First-in-human phase Ib study of ATRC-101, an engineered version of a patient-derived antibody targeting a tumor-restricted ribonucleoprotein complex

TPS3168

Background: ATRC-101 is a fully human, engineered IgG1 version of an antibody discovered through a a target-agnostic screen to identify patient-derived antibodies that bind selectively to public tumor antigens. The parental antibody was identified from B cells in the active immune response of a patient receiving checkpoint therapy for Stage IV non-small cell lung cancer (NSCLC). A fluorescently conjugated version of ATRC-101 binds selectively to human tumor specimens including a majority of NSCLC, acral melanoma, breast, colorectal, and ovarian cancer samples. No reactivity of toxicological significance is found across a wide range of normal human tissues. ATRC-101 displays dose-dependent, single-agent activity in syngeneic mouse tumor models, including the EMT6 breast cancer model, which displays a T cell-excluded microenvironment often observed in human tumors, and in which checkpoint inhibitors targeting the PD-1 axis exhibit limited activity. Dosing with ATRC-101 in the EMT6 model causes marked changes in the tumor microenvironment, including a shift from the M2 to the M1 macrophage phenotype and infiltration of T cells. ATRC-101 does not appear to act via NK cell-driven ADCC; instead, activity in vivo is dependent both on Fc region interactions with Fc receptors, likely on myeloid rather than lymphoid cells, and on the presence of CD8+ T cells. ATRC-101 binds to a target that is a ribonucleoprotein (RNP) complex containing polyadenylate-binding protein 1 (PABP-1) bound to poly(A)RNA. Whereas both PABP-1 and poly(A)RNA are ubiquitously expressed at high levels in normal tissues and have been localized intracellularly, the ATRC-101 target is detected extracellularly on tumor cells grown in vivo. The basis for the tumor-selectivity of ATRC-101 as well as the extracellular localization of the target is under investigation. Ascending doses of ATRC-101 were well tolerated in multiple non-clinical safety studies. Methods: ATRC-101-A01 is an open-label, 3+3, Phase 1b safety study in patients with acral melanoma, NSCLC, breast, ovarian, and colorectal cancers. Participants are accruing in the first dose cohort. ATRC-101 is administered every 21 days up to 24 months or until disease progression. The primary objective of the trial is to determine the safety and tolerability of ATRC-101. Secondary objectives are to characterize the pharmacokinetic profiles of ATRC-101 and to assess antitumor activity as determined by RECIST 1.1 and lymphocytic infiltration in the tumor microenvironment. Clinical trial information: NCT04244552 .

Oxime derivatives related to AP18: Agonists and antagonists of the TRPA1 receptor

AP18 1 was recently disclosed as an antagonist of the TRPA1 receptor by the research group of Patapoutian. However, no detailed structure-activity relationships around 1 have been disclosed. Thus, a small number of oximes related to AP18 were examined in order to characterize the determinants of TRPA1 activity. Congeners of AP18 were found to possess both agonist and antagonist activity, suggesting that AP18 may behave as a covalent antagonist of the TRPA1 ion-channel.

The heart of the matter: Ottawa surgeons make history and create a controversy

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