Hsu, Chih‐Hung

Background and Aims: We compared the safety and efficacy of bintrafusp alfa (BA) in combination with gemcitabine+cisplatin (GemCis), to those of GemCis alone, in patients with biliary tract cancer. Approach and Results: This randomized, double-blind, placebo-controlled, adaptive design phase 2/3 trial (NCT04066491) included adults who are treatment-naive with locally advanced/metastatic biliary tract cancer. Patients (N = 297) were randomized to receive an IV infusion of BA (2400 mg once/3 wk) plus GemCis (gemcitabine 1000 mg/m 2 +cisplatin 25 mg/m 2 on days 1 and 8/3 wk; 8 cycles) (BA group, n = 148) or placebo+GemCis (placebo group, n = 149). The primary end point was overall survival (OS). For adaptation analysis (phase 2-phase 3; data cutoff: May 20, 2021), efficacy was assessed in the first 150 patients who were antibiotic-naive when 80 progression-free survival events had occurred and ≥ 19 weeks of follow-up had been completed (BA, n = 73; placebo, n = 77). Median OS (95% CI) for the BA (11.5 mo [9.3–not estimable]) and placebo (11.5 mo [10.0–not estimable]) groups was comparable (hazard ration 1.23 [95% CI 0.66–2.28]; p = 0.7394); OS data maturity was 27.2% (41 events/151 patients). The most common grade ≥3 treatment-related adverse event was anemia (BA, 26.0%; placebo, 22.8%). Bleeding adverse events were reported more frequently in the BA group (28.8%) versus the placebo group (7.4%). Deaths within 60 days of the first dose were reported in 7.5% and 1.3% of patients in the BA and placebo groups, respectively. Conclusions: BA+GemCis did not provide a clinically meaningful benefit compared with GemCis alone as first-line treatment for biliary tract cancer, and the study was discontinued early (terminated: August 20, 2021).

Abstract Background: Atezolizumab (atezo) and bevacizumab (bev) combination therapy has demonstrated robust clinical activity in patients with unresectable HCC who have not received prior systemic therapy (Lee et al., APPLE 2019; Cheng et al., ESMO Asia 2019). In this exploratory analysis, we aimed to identify tumor-based molecular biomarkers that may be associated with clinical response or resistance to atezo + bev. We also investigated how VEGF blockade with bev could potentiate PD-L1 checkpoint inhibition with atezo in pts with advanced HCC. Methods: Archival tumor tissues or fresh biopsies taken prior to treatment were collected from HCC pts enrolled in the Phase 1b trial GO30140 (NCT02715531). Arm A (n = 104) was a single-arm evaluation of atezo + bev; Arm F (n = 119) was a randomized arm comparing atezo + bev with atezo. Whole-exome sequencing was carried out on these tumor tissues to determine tumor mutation burden (TMB). Gene expression in tumors was profiled by RNAseq analysis. The association between biomarker expression and clinical response (responders [R] vs. non-responders [NR]) or PFS was assessed by t-tests or Cox regression models, respectively. All p-values are descriptive. Results: In Arm A, 90/104 pts were biomarker evaluable. TMB was not associated with response to atezo + bev or PFS. In contrast, analysis of baseline tumor gene expression showed that pre-existing immunity appeared to be associated with clinical response and longer PFS, which included high expression of CD274 (PD-L1) (R vs. NR, p < 2.1 × 10−5; PFS: HR = 0.42 [0.25-0.72]), and T effector signature (GZMB, PRF1, CXCL9) (R vs. NR, p < 0.0004; PFS: HR = 0.46 [0.27-0.78]). Gene expression related to Notch pathway activation (i.e. high expression of HES1) appeared to be associated with lack of response to atezo + bev (p < 0.039) and shorter PFS (HR = 2.1 [1.3-3.6]). In Arm F, 91/119 pts were biomarker evaluable. High expression of VEGF receptor 2 (VEGFR2; HR = 0.36 [0.16-0.81]), Treg (HR = 0.35 [0.15-0.82]), myeloid inflammation (HR = 0.43 [0.19-0.95]), and TREM1/MDSC signatures (HR = 0.43 [0.19-0.94]) was associated with longer PFS in patients treated with atezo + bev than in those treated with atezo alone. Analysis of 12 serial biopsy pairs confirmed reduced levels of VEGFR2 and Treg signatures after atezo + bev treatment. Conclusion: We identified candidate biomarkers for predicting response to atezo + bev in HCC. Furthermore, the findings in Arm F are consistent with previous preclinical studies supporting a multi-faceted role of VEGF/VEGFR signaling in promoting immune suppression in addition to angiogenesis. Overall, the data presented here further support the mechanistic hypotheses on how anti-VEGF may combine with immune checkpoint blockade to increase its clinical benefit. As these results are exploratory, future study is needed to confirm these findings in a larger population. Citation Format: Andrew X. Zhu, Yinghui Guan, Alexander R. Abbas, Hartmut Koeppen, Shan Lu, Chih-Hung Hsu, Kyung-Hun Lee, Michael S. Lee, Aiwu Ruth He, Amit Mahipal, Beiying Ding, Jessica Spahn, Wendy Verret, Baek-Yeol Ryoo, Yulei Wang. Genomic correlates of clinical benefits from atezolizumab combined with bevacizumab vs. atezolizumab alone in patients with advanced hepatocellular carcinoma (HCC) [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT044.

3531 Background: ctDNA has emerged as a promising biomarker for noninvasive monitoring of treatment response and disease progression in many tumor types. However, the clinical use of ctDNA in patients with HCC has not been established. Here, we evaluated longitudinal and personalized detection of ctDNA for monitoring the treatment response to atezolizumab (atezo) + bevacizumab (bev) in patients with unresectable HCC not previously treated with systemic therapy. Methods: A subset (n = 48) of 104 patients with HCC who enrolled in Arm A of GO30140 (NCT02715531; Phase 1b) and received atezo + bev treatment were included in this study. These patients had 10 CR, 11 PR, 12 SD and 15 PD per IRF-assessed RECIST 1.1. Serial plasma samples were collected at baseline (Cycle [C]1 Day [D]1), during treatment (C2D1, C4D1) and at disease progression. Somatic mutations in individual tumors were identified via whole exome sequencing of archival tumor tissues or fresh biopsies collected before treatment. Personalized ctDNA assays (Signatera 16-plex multiplex PCR next-generation sequencing assay) specific to each patient’s tumor mutational signatures were successfully designed for 47 of 48 patients. Results: At C1D1, a median of 25.7 ng of cell-free DNA was extracted from 2-mL plasma samples. ctDNA was detected in 45 of 47 patients (96%), with a median of 70.6 mean tumor molecules/mL of plasma (MTM/mL) and a median of 1.8% mean variant allele frequency (mean VAF) in plasma. Higher ctDNA levels detected at C1D1 appeared to be associated with increased tumor burden ( P < 0.03). Dynamic changes in ctDNA levels post-treatment were associated with response at C4D1. ctDNA status changed from positive at baseline to negative in 7 of 10 CR (70%), 3 of 11 PR (27%), 1 of 11 SD (9%) and 0 of 11 PD (0%) patients. Longer PFS was observed in patients whose ctDNA became undetectable post-treatment. The median PFS in patients with ctDNA present vs cleared at C4D1 was 6.5 months and not reached, respectively (HR, 12 [1.7-93], log-rank P < 0.00029). Conclusions: Our study showed that Signatera, a personalized and tumor-informed ctDNA assay, could be used as a sensitive method for detecting ctDNA in patients with unresectable HCC. More importantly, our results illustrate the promise of ctDNA as an emerging biomarker that may potentially help to monitor treatment responses and disease progression in patients with HCC.