A Biomarker Signature to Predict Complete Response to Itacitinib and Corticosteroids in Acute Graft Versus Host Disease

BACKGROUND: Acute graft versus host disease (aGVHD) represents a serious and potentially life-threatening condition in patients receiving hematopoietic stem cell transplantation (HSCT). Development of aGVHD is characterized by increased levels of inflammatory mediators and activated T cells in circulation, leading to tissue and organ damage. Previously, we demonstrated that a panel measuring ST2, REG3A, and TNFR1 poorly predicted response to the combination of corticosteroids and itacitinib, a potent and highly selective JAK1 inhibitor, in a parallel-cohort phase 1 trial (NCT02614612). In this study, we utilized broad proteomic analysis to identify potentially predictive biomarkers of therapeutic response to the combination treatment. METHODS: Plasma samples were collected from 25 patients enrolled in the Phase 1 clinical trial prior to and at designated times following treatment. Broad proteomic analysis was conducted by OLINK Proteomics using a proximity extension assay. Selected biomarkers were quantitated by the same method based on standard curves generated using recombinant proteins. Statistical differences were identified using unpaired T tests and significance conferred when p&lt;0.05. All participants provided written consent before enrollment. RESULTS: The 25 patients in this study were stratified based on overall response to treatment with itacitinib and corticosteroid at day 28 (based on CIBMTR). Patients included 10 complete responders (CR), 1 very good partial responder (VGPR), 8 partial responders (PR) and 6 patients with progressive disease and/or death (PD/death) prior to day 28. Novel biomarkers were identified and associated with therapeutic response by comparing the levels of approximately 1000 proteins in the CR (N=10) and PD/Death (N=6) cohorts specifically. The initial analysis identified 50 proteins significantly upregulated (P&lt;.05) and 52 proteins significantly down-regulated (P&lt;.05) in the CR cohort at baseline compared with the PD/Death cohort. The list of candidates were further screened based on correlation to known aGVHD biomarkers, degree of separation between the populations, as well as reliable and consistent testing (ie, coefficient of variation &lt;20%). From these analyses, candidate biomarkers were identified and representative examples are shown in table 1. Novel biomarkers include macrophage chemotactic protein 3 (MCP3/CCL7), stem cell factor (SCF/KIT-L), interleukin 8 (IL8), and tumor necrosis factor receptor super family 6B (TNFRSF6B). Each of these candidate biomarkers demonstrated a significant (P&lt;.05) difference between CR and PD/death cohorts, with intermediate levels detected in patients with an intermediate (VGPR/PR) response to treatment. Because MCP3, IL8, and TNFRSF6B presumably associate with inflammation, elevation of these biomarkers in the PD/Death cohort that poorly respond to a JAK inhibitor (JAKi) is not surprising. In addition, elevation of SCF in responders to JAKi is consistent with supporting hematopoiesis. CONCLUSION: Potentially novel biomarkers may be useful in predicting complete responses to treatment with a combination of corticosteroids and itacitinib in patients with aGVHD post HSCT. Disclosures Pratta: Incyte Research Institute: Employment. Liu:Incyte: Employment, Equity Ownership. Owens:Incyte Corporation: Employment, Equity Ownership. Yan:Incyte Corporation: Employment. Arbushites:Incyte: Employment. Howell:Incyte: Employment. </jats:sec

Plasma Biomarker Association with Response in Acute GVHD Subjects Treated with the Combination of Itacitinib and Corticosteroids in a Phase 1 Clinical Trial

Abstract BACKGROUND: Acute Graft versus Host Disease (aGVHD) represents a serious and sometimes life-threatening condition associated with patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT). Development of aGVHD is characterized by increased levels of inflammatory mediators and activated T cells in circulation, leading to tissue and organ damage. Corticosteroids are primarily utilized as first line treatment for aGVHD; however, this approach does not provide therapeutic benefit for a significant portion of aGVHD subjects. The combination of itacitinib, a JAK1-selective inhibitor, with corticosteroids was evaluated in a parallel-cohort phase 1 trial (NCT02614612) and resulted in improved overall responses for both steroid naïve and refractory aGVHD subjects. Previous studies have demonstrated that a panel measuring the plasma levels of ST2, REG3A, and TNFR1 can be utilized to distinguish steroid treated subjects with an increased risk of progressive aGVHD; however, it is unknown if these biomarkers are predictive of response to the combination of corticosteroids and itacitinib. In this study, we compared the plasma levels of ST2, REG3A, TNFR1, and Trappin-2/Elafin in order to distinguish response to combination treatment. Additionally, we conducted a broad proteomic analysis to identify potential prognostic biomarkers of response to the combination treatment. METHODS: Plasma samples were collected from 31 subjects enrolled in the Phase 1 clinical trial prior to and at designated times following treatment. Levels of REG3A, ST2, TNFR1, and Trappin-2/Elafin were measured using SimplePlex multiplex platform based on manufacturer instructions. Broad proteomic analysis was additionally conducted by OLINK Proteomics using a proximity extension assay. Statistical differences were identified using unpaired T tests and significance conferred when p&lt;0.05. All subjects provided written consent prior to enrollment. RESULTS: Subjects were separated into responders (10- Complete Responder, 1-Very Good Partial Responder, 8-Partial Responder) and non-responders (2-Mixed Responder, 10-Progressive Disease/Death) based on CIBMTR response criteria at day 28. Levels of ST2 and TNFR1 were significantly elevated at baseline in non-responders (p&lt;0.05 for both ST2 and TNFR1) when compared with responders (Table 1). Additionally, baseline levels of ST2 and TNFR1 significantly correlated (p&lt;0.0001 for both ST2 and TNFR1) with the Minnesota and CIBMTR response criteria for aGVHD. There were no significant differences in the levels of REG3A and Trappin-2/Elafin between responders and non-responders. Novel biomarkers were identified and associated with therapeutic response by comparing the levels of approximately 1000 proteins in the CR and PD/Death cohorts specifically. The initial analysis identified 44 proteins significantly upregulated (p&lt;0.05; fold change &gt; 1.5) and 61 proteins significantly down-regulated (p&lt;0.05; fold change &lt; -1.5) in the CR cohort at baseline compared with the PD/Death cohort. Further analysis of the CR cohort identified 23 proteins significantly modulated (Fold Change &gt; |1.5|, p&lt;0.05) between baseline and day 28 samples which may serve as additional biomarkers of therapeutic response. CONCLUSION: Proteomic analysis of clinical samples confirmed the value of ST2 and TNFR1 in predicting response to treatment with itacitinib and steroids and also identified a number of novel plasma biomarkers that may have utility in selecting and/or monitoring aGVHD subjects when treated with a combination of corticosteroids and itacitinib. Disclosures Pratta: Incyte Research Institute: Employment, Equity Ownership. Liu:Incyte Research Institute: Employment, Equity Ownership. Arbushites:Incyte Corporation: Employment, Equity Ownership. Newton:Incyte Research Institute: Employment, Equity Ownership. Howell:Incyte Research Institute: Employment, Equity Ownership. </jats:sec

Stratification of Responders and Non-Responders in the Reach-1 Trial Based on Serum Proteomic Analysis

Acute graft versus host disease (aGVHD) is a serious and potentially life-threatening condition that can develop in patients receiving hematopoietic stem cell transplantation (HSCT). Acute GVHD is characterized by increased levels of inflammatory mediators and signaling through the Janus Kinases (JAKs), leading to tissue and organ damage. Ruxolitinib, an oral JAK1/JAK2 inhibitor, is the first FDA-approved treatment for steroid refractory aGVHD. The current study evaluated proteomic signatures from participants in the REACH-1 clinical trial to identify those individuals which have an increased probability for success when treated with ruxolitinib in combination with corticosteroids. Plasma was collected for 42 participants enrolled in the REACH-1 clinical trial (NCT02953678) prior to and at designated times following treatment. Broad proteomic analysis of more than 1000 proteins was conducted using the OLINK proximity extension assay. Participants were separated into responders (complete responders, very good partial responders, partial responders) (n=36) or non-responders (mixed responders, progressive disease) (n=6) based on their clinical response at Day 28 of treatment. Baseline differences in day 28 responders versus non-responders were compared using t-tests. Pharmacodynamics changes within responders and non-responders were assessed using paired t-tests. Significance of statistical tests was conferred at p&lt;0.05. Broad proteomic analysis of plasma identified a total of 145 differentially expressed proteins (p&lt;0.05) between the responders and non-responders at baseline. Thirty-five proteins were elevated and 110 proteins were lower in responders compared to non-responders. At baseline, IL-8, IL-6, and IL-24 were among the most significantly down-regulated while SCF was one of the most significantly up-regulated in responders compared to non-responders. Pharmacodynamic analyses revealed 493 significantly modulated proteins in responders and 92 in non-responders. IL2-RA was among the most significantly down-regulated from baseline to day 28 in both responders and non-responders. This study suggests that proteomic characterization has the potential to stratify responders and non-responders to ruxolitinib and corticosteroid treatment in steroid refractory aGVHD. Additionally, this study demonstrated robust pharmacodynamic and correlative changes in responders following treatment with ruxolitinib and corticosteroids suggesting that defining a responder population could enrich for patients predisposed to positive therapeutic response; however, this should be prospectively validated in additional studies. Disclosures Owens: Incyte Corporation: Employment, Equity Ownership. Pratta:Incyte Research Institute: Employment. Liu:Incyte: Employment, Equity Ownership. Arbushites:Incyte: Employment. Tian:Incyte: Employment, Equity Ownership. Howell:Incyte: Employment. </jats:sec