ARAF protein kinase activates RAS by antagonizing its binding to RASGAP NF1.

RAF protein kinases are effectors of the GTP-bound form of small guanosine triphosphatase RAS and function by phosphorylating MEK. We showed here that the expression of ARAF activated RAS in a kinase-independent manner. Binding of ARAF to RAS displaced the GTPase-activating protein NF1 and antagonized NF1-mediated inhibition of RAS. This reduced ERK-dependent inhibition of RAS and increased RAS-GTP. By this mechanism, ARAF regulated the duration and consequences of RTK-induced RAS activation and supported the RAS output of RTK-dependent tumor cells. In human lung cancers with EGFR mutation, amplification of ARAF was associated with acquired resistance to EGFR inhibitors, which was overcome by combining EGFR inhibitors with an inhibitor of the protein tyrosine phosphatase SHP2 to enhance inhibition of nucleotide exchange and RAS activation.

Ibrutinib and venetoclax as primary therapy in symptomatic, treatment-naïve Waldenström macroglobulinemia.

ABSTRACT: Concurrent Bruton tyrosine kinase and BCL2 inhibition has not yet been investigated in Waldenström macroglobulinemia (WM). We performed an investigator-initiated trial of ibrutinib and venetoclax in symptomatic treatment-naïve patients with MYD88-mutated WM. Patients received ibrutinib 420 mg once daily (cycle 1), followed by a ramp-up of venetoclax to 400 mg daily (cycle 2). The combination was then administered for 22 additional 4-week cycles. The attainment of very good partial response (VGPR) was the primary end point. Forty-five patients were enrolled in this study. The median baseline characteristics were as follows: age 67 years, serum IgM 43 g/L, and hemoglobin 102 g/L. Seventeen patients (38%) carried CXCR4 mutations. Nineteen patients (42%) achieved VGPR. Grade 3 or higher adverse events included neutropenia (38%), mucositis (9%), and tumor lysis syndrome (7%). Atrial fibrillation occurred in 3 (9%), and ventricular arrhythmia in 4 (9%) patients that included 2 grade 5 events. With a median follow-up of 24.4 months, the 24-month progression-free survival (PFS) and overall survival (OS) rates were 76% and 96%, respectively, and were not impacted by CXCR4 mutations. The median time on therapy was 10.2 months, and the median time after the end of therapy (EOT) was 13.3 months. Eleven of the 12 progression events occurred after EOT, and the 12-month PFS rates after EOT were 79%; 93% if VGPR was attained, and 69% for other patients (P = .12). Ibrutinib and venetoclax induced high VGPR rates and durable responses after EOT, although they were associated with a higher-than-expected rate of ventricular arrhythmia in patients with WM, leading to early study treatment termination. This trial was registered at www.clinicaltrials.gov as #NCT04273139.

Dose reductions in patients with Waldenström macroglobulinaemia treated with ibrutinib.

Waldenström macroglobulinaemia (WM) is characterized by the presence of a MYD88L265P mutation. This mutation promotes growth and survival of malignant cells through Bruton tyrosine kinase (BTK) activation. Ibrutinib was the first BTK inhibitor approved for WM. Intolerance to ibrutinib frequently leads to dose reductions, though the impact of reducing ibrutinib dosing has not been systematically studied. We performed a retrospective study to determine the frequency and impact of reducing ibrutinib dosing in WM patients. With a median treatment time of 64 months, 96 (27%) of 353 WM patients required a dose reduction due to adverse events such as musculoskeletal symptoms, cardiac events, dermatologic symptoms, cytopenias, and gastrointestinal symptoms. The median time to initial dose reduction was 9.3 months (range, 0.5-74). Dose reductions were more common in those 65 years of age or older versus under 65 [hazard ratio (HR) 2.46, 95% confidence interval (CI) 1.55-3.90; p < 0.001], and in females versus males (HR 2.20, 95% CI 1.41-3.28, p < 0.001). Most patients (65%) had improvement or resolution of adverse effects after initial dose reduction. With a median follow-up of three years from dose reduction, hematologic response sustained or deepened in 79% of patients. These data suggest that dose reduction of ibrutinib is a reasonable treatment approach for patients with intolerable side effects.

Analysis of the illicit tobacco market in Georgia in response to fiscal and non-fiscal tobacco control measures.

BACKGROUND: Georgian illicit cigarette consumption was 1.5% in 2017. In 2018, a new tobacco control law took effect followed by a substantial cigarette excise tax increase in 2019. Research shows these policies reduce tobacco consumption, but the tobacco industry argues they increase illicit trade. There is limited evidence on this, particularly from developing countries. METHODS: A panel household survey in Georgia obtained data over three waves: 2017 baseline, 2018 after the tobacco control law took effect and 2019 after taxes increased. A sample of 1578 smokers (and quitters in later waves) from five regions reported their tobacco use and were asked to present a cigarette pack in their possession. These were examined for tax stamps and health warnings to establish legality. FINDINGS: There was no evidence of an increase in illicit cigarette consumption in Tbilisi, Kutaisi, Akhaltsikhe or Gori in any wave. In Zugdidi, near the Russian-occupied Abkhazia, illicit cigarette consumption was increasing even prior to the tax increase, reaching 30.9% by wave 3. A country-wide shift occurred from manufactured cigarettes to roll-your-own tobacco (whose tax remained unchanged) between waves 2 and 3. CONCLUSION: No evidence of a country-wide increase in illicit cigarette trade was found after non-fiscal tobacco measures took effect and cigarette taxes increased. Relatively high illicit cigarette consumption in Zugdidi highlights the role of disputed territories and border administration in illicit cigarette supply. Substitution towards roll-your-own tobacco after manufactured cigarette taxes increased demonstrates the importance of equalising taxes on tobacco products to maximise public health benefits.

Illicit tobacco trade in Georgia: prevalence and perceptions.

BACKGROUND: In lower-income and middle-income countries, limited research exists on illicit tobacco trade and its responsiveness to taxation. Tobacco taxes are critical in reducing tobacco consumption, thereby improving public health. However, the tobacco industry claims that tax increases will increase illicit tobacco trade. Therefore, research evidence on the size of the illicit cigarette market is needed in Georgia and other low-income and middle-income countries to inform tobacco tax policies. METHODS: In 2017, a household survey using stratified multistage sampling was conducted in Georgia with 2997 smokers, to assess illicit tobacco consumption. Smokers were asked to show available cigarette packs to the surveyors. These were examined for tax stamps and health warnings which allowed for an assessment of illegal cigarette consumption in Georgia. FINDINGS: The packs shown to surveyors suggest illicit cigarette trade is low (1.5%), although with regional differences, as illicit cigarette packs were present in 6% of the households in Zugdidi. Most illicit cigarettes were purchased at kiosks or informal outlets. This estimate might be conservative, as 28% of respondents did not show any packs to the surveyors. CONCLUSIONS: Despite recent tobacco tax increases, illicit cigarette trade in Georgia seems to be negligible. The market is more vulnerable to illicit cigarette trade close to the border with Abkhazia (near Zugdidi). Tighter control or ban of tobacco sales at kiosks and informal outlets may reduce illicit cigarette trade. Further investigation is planned to better understand why a large proportion of survey participants said they had no pack available at home.

Mercury in little brown bat (Myotis lucifugus) maternity colonies and its correlation with freshwater acidity in Nova Scotia, Canada.

Insectivorous little brown bats are exposed to elevated concentrations of mercury (Hg) through their preference for aquatic-based prey. Here we investigated spatial patterns of total Hg (THg) in fur from 10 little brown bat maternity colonies across Nova Scotia, and assessed relationships with the acidity of nearby lakes and rivers. Total Hg concentrations were measured in fur samples from 149 adult female little brown bats. Values showed significant variation among colonies (mean range 3.76-27.38 µg/g, dry weight), and 48% of individuals had Hg concentrations in excess of the 10 µg/g threshold associated with neurochemical changes in Chiroptera conspecifics (n = 26) from Virginia. Average surface water acidity parameters (pH and acid neutralization capacity) within an 8 km radius of each maternity roost showed strong negative associations with average colony fur THg concentrations. This suggests that freshwater acidity in foraging grounds explains much of the variation in average fur THg concentrations in little brown bat colonies. These findings highlight the significant role that water quality may have on Hg bioaccumulation within terrestrial species that feed on aquatic prey.

Direct beam radiation exposure to surgeons during pinning of supracondylar humerus fractures: does C-arm position and the attending surgeon matter?

BACKGROUND: Direct beam radiation exposure to the surgeon, especially to their hands, is extremely common during supracondylar humerus fracture pinnings and results in exposure to significantly greater doses of ionizing radiation when compared with scatter radiation. The purpose of this study was to determine how often surgeons are exposed to direct beam radiation during this surgery and whether the C-arm position and the surgeon's experience influence radiation exposure. METHODS: In this double blind study, we collected 3842 fluoroscopic still images from 78 closed reduction and percutaneous pinning surgeries for supracondylar humerus fractures performed or supervised by 6 attending surgeons. The percentage of images containing a surgeon's body was calculated as an indicator of direct beam radiation exposure. Total fluoroscopy time, C-arm position (standard or inverted), and whether the primary surgeon was an attending, resident, or both were recorded. Nonparametric statistical analyses were performed. RESULTS: Fluoroscopy lasted for a median of 34 seconds, and the surgeon was exposed to direct beam radiation in a median of 13% of fluoroscopy films, with exposure ranging from 0% to 97% per surgery. Fluoroscopy was significantly longer when the C-arm position was inverted when compared with the standard position (43 vs. 26 s, P=0.034). Surgeons' exposure to direct beam radiation was also slightly greater when the C-arm position was inverted (16% vs. 10%, P=0.087). The duration of fluoroscopy exposure and the percentage of films with the body exposed to radiation did not differ based on whether the surgery was performed by an attending, a resident, or both (P=0.53 and 0.28, respectively). However, the percentage of films with bodily radiation exposure did significantly differ between the attending physicians (P=0.029). CONCLUSIONS: Direct beam radiation exposure varied widely between surgeries and surgeons, ranging from none to nearly constant exposure. Surgical time also significantly increased with the C-arm in the inverted position compared with the standard position. Given the significant variation in exposure between attending physicians, it is likely that exposure to direct beam radiation can be avoided with improved awareness about the risk of direct beam radiation exposure and cautious surgical technique. LEVEL OF EVIDENCE: Not applicable.

Rationale, formative research, and protocol for Calma, Conversa, y Cría: A pilot mindful parenting intervention with Latina women.

Background: Latina mothers' stress is associated with their children's health behaviors and risk for obesity; however, existing pediatric health promotion programs have not focused on maternal stress reduction. Methods: Herein we describe a study design that will examine the acceptability and feasibility of Calma, Conversa, y Cría (CCC) a 6-week mindful parenting intervention designed to reduce stress. We present the results of qualitative research with Latina mothers and experts in Latinx health and mindfulness who provided culturally-relevant feedback on existing mindful parenting strategies to inform the development of CCC. Fifty Latina mothers of children ages 3-11 years will be randomly assigned to CCC or an enhanced usual care health education intervention. Acceptability will be assessed through participant satisfaction surveys and exit interviews. Feasibility will be determined through detailed tracking of recruitment, retention, and attendance rates. A signal regarding any group differences in maternal stress, health-related parenting practices, child diet, child physical activity, and child quality of life will be explored. Discussion: The development of interventions that can reduce maternal stress and risk for obesity in Latinx children is critical to significantly reduce negative health impacts in this underserved population. Our approach includes the identification of effective cultural adaptations that should improve the feasibility and acceptability of mindful parenting strategies in Latinx families, ideally reducing maternal stress and improving parenting behaviors related to child health. If successful, CCC will be examined in a larger efficacy trial involving the measurement of objective biomarkers of children's chronic disease risk.

A pilot study on dasatinib in patients with Waldenström macroglobulinemia progressing on ibrutinib.

The hematopoietic cell kinase (HCK) regulates BTK activation and represents a potential therapeutic target in Waldenstrom macroglobulinemia (WM). We investigated dasatinib, a potent HCK inhibitor, in patients with WM progressing on ibrutinib. Study treatment consisted of dasatinib administered at 100 mg by mouth once daily in four-week cycles for up to 24 cycles. This study was registered under ClinicalTrials.Gov ID NCT04115059. Three participants were enrolled and received at least one cycle of dasatinib. The best response was stable disease. Two patients received 5 months and one patient received 1 month of therapy. The dose of dasatinib was decreased in one participant due to volume overload. Based on the lack of responses observed, the study was terminated. Dasatinib might not be effective in patients with WM progressing on ibrutinib.

MAPK pathway activation selectively inhibits ASCL1-driven small cell lung cancer.

Activation of mitogenic signaling pathways is a common oncogenic driver of many solid tumors including lung cancer. Although activating mutations in the mitogen-activated protein kinase (MAPK) pathway are prevalent in non-small cell lung cancers, MAPK pathway activity, counterintuitively, is relatively suppressed in the more aggressively proliferative small cell lung cancer (SCLC). Here, we elucidate the role of the MAPK pathway and how it interacts with other signaling pathways in SCLC. We find that the most common SCLC subtype, SCLC-A associated with high expression of ASCL1, is selectively sensitive to MAPK activation in vitro and in vivo through induction of cell-cycle arrest and senescence. We show strong upregulation of ERK negative feedback regulators and STAT signaling upon MAPK activation in SCLC-A lines. These findings provide insight into the complexity of signaling networks in SCLC and suggest subtype-specific mitogenic vulnerabilities.

HER2-Mediated Internalization of Cytotoxic Agents in ERBB2 Amplified or Mutant Lung Cancers.

Amplification of and oncogenic mutations in ERBB2, the gene encoding the HER2 receptor tyrosine kinase, promote receptor hyperactivation and tumor growth. Here we demonstrate that HER2 ubiquitination and internalization, rather than its overexpression, are key mechanisms underlying endocytosis and consequent efficacy of the anti-HER2 antibody-drug conjugates (ADC) ado-trastuzumab emtansine (T-DM1) and trastuzumab deruxtecan (T-DXd) in lung cancer cell lines and patient-derived xenograft models. These data translated into a 51% response rate in a clinical trial of T-DM1 in 49 patients with ERBB2-amplified or -mutant lung cancers. We show that cotreatment with irreversible pan-HER inhibitors enhances receptor ubiquitination and consequent ADC internalization and efficacy. We also demonstrate that ADC switching to T-DXd, which harbors a different cytotoxic payload, achieves durable responses in a patient with lung cancer and corresponding xenograft model developing resistance to T-DM1. Our findings may help guide future clinical trials and expand the field of ADC as cancer therapy. SIGNIFICANCE: T-DM1 is clinically effective in lung cancers with amplification of or mutations in ERBB2. This activity is enhanced by cotreatment with irreversible pan-HER inhibitors, or ADC switching to T-DXd. These results may help address unmet needs of patients with HER2-activated tumors and no approved targeted therapy.See related commentary by Rolfo and Russo, p. 643.This article is highlighted in the In This Issue feature, p. 627.

Distribution of mercury in archived fur from little brown bats across Atlantic Canada.

Total mercury (Hg) concentrations were measured in archived fur from adult female little brown bats sampled at maternity roosts across Atlantic Canada. Mercury concentrations varied significantly among regions and roosts. Bats from Nova Scotia and Newfoundland had the highest median Hg concentrations (9.67 µg/g and 9.51 µg/g) among regions, and individuals from Kejimkujik National Park had the highest Hg (median: 28.38 µg/g) among roosts. Over one third of individuals sampled had fur Hg concentrations exceeding thresholds associated with neurochemical responses. Within-roost examinations of stable carbon and nitrogen isotopes in fur showed inconsistent associations with Hg concentrations. Therefore, the hypothesis that within-roost variation in Hg is driven by variation in diet is not supported by this data, and it is recommended that key prey items be included in future mercury bioaccumulation studies for bats. The elevated mercury fur concentrations for bats from southern Nova Scotia remains an anomaly of concern even when placed in the larger context of Atlantic Canada.