
==== Front
Cancer Immunol Immunother
Cancer Immunol Immunother
Cancer Immunology, Immunotherapy : CII
0340-7004
1432-0851
Springer Berlin Heidelberg Berlin/Heidelberg

39105827
3769
10.1007/s00262-024-03769-4
Research
First-line treatment with KN046, chemotherapy and palliative radiotherapy for advanced esophageal squamous cell carcinoma: an open-label, dose escalation, and dose expansion phase Ib trial
Zhao Qi 1
Su Xi 2
Xue Jiao 1
Liu Yandong 1
Zhu Jiaxing 1
Cai Xuwei birdhome2000@163.com

2
Qin Songbing qin92244@163.com

1
1 https://ror.org/051jg5p78 grid.429222.d 0000 0004 1798 0228 Department of Radiation Oncology, The First Affiliated Hospital of Soochow University, Suzhou, 215000 China
2 grid.16821.3c 0000 0004 0368 8293 Department of Radiation Oncology, Shanghai Chest Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200030 China
6 8 2024
6 8 2024
10 2024
73 10 19413 3 2024
25 6 2024
© The Author(s) 2024
2024
https://creativecommons.org/licenses/by/4.0/ Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
There is growing evidence to suggest that radiotherapy might enhance the efficacy of immunotherapy. This study aimed to assess the possibility of KN046, a bispecific antibody targeting PD-L1 and CTLA-4, combined with chemotherapy and palliative radiotherapy for advanced esophageal squamous cell carcinoma (ESCC). In this open-label, phase Ib trial, patients with advanced ESCC were administered chemotherapy with palliative radiotherapy, and KN046 in the predefined escalation dosages of 1, 3, or 5 mg/kg (every 3 weeks during chemotherapy cycles and every 2 weeks during KN046 maintenance). The chemotherapy regimen constituted cisplatin (75 mg/m2 i.v., d1) and paclitaxel (135–175 mg/m2 ivgtt., d1). Radiotherapy specifics, including site, timing, dose, and fragmentation pattern, were at the investigator’s discretion. The primary outcome was dose-limiting toxicity (DLT). From May 2019 to April 2021, 25 patients were enrolled across the dosage groups: 3 in 1 mg/kg, 12 in 3 mg/kg, and 10 in 5 mg/kg. No DLT was observed during the dose escalation. The objective response rate was 41.7% (95%CI 22.1–63.4), while the disease control rate was 87.5% (95%CI 67.6–97.3). At a median follow-up of 11.8 months, the median progression-free survival was 7.8 months (95%CI 5.2–9.7) and median overall survival was 15.9 months (95%CI 8.4-NE). Serious adverse events were reported in 48.0% of patients, predominantly leukopenia (16%), immune-mediated enterocolitis (12%), immune-mediated pneumonitis (8%), and neutropenia (8%). Combining KN046 with chemotherapy and palliative radiotherapy might be feasible, showing a favorable safety profile and notable efficacy in advanced ESCC patients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00262-024-03769-4.

Keywords

Esophageal squamous cell carcinoma
Chemoradiotherapy
Immune checkpoint inhibitors
Bispecific antibodies
http://dx.doi.org/10.13039/501100001809 National Natural Science Foundation of China K112201720 82073337 Cai Xuwei Qin Songbing Emerging Advanced Technology Joint Research Project of Shanghai Shenkang Hospital Development CenterSHDC12017103 Cai Xuwei Shanghai Municipal Education Commission-Gaofeng Clinical Medicine Grant Support20161433 Cai Xuwei Scientific research project of Suzhou Health TalentsGSWS2020007 Qin Songbing Jiangsu Provincial Medical Key DisciplineZDXK202235 Qin Songbing issue-copyright-statement© Springer-Verlag GmbH Germany, part of Springer Nature 2024
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pmcIntroduction

Efficacious treatment modalities for esophageal squamous cell carcinoma (ESCC) are demanded, since the standard first-line recommendation of 5-fluorouracil and platinum-based chemotherapy have offered limited benefit, often restricting overall survival (OS) to under a year [1]. Robust evidence from the KEYNOTE-590 [2] and CheckMate 648 trials [3] underlined the potency of concomitant administration of immunotherapy with chemotherapy. The CheckMate 648 trial further demonstrated the potential of dual immunotherapy targeting both programmed death ligand-1 (PD-L1) and cytotoxic T lymphocyte-associated protein 4 (CTLA-4) in advanced ESCC [3], as well as in other neoplasms [4, 5].

Radiotherapy has garnered interest in the realm of oncology for its potential synergistic effects with immunotherapy [6, 7]. Central to this hypothesis is the abscopal effect, a principle wherein local radiotherapy elicits systemic anti-tumor responses beyond the irradiated region [8, 9]. Mechanistically, radiotherapy instigates a cascade of cellular events. It augments the systemic liberation of tumor antigens, which are subsequently intercepted by antigen-presenting cells. These cells, in turn, prime and activate T lymphocytes, notably the CD8 cytotoxic subset, inducing a holistic immune offensive against tumor tissues [10]. Notably, radiotherapy modulates the tumor microenvironment, making it more receptive to T cell infiltration, and curtails immunosuppressive signaling pathways [11]. Clinical studies have underscored enhanced therapeutic outcomes when integrating radiotherapy with immune checkpoint inhibitors in non-small cell lung cancer, pancreatic cancer, and head and neck squamous cell carcinoma [12–14].

KN046 emerges as a pioneering humanized bispecific antibody that dually targets PD-L1 and CTLA-4, which has demonstrated a remarkable capacity to potentiate the immune response specifically within the tumor [15–17]. The first-in-human trial of KN046 (KN046-AUS-001) underlined its promising safety metrics, with a solitary case of dose-limiting toxicity (DLT) recorded at a 5.0 mg/kg dose level, administered bi-weekly [18]. Though the combination of immunotherapy and chemotherapy is currently recommended as first-line therapy for advanced ESCC, it was not standard therapeutic option when this study initiated and the benefit of dual immunotherapy is still under investigation. Furthermore, the utilization of immunotherapy to maintain the disease control from chemotherapy and the addition palliative radiotherapy before immunotherapy to enhance the anti-tumor effect was worth exploring. Hence, this phase I trial, characterized by dose-escalation and expansion phases, sought to investigate the possibility of treatment modality of combining standard chemotherapy, palliative radiotherapy, and subsequent KN046 administration in the first-line treatment against advanced ESCC.

Methods

Study design and participants

In this open-label, phase Ib dose-escalation and expansion study, we enrolled patients with advanced ESCC. To qualify for inclusion, participants needed to meet the following primary criteria: they had to be at least 18 years of age; possess a histological confirmation of advanced ESCC with indications for radiotherapy; have not undergone prior systemic treatment for their advanced ESCC condition; and have an Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0–1. Key exclusion criteria encompassed the presence of untreated active cerebral or meningeal metastases; any prior radical radiotherapy carried out within three months before enrollment or palliative radiotherapy within the preceding 2 weeks. A comprehensive list of inclusion and exclusion criteria is documented in Supplementary Table S1.

The study received approval from our Hospital’s Ethics Committee on May 16, 2019, and secured its registration at the Clinical Registry. The study was conducted in accordance with the Declaration of Helsinki, and all participants provided written informed consent before the study’s commencement.

Procedure

In our study, all participants received chemotherapy plus palliative radiotherapy and KN046, as illustrated in Fig. 1. Initially, participants underwent 4–6 chemotherapy cycles (spanning 21 days per cycle) using a regimen of cisplatin (75 mg/m2 i.v., day 1) and paclitaxel (135–175 mg/m2 ivgtt. day 1). The specific number of chemotherapy cycles was tailored to each participant, principally determined by their individual tolerability. During the first to third cycles of chemotherapy, individualized palliative radiotherapy was employed concurrently. In our phase Ib trial, radiation therapy was tailored according to the clinical presentation and history of prior treatment in patients with advanced ESCC: (1) For patients with mediastinal regional recurrence and a previous history of radiotherapy, palliative radiotherapy was administered using conventional fractionation, with total doses ranging from 30 to 40 Gy delivered in 15 to 20 fractions. (2) For patients diagnosed initially with advanced disease who had no history of surgery or radiotherapy, and who presented with regional lymph node involvement or distant metastases, a more intensive regimen was employed. These patients received a total of 50 Gy, delivered in 25 fractions, targeting the primary tumor foci and regional lymph nodes. (3) For patients with non-mediastinal regional recurrence or metastasis, the choice of radiotherapy was guided by patient tolerability. Suitable candidates underwent stereotactic body radiation therapy. For those who could not tolerate SBRT, conventional fractionated radiotherapy was provided, with doses ranging from 30 to 40 Gy delivered in 15 to 20 fractions.Fig. 1 Treatment procedures. Q3W: every 3 weeks. Q2W: every 2 weeks

Subsequent to the palliative radiotherapy, within a 7–14 day window, participants were introduced to the KN046 therapy. The administration was intravenous and dosages were set at predetermined levels of 1, 3, or 5 mg/kg, escalated based on the modified toxicity probability interval (mTPI)-2 method [19]. Throughout the chemotherapy sessions, KN046 was administered at three-week intervals. Once chemotherapy concluded, the administration frequency of KN046 shifted to every two weeks, continuing until any of the following occurred: disease progression, intolerable side effects, voluntary study exit, death, or a treatment duration reaching 108 weeks.

Endpoints

The primary endpoint of this study was DLT, which was assessed within 21 days of the first administration of KN046. DLT evaluation encompassed both hematologic and non-hematologic toxicities, with detailed criteria available in Supplementary Table S1.

Efficacy endpoints included the overall response rate (ORR), disease control rate (DCR), progression-free survival (PFS), and OS. ORR was defined as the proportion of participants achieving complete response (CR) or partial response (PR). DCR was defined as the proportion achieving CR, PR, or stable disease (SD). PFS was the time calculated from enrollment to disease progression or death from any cause, while OS was the time from enrollment to death from any cause. Disease progression was assessed based on Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 criteria. Efficacy evaluations occurred every 6 weeks during the first year of treatment and every 12 weeks thereafter.

Safety endpoints encompassed treatment-emergent adverse events (TEAEs), KN046-related TEAEs, and serious adverse events (SAEs) following the Common Terminology Criteria for Adverse Events of the National Cancer Institute (NCI-CTCAE) Version 5.0. Follow-up visits for TEAEs extended until 30 days after the last KN046 administration or initiation of a new antitumor treatment, whichever came first. SAEs and KN046-related TEAEs were tracked up to 90 days after the last administration.

Stool samples were collected prior to KN046 administration. Metabolomics analysis was performed using liquid chromatography-mass spectrometry (LC–MS) on the Thermo Ultimate 3000 platform equipped with ACQUITY UPLC® HSS T3 1.8 µm columns. The samples were subjected to analysis using an electrospray ionization (ESI) mass analyzer, specifically the Thermo Q Exactive Plus model.

Statistical analysis

Due to the exploratory nature of this study, no hypothesis was tested. The sample size for the dose-escalation phase was determined using the mTPI-2 method. Approximately 20 to 30 patients were planned to be enrolled in the dose expansion phase to capture any additional safety or efficacy signals, although no predefined statistical hypotheses were established. The safety set (SS) consisted of all subjects who received KN046 at least once. The efficacy analysis set (EAS) included all subjects who received KN046 at least once and underwent at least one efficacy evaluation.

PFS and OS rates were calculated using the Kaplan–Meier method. The ORR and DCR were calculated based on the EAS, and their corresponding 95% CIs were calculated using the Clopper-Pearson method. For biomarker analysis, data processing was performed using ProteoWizard (v3.0.8789) and R, followed by matching with the Biodeep’s mass spectrometry database. Short-chain fatty acid (SCFA) data were presented as means ± standard errors. Multivariate data analysis included principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA). To compare metabolites between participants with different treatment responses, the Mann–Whitney-Wilcoxon test was utilized. MetaboAnalyst was employed to conduct metabolic pathway topology analysis of the metabolites. Receiver operating curve (ROC) analysis was performed to assess the potential of treatment response prediction, with the area under the curve (AUC) being calculated. Significant enrichment was indicated by raw P values (RawP) < 0.05 and impact values > 0.

Results

Baseline characteristics of the participants

A total of 25 participants were enrolled in the study, with three cases receiving a dose of 1 mg/kg, 12 participants receiving 3 mg/kg, and 10 participants treated with 5 mg/kg. The median age of the participants was 67.0 years (range: 52–75 years). Among the enrolled participants, 7 (28.0%) had newly diagnosed metastasis disease and 18 (72.0%) had recurrent disease. Besides, 16 patients (64.0%) had a history of prior radiotherapy treatment and 11 patients (44.0%) had undergone prior surgery. Comprehensive baseline characteristics of the participants are provided in Table 1. The data cutoff for the study was April 30, 2021.Table 1 Baseline characteristics of the participants

	All (n = 25)	1 mg/kg (n = 3)	3 mg/kg (n = 12)	5 mg/kg (n = 10)	
Age, years, median (range)	67.0 (52, 75)	67.0 (66, 70)	67.5 (52, 75)	66.0 (61, 73)	
Male, n (%)	19 (76.0)	3 (100.0)	8 (66.7)	8 (80.0)	
ECOG score of 1, n (%)	20 (80.0)	2 (66.7)	8 (66.7)	10 (100.0)	
Disease status at trial entry, n (%)	
Metastatic	7 (28.0)	1 (33.3)	2 (16.7)	4 (40.0)	
Recurrence, locoregional or distant	18 (72.0)	2 (66.7)	10 (83.3)	6 (60.0)	
Recurrence disease (locoregional or distant) at trial entry, n (%)	18	2	10	6	
Mediastinal region only	8 (44.4)	2 (100.0)	4 (40.0)	2 (33.3)	
Mediastinal region and distant metastases	3 (16.7)	0	3 (30.0)	0	
Distant metastases only	7 (38.9)	0	3 (30.0)	4 (66.7)	
Metastatic disease at trial entry, n (%)	7	1	2	4	
Lung	1 (14.3)	0	0	0	
Nonregional lymph	5 (71.4)	1 (100.0)	2 (100.0)	2 (50.0)	
Liver	1 (14.3)	0	0	1 (25.0)	
Prior surgery, n (%)	11 (44)	1 (33.3)	5 (41.7)	5 (50.0)	
Prior radiotherapy, n (%)	16 (64.0)	1 (33.3)	11 (91.7)	4 (40.0)	
Prior chemotherapy, n (%)	16 (64.0)	1 (33.3)	10 (83.3)	5 (50.0)	
ECOG: Eastern cooperative oncology group

Safety

The median duration of KN046 administration varied across the dosage groups: 33.1 weeks (range: 13.7–38.0) for the 1 mg/kg group, 19.8 weeks (range: 3.0–84.0) for the 3 mg/kg group, and 23.3 weeks (range: 3.0–51.0) for the 5 mg/kg group.

No DLTs were observed during the dose escalation phase, and the AEs that occurred during this period are detailed in Supplementary Table S3. Among the 25 enrolled patients, 24 individuals (96%) reported TEAEs. The most prevalent TEAEs included leukopenia (n = 20, 80.0%), neutropenia (n = 16, 64.0%), and nausea (n = 10, 40.0%) as shown in Table 2. The incidence rate of grade ≥ 3 TEAEs was 60% (n = 15), with the most common being leukopenia (n = 13, 52.0%) and neutropenia (n = 12, 48.0%, Table 2).Table 2 Adverse events

	All (n = 25)	1 mg/kg (n = 3)	3 mg/kg (n = 12)	5 mg/kg (n = 10)	
Any grade	Grade ≥ 3	Any grade	Grade ≥ 3	Any grade	Grade ≥ 3	Any grade	Grade ≥ 3	
Any TEAEs	24 (96.0)	15 (60.0)	3 (100.0)	3 (100.0)	12 (100.0)	6 (50.0)	9 (90.0)	6 (60.0)	
KN046-related TEAE	13 (52.0)	4 (16.0)	1 (33.3)	1 (33.3)	6 (50.0)	2 (16.7)	6 (60.0)	1 (10.0)	
SAE	12 (48.0)	3 (100.0)	6 (50.0)	3 (30.0)					
KN046-related SAE	6 (24.0)	1 (33.3)	2 (16.7)	3 (30.0)					
KN046-related treatment discontinuation	4 (16.0)	1 (33.3)	2 (16.7)	1 (10.0)					
Most common TEAEs	
Leukopenia	20 (80.0)	13 (52.0)	3 (100.0)	2 (66.7)	9 (75.0)	5 (41.7)	8 (80.0)	6 (60.0)	
Neutropenia	16 (64.0)	12 (48.0)	3 (100.0)	3 (100.0)	7 (58.3)	5 (41.7)	6 (60.0)	4 (40.0)	
Nausea	10 (40.0)	0	3 (100.0)	0	5 (41.7)	0	2 (20.0)	0	
Thrombocytopenia	9 (36.0)	0	2 (66.7)	0	3 (25.0)	0	4 (40.0)	0	
Cough	8 (32.0)	0	1 (33.3)	0	5 (41.7)	0	2 (20.0)	0	
Decreased appetite	8 (32.0)	0	1 (33.3)	0	5 (41.7)	0	2 (20.0)	0	
Most common KN046-related TEAE	
Pruritus	4 (16.0)	0	0	0	2 (16.7)	0	2 (20.0)	0	
Immune-mediated enterocolitis	3 (12.0)	2 (8.0)	1 (33.3)	1 (33.3)	1 (8.3)	1 (8.3)	1 (10.0)	0	
Rash	3 (12.0)	0	0	0	1 (8.3)	0	2 (20.0)	0	
Dermatitis allergic	2 (8.0)	0	0	0	1 (8.3)	0	1 (10.0)	0	
Immune-mediated pneumonitis	2 (8.0)	1 (4.0)	0	0	2 (16.7)	1 (8.3)	0	0	
Infusion related reaction	2 (8.0)	0	0	0	1 (8.3)	0	1 (10.0)	0	
Most common SAEs	
Leukopenia	4 (16.0)	0	3 (25.0)	1 (10.0)					
Immune-mediated enterocolitis	3 (12.0)	1 (33.3)	1 (8.3)	1 (10.0)					
Immune-mediated pneumonitis	2 (8.0)	2 (66.7)	0	0					
Neutropenia	2 (8.0)	1 (33.3)	1 (8.3)	0					
Most common KN046-related SAE	
Immune-mediated enterocolitis	3 (12.0)	1 (33.3)	1 (8.3)	1 (10.0)					
Immune-mediated pneumonitis	2 (8.0)	0	2 (16.7)	0					
Immune-mediated hepatitis	1 (4.0)	0	0	1 (10.0)					
Rash	1 (4.0)	0	0	1 (10.0)					
All data were presented as n (%)

TEAE, treatment-emergent adverse events; SAE, serious adverse event

SAEs were encountered by 12 participants (48%). The leading SAEs included leukopenia (n = 4, 16%), immune-mediated enterocolitis (n = 3, 12%), immune-mediated pneumonitis (n = 2, 8%), and neutropenia (n = 2, 8%). The incidence rate of KN046-related SAEs was 24.0% (n = 6), with immune-mediated enterocolitis (n = 3, 12%) and immune-mediated pneumonitis (n = 2, 8%) being the most prevalent. A total of four participants (16.0%) had to discontinue treatment due to KN046-related TEAEs, which included two cases of immune-mediated enterocolitis, one case of immune-mediated pneumonitis, and one case of immune-mediated hepatitis.

Efficacy

One participant in the 5 mg/kg group could not be evaluated for efficacy since they did not receive KN046 after completing only one cycle of chemotherapy due to intolerability. The treatment response is illustrated in Fig. 2. Three participants achieved CR, and seven achieved confirmed PR, resulting in an ORR of 41.7% (95% CI 22.1%-63.4%). The DCR was 87.5% (95% CI 67.6%-97.3%), as shown in Table 3.Fig. 2 Swimming lane plot of treatment response. CR: complete response; PR: partial response; SD: stable disease; PD: progressive disease; NE: non-evaluable

Table 3 Efficacy

	All (n = 24)	1 mg/kg (n = 3)	3 mg/kg (n = 12)	5 mg/kg (n = 9)	
ORR	41.7 (22.1–63.4)	33.3 (0.8–90.6)	58.3 (27.7–84.8)	22.2 (2.8–60.0)	
DCR	87.5 (67.6–97.3)	66.7 (9.4–99.2)	100.0 (73.5–100.0)	77.8 (40.0–97.2)	
CBR	58.3 (36.6–77.9)	33.3 (0.8–90.6)	75.0 (42.8, 94.5)	44.4 (13.7–78.8)	
Median PFS	7.8 (5.2, 9.7)	5.2 (1.2, NE)	NE (5.6, NE)	5.6 (2.6, 8.3)	
6 month PFS rate	57.0 (33.2, 75.1)	33.3 (0.9, 77.4)	80.8 (42.3–94.9)	31.1 (4.6–64.1)	
9 month PFS rate	34.2 (14.5, 55.1)	0	57.7 (22.1, 81.9)	15.6 (0.8, 49.1)	
12 month PFS rate	28.5 (10.7, 49.5)	0	57.7 (22.1, 81.9)	0 (NE, NE)	
Median OS	15.9 (8.4, NE)	11.1 (5.2, NE)	NE (7.2, NE)	NE (5.0, NE)	
6 month OS rate	87.1 (64.9, 95.6)	66.7 (5.4, 94.5)	91.7 (53.9, 98.8)	87.5 (38.7, 98.1)	
9 month OS rate	73.3 (49.9, 87.1)	66.7 (5.4, 94.5)	75.0 (40.8, 91.2)	72.9 (27.6, 92.5)	
12 month OS rate	66.6 (41.6, 82.9)	33.3 (0.9, 77.4)	75.0 (40.8, 91.2)	72.9 (27.6, 92.5)	
All data were presented as % (95% CI), except for median PFS and OS (months, 95%CI)

ORR, objective response rate; DCR, disease control rate; CBR, clinical benefit rate; PFS, progression-free survival; OS, overall survival; NE, non-evaluable

The median follow-up was 11.8 months (range: 9.3–15.6). In the entire participant cohort, the median PFS was 7.8 months (95% CI 5.2–9.7) (Fig. 3A). This included specific median PFS durations of 5.2 months (95% CI 1.2-not estimated [NE]), NE (95% CI 5.6-NE), and 5.6 months (95% CI 2.6–8.3) for the 1, 3, and 5 mg/kg dose groups, respectively. The 6 and 12 month PFS rates were 57.0% (95% CI 33.2–75.1) and 28.5% (95% CI 10.7–49.5), respectively (Table 3). Regarding OS, the median OS for all participants was 15.9 months (95% CI 8.4-NE), as shown in Fig. 3B. This encompassed specific median OS durations of 11.1 months (95% CI 5.2-NE), NE (95% CI 7.2-NE), and NE (95% CI: 5.0-NE) for the 1, 3, and 5 mg/kg dose groups, respectively. The 6 and 12 month OS rates were 87.1% (95% CI 64.9–95.6) and 66.6% (95% CI 41.6–82.9) for all participants, respectively (Fig. 3B, Table 3).Fig. 3 Progression-free survival A and overall survival B. NE: non-evaluable

Biomarker analysis

Biomarker analysis samples were available from 11 participants, comprising five with SD and six with PR. The application of PCA and OPLS-DA revealed distinct metabolite clustering patterns between participants exhibiting PR and SD (Supplementary Figure S1A-B). This clustering was particularly evident in participants with PR. In terms of differentially expressed metabolites, there were 36 upregulated and 110 downregulated metabolites in participants with PR compared to those with SD (Supplementary Figure S2A). Notably, levels of SCFA including butyric, acetic, and valeric acid were significantly lower in participants with SD than in those with PR (all rawP < 0.01, Impact > 0, Supplementary Figure S2B). Metabolic pathway topology analysis highlighted the enrichment of propanoic and acetic acid. Furthermore, acetic acid emerged as a potential predictor of treatment response, displaying an AUC of 0.933 (95% CI 0.733–1) (Supplementary Figure S2C).

Discussion

In the rapidly evolving landscape of immunotherapy, the emergence of dual-targeting immune checkpoint inhibitors has presented promising therapeutic avenues. These novel agents have consistently demonstrated a relatively benign safety profile, often comparable to their single-target antibody counterparts. Recent data from a phase I trial examining m7824, a bispecific agent targeting PD-L1 and TGFΒ in advanced solid tumors, revealed TRAEs of grade ≥ 3 in 21.1% of participants, encompassing conditions such as skin infections, asymptomatic lipase elevation, colitis coupled with anemia, and gastroparesis accompanied by hypokalemia [20]. Another trial involving Bintrafusp alfa, a PD-L1/TGFΒ fusion protein, in ESCC yielded TRAEs in 63.3% of participants, with 23.3% experiencing grade ≥ 3 events [21]. Our current investigation revealed an encouraging safety profile for KN046. During the dose-escalation phase, no DLT events were detected. Moreover, the incidence of grade ≥ 3 KN046-associated TEAEs was observed at 16.0%, lower than reports from other studies involving the combination of nivolumab and ipilimumab [3]. These results suggested the advantage of bispecific antibodies, like KN046, over combinations of two monoclonal antibodies. This incidence also aligns favorably with data from single-target anti-PD-L1 antibodies [22], indicating that AEs associated with KN046 remain manageable in the context of ESCC. Of particular note, the reported incidences of KN046-related SAEs and treatment discontinuations in our study, 24% and 16.0% respectively, mirror findings from prior studies on dual checkpoint inhibitors [20, 21]. It's also worth emphasizing that the integration of KN046 did not elicit unexpected safety concerns when juxtaposed against the safety profile of chemotherapy plus radiotherapy for advanced ESCC [23].

The synergy between radiotherapy and immunotherapy is of pivotal importance in contemporary oncologic research [6, 7]. Central to this hypothesis is the abscopal effect, wherein local radiotherapy induces systemic anti-cancer responses beyond the irradiated field [8, 9]. Radiotherapy likely boosts the systemic release of tumor-associated antigens, subsequently taken up by antigen-presenting cells and presented to CD8 cytotoxic T lymphocytes, culminating in a systemic anti-tumor response [10]. Moreover, radiotherapy may modulate the tumor microenvironment to be more receptive to T cell infiltration, reducing inhibitory signals like transforming growth factor β and thereby making the tumor more susceptible to immune cells [24, 25]. Clinically, this promise is being realized. In metastatic non-small-cell lung cancer, integrating pembrolizumab immunotherapy with radiotherapy significantly improved patient outcomes [12]. Likewise, the a phase 2 trial combining stereotactic body radiotherapy with pembrolizumab and trametinib emerged as a promising approach for recurrent post-surgery pancreatic cancer patients [13]. Our study sought to extend this investigation to the context of ESCC, combining chemotherapy, palliative radiotherapy, and subsequent administration of KN046.

At the outset of this study, first-line treatments for ESCC did not predominantly include immunotherapy-chemotherapy combinations or dual immunotherapy. Our exploration into combining KN046 with chemotherapy and palliative radiotherapy addressed a pressing need to identify more efficacious treatments for advanced ESCC. Since our study’s inception, both strategies have been approved as frontline treatments, underscoring the fast-evolving nature of oncological interventions. The pivotal trials such as KEYNOTE-590 [2] and CheckMate 648 [3] have underscored the benefits of adding agents like pembrolizumab or nivolumab to chemotherapy for patients with advanced ESCC. A median PFS of approximately 6 months and a median OS of around 13 months were observed. Another phase II trial juxtaposing camrelizumab with apatinib and chemotherapy revealed a median PFS of 6.85 months and a median OS of 19.43 months [26], thereby emphasizing the viability of immunotherapy combinations. Concurrently, the CheckMate 648 trial discerned the benefits of nivolumab and ipilimumab in prolonging the OS of patients with advanced ESCC, although no PFS benefits were noted in comparison to chemotherapy alone [3]. Our findings, revealing a median PFS and OS of 7.8 and 15.9 months respectively, suggest that KN046 holds comparable efficacy to other immunotherapy regimens, even those harnessing dual immunotherapeutic agents, in advanced ESCC. Moreover, our research postulates that palliative radiotherapy might further bolster the efficacy of immune checkpoint inhibitors, given its potential influence on the tumor microenvironment. This assertion was also evidenced by previous trials involving camrelizumab plus radiotherapy [27], camrelizumab plus chemoradiotherapy [28], atezolizumab plus chemoradiotherapy [29] and sintilimab plus chemoradiotherapy [30] in esophageal cancers. While the disparities due to study population heterogeneity might exist, the precise role of radiotherapy in augmenting the action of immune checkpoint inhibitors warrants further exploration in subsequent studies.

The relationship between the gut metabolome and the efficacy of immunotherapy remains a subject of ongoing discussion. Metabolites like SCFAs play a crucial role in mediating interactions among diet, microbiota, and the host. Emerging evidence has indicated links between SCFAs and treatment responses to pembrolizumab and nivolumab, as well as prognoses in patients with solid tumors [31]. SCFAs affect the CD4+ T cells, with butyric acid being able to induce FOXP3+ CD4+ Tregs differentiation [32–34]. SCFAs can also inhibit histone deacytelases [35–37], which inhibit CD4+ T cell apoptosis, upregulate antitumor immune response, and suppress tumor growth [38–40]. Gut-derived SCFAs influence the tumor response and the occurrence of AEs [41]. In this study, discernible differences in SCFA levels were observed between patients with SD and PR, particularly in the case of acetic acid, which could potentially serve as a predictive marker for treatment response. It's worth noting, however, that the sample size for gut metabolome and microbiota analysis was relatively modest. Given the variations in racial backgrounds, dietary habits, and cultural factors, further research into the relationship between the gut metabolome, microbiota, and treatment responses is warranted.

Our study, being a phase I trial, inherently bears certain limitations. Principally, the limited sample size restricts our capacity to draw statistically significant conclusions. The data on efficacy, while encouraging, remains preliminary, with the study's short-term follow-up serving as an additional constraint in its interpretability. The absence of comparator groups further inhibits our ability to make robust comparisons of the therapeutic efficacy and safety of KN046. In addition, the individualized radiotherapy protocol might produce certain bias when interpreting the abscopal effect of radiotherapy. Due to the exploratory nature and small sample size of this phase Ib trial, comprehensive biomarker analyses including tissue-derived or blood-derived markers such as PD-L1 were not conducted. It is imperative, hence, that subsequent investigations expand upon these findings through head-to-head studies, encompassing larger patient cohorts and extended follow-up periods to circumvent the aforementioned limitations.

In this phase I trial, the combination of KN046, a dual immune checkpoint inhibitor targeting PD-L1 and CTLA-4, with chemotherapy and palliative radiotherapy has shown feasibility for patients with advanced ESCC, exhibiting a commendable safety profile. Intriguingly, our findings also hint at the potential role of the gut’s metabolomic and microbiotic profile as predictive markers for treatment response.

Supplementary Information

Below is the link to the electronic supplementary material.Supplementary file1 (DOCX 467 KB)

Acknowledgements

We thanked all patients for the participating in this trial and Alphamab Oncology for providing the study drugs. We also acknowledge Jia Wang and Baohong Guo for their support with manuscript revision.

Author contributions

Songbing Qin and Xuwei Cai: design of clinical studies, guidance during execution. Qi Zhao, Jiao Xue, Yandong Liu, and Jiaxing Zhu: enrollment, treatment, and follow-up. Xi Su: data collection and statistics. Qi Zhao and Xi Su: writing, reviewing, and editing.

Funding

This work was supported in part by the National Natural Science Foundation of China (grant number: K112201720; 82073337), the Scientific research project of Suzhou Health Talents (grant number: GSWS2020007), the Emerging Advanced Technology Joint Research Project of Shanghai Shenkang Hospital Development Center (grant no. SHDC12017103), Jiangsu Provincial Medical Key Discipline (grant number: ZDXK202235) and the Shanghai Municipal Education Commission-Gaofeng Clinical Medicine Grant Support (grant no. 20161433).

Data availability

All data relevant to the study are included in the article or uploaded as supplementary information.

Declarations

Conflict of interest

The authors have no relevant financial or non-financial interests to disclose.

Ethical approval

The study was conducted in accordance with the Declaration of Helsinki and received approval from our Hospital's Ethics Committee on May 16, 2019, and secured its registration at the Clinical Registry.

Consent to participate

All participants provided written informed consent before the study’s commencement.

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Qi Zhao and Xi Su have contributed equally to this work.
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References

1. Hirata H Niida A Kakiuchi N Uchi R Sugimachi K Masuda T The evolving genomic landscape of esophageal squamous cell carcinoma under chemoradiotherapy Cancer Res 2021 81 4926 4938 10.1158/0008-5472.can-21-0653 34413060
Hirata H, Niida A, Kakiuchi N, Uchi R, Sugimachi K, Masuda T et al (2021) The evolving genomic landscape of esophageal squamous cell carcinoma under chemoradiotherapy. Cancer Res 81:4926–4938. 10.1158/0008-5472.can-21-065334413060 10.1158/0008-5472.can-21-0653
2. Sun J-M Shen L Shah MA Enzinger P Adenis A Doi T Pembrolizumab plus chemotherapy versus chemotherapy alone for first-line treatment of advanced oesophageal cancer (KEYNOTE-590): a randomised, placebo-controlled, phase 3 study The Lancet 2021 398 759 771 10.1016/s0140-6736(21)01234-4
Sun J-M, Shen L, Shah MA, Enzinger P, Adenis A, Doi T et al (2021) Pembrolizumab plus chemotherapy versus chemotherapy alone for first-line treatment of advanced oesophageal cancer (KEYNOTE-590): a randomised, placebo-controlled, phase 3 study. The Lancet 398:759–771. 10.1016/s0140-6736(21)01234-410.1016/s0140-6736(21)01234-4
3. Doki Y Ajani JA Kato K Xu J Wyrwicz L Motoyama S Nivolumab combination therapy in advanced esophageal squamous-cell carcinoma N Engl J Med 2022 386 449 462 10.1056/NEJMoa2111380 35108470
Doki Y, Ajani JA, Kato K, Xu J, Wyrwicz L, Motoyama S et al (2022) Nivolumab combination therapy in advanced esophageal squamous-cell carcinoma. N Engl J Med 386:449–462. 10.1056/NEJMoa211138035108470 10.1056/NEJMoa2111380
4. Gao J Navai N Alhalabi O Siefker-Radtke A Campbell MT Tidwell RS Neoadjuvant PD-L1 plus CTLA-4 blockade in patients with cisplatin-ineligible operable high-risk urothelial carcinoma Nat Med 2020 26 1845 1851 10.1038/s41591-020-1086-y 33046869
Gao J, Navai N, Alhalabi O, Siefker-Radtke A, Campbell MT, Tidwell RS et al (2020) Neoadjuvant PD-L1 plus CTLA-4 blockade in patients with cisplatin-ineligible operable high-risk urothelial carcinoma. Nat Med 26:1845–1851. 10.1038/s41591-020-1086-y33046869 10.1038/s41591-020-1086-y
5. Perets R Bar J Rasco DW Ahn MJ Yoh K Kim DW Safety and efficacy of quavonlimab, a novel anti-CTLA-4 antibody (MK-1308), in combination with pembrolizumab in first-line advanced non-small-cell lung cancer Ann Oncol 2021 32 395 403 10.1016/j.annonc.2020.11.020 33276076
Perets R, Bar J, Rasco DW, Ahn MJ, Yoh K, Kim DW et al (2021) Safety and efficacy of quavonlimab, a novel anti-CTLA-4 antibody (MK-1308), in combination with pembrolizumab in first-line advanced non-small-cell lung cancer. Ann Oncol 32:395–403. 10.1016/j.annonc.2020.11.02033276076 10.1016/j.annonc.2020.11.020
6. McLaughlin M Patin EC Pedersen M Wilkins A Dillon MT Melcher AA Inflammatory microenvironment remodelling by tumour cells after radiotherapy Nat Rev Cancer 2020 20 203 217 10.1038/s41568-020-0246-1 32161398
McLaughlin M, Patin EC, Pedersen M, Wilkins A, Dillon MT, Melcher AA et al (2020) Inflammatory microenvironment remodelling by tumour cells after radiotherapy. Nat Rev Cancer 20:203–217. 10.1038/s41568-020-0246-132161398 10.1038/s41568-020-0246-1
7. Formenti SC Rudqvist NP Golden E Cooper B Wennerberg E Lhuillier C Radiotherapy induces responses of lung cancer to CTLA-4 blockade Nat Med 2018 24 1845 1851 10.1038/s41591-018-0232-2 30397353
Formenti SC, Rudqvist NP, Golden E, Cooper B, Wennerberg E, Lhuillier C et al (2018) Radiotherapy induces responses of lung cancer to CTLA-4 blockade. Nat Med 24:1845–1851. 10.1038/s41591-018-0232-230397353 10.1038/s41591-018-0232-2
8. Deng L Liang H Xu M Yang X Burnette B Arina A STING-dependent cytosolic dna sensing promotes radiation-induced type I interferon-dependent antitumor immunity in immunogenic tumors Immunity 2014 41 843 852 10.1016/j.immuni.2014.10.019 25517616
Deng L, Liang H, Xu M, Yang X, Burnette B, Arina A et al (2014) STING-dependent cytosolic dna sensing promotes radiation-induced type I interferon-dependent antitumor immunity in immunogenic tumors. Immunity 41:843–852. 10.1016/j.immuni.2014.10.01925517616 10.1016/j.immuni.2014.10.019
9. Vanpouille-Box C Demaria S Formenti SC Galluzzi L Cytosolic DNA sensing in organismal tumor control Cancer Cell 2018 34 361 378 10.1016/j.ccell.2018.05.013 30216189
Vanpouille-Box C, Demaria S, Formenti SC, Galluzzi L (2018) Cytosolic DNA sensing in organismal tumor control. Cancer Cell 34:361–378. 10.1016/j.ccell.2018.05.01330216189 10.1016/j.ccell.2018.05.013
10. Menon H Chen D Ramapriyan R Verma V Barsoumian HB Cushman TR Influence of low-dose radiation on abscopal responses in patients receiving high-dose radiation and immunotherapy J Immunother Cancer 2019 7 237 10.1186/s40425-019-0718-6 31484556
Menon H, Chen D, Ramapriyan R, Verma V, Barsoumian HB, Cushman TR et al (2019) Influence of low-dose radiation on abscopal responses in patients receiving high-dose radiation and immunotherapy. J Immunother Cancer 7:237. 10.1186/s40425-019-0718-631484556 10.1186/s40425-019-0718-6
11. Menon H Ramapriyan R Cushman TR Verma V Kim HH Schoenhals JE Role of radiation therapy in modulation of the tumor stroma and microenvironment Front Immunol 2019 10 193 10.3389/fimmu.2019.00193 30828330
Menon H, Ramapriyan R, Cushman TR, Verma V, Kim HH, Schoenhals JE et al (2019) Role of radiation therapy in modulation of the tumor stroma and microenvironment. Front Immunol 10:193. 10.3389/fimmu.2019.0019330828330 10.3389/fimmu.2019.00193
12. Theelen WSME Chen D Verma V Hobbs BP Peulen HMU Aerts JGJV Pembrolizumab with or without radiotherapy for metastatic non-small-cell lung cancer: a pooled analysis of two randomised trials Lancet Respir Med 2021 9 467 475 10.1016/s2213-2600(20)30391-x 33096027
Theelen WSME, Chen D, Verma V, Hobbs BP, Peulen HMU, Aerts JGJV et al (2021) Pembrolizumab with or without radiotherapy for metastatic non-small-cell lung cancer: a pooled analysis of two randomised trials. Lancet Respir Med 9:467–475. 10.1016/s2213-2600(20)30391-x33096027 10.1016/s2213-2600(20)30391-x
13. Zhu X Cao Y Liu W Ju X Zhao X Jiang L Stereotactic body radiotherapy plus pembrolizumab and trametinib versus stereotactic body radiotherapy plus gemcitabine for locally recurrent pancreatic cancer after surgical resection: an open-label, randomised, controlled, phase 2 trial Lancet Oncol 2021 22 1093 1102 10.1016/s1470-2045(21)00286-2 34237249
Zhu X, Cao Y, Liu W, Ju X, Zhao X, Jiang L et al (2021) Stereotactic body radiotherapy plus pembrolizumab and trametinib versus stereotactic body radiotherapy plus gemcitabine for locally recurrent pancreatic cancer after surgical resection: an open-label, randomised, controlled, phase 2 trial. Lancet Oncol 22:1093–1102. 10.1016/s1470-2045(21)00286-234237249 10.1016/s1470-2045(21)00286-2
14. McBride S Sherman E Tsai CJ Baxi S Aghalar J Eng J Randomized phase II trial of nivolumab with stereotactic body radiotherapy versus nivolumab alone in metastatic head and neck squamous cell carcinoma J Clin Oncol 2021 39 30 37 10.1200/JCO.20.00290 32822275
McBride S, Sherman E, Tsai CJ, Baxi S, Aghalar J, Eng J et al (2021) Randomized phase II trial of nivolumab with stereotactic body radiotherapy versus nivolumab alone in metastatic head and neck squamous cell carcinoma. J Clin Oncol 39:30–37. 10.1200/JCO.20.0029032822275 10.1200/JCO.20.00290
15. Zhao Y Lee CK Lin CH Gassen RB Xu X Huang Z PD-L1:CD80 Cis-heterodimer triggers the Co-stimulatory receptor CD28 while repressing the inhibitory PD-1 and CTLA-4 pathways Immunity 2019 10.1016/j.immuni.2019.11.003 31882362
Zhao Y, Lee CK, Lin CH, Gassen RB, Xu X, Huang Z et al (2019) PD-L1:CD80 Cis-heterodimer triggers the Co-stimulatory receptor CD28 while repressing the inhibitory PD-1 and CTLA-4 pathways. Immunity. 10.1016/j.immuni.2019.11.00331882362 10.1016/j.immuni.2019.11.003
16. Sugiura D Maruhashi T Okazaki IM Shimizu K Maeda TK Takemoto T Restriction of PD-1 function by cis-PD-L1/CD80 interactions is required for optimal T cell responses Science 2019 364 558 566 10.1126/science.aav7062 31000591
Sugiura D, Maruhashi T, Okazaki IM, Shimizu K, Maeda TK, Takemoto T et al (2019) Restriction of PD-1 function by cis-PD-L1/CD80 interactions is required for optimal T cell responses. Science 364:558–566. 10.1126/science.aav706231000591 10.1126/science.aav7062
17. Mayoux M Roller A Pulko V Sammicheli S Chen S Sum E Dendritic cells dictate responses to PD-L1 blockade cancer immunotherapy Sci Transl Med 2020 10.1126/scitranslmed.aav7431 32161104
Mayoux M, Roller A, Pulko V, Sammicheli S, Chen S, Sum E et al (2020) Dendritic cells dictate responses to PD-L1 blockade cancer immunotherapy. Sci Transl Med. 10.1126/scitranslmed.aav743132161104 10.1126/scitranslmed.aav7431
18. Coward J Ganju V Behzadigohar R Kwong K Xu J Van H Preliminary safety, efficacy, and pharmacokinetics (PK) results of KN046 (bispecific anti-PD-L1/CTLA4) from a first-in-human study in subjects with advanced solid tumors J Clin Oncol 2019 37 2554 10.1200/JCO.2019.37.15_suppl.2554
Coward J, Ganju V, Behzadigohar R, Kwong K, Xu J, Van H et al (2019) Preliminary safety, efficacy, and pharmacokinetics (PK) results of KN046 (bispecific anti-PD-L1/CTLA4) from a first-in-human study in subjects with advanced solid tumors. J Clin Oncol 37:2554. 10.1200/JCO.2019.37.15_suppl.255410.1200/JCO.2019.37.15_suppl.2554
19. Guo W Wang SJ Yang S Lynn H Ji Y A bayesian interval dose-finding design addressingOckham’s razor: mTPI-2 Contemp Clin Trials 2017 58 23 33 10.1016/j.cct.2017.04.006 28458054
Guo W, Wang SJ, Yang S, Lynn H, Ji Y (2017) A bayesian interval dose-finding design addressingOckham’s razor: mTPI-2. Contemp Clin Trials 58:23–33. 10.1016/j.cct.2017.04.00628458054 10.1016/j.cct.2017.04.006
20. Strauss J Heery CR Schlom J Madan RA Cao L Kang Z Phase I Trial of M7824 (MSB0011359C), a bifunctional fusion protein targeting PD-L1 and TGFbeta, in advanced solid tumors Clin Cancer Res 2018 24 1287 1295 10.1158/1078-0432.CCR-17-2653 29298798
Strauss J, Heery CR, Schlom J, Madan RA, Cao L, Kang Z et al (2018) Phase I Trial of M7824 (MSB0011359C), a bifunctional fusion protein targeting PD-L1 and TGFbeta, in advanced solid tumors. Clin Cancer Res 24:1287–1295. 10.1158/1078-0432.CCR-17-265329298798 10.1158/1078-0432.CCR-17-2653
21. Lin CC Doi T Muro K Hou MM Esaki T Hara H Bintrafusp alfa, a bifunctional fusion protein targeting TGFbeta and PD-L1, in patients with esophageal squamous cell carcinoma: results from a phase 1 cohort in asia Target Oncol 2021 16 447 459 10.1007/s11523-021-00810-9 33840050
Lin CC, Doi T, Muro K, Hou MM, Esaki T, Hara H et al (2021) Bintrafusp alfa, a bifunctional fusion protein targeting TGFbeta and PD-L1, in patients with esophageal squamous cell carcinoma: results from a phase 1 cohort in asia. Target Oncol 16:447–459. 10.1007/s11523-021-00810-933840050 10.1007/s11523-021-00810-9
22. Baba Y Nomoto D Okadome K Ishimoto T Iwatsuki M Miyamoto Y Tumor immune microenvironment and immune checkpoint inhibitors in esophageal squamous cell carcinoma Cancer Sci 2020 111 3132 3141 10.1111/cas.14541 32579769
Baba Y, Nomoto D, Okadome K, Ishimoto T, Iwatsuki M, Miyamoto Y et al (2020) Tumor immune microenvironment and immune checkpoint inhibitors in esophageal squamous cell carcinoma. Cancer Sci 111:3132–3141. 10.1111/cas.1454132579769 10.1111/cas.14541
23. Chao M Wu H Jin K Li B Wu J Zhang G A nonrandomized cohort and a randomized study of local control of large hepatocarcinoma by targeting intratumoral lactic acidosis Elife 2016 10.7554/eLife.15691 27481188
Chao M, Wu H, Jin K, Li B, Wu J, Zhang G et al (2016) A nonrandomized cohort and a randomized study of local control of large hepatocarcinoma by targeting intratumoral lactic acidosis. Elife. 10.7554/eLife.1569127481188 10.7554/eLife.15691
24. Vanpouille-Box C Diamond JM Pilones KA Zavadil J Babb JS Formenti SC TGFbeta is a master regulator of radiation therapy-induced antitumor immunity Cancer Res 2015 75 2232 2242 10.1158/0008-5472.CAN-14-3511 25858148
Vanpouille-Box C, Diamond JM, Pilones KA, Zavadil J, Babb JS, Formenti SC et al (2015) TGFbeta is a master regulator of radiation therapy-induced antitumor immunity. Cancer Res 75:2232–2242. 10.1158/0008-5472.CAN-14-351125858148 10.1158/0008-5472.CAN-14-3511
25. Klug F Prakash H Huber PE Seibel T Bender N Halama N Low-dose irradiation programs macrophage differentiation to an iNOS(+)/M1 phenotype that orchestrates effective T cell immunotherapy Cancer Cell 2013 24 589 602 10.1016/j.ccr.2013.09.014 24209604
Klug F, Prakash H, Huber PE, Seibel T, Bender N, Halama N et al (2013) Low-dose irradiation programs macrophage differentiation to an iNOS(+)/M1 phenotype that orchestrates effective T cell immunotherapy. Cancer Cell 24:589–602. 10.1016/j.ccr.2013.09.01424209604 10.1016/j.ccr.2013.09.014
26. Zhang B Qi L Wang X Xu J Liu Y Mu L Phase II clinical trial using camrelizumab combined with apatinib and chemotherapy as the first-line treatment of advanced esophageal squamous cell carcinoma Cancer Commun (Lond) 2020 40 711 720 10.1002/cac2.12119 33314747
Zhang B, Qi L, Wang X, Xu J, Liu Y, Mu L et al (2020) Phase II clinical trial using camrelizumab combined with apatinib and chemotherapy as the first-line treatment of advanced esophageal squamous cell carcinoma. Cancer Commun (Lond) 40:711–720. 10.1002/cac2.1211933314747 10.1002/cac2.12119
27. Zhang W Yan C Gao X Li X Cao F Zhao G Safety and feasibility of radiotherapy plus camrelizumab for locally advanced esophageal squamous cell carcinoma Oncologist 2021 26 e1110 e1124 10.1002/onco.13797 33893689
Zhang W, Yan C, Gao X, Li X, Cao F, Zhao G et al (2021) Safety and feasibility of radiotherapy plus camrelizumab for locally advanced esophageal squamous cell carcinoma. Oncologist 26:e1110–e1124. 10.1002/onco.1379733893689 10.1002/onco.13797
28. Zhang W Yan C Zhang T Chen X Dong J Zhao J Addition of camrelizumab to docetaxel, cisplatin, and radiation therapy in patients with locally advanced esophageal squamous cell carcinoma: a phase 1b study Oncoimmunology 2021 10 1971418 10.1080/2162402X.2021.1971418 34616588
Zhang W, Yan C, Zhang T, Chen X, Dong J, Zhao J et al (2021) Addition of camrelizumab to docetaxel, cisplatin, and radiation therapy in patients with locally advanced esophageal squamous cell carcinoma: a phase 1b study. Oncoimmunology 10:1971418. 10.1080/2162402X.2021.197141834616588 10.1080/2162402X.2021.1971418
29. van den Ende T de Clercq NC van Berge Henegouwen MI Gisbertz SS Geijsen ED Verhoeven RHA Neoadjuvant chemoradiotherapy combined with atezolizumab for resectable esophageal adenocarcinoma: a single-arm phase II feasibility trial (PERFECT) Clin Cancer Res 2021 27 3351 3359 10.1158/1078-0432.CCR-20-4443 33504550
van den Ende T, de Clercq NC, van Berge Henegouwen MI, Gisbertz SS, Geijsen ED, Verhoeven RHA et al (2021) Neoadjuvant chemoradiotherapy combined with atezolizumab for resectable esophageal adenocarcinoma: a single-arm phase II feasibility trial (PERFECT). Clin Cancer Res 27:3351–3359. 10.1158/1078-0432.CCR-20-444333504550 10.1158/1078-0432.CCR-20-4443
30. Liu C Sun H Huang W Wang Z Fu C Han D Sintilimab as maintenance treatment for local/regional recurrent esophageal squamous carcinoma after concurrent chemoradiotherapy: a single-arm Ib/II phase study Front Immunol 2023 10.3389/fimmu.2023.1193394 38343438
Liu C, Sun H, Huang W, Wang Z, Fu C, Han D et al (2023) Sintilimab as maintenance treatment for local/regional recurrent esophageal squamous carcinoma after concurrent chemoradiotherapy: a single-arm Ib/II phase study. Front Immunol. 10.3389/fimmu.2023.119339438343438 10.3389/fimmu.2023.1193394
31. Nomura M Nagatomo R Doi K Shimizu J Baba K Saito T Association of short-chain fatty acids in the gut microbiome with clinical response to treatment with nivolumab or pembrolizumab in patients with solid cancer tumors JAMA Netw Open 2020 3 e202895 10.1001/jamanetworkopen.2020.2895 32297948
Nomura M, Nagatomo R, Doi K, Shimizu J, Baba K, Saito T et al (2020) Association of short-chain fatty acids in the gut microbiome with clinical response to treatment with nivolumab or pembrolizumab in patients with solid cancer tumors. JAMA Netw Open 3:e202895. 10.1001/jamanetworkopen.2020.289532297948 10.1001/jamanetworkopen.2020.2895
32. Smith PM Howitt MR Panikov N Michaud M Gallini CA Bohlooly YM The microbial metabolites, short-chain fatty acids, regulate colonic treg cell homeostasis Science 2013 341 569 573 10.1126/science.1241165 23828891
Smith PM, Howitt MR, Panikov N, Michaud M, Gallini CA, Bohlooly YM et al (2013) The microbial metabolites, short-chain fatty acids, regulate colonic treg cell homeostasis. Science 341:569–573. 10.1126/science.124116523828891 10.1126/science.1241165
33. Furusawa Y Obata Y Fukuda S Endo TA Nakato G Takahashi D Commensal microbe-derived butyrate induces the differentiation of colonic regulatory T cells Nature 2013 504 446 450 10.1038/nature12721 24226770
Furusawa Y, Obata Y, Fukuda S, Endo TA, Nakato G, Takahashi D et al (2013) Commensal microbe-derived butyrate induces the differentiation of colonic regulatory T cells. Nature 504:446–450. 10.1038/nature1272124226770 10.1038/nature12721
34. Arpaia N Campbell C Fan X Dikiy S van der Veeken J deRoos P Metabolites produced by commensal bacteria promote peripheral regulatory T-cell generation Nature 2013 504 451 455 10.1038/nature12726 24226773
Arpaia N, Campbell C, Fan X, Dikiy S, van der Veeken J, deRoos P et al (2013) Metabolites produced by commensal bacteria promote peripheral regulatory T-cell generation. Nature 504:451–455. 10.1038/nature1272624226773 10.1038/nature12726
35. Luu M Weigand K Wedi F Breidenbend C Leister H Pautz S Regulation of the effector function of CD8(+) T cells by gut microbiota-derived metabolite butyrate Sci Rep 2018 8 14430 10.1038/s41598-018-32860-x 30258117
Luu M, Weigand K, Wedi F, Breidenbend C, Leister H, Pautz S et al (2018) Regulation of the effector function of CD8(+) T cells by gut microbiota-derived metabolite butyrate. Sci Rep 8:14430. 10.1038/s41598-018-32860-x30258117 10.1038/s41598-018-32860-x
36. Fellows R Denizot J Stellato C Cuomo A Jain P Stoyanova E Microbiota derived short chain fatty acids promote histone crotonylation in the colon through histone deacetylases Nat Commun 2018 9 105 10.1038/s41467-017-02651-5 29317660
Fellows R, Denizot J, Stellato C, Cuomo A, Jain P, Stoyanova E et al (2018) Microbiota derived short chain fatty acids promote histone crotonylation in the colon through histone deacetylases. Nat Commun 9:105. 10.1038/s41467-017-02651-529317660 10.1038/s41467-017-02651-5
37. Yuille S Reichardt N Panda S Dunbar H Mulder IE Human gut bacteria as potent class I histone deacetylase inhibitors in vitro through production of butyric acid and valeric acid PLoS ONE 2018 13 e0201073 10.1371/journal.pone.0201073 30052654
Yuille S, Reichardt N, Panda S, Dunbar H, Mulder IE (2018) Human gut bacteria as potent class I histone deacetylase inhibitors in vitro through production of butyric acid and valeric acid. PLoS ONE 13:e0201073. 10.1371/journal.pone.020107330052654 10.1371/journal.pone.0201073
38. Woods DM Sodre AL Villagra A Sarnaik A Sotomayor EM Weber J HDAC inhibition upregulates PD-1 ligands in melanoma and augments immunotherapy with PD-1 blockade Cancer Immunol Res 2015 3 1375 1385 10.1158/2326-6066.CIR-15-0077-T 26297712
Woods DM, Sodre AL, Villagra A, Sarnaik A, Sotomayor EM, Weber J (2015) HDAC inhibition upregulates PD-1 ligands in melanoma and augments immunotherapy with PD-1 blockade. Cancer Immunol Res 3:1375–1385. 10.1158/2326-6066.CIR-15-0077-T26297712 10.1158/2326-6066.CIR-15-0077-T
39. Booth L Roberts JL Poklepovic A Kirkwood J Dent P HDAC inhibitors enhance the immunotherapy response of melanoma cells Oncotarget 2017 8 83155 83170 10.18632/oncotarget.17950 29137331
Booth L, Roberts JL, Poklepovic A, Kirkwood J, Dent P (2017) HDAC inhibitors enhance the immunotherapy response of melanoma cells. Oncotarget 8:83155–83170. 10.18632/oncotarget.1795029137331 10.18632/oncotarget.17950
40. Cao K Wang G Li W Zhang L Wang R Huang Y Histone deacetylase inhibitors prevent activation-induced cell death and promote anti-tumor immunity Oncogene 2015 34 5960 5970 10.1038/onc.2015.46 25745993
Cao K, Wang G, Li W, Zhang L, Wang R, Huang Y et al (2015) Histone deacetylase inhibitors prevent activation-induced cell death and promote anti-tumor immunity. Oncogene 34:5960–5970. 10.1038/onc.2015.4625745993 10.1038/onc.2015.46
41. Al-Qadami GH Secombe KR Subramaniam CB Wardill HR Bowen JM Gut microbiota-derived short-chain fatty acids: impact on cancer treatment response and toxicities Microorganisms 2022 10.3390/microorganisms10102048 36296324
Al-Qadami GH, Secombe KR, Subramaniam CB, Wardill HR, Bowen JM (2022) Gut microbiota-derived short-chain fatty acids: impact on cancer treatment response and toxicities. Microorganisms. 10.3390/microorganisms1010204836296324 10.3390/microorganisms10102048
