424 Background: This study evaluated the strategy of dose-dense chemotherapy plus a PD-1 inhibitor with selective organ-preservation in patients with advanced esophageal squamous cell carcinoma (ESCC). Methods: Patients with locally advanced or metastatic (confined to the supraclavicular lymph nodes) ESCC were enrolled to receive treatment with a PD-1 inhibitor plus albumin bound-paclitaxel, cisplatin and 5-FU every two weeks. After six cycles of treatment, patients with clinical complete response (cCR) confirmed by computed tomography (CT), endoscopy and biopsy underwent an organ-preserving strategy with continuation of immunochemotherapy. The primary endpoint was cCR rate in the intention-to-treat population. A post hoc analysis was also conducted in patients with advanced ESCC who had a best response of CR after immunochemotherapy from three prospective studies we previously reported. Consecutive patients who had not received esophagectomy prior to immunochemotherapy, and had durable CR as confirmed by imaging, endoscopy with or without biopsy were identified to provide supporting evidence for the organ-preserving strategy. Results: A total of twenty patients were enrolled. At data cut-off (September 12, 2024), eight patients fulfilled the criteria of cCR (40%), while six patients actually adopted the organ-preserving strategy. 75% of the patients experienced ≥ grade 3 treatment-related adverse events (TRAEs), most commonly neutropenia and leukopenia. All TRAEs were managed with appropriate medical care. In the post hoc analysis, out of 71 patients who had a best response of CR to immunochemotherapy in three previous trials, sixteen consecutive patients who had not received esophagectomy before immunochemotherapy, and remained CR assessed with CT at data cut-off were identified. Although endoscopy was not mandatory during follow-up, twelve patients underwent endoscopic exams, and none of them had suspected tumor with endoscopic visualization. Biopsies were taken for eight patients, and were all negative for tumor. The median follow-up for these twelve patients reached 42.7 months, suggesting a long-term disease-free survival after immunochemotherapy. Conclusions: Dose-dense nab-paclitaxel, cisplatin and 5-FU combined with a PD-1 inhibitor showed encouraging cCR rate and manageable safety, making organ-preservation a possible subsequent approach in patients with advanced ESCC. Clinical trial information: ChiCTR2300072992.

333 Background: Docetaxel has demonstrated promising activity in gastric cancer, both as monotherapy and in combination with other agents. Albumin-bound docetaxel (HB1801) is a new kind of taxane and has many advantages compared with docetaxel. Previous phase I study has demonstrated that HB1801 showed preliminary efficacy in patients with gastric cancer. Methods: In this phase II study, eligible patients were aged 18-75 years with histologically confirmed gastric or gastroesophageal junction (G/GEJ) adenocarcinoma, who progressed on at least first line of combined chemotherapy of platinum and fluorouracil. Patients were randomized (1:1) to receive HB1801 (100 mg/m 2 ) or docetaxel (Taxotere, 75 mg/m 2 ) administered every 3 weeks by intravenous infusion. Stratified factors included previous treatment with immunotherapy (yes or no) and ECOG PS (0 or 1). Primary endpoint was progression free survival (PFS). Results: As of June 25, 2024, 128 patients were randomized to the HB1801 group ( n =65) or the docetaxel group ( n =63). The two groups were comparable on baseline characteristics. Overall, the median age was 59.0 (range 27-75) years, 106 (82.8%) patients had ECOG PS of 1. 76 (59.4%) patients had received previous treatment with immunotherapy. 76 (59.4%) patients had ≥ 2 metastatic sites. Median PFS was 4.0 months (95%CI 2.8-4.2) with HB1801 versus 2.7 months (95%CI 1.8-3.0) with docetaxel, HR = 0.81(95%CI 0.53, 1.21). Objective response rate and disease control rate were 21.5% (1CR and 13 PRs, 95%CI 12.3-33.5) and 56.9% (20 SDs, 95%CI 44.0-69.2) in the HB1801 group, compared with 14.3% (1 CR and 8 PRs, 95%CI 6.8-25.4) and 42.9% (17 SDs, 95%CI 30.5-56.0) in the docetaxel group. Median overall survival was 11.3 months with HB1801 versus 7.8 months with docetaxel (HR = 0.59 [95%CI 0.35, 1.01], p=0.025). Treatment-related adverse events (TRAEs) occurred in 93.8% of patients receiving HB1801, and 93.7% of patients receiving docetaxel. Alopecia (46.2% vs. 39.7%), fatigue (43.1% vs 23.8%), anemia (40.0% vs 39.7%), hypoalbuminemia (29.2% vs 12.7%), decreased appetite (21.5% vs 12.7%), peripheral edema (16.9% vs 12.7%) and nausea (15.4% vs 19.0%) were the most common TRAEs in the HB1801 group and the docetaxel group. 20 patients (30.8%) in the HB1801 group and 19 patients (30.2%) in the docetaxel group experienced ≥grade 3 TRAEs, with the most common being anemia and fatigue. 3 patients in the docetaxel group experienced treatment emergent adverse events (TEAEs) leading to death, which one was considered to be treatment-related. No patients in the HB1801 group had TEAEs leading to death. No new safety signal was observed in HB1801 group. Conclusions: Compared with Taxotere, HB1801 results in 41% reduction in risk of death with a manageable safety profile in patients with previously treated advanced G/GEJ cancer. Clinical trial information: NCT05705635 .

440 Background: Approximately 12–23% G/GEJC patients have human epidermal growth factor receptor 2 (HER2)-positive disease. Despite survival benefit from combination therapy with trastuzumab and chemotherapy, the prognosis remains unsatisfactory; more effective treatments are needed. This phase 2 study is evaluating the combination of HLX22 (an anti-HER2 monoclonal antibody targeting a different epitope than trastuzumab), trastuzumab, and XELOX chemotherapy as first-line treatment for patients with advanced/metastatic G/GEJC. Following the most recent report of 17 to 18 patients in each group at ASCO 2024 Annual Meeting, herein we present the updated efficacy and safety results with 31 patients in each group. Methods: Patients with locally advanced or metastatic HER2-positive G/GEJC and no prior systemic antitumor therapy were enrolled. Herein reported are results from Stage 2 of the study. Eligible patients were randomized to receive either HLX22 + trastuzumab + XELOX or placebo + trastuzumab + XELOX in 3-week cycles. Primary endpoints were independent radiology review committee (IRRC)-assessed progression-free survival (PFS) and objective response rate (ORR) per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1. Secondary endpoints included other efficacy and safety endpoints. Results: As of June 30, 2024, 62 patients were randomized to the respective groups (31 vs 31), of whom 51 (82.3%) patients were male. Median follow-up duration was 20.3 and 24.0 months for the respective groups. The efficacy results are shown in the table. Treatment-emergent adverse events (TEAEs) were reported in 30 (96.8%) and 31 (100%) patients, and HLX22- or placebo-related TEAEs of grade 3 or higher were reported in 9 (29.0%) and 6 (19.4%) patients in the respective groups. One patient (3.2%) in the placebo + trastuzumab + XELOX group had a grade 5 HLX22-/placebo-related TEAE. Conclusions: With a manageable safety profile, the addition of HLX22 to first-line treatment with trastuzumab plus XELOX conferred survival benefit for HER2-positive G/GEJC patients. Clinical trial information: NCT04908813 . Updated efficacy, IRRC-assessed. HLX22 + trastuzumab + XELOX (n=31) placebo + trastuzumab + XELOX (n=31) Median PFS, months (95% CI) NR (23.49, NE) 8.3 (5.7, 12.7) HR (95% CI) 0.2 (0.06, 0.45) - 12-month PFS rate (95% CI) 73.8 (50.3, 87.4) 34.2 (12.0, 58.1) 24-month PFS rate (95% CI) 61.5 (30.4, 82.0) 24.0 (10.3, 27.3) Confirmed ORR, % (95% CI) 87.1 (70.2, 96.4) 80.6 (62.5, 92.5) Week 48 ORR, % (95% CI) 38.7 (21.8, 57.8) 9.7 (2.0, 25.8) Median OS, months (95% CI) NR (17.6, NE) 22.0 (10.6, NE) HR (95% CI) 0.5 (0.20, 1.21) - Median DOR, months (95% CI) NR (22.1, NE) 9.7 (4.6, 20.0) HR (95% CI) 0.1 (0.04, 0.41) - CI, confidence interval. NE, not evaluable. NR, not reached.

463 Background: Immune checkpoint inhibitors combined with chemotherapy had become the first-line standard treatment for advanced ESCC and cadonilimab, as a bispecific antibody simultaneously targeting PD-1 and CTLA-4, may further boost anti-tumor activity with a satisfied safety profile. Here, we present the updated data for the safety and efficacy of cadonilimab combination therapy as the first-line treatment in advanced ESCC. The correlation between DNA methylation and clinical response was also investigated. Methods: Treatment-naïve patients (pts) with unresectable locally advanced or metastatic ESCC were enrolled. Cadonilimab (10mg/kg, iv, d1, q3w) combined with paclitaxel or nab-paclitaxel (175 mg/m 2 , iv, d1, q3w) and cisplatin (65 to 75 mg/m 2 , iv, d1, q3w) were administrated for up to 6 cycles, then Cadonilimab (10mg/kg, iv, d1, q3w) monotherapy continued as maintenance until progressive disease or unacceptable toxicity, with a maximum of 24 months. The primary endpoint was objective response rate (ORR). Secondary endpoints were progression-free survival (PFS), overall survival (OS), disease control rate (DCR) and safety. Plasma cell-free DNA samples were collected before and after treatment and prepared for methylation level sequencing. Results: As of September 20, 2024, 43 pts were enrolled with a median age of 61 years (range 44-75), 81.4% were male, 39.5% had PD-L1 CPS≥10 and 95.3% had metastatic diseases. All pts were evaluable for safety and efficacy. The ORR was 81.4% (95%Cl: 66.1%-91.1%) and DCR was 97.7% (95%Cl: 86.2%-99.9%). The median PFS (mPFS) was 7.05 months (mo) (95%Cl: 5.86-8.24) and OS analysis was immature. In the PD-L1 CPS≥10 pts, the ORR was 100.0% (95%Cl: 77.1%-100.0%) and mPFS was 7.05 mo (95%Cl: 5.19-8.91). In the PD-L1 CPS＜10 pts, the ORR was 77.3% (95%Cl: 54.2%-91.3%) and mPFS was 7.05 mo (95%Cl: 5.87-8.24). Six hyper-methylated CpG sites, EPTIN9、PKNOX2、DLEU7、SOX7、CNRIP1 and LINC00554 might be the candidate biomarkers as the mean pretreatment methylation levels were significantly higher in the PR pts than those in the non-PR pts (p=7.8×10 -7 ). Grade 3-4 treatment-related adverse events (TRAEs) were reported in 44.2% (19/43) pts, mainly including neutropenia (25.6%), leukopenia (9.3%) and hyponatremia (7.0%). The infusion-related reactions (IRR) occurred in 14.0% (6/43) and grade ≥3 IRR occurred in 4.7% (2/43) pts. 7 pts discontinued cadonilimab administration due to TRAEs. Conclusions: The updated results suggested that bispecific antibody cadonilimab combined with taxane and cisplatin as first-line treatment continued to show encouraging anti-tumor activity and manageable safety in pts with advanced ESCC. DNA methylation level might be a potential biomarker for guiding patient outcomes. Clinical trial information: NCT05522894 .

BackgroundThe combination of anti-PD-1 antibody serplulimab and chemotherapy is considered standard first-line therapy for advanced esophageal squamous cell carcinoma (ESCC), but few later-line treatments are available. Here we evaluated the therapeutic efficacy of the recombinant, humanized anti-EGFR antibody HLX07 when used alone or together with serplulimab and chemotherapy against advanced ESCC.MethodsThis open-label, non-randomized, two-cohort, phase 2 trial involved patients 18-75 years old with histologically or cytologically confirmed locally advanced, unresectable, or metastatic ESCC, and an Eastern Cooperative Oncology Group performance status of 0-1. Patients who had failed first-line immuno-chemotherapy or at least two lines of other systemic therapy received HLX07 monotherapy intravenously at a dose of 1,000 mg once every 2 weeks (Q2W). Patients with no prior systemic therapy received HLX07 (1,000 mg, day 1) and serplulimab (200 mg, day 1) intravenously Q2W for up to 2 years, concurrently with cisplatin (50 mg/m2, day 1) for up to 8 cycles and 5-fluorouracil (1,200 mg/m2, days 1-2) for up to 12 cycles intravenously Q2W. The primary endpoints were progression-free survival (PFS) and objective response rate (ORR).ResultsOverall, 50 patients were enrolled. In the HLX07 monotherapy group, ORR was 15.0% (3/20), and the median PFS was 1.5 months (95% confidence interval [CI], 1.3 to 3.7). The median duration of response was not reached, and the rate of patients showing an objective response lasting at least 6 months was 66.7% (95% CI, 5.4 to 94.5). Two (10.0%, 2/20) patients experienced grade 3-4 treatment-related adverse events (TRAEs), including hypomagnesemia, hypocalcemia, and fatigue. No patient experienced grade 5 TRAEs. In the HLX07 combination group, the ORR was 60.0% (18/30), and the median PFS was 7.8 months (95% CI, 3.3 to 9.1). Fourteen (46.7%, 14/30) patients experienced grade 3-4 TRAEs, and one (3.3%, 1/30) patient died due to serplulimab-related pneumonitis.ConclusionsHLX07 monotherapy and its combination with serplulimab and chemotherapy showed manageable toxicity and promising antitumor activity in patients with recurrent or metastatic ESCC. Randomized controlled trials are warranted to further establish the safety and efficacy of HLX07 against ESCC.Trial registrationThis trial was registered at Clinicaltrials.gov (NCT05221658).

BACKGROUND:Gastric cancer is the fifth most common cancer and the fourth most common cause of cancer death worldwide, yet the prognosis of advanced disease remains poor. METHODS:This was a randomized, double-blinded, phase 2 trial (ClinicalTrials.gov: NCT04908813). Patients with locally advanced/metastatic HER2-positive gastric/gastroesophageal junction cancer and no prior systemic antitumor therapy were randomized 1:1:1 to 25 mg/kg HLX22 (a novel anti-HER2 antibody) + HLX02 (trastuzumab biosimilar) + oxaliplatin and capecitabine (XELOX) (group A), 15 mg/kg HLX22 + HLX02 + XELOX (group B), or placebo + HLX02 + XELOX (group C) in 3-week cycles. Primary endpoints were progression-free survival (PFS) and objective response rate (ORR) assessed by independent radiological review committee (IRRC). FINDINGS:Between November 29, 2021, and June 6, 2022, 82 patients were screened; 53 were randomized to group A (n = 18), B (n = 17), and C (n = 18). With 14.3 months of median follow-up, IRRC-assessed median PFS was prolonged with the addition of HLX22 (A vs. C, 15.1 vs. 8.2 months, hazard ratio [HR] 0.5 [95% confidence interval (CI) 0.17-1.27]; B vs. C, not reached vs. 8.2 months, HR 0.1 [95% CI 0.04-0.52]). Confirmed ORR was comparable among groups (A vs. B vs. C, 77.8% vs. 82.4% vs. 88.9%). Treatment-related adverse events (TRAEs) were observed in 18 (100%), 16 (94.1%), and 17 (94.4%) patients, respectively. One (5.6%) patient in group C reported a grade 5 TRAE. CONCLUSIONS:Adding HLX22 to HLX02 and XELOX prolonged PFS and enhanced antitumor response in the first-line treatment of HER2-positive gastric cancer, with manageable safety. FUNDING:Shanghai Henlius Biotech, Inc.

354 Background: Gastric/gastroesophageal junction (G/GEJ) cancer represents a global healthcare challenge. With more than 1 million new cases estimated in 2020, it ranked fifth among all cancers. HER2 amplification or overexpression were reported in around 20% of advanced G/GEJ cancer cases. Despite the improved overall survival with trastuzumab plus chemotherapy, the prognosis remains unsatisfactory, and thus more effective treatments are needed. This study aimed to evaluate the combination of HLX22 (a novel anti-HER2 monoclonal antibody), HLX02 (a trastuzumab biosimilar), and chemotherapy for patients with G/GEJ cancer in the first-line setting. Methods: The study was unblinded 3 months after the last patient was enrolled. Patients with locally advanced or metastatic HER2-positive G/GEJ cancer and had not received prior systemic antitumor therapy were enrolled. The study consisted of 2 parts; current report will focus on part 1. In part 1, patients were randomized 1:1:1 to receive HLX22 25 mg/kg + HLX02 + XELOX (group A), HLX22 15 mg/kg + HLX02 + XELOX (group B), or placebo + HLX02 + XELOX (group C) in 3-week cycles. Primary endpoints were PFS and ORR assessed by IRRC per RECIST v1.1. Secondary endpoints included other efficacy measures and safety. Results: As of July 30, 2023 (data cutoff), 53 patients were randomized to group A (n=18), B (n=17), and C (n=18), and were followed up for a median of 14.3 months. 44 (83.0%) patients were male. Main efficacy results are presented in Table. Tumor assessments reported in Table were performed by IRRC. Treatment-related adverse events (TRAEs) occurred in 18 (100.0%), 16 (94.1%), and 17 (94.4%) patients in the respective groups. Serious TRAEs were observed in 5 (27.8%) patients in group A, 1 (5.9%) in group B, and 1 (5.6%) in group C. Only 1 (5.6%) patient in group C had a grade 5 TRAE. Conclusions: Adding HLX22 to HLX02 + XELOX improved survival and antitumor response in patients with HER2-positive G/GEJ cancer in the first-line setting, with a manageable safety profile. Clinical trial information: NCT04908813 . [Table: see text]

3577 Background: Dual blockade of immune checkpoint and angiogenesis is an effective strategy for multiple cancers. We initiated an open-label, multicenter phase II basket study to evaluate the antitumor activity and safety of camrelizumab (an anti-PD-1 antibody) plus famitinib (a receptor tyrosine kinase inhibitor) in patients (pts) with advanced solid tumors. Herein, we report the results from the metastatic colorectal cancer (mCRC) cohort. Methods: Pts with histologically confirmed mCRC, who had received previous irinotecan, oxaliplatin, and fluoropyrimidine combination chemotherapy, and progressed after ≥ 2 lines of systemic treatment were enrolled to receive camrelizumab (200 mg i.v. every 3 weeks) and famitinib (20 mg orally once daily). Primary endpoint was objective response rate (ORR) per RECIST version 1.1. Results: Between Jul 10, 2020, and Jul 12, 2021, of all the 44 mCRC pts enrolled, 14 (31.8%) pts had colon cancer (CC) and 30 (68.2%) pts had rectal cancer (RC). As of Nov 30, 2021, the median time from enrollment to data cutoff was 10.6 months (range, 4.7-16.7). The ORR was 13.6% (95% CI, 5.2-27.4) and the DCR was 45.5% (95% CI, 30.4-61.2) in all mCRC pts. Of them, no pts with CC achieved response; six pts with RC achieved PR, with the ORR of 20.0% (95% CI, 7.7-38.6) and the DCR of 46.7% (95% CI, 28.3-65.7). Pts with RC showed a median duration of response (DoR) of 7.1 months (95% CI, 2.3-not reached [NR]). The median overall survival (OS) was 15.2 months (95% CI, 7.2-NR) in pts with RC. Of all 44 mCRC pts, 28 (63.6%) had grade 3 or higher treatment related adverse events (TRAEs), mainly hypertension (25.0%), proteinuria (18.2%), decreased platelet count (11.4%), decreased neutrophil count (11.4%) and palmar-plantar erythrodysaesthesia syndrome (11.4%). Three (6.8%) pts discontinued any study treatment due to TRAEs. No grade 5 TRAE was reported. Conclusions: Camrelizumab plus famitinib appeared to show encouraging antitumor activity in pts with mCRC, especially in those with RC, and the safety profile of this combination regimen seemed to be manageable and consistent with single agent alone. Clinical trial information: NCT04346381. [Table: see text]