1. Introduction

A novel coronavirus disease (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, was first identified in Wuhan, China, in December 2019 and has rapidly spread across continents.1,2 On March 11, 2020, the World Health Organization (WHO) declared SARS-CoV-2 a pandemic.3 The COVID-19 outbreak has seen a surge of patients with acute respiratory distress syndrome (ARDS) in intensive care units across the globe.4 SARS-CoV-2 infection can cause severe ARDS, pleural effusion, secondary spontaneous pneumothorax, and pneumomediastinum, which instigates severe hypoxemia.5–8

Vascular endothelial growth factor (VEGF) plays an important role in normal lung maintenance and the development of acute lung injury or ARDS.9 VEGF, also known as vascular permeability factor, is a signal protein produced by fibroblasts and is involved in both angiogenesis and vasculogenesis. The predominant source of VEGF in the lung is the alveolar epithelium.10–12 Hypoxia upregulates VEGF expression and thereby induces vascular leakiness in COVID-19–infected lung tissues. This results in plasma extravasation, which further increases tissue hypoxia. Inhibition of VEGF and VEGF receptor-mediated signaling would improve oxygen perfusion in COVID-19.13–17

Bevacizumab is a recombinant humanized monoclonal antibody that inhibits VEGF-A protein and thereby blocks angiogenesis. It was approved in 2004 for combination therapy with standard chemotherapy for metastatic colon cancer. Since then, it has been approved for treating renal cancer, ovarian cancer, lung cancer, and glioblastoma multiforme of the brain.18,19 The single-arm trial that evaluated the efficacy of bevacizumab in patients with COVID-19 showed promising results in improving oxygenation and shortening oxygen support duration. However, real-life data are limited on the effectiveness of bevacizumab in patients with COVID-19. The aim of this study was to assess the effectiveness of bevacizumab in COVID-19 pneumonia among critically ill patients.

2. Methods 2.1. Study design and participants

This is a retrospective, single-center, observational study performed in the intensive care unit, Department of Critical Care Medicine, PSG Hospitals, Tamil Nadu, India, between February 2021 and February 2022 on patients with severe COVID-19 pneumonia. Data of patients who received intensive care unit (ICU) care were derived from electronic health records.

The study inclusion criteria were adult patients aged 18 years or older with COVID-19, confirmed by reverse transcription-polymerase chain reaction, who were admitted to ICU during the study period. Eligible patients had COVID-19–associated pneumonia, defined as at least one of the following: peripheral blood oxygen saturation (SaO2) of less than 93% in room air, presence of respiratory rate of 30 or more breaths per minute, PF ratio (a ratio of arterial oxygen partial pressure [PaO2] to fractional inspired oxygen [FiO2]) of less than or equal to 200 mm Hg in room air, and lung infiltrates of more than 50% (radiologically—high resolution computed tomography [HRCT]/chest x-ray) within 24–48 hours of hospital admission.

Exclusion criteria were severe renal and hepatic impairment, gastrointestinal perforation, gastrointestinal fistula, uncontrolled hypertension, heart failure (NYHA class II or higher), patient with active bleeding, patients who underwent major surgery within 28 days, or pregnant and breastfeeding women.

This study was approved by the institutional human ethical committee (PSG/IHEC/2021/Appr/EXP/173) with a waiver of informed consent.

2.2. Procedures

All patients in the intensive care unit received standard-of-care treatment according to the hospital policy. Standard-of-care treatment included methylprednisolone (1 mg/kg once every 24 hours for 7 days), remdesivir (200 mg on day 1 followed by 100 mg once every 24 hours for 10 days in mechanically ventilated patients and 5 days in other patients), and enoxaparin 1 mg/kg once every 12 hours.

Bevacizumab was administered intravenously at 7.5 mg/kg along with standard care in a non–randomly selected subset of patients. It was considered in patients with evidence of ARDS within 72 hours of worsening of oxygenation. However, the final decision to use bevacizumab was at the discretion of the treating physician considering the affordability and willingness of patient attenders.

The severity of the disease was assessed radiologically using the severity score proposed by Warren et al.20 A score of 0–4 was given to each lung based on the extend of lung involvement (score 0 = no involvement, 1 ≤ 25% of lung infection, 2 = 25%–50% of lung infection, 4 ≥ 75% of lung infection). A total severity score was calculated by summing the scores of both lungs.

2.3. Outcomes

The primary outcome measure was ICU-related mortality. The secondary outcome measures were change in clinical status of patients measured by the WHO 7-category Ordinary Scale, duration of ICU stay, the incidence of thrombotic events, secondary infections, changes in PF ratio, and radiological improvement measured by using total severity score.

2.4. Statistical analysis

The baseline characteristics of patients treated with bevacizumab were compared with those treated with standard of care alone. Continuous variables were summarized using median (IQR- Interquartile Range) and compared by using the Mann-Whitney U test. Categorical variables were expressed by frequency (%) and compared by using the Fisher exact test. Statistical analysis was performed using SPSS, version 26. The effect on the primary outcome and secondary outcomes such as mortality up to 28 days, clinical status at day 28, the incidence of thrombotic events, and secondary infections were represented by odds ratio. Changes in PF ratio and radiological changes in the bevacizumab group were compared by using the paired t test.

3. Results

A total of 111 patients were recruited in this study, of whom 29 patients received bevacizumab along with the standard of care. Table 1 summarizes the baseline characteristics and investigations of the patients. The median age of the bevacizumab-treated patients was 52.8 (25–80) years, and 26 (89.6%) were men. In the standard-of-care group, 60 (73.1%) were male and 22 (26.8%) were female. The median age of the standard-of-care group was 59.04 (20–83) years. The most common comorbidities were diabetes and hypertension. Fever, cough, and breathlessness were the presenting symptoms in most of the patients.

Table 1 - Baseline characteristics and investigations of patients Bevacizumab group (n = 29) Standard-of-care group (n = 82) P Age 52.8 (25–80) 54.9 (20–83) .5 Sex .07  Male 26 (89.6%) 60 (73.1%)  Female 3 (10.3%) 22 (26.8%) Comorbidities .8  Yes 19 (65.5%) 55 (67.07%)  No 10 (34.4%) 27 (32.9%) Comorbidity count  0 10 (34.4%) 27 (32.9%)  1 10 (34.4%) 25 (30.4%)  2 6 (20.6%) 22 (26.8%)  ≥3 3 (10.3%) 8 (9.7%) Diabetes 8 (27.5%) 20 (24.3.4%) .62 Hypertension 7 (24.1%) 17 (20.7%) .79 Obstructive airway disease 2 (6.8%) 5 (6.0%) 1.0 Symptoms  Fever 20 (68.9%) 46 (56.09%) .27  Cough 19 (65.5%) 57 (69.5%) .81  Breathlessness 10 (34.4%) 32 (39.02%) .82 Baseline WHO 7-category Ordinal Scale* 4.93 (4–6) 4.92 (4–6) 1.0  4 11 (37.9%) 29 (35.3%)  5 9 (31.03%) 30 (36.5%)  6 9 (31.03%) 23 (28.04%) Inflammatory markers  Ferritin (ng/mL) 799.7 (46.5–2000) 786.9 (47–2000) .9  Interleukin-6 (pg/mL) 361 (18.5–5000) 366.2 (9–5000) .11  LDH (U/L) 512.1 (200–1188) 570.09 (155–1702) .25  WBC (mm3) 9358.6 (4100–21,000) 9989 (1100–30,800) .99 Disease duration  Days from symptom onset to hospitalization 5.13 (1–21) 6.59 (1–21) .9  Days from symptom onset to ICU admission 8 (1–21) 7.8 (1–21) .35 SOFA score 3 (1–12) 3 (1–12) 1.0 Baseline PF ratio (PaO2/FiO2) 156.3 (45–200) 150.89 (44.3–200) .09  <100 9 (31.03%) 21 (25.6%)  100–200 20 (68.9%) 61 (74.3%)

BMI, body mass index; FiO2, fraction of inspired oxygen; ICU, intensive care unit; LDH, lactate dehydrogenase; PaO2, partial pressure of oxygen; SOFA, Sequential Organ Failure Assessment, WHO, World Health Organization.

*4: hospitalized, no oxygen therapy, but requiring medical care; 5: hospitalized, any supplemental oxygen; 6: hospitalized, requiring NIV (noninvasive ventilation) or HFNC (high-flow nasal cannula).

The median time from onset of symptoms to hospitalization was 5.1 (1–21) days in bevacizumab-treated patients and 6.5 (1–21) days in the standard-of-care group. Bevacizumab was administered for a median of 9.4 (4–24) days from the onset of symptoms, 5.1 (1–18) days from the day of hospitalization, and 2.2 (1–3) days from the day of ICU admission.

In the bevacizumab group, 13 (44.8%) of 29 patients died in ICU, and in the standard-of-care group, 37 (45.1%) of 82 patients died. However, bevacizumab was not associated with significant difference in mortality up to 28 days (odds ratio 0.98, 95% confidence interval 0.42–2.31, P = .97). Primary and secondary outcomes are summarized in Table 2.

Table 2 - Primary and secondary outcomes Outcome Bevacizumab group (n = 29) Standard-of-care group (n = 82) Effect estimate Effect size (95% CI) P Mortality up to 28 days 13 (44.8%) 37 (45.1%) OR 0.98 (0.42–2.31) .97 Clinical status at day 28 OR 1–6 vs 7–8 1.02 (0.44–2.4) .94 1: Not admitted to hospital, no limitation on activities 11 (37.9%) 29 (35.3) 2: Ambulatory, limitation of activities, home oxygen requirement 3 (10.3%) 9 (10.9%) 3: Hospitalized, no oxygen therapy, not requiring medical care 0 0 4: Hospitalized, no oxygen therapy, but requiring medical care 0 0 5: Hospitalized, any supplemental oxygen 0 2 (2.4%) 6: Hospitalized, requiring NIV or HFNC 1 (3.4%) 3 (3.6%) 7: Hospitalized, requiring IMV or ECMO 1 (3.4%) 2 (2.4%) 8: Death 13 (44.8%) 37 (45.1%) Secondary infections* 9 (31.03%) 24 (29.2%) OR 1.08 (0.43–2.7) 0.85 Thrombotic events 2 (6.8%) 6 (7.3%) OR 0.93 (0.17–4.9) 0.94

ECMO, extracorporeal membrane oxygenation; HFNC, high-flow nasal cannula; IMV, invasive mechanical ventilation; NIV, noninvasive ventilation; OR, odds ratio.

*Bevacizumab group: bloodstream (n = 6), respiratory (n = 4), and urine (n = 2). Two patients had bacteremia and urinary tract infection. One patient had bacteremia, respiratory infection, and urinary tract infection. Standard-of-care group: bloodstream (n = 17) and respiratory (n = 11). Four patients had bacteremia, respiratory infection, and urinary tract infection.

The difference in clinical status assessed using the WHO 7-category Ordinary Scale at 28 days between the bevacizumab group and the standard-of-care group was not statistically significant (odds ratio 1.02, 95% confidence interval 0.44–2.4, P = .94). On day 28, 2 patients (6.8%) in the bevacizumab group and 7 patients (8.5%) in the standard-of-care group had supplemental oxygen requirements. Ventilatory support status of patients from the first day of bevacizumab therapy through 28 days of follow-up is illustrated in Figure 1.

Figure 1.:

Ventilatory support status of patients from the first day of bevacizumab therapy through the 28-day follow-up. BIPAP, bilevel positive airway pressure; HFNC, high-flow nasal cannula; IMV, invasive mechanical ventilation; NIV, noninvasive ventilation; NRM, nonrebreather mask.

Secondary infections occurred in 9 patients (31.03%) in the bevacizumab group and 24 patients (29.2%) in the standard-of-care group. At week 4, there was no statistical difference in the rate of infections between two groups (odds ratio 1.08, 95% confidence interval 0.43–2.7, P = .85). Two patients (6.8%) in the bevacizumab group and 6 patients (7.3%) in the standard-of-care group developed thrombotic events during the hospital stay (odds ratio 0.93, 95% confidence interval 0.17–4.9, P = .94). No significant difference was found in the duration of ICU stay between the two groups (9.9 days in the bevacizumab group and 9.8 days in the standard-of-care group, P = .91). Two bevacizumab-treated patients experienced hypertension within 24 hours of drug administration, 2 patients developed acute kidney injury, and 1 had an injection site pain. No hypersensitivity reactions were reported.

Bevacizumab-treated patients showed a statistically significant improvement in PF ratio within 48 hours of drug administration. Radiological severity score reduced markedly in 14 patients, remained constant in 8 patients, and increased in 7 patients at 3–7 days after bevacizumab administration (Table 3).

Table 3 - Changes in PF ratio and x-ray severity score in the bevacizumab group Before bevacizumab After bevacizumab P PF ratio 77.15 110.71* .000 Radiological severity score 6.1 5.0† .03

*48 hours after bevacizumab.

†3–7 days after bevacizumab.

4. Discussion

This is a single-center, observational study performed in 111 patients with COVID-19 pneumonia admitted to the medical intensive care unit, of whom 29 were treated with bevacizumab along with standard of care. The use of angiogenesis inhibitor bevacizumab was not associated with a statistically significant reduction in mortality and improvement in clinical outcome assessed by the WHO 7-level Ordinal Scale at 28 days. As per the multicenter trial conducted in China and Italy, treatment with bevacizumab along with the standard of care shortened the duration of oxygen support. Bevacizumab 7.5mg/kg single-dose administration improved the oxygen support status in 92% of patients during 28 days of follow-up, whereas in the control group, the improvement rate was only 62%. No death was reported after bevacizumab therapy in the 28-day follow-up trial.17

As per randomized controlled trials, the bevacizumab therapy was associated with an increased risk of thromboembolic events in patients with cancer.21 The proposed mechanisms for thrombosis associated with bevacizumab include the following: (1) VEGF inhibition would decrease the production of prostacyclin and nitric oxide, leading to increased blood viscosity and platelet aggregation; (2) anti-VEGF activity damages the endothelial walls of blood vessels and exposes subendothelial lipids by thrombosis formulation; and (3) hindering the anti-inflammatory effect of VEGF would increase vascular inflammation and cause thrombus development.22–25 Thrombotic events reported in bevacizumab-treated patients and in the standard-of-care group were 2 (6.8%) and 6 (7.3%), respectively. Thromboembolic complications of COVID-19 are common, especially in critically ill patients, and thrombotic events are mainly attributed to a COVID-19–associated hypercoagulable state.26,27

Evidence suggests that there were elevated plasma VEGF levels in severe COVID-19 pneumonia. ARDS-driven hypoxia induces VEGF expression, resulting in increased vascular permeability and pulmonary edema, which further worsens tissue hypoxia. Bevacizumab alleviates clinical symptoms in patients with COVID-19 by improving oxygen perfusion and through its anti-inflammatory action.13–15 Radiological improvement was shown by bevacizumab-treated patients within 3–7 days of drug administration. Total severity scores were reduced in patients treated with bevacizumab when compared with baseline. The PF ratio of bevacizumab-treated patients markedly increased within 48 hours of drug administration. This result was similar to the single-arm multicenter trial. Improvement in PF ratio at days 1 and 7 after bevacizumab administration in trial patients might reflect antivascular leakiness effect.17

Although the treatment with bevacizumab provided radiological improvement and improvement in PF ratio, it did not show superiority to standard of care in reducing mortality and improving clinical outcomes. Various mechanisms studied in researches that may account for the nonsuperior effectiveness of bevacizumab are as follows: VEGF promotes the expression of endothelial cell antiapoptotic proteins and blocks apoptosis of endothelial cells. Inhibition of VEGFR may result in alveolar septal cell apoptosis and emphysema. VEGF genetic polymorphism contributes to the development of acute lung injury or ARDS.28–31 There may be interindividual variations in plasma VEGF levels and genetic variation in the VEGF pathway. Studies showed that the presence of genetic polymorphism was associated with a high risk of pulmonary complications, including acute lung injury or ARDS.32–35 Hemodynamic studies have shown that VEGF is a powerful vasodilator. Inhibition of VEGF receptors may cause severe pulmonary hypertension.36

Our study has some limitations. It is a retrospective observational study and not a randomized comparison. The decision on bevacizumab initiation was taken by the treating physician based on clinical and laboratory parameters of patients, drug availability, and affordability of patient attenders. Other limitations include small sample size, short-term follow-up, and lack of correlation with plasma VEGF levels. Follow-up HRCT was performed only in few patients, and hence, radiological assessments of patients were performed by using either HRCT or chest x-ray.

The definitive role of VEGF in acute lung injury or ARDS remains inconspicuous because of the pleiotropic effects of VEGF in the human body. VEGF signaling pathways in various stages of ARDS should be further explored, and a greater understanding of VEGF regulation and anti-VEGF therapies is required. Clinical trials are inevitable to establish the role of bevacizumab in COVID-19. Insight knowledge on the role of angiogenic and antiangiogenic factors in acute lung injury is necessary before considering bevacizumab as an immunomodulating treatment option in COVID-19.

5. Conclusion

Bevacizumab administration in patients with severe COVID-19 pneumonia requiring intensive care unit care was not superior to standard care alone in reducing mortality and improving clinical outcomes at day 28.

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