Impact of drug-linker on method selection for analytical characterization and purification of antibody-drug conjugates.

In addition to traditional characterisation methods of hydrophobic interaction (HIC) and reverse phase (RP) chromatography, an anion exchange chromatography (AIEX) was developed to analyse and purify antibody drug conjugates (ADCs). Since different drug antibody ratio (DAR) species may impact biological activity, therapeutic index, PK parameters or even potential immunogenicity, homogenous ADC DAR demands have been significantly increasing. To accelerate linker designs, drug screening and ADC DAR purification for in vitro and in vivo studies, we built the analytical toolbox including HIC, RP, AIEX, icIEF, SEC, and MS for downstream ADC DAR purification using HIC and AIEX. The established analytical methods can quickly assess the quality of ADC DAR profiles and provide important information to select the proper ADC DAR purification method. Since drug-linker structures can significantly affect ADC physicochemical properties, and highly impact on selections of analytical methods, we applied both HIC and AIEX characterisation and purification platforms to achieve ADC DAR homogenous. Our experiments also implied that unlike HIC, AIEX could be used to separate DAR4 positional isomers.

Correlative Analysis of ATM, RB1, ERCC2, and FANCC Mutations and Pathologic Complete Response After Neoadjuvant Chemotherapy in Patients with Muscle-invasive Bladder Cancer: Results from the SWOG S1314 Trial.

We previously reported that tumors harboring any one of four gene mutations (ATM, RB1, FANCC, or ERCC2) were likely to respond to neoadjuvant cisplatin-based chemotherapy (NAC), resulting in cancer-free surgical specimens at the time of cystectomy (pT0). Here, we report our validation of this finding. Using the CARIS 592 Gene Panel (Caris Life Sciences, Phoenix, AZ, USA), we analyzed 105 pre-NAC tumor specimens from a large multicenter trial (S1314) of either neoadjuvant gemcitabine and cisplatin (GC), or dose-dense methotrexate, vinblastine, Adriamycin, and cisplatin (DDMVAC). We found that a mutation in any one of these four genes predicted for pT0 at surgery (odds ratio = 5.36; 95% confidence interval [CI] 2.05, 14.02; two-sided p = 0.0006). The biomarker was better at predicting the presence of disease (negative predictive value for pT0 86%; 95% CI 73%, 94%) than the absence of disease (positive predictive value for pT0 48%; 95% CI 35%, 62%). There was no evidence of an interaction between the treatment arm (DDMVAC vs GC) and the genetic variant in terms of pT0. When combined with clinical assessment, these findings help inform patient selection for bladder preservation after cisplatin-based chemotherapy. PATIENT SUMMARY: A common standard of care for patients with muscle-invasive bladder cancer is neoadjuvant chemotherapy (NAC) followed by cystectomy to achieve cure. We previously discovered that specific DNA mutations in tumor samples collected at initial biopsy (transurethral resection of a bladder tumor) were predictive of a complete response to NAC. In other words, patients with these mutations were more likely to have a bladder found to be cancer free after surgery. In this study, we analyzed a larger set of tumor samples from a national clinical trial of chemotherapy followed by cystectomy to validate these earlier findings. We conclude that this biomarker test, when combined with careful clinical assessment, can be used to allocate patients to careful bladder surveillance instead of surgery. This hypothesis has been tested in the RETAIN trial presented previously (NCT02710734).