Oncogenic RET fusions occur in diverse cancers. Pralsetinib is a potent, selective inhibitor of RET receptor tyrosine kinase. ARROW (NCT03037385, ongoing) was designed to evaluate pralsetinib efficacy and safety in patients with advanced RET-altered solid tumors. Twenty-nine patients with 12 different RET fusion–positive solid tumor types, excluding non-small-cell lung cancer and thyroid cancer, who had previously received or were not candidates for standard therapies, were enrolled. The most common RET fusion partners in 23 efficacy-evaluable patients were CCDC6 (26%), KIF5B (26%) and NCOA4 (13%). Overall response rate, the primary endpoint, was 57% (95% confidence interval, 35–77) among these patients. Responses were observed regardless of tumor type or RET fusion partner. Median duration of response, progression-free survival and overall survival were 12 months, 7 months and 14 months, respectively. The most common grade ≥3 treatment-related adverse events were neutropenia (31%) and anemia (14%). These data validate RET as a tissue-agnostic target with sensitivity to RET inhibition, indicating pralsetinib’s potential as a well-tolerated treatment option with rapid, robust and durable anti-tumor activity in patients with diverse RET fusion–positive solid tumors.

Growth plate abnormalities, associated with impaired hypertrophic chondrocyte apoptosis, are observed in humans and animals with abnormalities of vitamin D action and renal phosphate reabsorption. Low circulating phosphate levels impair hypertrophic chondrocyte apoptosis, whereas treatment of these cells with phosphate activates the mitochondrial apoptotic pathway. Because phosphate-mediated apoptosis of chondrocytes is differentiation-dependent, studies were performed to identify factors that contribute to hypertrophic chondrocyte apoptosis. An increase in the percentage of cells with low mitochondrial membrane potential, evaluated by JC-1 fluorescence, was observed during hypertrophic differentiation of primary murine chondrocytes in culture. This percentage was further increased by treatment of hypertrophic, but not proliferative, chondrocytes with phosphate. Phosphate-mediated apoptosis was observed as early as 30 min post-treatment and was dependent upon Erk1/2 phosphorylation. Inhibition of Erk1/2 phosphorylation in vivo confirmed an important role for this signaling pathway in regulating hypertrophic chondrocyte apoptosis in growing mice. Murine embryonic metatarsals cultured under phosphate-restricted conditions demonstrated a 2.5-fold increase in parathyroid hormone-related protein mRNA expression accompanied by a marked attenuation in phospho-Erk immunoreactivity in hypertrophic chondrocytes. Thus, these investigations point to an important role for phosphate in regulating mitochondrial membrane potential in hypertrophic chondrocytes and growth plate maturation by the parathyroid hormone-related protein signaling pathway.Maturation of the growth of long bones is dependent upon the differentiation of proliferative chondrocytes into prehypertrophic and subsequently hypertrophic chondrocytes. Terminal differentiation of hypertrophic chondrocytes is characterized by the expression of signaling molecules that promote vascular invasion, apoptosis, and replacement of hypertrophic chondrocytes by osteoblasts that lay down the primary spongiosa of bone. Aberrant regulation of this developmental process results in growth plate disorders. Although calcium has been shown to play an important role in regulating chondrocyte maturation (1), apoptosis of terminally differentiated hypertrophic chondrocytes is dependent upon normal levels of circulating phosphate (2).Rickets is a growth plate anomaly observed in growing animals and humans with abnormalities of vitamin D action and renal phosphate reabsorption (3-6). In vivo investigations in genetically modified and dietary-manipulated mouse models demonstrate that hypophosphatemia is the underlying metabolic abnormality that impairs growth plate maturation in these disorders: low circulating phosphate levels result in impaired apoptosis of terminally differentiated hypertrophic chondrocytes in the growth plate, leading to rickets (2). The observation that inhibition of phosphate transport prevents phosphate-mediated apoptosis in hypertrophic chondrocytes (7-9) further ...

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While epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have changed the treatment landscape for EGFR mutant (L858R and ex19del)-driven non-small-cell lung cancer (NSCLC), most patients will eventually develop resistance to TKIs. In the case of first- and second-generation TKIs, up to 60% of patients will develop an EGFR T790M mutation, while third-generation irreversible TKIs, like osimertinib, lead to C797S as the primary on-target resistance mutation. The development of reversible inhibitors of these resistance mutants is often hampered by poor selectivity against wild-type EGFR, resulting in potentially dose-limiting toxicities and a sub-optimal profile for use in combinations. BLU-945 (compound 30 ) is a potent, reversible, wild-type-sparing inhibitor of EGFR+/T790M and EGFR+/T790M/C797S resistance mutants that maintains activity against the sensitizing mutations, especially L858R. Pre-clinical efficacy and safety studies supported progression of BLU-945 into clinical studies, and it is currently in phase 1/2 clinical trials for treatment-resistant EGFR-driven NSCLC.

Phosphate and parathyroid hormone related peptide (PTHrP) are required for normal growth plate maturation. Hypophosphatemia impairs hypertrophic chondrocyte apoptosis leading to rachitic expansion of the growth plate; however, the effect of phosphate restriction on chondrocyte differentiation during endochondral bone formation has not been examined. Investigations were, therefore, undertaken to address whether phosphate restriction alters the maturation of embryonic d15.5 murine metatarsal elements. Metatarsals cultured in low phosphate media exhibited impaired chondrocyte differentiation, analogous to that seen with PTHrP-treatment of metatarsals cultured in control media. Because phosphate restriction acutely increases PTHrP expression in cultured metatarsals, studies were undertaken to determine if this increase in PTHrP plays a pathogenic role in the impaired chondrocyte differentiation observed under low phosphate conditions. In contrast to what was observed with wild-type metatarsal elements, phosphate restriction did not impair the differentiation of metatarsals isolated from PTHrP heterozygous or PTHrP knockout mice. In vivo studies in postnatal mice demonstrated that PTHrP haploinsufficiency also prevents the impaired hypertrophic chondrocyte apoptosis observed with phosphate restriction. To determine how signaling through the PTH/PTHrP receptor antagonizes the pro-apoptotic effects of phosphate, investigations were performed in primary murine hypertrophic chondrocytes. Receptor activation impaired phosphate-induced Erk1/2 phosphorylation specifically in the mitochondrial fraction and decreased levels of mitochondrial Bad, while increasing cytosolic phospho-Bad. Thus, these data demonstrate that phosphate restriction attenuates chondrocyte differentiation as well as impairing hypertrophic chondrocyte apoptosis and implicate a functional role for the PTH/PTHrP signaling pathway in the abnormalities in chondrocyte differentiation and hypertrophic chondrocyte apoptosis observed under phosphate restricted conditions.

) is a corticotropin-releasing factor (CRF)-like peptide whose role in stress is not well characterized. To study the physiological role of UCN1 in the response of the hypothalamic-pituitary-adrenal (HPA) axis to stress, we generated UCN1-knockout (KO) mice and examined their adaptation to repeated restraint and to cold environment. Wild-type (WT) and UCN1-KO animals were restrained hourly for 15 min from 9 AM to 2 PM, and blood samples were obtained for corticosterone measurement. WT animals adapted to repeated restraint with a decreased corticosterone response; the restraint-stimulated corticosterone levels fell from 215 Ϯ 31 ng/ml in naïve animals to 142 Ϯ 50 ng/ml in mice subjected to repeated restraint (P Ͻ 0.01) and from 552 Ϯ 98 to 314 Ϯ 58 ng/ml (P Ͻ 0.001) in males and females, respectively. Male UCN1-KO mice did not show any adaptation to repeated restraint; instead, restraint-stimulated corticosterone levels were increased from 274 Ϯ 80 ng/ml in naïve animals to 480 Ϯ 75 ng/ml in mice subjected to repeated restraint (P Ͻ 0.001). Female UCN1-KO mice showed only a partial adaptation to repeated restraint, with a decrease in the restraint-stimulated corticosterone response from 631 Ϯ 102 ng/ml in naïve animals to 467 Ϯ 78 ng/ml in mice subjected to repeated restraint (P Ͻ 0.01). In addition, UCN1-KO mice showed no corticosterone response to 2-h cold environment. These data demonstrate an important role for UCN1 in the HPA axis adaptation to repeated restraint and in the corticosterone response to a cold environment. corticosterone; stress; mice CORTICOTROPIN-RELEASING FACTOR (CRF) plays a critical role in the physiology of the central nervous system and the regulation of hypothalamic-pituitary-adrenal (HPA) axis activity. CRF is a 41-amino acid peptide that stimulates the secretion of adrenocorticotropic hormone (ACTH) (28). Several studies (7,14) have shown that CRF is the major regulator of the basal and stress-induced activation of the HPA-axis and is involved in several other physiological and behavioral responses. Three CRF receptors have been characterized: CRFR1, CRFR2, and CRFR3. CRFR1 and CRFR2 have been found in mammalian species (8, 10) and Xenopus (12), whereas CRFR3 has been found only in fish (4). The CRF receptors couple to the stimulatory G protein (G s ), which activates adenylate cyclase, leading to accumulation of cAMP in the target cells. The CRF receptors have also been shown to couple to several other G proteins, such as G i , G q , G o , and G z (9,15). CRF binds to CRFR1 with high affinity and to CRFR2 minimally (24).Recently, three CRF-like peptides, urocortin (UCN)1 (29), UCN2 (25), and UCN3 (20), have been discovered in different species. UCN2 and UCN3 bind to CRFR2 with a high affinity, but only UCN2 can activate CRFR1 at higher concentrations. UCN1 has equal affinity to both receptors (24); however, this peptide binds to CRFR1 with an affinity that is similar to that of CRF. The high-affinity interaction between UCN1 and CRFR1 suggests a physiological role for UCN1 in stress ...

Background: Preclinical data suggest that dual blockade of the insulin-like growth factor-1 receptor (IGF-1R) and HER3 pathways has superior activity to IGF-1R blockade alone in pancreatic ductal adenocarcinoma (PDAC). We tested whether istiratumab, an IGF-1R-and ErbB3-bispecific antibody, can enhance the efficacy of standard of care (SOC) chemotherapy in patients with metastatic PDAC selected for high IGF-1 serum levels. Patients and methods: CARRIE was an international, randomized, double-blind, placebo-controlled phase II study for patients with previously untreated metastatic PDAC. In part 1, 10 patients were evaluated for pharmacokinetics and safety. In part 2, patients with high free serum IGF-1 levels were randomized 1 : 1 to receive either istiratumab [2.8 g intravenously (i.v.) every 2 weeks] or placebo combined with gemcitabine/nabpaclitaxel at approved dose schedule. The co-primary endpoints were progression-free survival (PFS) in patients with high IGF-1 levels and PFS in patients with both high serum IGF-1 levels and heregulin (HRG)þ tumors. Key secondary endpoints were overall survival (OS), objective response rate (ORR) by RECIST v.1.1, and adverse events (AEs) rate. Results: A total of 317 patients were screened, with 88 patients randomized in part 2 (experimental arm n ¼ 43; control n ¼ 45). In the high IGF-1 cohort, median PFS was 3.6 and 7.3 months in the experimental versus control arms, respectively [hazard ratio (HR) ¼ 1.88, P ¼ 0.027]. In the high IGF-1/HRGþ subgroup (n ¼ 44), median PFS was 4.1 and 7.3 months, respectively (HR ¼ 1.39, P ¼ 0.42). Median OS and ORR for the overall population were similar between two arms. No significant difference in serious or grade !3 AEs was observed, although low-grade AEs leading to early discontinuation were higher in the experimental (39.5%) versus control arm (24.4%). Conclusions: Istiratumab failed to improve the efficacy of SOC chemotherapy in this patient setting. High serum IGF-1 levels did not appear to be an adverse prognostic factor when compared with non-biomarker-selected historic controls.

Phosphate is required for terminal differentiation of hypertrophic chondrocytes during postnatal growth plate maturation. In vitro models of chondrocyte differentiation demonstrate that 7mM phosphate, a concentration analogous to that of the late gestational fetus, activates the mitochondrial apoptotic pathway in hypertrophic chondrocytes. This raises the question as to whether extracellular phosphate modulates chondrocyte differentiation and apoptosis during embryonic endochondral bone formation. To address this question, we performed investigations in the mouse metatarsal culture model that recapitulates in vivo bone development. Metatarsals were cultured for 4, 8 and 12 days with 1.25 mM and 7 mM phosphate. Metatarsals cultured with 7 mM phosphate showed a decrease in proliferation compared to those cultured in 1.25 mM phosphate. This decrease in proliferation was accompanied by an early enhancement in hypertrophic chondrocyte differentiation, associated with an increase in FGF18 expression. By 8 days in culture, an increase caspase-9 activation and apoptosis of hypertrophic chondrocytes was observed in the metatarsals cultured in 7 mM phosphate. Immunohistochemical analyses of embryonic bones demonstrated activation of caspase-9 in hypertrophic chondrocytes, associated with vascular invasion. Thus, these investigations demonstrate that phosphate promotes chondrocyte differentiation during embryonic development and implicate a physiological role for phosphate activation of the mitochondrial apoptotic pathway during embryonic endochondral bone formation. Keywords phosphate; embryonic; bone; development Phosphate is critical for a vast array of cellular processes and, together with calcium, is one of the major components of the skeleton. Extracellular phosphate regulates apoptosis of terminally differentiated hypertrophic chondrocytes during postnatal growth plate maturation. Impaired apoptosis of the late hypertrophic chondrocyte layer is a feature of rachitic hypophosphatemic disorders such as hereditary vitamin D-resistant rickets and X-linked hypophosphatemia [Makras et al., 2008;Sabbagh et al., 2005]. Studies in Hyp mice, a mouse model of X-linked hypophosphatemia, demonstrate that development of hypophosphatemia is associated with a decrease in apoptosis of hypertrophic chondrocytes and expansion of the growth plate, revealing a correlation among serum phosphate levels, programmed cell death of hypertrophic chondrocytes, and the development of rickets [Sabbagh et al., 2005]. The hypothesis that phosphate is a key regulator of hypertrophic chondrocyte apoptosis is supported by investigations in the calcium-sensing receptor knockout mice. Due to impaired parathyroid calcium sensing, these mice exhibit hyperparathyroidism that leads to hypophosphatemia and,