Evaluation of atezolizumab immunogenicity: Efficacy and safety (Part 2).

Antibody therapeutics can be associated with unwanted immune responses resulting in the development of anti-drug antibodies (ADA). Optimal methods to evaluate the potential effects of ADA on clinical outcomes in oncology are not well established. In this study, we assessed efficacy and safety, based on ADA status, in patients from over 10 clinical trials that evaluated the immune checkpoint inhibitor atezolizumab as a single agent or as combination therapy for several types of advanced cancers. ADA can only be observed post randomization, and imbalances in baseline prognostic factors can confound the interpretation of ADA impact. We applied methodology to account for the confounding effects of baseline clinical characteristics and survivorship bias on efficacy. Adjusted meta-analyses revealed that despite numerical differences in overall survival and progression-free survival between ADA-positive and ADA-negative patients from some studies, ADA-positive patients from studies with an overall treatment effect derived benefit from atezolizumab, compared with their adjusted controls. Based on large, pooled populations from atezolizumab monotherapy or combination studies, unadjusted descriptive analyses did not identify a clear relationship between ADA status and frequency or severity of adverse events. Data also suggested that any ADA impact is not driven by neutralizing activity. Collectively, this exploratory analysis suggests that the potential for ADA development should not impact treatment decisions with atezolizumab.

Effects of RG7652, a Monoclonal Antibody Against PCSK9, on LDL-C, LDL-C Subfractions, and Inflammatory Biomarkers in Patients at High Risk of or With Established Coronary Heart Disease (from the Phase 2 EQUATOR Study).

RG7652 (MPSK3169A), a fully human immunoglobulin G1 (IgG1) monoclonal antibody directed against proprotein convertase subtilisin/kexin type 9 (PCSK9), blocks the interaction between PCSK9 and low-density lipoprotein (LDL) receptor. EQUATOR (ClinicalTrials.govNCT01609140), a randomized, double-blind, and dose-ranging phase 2 study, evaluated RG7652 in patients (1) at high risk for or (2) with coronary heart disease (CHD). The primary end point was change in LDL cholesterol (LDL-C) from baseline to day 169. Patients (n = 248; median age, 64 years; 57% men; 52% with established CHD; 82% on statins) with baseline LDL-C levels of 90 to 250 mg/dl (mean, 126 mg/dl) continuing on standard-of-care therapy were randomized to receive 1 of 5 RG7652 doses or placebo, subcutaneously every 4, 8, or 12 weeks for 24 weeks. Significant dose-dependent reductions in LDL-C levels from baseline to nadir (56 to 74 mg/dl [48% to 60%]) were observed in all RG7652-dosed patients; effects persisted to day 169 with the highest doses (reduction vs placebo up to 62 mg/dl [51%]) with no unexpected safety signals. RG7652 reduced apolipoprotein B and lipoprotein(a) levels. LDL-C subfraction analysis by nuclear magnetic resonance spectroscopy revealed a prominent decrease in large LDL-C and some decrease in small LDL particles. There was significant reduction in mean particle size of LDL-C on day 169 but no significant reductions in systemic markers of inflammation (high-sensitivity C-reactive protein, interleukin-6, and tumor necrosis factor-alpha). RG7652 reduced LDL-C levels and was well tolerated in patients at high risk for or with CHD on standard-of-care therapy. In conclusion, RG7562 treatment affected large LDL-C and, to a lesser extent, small LDL-C particles; RG7562 did not affect systemic circulating pro-inflammatory cytokines or high-sensitivity C-reactive protein.