A novel non-agonist c-Met antibody drug conjugate with superior potency over a c-Met tyrosine kinase inhibitor in c-Met amplified and non-amplified cancers
CANCER BIOLOGY & THERAPY
Authors: Fujita, Ryo; Blot, Vincent; Wong, Eley; Stewart, Christine; Lieuw, Vincent; Richardson, Robyn; Banah, Ammar; Villicana, Jose; Timmer, Anjuli; Coronella, Julia; Newman, Roland; Gymnopoulos, Marco
c-Met is a well-characterized oncogene that is associated with poor prognosis in many solid tumor types. While responses to c-Met inhibitors have been observed in clinical trials, activity appears to be limited to those with MET gene amplifications or mutations. We developed a c-Met targeted antibody-drug conjugate (ADC) with preclinical activity in the absence of MET gene amplification or mutation, and activity even in the context of moderate protein expression. The ADC utilized a high-affinity c-Met antibody (P3D12), that induced c-Met degradation with minimal activation of c-Met signaling, or mitogenic effect. P3D12 was conjugated to the tubulin inhibitor toxin MMAF via a cleavable linker (vc-MMAF). P3D12-vc-MMAF demonstrated potent in vitro activity in c-Met protein-expressing cell lines regardless of MET gene amplification or mutation status, and retained activity in cell lines with medium-low c-Met protein expression. In contrast, the c-Met tyrosine kinase inhibitor (TKI) PHA-665752 slowed tumor cell growth in vitro only in the context of MET gene amplification or very high protein expression. This differential activity was even more marked in vivo. P3D12-vc-MMAF demonstrated robust inhibition of tumor growth in the MET gene amplified MKN-45 xenograft model, and similar results in H1975, which expresses moderate levels of wild type c-Met without genomic amplification. By comparison, the c-Met TKI, PHA-665752, demonstrated modest tumor growth inhibition in MKN-45, and no inhibition at all in H1975. Taken together, these data suggest that P3D12-vc-MMAF may have a superior clinical profile in treating c-Met positive malignancies in contrast to c-Met pathway inhibitors.
Whole-exome sequencing of familial cases of multiple morphological abnormalities of the sperm flagella (MMAF) reveals new DNAHI mutations
Authors: Amiri-Yekta, Amir; Coutton, Charles; Kherraf, Zine-Eddine; Karaouzene, Thomas; Le Tanno, Pauline; Sanati, Mohammad Hossein; Sabbaghian, Marjan; Almadani, Navid; Gilani, Mohammad Ali Sadighi; Hosseini, Seyedeh Hanieh; Bahrami, Salahadin; Daneshipour, Abbas; Bini, Maurizio; Arnoult, Christophe; Colombo, Roberto; Gourabi, Hamid; Ray, Pierre F.
STUDY QUESTION: Can whole-exome sequencing (WES) of patients with multiple morphological abnormalities of the sperm flagella (MMAF) identify causal mutations in new genes or mutations in the previously identified dynein axonemal heavy chain 1 (DNAHI) gene? SUMMARY ANSWER: WES for six families with men affected by MMAF syndrome allowed the identification of DNAHI mutations in four affected men distributed in two out of the six families but no new candidate genes were identified. WHAT IS KNOWN ALREADY: Mutations in DNAHI, an axonemal inner dynein arm heavy chain gene, have been shown to be responsible for male infertility due to a characteristic form of asthenozoospermia called MMAF, defined by the presence in the ejaculate of spermatozoa with a mosaic of flagellar abnormalities including absent, coiled, bent, angulated, irregular and short flagella. STUDY DESIGN, SIZE, DURATION: This was a retrospective genetics study of patients presenting a MMAF phenotype. Patients were recruited in Iran and Italy between 2008 and 2015. PARTICIPANTS/MATERIALS, SETTING, METHODS: WES was performed for a total of 10 subjects. All identified variants were confirmed by Sanger sequencing. Two additional affected family members were analyzed by direct Sanger sequencing. To establish the prevalence of the DNAHI mutation identified in an Iranian family, we carried out targeted sequencing on 38 additional MMAF patients of the same geographical origin. RT-PCR and immunochemistry were performed on sperm samples to assess the effect of the identified mutation on RNA and protein. MAIN RESULTS AND THE ROLE OF CHANCE: WES in six families identified a causal mutations in two families. Two additional affected family members were confirmed to hold the same homozygous mutation as their sibling. In total, DNAHI mutations were identified in 5 out of 12 analyzed subjects (41.7%). If we only include index cases, we detected two mutated subjects out of six (33%) tested MMAF individuals. Furthermore we sequenced one DNAHI exon found to be mutated (c.8626-1G > A) in an Iranian family in an additional 38 MMAF patients from Iran. One of these patients carried the variant confirming that this variant is relatively frequent in the Iranian population. The effect of the c.8626-1G > A variant was confirmed by RT-PCR and immunochemistry as no RNA or protein could be observed in sperm from the affected men. LARGE SCALE DATA: N/A. LIMITATIONS, REASONS FOR CAUTION: WES allows the amplification of 80-90% of all coding exons. It is possible that some DNAHI exons may not have been sequenced and that we may have missed some additional mutations. Also, WES cannot identify deep intronic mutations and it is not efficient for detection of large genomic events (deletions, insertions, inversions). We did not identify any causal mutations in DNAHI or in other candidate genes in four out of the six tested families. This indicates that the technique and/or the analysis of our data can be improved to increase the diagnosis efficiency. WIDER IMPLICATIONS OF THE FINDINGS: Our findings confirm that DNAHI is one of the main genes involved in MMAF syndrome. It is a large gene with 78 exons making it challenging and expensive to sequence using the traditional Sanger sequencing methods. We show that WES sequencing is good alternative to Sanger sequencing to reach a genetic diagnosis in patients with severe male infertility phenotypes.