Phase 1 first-in-human study of ABBV-184 monotherapy in adult patients with previously treated acute myeloid leukemia or non-small cell lung cancer

TPS2674

Background: Survivin, a member of the inhibitor of apoptosis protein family, is an attractive therapeutic target in cancer, due to its broad expression in solid tumors and hematologic malignancies but limited expression in normal tissues. Elevated survivin expression is associated with an increased invasive phenotype and worse clinical outcomes. ABBV-184 is a first-in-class T-cell receptor (TCR)/anti-cluster of differentiation 3 (CD3) bispecific molecule. It is composed of a soluble TCR that binds to a survivin-derived peptide bound to the class I MHC allele HLA-A2:01 expressed on tumor cells and to the CD3 receptor on T cells. Preclinical data have demonstrated that treatment with ABBV-184 results in T-cell activation, proliferation, and redirected cytotoxicity of HLA-A2:01–positive target cell lines. This first-in-human trial evaluates ABBV-184 monotherapy in patients with previously treated acute myeloid leukemia (AML) or non-small cell lung cancer (NSCLC). Methods: Patients (≥18 years, Eastern Cooperative Oncology Group performance status ≤2, HLA-A2:01 restricted genotype) with relapsed or refractory AML or NSCLC are currently enrolling in this phase 1 multicenter, open-label trial (NCT04272203), which includes parallel dose-escalation and dose-expansion phases for both diseases. Primary objectives are to determine the recommended phase 2 dose (RP2D) of ABBV-184 (dose escalation) and to assess its preliminary efficacy (dose expansion). Secondary objectives include safety, tolerability, pharmacokinetics (PK), and immunogenicity assessments (dose escalation and dose expansion) and duration of response (dose expansion). Patients will receive intravenous infusion of ABBV-184 once weekly. Dose escalation of ABBV-184 is guided by a Bayesian optimal interval design and the RP2D will be determined on the basis of clinical safety, PK, and pharmacodynamic data. For patients with AML, disease assessment is performed according to modified European LeukemiaNet-International Working Group criteria. For patients with NSCLC, response will be assessed using Response Evaluation Criteria In Solid Tumors (RECIST) v1.1 and immune RECIST. Treatment can continue until disease progression or intolerable toxicity. Biomarker assessments will include longitudinal profiling of peripheral blood immune cells and cytokines, analysis of HLA-A2 and survivin levels on AML bone marrow blasts and NSCLC tumor biopsies, and retrospective correlations of biomarker data with antitumor activity. Enrollment initiated in Sep 2020, with 7 patients enrolled as of Jan 2021. Clinical trial information: NCT04272203.

Phase I study of ABBV-428, a mesothelin-CD40 bispecific, in patients with advanced solid tumors

BACKGROUND

CD40 agonist immunotherapy can potentially license antigen-presenting cells to promote antitumor T-cell activation and re-educate macrophages to destroy tumor stroma. Systemic administration of CD40 agonists has historically been associated with considerable toxicity, providing the rationale for development of tumor-targeted immunomodulators to improve clinical safety and efficacy. This phase I study assessed the safety, tolerability, preliminary antitumor activity, and preliminary biomarkers of ABBV-428, a first-in-class, mesothelin-targeted, bispecific antibody designed for tumor microenvironment-dependent CD40 activation with limited systemic toxicity.

METHODS

ABBV-428 was administered intravenously every 2 weeks to patients with advanced solid tumors. An accelerated titration (starting at a 0.01 mg/kg dose) and a 3+3 dose escalation scheme were used, followed by recommended phase II dose cohort expansions in ovarian cancer and mesothelioma, tumor types associated with high mesothelin expression.

RESULTS

Fifty-nine patients were treated at doses between 0.01 and 3.6 mg/kg. The maximum tolerated dose was not reached, and 3.6 mg/kg was selected as the recommended phase II dose. Seven patients (12%) reported infusion-related reactions. Treatment-related grade ≥3 treatment-emergent adverse events were pericardial effusion, colitis, infusion-related reaction, and pleural effusion (n=1 each, 2%), with no cytokine release syndrome reported. The pharmacokinetic profile demonstrated roughly dose-proportional increases in exposure from 0.4 to 3.6 mg/kg. Best response was stable disease in 9/25 patients (36%) treated at the recommended phase II dose. CD40 receptor occupancy >90% was observed on peripheral B-cells starting from 0.8 mg/kg; however, no consistent changes from baseline in intratumoral CD8+ T-cells, programmed death ligand-1 (PD-L1+) cells, or immune-related gene expression were detected post-ABBV-428 treatment (cycle 2, day 1). Mesothelin membrane staining showed greater correlation with progression-free survival in ovarian cancer and mesothelioma than in the broader dose escalation population.

CONCLUSIONS

ABBV-428 monotherapy exhibited dose-proportional pharmacokinetics and an acceptable safety profile, particularly for toxicities characteristic of CD40 agonism, illustrating that utilization of a tumor-targeted, bispecific antibody can improve the safety of CD40 agonism as a therapeutic approach. ABBV-428 monotherapy had minimal clinical activity in dose escalation and in a small expansion cohort of patients with advanced mesothelioma or ovarian cancer.

TRIAL REGISTRATION NUMBER

NCT02955251.

Abstract 5672: Pharmacodynamics and potential predictive biomarkers of ABBV-428, a first-in-class mesothelin (MSLN)-CD40 bispecific, in patients with advanced solid tumors

Background: ABBV-428 is a first-in-class bispecific antibody against CD40 and MSLN designed to stimulate CD40 for tumor-specific immune activation with limited systemic toxicity (Cancer Immunol Res 2019;7:1864). In phase I findings, ABBV-428 was well tolerated up to 3.6mg/kg; 3/50 patients had long-term stable disease (SD; Luke et al. ESMO 2019). Here, pharmacodynamic and potential predictive biomarkers were assessed in the blood and tumor tissues in this phase I open-label, multicenter study (NCT02955251).

Methods: Patients ≥18 y had advanced solid tumors and progression/intolerance to standard therapies. ABBV-428 (≤3.6 mg/kg) was administered biweekly. CD40 receptor occupancy, absolute B cell counts, immune costimulatory activation markers, and serum cytokines were assessed at baseline and after treatment. MSLN expression (H-score) by IHC was reported at baseline. CD40/MSLN colocalization was assessed with a fluorescent multiplex assay. Paired tumor biopsy samples were collected at baseline and after treatment (C1D1, C2D1) to measure CD8+ T cells and PD-L1+ cells (IHC) and gene expression (NanoString Pancancer immune profiling panel). Immunologic constant of rejection (ICR) gene signature scores (J Immunother Cancer 2018;6:50) and IFNγ signatures (J Clin Invest 2017;127:2930) were used to characterize the tumor immune inflammatory microenvironment. BAP1 gene was sequenced (Sanger) in mesothelioma samples in 3 patients with long-term SD.

Results: In peripheral blood, there was >90% CD40 receptor occupancy starting at 0.8 mg/kg. There was a transient decrease in circulating B cells 2-24 hrs after administration of ABBV-428, followed by an increase in B cell costimulatory activation markers (CD80, CD86, CD69) across dose groups with no evidence of cytokine response (IFNγ, IL-10, IL-12p70, IL-6, IL-8, TNFα, IL-1β, IL-2). There was no consistent change in tumor-infiltrating CD8+ T cells or PD-L1+ cells after ABBV-428 treatment in paired tumor biopsy samples from 13 patients. Patients with SD had higher ICR scores and a higher IFNγ gene signature at baseline than those with progressive disease. There was no correlation between baseline MSLN expression level and clinical response. Wide intertumor variability of MSLN/CD40 colocalization was observed from 4 tumor biopsy samples. No well-established recurrent mutations were seen in BAP1, which are correlated with better prognosis in mesothelioma patients.

Conclusions: These data show that ABBV-428 binds and activates CD40 in the blood leading to B cell activation with no evidence of systemic cytokine production or significant change in the tumor immune microenvironment. Evidence of inflamed immune tumor microenvironment was observed at baseline from long-term SD patients. These results may explain the clinical observations from the current ABBV-428 clinical trial.

Citation Format: Hua Fang, Shiming Ye, Anita Reddy, Tolga Turan, Andrew Woolley, Debra T. Chao, Cyril Ramathal, William R. Henner, Kinjal Hew, Michael McDevitt, Joel Hayflick, Frances Fan, Kathryn Allaire, Lawrence Fong. Pharmacodynamics and potential predictive biomarkers of ABBV-428, a first-in-class mesothelin (MSLN)-CD40 bispecific, 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 5672.

A phase I study of CD40 agonist ABBV-927 plus OX40 agonist ABBV-368 with or without the PD-1 inhibitor budigalimab in patients with advanced solid tumors

TPS3147

Background: CD40 is a key costimulatory molecule for both the innate and adaptive immune systems that is essential for T-cell activation and proliferation. OX40 is a costimulatory molecule that is involved in enhancing nascent immune responses and concomitantly acts to suppress regulatory T-cell activity. ABBV-927 and ABBV-368 are potent agonistic antibodies against CD40 and OX40, respectively. This open-label, Phase 1 study will evaluate the doublet combination of ABBV-927 and ABBV-368 and the triplet combination of ABBV-927, ABBV-368, and the programmed cell death protein-1 (PD-1) inhibitor budigalimab in patients with advanced solid tumors. Methods: For this study (NCT03893955), patients must be ≥18 y with an Eastern Cooperative Oncology Group performance status of 0-1. Patients must have an advanced solid tumor that has progressed on standard therapies. Disease-specific cohorts will include patients with non-small cell lung cancer (NSCLC) and triple-negative breast cancer (TNBC). Patients with NSCLC must have previously received a PD-1/PD-ligand 1 inhibitor and a platinum-based therapy and no more than one prior immunotherapy. Patients with TNBC must not have received immunotherapy. Patients with uncontrolled central nervous system metastases will be excluded. The recommended Phase 2 dose (RP2D) will first be identified with ABBV-927 + ABBV-368 in patients with solid tumors (Arm A) and will be expanded in disease-specific cohorts including TNBC. The RP2D of ABBV-927 + ABBV-368 + budigalimab will be identified in patients with NSCLC (Arm B). The primary endpoints are determination of the RP2D of ABBV-927 + ABBV-368, the RP2D of ABBV-927 + ABBV-368 + budigalimab, and overall response rate; duration of response, progression-free survival, safety, and pharmacokinetics are secondary endpoints. Screening began on 21 May 2019, and enrollment is ongoing. Clinical trial information: NCT03893955 .

Abstract A030: Biomarker study of vantictumab plus paclitaxel in HER2- breast cancer patients

Introduction: We have developed a monoclonal antibody, vantictumab, that blocks canonical Wnt/β-catenin signaling through binding of five FZD receptors (1, 2, 5, 7, and 8). This antibody inhibits the growth of several tumor types, including breast. Vantictumab reduces tumor-initiating cell frequency and exhibits synergistic activity with standard-of-care (SOC) agents (Gurney et al., 2012). To confirm the mechanism of action and to potentially target breast cancer patients most likely to respond to vantictumab, we undertook a biomarker study. Methods: We previously identified a 6-gene Wnt pathway-related signature, FBXW2, CCND2, RHOU, CTBP2, WIF1, and DKK1, based on microarray gene expression data from 8 BC patient-derived xenograft (PDX) models with established in vivo response to vantictumab plus SOC. This signature successfully predicted the response of 8 additional and independent PDX breast tumors. We further developed a qPCR Research Use Only (RUO) assay for the 6 genes for use on FFPE human breast tumor samples. This assay was evaluated in the phase 1b study of vantictumab in combination with paclitaxel in locally recurrent or metastatic HER2- breast cancer (NCT01973309) and the signature was refined using a Lasso model with overall survival as the outcome. A repeated 10 fold cross-validation was used to evaluate the performance of the gene signature. The association of the signature with progression-free survival (PFS) and overall survival (OS) was examined (n=40 patients). Furthermore, pharmacodynamic (PD) biomarker analyses were performed on tumor biopsies and hair follicles by comparing gene expression data from post-treatment time points versus baseline data (Affymetrix U133 plus 2 Microarrays). Results: A potential predictive 6-gene Wnt pathway biomarker was identified based on preclinical data and the biomarker was evaluated and refined in a phase 1b study of vantictumab in combination with paclitaxel in HER2- breast cancer. In the phase 1b study, AUC = 75% with repeated 10 fold cross-validation measuring the performance of the gene signature. Based on this analysis, two genes, RHOU and DKK1, were dropped from the preclinical gene signature, which was consistent with the feature ranking in the preclinical qPCR data. The refined 4-gene signature was significantly associated with both PFS and OS at a 50% percentile cut-off. In addition, analysis of PD biomarkers demonstrated that Wnt pathway target genes including AXIN2, LEF1, and CTNNB1 were downregulated while differentiation markers, e.g., KRT19 and Wnt pathway inhibitors, e.g., SFRP1, DKK3 were upregulated by vantictumab plus paclitaxel. Conclusions: We developed a 4-gene signature as a potential predictive biomarker for the response to vantictumab plus paclitaxel in HER2- breast cancer. PD biomarker analysis in tumors and hair follicles confirmed the mechanism of action of vantictumab in patient samples. Preliminary efficacy of vantictumab plus paclitaxel in the phase 1b study was encouraging, particularly in breast cancer patients positive for the 4-gene signature. Updated biomarker and PK/PD data from the phase 1b trial (NCT01973309) will also be presented.

Citation Format: Chun Zhang, William R. Henner, Min Wang, Fiore Cattaruzza, Pete Yeung, Gilbert O'Young, Yuwang Liu, Gretchen Argast, Lu Xu, Shailaja Uttamsingh, John Lewicki, Ann M. Kapoun. Biomarker study of vantictumab plus paclitaxel in HER2- breast cancer patients [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A030.

Targeting Notch signaling with a Notch2/Notch3 antagonist (tarextumab) inhibits tumor growth and decreases tumor-initiating cell frequency

PURPOSE

The Notch pathway plays an important role in both stem cell biology and cancer. Dysregulation of Notch signaling has been reported in several human tumor types. In this report, we describe the development of an antibody, OMP-59R5 (tarextumab), which blocks both Notch2 and Notch3 signaling.

EXPERIMENTAL DESIGN

We utilized patient-derived xenograft tumors to evaluate antitumor effect of OMP-59R5. Immunohistochemistry, RNA microarray, real-time PCR, and in vivo serial transplantation assays were employed to investigate the mechanisms of action and pharmacodynamic readouts.

RESULTS

We found that anti-Notch2/3, either as a single agent or in combination with chemotherapeutic agents was efficacious in a broad spectrum of epithelial tumors, including breast, lung, ovarian, and pancreatic cancers. Notably, the sensitivity of anti-Notch2/3 in combination with gemcitabine in pancreatic tumors was associated with higher levels of Notch3 gene expression. The antitumor effect of anti-Notch2/3 in combination with gemcitabine plus nab-paclitaxel was greater than the combination effect with gemcitabine alone. OMP-59R5 inhibits both human and mouse Notch2 and Notch3 function and its antitumor activity was characterized by a dual mechanism of action in both tumor and stromal/vascular cells in xenograft experiments. In tumor cells, anti-Notch2/3 inhibited expression of Notch target genes and reduced tumor-initiating cell frequency. In the tumor stroma, OMP-59R5 consistently inhibited the expression of Notch3, HeyL, and Rgs5, characteristic of affecting pericyte function in tumor vasculature.

CONCLUSIONS

These findings indicate that blockade of Notch2/3 signaling with this cross-reactive antagonist antibody may be an effective strategy for treatment of a variety of tumor types.