Ku, Geoffrey

356 Background: Autologous anti-claudin 18.2 (CLDN18.2) CAR T cell, satricabtagene autoleucel (satri-cel), was developed to treat solid tumors. We report the completed results of the Phase 1b ELIMYN18.2 study (Cohort A) in gastric/gastroesophageal junction (GC/GEJ) and pancreatic cancer (PC). Methods: This single-arm, open-label, Phase 1b/2 study (NCT04404595) evaluated the safety and efficacy of satri-cel in patients with CLDN18.2-positive advanced GC/GEJ or PC. Cohort A consisted of a modified 3+3 design. After a conditioning regimen of fludarabine, cyclophosphamide, and nab-paclitaxel, patients were administered 1-3 cycles of satri-cel. The primary objectives were safety and determination of the recommended Phase 2 dose (RP2D). Adverse Events (AEs) were graded per CTCAE 5.0, objective response rate (ORR), and clinical benefit rate (CBR) including CR, PR, and ≥6-month SD were assessed by the investigator per RECIST 1.1. Results: As of May 14, 2023, twenty-four patients underwent leukapheresis in Cohort A. Nineteen patients (7 GC/GEJ and 12 PC) with a median of 3 (range: 1-8) prior therapeutic lines had satri-cel at three dose levels (DLs) between 250×106 and 600×106 cells. Seven patients received a 2nd dose and two patients received a 3rd dose of satri-cel at a median of 113 and 259 days, respectively, post-first infusion. All 19 patients experienced at least one AE. No DLTs occurred and 17 patients experienced cytokine release syndrome (CRS). Two cases of Grade 3 CRS were reported, and all other CRS were Grade 1 or 2. Two Grade 1 immune effector cell-associated neurotoxicity syndrome (ICANS) occurred. All CRS and ICANS were resolved. No severe gastrointestinal-related AEs were found. No increased toxicities were reported after any reinfusion. No satri-cel treatment-related death occurred. For all patients, the best ORR was 26.3%, the median DOR was 3.7 months and the CBR was 42.1%. The median PFS was 5.2 months, and overall survival was 12.8 months (95% CI 5.7-NE) after leukapheresis, and the median PFS was 3.3 months, and overall survival was 8.9 months (95% CI 3.3-NE) after the first infusion. In the GC/GEJ group, the ORR was 42.9% (3/7), the median DOR was 6.9 months and the CBR was 57.1%. In the PC group, the ORR was 16.7% (2/12), the median DOR was 3.4 months and the CBR was 33.3%. An ORR of 42.9% (3/7) and a CBR of 71.4% were reported at the DL3 of 600×106 cells which was selected as RP2D. At DL3, one GC patient achieved a CR and two PC patients had PR, suggesting the PC group achieved an ORR of 40% (2/5) and the GC group achieved an ORR of 50% (1/2). In addition, tumor shrinkage was detected in 73.7 % (14/19) of patients. Conclusions: The safety profile and therapeutic efficacy of satri-cel were shown to be promising in heavily pretreated patients with CLDN18.2-positive advanced GC/GEJ and PC . In the Phase 2 study, the first patient with GC received satri-cel in May 2023. Clinical trial information: NCT04404595 .

Gastrointestinal (GI) cancers, including esophageal, gastroesophageal junction, gastric, duodenal and distal small bowel, biliary tract, pancreatic, colon, rectal, and anal cancer, comprise a heterogeneous group of malignancies that impose a significant global burden. Immunotherapy has transformed the treatment landscape for several GI cancers, offering some patients durable responses and prolonged survival. Specifically, immune checkpoint inhibitors (ICIs) directed against programmed cell death protein 1 (PD-1), either as monotherapies or in combination regimens, have gained tissue site-specific regulatory approvals for the treatment of metastatic disease and in the resectable setting. Indications for ICIs in GI cancer, however, have differing biomarker and histology requirements depending on the anatomic site of origin. Furthermore, ICIs are associated with unique toxicity profiles compared with other systemic treatments that have long been the mainstay for GI cancer, such as chemotherapy. With the goal of improving patient care by providing guidance to the oncology community, the Society for Immunotherapy of Cancer (SITC) convened a panel of experts to develop this clinical practice guideline on immunotherapy for the treatment of GI cancer. Drawing from published data and clinical experience, the expert panel developed evidence- and consensus-based recommendations for healthcare professionals using ICIs to treat GI cancers, with topics including biomarker testing, therapy selection, and patient education and quality of life considerations, among others.

4009 Background: Interim analysis of a global, phase 2 KEYNOTE-059 study (NCT02335411) reported manageable safety and promising antitumor activity for pembro alone or pembro + chemo in pts with G/GEJ cancer. Here we report long-term efficacy and safety data of all cohorts. Methods: Pts with recurrent or metastatic G/GEJ adenocarcinoma were enrolled in 3 cohorts. Cohort 1 pts (PD-L1–positive or –negative) received pembro alone after ≥2 prior lines of therapy. Cohort 2 pts (PD-L1–positive or –negative) received pembro + cisplatin (80 mg/m2 day 1) + 5-fluorouracil (800 mg/m2 days 1-5 Q3W) or capecitabine (in Japan only, 1000 mg/m2 twice daily) as first-line. Cohort 3 pts (PD-L1–positive, combined positive score ≥1% using the PD-L1 IHC 22C3 pharmDx assay) received pembro alone as first-line. All pts received pembro 200 mg Q3W for up to 2 years. End points included safety, ORR, DOR, and OS. Results: At data cutoff (Aug 8, 2018), median (range) follow-up was 6 (1-38), 14 (2-40), and 21 (2-36) months for cohorts 1 (n = 259), 2 (n = 25), and 3 (n = 31), respectively. In cohort 1, confirmed ORR (95% CI) was 11.6% (8-16) overall, 15.5% (10-22) in PD-L1–positive, and 6.4% (3-13) in PD-L1–negative tumors. In cohort 2, confirmed ORR was 60.0% (39-79) overall, 73.3% (45-92) in PD-L1–positive, and 37.5% (9-76) in PD-L1–negative tumors. In cohort 3, confirmed ORR was 25.8% (12-45). Median (range) DOR in months was 16.1 (2-35+), 4.6 (3-37+), and not reached (2.1-32.5+) in cohorts 1, 2, and 3, respectively. OS at 1 year/2 years was 24.6%/12.5%, 52%/32%, and 63.6%/40.1% in cohorts 1, 2, and 3, respectively. In cohorts 1, 2, and 3, grade 3-5 treatment-related adverse event (TRAE) incidence was 46 (18%), 20 (80%), and 8 (26%) respectively. TRAEs led to discontinuation in 6 (2%) and 3 (12%) pts in cohorts 1 and 2, respectively, and to death in 2 (1%) pts in cohort 1. No TRAEs led to discontinuation or death in cohort 3. Conclusions: These updated results demonstrate manageable safety, durable clinically meaningful activity of pembro in heavily pretreated pts, and promising efficacy of first-line pembro (alone or + chemo) in pts with advanced G/GEJ cancer. Clinical trial information: NCT02335411.