Pertuzumab Plus Trastuzumab for Treatment-Refractory HER2-Amplified Metastatic Colorectal Cancer: Comparison of the MyPathway Trial With a Real-World External Control Arm.

PURPOSE: We compared overall survival (OS) in patients with human epidermal growth factor receptor 2 (HER2)-amplified, treatment-refractory metastatic colorectal cancer (mCRC) receiving pertuzumab plus trastuzumab (PER-HER) in the phase IIa MyPathway multibasket study (ClinicalTrials.gov identifier: NCT02091141) with OS in those receiving routine clinical care in an electronic health record-derived external control arm. METHODS: A noninterventional study was conducted using patient-level data from MyPathway participants receiving PER-HER and real-world patients with HER2-amplified treatment-refractory mCRC receiving routine clinical care. This study used a deidentified US-based clinico-genomic database (CGDB). For patients in the CGDB who met study eligibility criteria at multiple index dates (treatment initiation dates in the treatment-refractory setting), all eligible index dates were used for the analysis. Standardized mortality ratio weighting on the basis of propensity score derived a pseudopopulation (postweighting population) balancing key prognostic variables between arms. Multivariate Cox proportional hazards models were used for estimation of the hazard ratio (HR) in the primary OS analysis. A series of sensitivity analyses were conducted to investigate the robustness and consistency of the primary analysis. RESULTS: The PER-HER arm comprised 57 patients enrolled in the MyPathway study by August 1, 2017 (data cutoff); the external control arm comprised 18 patients (27 index dates) with HER2-amplified mCRC who met the major MyPathway eligibility criteria in CGDB collected between 2011 and 2019. The estimated HR for OS from the multivariate Cox proportional hazards model in the postweighting population was 0.729 (95% CI, 0.184 to 3.900). The results of sensitivity analyses were consistent with the primary analysis in terms of the point estimate of HR. CONCLUSION: Despite a small sample size, these findings suggest that PER-HER could have a potential OS benefit for this population.

Sialic acid is an essential moiety of mucin as a hydroxyl radical scavenger.

In this work, we examined the antioxidant role of mucin, a typical sialic acid containing high-molecular weight glycoprotein. The function of mucin as a hydroxyl radical (.OH) scavenger was characterized using bovine submaxillary gland mucin (BSM). Non-treated BSM effectively protected DNA from the attack of .OH; however, desialylated BSM lost this potential. Moreover, we estimated the scavenging effects of BSM against .OH generated by UV irradiation of hydrogen peroxide using ESR analysis. Our results indicate that BSM has .OH scavenging ability the and sialic acid in mucin is an essential moiety to scavenge .OH.

Formation of albumin dimers induced by exposure to peroxides in human plasma: a possible biomarker for oxidative stress.

Human serum albumin (HSA) has one free thiol residue at Cys-34 that is likely oxidized by various reactive oxygen species (ROS). We attempted to identify the oxidation product of Cys-34 of HSA following exposure of plasma to ROS. Oxidation induced by tert-butyl hydroperoxide (t-BuOOH) of this free cysteine residue in HSA was observed in detail. Analysis of oxidized albumin in a partially purified fraction obtained by affinity column chromatography clearly revealed the formation of albumin disulfide dimers following t-BuOOH exposure. Albumin disulfide dimer formation was observed in normal plasma following treatment with various peroxides, as well as in untreated plasma from patients on hemodialysis using SDS-PAGE and Western blot analysis. The present results indicate that albumin dimers are oxidative products derived from peroxides, and that their presence in plasma might be a marker of oxidative stress as secondary metabolites of peroxidation.