Search

BackgroundATRC-101 is an engineered version of an immunoglobulin G1 antibody that was discovered in a patient with non-small cell lung cancer (NSCLC) experiencing stable disease while being treated with anti–programmed death-1 therapy. ATRC-101 targets a tumor-specific ribonucleoprotein complex containing polyadenylate binding protein-1, which has been found to be present in the majority of NSCLC, acral melanoma, breast, colorectal, and ovarian cancer samples tested. Target immunoreactivity and single-agent activity have been observed in mouse models. Preclinical data suggest that ATRC-101 stimulates both innate and adaptive immune activity against tumors.MethodsATRC-101-A01 is a phase 1b trial (3+3 dose escalation with expansion cohorts) in patients with solid tumors treated with ATRC-101 monotherapy every 2 or 3 weeks (Q2W or Q3W), or ATRC-101 in combination with pembrolizumab, until unacceptable toxicity or disease progression at doses of 0.3–30 mg/kg, pending dose-limiting toxicities. The primary objective is safety and secondary objectives are to characterize the pharmacokinetic profile, immunogenicity, and anti-tumor activity of ATRC-101, and to determine the recommended dose for expansion. Pharmacodynamic studies will also be performed to evaluate changes from baseline in specific immune cell populations and cytokine levels in blood and tumors. Results from the ATRC-101 0.3–30 mg/kg monotherapy Q3W cohorts are presented in this abstract (data cutoff: July 16, 2021).ResultsTwenty-four participants with solid tumors (13 colorectal, 5 ovarian, 3 breast, 2 NSCLC, 1 acral melanoma) aged 27–75 years with a median 5 lines of prior therapy were treated Q3W in five dose cohorts. No dose-limiting toxicities were observed. Eight participants (33%) experienced grade ≥3 treatment-emergent adverse events. The maximum serum concentration of ATRC-101 and treatment exposure appeared to be dose proportional. Stable disease was observed in eight patients and best response per RECIST v1.1 was associated with expression of the ATRC-101 target. Multiple biomarkers, such as treatment-associated changes in the composition of CD3+, CD4+, and CD8+ T cells in the blood, and serum cytokines/chemokines, including those predicted to activate antigen-presentation pathways, support the proposed mechanism of action of ATRC-101 and will be presented.ConclusionsThese first-in-human data suggest a manageable safety profile for ATRC-101 Q3W, with no dose-limiting toxicities observed. Pharmacokinetics appear to be dose proportional. Enrollment in the Q2W monotherapy dose-escalation cohort and at the 30 mg/kg dose level Q3W is continuing. Trial sites have been activated to test ATRC-101 in combination with pembrolizumab, and combination with chemotherapy is also planned.Trial RegistrationTrial Registration: NCT04244552Ethics ApprovalThis study was approved by the institutional review board or ethics committee as required for each participating site.

BackgroundB7-H6 is a member of the B7 family of immune receptors, which is expressed in several solid tumor types but very little expression can be detected in normal tissues.1 2 BI 765049 is a novel IgG-like bispecific T-cell engager designed to bind simultaneously to B7-H6 on tumor cells and CD3 on T cells, resulting in cytolytic synapse formation and tumor lysis. Preclinical studies have demonstrated that BI 765049 monotherapy induced dose-dependent anti-tumor activity in humanized in vivo CRC tumor models. Consistent with the mode of action, the treatment with BI 765049 led to target cell apoptosis, local T-cell activation/proliferation and cytokine production in the tumor tissue, with PD-(L)1 upregulation.3 Activation of the PD-(L)1 provides the rationale for combining BI 765049 with a PD1 inhibitor.MethodsNCT04752215 is a first-in-human, open-label, dose-escalation trial of BI 765049 ± the PD-1 inhibitor, ezabenlimab. Adults with advanced, unresectable and/or metastatic CRC, NSCLC, HNSCC, hepatocellular, gastric or pancreatic carcinoma are eligible. Patients must have failed on, or be ineligible, for standard therapies. B7-H6 positivity must be confirmed at screening by central review (immunohistochemistry assay) in archived tissues/in-study fresh biopsies (except CRC). Patients must have ≥1 evaluable lesion (modified RECIST 1.1) outside of the central nervous system and adequate organ function. The primary objective is to determine the maximum tolerated dose (MTD) or recommended dose for expansion of BI 765049 ± ezabenlimab, based on dose-limiting toxicities during the MTD evaluation period. Further objectives are to evaluate safety, tolerability, PK/PD and preliminary efficacy of BI 765049 ± ezabenlimab. The trial may assess up to 4 dosing regimens: A (BI 765049 once every 3 weeks [q3w]); B1 (BI 765049 qw); B2 (BI 765049 qw with step-in doses); C (BI 765049 + ezabenlimab [q3w]). Dose escalation will be guided by a Bayesian Logistic Regression Model with overdose control that will be fitted to binary toxicity outcomes using a hierarchical modelling approach to jointly model all dosing regimens. Treatment will be allowed to continue until confirmed progressive disease, unacceptable toxicity, other withdrawal criteria or for a maximum duration of 36 months, whichever occurs first. Approximately 150–175 patients will be screened and ~120 patients enrolled. As of July 2021, patients are being recruited in early dose-escalation cohorts.AcknowledgementsMedical writing support for the development of this abstract, under the direction of the authors, was provided by Becky O’Connor, of Ashfield MedComms, an Ashfield Health company, and funded by Boehringer Ingelheim.Trial RegistrationNCT04752215ReferencesBrandt et al. J Exp Med 2009;206:1495–503.Boehringer Ingelheim. Data on file.Hipp et al. AACR Annual Meeting 2021.Ethics ApprovalThe trial will be carried out in compliance with the protocol, the ethical principles laid down in the Declaration of Helsinki, in accordance with the ICH Harmonized Guideline for Good Clinical Practice (GCP) and the EU directive 2001/20/EC/EU regulation 536/2014.

Background VT1021, a cyclic pentapeptide, reprograms myeloid-derived suppressor cells (MDSCs) and induces the production of thrombospondin-1 (Tsp-1) in the tumor microenvironment (TME). Tsp-1, via binding to CD36 and CD47, induces apoptosis in tumor and endothelial cells, blocks the ‘do-not-eat-me’ signal, increases the M1:M2 macrophage ratio and activates cytotoxic T lymphocytes (CTLs). Preclinical studies showed robust anti-tumor activities of VT1021 in multiple animal models. Methods This is a first-in-human, Ph 1/2, open-label, multicenter dose escalation and expansion study in advanced solid tumors. The primary objectives are to determine the recommended Phase 2 dose (RP2D) and characterize the safety and tolerability of VT1021. Secondary objectives are to characterize the adverse event (AE) profile, evaluate pharmacokinetics (PK), and describe preliminary efficacy. Exploratory objectives include evaluation of pharmacodynamic effects of VT1021 in tumor, TME, and peripheral blood. The expansion phase focuses on ovarian, pancreatic, triple negative breast cancer, glioblastoma, and a basket cohort with high CD36-expressing tumors. Results In the escalation phase, 46 subjects received between 0.5–15.6 mg/kg of VT1021 by IV infusion twice weekly. VT1021 has been well tolerated through all doses tested. One patient dosed at 1.0 mg/kg developed a grade 3 infusion reaction and 3 patients dosed at 1.0, 6.6, and 8.8 mg/kg respectively developed grade 2 infusion reactions. Other drug related AEs included grade 1–2 fatigue (n=7), nausea (n=4), constipation (n=2), increased aspartate aminotransferase (n=2) and blood bilirubin (n=2), hypomagnesaemia (n=2), and dizziness (n=2). Dose proportionality was observed in PK analysis. Among 28 evaluable subjects, one partial response (thymoma, 372+ days on treatment) and 11 stable disease (SD) in 9 different solid tumors have been observed for a disease control rate of 43%. Seven of eleven SDs had high CD36 AND high CD47 expression with an average duration of 162 days on study. VT1021 induced Tsp-1 production in peripheral blood cells at most dose levels. In addition, on-study biopsies exhibited increased Tsp-1 expression in the TME by activation of p53 in MDSCs, increased CTL infiltration, increased M1:M2 macrophage ratio, and reduced regulatory T cells in the TME. The RP2D was declared to be 11.8 mg/kg and enrollment in tumor-specific expansions is on-going. Conclusions Through all doses tested, VT1021 was safe and well tolerated, with dose proportional PK properties. In addition, VT1021 has demonstrated activities in reprogramming the TME which resulted in a high disease control rate in subjects with tumors expressing both high CD36 and high CD47. Trial Registration NCT03364400 Ethics Approval The study was approved by Northwestern University Medical School institutional review board (IRB), approval number 00000418, Horizon Oncology Center IRB, approval number 00001313, South Texas Accelerated Research Therapeutic IRB, approval number 00003657, University of Oklahoma Health Sciences Center IRB, approval number 00006075, Cleveland Clinic IRB, approval number 00000536, Florida Cancer Specialists IRB, approval number 00006075, Case Western IRB, approval number 00000536, Beth Israel Deaconess Hospital and Dana Farber Cancer Institute IRB, approval number 00000753 and MD Anderson IRB, approval number 00006023.

Endoglin is an endothelial cell membrane receptor essential for angiogenesis and highly expressed on the vasculature of many tumor types, including hepatocellular carcinoma (HCC). TRC105 is a chimeric IgG1 anti-CD105 monoclonal antibody that inhibits angiogenesis and tumor growth by endothelial cell growth inhibition, ADCC and apoptosis, and complements VEGF inhibitors.The aim of this phase II study was to evaluate the efficacy of anti-endoglin therapy with TRC105 in patients with advanced HCC, post-sorafenib.Patients with HCC and compensated liver function (Childs-Pugh A/B7), ECOG 0/1, were enrolled to a single-arm, phase II study of TRC105 15 mg/kg IV every two weeks. Patients must have progressed on or been intolerant of prior sorafenib. A Simon optimal two-stage design was employed with a 50% four-month PFS target for progression to the second stage. Correlative biomarkers evaluated included DCE-MRI as well as plasma levels of angiogenic biomarkers and soluble CD105.A total accrual of 27 patients was planned. However, because of lack of efficacy and in accordance with the Simon two-stage design, 11 patients were enrolled. There were no grade 3/4 treatment-related toxicities. Most frequent toxicities were headache (G2; N = 3) and epistaxis (G1; N = 4). One patient had a confirmed partial response by standard RECIST criteria and biologic response on DCE-MRI but the four-month PFS was insufficient to proceed to the second stage of the study.TRC105 was well tolerated in this HCC population following sorafenib. Although there was evidence of clinical activity, this did not meet prespecified criteria to proceed to the second stage. TRC105 development in HCC continues as combination therapy with sorafenib.

Meeting abstracts Tremelimumab is a fully human monoclonal antibody that binds to CTLA-4 expressed on the surface of activated T lymphocytes and results in inhibition of B7-CTLA-4-mediated down regulation of T cell activation. Both transcatheter arterial chemoembolization (TACE) and radiofrequency