P - 161: A PHASE I DOSE - ESCALATION STUDY TO ASSESS THE ONCOLYTIC VIRUS VCN - 01 SAFETY AND EFFICACY IN REFRACTORY RETINOBLASTOMA PATIENTS Jaume Catal - Mora1,*, Jaume Mora 1,2 , Margarida Simao 1 , Francis Munier 3 , L

P - 161: A PHASE I DOSE - ESCALATION STUDY TO ASSESS THE ONCOLYTIC VIRUS VCN - 01 SAFETY AND EFFICACY IN REFRACTORY RETINOBLASTOMA PATIENTS Jaume Catal - Mora1,*, Jaume Mora 1,2 , Margarida Simao 1 , Francis Munier 3 , Livia Romero 4 , Ligia Fu 5 , Jesus Ardila 6 , Ida Russo 7 , Karina Senyase Zamarripa 8 , Jes s D az - Cascajosa 1 , Eduard Pedemonte - Sarrias 1 , Marina Barraso - Rodrigo 1 , Itziar Alonso Colmenero 1 , Dolors Molies - Navarrete 1 , Ana Mato - Berciano 9 , Carmen Blasco 9 , Manel Cascallo 9 , Guillermo L. Chantada 10 , ngel Montero - Carcaboso 10 1 Hospital Sant Joan de D u, Barcelona, Esplugues de Llobregat, Barcelona, Spain; 2 Pediatric Cancer Center Barcelona, Hospital Sant Joan de D u, Barcelona, Spain; 3 Hopital Ophtalmique Jules Gonin, Lausanne, Switzerland; 4 Unidad Oncolog a Ocular Instituto Oncol gico Dr. Luis Razetti, Caracas, Venezuela; 5 Hospital Escuela Universitario, Tegucigalpa, Honduras; 6 Centro M dico Imbanaco, Cali, Colombia; 7 Ospedale Pediatrico Bambino Ges , Roma, Italy; 8 HONU Childcare, Leon, Guanjuato, Mexico; 9 Theriva Biologics, Parets del Vall s, Barcelona, Spain; 10 Fundaci Sant Joan de D u, Espplugues de Llobregat, Barcelona, Spain. Patients (from 1 year to under 12 years of age) with intraocular retinoblastoma who failed conservative therapy facing imminent enucleation were eligible for this phase I, dose - escalation study (NCT 03284268 ) with two dose levels of VCN - 01 intravitreal injection ( 2 E+ 9 vp/eye per dose for the first patient) and 2 E+ 10 vp/eye dose in two doses on day 1 and 15 for the remaining 8 patients . The primary objective was to determine the safety and tolerability of intravitreal injections of VCN - 01 through assessment of adverse events and laboratory tests to establish the maximum tolerated dose (MTD) of VCN - 01 virus . Dose limiting toxicity (DLT) was defined as grade IV ocular toxicity or grade III systemic toxicity according to CTCAEv 04 . Response assessed by RB - RECIST criteria and toxicity were evaluated at day 42 of the first injection . Additionally, different biological samples were obtained to evaluate the excretion profile of VCN - 01 and to assess immune response by the presence of neutralizing antibodies in patients . Trial Design & Methods Retinoblastoma is the most frequent intraocular malignancy in children . Novel treatments must address three main needs : tumor selectivity to maximize anticancer action, reduced toxicity in healthy eye tissues, and reduced exposure to chemotherapy to minimize the risk of subsequent malignant neoplasms . Zabilugene almadenorepvec (VCN - 01 ) 1 is an oncolytic adenovirus targeting the E 2 F pathway and expressing hyaluronidase that is currently being tested in several indications : Preclinical work demonstrated antitumor activity for retinoblastoma in patient derived retinoblastoma models 2 . Additionally, evidences for VCN - 01 tumor selectivity were collected, with absence of replication in normal retinas in rabbit . We report here a first - in - children study aiming to assess its safety profile and initial efficacy . Background Results/Graphs/Data *Address correspondence to : Jaume Catal Mora (jaume . catala@sjd . es) References 1. Rodr guez - Garc a A et al. (2015) Safety and efficacy of VCN - 01, an oncolytic adenovirus combining fiber HSG - binding domain replacement with RGD and hyaluronidase expression. Clin Cancer Res 21:1406 - 18 2. Pascual Pasto G et al. (2019) Therapeutic targeting of the RB1 pathway in retinoblastoma with the oncolytic adenovirus VCN - 01. Sci Transl Med 11:eaat9321 D1 D15 D28 D45 D180 MRI - MDD Oft - ERG Safety visit 6 months Follow - up VCN - 01 Oft - Lab ERG VCN - 01 MRI - MDD Oft - ERG Demographics High dose Low dose 2E+10 vp/eye (n=8) 2E +9 vp/eye (n=1) 3.2 2 Median Age, years (2 - 7) NA Range 5/3 0/1 Sex (Male / Female) 16.35 12 Median Weight, Kg (9,4 - 31.0) NA Range 103.5 98 Median Height, cm (87 - 126) NA Range 3 1 Somatic Type of mutation RB1 gene 5 NA Germinal 5 NA With active tumor in ONLY one eye, and the contralateral eye already enucleated If germinal 0 0 A Group IIRC Classification for Intraocular retinoblastoma (International Intraocular Retinoblastoma Classification) 1 0 B Group 2 0 C Group 5 1 D Group 0 0 E Group Previous treatments Vitreous seeds Subretinal Seeds Retinal tumor IIRC Laterality Patient (dose) Intravitreal chemotherapy Intraarterial chemotherapy - Mel / Topo + + + D Unilateral #1 (2.0x10 9 vp) - - + - + D Bilateral #2 (2.0x10 10 vp) Mel Carbo /Mel / Topo + - + C Bilateral #4 (2.0x10 10 vp) Mel / Topo - + - + D Unilateral #5 (2.0x10 10 vp) Carbo /Mel - + - + D Bilateral #8 (2.0x10 10 vp) Topo - + + + D Bilateral #9 (2.0x10 10 vp) Topo Carbo /Mel / Topo + - - C Unilateral #11 (2.0x10 10 vp) Topo Carbo /Mel / Topo + - + B Bilateral #12 (2.0x10 10 vp) Topo Carbo /Mel / Topo + - + D Unilateral #13 (2.0x10 10 vp) Conclusions Acknowledgements VCN - 01 was well tolerated, uveitis being the most common adverse effect. VCN - 01 did not cause retinal toxicity. The response in these heavily pre - treated eyes was encouraging. Safety Profile Grade 3 All Grades Description/Nature of the event (MedDRA PT) MedDRA System Organ Class (SOC) % n % n 44% 4 78% 7 Uveitis Eye disorders 0% 0 11% 1 Eye oedema Eye disorders 0% 0 11% 1 Conjunctival hyperemia Eye disorders 0% 0 11% 1 Eye inflammation Eye disorders Adverse reactions (events associated with VCN - 01, monotherapy) Number events VCN - 01 Relatedness Description/Nature of the event (MedDRA PT) MedDRA System Organ Class (SOC) 3 Related Uveitis Eye disorders 1 Non - related Retinal detachment Eye disorders 1 Non - related Vitreous and anterior chamber haemorrhage Eye disorders 1 Non - related Enucleation Eye disorders Serious Adverse Events Staining of VCN - 01 viral proteins in healthy retina Patient #2 (germline mutation) Conserved retina Calcified tumor area Conserved retina Tumor area Conserved retina Tumor area Conserved retina Necrotic tumor Patient #9 (germline mutation) Patient #8 (germline mutation) Patient #1 Other safety evidences: No evidence of extraocular relapse No systemic toxicities occurred. VCN - 01 caused changes in electroretinograms due to turbidity, but they were reversible 2 doses of VCN - 01 at 2E+10 vp/eye was defined as the RP2D From the second patient onwards, all patients received pre - emptive oral and/or topical steroids to prevent uveitis. Uveitis was improved or resolved at day 42 in most patients. One patient with G3 uveitis did not receive the second dose because of medical decision and also experienced glaucoma requiring treatment. VCN - 01 does not replicate in healthy retinal tissue of patients with either somatic or germline Rb mutation No DLT observed Preliminary E fficacy Evaluation Status at Enucleation Enucleation Date Final RB_RECIST Response at D42 Vitreous seed response after Dose 2 Tumor response after Dose 2 Vitreous seed response after Dose 1 Tumor response after Dose 1 Number of doses Patient (dose) Tumor progression D44 SD SD SD SD SD 2 #1 (2.0x10 9 vp) Tumor progression D62 PR PR PR PR PR 2 #2 (2.0x10 10 vp) n.a No PR PR SD PR PR 3 #4 (2.0x10 10 vp) Lack of response D56 SD SD SD SD SD 2 #5 (2.0x10 10 vp) Tumor progression D170 PR PR SD PR SD 2 #8 (2.0x10 10 vp) Tumor progression D37 PD SD SD SD SD 2 #9 (2.0x10 10 vp) n.a No PR PR - PR - 2 #11 (2.0x10 10 vp) n.a No PR - - PR PR 1 #12 (2.0x10 10 vp) Tumor progression D93 SD SD SD SD SD 2 #13 (2.0x10 10 vp) Expected enucleation w/o response: D37 - 43; Subsequent eye - conservative treatment was administered to patients #4, #8, #11, #12 and #13 Analysis of VCN - 01 presence on biological samples Active Tumor (vitreous seeds) 3 - years old Bilateral retinoblastoma (with germline Rb 1 mutation), with 1 st eye already enucleated . Previous treatments : Systemic chemotherapy CBP/VP - 16 /VCR (followed by intraarterial dosing of topotecan/melphalan) . Tumor relapse 9 months later Intravitreous melphalan : NO RESPONSE . Calcified Tumor (from previous treatments) D0 (pre - injection) D28 D64 D189 D240 Case - study Patient #3 Absence of VCN - 01 genomes in blood . Persistence of VCN - 01 genomes in aqueous humor correlates with vitreous seed presence . Our more since appreciation to the patients and their families that participated in this trial. This work has been partially funded by Cure4RB Project - RETOS 2015 (MiNECO, Spain) 5 patients with partial response, 3 with stable disease and 1 with progressive disease. The eyes of 3 out of 5 patients with PR are preserved with vision after receiving eye - conservative therapy (follow - up 12 - 49 mont hs)