A phase Ia/IIa trial of Sym015, a MET antibody mixture, in patients with advanced solid tumours

Background MET gene amplification/mutation is implicated in oncogenesis of many tumor types. Sym015 is a recombinant antibody (Ab) mixture containing 2 humanized Abs binding non-overlapping epitopes on MET which has superior preclinical activity compared to other MET Abs. Here we present interim results from the First in Human study of Sym015. Methods In part 1 dose escalation, Sym015 was evaluated on every 2-week (q2w) schedule at 6/12/18/24 mg/kg doses in late line advanced solid tumor patients (pts). Based on PK/PD assessment, 18 mg/kg loading dose followed by 12 mg/kg q2w was selected as RP2D. The on-going Part 2 Dose expansion enrolls pts with MET amplification (METAmp >5 MET copies by Next Generation Sequencing (NGS) or FISH MET/CEP7 ratio >2.2 updated to ≥ 3.0) and/or MET exon 14 deletion (METEx14Δ) positive tumors. Central FISH confirmation of tumor MET status and longitudinal circulating tumor (ct)DNA profiling is performed. Results By April 2019, 51 pts (median age 61 yrs) have been treated, 12 pts in Part 1 and 39 pts in Part 2, the majority are non small cell lung cancer (NSCLC; 14 pts; 6 METAmp,7 METEx14Δ, 1 both) and gastric cancer (GC; 12 METAmp pts). Treatment-related adverse events (TRAE) occurred overall in 41,2%; TRAE ≥ gr3 in 9,8% (edema, colitis, septic shock, hypoalbuminemia, hypophosphatemia, increased amylase). No pts discontinued or died due to TRAE. The most common TRAE of ≥ 5% were fatigue 15.7%, peripheral edema 7,8%, nausea, decreased appetite, pruritus and abdominal pain reported by 5.9% of pts each. The table shows preliminary efficacy in NSCLC patients. Sym015 PK was slightly non-linear, with a dose-dependent t½ of 7-10 days for the first dose. 83% METAmp concordance (10/12 samples) between tumor and blood was observed. Table . 1490PD NSCLC Pt MET Status (Local Assessment) Best Response (Best % Change From Baseline) Previous MET TKI therapy Duration of Response (weeks) 1 METAmp NGS 6.8 Copies PR (-53%) No 80 2 METAmp NGS >5 Copies SD (-29%) No 9, Ongoing 3 METAmp NGS >5 Copies SD (+3%) No 9, Ongoing 4 METEx14Δ SD (-28%) No 7, Ongoing 5 METAmp FISH MET/ CEP7:4.9 SD (+6%) No 11 6 METEx14Δ SD (-4%) Yes 8 7 METEx14Δ SD (-21%) Yes 15 8 METEx14Δ SD (-20%) Yes 8 9 METAmp SISH MET/ CEP7: 15.2 Pending No Ongoing 10 METEx14Δ Pending Yes Ongoing 11 METEx14Δ + METAmp Pending Pending Ongoing 12 METEx14Δ Pending No Ongoing 13 METEx14Δ Pending No Ongoing 14 METEx14Δ Not Evaluable Yes Not Evaluable Conclusions Sym015 was well tolerated with early evidence of antitumor activity. Predictive biomarker analysis is underway. The study continues to enroll NSCLC patients with METAmp and/or METEx14Δ. MET screening in blood seems feasible and may be included in future trials. Clinical trial identification NCT02648724. Legal entity responsible for the study Symphogen A/S. Funding Symphogen A/S. Disclosure D.R. Camidge: Advisory / Consultancy: 2019: Takeda, CBT Pharmaceuticals, Daiichi-Sankyo (ILD adjudication committee), G1 Therapeutics (DSMB), Bio-Thera (DSMB), Blueprint; Advisory / Consultancy: 2018: AstraZeneca, Takeda, Arrys/Kyn, Regeneron, Hengrui, G1 Therapeutics (DSMB), Daiichi Sankyo (ILD adjudication committee), Hansoh (SRC), Bio-Thera (DSMB), Ribon, BMS, Blueprint, Roche/Genentech, Inivata; Advisory / Consultancy: 2017: Genoptix, G1 Therapeutics (DSMB), Mersana Therapeutics, Roche/Genentech, Takeda, Ignyta, Daiichi Sankyo (ILD adjudication committee), Hansoh SRC, Bio-Thera DSMB, Lycera, Revolution Med; Research grant / Funding (self), Research grant / Funding (institution): 2017: Takeda Investigator-initiated Trial; Research grant / Funding (self), Research grant / Funding (institution), Company Sponsored Trials at Institution: 2018/9: AbbVie, AstraZeneca, BMS, Hansoh, Lycera, MedImmune, Merck, Pfizer, Phosplatin, Roche/Genentech, Seattle Genetics, Symphogen, Takeda. F. Janku: Research grant / Funding (self): Novartis, Genentech, BioMed Valley Discoveries, Astellas, Agios, Plexxikon, Deciphera, Piqur, Symphogen, Bristol-Myers Squibb, Asana, Upsher-Smith Laboratories; Advisory / Consultancy: Guardant Health, IFM Therapeutics, Synlogic, Deciphera; Advisory / Consultancy, Shareholder / Stockholder / Stock options: Trovagene; Advisory / Consultancy: Immunomet. D.V. Catenacci: Honoraria (self), Advisory / Consultancy: Merck, BMS, Lilly, Astellas, Gritstone, Taiho, Five Prime, Genentech Roche, Foundation Medicine, Guardant Health, Tempus. H.C. Chung: Honoraria (self): Merck-Serono, Lilly, Foundation Medicine; Advisory / Consultancy: Taiho, Celltrion, MSD, Lilly,Quintiles, BMS, Merck-Serono; Research grant / Funding (institution): Lilly, GSK, MSD, Merck-Serono, BMS-ONO, Taiho. A. Dowlati: Advisory / Consultancy: Seattle genetics, Takeda, AbbVie; Research grant / Funding (institution): Takeda, Taiho, Roche, EMD Serono, Bayer, Tesaro, Regeneron, Amgen, Mirati, BMS. K.S. Rohrberg: Research grant / Funding (institution), Travel / Accommodation / Expenses: Roche; Research grant / Funding (institution): Loxo Oncology, Orion Pharma, Pfizer, PUMA, Cantargia, Genmab, Novartis, Incyte, Bayer, AstraZeneca, Alligator, Merck, BMS; Travel / Accommodation / Expenses: Sanofi; Research grant / Funding (institution): Symphogen. T.T. Poulsen: Full / Part-time employment: Symphogen A/S. H. Rudbaek: Full / Part-time employment: Symphogen A/S. L. Alifrangis: Full / Part-time employment: Symphogen A/S. R.P. Dalal: Full / Part-time employment: Symphogen A/S. All other authors have declared no conflicts of interest.