Kim, Se Hyun

4028 Background: T-cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domains (TIGIT) inhibitor in combination with an anti-programmed cell death protein 1 (PD-1) antibody has shown antitumor activity in solid tumors. AdvanTIG-105 (NCT04047862) is a phase 1/1b open-label study designed to assess the safety and preliminary antitumor activity of OCI, an anti-TIGIT monoclonal antibody (mAb), + TIS, an anti-PD-1 mAb, in pts with unresectable, locally advanced or metastatic solid tumors. In the dose-escalation part, OCI + TIS was well tolerated with preliminary antitumor activity observed, and the recommended phase 2 dose (RP2D) of OCI 900 mg intravenously (IV) every three weeks (Q3W) + TIS 200 mg IV Q3W was established. We report results from the dose-expansion part (GC/GEJC Cohort 9) of the AdvanTIG-105 study. Methods: Eligible pts had histologically/cytologically confirmed stage IV GC/GEJC. Pts were excluded if they had squamous cell, undifferentiated or other histological types of GC, had GC/GEJC with positive HER2 expression, or if they had received any prior therapy for metastatic disease. Pts received either the RP2D of OCI + TIS with oxaliplatin + capecitabine Q3W for 6 cycles (C), followed by maintenance therapy with the RP2D of OCI + TIS, + capecitabine Q3W, or the RP2D of OCI + TIS with cisplatin + 5-fluorouracil Q3W for 6 C. Treatment continued until disease progression, intolerable toxicity, or withdrawal of consent. The primary endpoint was investigator-assessed overall response rate (ORR) per RECIST v1.1. Secondary endpoints included progression-free survival (PFS), duration of response (DoR), disease control rate (DCR) per RECIST v1.1, and safety. Results: As of September 29, 2022, 60 pts with a median age of 61.5 years (range 35-82) were enrolled; 59 were efficacy evaluable. Median study follow-up was 31.1 weeks (range 1.4-78.4). ORR was 50.8% (95% CI: 37.5, 64.1); DCR was 84.7% (95% CI: 73.0, 92.8) with a median DoR of 8.1 months (95% CI: 4.5, not evaluable [NE]). Median PFS was 8.2 months (95% CI: 5.8, NE). In a subgroup analysis, ORR in pts with PD-L1 tumor area positivity (TAP) score ≥5% (n = 27) was 59.3% (95% CI: 38.8, 77.6), and 50.0% (95% CI: 30.7, 69.4) in pts with PD-L1 TAP < 5% (n = 28). All 60 pts reported ≥1 treatment-emergent adverse event (TEAE), the most common being anemia (43.3%) and platelet count decreased (41.7%). In total, 43 pts (71.7%) had ≥grade 3 TEAEs and 28 (46.7%) had serious adverse events. TEAEs leading to discontinuation of TIS and OCI occurred in 5 (8.3%) pts. TEAEs led to death in 2 (3.3%) pts; one event (neutropenic sepsis) was related to chemo, while the other (pulmonary embolism) was not treatment related. Conclusions: OCI 900 mg + TIS 200 mg + chemo was generally well tolerated and showed encouraging antitumor activity in pts with stage IV GC/GEJC. Clinical trial information: NCT04047862 .

Abstract Background: PD-L1 blockade with durvalumab (D) is approved as second-line therapy in platinum-refractory metastatic urothelial cancer (mUC). Adding CTLA-4 blockade with tremelimumab (T) may improve responses, particularly in pts with low PD-L1 expression. Here we report safety and efficacy in the mUC cohort of the dose-expansion phase of a phase I, multicenter, open-label study of D+T in pts with advanced solid tumors (NCT02261220). Methods: Pts with platinum-refractory mUC received D 20 mg/kg + T 1 mg/kg Q4W for 4 months, followed by D 10 mg/kg Q2W for a total of 12 months of treatment. The primary objectives were safety in the mUC cohort and antitumor activity in the subgroup with tumor cell and immune cell PD-L1 expression &lt;25% (assessed by SP263 IHC assay). Secondary objectives included antitumor activity per RECIST v1.1 in other subgroups. Results: As of Oct 20 2017, 168 pts received treatment and had ≥24 weeks' follow-up. Median age was 65.5 yr (range, 35-85), 78.0% were male, 81.0% had visceral metastases (32.1% liver metastases) and 32.1% had received &gt;1 prior line of chemotherapy. Median duration of follow-up was 11.6 mo. Treatment-related AEs occurred in 75.6% of pts and were Grade 3-4 in 28.6%. One pt died due to a treatment-related AE (pulmonary hemorrhage). Treatment-related AEs led to discontinuation of therapy in 11.9% of pts. Confirmed objective response rate (ORR) was 35/168 (20.8%) including 4 CRs. Responses occurred early (median 1.8 mo) and are durable (median DOR not reached, range 1.9-24.9 mo). At 6 months, the PFS rate was 25.4% and the OS rate was 60.9%. Median PFS was 1.9 mo and median OS was 9.5 mo. Clinical activity was seen regardless of PD-L1 status, but patients with either tumor or immune cell expression ≥25% had numerically higher response rates (29.4% vs 15.1%) and 6-month OS rates than those with &lt;25% expression (Table). Conclusions: D+T had a manageable safety profile and encouraging antitumor activity and survival rate in previously treated mUC regardless of PD-L1 status. Response and survivalPD-L1 ≥25% (n=68)PD-L1 &lt;25% (n=86)PD-L1 unknown (n=14)Total (N=168)Confirmed ORR (CR+PR)(95% CI), %29.4 (19.0-41.7)15.1 (8.3-24.5)14.3 (1.8-42.8)20.8 (15.0-27.8)Ongoing ORR, %60.092.310074.3Disease control rate (CR+PR+SD≥24 weeks) (95% CI), %32.4 (21.5-44.8)24.4 (15.8-34.9)42.9 (17.7-71.1)29.2 (22.4-36.7)Median PFS, months (95% CI)3.5 (1.9-3.7)1.8 (1.8-1.9)4.9 (1.8-NE)1.9 (1.8-3.4)PFS 6-month rate, %26.122.638.525.4Median OS, months (95% CI)*18.9 (8.1-NE)8.0 (4.8-10.0)16.4 (7.3-16.4)9.5 (8.1-18.9)OS 6-month rate, %66.451.991.760.9NE, not estimable *Should be interpreted with caution due to limited follow-up at data cutoff Citation Format: Arjun V. Balar, Amit Mahipal, Enrique Grande, Victor M. Villalobos, Sebastien Salas, Taek Won Kang, Se Hyun Kim, Thomas Powles, Frank Tsai, Aung Naing, Albiruni Razak, Yohann Loriot, Ji Youl Lee, Sang Joon Shin, Rafael Morales-Barrera, Natasha Angra, Feng Xiao, Shaad Abdullah, Michiel S. Van der Heijden. Durvalumab + tremelimumab in patients with metastatic urothelial cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr CT112.