096 and rs111356738 both in DSCAM, showed genome-wide significance (p < 5 × 10−8) with PFS and OS in the meta-analysis. The variant T-allele of rs28520013 associated with an inferior PFS of 5.1 months compared to 12.5 months in non-carriers (p = 4.02 × 10−10, HR = 7.26). T-allele carriers of rs28520013 showed an inferior OS of 6.9 months versus 30.2 months in non-carriers (p = 1.62 × 10−8, HR = 5.96). In this GWAS we identified novel genetic variants in PDLIM3 and DSCAM that impact PFS and OS in mRCC patients receiving sunitinib. The underlying link between the identified genes and the molecular mechanisms of sunitinib action needs to be elucidated.