Intracellular Released Payload Influences Potency and Bystander-Killing Effects of Antibody-Drug Conjugates in Preclinical Models
Authors: Li, Fu; Emmerton, Kim K.; Jonas, Mechthild; Zhang, Xinqun; Miyamoto, Jamie B.; Setter, Jocelyn R.; Nicholas, Nicole D.; Okeley, Nicole M.; Lyon, Robert P.; Benjamin, Dennis R.; Law, Che-Leung
Antibody-drug conjugates (ADC) comprise targeting antibodies armed with potent small-molecule payloads. ADCs demonstrate specific cell killing in clinic, but the basis of their antitumor activity is not fully understood. In this study, we investigated the degree to which payload release predicts ADC activity in vitro and in vivo. ADCs were generated to target different receptors on the anaplastic large cell lymphoma line L-82, but delivered the same cytotoxic payload (monomethyl auristatin E, MMAE), and we found that the intracellular concentration of released MMAE correlated with in vitro ADC-mediated cytotoxicity independent of target expression or drug: antibody ratios. Intratumoral MMAE concentrations consistently correlated with the extent of tumor growth inhibition in tumor xenograft models. In addition, we developed a robust admixed tumor model consisting of CD30(+) and CD30(-) cancer cells to study how heterogeneity of target antigen expression, a phenomenon often observed in cancer specimens, affects the treatment response. CD30-targeting ADC delivering membrane permeable MMAE or pyrrolobenzodiazepine dimers demonstrated potent bystander killing of neighboring CD30(-) cells. In contrast, a less membrane permeable payload, MMAF, failed to mediate bystander killing in vivo, suggesting local diffusion and distribution of released payloads represents a potential mechanism of ADC-mediated bystander killing. Collectively, our findings establish that the biophysical properties and amount of released payloads are chief factors determining the overall ADC potency and bystander killing. (C) 2016 AACR.
Bi-allelic Mutations in TTC29 Cause Male Subfertility with Asthenoteratospermia in Humans and Mice
AMERICAN JOURNAL OF HUMAN GENETICS
Authors: Liu, Chunyu; He, Xiaojin; Liu, Wangjie; Yang, Shenmin; Wang, Lingbo; Li, Weiyu; Wu, Huan; Tang, Shuyan; Ni, Xiaoqing; Wang, Jiaxiong; Gao, Yang; Tian, Shixiong; Zhang, Lin; Cong, Jiangshan; Zhang, Zhihua; Tan, Qing; Zhang, Jingjing; Li, Hong; Zhong, Yading; Lv, Mingrong; Li, Jinsong; Jin, Li; Cao, Yunxia; Zhang, Feng
As a type of severe asthenoteratospermia, multiple morphological abnormalities of the flagella (MMAF) are characterized by the presence of immotile spermatozoa with severe flagellar malformations. MMAF is a genetically heterogeneous disorder, and the known MMAF-associated genes can only account for approximately 60% of human MMAF cases. Here we conducted whole-exome sequencing and identified bi-allelic truncating mutations of the TTC29 (tetratricopeptide repeat domain 29) gene in three (3.8%) unrelated cases from a cohort of 80 MMAF-affected Han Chinese men. TTC29 is preferentially expressed in the testis, and TTC29 protein contains the tetratricopeptide repeat domains that play an important role in cilia- and flagella-associated functions. All of the men harboring TTC29 mutations presented a typical MMAF phenotype and dramatic disorganization in axonemal and/or other peri-axonemal structures. Immunofluorescence assays of spermatozoa from men harboring TTC29 mutations showed deficiency of TTC29 and remarkably reduced staining of intraflagellar-transport-complex-B-associated proteins (TTC30A and IFT52). We also generated a TtC29-mutated mouse model through the use of CRISPR-Cas9 technology. Remarkably, TtC29-mutated male mice also presented reduced sperm motility, abnormal flagellar ultrastructure, and male subfertility. Furthermore, intracytoplasmic sperm injections performed for TtC29-mutated mice and men harboring TTC29 mutations consistently acquired satisfactory outcomes. Collectively, our experimental observations in humans and mice suggest that bi-allelic mutations in TTC29, as an important genetic pathogeny, can induce MMAF-related asthenoteratospermia. Our study also provided effective guidance for clinical diagnosis and assisted reproduction treatments.