Gastrointestinal toxicities associated with immune checkpoint inhibitors: a disproportionality analysis leveraging VigiBase, the WHO Adverse Drug Reaction Database

Gastrointestinal toxicities associated with immune checkpoint inhibitors: a disproportionality analysis leveraging VigiBase, the WHO Adverse Drug Reaction Database 与免疫检查点抑制剂相关的胃肠道毒性：利用WHO药物不良反应数据库VigiBase进行的不成比例分析 1 equal first-author 2 equal 1 1 4 2 3 corresp Xiahong LIN, linxiahongdr@fjmu.edu.cn Xiahong LIN, linxiahongdr@fjmu.edu.cn linxiahongdr@fjmu.edu.cn https://orcid.org/0000-0002-5515-730X Department of Gastroenterology, the Second Affiliated Hospital of Fujian Medical University, Quanzhou362000, China Department of Gastroenterology, the Second Affiliated Hospital of Fujian Medical University, Quanzhou362000, China Department of Endocrinology, the Second Affiliated Hospital of Fujian Medical University, Quanzhou362000, China Department of Endocrinology, the Second Affiliated Hospital of Fujian Medical University, Quanzhou362000, China Department of Medical Administration, the Second Affiliated Hospital of Fujian Medical University, Quanzhou362000, China Department of Medical Administration, the Second Affiliated Hospital of Fujian Medical University, Quanzhou362000, China IT Application Department, Xiamen C&D Corporation Limited, Xiamen361000, China IT Application Department, Xiamen C&D Corporation Limited, Xiamen361000, China 目的 2 免疫检查点抑制剂（ICIs）可以显著提高某些晚期恶性肿瘤的生存率，但是，ICIs治疗也可能导致许多免疫相关的不良反应事件。我们的研究旨在鉴定和表征与ICIs相关的胃肠道不良反应事件。 创新点 2 鉴定和表征与ICIs相关的胃肠道不良反应事件，提高对ICIs所致胃肠道不良事件的认识。 方法 2 从世界卫生组织（WHO）药物不良反应数据库VigiBase获得2011年1月1日至2019年3月6日的药物不良反应数据，将接受ICIs治疗报告的胃肠道不良反应事件与整个数据库报告进行比较。通过计算信息成分（IC）和报告优势比（ROR）评估ICIs与胃肠道不良反应事件之间的关联。 结论 2 ICIs治疗可导致多种胃肠道不良反应事件，甚至可发生严重巨结肠。对于晚期恶性肿瘤患者进行ICIs临床诊疗时，需要考虑ICIs相关胃肠道不良反应事件。 免疫检查点抑制剂 胃肠道毒性 VigiBase 信息成分 报告优势比 With the improvement of people's living standards, gastrointestinal adverse reactions caused by various adverse factors have attracted more and more people's attention. A recent study has indicated that coronavirus disease 2019 (COVID-19) could also invade the gastrointestinal tract, leading to gastrointestinal adverse reactions ( Song et al., 2020 Song et al., 2020 ). In recent years, immunotherapy has provided certain effects for some patients with advanced malignant tumors. A microencapsulation of immunoglobulin Y (IgY) was reported to provide an effective way to preserve IgY and improve its performance in the gastrointestinal tract ( Zhang J et al., 2020 Zhang J et al., 2020 ). Immune checkpoint inhibitors (ICIs) can significantly improve the survival of some advanced malignant tumors, especially metastatic malignant melanoma and lung cancer ( Afzal et al., 2018 Afzal et al., 2018 ; Madden and Kasler, 2019 Madden and Kasler, 2019 ). They include anti-cytotoxic T lymphocyte-associated antigen-4 (anti-CTLA-4) antibodies (ipilimumab and tremelimumab), anti-programmed cell death protein 1 (anti-PD-1) antibodies (nivolumab and pembrolizumab), and anti-programmed death-ligand 1 (anti-PD-L1) antibodies (atezolizumab, avelumab, and durvalumab) ( Baxi et al., 2018 Baxi et al., 2018 ). Previous studies have shown that ICI combination therapy, such as nivolumab plus ipilimumab, has particular efficacy in lung cancer, renal cell carcinoma, and malignant melanoma ( Wolchok et al., 2017 Wolchok et al., 2017 ; Derosa et al., 2018 Derosa et al., 2018 ; Doroshow et al., 2019 Doroshow et al., 2019 ). However, ICIs may also lead to many immune-related adverse events (irAEs), even causing severe complications in certain cases. The most well-established toxicities from ICI therapy are gastrointestinal irAEs, including enteritis, enterocolitis, microscopic colitis, and gastritis, which have attracted public attention in recent years; reports of such events associated with ICI therapy also have increased ( Tandon et al., 2018 Tandon et al., 2018 ; de Malet et al., 2019 de Malet et al., 2019 ). These gastrointestinal irAEs may generally respond well to corticosteroids and infliximab ( Haanen et al., 2017 Haanen et al., 2017 ). Although most of these irAEs are low-grade, a lack of detection and timely treatment may incur severe or fatal complications. Many clinical oncologists and gastroenterologists are unfamiliar with gastrointestinal irAEs caused by ICI treatment, making it impossible to detect and deal with the resulting immunotoxicity in time. In addition, the previous scientific literature lacks comprehensive and detailed reports on gastrointestinal irAEs caused by ICIs, especially on cases of megacolon. In this study, we used the World Health Organization (WHO) global individual case safety report database, known as VigiBase (herein also referred to as Adverse Drug Reaction Database), which is managed by the Uppsala Monitoring Center in Sweden, to fully understand the gastrointestinal irAEs caused by ICI treatment, and their clinical characteristics. The present study is a disproportionality analysis leveraging VigiBase, which includes reports from more than 130 countries, and represents over 90% of the world's population. It contains more than 19 million individual case safety reports (ICSRs) submitted by national pharmacovigilance centers since 1967. These reports are generally notified post-marketing and originate from many kinds of sources, including pharmacists, healthcare professionals, patients, and physicians. Adverse drug reactions (ADRs) in VigiBase are coded according to the Medical Dictionary for Regulatory Activities (MedDRA). In the present observational, retrospective, and disproportionate analysis, based on the VigiBase database, we report suspicious gastrointestinal irAEs related to ICI therapy from January 1, 2011 to March 6, 2019, and describe the clinical features of cases in detail. The reference group consists of all the adverse reaction reports in VigiBase during the same study period. The main gastrointestinal irAEs are divided into 13 categories, namely enterocolitis, gastrointestinal perforation, megacolon, duodenitis, intestinal obstruction, esophagitis, diarrhea, colon operation, gastritis, inflammatory bowel disease, gastrointestinal hemorrhage, abdominal discomfort, and vomiting ( Table 1 Table 1 ). ICSRs are described as number (percentage). The information component (IC) reflects the strength of association between the specific treatment and the adverse drug event. Positive IC values are thresholds of signal detection within VigiBase. Different ICIs include ipilimumab, nivolumab, pembrolizumab, atezolizumab, durvalumab, and combination therapy (ipilimumab plus nivolumab, ipilimumab plus pembrolizumab, ipilimumab plus atezolizumab, pembrolizumab plus nivolumab, ipilimumab plus pembrolizumab plus nivolumab). All gastrointestinal irAEs were classified by group queries according to the Medical Dictionary for Regulatory Activities (MedDRA, Version 20.1). ICIs: immune checkpoint inhibitors; irAE: immune-related adverse event; ICSRs: individual case safety reports; CI: confidence interval. Gastrointestinal irAE ICSRs for ICIs (ICIs reports in total: 61 931) ICSRs in full database (reports in total: 13 300 773) Information component (95% CI) Enterocolitis 3066 (4.82%) 23 850 (0.18%) 4.80 (4.75‒4.85) Gastrointestinal perforation 380 (0.40%) 12 983 (0.10%) 2.68 (2.51‒2.80) Megacolon 15 (0.01%) 535 (0.004%) 2.46 (1.62‒3.05) Duodenitis 44 (0.06%) 4358 (0.03%) 1.19 (0.71‒1.54) Intestinal obstruction 259 (0.35%) 25 760 (0.19%) 1.19 (0.99‒1.33) Esophagitis 62 (0.10%) 7344 (0.06%) 0.85 (0.43‒1.15) Diarrhea 3246 (5.24%) 416 055 (3.13%) 0.74 (0.69‒0.79) Colon operation 22 (0.04%) 2858 (0.02%) 0.70 (-0.01‒1.21) Gastritis 166 (0.27%) 39 951 (0.30%) -0.16 (-0.42‒0.02) Inflammatory bowel disease 122 (0.20%) 42 884 (0.32%) -0.71 (-1.01‒0.49) Gastrointestinal hemorrhage 365 (0.59%) 131 244 (0.99%) -0.74 (-0.92‒0.62) Abdominal discomfort 1136 (1.83%) 520 487 (3.91%) -1.09 (-1.19‒1.02) Vomiting 2616 (4.22%) 1 248 590 (9.39%) -1.15 (-1.22‒1.11) Each adverse reaction report associated with ICI treatment includes patient characteristics (age and sex), management information (country, reporting date, and notifier), drug information (WHO drug name, indication, route of administration, dosage regimen, start and end dates), and ADR information (MedDRA classification terms, onset of ADRs, and final outcomes). The five ICI drugs reported in the study are anti-PD-L1 antibodies (atezolizumab and durvalumab), anti-CTLA-4 antibody (ipilimumab), and anti-PD-1 antibodies (nivolumab and pembrolizumab). A severe adverse event is defined as an event leading to any other medically important conditions that require hospitalization (initial or prolonged), is life-threatening, or causes death. It is worth noting that reports of ADRs were used for the purposes of this study starting from January 1, 2011. VigiBase is known as a case‒non-case analytic database; therefore, it was used for disproportionality analysis to assess whether suspected drug-induced gastrointestinal events were differentially reported between ICIs and other drugs in the full database. Gastrointestinal irAEs among different ICI regimens were also compared by disproportionality analyses, i.e., anti-PD-1 or anti-PD-L1 versus anti-CTLA-4 monotherapy, and monotherapy versus combination ICI therapy (anti-PD-1 or anti-PD-L1 plus anti-CTLA-4 combination therapy). The analyses aimed to identify adverse drug events by relative frequency, which is different from the overall reporting of events in the full database. The proportion of selected ADRs reported for ICIs was compared to the proportion in the full database. Disproportionality analysis can be calculated by the information component (IC) or the reported odds ratio (ROR). The earlier can provide a conservative association metric, and reduce the risk of highlighting false associations compared to the ROR, especially for events with very low expected frequencies in the VigiBase database. Values of IC are only used to compare adverse drug events with the full database, but cannot be used for comparisons of different ICI reporting events among ICI therapies. Therefore, the IC value was used to identify meaningful ICIs that induced irAEs, while the ROR was used to compare the reporting events of ADRs in different ICI subgroups. The value of IC, whose calculation is derived from a Bayesian confidence propagation neural network, is used to reflect the strength of the adverse drug event association ( Zhao et al., 2001 Zhao et al., 2001 ), which is expressed by the logarithm of prior and posterior probabilities of occurrence of ADRs. A positive IC value indicates that adverse drug events are reported more often than all reported events in the full database. The 95% confidence interval (CI) indicates the stability of IC values; the stability is higher when the 95% CI is narrower. Disproportionality for gastrointestinal irAEs induced by ICI subgroups was analyzed by calculating the ROR (95% CI). When the lower value of ROR (95% CI) was larger than one, adverse reactions for the target ICI were notable ADR signals in the adverse drug event. The Bonferroni adjustment method was used to perform the comparisons among different drug treatment regimens, and the ROR CI was adjusted by using P =0.01. The clinical characteristics of ADRs were summarized by descriptive statistical methods, while the quantitative variables were compared by using one-way analysis of variance (ANOVA). According to the VigiBase database, patients who received ICIs reported 61 931 adverse events, whereas patients who were administered any drug reported 13 300 773 adverse events between January 1, 2011 and March 6, 2019. Table 1 Table 1 shows the IC values for various gastrointestinal adverse events induced by ICI therapy compared to those for the same adverse event in the full database: ICI-associated enterocolitis (3066 reports for ICIs vs. 23 850 reports for the full database; IC 4.80 (95% CI 4.75‒4.85)); ICI-associated gastrointestinal perforation (380 reports for ICIs vs. 12 983 reports for the full database; IC 2.68 (95% CI 2.51‍‒‍2.80)); ICI-associated duodenitis (44 reports for ICIs vs. 4358 reports for the full database; IC 1.19 (95% CI 0.71‍‒‍1.54)); ICI-associated intestinal obstruction (259 reports for ICIs vs. 25 760 reports for the full database; IC 1.19 (95% CI 0.99‍‒‍‍1.33)). It is worth noting that 15 cases of the rarely reported ICI-associated megacolon were found (535 reports for the full database; IC 2.46 (95% CI 1.62‒3.05)). All IC values were positive for the above five gastrointestinal irAEs induced by ICIs, and the values of 95% CI were very narrow, which shows that these adverse events are markedly associated with ICI therapies. Thus, we focus on these five gastrointestinal irAEs to analyze differences between various ICI subgroups, and to explain the clinical characteristics of each gastrointestinal irAE. As demonstrated in Table 2 Table 2 , the ROR values of the five gastrointestinal irAE were markedly different between ICI therapies, and the ROR values of duodenitis, enterocolitis, and gastrointestinal perforation were the highest in ICI combination treatments (ROR 11.68 (95% CI 7.43‍‒‍18.34), ROR 93.09 (95% CI 85.85‍‒‍100.94), and ROR 5.77 (95% CI 3.98‍‒‍8.37), respectively). We also found that the three gastrointestinal irAEs of duodenitis, enterocolitis, and intestinal obstruction were overreported for patients subjected to ICI combination treatment, versus those who received ICI monotherapy: duodenitis (ROR 8.43 (95% CI 4.70‍‒‍15.10)), enterocolitis (ROR 3.98 (95% CI 3.64‍‒‍4.35)), and intestinal obstruction (ROR 1.94 (95% CI 1.37‍‒‍2.75)). Enterocolitis, gastrointestinal perforation, and megacolon were overreported for patients who received anti-CTLA-4 treatment, versus those subjected to anti-PD-1/PD-L1 treatment (ROR 3.87 (95% CI 3.57‒4.20), ROR 5.42 (95% CI 4.37‍‍‒‍6.73), and ROR 4.92 (95% CI 1.75‒13.82), respectively). Anti-CTLA-4 refers to any ICSR treated with ipilimumab. Anti-PD-1/PD-L1 refers to any ICSR treated with any of the following four drugs: nivolumab, pembrolizumab, atezolizumab, and durvalumab. ICI combination refers to any ICSR treated with anti-CTLA-4 (ipilimumab) in combination with any one or two of the anti-PD-1/PD-L1, or to any ICSR treated with anti-PD-1 in combination with anti-PD-L1. Comparisons between different drug regimens were performed using the Bonferroni adjustment method. ROR confidence intervals were calculated using P =0.01 to adjust. ROR: reported odds ratio； CI: confidence interval; ICI: immune checkpoint inhibitor； ADR: adverse drug reaction； Anti-CTLA-4: anti-cytotoxic T lymphocyte-associated antigen-4; ICSR: individual case safety report; Anti-PD-1: anti-programmed cell death protein 1; Anti-PD-L1: anti-programmed death-ligand 1. 2 Characteristics 2 Duodenitis 2 Enterocolitis 2 Gastrointestinal perforation 2 Intestinal obstruction 2 Megacolon n / n ROR (95% CI) n / n ROR(95% CI) n / n ROR (95% CI) n / n ROR (95% CI) n / n ROR (95% CI) Anti-CTLA-4 vs. full database 2/4 358 0.42 (0.11‒1.68) 1239/23 850 56.67 (53.42‒60.11) 214/12 983 15.97 (13.96‒18.27) 46/25 760 1.75 (1.32‒2.32) 9/535 15.71 (8.13‒30.36) Anti-PD-1/Anti-PD-L1 vs. full database 25/4358 1.68 (1.14‒2.47) 1143/23 850 14.52 (13.67‒15.41) 140/12 983 2.92 (2.46‒3.46) 182/25 760 2.06 (1.78‒2.38) 5/535 3.17 (1.42‒7.08) ICI combination vs. full database 17/4358 11.68 (7.43‒18.34) 684/23 850 93.09 (85.85‍‒‍100.94) 26/12 983 5.77 (3.98‒8.37) 31/25 760 3.84 (2.78‒5.31) 1/535 4.98 (0.70‒35.40) Anti-CTLA-4 vs. Anti-PD-1/Anti-PD-L1 2/25 0.25 (0.06‒1.06) 1 239/1 143 3.87 (3.57‒4.20) 214/140 5.42 (4.37‒6.73) 46/182 0.85 (0.62‒1.17) 9/5 4.92 (1.75‒13.82) ICI combination vs. monotherapy 17/ 27 8.43 (4.70‒15.10) 684/2382 3.98 (3.64‒4.35) 26/354 0.98 (0.67‒1.44) 31/228 1.94 (1.37‒2.75) 1/14 0.83 (0.11‒6.25) Events of ICI-associated enterocolitis, gastrointestinal perforation, intestinal obstruction, and duodenitis were reported mainly from the Americas (1292/3066 (42.14%), 193/379 (50.92%), 138/259 (53.28%), and 19/44 (43.18%), respectively), while most of the megacolon cases were recorded in Europe (5/15 (33.33%)), as shown in Table 3 Table 3 . There were more male patients than female ones for the five gastrointestinal irAEs except for megacolon (enterocolitis 60.88% vs. 39.12%; gastrointestinal perforation 67.24% vs. 32.76%; intestinal obstruction 60.40% vs. 39.60%; duodenitis 62.79% vs. 37.21%; megacolon 40.00% vs. 60.00%). We also found that reported events of enterocolitis, duodenitis, gastrointestinal perforation, megacolon, and intestinal obstruction, associated with ICI treatment, were observed mainly in patients with lung cancer or malignant melanoma. Data are expressed as number (percentage). a Notifier1 refers to physician, pharmacist, or other healthcare professional; Notifier2 refers to lawyer or consumer. b Indication refers to the primary tumors treated by ICIs. ICI: immune checkpoint inhibitor； ADR: adverse drug reaction. Basic information Enterocolitis （ n =3066） Gastrointestinal perforation （ n =379） Intestinal obstruction （ n =259） Duodenitis （ n =44） Megacolon （ n =15） Year 2011 23 (0.75%) 8 (2.11%) 4 (1.54%) 0 0 2012 84 (2.74%) 28 (7.39%) 9 (3.47%) 0 3 (20.00%) 2013 103 (3.36%) 20 (5.28%) 2 (0.77%) 0 2 (13.33%) 2014 233 (7.60%) 49 (12.93%) 10 (3.86%) 2 (4.55%) 0 2015 369 (12.04%) 79 (20.84%) 28 (10.81%) 5 (11.36%) 3 (20.00%) 2016 425 (13.86%) 45 (11.87%) 30 (11.58%) 7 (15.91%) 1 (6.67%) 2017 754 (24.59%) 55 (14.51%) 62 (23.94%) 10 (22.73%) 6 (40.00%) 2018 934 (30.46%) 88 (23.22%) 98 (37.84%) 15 (34.09%) 0 2019 141 (4.60%) 7 (1.85%) 16 (6.18%) 5 (11.36%) 0 Gender Female 1080/2761 (39.12%) 115/351 (32.76%) 99/250 (39.60%) 16/43 (37.21%) 9/15 (60.00%) Male 1681/2761 (60.88%) 236/351 (67.24%) 151/250 (60.40%) 27/43 (62.79%) 6/15 (40.00%) Age （year） 0‒17 3/2173 (0.14%) 0 0 0 0 18‒44 218/2173 (10.03%) 16/290 (5.52%) 14/205 (6.83%) 5/36 (13.89%) 1/13 (7.69%) 45‒65 870/2173 (40.04%) 117/290 (40.34%) 109/205 (53.17%) 16/36 (44.44%) 6/13 (46.15%) >65 1082/2173 (49.79%) 157/290 (54.14%) 82/205 (40.00%) 15/36 (41.67%) 6/13 (46.15%) Region Africa 3/3066 (0.10%) 0 1/259 (0.39%) 0 0 Americas 1292/3066 (42.14%) 193/379 (50.92%) 138/259 (53.28%) 19/44 (43.18%) 4/15 (26.67%) Asia 403/3066 (13.14%) 65/379 (17.15%) 61/259 (23.55%) 9/44 (20.45%) 4/15 (26.67%) Europe 1198/3066 (39.07%) 109/379 (28.76%) 51/259 (19.69%) 15/44 (34.09%) 5/15 (33.33%) Oceania 170/3066 (5.54%) 12/379 (3.17%) 8/259 (3.09%) 1/44 (2.27%) 2/15 (13.33%) Notifier a Notifier1 2391/2912 (82.11%) 289/366 (78.96%) 205/248 (82.66%) 40/42 (95.24%) 9/14 (64.29%) Notifier2 521/2912 (17.89%) 77/366 (21.04%) 43/248 (17.34%) 2/42 (4.76%) 5/14 (35.71%) Indication b Malignant melanoma 1533/2350 (65.23%) 168/277 (60.65%) 67/180 (37.22%) 14/34 (41.18%) 8/10 (80.00%) Lung cancer 608/2350 (25.87%) 78/277 (28.16%) 53/180 (29.44%) 11/34 (32.35%) 2/10 (20.00%) Kidney cancer 83/2350 (3.53%) 4/277 (1.44%) 9/180 (5.00%) 4/34 (11.76%) 0 Bladder cancer 44/2350 (1.87%) 10/277 (3.61%) 29/180 (16.11%) 1/34 (2.94%) 0 Gastric cancer 12/2350 (0.51%) 8/277 (2.89%) 8/180 (4.44%) 0 0 Prostate cancer 20/2350 (0.85%) 3/277 (1.08%) 2/180 (1.11%) 0 0 Colon cancer 13/2350 (0.55%) 1/277 (0.36%) 8/180 (4.44%) 2/34 (5.88%) 0 As shown in Table 4 Table 4 , reports of enterocolitis (1239 cases, 40.41%) and gastrointestinal perforation (214 cases, 56.32%) were the two most frequent ipilimumab-associated ADRs, while the most of intestinal obstruction cases (86 cases, 33.20%) were nivolumab-associated, and of duodenitis cases (16 cases, 36.36%) were ipilimumab plus nivolumab combination-associated. Megacolon was reported mainly under ipilimumab treatment (9 cases, 60.00%). In addition, there were a small number of reports of anti-PD-L1-associated gastrointestinal irAEs (87 cases of atezolizumab and 43 cases of durvalumab). We conducted a further analysis of follow-up reports on ICI-associated gastrointestinal irAEs. It was found that 1713 cases had the final outcomes reported, including "fatal," "not recovered/not resolved," and "recovered/resolved." Most patients in the enterocolitis, intestinal obstruction, and duodenitis cases recovered or resolved after appropriate treatment, while most of the gastrointestinal perforation cases (46.61%) had fatal consequences. The number of recovery reports of ICI-associated enterocolitis (71.70%) was higher than that for ICI-associated gastrointestinal perforation, intestinal obstruction, duodenitis, and megacolon combined. Four megacolon cases reported final outcomes: the patient recovered in one case and did not recover in another case, while two cases had fatal consequences. Data are expressed as number (percentage). Drug doses are expressed in VigiBase in two forms: mg/kg and total dose. Drug doses are grouped according to dosage and administration recommended in the drug prescription information. Recommended dosage for nivolumab: 3 mg/kg every 2 weeks, 240 mg every 2 weeks, or 480 mg every 4 weeks for different cancers. Recommended dosage for pembrolizumab: 200 mg every 3 weeks, 2 mg/kg every 3 weeks for different cancers. Recommended dosage for ipilimumab: 3 mg/kg every 3 weeks or 10 mg/kg every 3 weeks for different cancers. Recommended dosage for combined ICI therapy: 3 mg/kg nivolumab followed by 1 mg/kg Ipilimumab on the same day every 3 weeks for 4 doses, and then 240 mg nivolumab every 2 weeks or 480 mg every 4 weeks. ICI: immune checkpoint inhibitor； ADR: adverse drug reaction. ICI regimen/outcome Enterocolitis ( n =3066) Gastrointestinalperforation ( n =380) Intestinalobstruction ( n =259) Duodenitis ( n =44) Megacolon ( n =15) Drug group Ipilimumab 1239 (40.41%) 214 (56.32%) 46 (17.76%) 2 (4.55%) 9 (60.00%) Nivolumab 660 (21.53%) 67 (17.63%) 86 (33.20%) 11 (25.00%) 5 (33.33%) Pembrolizumab 406 (13.24%) 60 (15.79%) 58 (22.39%) 12 (27.27%) 0 Atezolizumab 46 (1.50%) 10 (2.63%) 30 (11.58%) 1 (2.27%) 0 Durvalumab 31 (1.01%) 3 (0.79%) 8 (3.09%) 1 (2.27%) 0 Ipilimumab plus nivolumab 656 (21.40%) 25 (6.58) 29 (11.20%) 16 (36.36%) 1 (6.67%) Ipilimumab plus pembrolizumab 19 (0.62%) 1 (0.26%) 1 (0.39%) 1 (2.27%) 0 Ipilimumab plus atezolizumab 1 (0.03%) 0 0 0 0 Pembrolizumab plus nivolumab 1 (0.03%) 0 0 0 0 Ipilimumab plus pembrolizumab plus nivolumab 7 (0.23%) 0 1 (0.39%) 0 0 Drug doses Monotherapy with ipilimumab 3 mg/kg 392/742 (52.83%) 61/136 (44.85%) 7/26 (26.92%) 0 2/7 (28.57%) 10 mg/kg 120/742 (16.17%) 22/136 (16.18%) 9/26 (34.62%) 1/1 (100.00%) 1/7 (14.29%) <500 mg 156/742 (21.02%) 43/136 (31.62%) 3/26 (11.54%) 0 4/7 (57.14%) 500‒1000 mg 47/742 (6.33%) 7/136 (5.15%) 4/26 (15.38%) 0 0 >1000 mg 27/742 (3.64%) 3/136 (2.21%) 3/26 (11.54%) 0 0 Monotherapy with nivolumab 1‒2 mg/kg 13/408 (3.19%) 5/53 (9.43%) 5/69 (7.25%) 0 0 ≥3 mg/kg 246/408 (60.29%) 26/53 (49.06%) 38/69 (55.07%) 4/8 (50.00%) 0 ≤240 mg 112/408 (27.45%) 19/53 (35.85%) 21/69 (30.43%) 4/8 (50.00%) 3/3 (100.00%) 240‒480 mg 37/408 (9.07%) 3/53 (5.66%) 5/69 (7.25%) 0 0 2 Monotherapy with pembrolizumab 2 mg/kg 61/247 (24.70%) 4/45 (8.89%) 7/44 (15.91%) 1/9 (11.11%) 0 ≤200 mg 186/247 (75.30%) 41/45 (91.11%) 37/44 (84.09%) 8/9 (88.89%) 0 Combination therapy Ipilimumab (3 mg/kg) plusnivolumab (1‒2 mg/kg） 150/367 (40.87%) 6/9 (66.67%) 8/17 (47.06%) 2/7 (28.57%) 0 Ipilimumab (3 mg/kg) plusnivolumab （≥3 mg/kg） 86/367 (23.43%) 2/9 (22.22%) 5/17 (29.41%) 2/7 (28.57%) 0 Ipilimumab (≤500 mg) plusnivolumab (≤240 mg) 124/367 (33.78%) 1/9 (11.11%) 3/17 (17.65%) 2/7 (28.57%) 0 Ipilimumab (≤500 mg) plusnivolumab (>240 mg) 7/367 (1.91%) 0 1/17 (5.88%) 1/7 (14.29%) 0 Outcome Recovered/resolved 960/1339 (71.70%) 82/221 (37.10%) 73/134 (54.48%) 8/15 (53.33%) 1/4 (25.00%) Not recovered/not resolved 252/1339 (18.82%) 36/221 (16.29%) 35/134 (26.12%) 7/15 (46.67%) 1/4 (25.00%) Fatal 127/1339 (9.48%) 103/221 (46.61%) 26/134 (19.40%) 0 2/4 (50.00%) Additionally, we analyzed time to onset for ICI-associated gastrointestinal irAEs. We found that the time to onset of enterocolitis associated with anti-CTLA-4 and ICI combination treatment was earlier compared to that associated with anti-PD-1/PD-L1 monotherapy (anti-CTLA-4 (55.44±3.25) d, anti-PD-1/PD-L1 (119.50±5.15) d, and combination therapy (58.49±4.64) d), and the time to onset of enterocolitis was not significantly different between anti-CTLA-4 and ICI combination treatments ( Fig. 1 Fig. 1 a). As shown in Fig. 1 Fig. 1 b, the time to onset of gastrointestinal perforation was not significantly different between anti-CTLA-4 and anti-PD-1/PD-L1 monotherapy (anti-CTLA-4 (58.08±6.45) d and anti-PD-1/PD-L1 (61.67±8.44) d, P =0.7998). Furthermore, the time to onset of intestinal obstruction, as shown in Fig. 1 Fig. 1 c, was not significantly different between anti-CTLA-4 and anti-PD-1/PD-L1 monotherapy (anti-CTLA-4 (45.40±9.89) d and anti-PD-1/PD-L1 (91.60±14.45) d, P =0.1760). Early clinical outcomes with ICI therapies have indicated that ICIs can improve patient survival; therefore, such therapies have been widely used to treat many malignant tumors, such as malignant melanoma ( Wolchok et al., 2017 Wolchok et al., 2017 ; Afzal et al., 2018 Afzal et al., 2018 ), renal cell carcinoma ( Derosa et al., 2018 Derosa et al., 2018 ), lung cancer ( Doroshow et al., 2019 Doroshow et al., 2019 ; Madden and Kasler, 2019 Madden and Kasler, 2019 ), and urothelial cancer ( Rodriguez-Vida et al., 2018 Rodriguez-Vida et al., 2018 ). Meanwhile, ICIs can also disturb the maintenance of patient immune homeostasis, as they suppress coinhibitory molecules between T-cells and other immune cells, which mediate the tumor killing process ( Sangro et al., 2020 Sangro et al., 2020 ). In addition, ICIs have side effects and toxicities in the process of tumor therapy, commonly referred to as irAEs. Therapies involving ICIs, such as anti-PD-1, anti-PD-L1, or anti-CTLA-4 antibodies, have been proved to effectively treat metastatic malignant melanoma and lung cancer ( Afzal et al., 2018 Afzal et al., 2018 ; Madden and Kasler, 2019 Madden and Kasler, 2019 ). However, they cause gastrointestinal irAEs, including enteritis, enterocolitis, microscopic colitis, and gastritis ( Tandon et al., 2018 Tandon et al., 2018 ; de Malet et al., 2019 de Malet et al., 2019 ). Additionally, certain severe or fatal irAEs were indicated in a previous study, including gastrointestinal perforation and intestinal obstruction associated with ICI therapy ( Abu-Sbeih and Wang, 2020 Abu-Sbeih and Wang, 2020 ). Thus far, the present study includes the largest and most extensive database of the clinical characteristics of ICI-associated gastrointestinal irAEs, acquired by the analysis of individual case safety reports from the WHO pharmacovigilance database. Consistently with previous studies, our results indicate that ICI-associated enterocolitis, duodenitis, gastrointestinal perforation, and intestinal obstruction are dramatically increased, and the associated risk posed by ICI combination treatment may be higher than that by ICI monotherapy. In addition, 15 cases of the rarely reported ICI-associated megacolon are included herein, which is infrequent in the clinical setting. Previous research has shown that gastrointestinal irAEs are closely related to anti-CTLA-4 or anti-PD-1/PD-L1 therapy ( Xu et al., 2018 Xu et al., 2018 ). It was observed in the present study that, compared to anti-PD-1/PD-L1 therapy, patients receiving anti-CTLA-4 therapy may have a higher risk of developing enterocolitis (ROR 3.87 (95% CI 3.57‍‒‍4.20)), gastrointestinal perforation (ROR 5.42 (95% CI 4.37‍‒‍6.73)), and megacolon (ROR 4.92 (95% CI 1.75‍‒‍13.82)). The combined ICI therapy of anti-CTLA-4 and anti-PD-1/PD-L1 has been suggested as highly efficient in treating malignant tumors ( Yuan et al., 2019 Yuan et al., 2019 ). Combined ICI therapy, however, may result in more severe immune-related ADRs ( Gu et al., 2019 Gu et al., 2019 ). Our study indicates that, in agreement with previous research, patients receiving combined ICI therapy may have a higher risk of developing gastrointestinal irAEs compared to ICI monotherapy, including duodenitis (ROR 8.43 (95% CI 4.70‍‒‍15.10)), enterocolitis (ROR 3.98 (95% CI 3.64‍‒‍4.35)), and intestinal obstruction (ROR 1.94 (95% CI 1.37‍‒‍2.75)). In the current study, it is demonstrated that most of the gastrointestinal irAEs occurred in patients with melanoma and lung cancer, with more cases in males than females, except for megacolon. Most of the gastrointestinal irAEs occurred within six weeks, and immune-related enterocolitis in ICI combination therapy manifested earlier than those in anti-PD-1/PD-L1 treatment, which was consistent with previous research ( Wang et al., 2018 Wang et al., 2018 ). Additionally, it is indicated that anti-CTLA-4 therapy had a dramatically earlier time to onset of enterocolitis than anti-PD-1/PD-L1 therapy, but no significant difference between the onset time of gastrointestinal perforation and intestinal obstruction was observed. We also analyzed cases of ICI-associated megacolon, which were very rare in the clinical setting, and had only been recorded as case reports in previous research ( Cho and Choi, 2020 Cho and Choi, 2020 ). Fifteen megacolon cases are featured herein, most of which involved patients with lung cancer or malignant melanoma, and occurred in anti-CTLA-4 therapy (ipilimumab). Interestingly, ICI-associated megacolon was mainly reported from Europe but not Americas. The possible reason is that megacolon is commonly named grade 4 colitis in Americas, and has been described similarly in previous research ( Wang et al., 2017 Wang et al., 2017 ). Clinically toxic megacolon requires rapid multidisciplinary assessment, and individual treatments need to be developed based on the underlying causes ( Leppkes et al., 2015 Leppkes et al., 2015 ). If the cause is likely an infection or inflammation, perioperative morbidity and mortality can be reduced by conservative treatment. The effect of treatment needs to be re-evaluated after 72 h and after 7 d to further ensure patient safety. Thus, the toxic megacolon adverse event needs to be closely monitored during treatment by ICIs, especially by anti-CTLA-4. The risk factors of ICI-related megacolon are not yet clear, and hence they need to be investigated in future clinical trials. It was observed in our study that most patients of the enterocolitis, intestinal obstruction, and duodenitis cases were recovered or resolved after precise treatment, while most of the gastrointestinal perforation cases had fatal consequences. The number of recovery reports for ICI-associated enterocolitis was found to be larger compared to ICI-associated gastrointestinal perforation, intestinal obstruction, duodenitis, and megacolon combined. Therefore, ICI-related enterocolitis is treated conservatively with most patients capable of recovery, and there is usually no need to discontinue the drug ( Zhang ML et al., 2020 Zhang ML et al., 2020 ). Additionally, one of the most common drug side effects, esophagitis, was absent in gastrointestinal irAEs of our comprehensive assessment, demonstrating that the esophagus is likely not involved in gastrointestinal irAEs associated with ICIs therapy. Thus, it seems fortunate that the esophagus, an integral section of the gastrointestinal tract, appears to be spared in the procession of ICI therapy. The VigiBase database has some limitations, which are also important to mention for the scope of this study. First, detailed information on clinical data, which may help to better evaluate patient responses related to irAEs, was missing from the VigiBase database. Second, when a report involved several drugs and/or several adverse events, we treated the adverse drug event pair as the basic unit rather than the reported event; the results of this pharmacovigilance analysis may thus be biased. Third, case reports of gastrointestinal disease associated with ICI therapies may not have been submitted to the VigiBase database, leading to a further bias in the database. Finally, the IC value does not indicate a causal relationship between ICIs and irAEs, but shows the related dependence of the ICI drugs and adverse event reports. In contrast to existing studies, however, the intensity of the large number of records at the national level supports our research aimed at quantifying the potential risks, but the true risks of these adverse events should be determined in prospective studies. Hence, a complete understanding of the limitations of VigiBase can help us better analyze ADRs, and produce useful clinical research hypotheses. The present study shows that the number of gastrointestinal irAEs, including enterocolitis, gastrointestinal perforation, duodenitis, and intestinal obstruction cases, has been rising dramatically, with several reported events of megacolon, which is rare in the clinical setting. Most gastrointestinal irAEs occur early during the course of ICI therapy. Consequently, it is important to raise an awareness of gastrointestinal irAEs associated with treatment by the ICI therapy of some advanced malignant tumors. References Abu-Sbeih H , Wang YH , 2020 . Gastrointestinal tract adverse events . In: Naing A, Hajjar J (Eds.), Immunotherapy . Springer, Cham , p. 247 - 253 . https://doi.org/10.1007/978-3-030-41008-7_12 https://doi.org/10.1007/978-3-030-41008-7_12 Gastrointestinal tract adverse events Afzal MZ , Mercado RR , Shirai K , 2018 . Efficacy of metformin in combination with immune checkpoint inhibitors (anti-PD-1/anti-CTLA-4) in metastatic malignant melanoma . J Immunother Cancer , 6 : 64 . https://doi.org/10.1186/s40425-018-0375-1 https://doi.org/10.1186/s40425-018-0375-1 Efficacy of metformin in combination with immune checkpoint inhibitors (anti-PD-1/anti-CTLA-4) in metastatic malignant melanoma Baxi S , Yang A , Gennarelli RL , et al. , 2018 . Immune-related adverse events for anti-PD-1 and anti-PD-L1 drugs: systematic review and meta-analysis . BMJ , 360 : k793 . https://doi.org/10.1136/bmj.k793 https://doi.org/10.1136/bmj.k793 Immune-related adverse events for anti-PD-1 and anti-PD-L1 drugs: systematic review and meta-analysis Cho JH , Choi JH , 2020 . Cytomegalovirus ileo-pancolitis presenting as toxic megacolon in an immunocompetent patient: a case report . World J Clin Cases , 8 ( 3 ): 552 - 559 . https://doi.org/10.12998/wjcc.v8.i3.552 https://doi.org/10.12998/wjcc.v8.i3.552 Cytomegalovirus ileo-pancolitis presenting as toxic megacolon in an immunocompetent patient: a case report de Malet A , Antoni G , Collins M , et al. , 2019 . Evolution and recurrence of gastrointestinal immune-related adverse events induced by immune checkpoint inhibitors . Eur J Cancer , 106 : 106 - 114 . https://doi.org/10.1016/j.ejca.2018.10.006 https://doi.org/10.1016/j.ejca.2018.10.006 Evolution and recurrence of gastrointestinal immune-related adverse events induced by immune checkpoint inhibitors Derosa L , Hellmann MD , Spaziano M , et al. , 2018 . Negative association of antibiotics on clinical activity of immune checkpoint inhibitors in patients with advanced renal cell and non-small-cell lung cancer . Ann Oncol , 29 ( 6 ): 1437 - 1444 . https://doi.org/10.1093/annonc/mdy103 https://doi.org/10.1093/annonc/mdy103 Negative association of antibiotics on clinical activity of immune checkpoint inhibitors in patients with advanced renal cell and non-small-cell lung cancer Doroshow DB , Sanmamed MF , Hastings K , et al. , 2019 . Immunotherapy in non-small cell lung cancer: facts and hopes . Clin Cancer Res , 25 ( 15 ): 4592 - 4602 . https://doi.org/10.1158/1078-0432.CCR-18-1538 https://doi.org/10.1158/1078-0432.CCR-18-1538 Immunotherapy in non-small cell lung cancer: facts and hopes Gu LH , Khadaroo PA , Su H , et al. , 2019 . The safety and tolerability of combined immune checkpoint inhibitors (anti-PD-1/PD-L1 plus anti-CTLA-4): a systematic review and meta-analysis . BMC Cancer , 19 : 559 . https://doi.org/10.1186/s12885-019-5785-z https://doi.org/10.1186/s12885-019-5785-z The safety and tolerability of combined immune checkpoint inhibitors (anti-PD-1/PD-L1 plus anti-CTLA-4): a systematic review and meta-analysis Haanen JBAG , Carbonnel F , Robert C , et al. , 2017 . Management of toxicities from immunotherapy: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up . Ann Oncol , 28 ( Suppl_4 ): iv119 - iv142 . https://doi.org/10.1093/annonc/mdx225 https://doi.org/10.1093/annonc/mdx225 Management of toxicities from immunotherapy: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up Leppkes M , Ganslmayer M , Strauß R , et al. , 2015 . Das toxic megacolon . Med Klin Intensivmed Notfmed , 110 ( 7 ): 500 - 505 . https://doi.org/10.1007/s00063-015-0076-1 https://doi.org/10.1007/s00063-015-0076-1 Das toxic megacolon Madden K , Kasler MK , 2019 . Immune checkpoint inhibitors in lung cancer and melanoma . Semin Oncol Nurs , 35 ( 5 ): 150932 . https://doi.org/10.1016/j.soncn.2019.08.011 https://doi.org/10.1016/j.soncn.2019.08.011 Immune checkpoint inhibitors in lung cancer and melanoma Rodriguez-Vida A , Perez-Gracia JL , Bellmunt J , 2018 . Immunotherapy combinations and sequences in urothelial cancer: facts and hopes . Clin Cancer Res , 24 ( 24 ): 6115 - 6124 . https://doi.org/10.1158/1078-0432.CCR-17-3108 https://doi.org/10.1158/1078-0432.CCR-17-3108 Immunotherapy combinations and sequences in urothelial cancer: facts and hopes Sangro B , Chan SL , Meyer T , et al. , 2020 . Diagnosis and management of toxicities of immune checkpoint inhibitors in hepatocellular carcinoma . J Hepatol , 72 ( 2 ): 320 - 341 . https://doi.org/10.1016/j.jhep.2019.10.021 https://doi.org/10.1016/j.jhep.2019.10.021 Diagnosis and management of toxicities of immune checkpoint inhibitors in hepatocellular carcinoma Song M , Li ZL , Zhou YJ , et al. , 2020 . Gastrointestinal involvement of COVID-19 and potential faecal transmission of SARS-CoV-2 . J Zhejiang Univ-Sci B (Biomed & Biotechnol) , 21 ( 9 ): 749 - 751 . https://doi.org/10.1631/jzus.B2000253 https://doi.org/10.1631/jzus.B2000253 Gastrointestinal involvement of COVID-19 and potential faecal transmission of SARS-CoV-2 Tandon P , Bourassa-Blanchette S , Bishay K , et al. , 2018 . The risk of diarrhea and colitis in patients with advanced melanoma undergoing immune checkpoint inhibitor therapy: a systematic review and meta-analysis . J Immunother , 41 ( 3 ): 101 - 108 . https://doi.org/10.1097/CJI.0000000000000213 https://doi.org/10.1097/CJI.0000000000000213 The risk of diarrhea and colitis in patients with advanced melanoma undergoing immune checkpoint inhibitor therapy: a systematic review and meta-analysis Wang DY , Ye F , Zhao SL , et al. , 2017 . Incidence of immune checkpoint inhibitor-related colitis in solid tumor patients: a systematic review and meta-analysis . Oncoimmunology , 6 ( 10 ): e1344805 . https://doi.org/10.1080/2162402X.2017.1344805 https://doi.org/10.1080/2162402X.2017.1344805 Incidence of immune checkpoint inhibitor-related colitis in solid tumor patients: a systematic review and meta-analysis Wang DY , Salem JE , Cohen JV , et al. , 2018 . Fatal toxic effects associated with immune checkpoint inhibitors: a systematic review and meta-analysis . JAMA Oncol , 4 ( 12 ): 1721 - 1728 . https://doi.org/10.1001/jamaoncol.2018.3923 https://doi.org/10.1001/jamaoncol.2018.3923 Fatal toxic effects associated with immune checkpoint inhibitors: a systematic review and meta-analysis Wolchok JD , Chiarion-Sileni V , Gonzalez R , et al. , 2017 . Overall survival with combined nivolumab and ipilimumab in advanced melanoma . N Engl J Med , 377 ( 14 ): 1345 - 1356 . https://doi.org/10.1056/NEJMoa1709684 https://doi.org/10.1056/NEJMoa1709684 Overall survival with combined nivolumab and ipilimumab in advanced melanoma Xu C , Chen YP , Du XJ , et al. , 2018 . Comparative safety of immune checkpoint inhibitors in cancer: systematic review and network meta-analysis . BMJ , 363 : k4226 . https://doi.org/10.1136/bmj.k4226 https://doi.org/10.1136/bmj.k4226 Comparative safety of immune checkpoint inhibitors in cancer: systematic review and network meta-analysis Yuan ZH , Yang HK , Wei YM , 2019 . Combined induction with anti-PD-1 and anti-CTLA-4 antibodies provides synergistic antitumor effects in DC-CIK cells in renal carcinoma cell lines . Int J Clin Exp Pathol , 12 ( 1 ): 123 - 132 . Combined induction with anti-PD-1 and anti-CTLA-4 antibodies provides synergistic antitumor effects in DC-CIK cells in renal carcinoma cell lines Zhang J , Li HH , Chen YF , et al. , 2020 . Microencapsulation of immunoglobulin Y: optimization with response surface morphology and controlled release during simulated gastrointestinal digestion . J Zhejiang Univ-Sci B (Biomed & Biotechnol) , 21 ( 8 ): 611 - 627 . https://doi.org/10.1631/jzus.B2000172 https://doi.org/10.1631/jzus.B2000172 Microencapsulation of immunoglobulin Y: optimization with response surface morphology and controlled release during simulated gastrointestinal digestion Zhang ML , Neyaz A , Patil D , et al. , 2020 . Immune-related adverse events in the gastrointestinal tract: diagnostic utility of upper gastrointestinal biopsies . Histopathology , 76 ( 2 ): 233 - 243 . https://doi.org/10.1111/his.13963 https://doi.org/10.1111/his.13963 Immune-related adverse events in the gastrointestinal tract: diagnostic utility of upper gastrointestinal biopsies Zhao SZ , Reynolds MW , Lefkowith J , et al. , 2001 . A comparison of renal-related adverse drug reactions between rofecoxib and celecoxib, based on the World Health Organization/Uppsala Monitoring Centre safety database . Clin Ther , 23 ( 9 ): 1478 - 1491 . https://doi.org/10.1016/s0149-2918(01)80121-1 https://doi.org/10.1016/s0149-2918(01)80121-1 A comparison of renal-related adverse drug reactions between rofecoxib and celecoxib, based on the World Health Organization/Uppsala Monitoring Centre safety database The study design was created by Xiahong LIN. Data collection and analysis was performed by Sifu HUANG, Xuefeng BAI, and Kainan ZHENG. Taiyong FANG and Yanta GUO conducted the literature search. Sifu HUANG and Xuefeng BAI wrote and edited the manuscript, and they contributed equally to this study. Xiahong LIN, Sifu HUANG, and Xuefeng BAI were responsible for the final modification of the manuscript. All authors have read and approved the final version of the manuscript. The supplied data come from various sources from VigiBase, and the probability that the suspected adverse effect is drug-related is not the same in all cases. The information does not represent the opinion of the Uppsala Monitoring Center or the WHO. Camilla Westerberg of the custom search team at the Uppsala Monitoring Centre (Uppsala, Sweden) research department is thanked for his help with the data extraction. 10.1631/jzus.B2000449 1673-1581（2021）02-0156-09 HUANG Sifu,BAI Xuefeng,FANG Taiyong et al., 2021. Gastrointestinal toxicities associated with immune checkpoint inhibitors: a disproportionality analysis leveraging VigiBase, the WHO Adverse Drug Reaction Database. Journal of Zhejiang University-SCIENCE B(Biomedicine & Biotechnology), 22(2):156-164. HUANG Sifu,BAI Xuefeng,FANG Taiyong et al., 2021. Gastrointestinal toxicities associated with immune checkpoint inhibitors: a disproportionality analysis leveraging VigiBase, the WHO Adverse Drug Reaction Database. Journal of Zhejiang University-SCIENCE B(Biomedicine & Biotechnology), 22(2):156-164. 2020-08-07 2020-11-08 2021-02-15 2022-05-09 © Zhejiang University Press 2021 Sifu HUANG, Xuefeng BAI, Taiyong FANG, Yanta GUO, Kainan ZHENG, and Xiahong LIN declare that they have no conflicts of interest. This article does not contain any studies with human or animal subjects performed by any of the authors. Compliance with ethics guidelines 浙江大学学报（英文版）（B辑：生物医学和生物技术） 2 22