Exposure-Response Analyses of Tremelimumab Monotherapy or in Combination with Durvalumab in Patients with Unresectable Hepatocellular Carcinoma

PURPOSE

A novel single-dose regimen of 300 mg tremelimumab in combination with durvalumab [Single Tremelimumab Regular Interval Durvalumab (STRIDE)] has demonstrated a favorable benefit-risk profile in the phase I/II Study 22 (NCT02519348) and phase III HIMALAYA study (NCT03298451). This study evaluated the pharmacokinetics, exposure-response, and exposure-pharmacodynamics relationships of tremelimumab in patients with unresectable hepatocellular carcinoma (uHCC).

PATIENTS AND METHODS

A previous tremelimumab population pharmacokinetic model was validated using data from parts 2 and 3 of Study 22. Exposure-response analyses explored relationships of tremelimumab exposure with efficacy and safety. Pharmacokinetics and pharmacodynamics relationships were evaluated using linear and nonlinear regression models.

RESULTS

The observed pharmacokinetics of tremelimumab in uHCC were consistent with predictions; no significant covariates were identified. Tremelimumab exposure was not significantly associated with adverse events, objective response rate, or progression-free survival. Overall survival (OS) was longer for patients with tremelimumab exposure, minimum serum drug concentration (Cmin1) ≥ median versus Cmin1 < median (18.99 months vs. 10.97 months), but this exposure-survival analysis might be confounded with baseline characteristics of albumin level and neutrophil to lymphocyte ratio, which had a significant impact on OS (P = 0.0004 and 0.0001, respectively). The predicted Cmin1 of tremelimumab in STRIDE regimen (12.9 μg/mL) was greater than the estimated concentration of tremelimumab eliciting half-maximal increases (EC50 = 5.24 μg/mL) in CD8+Ki67+ T-cell counts.

CONCLUSIONS

Our findings support novel insights into tremelimumab pharmacokinetics and exposure-response relationships in HCC and support the clinical utility of the STRIDE regimen in patients with uHCC.

Gemcitabine and cisplatin plus durvalumab with or without tremelimumab in chemotherapy-naive patients with advanced biliary tract cancer: an open-label, single-centre, phase 2 study

BACKGROUND

Immunotherapies have shown clinical activity in patients with advanced biliary tract cancer, for which outcomes remain poor despite standard of care treatment with gemcitabine and cisplatin. We aimed to evaluate gemcitabine and cisplatin plus durvalumab with or without tremelimumab as first-line treatment in patients with advanced biliary tract cancer.

METHODS

This open-label, single-centre, phase 2 study was conducted at Seoul National University Hospital. Eligible patients were treatment-naïve adults aged 18 years or older with histologically proven unresectable or recurrent biliary tract cancer, at least one measurable lesion based on the Response Evaluation Criteria in Solid Tumors (version 1.1), an Eastern Cooperative Oncology Group performance status of 0 or 1, life expectancy of 12 weeks or longer, and adequate healthy organ and bone marrow function. Initially, all patients received one 3-week cycle of gemcitabine (1000 mg/m²) and cisplatin (25 mg/m²) on day 1 and 8 followed by gemcitabine and cisplatin plus durvalumab (1120 mg) and tremelimumab (75 mg) on day 1 of each cycle, starting with the second cycle (chemotherapy followed by chemotherapy plus durvalumab and tremelimumab group). Following protocol amendment, patients were recruited to receive gemcitabine and cisplatin plus durvalumab, starting on day 1 of the first cycle (chemotherapy plus durvalumab group) or gemcitabine and cisplatin plus durvalumab and tremelimumab also from day 1 of the first cycle (chemotherapy plus durvalumab and tremelimumab group) in parallel and allocated using a random block method. Assessors and patients were not masked to the treatment group. The primary endpoint was objective response rate, assessed in the efficacy population (ie, patients who were treated at least until the first tumour response assessment). This study is registered with ClinicalTrials.gov, NCT03046862 (active).

FINDINGS

Between March 2, 2017, and Feb 13, 2020, 128 patients were enrolled (32 in the chemotherapy followed by chemotherapy plus durvalumab and tremelimumab group, 49 in the chemotherapy plus durvalumab group, and 47 in the chemotherapy plus durvalumab and tremelimumab group). Four patients (two in the chemotherapy followed by chemotherapy plus durvalumab and tremelimumab group and two in the chemotherapy plus durvalumab group) were excluded and 124 were evaluable for tumour response. The median duration of follow-up was 48·2 months (IQR 41·5-49·4) for the chemotherapy followed by chemotherapy plus durvalumab and tremelimumab group, 26·6 months (19·0-27·9) for the chemotherapy plus durvalumab group, and 24·2 months (20·7-31·7) for the chemotherapy plus durvalumab and tremelimumab group. 82 (66%) of 124 patients achieved an objective response (15 [50%] of 30 in the chemotherapy followed by chemotherapy plus durvalumab and tremelimumab group, 34 [72%] of 47 in the chemotherapy plus durvalumab group, and 33 [70%] of 47 in the chemotherapy plus durvalumab and tremelimumab group). The most common grade 3 and 4 adverse events were decreased neutrophil count (67 [53%] of 126), anaemia (50 [40%]), and decreased platelet count (24 [19%]), with no unexpected safety events. No adverse events leading to discontinuation or death occurred.

INTERPRETATION

Gemcitabine and cisplatin plus immunotherapy showed promising efficacy and acceptable safety in patients with biliary tract cancer. Gemcitabine and cisplatin plus durvalumab are being evaluated in the phase 3, TOPAZ-1 study (NCT03875235) as first-line treatment in patients with advanced biliary tract cancer.

FUNDING

AstraZeneca; National Research Foundation of Korea (Grant No. 2021R1A2C2007430).

Abstract 390: Identification of a novel immunosuppressive myeloid gene expression signature for clinical biomarker development

Cell-type abundance GE signatures are useful for informing drug mechanism of action and may be useful in-patient selection for cancer immunotherapies. Recently, we validated natural killer cell- and dendritic cell-type specific expression signatures using a tiered strategy that included both computational and ex vivo validation. Here, we built upon this strategy to validate expression signatures for immunosuppressive myeloid cells (IMC). IMC play a critical role in impairing anti-tumor immunity and increased levels of peripheral IMC have been associated with advanced tumor progression and poor prognosis in various cancers. However, their low abundance in normal tissues and heterogeneous surface expression render their profiling difficult. To address this, we focused on validating GE signatures for IMC abundance using mRNA expression methods which are more clinically tractable than established flow cytometry methods that require intact cells.

We implemented a three-stage GE signature validation strategy. First, we generated GE data from human ex vivo differentiated IMC (LIN- CD11B+ CD33+ HLADR-). Then, we evaluated the concordance of 16 previously published myeloid signatures with cell type abundance in a series of spike-ins with varying but known quantities of ex vivo differentiated IMC in a background of undifferentiated peripheral blood mononuclear cells (PBMCs). Gene-set variation analysis (GSVA) was used to score the signatures and Spearman's rank (rS) correlation coefficient was calculated to assess the significance of correlations between GSVA scores and IMC abundance. With this method, we validated 3 of the 16 published myeloid signatures (1. MacB3/PMID:26873985 (rS = 0.87; p = 8.8e-07); 2. MacB2_3w/PMID:26873985 (rS = 0.83; p = 6.7e-06); 3. TAM/PMID:27424807 (rS = 0.80; p= 2.6e-05)).

Next, we generated a ‘de novo' signature by performing differential GE analysis and identified up-regulated genes in IMC in comparison to PBMCs with log2 fold change &gt 2, p-adj &lt 0.05). We further refined this list by selecting genes with significant concordance to IMC abundance (rS &gt 0.80, p-adj &lt 0.05) and confirmed their specificity to IMC in published scRNAseq studies [PMID: 30979687; 31033233; 32302573]. This led to a 6-gene ‘de novo' signature (MRC1, APOE, C1QA, C1QB, MMP9, SPP1) associated with IMC function with highly significant concordance (rS = 0.96; p = 1.2e-11) to IMC abundance.

Lastly, we showed that in whole blood baseline samples from HNSCC patients (n=53) treated with danvatirsen + durvalumab [NCT02499328], our ‘de novo' signature was significantly elevated (p=0.033) in patients with progressive disease compared to complete responders. Application to additional studies will be required to more fully determine its clinical utility.

Citation Format: Srimathi S. Srinivasan, Gozde Kar, Deanna L. Russell, Peter Gathungu, Minoo Rafati, David Whitston, Grant Duclos, Ben Sidders, J Carl Barrett, Tim Slidel, Patricia McCoon. Identification of a novel immunosuppressive myeloid gene expression signature for clinical biomarker development [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 390.

T-cell receptor pharmacodynamics associated with survival and response to tremelimumab (T) in combination with durvalumab (D) in patients (pts) with unresectable hepatocellular carcinoma (uHCC)

4087

Background: Study 22, a phase 2 clinical study (NCT02519348) evaluating T (anti-CTLA-4) and D (anti-PD-L1) as monotherapies and in combination indicated the best efficacy-safety profile with a novel combination regimen containing a single, priming dose of T (T300+D). Additionally, an expansion of proliferative CD8+ lymphocytes at Day 15 was observed with T300+D that was associated with improved response. Here, an exploratory molecular analysis of peripheral blood T cell receptors is presented. Methods: Immune-checkpoint inhibitor-naïve pts were randomized to 1 of 2 T+D combinations: T300+D (T 300 mg [1 dose] + D 1500 mg, then D every 4 weeks [Q4W]) or T75+D (T 75 mg Q4W + D 1500 mg Q4W [4 doses], then D Q4W); or single agent D (1500 mg Q4W) or T (750 mg Q4W [7 doses] then Q12W). DNA was isolated from PAXgene-preserved whole blood collected at baseline and on Day 29 during the first cycle of Q4W dosing, and then underwent CDR3 sequencing of T-cell receptor β using the immunoSEQ Assay (Adaptive Biotechnologies, Seattle, WA). Associations with objective response rate (ORR) and overall survival (OS) were evaluated. Results: The number of evaluable pts, samples, and overall ORR and OS are provided (Table). Immunosequencing analysis did not reveal significant differences in baseline T-cell clonality across arms. Increased T-cell clonal expansion at Day 29 appeared to be T dose dependent (Table), with no significant difference in the median expansion between the D and T75+D arms. Across all arms, responders had a larger median number of expanded T-cell clones on Day 29 than nonresponders (77.5 vs 40), and this greater expansion trended with longer OS (Table). Further evaluation by arm demonstrated an increase in T-cell clonal expansion in responders vs nonresponders in the T300+D arm. Pts with T-cell expansion above the median in the T300+D and T75+D arms also exhibited longer OS. Both newly expanded and total expanded clones on Day 29 vs Day 1 were associated with improved OS. Conclusions: The observed T dose-dependent increase in T-cell clonal expansion trended with improved ORR and longer OS, with the greatest overall benefit seen with T300+D vs T75+D, D and T. This is consistent with the previously reported observation that T300+D led to the highest median proliferating CD8+ T-cell counts and radiographic response. Further work is needed to differentiate the relative contributions of CD4 and CD8 clonal expansion to increased efficacy. T300+D and D are being evaluated in the phase 3 HIMALAYA study (NCT03298451) in uHCC vs sorafenib. Funding: AstraZeneca. Clinical trial information: NCT02519348. [Table: see text]

Exposure-response (E-R) efficacy and safety (E-S) analyses of tremelimumab as monotherapy or in combination with durvalumab in patients (pts) with unresectable hepatocellular carcinoma (uHCC)

313

Background: In a phase II study in uHCC (Study 22, NCT02519348), a novel, priming combination regimen of tremelimumab (T; anti-CTLA-4) and durvalumab (D; anti-PD-L1) (T300+D) has shown favorable clinical activity vs each agent as monotherapy or vs another combination (T75+D). The analyses presented here assess the pharmacokinetics (PK) and relationships between tremelimumab exposure, as monotherapy or in combination, and safety, efficacy, and pharmacodynamics (PD) in this study. Methods: Overall, 216 pts were included in these analyses (T, n=65; T300+D, n=72; T75+D, n=79). Safety, antitumor activity, PK, PD, and immunogenicity were analyzed using standard pharmacometrics methods. A previously developed population PK model for T across solid tumors was validated using T monotherapy and combination therapy data from Study 22, including a post-hoc covariate analysis to assess the impact of covariates on individual PK parameters. Population PK and PD models related individual T exposures to safety parameters, PD, and efficacy (overall survival, OS; progression-free survival, PFS; and objective response rate, ORR). The E-R relationships for time-to-event variables OS and PFS were explored by Kaplan-Meier estimates and analyzed by Cox proportional-hazards models (CPHM). Results: For T monotherapy and T+D combinations, no significant E-S relationships were observed for grade 3/4 treatment-related adverse events (TRAEs), grade 3/4 TRAEs of special interest, and AEs leading to treatment discontinuation. Analyses of each quartile of T exposure suggest pts with higher exposure (3rd and 4th quartile) may have longer OS vs lower quartiles. The CPHManalysis showed that after accounting for prognostic factors (baseline albumin and neutrophil-to-lymphocyte ratio), neither AUC nor Cmin appeared to be a significant factor for OS hazard. There was no significant relationship between response and ORR, PFS and any T PK exposure metric in T-treated pts. Saturable relationships (described by Emax) were observed for maximum change from baseline for proliferating T-cell counts as functions of exposure. Conclusions: The observed PK data are generally consistent with predictions based on a historical population PK model, suggesting the PK of T in uHCC pts is consistent with pts with other solid tumors. No significant relationships were observed between E-S and E-R; therefore, PK is not a significant predictor to evaluate for T efficacy or safety. Considering the small sample size limitation, still the saturable relationships observed in proliferating T-cells appear to support a dose of T300. Future studies of pooled data from Study 22 and the larger phase III HIMALAYA study (NCT03298451) will be conducted to further the characterization of E-R relationships and the development of the T300+D regimen. Clinical trial information: NCT02519348.

STAT3 Antisense Oligonucleotide Remodels the Suppressive Tumor Microenvironment to Enhance Immune Activation in Combination with Anti-PD-L1

PURPOSE

Danvatirsen is a therapeutic antisense oligonucleotide (ASO) that selectively targets STAT3 and has shown clinical activity in two phase I clinical studies. We interrogated the clinical mechanism of action using danvatirsen-treated patient samples and conducted back-translational studies to further elucidate its immunomodulatory mechanism of action.

EXPERIMENTAL DESIGN

Paired biopsies and blood samples from danvatirsen-treated patients were evaluated using immunohistochemistry and gene-expression analysis. To gain mechanistic insight, we used mass cytometry, flow cytometry, and immunofluorescence analysis of CT26 tumors treated with a mouse surrogate STAT3 ASO, and human immune cells were treated in vitro with danvatirsen.

RESULTS

Within the tumors of treated patients, danvatirsen uptake was observed mainly in cells of the tumor microenvironment (TME). Gene expression analysis comparing baseline and on-treatment tumor samples showed increased expression of proinflammatory genes. In mouse models, STAT3 ASO demonstrated partial tumor growth inhibition and enhanced the antitumor activity when combined with anti-PD-L1. Immune profiling revealed reduced STAT3 protein in immune and stromal cells, and decreased suppressive cytokines correlating with increased proinflammatory macrophages and cytokine production. These changes led to enhanced T-cell abundance and function in combination with anti-PD-L1.

CONCLUSIONS

STAT3 ASO treatment reverses a suppressive TME and promotes proinflammatory gene expression changes in patients' tumors and mouse models. Preclinical data provide evidence that ASO-mediated inhibition of STAT3 in the immune compartment is sufficient to remodel the TME and enhance the activity of checkpoint blockade without direct STAT3 inhibition in tumor cells. Collectively, these data provide a rationale for testing this combination in the clinic.

Abstract LB-105: Plasma exposure-target engagement biomarker analysis for danvatirsen after multiple dosing schedules and route of administrations in patients with advanced solid tumors

Background: Danvatirsen (Da) is a generation 2.5 antisense oligonucleotide targeting STAT3 mRNA under clinical development in combination with Durvalumab (NCT03421353). The recommended Phase II dose is intravenous (IV) 200 mg weekly (QW, A). However, alternative 400 mg IV every two weeks (Q2W, B) and subcutaneous 200 mg QW (C) are also under investigation. The JAK-STAT signaling pathway is involved in immunity, cell division, cell death, and tumor formation. Additionally, activation of hepatic STAT3 results in increased secretion of C-reactive protein (CRP) and fibrinogen into blood. Therefore, target engagement in patients may be better understood by analyzing Da exposure and related biomarkers in the blood/plasma. We investigated Da exposure and subsequent impact on target engagement biomarkers such as CRP, platelets, fibrinogen, neutrophils and STAT3 mRNA levels. Methods: Extensive pharmacokinetics (PK) samples were collected at lead-in monotherapy and at steady state (SS) in combination. Plasma biomarker samples were collected at baseline and every two weeks thereafter. Whole blood samples for the analysis of STAT3 mRNA were collected at baseline, after lead-in monotherapy, and every four weeks thereafter. The PK parameters were estimated by non-compartmental analysis by WinNonlin. The biomarkers were analyzed by standard clinical methods and STAT3 mRNA level was measured by NanoString technology. Results: The area under plasma concentration-time curve of Da at SS within dosing interval (AUC0-τ, ng.h/ml) for A, B, and C were 69110 (24.64%), 101600 (22.11%), and 44600 (30.25%), respectively. Additionally, SS Ctrough (ng/ml) levels for A, B, and C were 28.53 (48.86%), 14.56 (36.14%), and 27.66 (49.22%), respectively. Maximum median % decrease from baseline in CRP levels was observed at week 4; A (-91%), B (-94%), C (-82%). Additionally, maximum median % changes from baseline for fibrinogen were -60%, -40%, -53%, in A, B, and C at week 4, respectively. Maximum % decrease from baseline in platelets was observed at week 8 in A (-42%), B (-41%), and C (-69%). In contrast, maximum % change from baseline in neutrophil count was observed at week 6; -37%, -31%, and -32% in A, B, and C, respectively. Additionally, the median maximum change from baseline for STAT3 mRNA was -42.4% and -33.6% for A and C, respectively. Conclusion: Cumulative AUC in A was very similar to B, whereas, AUC in C was 30% lower as compared to A or B. The SS Ctrough values in A and C were similar, although Ctrough value in B was 50% lower. Maximum % decreases in CRP levels were similar across all the doses. Moreover, route of administration did not appear to impact level of STAT3 knockdown. In summary, a similar degree of changes in pharmacodynamic biomarkers were achieved at all three dose levels regardless of route of administration, despite differences in plasma exposure.

Citation Format: Kowser Miah, Patricia McCoon, Deanna Russell, Patrick Mitchell, Martin Scott, Amy Rosenfeld, Li Zhang, Pablo Martinez Rodriguez, Alicia Savage, Ganesh Mugundu. Plasma exposure-target engagement biomarker analysis for danvatirsen after multiple dosing schedules and route of administrations in patients with advanced solid tumors [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr LB-105.

STAT3 antisense oligonucleotide AZD9150 in a subset of patients with heavily pretreated lymphoma: results of a phase 1b trial

Background

The Janus kinase (JAK) and signal transduction and activation of transcription (STAT) signaling pathway is an attractive target in multiple cancers. Activation of the JAK-STAT pathway is important in both tumorigenesis and activation of immune responses. In diffuse large B-cell lymphoma (DLBCL), the transcription factor STAT3 has been associated with aggressive disease phenotype and worse overall survival. While multiple therapies inhibit upstream signaling, there has been limited success in selectively targeting STAT3 in patients. Antisense oligonucleotides (ASOs) represent a compelling therapeutic approach to target difficult to drug proteins such as STAT3 through of mRNA targeting. We report the evaluation of a next generation STAT3 ASO (AZD9150) in a non-Hodgkin’s lymphoma population, primarily consisting of patients with DLBCL.

Methods

Patients with relapsed or treatment refractory lymphoma were enrolled in this expansion cohort. AZD9150 was administered at 2 mg/kg and the 3 mg/kg (MTD determined by escalation cohort) dose levels with initial loading doses in the first week on days 1, 3, and 5 followed by weekly dosing. Patients were eligible to remain on therapy until unacceptable toxicity or progression. Blood was collected pre- and post-treatment for analysis of peripheral immune cells.

Results

Thirty patients were enrolled, 10 at 2 mg/kg and 20 at 3 mg/kg dose levels. Twenty-seven patients had DLBCL. AZD9150 was safe and well tolerated at both doses. Common drug-related adverse events included transaminitis, fatigue, and thrombocytopenia. The 3 mg/kg dose level is the recommended phase 2 dose. All responses were seen among DLBCL patients, including 2 complete responses with median duration of response 10.7 months and 2 partial responses. Peripheral blood cell analysis of three patients without a clinical response to therapy revealed a relative increase in proportion of macrophages, CD4+, and CD8+ T cells; this trend did not reach statistical significance.

Conclusions

AZD9150 was well tolerated and demonstrated efficacy in a subset of heavily pretreated patients with DLBCL. Studies in combination with checkpoint immunotherapies are ongoing.

Trial registration

Registered at ClinicalTrials.gov: NCT01563302. First submitted 2/13/2012.

Electronic supplementary material

The online version of this article (10.1186/s40425-018-0436-5) contains supplementary material, which is available to authorized users.

Antisense STAT3 inhibitor decreases viability of myelodysplastic and leukemic stem cells

Acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) are associated with disease-initiating stem cells that are not eliminated by conventional therapies. Transcriptomic analysis of stem and progenitor populations in MDS and AML demonstrated overexpression of STAT3 that was validated in an independent cohort. STAT3 overexpression was predictive of a shorter survival and worse clinical features in a large MDS cohort. High STAT3 expression signature in MDS CD34+ cells was similar to known preleukemic gene signatures. Functionally, STAT3 inhibition by a clinical, antisense oligonucleotide, AZD9150, led to reduced viability and increased apoptosis in leukemic cell lines. AZD9150 was rapidly incorporated by primary MDS/AML stem and progenitor cells and led to increased hematopoietic differentiation. STAT3 knockdown also impaired leukemic growth in vivo and led to decreased expression of MCL1 and other oncogenic genes in malignant cells. These studies demonstrate that STAT3 is an adverse prognostic factor in MDS/AML and provide a preclinical rationale for studies using AZD9150 in these diseases.

Abstract B83: Intratumoral T cell receptor β repertoire as a biomarker in head and neck squamous cell carcinoma

In this study, we examine the T cell receptor (TCR) repertoire in a cohort of Head and Neck Squamous Cell Carcinoma (HNSCC) patients (n=50) at time of diagnosis. The TCR repertoire is indicative of the ability of the body to mount an immune response, with increased productive clonality within the tumor environment suggesting accumulation of tumor antigen specific T cells. Recent studies demonstrate that the intratumoral TCR repertoire is prognostic of response to anti-PD-1 (Tumeh et al., 2014) and anti-CTLA-4 (Page et al., 2016) therapies. Here we examine diversity and clonality of intratumoral T cell β repertoires in HNSCC patients independently and in conjunction with other biomarkers including tumor mutational burden/neoantigen load, expression of inhibitory checkpoints, and characterization of immune cell populations, as well as clinical metadata including HPV status, smoking history, and survival outcomes. The TCRβ repertoire was analyzed from FFPE primary tumor samples through targeted next generation DNA sequencing of the TCRβ loci and examination of the CDR3 sequences to determine clonality of the TCRβ repertoire (1 – Pielou’s evenness). Somatic genomic alterations, tumor mutational burden, and HLA typing were conducted through whole exome sequencing. Inhibitory checkpoint expression and characterization of immune cell populations were conducted through immunohistochemistry, RNA expression, or both methods. Preliminary results indicate productive clonality of the TCR repertoire in the range of 0.03-0.16. In examining HPV+ and HPV- patients, where we hypothesize the presentation of foreign peptides of viral etiology will produce an increase in T cell populations recognizing those neoantigens, we see no difference in either T cell infiltration or productive clonality. However, we observe that PD-L1 status is significantly correlated (p &lt; 0.05) to productive clonality of the tumor infiltrating T cells, with a higher average productive clonality in PD-L1+ patients. Ongoing studies will characterize the landscape of somatic genomic alterations including tumor mutational burden, and gene expression profiles of the tumor microenvironment.

Citation Format: Lara McGrath, Elizabeth Maloney, Maria Secrier, Helen Angell, Emma Jones, Brian Dougherty, Daniel Stetson, Patricia McCoon, Andrew Pierce, Craig Barker, Carl Barrett. Intratumoral T cell receptor β repertoire as a biomarker in head and neck squamous cell carcinoma [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2017 Oct 1-4; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2018;6(9 Suppl):Abstract nr B83.

Abstract 3684: Inhibition of STAT3 by antisense oligonucleotide treatment decreases the immune suppressive tumor microenvironment in syngeneic and GEM tumor models

AZD9150, a gen2.5 antisense oligonucleotide (ASO) targeting human STAT3, has improved drug-like properties compared to previous generation ASO therapeutics, including increased stability and resistance to nucleases, reduced proinflammatory effects, and enhanced potency. We have previously reported that in tumors, STAT3 ASOs are taken up preferentially in stromal and immune cells of the tumor microenvironment (TME). Since AZD9150 is selective for human STAT3, we used a surrogate ASO (muSTAT3 ASO) to explore the pharmacodynamics of ASO-mediated STAT3 inhibition in syngeneic and genetically engineered mouse (GEM) tumor models, focusing on effects in the TME.

In mice bearing subcutaneous CT-26 tumors, treatment with muSTAT3 ASO at 50 mg/kg, s.c., on a qdx5/wk schedule decreased STAT3 levels in immune cell subsets in the tumor and in circulating leukocytes by 40 - 60%, similar to the decrease in STAT3 achievable in circulating leukocytes in human patients after AZD9150 treatment.

In a Nanostring analysis (nCounter mouse immunology panel) of CT-26 tumors from muSTAT3 ASO treated mice, CD163 (M2 immune suppressive macrophage marker) was the gene most consistently and significantly downregulated, by an average of 84% in three independent experiments, and was confirmed by immunohistochemistry (IHC). Flow cytometry analysis of myeloid subpopulations - tumor associated macrophages (F4/80+ TAMs), monocytic myeloid derived suppressor cells, and granulocytic cells - showed a decrease in TAMs averaging 69% across three independent experiments. The analysis was extended to include IHC for arginase (Arg, a marker of functional immune suppression activity). Subpopulations of cells identified included Arg+, CD163+, and Arg+CD163+. Treatment with muSTAT3 ASO decreased these populations by 79%, 88% and 97% respectively, compared to control treatment. These populations were also analyzed in two GEM tumor models - the KPC pancreatic cancer model, and a PTEN -/- prostate cancer model - which have a TME more representative of that found in tumors in the clinic. While the specific changes varied across the models, likely reflecting differences in TME makeup, a reduction in immune suppressive cell populations was present in both GEM models, including a decrease in CD163+ cells of 79% (along with modest antitumor activity) in the PTEN -/- prostate model after muSTAT3 ASO treatment.

These results indicate that selective STAT3 inhibition can reduce immune suppressive cell populations in the TME, and suggest that STAT3 inhibition has the potential to enhance the antitumor activity of T-cell targeted therapies, such as those targeting the PD1-PDL1 axis. In support of this hypothesis, we observed that addition of muSTAT3 ASO to anti-PD-L1 Ab treatment significantly enhanced the antitumor activity of PD-L1 Ab treatment in two subcutaneous syngeneic tumor models, CT-26 and A20.

Citation Format: Rich Woessner, Vasu Sah, Patricia McCoon, Shaun Grosskurth, Nanhua Deng, Rachel DuPont, Deborah Lawson, Lourdes Pablo, Corinne Reimer, Marco A. De Velasco, Hirotsugu Uemura, Juliana Candido, Paul Lyne. Inhibition of STAT3 by antisense oligonucleotide treatment decreases the immune suppressive tumor microenvironment in syngeneic and GEM tumor models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3684. doi:10.1158/1538-7445.AM2017-3684

Abstract 2641: AZD4635 A2A receptor occupancy in cynomolgus monkey using PET and its application to an oncology clinical development program

Introduction

AZD4635 is an A2A receptor antagonist currently being tested as monotherapy and in combination with durvalumab in patients with advanced solid cancers. High adenosine levels found in tumors are immune suppressive and therefore AZD4635 could potentiate immune checkpoint inhibitors such as durvalumab (anti-PDL1). Predictions of A2A receptor engagement in patients at different doses and at different time points may enable better interpretation of clinical biomarker data measuring effects on immune modulation. A quantitative assessment of the receptor occupancy in the brain of non-human primates was conducted for AZD4635 with PET imaging and the resulting PK/PD model was applied to predict occupancy in humans in tumors.

Methods

PET measurements of A2AR occupancy in brain was performed using the radioligand [18F]MNI-444 in three anesthetized cynomologus monkeys. PET data acquisition was performed for 120 min following IV-administration of [18F]MNI-444 at baseline and following pretreatment of AZD4635. Sampling for AZD4635 plasma exposure determination was performed. As part of PK/PD analysis of the occupancy data, a novel modification of the non Invasive-LOGAN data analysis of the PET data was performed to obtain a time course of occupancy for each dose. A bio-phase PK/PD mathematical model was then used to describe the relationship of occupancy with circulating concentrations of AZD4635. In parallel, a PK model for AZD4635 in humans was developed using data from cohort 1 (Clinical trial NCT02740985) after 125 mg and used for PK predictions for alternative doses of AZD4635 in the clinic.

Results

A clear Exposure-Effect relationship was observed for AZD4635-driven A2AR occupancy in cyno brain when dosed 30 min prior to PET measurement. The PK/PD analysis of cyno PET-determined receptor occupancy provided an Occ50 that is in line with the in vitro potency for the compound under physiological concentrations of adenosine in the brain. The resulting PK/PD model has then been applied to predict the level of occupancy in human tumours at other clinically relevant doses. Different simulations were done varying the amount of endogenous adenosine levels.

Conclusions

AZD4635 was shown to occupy A2AR in cyno brain in an exposure dependent manner. The resulting PK/PD model built using this dataset was used to run simulations of expected tumor receptor occupancy in man and aid clinical dose selection for AZD4635. Sensitivity analysis has shown that prediction of human occupancy in the tumour is highly dependent on adenosine concentrations in the tumour. Simulations with tumor adenosine concentrations of 1 μM indicate that AZD4635 is predicted to provide ~90% receptor occupancy over the whole dosing interval at a clinically relevant dose.

Citation Format: Peter Johnström, Pablo Morentin Gutierrez, Katarina Varnäs, Magnus Schou, Akihiro Takano, Lorraine Jones, Ganesh Mugundu, Patricia McCoon, Paul Lyne, Jeffrey Infante, Gerald Falchook, Manish Patel, Janet Karlix, Melinda Merchant, James Clarke, Alan Cross, Nicholas Seneca, Lars Farde, Miles Congreve, Jon S. Mason, Fiona H. Marshall. AZD4635 A2A receptor occupancy in cynomolgus monkey using PET and its application to an oncology clinical development program [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2641. doi:10.1158/1538-7445.AM2017-2641

Abstract A93: STAT3 inhibition enhances the activity of immune checkpoint inhibitors in murine syngeneic tumor models by creating a more immunogenic tumor microenvironment

The multifaceted role of STAT3 in enhancing tumor growth by tumor cell intrinsic as well as extrinsic (stromal and immune modulatory) mechanisms is well documented. Elevated STAT3 in tumor cells can lead to increased expression of cytokines, such as IL-6, which can create an immune suppressive environment in the tumor stroma. In addition, STAT3 signaling in cells of the immune system has the potential to contribute to an immune suppressive environment by several mechanisms, including suppression of dendritic cell (DC) maturation and function, enhanced myeloid derived suppressor cell (MDSC) activity, and suppression of T-cell mediated antitumor activity. An immune suppressive environment can reduce the antitumor activity of checkpoint inhibitors such as anti-PD-L1 antibodies by suppressing the ability of T-cell mediated immunity to respond to checkpoint reversal. Therefore, we hypothesized that inhibition of STAT3 has the potential to increase the anti-tumor effects of immune checkpoint inhibitors.

To investigate this hypothesis, we explored the ability of a mouse STAT3 targeted antisense oligonucleotide (ASO) to enhance the antitumor activity of an anti-PD-L1 mAb in a syngeneic murine tumor model. In mice bearing subcutaneous CT-26 tumors, the combination of the STAT3 ASO plus an anti-PD-L1 mAb provided greater antitumor activity than either agent alone. Increased activity was observed when treatment was initiated soon (2 days) after tumor implantation, as well as when treatment was initiated after tumors were established (~150 mm3). When treatment was initiated soon after tumor implantation, single agents as well as the combination were initially effective, but the combination led to long term suppression of tumor growth in a greater percentage of mice (80% for the combination, vs. 20% for single agents). When treatment was initiated after tumors were established, STAT3 ASO or anti-PD-L1 antibody as single agents had significant initial antitumor activity (55% after 14 days of treatment). However, the single agent activity was transient, with the tumor growth rate returning to that of vehicle control (5 day doubling time) after two weeks of treatment. In contrast, the combination treatment led to a sustained reduction in mean tumor growth rate (15 days doubling time), and regression in 20 - 30% of tumors after four weeks of treatment. Treatment with the STAT3 ASO was associated with tumor infiltrating leukocyte changes consistent with enhanced antitumor immunity, including an increase in CD8+ effector T-cells. Combination benefit for STAT3 ASO plus anti-PD-L1 antibody was also observed in other immunocompetent murine tumor models.

The data indicate that, in these models, inhibition of STAT3 has immunomodulatory activity, and can enhance the activity of immune checkpoint inhibitors, such as those targeting PD-L1.

Citation Format: Rich Woessner, Patricia McCoon, Kirsten Bell, Rachel DuPont, Mike Collins, Deborah Lawson, Prasad Nadella, Lourdes Pablo, Corinne Reimer, Vasu Sah, Paul Lyne. STAT3 inhibition enhances the activity of immune checkpoint inhibitors in murine syngeneic tumor models by creating a more immunogenic tumor microenvironment. [abstract]. In: Proceedings of the AACR Special Conference: Tumor Immunology and Immunotherapy: A New Chapter; December 1-4, 2014; Orlando, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2015;3(10 Suppl):Abstract nr A93.

A phase I, open-label, multi-center study of the JAK2 inhibitor AZD1480 in patients with myelofibrosis

The anti-tumor activity of AZD1480, a potent, selective inhibitor of Janus-associated kinases 1 and 2, was demonstrated in preclinical models of myeloproliferative neoplasms. In a phase I clinical study, 35 patients with myelofibrosis received 2.5-70mg AZD1480 orally once daily (QD) or 10 or 15mg twice daily (BID) continuously during repeated 28-day cycles. Two patients experienced dose-limiting toxicities: one patient in the 2.5mg QD cohort had a grade 3 lung infiltration/acute pneumonia, and one patient receiving 50mg QD had grade 3 presyncope. Dosing was stopped at 70mg QD after the first patient experienced an adverse neurological event (AE) and evidence of low-grade neurological toxicity in patients on lower doses after the initial month of therapy became apparent. The most common AZD1480-related AEs were dizziness and anemia. AZD1480 was absorbed quickly and eliminated from the plasma rapidly, with a mean terminal half-life of 2.45-8.06h; accumulation was not observed after repeated daily dosing for 28 days. Four patients showed evidence of clinical improvement based on IWG-MRT 2006 criteria. AZD1480 was relatively well tolerated, however, low-grade, reversible neurological toxicity was therapy limiting and led to study termination.

AZD1480: a phase I study of a novel JAK2 inhibitor in solid tumors

BACKGROUND

AZD1480 is a novel agent that inhibits Janus-associated kinases 1 and 2 (JAK1 and JAK2). The primary objective of this phase I study was to investigate the safety and tolerability of AZD1480 when administered as monotherapy to patients with solid tumors.

METHODS

Thirty-eight patients with advanced malignancies were treated at doses of 10-70 mg once daily (QD) and 20-45 mg b.i.d.

RESULTS

Pharmacokinetic (PK) analysis revealed rapid absorption and elimination with minimal accumulation after repeated QD or b.i.d. dosing. Exposure increased in a dose-dependent manner from 10-50 mg. Maximum plasma concentration (Cmax) was attained ∼1 hour after dose, and t1/2 was ∼5 hours. Pharmacodynamic analysis of circulating granulocytes demonstrated maximum phosphorylated STAT3 (pSTAT3) inhibition 1-2 hours after dose, coincident with Cmax, and greater pSTAT3 inhibition at higher doses. The average pSTAT3 inhibition in granulocytes at the highest dose tested, 70 mg QD, was 56% (standard deviation: ±21%) at steady-state drug levels. Dose-limiting toxicities (DLTs) consisted of pleiotropic neurologic adverse events (AEs), including dizziness, anxiety, ataxia, memory loss, hallucinations, and behavior changes. These AEs were generally reversible with dose reduction or treatment cessation.

CONCLUSIONS

Whether the DLTs were due to inhibition of JAK-1/2 or to off-target effects is unknown. The unusual DLTs and the lack of clinical activity led to discontinuation of development.

Abstract 3516: AZD1208 PIM kinase inhibitor - Preliminary evidence of target pathway inhibition in Phase I clinical trials of AML

PIM kinases have been shown to play a key role as downstream effectors of growth factor signalling pathways including Flt3 and the Jak-STAT signalling pathways in AML, NHL and other solid tumors. AZD1208 is a novel, orally bioavailable, highly selective PIM kinase inhibitor with single nanomolar potency against all three PIM kinases and is currently undergoing Phase I testing and dose escalation studies in AML. Here we describe a multiplexed biomarker strategy measuring pBAD, p4EBP1 and p-p70S6K as downstream pharmacodynamic biomarkers for PIM kinase inhibition in clinical trials. Patient bone marrow aspirates and peripheral blood samples were collected pre- and post-AZD1208 treatment in AML patients during the Phase I dose escalation and expansions. Primary patient samples were analyzed for quantitative changes in pBAD, p4EBP1 by NanoPro and MesoScale assay platforms as well as a qualitative evaluation of p-p70S6K and other exploratory endpoints. Preclinical PK-PD modeling data with AZD1208 had suggested that greater than a 50% decrease in the levels of one of these phosphorlyated substrates would be indicative of efficacy and PIM pathway inhibition. Following a single dose of AZD1208 at 120mg, the first dose level, approximately 60-70% inhibition of pBAD, S112 was seen in the bone marrow and peripheral blasts. Taken together, the data presented here provide evidence for single agent AZD1208 activity in AML patients based on quantitative reduction in these biomarkers. Correlations of these biomarker endpoints with Phase I pharmacokinetic data underscore the therapeutic potential of Pim kinase inhibition by AZD1208 for the treatment of AML, and strongly support further investigation of this agent in other indications where PIM signaling may play a role in tumorigenesis and survival.

Citation Format: Kristen A. McEachern, Yichen Cao, Rachel DuPont, Lourdes Pablo, Patricia McCoon, Jorge E. Cortes, Daniel J. DeAngelo, Mark D. Minden, Becker Hewes, Jeffrey L. Brown, Carl Barrett. AZD1208 PIM kinase inhibitor - Preliminary evidence of target pathway inhibition in Phase I clinical trials of AML. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3516. doi:10.1158/1538-7445.AM2013-3516

Abstract 4429: Characterization of the kinesin spindle protein inhibitor AZD4877

The process of mitosis is a validated point of intervention in cancer therapy and a variety of anti-mitotic drugs are successfully being used in the clinic. To date, all approved antimitotics target the spindle microtubules, thus interfering with spindle dynamics, leading to mitotic arrest and apoptosis. While effective, these drugs are also associated with a variety of side effects, including neurotoxicity. In recent years, mitotic kinesins have attracted significant attention in the search for novel, alternative mitotic drug targets. In addition, kinesin inhibitors may overcome resistance to microtubule targeting drugs.

Here we describe the pharmacological evaluation of AZD4877, a selective Eg5 inhibitor. AZD4877 exhibits potent cell growth inhibition in vitro against a broad panel of both solid and hematological tumor cell lines. Efficacy is associated with formation of monoastral spindles, mitotic block and the induction of apoptosis. AZD4877 also demonstrates activity in multiple tumor xenograft models, including primary bladder tumor explants and a Rituximab-insensitive non-Hodgkin's Lymphoma model (DoHH2T53). Combination studies with a taxane agent (Docetaxel) demonstrate additive efficacy of tumor growth inhibition, with notable tumor regrowth delay in the combination arm. In summary, AZD4877 is an active Eg5 inhibitor with potent anti-tumor activities in vitro and in vivo. The efficacy observed in combination studies and in a rituximab-resistant tumor model suggests possible clinical applications for this agent.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4429.

A human monoclonal anti-ANG2 antibody leads to broad antitumor activity in combination with VEGF inhibitors and chemotherapy agents in preclinical models

Localized angiopoietin-2 (Ang2) expression has been shown to function as a key regulator of blood vessel remodeling and tumor angiogenesis, making it an attractive candidate for antiangiogenic therapy. A fully human monoclonal antibody (3.19.3) was developed, which may have significant pharmaceutical advantages over synthetic peptide-based approaches in terms of reduced immunogenicity and increased half-life to block Ang2 function. The 3.19.3 antibody potently binds Ang2 with an equilibrium dissociation constant of 86 pmol/L, leading to inhibition of Tie2 receptor phosphorylation in cell-based assays. In preclinical models, 3.19.3 treatment blocked blood vessel formation in Matrigel plug assays and in human tumor xenografts. In vivo studies with 3.19.3 consistently showed broad antitumor activity as a single agent across a panel of diverse subcutaneous and orthotopic xenograft models. Combination studies of 3.19.3 with cytotoxic drugs or anti-vascular endothelial growth factor agents showed significant improvements in antitumor activity over single-agent treatments alone with no apparent evidence of increased toxicity. Initial pharmacokinetic profiling studies in mice and nonhuman primates suggested that 3.19.3 has a predicted human half-life of 10 to 14 days. These studies provide preclinical data for 3.19.3 as a potential new antiangiogenic therapy as a single agent or in combination with chemotherapy or vascular endothelial growth factor inhibitors for the treatment of cancer.

The JAK2 inhibitor AZD1480 potently blocks Stat3 signaling and oncogenesis in solid tumors

Persistent activation of Stat3 is oncogenic and is prevalent in a wide variety of human cancers. Chronic cytokine stimulation is associated with Stat3 activation in some tumors, implicating cytokine receptor-associated Jak family kinases. Using Jak2 inhibitors, we demonstrate a central role of Jaks in modulating basal and cytokine-induced Stat3 activation in human solid tumor cell lines. Inhibition of Jak2 activity is associated with abrogation of Stat3 nuclear translocation and tumorigenesis. The Jak2 inhibitor AZD1480 suppresses the growth of human solid tumor xenografts harboring persistent Stat3 activity. We demonstrate the essential role of Stat3 downstream of Jaks by inhibition of tumor growth using short hairpin RNA targeting Stat3. Our data support a key role of Jak kinase activity in Stat3-dependent tumorigenesis.

Epitope-dependent effect of anti-murine TIM-1 monoclonal antibodies on T cell activity and lung immune responses

The TAPR locus containing the TIM gene family is implicated in the development of atopic inflammation in mouse, and TIM-1 allelic variation has been associated with the incidence of atopy in human patient populations. In this study, we show that manipulation of the TIM-1 pathway influences airway inflammation and pathology. Anti-TIM-1 mAbs recognizing distinct epitopes differentially modulated OVA-induced lung inflammation in the mouse. The epitopes recognized by these Abs were mapped, revealing that mAbs to both the IgV and stalk domains of TIM-1 have therapeutic activity. Unexpectedly, mAbs recognizing unique epitopes spanning exon 4 of the mucin/stalk domains exacerbated immune responses. Using Ag recall response studies, we demonstrate that the TIM-1 pathway acts primarily by modulating the production of T(H)2 cytokines. Furthermore, ex vivo cellular experiments indicate that TIM-1 activity controls CD4(+) T cell activity. These studies validate the genetic hypothesis that the TIM-1 locus is linked to the development of atopic disease and suggest novel therapeutic strategies for targeting asthma and other atopic disorders.

T cell, Ig domain, mucin domain-2 gene-deficient mice reveal a novel mechanism for the regulation of Th2 immune responses and airway inflammation

The development of asthma and other atopic diseases is influenced by cytokines produced by Th2 effector T cells. How effector T cell responses are regulated once these cell populations are established remains unclear. The recently described T cell and airway phenotype regulator locus, containing the T cell, Ig domain, mucin domain (TIM) genes, is genetically associated with Th2 cytokine production and Th2-dependent immune responses. In this study, we report the phenotype of the TIM-2 gene-deficient mouse, and demonstrate exacerbated lung inflammation in an airway atopic response model. Immune responses in the TIM-2-deficient mouse reveal disregulated expression of Th2 cytokines, and adoptive transfer experiments show that the T cell compartment is responsible for the heightened inflammatory phenotype. These studies show that TIM-2 is a novel and critical regulator of effector T cell activity.

A Drosophila derailed homolog, doughnut, expressed in invaginating cells during embryogenesis

Members of the RYK family of receptors are homologous to tyrosine kinases but do not exhibit kinase activity in vitro. We describe a new member of this family in Drosophila, which we call Doughnut (DNT). The protein product was found to be 70% identical to the Drosophila Derailed (DRL) protein and 35-40% identical to the mammalian RYK proteins. During Drosophila embryogenesis, DNT was found to be expressed in a highly dynamic pattern, including many invaginating cells. Many aspects of the expression pattern resembled that of unpaired, a gene that encodes a secreted protein that stimulates the Drosophila JAK/STAT signaling pathway. RYK proteins contain amino acid substitutions at residues that are highly conserved amongst proteins that exhibit kinase activity. Therefore, it has been unclear whether RYK family members are catalytically active or, if they are not, how they might transduce a signal. When expressed in cell culture DNT became phosphorylated on tyrosine, as did a mutant form of the receptor, containing an arginine residue in place of lysine within the predicted nucleotide binding site. These results suggest that DNT associates with a catalytically active kinase, but may not be capable of autophosphorylation.

Intraepithelial anchoring fibril components

Cultured human keratinocytes and cultured human cervical carcinoma cells (ME-180) contained intracellular pools of antigens that reacted with the anchoring fibril antibodies AF1 and AF2. In keratinocytes, these antigens formed a basement membrane-like structure near the apical portions of the cells. Using flow cytometric techniques, pretreatment of the ME-180 cells with acetone revealed large intracellular pools of antigen. The intracellular epitope was calcium sensitive. Some forms of recessive dystrophic epidermolysis bullosa have retention of intracellular portions of the anchoring fibril suggesting a relation of the intracellular anchoring fibril antigens to that disease.