Tumors establish resistance to immunotherapy by regulating Treg recruitment via CCR4.

BACKGROUND: Checkpoint inhibitors (CPIs) such as anti-PD(L)-1 and anti-CTLA-4 antibodies have resulted in unprecedented rates of antitumor responses and extension of survival of patients with a variety of cancers. But some patients fail to respond or initially respond but later relapse as they develop resistance to immune therapy. One of the tumor-extrinsic mechanisms for resistance to immune therapy is the accumulation of regulatory T cells (Treg) in tumors. In preclinical and clinical studies, it has been suggested that tumor trafficking of Treg is mediated by CC chemokine receptor 4 (CCR4). Over 90% of human Treg express CCR4 and migrate toward CCL17 and CCL22, two major CCR4 ligands that are either high at baseline or upregulated in tumors on CPI treatment. Hence, CCR4 antagonism has the potential to be an effective antitumor treatment by reducing the accumulation of Treg into the tumor microenvironment (TME). METHODS: We developed in vitro and in vivo models to assess Treg migration and antitumor efficacy using a potent and selective CCR4 antagonist, CCR4-351. We used two separate tumor models, Pan02 and CT26 mouse tumors, that have high and low CCR4 ligand expression, respectively. Tumor growth inhibition as well as the frequency of tumor-infiltrating Treg and effector T cells was assessed following the treatment with CCR4 antagonist alone or in combination with CPI. RESULTS: Using a selective and highly potent, novel small molecule inhibitor of CCR4, we demonstrate that migration of CCR4+ Treg into the tumor drives tumor progression and resistance to CPI treatment. In tumor models with high baseline levels of CCR4 ligands, blockade of CCR4 reduced the number of Treg and enhanced antitumor immune activity. Notably, in tumor models with low baseline level of CCR4 ligands, treatment with immune CPIs resulted in significant increases of CCR4 ligands and Treg numbers. Inhibition of CCR4 reduced Treg frequency and potentiated the antitumor effects of CPIs. CONCLUSION: Taken together, we demonstrate that CCR4-dependent Treg recruitment into the tumor is an important tumor-extrinsic mechanism for immune resistance. Blockade of CCR4 led to reduced frequency of Treg and resulted in increased antitumor activity, supporting the clinical development of CCR4 inhibitors in combination with CPI for the treatment of cancer. STATEMENT OF SIGNIFICANCE: CPI upregulates CCL17 and CCL22 expression in tumors and increases Treg migration into the TME. Pharmacological antagonism of the CCR4 receptor effectively inhibits Treg recruitment and results in enhanced antitumor efficacy either as single agent in CCR4 ligandhigh tumors or in combination with CPIs in CCR4 ligandlow tumors.

Novel Piperidinyl-Azetidines as Potent and Selective CCR4 Antagonists Elicit Antitumor Response as a Single Agent and in Combination with Checkpoint Inhibitors.

The C-C chemokine receptor 4 (CCR4) is broadly expressed on regulatory T cells (Treg) as well as other circulating and tissue-resident T cells. Treg can be recruited to the tumor microenvironment (TME) through the C-C chemokines CCL17 and CCL22. Treg accumulation in the TME has been shown to dampen the antitumor immune response and is thought to be an important driver in tumor immune evasion. Preclinical and clinical data suggest that reducing the Treg population in the TME can potentiate the antitumor immune response of checkpoint inhibitors. We have developed small-molecule antagonists of CCR4, featuring a novel piperidinyl-azetidine motif, that inhibit the recruitment of Treg into the TME and elicit antitumor responses as a single agent or in combination with an immune checkpoint blockade. The discovery of these potent, selective, and orally bioavailable CCR4 antagonists, and their activity in in vitro and in vivo models, is described herein.

Discovery of a Potent and Selective CCR4 Antagonist That Inhibits Treg Trafficking into the Tumor Microenvironment.

Recruitment of suppressive CD4+ FOXP3+ regulatory T cells (Treg) to the tumor microenvironment (TME) has the potential to weaken the antitumor response in patients receiving treatment with immuno-oncology (IO) agents. Human Treg express CCR4 and can be recruited to the TME through the CC chemokine ligands CCL17 and CCL22. In some cancers, Treg accumulation correlates with poor patient prognosis. Preclinical data suggests that preventing the recruitment of Treg and increasing the population of activated effector T cells (Teff) in the TME can potentiate antitumor immune responses. We developed a novel series of potent, orally bioavailable small molecule antagonists of CCR4. From this series, several compounds exhibited high potency in distinct functional assays in addition to good in vitro and in vivo ADME properties. The design, synthesis, and SAR of this series and confirmation of its in vivo activity are reported.

Alcohol-related harm in emergency departments: a prospective, multi-centre study.

BACKGROUND AND AIMS: Emergency department (ED) alcohol-related presentation data are not routinely collected in Australia and New Zealand. It is likely that previous research has underestimated the numbers of patients presenting with alcohol-related conditions. This study aimed to quantify the level of alcohol harm presenting to EDs in Australia and New Zealand [Correction added on 23 Jan 2018, after first online publication: The 'aims' section was missing and is updated in this version]. DESIGN: Multi-centre, prospective study. Patients were screened prospectively for alcohol-related presentations during a 7-day period in December 2014. Part 1 involved screening to determine alcohol-positive ED presentations and data collection of patient demographic and clinical information. Part 2 involved a consent-based survey conducted with patients aged ≥ 14 years to perform Alcohol Use Disorders Identification Test (AUDIT) scores. SETTING: Eight EDs in Australia and New Zealand, representing differing hospital role delineations. PARTICIPANTS: A total of 8652 patients aged ≥ 14 years attended and 8435 (97.5%) were screened. MEASUREMENTS: The main outcome measure was the proportion of patients who had an alcohol-related presentation termed 'alcohol-positive', using pre-defined criteria. It included injuries, intoxication, medical conditions and injuries caused by an alcohol-affected third party. Secondary outcomes included demographic and clinical information, the type of alcohol-related presentations and AUDIT scores. FINDINGS: A total of 801 [9.5%; 95% confidence interval (CI) = 8.9-10.1%] presentations were identified as alcohol-positive, ranging between 4.9 and 15.2% throughout sites. Compared with alcohol-negative patients, alcohol-positive patients were more likely to be male [odds ratio (OR) = 1.90, 95% CI = 1.63-2.21], younger (median age 37 versus 46 years, P < 0.0001), arrive by ambulance (OR = 1.94, 95% CI = 1.68-2.25) or police/correctional vehicle (OR = 4.56, 95% CI = 3.05-6.81) and require immediate treatment (OR = 3.20, 95% CI = 2.03-05.06). The median AUDIT score was 16 (interquartile range = 10-24). CONCLUSIONS: Almost one in 10 presentations to emergency departments in Australia and New Zealand are alcohol related.

Perceptions of Australasian emergency department staff of the impact of alcohol-related presentations.

OBJECTIVES: To survey emergency department (ED) clinical staff about their perceptions of alcohol-related presentations. DESIGN, SETTING AND PARTICIPANTS: A mixed methods online survey of ED clinicians in Australia and New Zealand, conducted from 30 May to 7 July 2014. MAIN OUTCOME MEASURES: The frequency of aggression from alcohol-affected patients or their carers experienced by ED staff; the perceived impact of alcohol-related presentations on ED function, waiting times, other patients and staff. RESULTS: In total, 2002 ED clinical staff completed the survey, including 904 ED nurses (45.2%) and 1016 ED doctors (50.7%). Alcohol-related verbal aggression from patients had been experienced in the past 12 months by 97.9% of respondents, and physical aggression by 92.2%. ED nurses were the group most likely to have felt unsafe because of the behaviour of these patients (92% reported such feelings). Alcohol-related presentations were perceived to negatively or very negatively affect waiting times (noted by 85.5% of respondents), other patients in the waiting room (94.4%), and the care of other patients (88.3%). Alcohol-affected patients were perceived to have a negative or very negative impact on staff workload (94.2%), wellbeing (74.1%) and job satisfaction (80.9%). CONCLUSIONS: Verbal and physical aggression by alcohol-affected patients is commonly experienced by ED clinical staff. This has a negative impact on the care of other patients, as well as on staff wellbeing. Managers of health services must ensure a safe environment for staff and patients. More importantly, a comprehensive public health approach to changing the prevailing culture that tolerates alcohol-induced unacceptable behaviour is required.

Survey of alcohol-related presentations to Australasian emergency departments.

OBJECTIVE: To determine the proportion of alcohol-related presentations to emergency departments (EDs) in Australia and New Zealand, at a single time point on a weekend night shift. DESIGN, SETTING AND PARTICIPANTS: A point prevalence survey of ED patients either waiting to be seen or currently being seen conducted at 02:00 local time on 14 December 2013 in 106 EDs in Australia and New Zealand. MAIN OUTCOME MEASURES: The number of ED presentations that were alcohol-related, defined using World Health Organization ICD-10 codes. RESULTS: At the 106 hospitals (92 Australia, 14 New Zealand) that provided data, 395 (14.3%; 95% CI, 13.0%-15.6%) of 2766 patients in EDs at the study time were presenting for alcohol-related reasons; 13.8% (95% CI, 12.5%-15.2%) in Australia and 17.9% (95% CI, 13.9%-22.8%) in New Zealand. The distribution was skewed left, with proportions ranging from 0 to 50% and a median of 12.5%. Nine Australian hospitals and one New Zealand hospital reported that more than a third of their ED patients had alcohol-related presentations; the Northern Territory (38.1%) and Western Australia (21.1%) reported the highest proportions of alcohol-related presentations. CONCLUSIONS: One in seven ED presentations in Australian and New Zealand at this 02:00 snapshot were alcohol-related, with some EDs seeing more than one in three alcohol-related presentations. This confirms that alcohol-related presentations to EDs are currently underreported and makes a strong case for public health initiatives.