Higher-order death receptor 5 (DR5) clustering can induce tumor cell death; however, therapeutic compounds targeting DR5 have achieved limited clinical efficacy. We describe HexaBody-DR5/DR5, an... Show moreHigher-order death receptor 5 (DR5) clustering can induce tumor cell death; however, therapeutic compounds targeting DR5 have achieved limited clinical efficacy. We describe HexaBody-DR5/DR5, an equimolar mixture of two DR5-specific IgG1 antibodies with an Fc-domain mutation that augments antibody hexamerization after cell surface target binding. The two antibodies do not compete for binding to DR5 as demonstrated using binding competition studies, and binding to distinct epitopes in the DR5 extracellular domain was confirmed by crystallography. The unique combination of dual epitope targeting and increased IgG hexamerization resulted in potent DR5 agonist activity by inducing efficient DR5 outside-in signaling and caspase-mediated cell death. Preclinical studies in vitro and in vivo demonstrated that maximal DR5 agonist activity could be achieved independent of Fc gamma receptor-mediated antibody crosslinking. Most optimal agonism was observed in the presence of complement complex C1, although without inducing complement-dependent cytotoxicity. It is hypothesized that C1 may stabilize IgG hexamers that are formed after binding of HexaBody-DR5/DR5 to DR5 on the plasma membrane, thereby strengthening DR5 clustering and subsequent outside-in signaling. We observed potent antitumor activity in vitro and in vivo in large panels of patient-derived xenograft models representing various solid cancers. The results of our preclinical studies provided the basis for an ongoing clinical trial exploring the activity of HexaBody-DR5/DR5 (GEN1029) in patients with malignant solid tumors. Show less
Familial Adult Myoclonic Epilepsy (FAME) is a genetically heterogeneous disorder characterized by cortical tremor and seizures. Intronic TTTTA/TTTCA repeat expansions in SAMD12 (FAME1) are the main... Show moreFamilial Adult Myoclonic Epilepsy (FAME) is a genetically heterogeneous disorder characterized by cortical tremor and seizures. Intronic TTTTA/TTTCA repeat expansions in SAMD12 (FAME1) are the main cause of FAME in Asia. Using genome sequencing and repeat-primed PCR, we identify another site of this repeat expansion, in MARCH6 (FAME3) in four European families. Analysis of single DNA molecules with nanopore sequencing and molecular combing show that expansions range from 3.3 to 14 kb on average. However, we observe considerable variability in expansion length and structure, supporting the existence of multiple expansion configurations in blood cells and fibroblasts of the same individual. Moreover, the largest expansions are associated with micro-rearrangements occurring near the expansion in 20% of cells. This study provides further evidence that FAME is caused by intronic TTTTA/TTTCA expansions in distinct genes and reveals that expansions exhibit an unexpectedly high somatic instability that can ultimately result in genomic rearrangements. Show less
Familial Adult Myoclonic Epilepsy (FAME) is characterised by cortical myoclonic tremor usually from the second decade of life and overt myoclonic or generalised tonic-clonic seizures. Four... Show moreFamilial Adult Myoclonic Epilepsy (FAME) is characterised by cortical myoclonic tremor usually from the second decade of life and overt myoclonic or generalised tonic-clonic seizures. Four independent loci have been implicated in FAME on chromosomes (chr) 2, 3, 5 and 8. Using whole genome sequencing and repeat primed PCR, we provide evidence that chr2-linked FAME (FAME2) is caused by an expansion of an ATTTC pentamer within the first intron of STARD7. The ATTTC expansions segregate in 158/158 individuals typically affected by FAME from 22 pedigrees including 16 previously reported families recruited worldwide. RNA sequencing from patient derived fibroblasts shows no accumulation of the AUUUU or AUUUC repeat sequences and STARD7 gene expression is not affected. These data, in combination with other genes bearing similar mutations that have been implicated in FAME, suggest ATTTC expansions may cause this disorder, irrespective of the genomic locus involved. Show less
Beurskens, F.; Overdijk, M.; Strumane, K.; Buijssel, A.O.; Vermot-Desroches, C.; Kroes, T.; ... ; Breij, E. 2018
