P l a c e b o D o s e d - arcusbio.com · with flow cytometry: Sijranke Post, Richard Draaijer, Tom...
Transcript of P l a c e b o D o s e d - arcusbio.com · with flow cytometry: Sijranke Post, Richard Draaijer, Tom...
RESEARCH POSTER PRESENTATION DESIGN © 2015
www.PosterPresentations.com
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Schedule of PD Assessments
Adenosine Receptor Mediated pCREB Signaling
Relationship Between Mean AB928 Plasma Levels and PD Endpoints
AB928 PK Profile Supports Once Daily Dosing at Steady State
AB928 (150 mg qd) Provides Maximal Inhibition of A2aR-Mediated pCREB Increases
on CD8+ T cells at Steady State
PK/PD Correlation in AB928 Dosed Subjects Measured by pCREB Inhibition of 5 mM NECA
Effects on CD8+ T cells
INTRODUCTION
METHODS
RESULTS
• AB928 has demonstrated an excellent oral PK profile in
human subjects, consistent with once-daily dosing.
• Dose levels of AB928 have been identified that provide
maximal adenosine receptor coverage in the blood. At
these dose levels, AB928 has been shown to be safe and
well-tolerated and no effects have been noted on
physiological parameters generally associated with
adenosine inhibition.
• Assessing pCREB levels on whole blood CD8+ T cells
following ex vivo stimulation with 5 µM NECA provides an
excellent measure of the PD effects of AB928 in dosed
subjects. Consistent with previously generated in vitro
data, AB928 plasma levels ≥ 1 µM are associated with ≥
90% adenosine receptor inhibition.
• The clear PK/PD correlation obtained for AB928 in the
ongoing Phase 1 study in healthy volunteers will be used
to guide dose selection for future combination studies in
oncology, several of which are expected to be initiated
later this year.
We also wish to thank PRA Health Sciences in the Netherlands for assistancewith flow cytometry: Sijranke Post, Richard Draaijer, Tom Huizinga, PatrickVeerman , Frank Beltman, Riejanne Bax-Seigers and Janet Stegehuis.
CONCLUSIONS
Seitz L, Ashok D, Leleti M, Powers J, Rosen B, Miles D, Sharif E, Jin L, Park A, Young S, Soriano F, Rieger A, Karakunnel J, Walters MJ
Arcus Biosciences, Inc. 3928 Point Eden Way, Hayward, CA 94545, USA
Clinical Pharmacokinetic-Pharmacodynamic Relationship for AB928, a Dual Antagonist of the A2aR and A2bR Adenosine Receptors
In many tumors, extracellular adenosine contributes to an
immunosuppressed tumor micro-environment (TME) via
activation of the A2a receptor (A2aR), expressed on lymphocytes,
and the A2b receptor (A2bR), expressed on myeloid cells. Relative
to other tissues like the brain, adenosine concentrations in the
TME are much higher. Also unlike the brain, tumors contain high
levels of albumin, to which many small molecule drugs bind non-
specifically. AB928 is a novel and selective dual A2aR/A2bR
antagonist designed to potently block the immunosuppressive
effects of adenosine in the TME.
An ongoing placebo-controlled (3:1) study of AB928 is being
conducted in healthy volunteers to study the safety, tolerability,
pharmacokinetics (PK) and pharmacodynamics (PD) of the drug.
This poster describes the preliminary PK and PD (receptor
coverage in blood T cells) data from the healthy volunteer study.
This information is being used to help guide dose selection in
several combination studies in oncology that will be initiated
later this year.
Phase 1 Healthy Volunteer Study: This Phase 1 healthy
volunteer study has single ascending dose (SAD) and multiple
ascending dose (MAD) arms. In the SAD arm, we are
evaluating single doses of 10, 25, 75, and 150 mg, and two
doses of 100 mg, 12 hours apart. In the MAD arm, we are
evaluating single daily doses of 10, 25, 75, 150 and 200 mg
administered for 4 consecutive days. As of the data cut-off
date (DCO) of 3/30/18, all doses up to 150 mg in the SAD and
MAD arms have been completed. The study is ongoing and
remains blinded; no trends have been observed on
physiological parameters potentially sensitive to adenosine
inhibition and there have been no safety events preventing
escalation to higher cohorts.
NECA-Induced pCREB Increases in Peripheral Immune Cells Are Blocked by AB928
Bioanalytical / PK analysis: Plasma samples were prepared bya protein precipitation extract procedure. The analyte, AB928,and internal standard, D6-AB928, were extracted from plasmawith acetonitrile/methanol (90/10, v/v). Concentrations ofAB928 in the extracts were determined by LC-MS/MS.Descriptive pharmacokinetic parameters were obtained by astandard non-compartmental analysis from the plasmaconcentration-time curves using Phoenix WinNonlin v6.3 orhigher (Certara, Princeton, NJ).
Multi-color Phospho-flow Cytometry: Monoclonal antibodiesto cell type specific markers including fluorochrome labelledanti-pCREB (Cyclic AMP Response Element Binding Protein)antibody were used to identify inhibition of CREBphosphorylation in placebo and dosed subjects.
Clinical Study Design
Predose No NECA
Predose No NECA
Predose + NECA
Predose + NECA
+ AB928 + NECA
+ AB928 + NECA
NECA induced a significant increase in pCREB (grey vs. redhistograms) in peripheral blood immune cells. This increase, inresponse to 5 mM NECA, is still inhibited at trough plasma levelsfollowing 4 once daily doses with 150 mg AB928 (bluehistograms). Prior to dosing, NECA-induced pCREB elevationswere observed in CD8+ T cells in all subjects evaluated to date.The ability to capture the effects of NECA on CD14+ cells wasimpeded by the smaller assay window; however, when thepCREB signal was observed on monocytes, AB928 was able toinhibit it as shown here.
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Rationale for NECA Concentration Selection: Previous
experiments conducted in vitro indicate that NECA is at least
20 times more potent than adenosine at inducing CREB
phosphorylation in human blood; thus, our PD analysis is
focused on the 5 µM NECA stimulation under physiologically
relevant conditions. 5 mM NECA provided maximal induction
of pCREB. We believe this provides receptor inhibition data
comparable to what we might expect from ≥ 100 µM intra-
tumoral adenosine. AB928 displays ~100% penetration of
mouse tumors (plasma: tumor AUC ratio ~1) (see Walters et al,
Abstract No. 3518 at this meeting).
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pCREB in Human Whole Blood: The inhibition of A2aR-mediated
effects by AB928 was determined in blood samples from the
Phase 1 study by the decreased phosphorylation of CREB
following stimulation ex vivo with the adenosine receptor agonist
NECA (5'-N-ethylcarboxamidoadenosine). At each PD time point,
levels of pCREB were assessed by flow cytometry both in the
absence and following ex vivo stimulation with 1, 5 and 10 µM
NECA. In order to capture the antagonism of AB928 on both the
A2aR and A2bR receptors, we assessed levels of pCREB on blood
CD8+ T cells and CD14+ monocytes.