Efficacy and safety of sirolimus in the treatment of gastrointestinal angiodysplasias

Abstract

BACKGROUND

Gastrointestinal angiodysplasias (GIAD) causes recurrent bleeding, and current treatments have limitations. Sirolimus, a mammalian target of rapamycin inhibitor, shows promise in inhibiting abnormal angiogenesis.

AIM

To evaluate the efficacy and safety of sirolimus in reducing bleeding episodes and improving clinical outcomes in patients with GIAD.

METHODS

We conducted a self-controlled study with 11 patients taking oral sirolimus. Retrospective data were collected prior to treatment, and prospective data were gathered during the study. Efficacy was assessed primarily by comparing bleeding episodes before and after sirolimus, with measurements at 3 and 6 months post-administration. The initial dose was 0.8 mg/m² once daily, adjusted to maintain trough blood concentrations between 5-10 ng/mL. Secondary outcomes included hemoglobin (Hb) levels, blood transfusion volume, and vascular lesions. Safety was monitored by tracking adverse reactions.

RESULTS

The average number of bleeding episodes decreased significantly from 2.09 ± 1.04 to 1.00 ± 0.75 in the 3 months preceding treatment, and from 3.80 ± 1.93 to 2.00 ± 1.63 in the 6 months preceding treatment. Sirolimus also increased Hb levels, reduced the need for transfusions, and decreased vascular lesions, improving clinical outcomes. All adverse effects were mild and resolved or improved within 1 week to 1 month without stopping sirolimus or needing lipid-lowering treatment.

CONCLUSION

Sirolimus reduced bleeding and transfusion needs while improving Hb levels in GIAD patients. Although these findings are encouraging, the limited sample size and lack of a control group warrant caution. Future controlled trials with larger populations are needed to validate sirolimus’s potential in GIAD.

Key Words: Gastrointestinal angiodysplasias; Sirolimus; Bleeding; Efficacy; Safety

Core Tip: This study indicates that sirolimus, a mammalian target of rapamycin inhibitor, effectively reduces bleeding episodes and improves hemoglobin levels in patients with gastrointestinal angiodysplasias (GIAD). By decreasing transfusions requirements and reducing vascular lesions, sirolimus shows promise as a novel therapeutic strategy. The treatment was generally well-tolerated, with mild and manageable side effects. While these findings are encouraging, future larger, controlled trials are needed to validate sirolimus’s role in managing GIAD.

INTRODUCTION

Gastrointestinal angiodysplasias (GIAD) is a critical condition affecting the gastrointestinal (GI) vasculature, accounting for 10% of all GI bleeding cases and 50% of small bowel bleeding cases[1]. It is characterized by fragile and dilated blood vessels within the mucosa and submucosa, often covered solely by endothelial cells lacking the necessary smooth muscle layers, rendering them highly susceptible to bleeding[2]. Clinically, GIAD manifests as recurrent, occult or overt GI bleeding, frequently leading to repeated hospitalizations or reliance on blood transfusions[3]. Approximately 40%-50% of patients with symptomatic blood loss due to GIAD experience recurrent bleeding[4]. GIAD-associated bleeding ranges from occult to overt and even acute massive hemorrhage, which can be life-threatening[5]. Patients often require long-term iron supplementation and recurrent blood transfusions to manage anemia[6]. According to the Yano-Yamamoto endoscopic classification, GIAD can appear as type 1a (punctate erythema, diameter < 1 mm) and type 1b (patchy erythema, diameter several millimeters), which may or may not be associated with blood oozing[7]. The mortality rate from GIAD-related bleeding can reach up to 3.5%, posing a severe threat to health and life[8,9]. The hidden, multiple, and regeneratively active lesions of GIAD present formidable challenges for clinical diagnosis and treatment, underscoring the urgent need for advanced medical intervention.

Current therapeutic options, including endoscopic therapy, vascular embolization, pharmacotherapy, and surgery, each face their own challenges and limitations[3,10]. Although beneficial in certain cases, none provide a universally safe and effective solution. For example, the long-term efficacy of endoscopic treatment does not consistently surpass that of no treatment at all[11]. Vascular embolization can target active bleeding sites but is limited by the rate of bleeding and the risk of complications such as tissue ischemia[12]. Pharmacological treatments, such as thalidomide and somatostatin analogs, show promise but are limited by side effects and administration methods[13,14]. While surgical intervention can offer definitive results, its invasive nature makes it unsuitable for patients who cannot tolerate surgery and anesthesia, and for those with widespread lesions[15].

In this context, there is an urgent need to develop new therapeutic agents. Sirolimus, also known as rapamycin, is a mammalian target of rapamycin (mTOR) pathway inhibitor that has shown significant potential in inhibiting abnormal angiogenesis[16,17]. The mTOR signaling pathway plays a central role in cell growth, proliferation, metabolism, and survival, and its dysregulation is linked to angiogenesis disorders[18,19]. Although the exact pathogenesis of GIAD remains unclear, the mTOR pathway is a promising therapeutic target due to its involvement in angiogenesis and vascular maintenance. By targeting this pathway, sirolimus may help regulate the angiogenesis, potentially treating GIAD. Sirolimus has shown therapeutic efficacy in inhibiting abnormal blood vessel formation in the skin, cornea, and tumors, indirectly supporting its potential use for GIAD[20-22].

Currently, there have been no reports on the use of sirolimus for GIAD-related bleeding. However, given its success in other areas, exploring its potential for GIAD treatment is warranted. This study aims to evaluate the efficacy and safety of sirolimus in treating GIAD-associated bleeding. We hope to provide new strategies for GIAD treatment, improve patient outcomes, and offer a scientific basis for future treatment guidelines.

MATERIALS AND METHODS

Study population and supervision

From March 2021 to March 2022, patients diagnosed with recurrent GI bleeding due to GIAD at the Department of Gastroenterology, Air Force Medical Center were screened. Inclusion criteria were as follows: (1) Age between 35 and 80, both genders. Female patients had to use contraception or have undergone tubal ligation; (2) Good organ function: Aspartate aminotransferase and alanine aminotransferase ≤ 2.5 times the upper limit of normal (ULN); Bilirubin and creatinine ≤ 1.5 times ULN; (3) Confirmed diagnosis of GIAD through capsule or double-balloon enteroscopy, with at least four bleeding episodes in the past year; and (4) Signed informed consent. Exclusion criteria included: (1) Allergy to sirolimus; (2) Surgery within the last month; (3) Serious health conditions such as cirrhosis, severe cardiovascular, respiratory, renal, hepatic, hematologic, or rheumatic diseases, or uncontrolled diabetes/hypertension; (4) Severe bilateral peripheral neuropathy or a history of seizures; (5) Use of corticosteroids, nonsteroidal anti-inflammatory drugs, antiplatelets, anticoagulants, or traditional Chinese medicine; (6) Ongoing chemotherapy/radiotherapy; (7) Pregnancy/breastfeeding; (8) Alcohol or drug abuse; and (9) Participation in conflicting clinical trials within the past month[23].

The protocol was reviewed and approved by the Ethics Committee of the Air Force Medical Center (No. 2021-97-PJ01). All participants provided written informed consent prior to enrollment. All trial activities and oversight adhered to the principles of the Declaration of Helsinki, the Good Clinical Practice guidelines set forth by the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use, and other relevant regulatory standards. The authors ensure the integrity and accuracy of the data and affirm that the trial was conducted in strict accordance with the approved protocol.

Study design

We conducted a self-controlled study where patients were administered oral sirolimus capsules (Yixinke; North China Pharmaceutical Group Corporation, Hebei Province, China). Retrospective patient history data were collected before treatment, with prospective data gathered during the study. To ensure consistency, both retrospective and prospective data collection adhered to the same clinical thresholds and monitoring protocols, including standardized follow-up schedules, laboratory assessments, and criteria for any supportive treatments (e.g., blood transfusions, iron supplementation). Efficacy was assessed by comparing pre- and post-treatment data. Adverse reactions were monitored to evaluate safety. The initial dose was 0.8 mg/m² of body surface area once daily. Plasma concentrations of sirolimus were measured at 1-, 3-, and 6 months post-administration. The dosage was adjusted to maintain trough concentrations between 5 and 10 ng/mL, based on treatments for lymphangioleiomyomatosis and blue rubber bleb nevus syndrome[24,25]. After administration, patients were hospitalized for intensive monitoring for the first week or longer. The study drug was discontinued temporarily or permanently if adverse reactions occurred, based on severity. Concomitant treatments, such as blood transfusions and iron supplementation, were allowed when needed. Blood transfusions were administered and recorded when hemoglobin (Hb) levels fell below 70 g/L (two units for Hb 61 g/L ≤ Hb ≤ 70 g/L, three units for Hb 51 g/L ≤ Hb ≤ 60 g/L, and four units for Hb ≤ 50 g/L). Iron supplementation (100 mg, four times per day) was allowed for Hb levels between 71 g/L and 110 g/L.

Baseline and follow-up assessments

During the first month of treatment, follow-ups were conducted weekly, then biweekly thereafter. Patients maintained a detailed daily diary of stool color, volume, frequency, and consistency. Biweekly fecal occult blood test (FOBT) were performed. Laboratory tests, including Hb, complete blood count, blood biochemistry, D-dimer, and coagulation markers, were conducted at baseline, 3 months, and 6 months. For patients with positive routine FOBT results, daily FOBT was performed until three consecutive negative results, ensuring accurate detection and cessation of bleeding. Additionally, any signs of significant bleeding, such as hematemesis, melena, hematochezia, or a sharp drop in Hb, prompted daily FOBT throughout the study.

Efficacy and safety evaluation

The primary objective of this study was to assess efficacy, with the main endpoint being the frequency of post-treatment bleeding episodes. We also tracked changes in Hb levels, transfusion rates, and transfusion volumes, along with the severity and duration of symptoms like dizziness and fatigue. The overall clinical effectiveness of sirolimus was scored using a dedicated scale (Table 1).

Table 1 Clinical effectiveness scoring system for sirolimus treatment.

Score	0	1	2	3	4
Bleeding episode	0	1	2-3	4-6	> 6
Duration of bleeding (days)	0	≤ 7	8-30	31-60	> 60
Hb (g/L)	≥ 120	90-120	60-90	30-60	< 30
Blood transfusion (mL)	0	≤ 200	200-400	400-800	> 800
Severity of dizziness and fatigue	None	Mild, does not affect work or daily life	Moderate, partially affects work and daily life	Severe, significantly affects work and daily life	Incapacitating, unable to perform daily work and life activities, requires symptomatic treatment
Duration of dizziness and fatigue (days)	0	≤ 15	15-30	30-45	> 45

Hb: Hemoglobin.

Bleeding outcomes were identified by the presence of overt bleeding (melena or hematochezia) and/or a positive FOBT in patients not on iron supplements. For those on iron supplements, bleeding was indicated by stool color changes or darkening with reduced Hb levels compared to prior tests. A bleeding episode was considered resolved after three consecutive days of negative FOBT following a positive test. The duration of a bleeding episode was the time from the first positive FOBT to the first of three sequential negative results. All bleeding events were solely attributed to GIAD. After six months of treatment, follow-up evaluations of lesions were conducted by the same experienced endoscopist using capsule or double-balloon enteroscopy. Safety was assessed by documenting adverse events, including any negative health changes such as new or worsening symptoms or abnormal lab results during the study.

Statistical analysis

Continuous variables were presented as mean ± SD (range), while categorical variables were expressed as counts (%). Prior to conducting tests on continuous variables, we used the Shapiro-Wilk test to check for normality. When data were normally distributed (P > 0.05), we applied the independent t test; otherwise, we used the Wilcoxon rank-sum test. Categorical variables were compared using Fisher’s exact test. Statistical analysis was conducted using the SPSS software package version 26.0 (SPSS Inc., Chicago, IL, United States) and GraphPad Prism version 10.1.2 (GraphPad Software, San Diego, CA, United States). A P value of less than 0.05 was considered statistically significant.

RESULTS

Patient characteristics

From March 2021 to March 2022, 11 patients diagnosed with GIAD were enrolled in the study, comprising 3 males and 8 females. The average age of the patients was 60.45 ± 11.63 years (range: 39-74 years), with a median disease duration of 24 months (range: 0.5-168 months) and a mean follow-up period of 9.94 ± 3.61 months (range: 3-15 months). All patients satisfied the diagnostic criteria established in the literature. Typical endoscopic findings of GIAD are depicted in Figure 1. Each patient exhibited multiple areas of angiodysplasias.

Figure 1 Typical endoscopic images of intestinal angiodysplasias. A: At 50 cm from the pylorus, multiple punctate erythemas are observed, some with blood seepage, classified as Yano-Yamamoto type 1a; B: At 150 cm from the pylorus in the jejunum, after removal of blood clots and irrigation, two sites of non-pulsatile active bleeding are visible, classified as type 1a; C: At 270 cm from the ileocecal valve, patchy erythema is observed without seepage, classified as type 1b; D: At 100 cm from the pylorus in the jejunum, active bleeding is evident; after irrigation, no pulsation is detected, and the base of the erythema is larger than 1 mm, classified as type 1b. Indicated by black arrows.

All participants received sirolimus treatment for more than 3 months, with ten treated for over 6 months, and three for more than 12 months, the longest period being 15 months. No patients withdrew from the study. Demographic details, clinical features, treatments, and adverse events for the patients are summarized in Table 2.

Table 2 Patients’ principal characteristics, management, and adverse events.

No.	Gender	Age	Disease course	Clinical symptoms	Comorbidities	Past treatment	Dosage of sirolimus	Adverse events
1	Female	66	3 years	Melena	None	Endoscopic	2 mg, q.d.	Mouth ulcers, diarrhea
2	Female	62	6 months	Melena	Bronchial asthma		2 mg, q.d.	Elevated triglycerides
3	Male	49	14 years	Hematochezia	None	Surgery	1 mg, q.d.	Pulmonary infection
4	Female	64	5 years	Melena	Hypertension, bronchial asthma, mitral regurgitation	Endoscopic	2 mg, q.d.	Diarrhea
5	Male	48	11 months	Melena	Hypertension, pituitary tumor, multiple hepatic hemangiomas	Endoscopic	1 mg, q.d.	None
6	Female	68	1 year	Hematochezia	Hypertension, type 2 diabetes		2 mg, q.d.	Mouth ulcers
7	Female	70	20 months	Melena	Aortic valve stenosis with regurgitation, mitral stenosis		2 mg, q.d.	None
8	Female	39	9 years	Melena	None	Endoscopic, Surgery	2 mg, q.d.	Mouth ulcers
9	Male	52	2 years	Melena	Old cerebral infarction		2 mg, q.d.	Mouth ulcers, rash
10	Female	73	8 months	Melena	Pulmonary emphysema		1.5 mg, q.d.	None
11	Female	74	2 years	Melena	Pulmonary emphysema; atrial fibrillation		1 mg, q.d.	None

q.d.: Quaque die.

Nine patients presented with melena accompanied by anemia, while two had hematochezia and anemia. Ten patients (90.91%) required long-term or intermittent iron supplementation. None had a history of long-term use of antiplatelet or anticoagulant medications. Figure 2 presents the changes in patient management before and after sirolimus treatment. Within the 15 months preceding sirolimus initiation, all patients had received blood transfusions, and four had undergone endoscopic treatment, with two patients requiring more than one endoscopic procedure, and two had surgical interventions.

Figure 2 Schematic overview of the clinical management of patients with gastrointestinal angiodysplasias before and after sirolimus treatment. The timelines highlight blood transfusions, endoscopic treatments, and sirolimus administration.

Sirolimus reduced the number of bleeding episodes

Sirolimus treatment resulted in a significant reduction in bleeding episodes. Post-treatment, the average frequency of episodes in 11 patients decreased from 2.09 ± 1.04 to 1.00 ± 0.75 compared to the 3-month pre-treatment period. Similarly, following sirolimus administration, the mean number of bleeding episodes in 10 patients over the 6-month pre-treatment period significantly dropped from 3.80 ± 1.93 to 2.00 ± 1.63 (Figure 3A).

Figure 3 Before and after 3 months and 6 months of sirolimus administration. A: Average bleeding episodes; B: Average hemoglobin concentration; C: The clinical effectiveness score. ^bP < 0.01. ^cP < 0.001. P were compared with pre-sirolimus. Hb: Hemoglobin.

Sirolimus increased Hb levels

Despite intermittent blood transfusions, all patients initially experienced anemia with an average Hb level of 77.64 ± 10.56 g/L (range: 57.43-97.68 g/L) before treatment. Following sirolimus administration, serum Hb levels significantly improved, rising from 78.29 ± 15.10 g/L at baseline to 103.80 ± 13.24 g/L at 3 months, and from 80.49 ± 12.63 g/L at baseline to 107.72 ± 16.93 g/L at 6 months (Figure 3B).

Sirolimus alleviated the need for blood transfusions in patients

During a follow-up period of up to 15 months, only two patients (case 4 and case 5) required blood transfusions, both of whom had high lesion loads and multiple comorbidities. Among the 11 participants treated with sirolimus for over 3 months, 90.91% had received transfusions in the 3 months prior to enrollment, but this figure dropped to 18.18% after 3 months of treatment. Similarly, all 10 participants who continued sirolimus for over 6 months had required transfusions in the year before inclusion, whereas only 20.00% needed transfusions during the initial 6 months of therapy (Figure 2). Therefore, sirolimus markedly reduces the necessity for blood transfusions. Eight patients (72.73%) still required intermittent oral iron supplementation, with no significant reduction in iron demand compared to before treatment.

Sirolimus reduced the volume of blood transfusions

Compared to the 3 months before sirolimus treatment, the median transfusion volume for the 11 patients significantly decreased from 400 mL (range: 0-5000 mL) to 0 mL (range: 0-1200 mL). Similarly, comparing the 6 months before treatment, the median transfusion volume for 10 patients significantly dropped from 800 mL (range: 400-10400 mL) to 0 mL (range: 0-2300 mL) (Table 3).

Table 3 Median transfusion volume before and after sirolimus treatment.

Blood transfusions (mL)	Pre-sirolimus	Post-sirolimus	Z value	P value
3 months	400 (0, 5000)	0 (0, 1200)	-2.823	0.005
6 months	800 (400, 10400)	0 (0, 2300)	-2.807	0.005

Sirolimus reduced vascular lesions

Visible improvements in lesion size and characteristics were observed. Patients with GIAD were monitored using double-balloon enteroscopy. Before treatment, GIAD lesions presented significant bleeding within the intestinal tract, with the affected area appearing red and possibly involving inflammation (Figure 4A). Six months after sirolimus treatment, the bleeding ceased, the intestinal wall returned to normal, and the surface became smooth and evenly colored, with no signs of bleeding or erythema, indicating a successful treatment outcome (Figure 4B). Representative histopathological images are shown in Figure 4C.

Figure 4 Endoscopic and histopathological observations of intestinal angiodysplasias. A: Endoscopic image showing significant patchy erythema and bleeding before sirolimus treatment; B: Endoscopic image after sirolimus treatment, revealing a significant reduction in vascular lesions; C: Histopathological image of intestinal angiodysplasias. scale bar: 100 μm.

Sirolimus enhanced clinical outcomes

We evaluated the clinical efficacy of sirolimus treatment. Compared to 3 months before treatment, the clinical effectiveness score for the 11 patients significantly decreased from 12.00 ± 3.46 to 5.00 ± 3.75 after sirolimus treatment. Similarly, comparing 6 months before treatment, the score for the 10 patients significantly dropped from 15.40 ± 3.57 to 5.90 ± 4.23 after sirolimus treatment (Figure 3C), indicating a significant clinical benefit from sirolimus.

Adverse events

Adverse events related to sirolimus treatment were summarized in Table 2, based on the Common Terminology Criteria for Adverse Events. Among the 11 patients, 7 (63.64%) experienced adverse reactions. Four patients (36.36%) developed oral ulcers, two (18.18%) had mild abdominal discomfort with increased bowel movements, one (9.09%) had a scattered rash, and one (9.09%) experienced mild to moderate elevations in triglycerides (2.14-2.36 mmol/L). All these adverse effects resolved or significantly improved within 1 week to 1 month without the need to discontinue sirolimus or initiate lipid-lowering treatment. One patient discontinued sirolimus after 8 months due to a pulmonary infection and was treated with antibiotics.

DISCUSSION

GIAD primarily affects individuals over 60 years old and is associated with complex etiology, often linked to conditions such as aortic valve stenosis, von Willebrand disease, chronic renal failure, and the use of left ventricular assist devices for end-stage heart failure[26-29]. Approximately 67.1%-78% of these lesions are located in the proximal small intestine, with multiple lesions are more common than solitary ones[30,31]. Patients typically experience recurrent bleeding, requiring long-term iron supplementation or even blood transfusions, severely impacting their health and safety. In this study, the 11 patients included 3 males and 8 females, with an average age of 60.45 ± 11.63 years (39-74), consistent with the literature. The median disease duration was 24 months (0.5-168). All patients required multiple blood transfusions during their disease course, and 90.91% required long-term oral iron therapy.

Treating bleeding from GIAD poses a significant clinical challenge, with no unified guidelines. Endoscopic treatment, vascular embolization, and surgical interventions have not yielded satisfactory results, likely because these methods do not address the underlying chronic mucosal ischemia and hypoxia, leading to new lesions. In this study, 4 patients continued to experience bleeding despite endoscopic treatment, and 2 patients had recurrent bleeding after surgical interventions, highlighting the urgent need for effective drugs to treat and prevent bleeding from GIAD. Previous research has explored various pharmacological treatments for this condition. Estrogen-progesterone therapy has proven ineffective[15,32]. Somatostatin analogs, which inhibit angiogenesis, reduce visceral blood flow, and improve platelet aggregation, can decrease rebleeding rates and transfusion needs, but their use is limited due to the necessity of injections and high costs[14]. Thalidomide shows anti-angiogenic effects by inhibiting vascular endothelial growth factor (VEGF) and basic fibroblast growth factor, but its high adverse event rate (71.4%) and severe complications (such as neuropathy and deep vein thrombosis) restrict its clinical application[23,33]. While previous therapies for GIAD (such as somatostatin analogs and thalidomide) have shown variable efficacy and tolerability, direct comparisons with sirolimus remain limited. Future randomized or comparative studies are needed to further clarify the place of sirolimus in GIAD management.

Previous studies have shown that serum levels of hypoxia-inducible factor 1α (HIF-1α) and angiopoietin-2 (ANG-2) were significantly elevated in patients with GIAD[34]. Holleran et al[35] also observed elevated serum ANG-2 levels in GIAD patients compared to controls, suggesting that these elevated factors may play a crucial role in GIAD development. HIF-1α increases the expression of VEGF and erythropoietin under hypoxic conditions, leading to enhanced vascular permeability and leakage[36,37]. ANG-2 promotes the formation of immature and unstable vessels[38]. Sirolimus, an mTOR inhibitor, suppresses HIF-1α and downregulates VEGF, making it a potential treatment for vascular malformations[39-41]. Le Cras et al[42] found that sirolimus significantly reduced ANG-2 Levels in patients with certain vascular tumors. Its efficacy in treating vascular malformations in children and adults, and in reducing GI bleeding and transfusion requirements in blue rubber bleb nevus syndrome, has been demonstrated in various studies[43,44]. Despite these promising results, specific studies on sirolimus for treating GIAD-related bleeding are still lacking.

Variations in study subjects and treatment strategies have left the onset time, optimal dosage, and duration of sirolimus treatment inconclusive. A systematic review suggests a common starting dose of 0.8 mg/m², with 35.7% of patients showing the clinical improvement within 7 days, and 64.3% within 14 days[45]. Lower blood concentrations of sirolimus (1-2 mg/day, with a trough concentration of 5 ng/mL) are associated with fewer side effects while maintaining efficacy[46]. Based on these studies, we targeted a concentration of 5-10 ng/mL, starting at 0.8 mg/m² orally once daily and adjusting based on blood levels. The average follow-up was 9.94 ± 3.61 months. Results showed significant quality of life improvements: After 3 and 6 months, clinical effectiveness scores, bleeding frequency, transfusion volumes, and Hb levels were improved. While 8 patients (72.73%) still required iron supplements for intermittent bleeding, overt bleeding frequency declined, and anemia symptoms like dizziness, fatigue, and palpitations were markedly alleviated. Transfusion requirements dropped, with only 2 patients (18.18%) needing transfusions, down from 100% before treatment. However, the side effects of sirolimus are dose-dependent. A review reported side effects including oral mucositis (31.9%), rash (8.2%), GI reactions (10.2%), hyperlipidemia (16.5%), and leukopenia (12.3%)[47]. In this study, 7 out of 11 patients (63.64%) experienced side effects, mainly oral ulcers and mild abdominal discomfort, which typically resolved within 1 week to 1 month. Sirolimus can inhibit T-cell proliferation and modulate immune activity, potentially leading to infections[48]. One patient discontinued due to a lung infection. As sirolimus is metabolized by cytochrome P450 3A4 and 3A5, its clearance can reduced by approximately 50% during infection or inflammation[49,50], necessitating dosage adjustments to ensure safety.

CONCLUSION

This study provides preliminary evidence of sirolimus's effectiveness in treating GI bleeding due to GIAD. Sirolimus reduced bleeding episodes, improved Hb levels, decreased transfusion dependence, and enhanced patients' quality of life, all with a favorable safety profile (Figure 5). Regular monitoring of blood counts and drug levels is essential. Although a control group would have strengthened the study’s conclusions, we did not include one due to the rarity and severity of GIAD and the ethical concerns of withholding treatment for actively bleeding patients. Future research should include larger sample sizes and longer follow-up periods to further validate sirolimus’s efficacy and safety, as well as to determine the optimal dosage and treatment duration.

Figure 5 Sirolimus treatment for patients with gastrointestinal angiodysplasias. q.d.: Quaque die.