Casado, Antonio

2630 Background: Human papillomavirus 16 (HPV-16) infection is associated with several cancer types with limited treatment options in the locally R/M settings. Furthermore, immune checkpoint inhibitors have limited activity against advanced HPV-cancers. TG4001 is a viral vector vaccine targeting HPV E6 and E7 antigens. We have previously shown in a single-arm, dose finding phase 1 study that TG4001 combined with PD-L1 blockade using avelumab was safe and associated with a response rate of 22%. Herein we report preliminary data on immunogenicity and clinical activity of TG4001 in a randomized phase 2 study comparing TG4001 plus avelumab versus avelumab alone. Methods: Eligibility criteria: R/M HPV16+ anogenital cancer including cervical, vulvar, vaginal, penile, and anal cancers; immunotherapy naïve and with no more than one prior line of chemotherapy. HPV-16 positivity was required and centrally determined using a PCR based assay. Patients were randomly assigned 1:1 to receive either TG4001 plus avelumab (Vaccine arm) or avelumab alone. Randomization was stratified by tumor type (cervical, anal, genital). TG4001 was administered s.c at 5·107 pfu, Q1w for 5 weeks, then Q2w until month 6 followed by Q12w until progressive disease and avelumab i.v at 800 mg Q2w until progressive disease. PBMCwere collected at baseline, day 43 and day 85 to assess T-cell responses against E6 and E7 antigens using ex-vivo IFNg ELISPOT and immunophenotyping of circulating T cells. Vaccine immune response (IR) was defined as onset of a new T-cell response against either antigen or amplification of a pre-existing response under treatment. Tumor response was assessed using RECIST 1.1. Results: 59 pts had been randomized by the time of data cut-off. IR was assessed in 24 pts in the vaccine arm and 16 pts in the avelumab arm. T cells against E6 or E7 antigens at baseline were rare with only 4 pts having a low intensity ELISPOT readout against either target prior to initiation of treatment. 11/24 pts in the vaccine arm had an IR, while none of the patients in the avelumab arm had an IR. Occurrence of IR was detected at day 43 and tended to gain in intensity at D85. In the vaccine arm, IR was associated with tumor response with 3 clinical responders among 11 pts with positive IR versus 1 response observed among the 13 patients without IR. Conversely, only 2 progressive disease pts among 11 positive IR compared favorably to the 6/13 vaccine arm pts with no IR. Remarkably, a complete clinical response was observed in a vaccine treated pt exhibiting the strongest E6 and E7 IR. Conclusions: TG4001 can induce a de novo immune response against HPV-16 antigens E6 and E7 in advanced HPV-16 cancers. The data suggest that these IRs are associated with anti-tumor response and that TG4001 vaccination in combination with ICI has the potential to drive clinical benefit in R/M anogenital cancers. Clinical trial information: NCT03260023 .

PURPOSE Antitumor activity in preclinical models and a phase I study of patients with dedifferentiated liposarcoma (DD-LPS) was observed with selinexor. We evaluated the clinical benefit of selinexor in patients with previously treated DD-LPS whose sarcoma progressed on approved agents. METHODS SEAL was a phase II-III, multicenter, randomized, double-blind, placebo-controlled study. Patients age 12 years or older with advanced DD-LPS who had received two-five lines of therapy were randomly assigned (2:1) to selinexor (60 mg) or placebo twice weekly in 6-week cycles (crossover permitted). The primary end point was progression-free survival (PFS). Patients who received at least one dose of study treatment were included for safety analysis (ClinicalTrials.gov identifier: NCT02606461 ). RESULTS Two hundred eighty-five patients were enrolled (selinexor, n = 188; placebo, n = 97). PFS was significantly longer with selinexor versus placebo: hazard ratio (HR) 0.70 (95% CI, 0.52 to 0.95; one-sided P = .011; medians 2.8 v 2.1 months), as was time to next treatment: HR 0.50 (95% CI, 0.37 to 0.66; one-sided P < .0001; medians 5.8 v 3.2 months). With crossover, no difference was observed in overall survival. The most common treatment-emergent adverse events of any grade versus grade 3 or 4 with selinexor were nausea (151 [80.7%] v 11 [5.9]), decreased appetite (113 [60.4%] v 14 [7.5%]), and fatigue (96 [51.3%] v 12 [6.4%]). Four (2.1%) and three (3.1%) patients died in the selinexor and placebo arms, respectively. Exploratory RNA sequencing analysis identified that the absence of CALB1 expression was associated with longer PFS with selinexor compared with placebo (median 6.9 v 2.2 months; HR, 0.19; P = .001). CONCLUSION Patients with advanced, refractory DD-LPS showed improved PFS and time to next treatment with selinexor compared with placebo. Supportive care and dose reductions mitigated side effects of selinexor. Prospective validation of CALB1 expression as a predictive biomarker for selinexor in DD-LPS is warranted.

5593 Background: We conducted an international survey to evaluate the differences in the systemic, radiotherapeutic and operative management of endometrial cancer (EC) in different regions of the world. Methods: In 2009 avalidated 15-item-questionnaire regarding surgical and adjuvant procedures of EC was sent to all German gynaecological clinics and in 2010 the English adapted questionnaire was set online as well as sent per post in most major gynaecological cancer societies. Results: 316 German institutions and 302 Institutions from 24 countries participated. We combined the different countries into regional groups: Central Europe (CE), southern Europe (SE), Asia and USA/UK. In Asian countries and in CE a lymph node dissection (LND) was performed routinely in 72.8% and in 55.6% of the cases, whereas in the USA/UK and in SE a LND was done mainly in selected cases when specific risk factors such as high-grade or non-endometrioid-histology applied (62.8% and 72.5%) than routinely (p < 0.001). A systematic pelvic and paraaortic LND was performed most frequently in CE 91.0%, in SE 76.9%, in Asia 70.9% and in USA/UK 68.6% (p < 0.001). A systematic LND with the intention of both adequate staging and for therapeutic value was performed in countries of central Europe to 74.6% and in Asia to 67.2%. In USA/UK the LND was seen merely as a staging instrument by 53.5% (p < 0.001). The LND was performed up to renal veins in CE in 86.8%, in Asia in 80.8%, in USA/UK in 51.2% and in SE in 45.1 %. A significant difference war found in the treatment for FIGO stage I (high risk factors (high grade, L1,V1)) and stage II disease between the countries: chemotherapy was applied in 84.8% of the participated centers in Asia,42.3% in SE, 21.2% in CE and only 13.6% in USK/UK (p<0.001).Vaginal brachytherapy was indicated as follows: USA/UK 84.1%, CE 78.8%, SE 78.8%, Asia 5.6% (p < 0.001). Conclusions: There is a large variety in the operative therapy and the clinical management of EC in different regions of the world. Future international prospective trials, will be necessary to improve and harmonize the evidence based treatment guidelines for EC- disease.

5087 Background: Indication, technique and extent of lymph-node-dissection (LND) in endometrial cancer (EC) remains controversial and is strongly debated in cancer community. We conducted a national- and at a second step an international-survey evaluating the current status-quo of the surgical and medical management of EC. Methods: A validated 15-item-questionnaire regarding surgical and adjuvant procedures of EC was sent to all major gynaecological cancer societies and study groups worldwide. The questionnaire could also be answered online. Results: In a phase-I-national trial, the questionnaire was validated on basis of 316 German institutions. On the phase-II-international survey a total of 302 questionnaires were answered from 24 countries, mainly from Japan (38.7%), Spain (8.3%), Austria (7%), United-Kingdom (6.3%), Italy (6%), USA (4.3%) and Canada (4%). The vast majority of the participating clinics were academic (62.8%), while 75.2% of them belonged to gynaecology. Only 0.7% of the clinics internationally reported never performing LND in EC. 62.3% of the clinics perform both a pelvic and paraaortic lymph node dissection. 59.1% of the participants performed a systematic lymph node dissection with the intention of both adequate staging and for therapeutic value. 15.05% of the clinics perform LND up to the common-iliac-arteries, 9.03% up to the inferior-mesenteric-artery and 70.6% up to the renal-veins. The most common risk-factors to indicate LND were: high-grading (93%), non-endometrioid-histology (90.1%), lymphovascular-invasion (55.3%), blood-vessel invasion (45.4%) and tumor-diameter >2cm (38.4%). For advanced stage III&IV disease the vast majority (60% and 80%, respectively) of the physicians indicated systemic chemotherapy alone. Conclusions: This study presents the large variety in clinical management of EC worldwide, underlining so the high need of future prospective randomised trials which will establish standard and evidence based treatment guidelines for EC- disease.