Phase I study of CC-90010, a reversible, oral BET inhibitor in patients with advanced solid tumors and relapsed/refractory non-Hodgkin's lymphoma

BACKGROUND

Bromodomain and extra-terminal (BET) proteins are epigenetic readers that regulate expression of genes involved in oncogenesis. CC-90010 is a novel, oral, reversible, small-molecule BET inhibitor.

PATIENTS AND METHODS

CC-90010-ST-001 (NCT03220347; 2015-004371-79) is a phase I dose-escalation and expansion study of CC-90010 in patients with advanced or unresectable solid tumors and relapsed/refractory (R/R) non-Hodgkin's lymphoma (NHL). We report results from the dose escalation phase, which explored 11 dose levels and four dosing schedules, two weekly (2 days on/5 days off; 3 days on/4 days off), one biweekly (3 days on/11 days off), and one monthly (4 days on/24 days off). The primary objectives were to determine the safety, maximum tolerated dose (MTD) and/or recommended phase II dose (RP2D) and schedule. Secondary objectives were to evaluate signals of early antitumor activity, pharmacokinetics, and pharmacodynamics.

RESULTS

This study enrolled 69 patients, 67 with solid tumors and two with diffuse large B-cell lymphoma (DLBCL). The median age was 57 years (range, 21-80) and the median number of prior regimens was four (range, 1-9). Treatment-related adverse events (TRAEs) were mostly mild and manageable; grade 3/4 TRAEs reported in more than two patients were thrombocytopenia (13%), anemia, and fatigue (4% each). Six patients had dose-limiting toxicities. MTDs were 15 mg (2 days on/5 days off), 30 mg (3 days on/11 days off), and 45 mg (4 days on/24 days off). The RP2D and schedule selected for expansion was 45 mg (4 days on/24 days off). As of 8 October 2019, one patient with grade 2 astrocytoma achieved a complete response, one patient with endometrial carcinoma had a partial response, and six patients had prolonged stable disease ≥11 months.

CONCLUSIONS

CC-90010 is well tolerated, with single-agent activity in patients with heavily pretreated, advanced solid tumors.

Role of corticotropin-releasing factor receptor-1 in opiate withdrawal

Previous studies indicate that corticotropin-releasing factor (CRF) contributes to the anxiety-like and aversive states associated with drug-induced withdrawal. The present study extends this work by analyzing the CRF receptor subtype involved in withdrawal responses. First, the influence of a selective CRF receptor-1 (CRF-R1) antagonist, CP-154,526, on opiate withdrawal behavior was examined. Pretreatment with the CRF-R1 antagonist significantly attenuated several behavioral signs of naltrexone-induced morphine withdrawal, including writhing, chewing, weight loss, lacrimation, salivation, and irritability, measured during the first hour of withdrawal. Next the expression of CRF-R1 was determined as a second measure of the involvement of this receptor in opiate withdrawal. Naltrexone-induced morphine withdrawal resulted in down-regulation of CRF-R1 mRNA in several brain regions, including the frontal cortex, parietal cortex, striatum, nucleus accumbens, and amygdala, but not in the hypothalamus or periaqueductal gray. Expression of CRF-R2, the other major CRF receptor subtype, was not down-regulated significantly by withdrawal in any of the regions examined, although morphine alone significantly increased levels of this receptor subtype. Taken together, the behavioral and receptor regulation findings indicate that CRF-R1 is the primary mediator of the actions of the CRF system on opiate withdrawal, although it is possible that CRF-R2 contributes to the response.

Protein kinase C-mediated down-regulation of beta1-adrenergic receptor gene expression in rat C6 glioma cells

In the current study, we investigated the mechanism by which protein kinase C (PKC) regulates the expression of beta1-adrenergic receptor (beta1AR) mRNA in rat C6 glioma cells. Exposure of the cells to 4beta-phorbol-12-myristate-13-acetate (PMA), an activator PKC, resulted in a down-regulation of both beta1AR binding sites and mRNA levels in a time- and concentration-dependent manner. This effect was not observed with phorbol esters that do not activate PKC and was blocked by bisindolylmaleimide, a specific PKC inhibitor. Activation of PKC did not reduce the half-life of beta1AR mRNA but significantly decreased the activity of the beta1AR promoter, as determined by reporter analysis. A putative response element, with partial homology to a consensus cAMP response element, was identified by mutation analysis of the promoter at positions -343 to -336, relative to the translational start site. Mutation of this putative regulatory element, referred to as a beta1AR-PKC response element, completely blocked the PKC-mediated down-regulation of beta1AR promoter activity. Gel mobility shift analysis detected two specific bands when C6 cell extracts were incubated with a labeled DNA probe containing the beta1AR-PKC response element sequence. Formation of one of these bands was inhibited by an oligonucleotide probe containing a consensus CRE and disrupted by an antibody for cAMP response element binding protein. Based on these studies, we propose that the PKC-induced down-regulation of beta1AR gene transcription in C6 cells is mediated in part by a cAMP response element binding protein-dependent mechanism acting on a novel response element.

Antipyretic role of endogenous melanocortins mediated by central melanocortin receptors during endotoxin-induced fever

Bacterial infection causes fever, an adaptive but potentially self-destructive response, in the host. Also activated are counterregulatory systems such as the pituitary-adrenal axis. Antipyretic roles have also been postulated for certain endogenous central neuropeptides, including the melanocortins (alpha-MSH-related peptides). To test the hypothesis that endogenous central melanocortins have antipyretic effects mediated by central melanocortin receptors (MCRs), we determined the effect of intracerebroventricular injection of a synthetic MCR antagonist, Ac-Nle4,c-[Asp5,DNal(2')7,Lys10]alpha-MSH(4-10)-NH2 (SHU-9119) in endotoxin-challenged rats. The efficacy and specificity of SHU-9119 as an MCR antagonist in the rat was first validated in vitro and in vivo. In vitro, in heterologous cells expressing either rat MC3-R or MC4-R, the major MCR subtypes expressed in brain, SHU-9119 showed no intrinsic agonism, but it inhibited alpha-MSH-induced cAMP accumulation (IC50 = 0.48 +/- 0.19 and 0.41 +/- 0.28 nM, respectively) and [125I]-[Nle4,DPhe7]-alpha-MSH binding (IC50 = 1.0 +/- 0.1 and 0.9 +/- 0.3 nM, respectively). In vivo, exogenous alpha-MSH (180 pmol) inhibited fever in rats when administered intracerebroventricularly 30 min after Escherichia coli lipopolysaccharide (LPS) (25 microg/kg, i.p.). When co-injected with alpha-MSH, SHU-9119 (168 pmol, i.c.v.) prevented the antipyretic action of exogenous alpha-MSH. In contrast, neither alpha-MSH nor SHU-9119, alone or in combination, affected body temperatures in afebrile rats. In LPS-treated rats, intracerebroventricular injection of SHU-9119 significantly increased fever, whereas intravenous injection of the same dose of SHU-9119 had no effect. Neither intracerebroventricular nor intravenous SHU-9119 significantly affected LPS-stimulated plasma ACTH or corticosterone levels. The results indicate that endogenous central melanocortins exert an antipyretic influence during fever by acting on MCRs located within the brain, independent of any modulation of the activity of the pituitary-adrenal axis.

Melanocortins and opiate addiction

Adrenocorticotropic hormone (ACTH) and alpha-melanocyte stimulating hormone (alpha-MSH) are centrally acting melanocortin peptides with numerous reported functions, including induction of excessive grooming and antipyresis, among others. Also reported is a role for melanocortins in aspects of opiate action. Although early work examined the effects of ACTH and MSH on opiate-induced behaviors, further progress has been limited. Recently, however, advances in the identification and characterization of melanocortin receptor (MC-R) subtypes have provided novel tools with which to study interactions between melanocortins and addiction. The present review discusses the effects of ACTH and MSH on opiate-induced behaviors and relates these findings to more recent reports on the regulation of melanocortin systems by exogenous opiates. Emerging from these data is the possibility that melanocortin receptor activation, specifically at the MC4-R subtype, may act to antagonize certain properties of exogenous opiates, including perhaps addiction.

Morphine down-regulates melanocortin-4 receptor expression in brain regions that mediate opiate addiction

Melanocortin peptides are reported to antagonize opiate dependence and tolerance, but the neural substrates underlying these actions are unknown. In this study, we characterize the rat melanocortin-4 receptor (MC4-R) and demonstrate that this receptor is regulated by opiate administration. The rat MC4-R is 95% identical to the human MC4-R, and the potency of melanocortin peptides to stimulate cAMP production is similar in these two species homologs (alpha-melanocyte-stimulating hormone = adrenocorticotropic hormone > gamma-melanocyte-stimulating hormone). Expression of MC4-R mRNA was found to be enriched in the striatum, nucleus accumbens, and periaque-ductal gray, all of which are regions implicated in the behavioral effects of opiates. In contrast, MC1-, MC3-, and MC5-R are expressed at very low or undetectable levels in these brain regions. Chronic administration of morphine (5 days) resulted in a time-dependent down-regulation of MC4-R mRNA expression in the striatum and periaqueductal gray. Expression of MC4-R mRNA was also decreased in the nucleus accumbens/ olfactory tubercle, but this effect was observed after 1 or 3 days of morphine treatment. In the striatum, the reduction of MC4-R mRNA was accompanied by a concomitant decrease in melanocortin receptor levels, shown by quantitative radioligand binding and autoradiography. In contrast, morphine administration did not influence levels of MC4-R mRNA in several other brain regions, including frontal cortex, olfactory bulb, hypothalamus, and ventral tegmentum/substantia nigra. In light of previous findings that melanocortins antagonize opiate self-administration, analgesic tolerance, and physical dependence, we hypothesize that decreased melanocortin function, via down-regulation of MC4-R expression, may contribute to the development of these opiate-induced behaviors.