COVID-19 severity in patients with chronic lymphocytic leukemia treated with venetoclax: a single-center observational cohort study

Patients with chronic lymphocytic leukemia (CLL) are at high risk of developing severe COVID-19. The present study was undertaken to elucidate COVID-19 related morbidity and mortality in CLL patients treated with venetoclax. We present a single-center study of 108 patients with small lymphocytic lymphoma or CLL treated with venetoclax. Primary outcome was 30-day COVID-19 mortality. Secondary outcomes included COVID-19 severity and hospitalization rate. Forty-eight (44%) patients had PCR-verified SARS-COV-2 between March 2020 and January 2023. Thirty-six patients (75%) presented with asymptomatic/mild COVID-19 and 12 (25%) with severe/critical disease. The hospitalization rate was 46% with a 30-day mortality rate of only 4% and severe comorbidities as the primary cause of death. COVID-19 severity and mortality were similar before and during the Omicron era. High CIRS-scores (P < 0.02) and thrombocytopenia (P < 0.01) were more frequent in patients with severe/critical disease. In real-world data, most venetoclax treated patients presented with mild COVID-19. Hospitalization and mortality rates were low compared to data of general CLL populations. Our data indicate that venetoclax was a safe treatment option for CLL patients during the pandemic.


Introduction
Chronic lymphocytic leukemia (CLL) patients diagnosed with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) are at high risk of hospitalization and death [1].Risk factors for severe coronavirus disease 2019 (COVID-19) infections including hypogammaglobulinemia, B and T-cell defects, CD4 + lymphopenia, neutropenia, innate immune dysfunction, treatment with anti-CD20 targeting agents, and age-related medical conditions are often toxicity profile in patients with CLL.However, among the most common grade 3/4 adverse events are neutropenia, febrile neutropenia, pneumonia, and sepsis [12].There are few available data on COVID-19 in patients receiving venetoclax-based treatments.A study has suggested that venetoclax blocks the interaction between the SARS-CoV-2 spike (S) glycoprotein and the angiotensin-converting enzyme 2 receptor through spike protein degradation [13].Venetoclax may therefore exhibit protective mechanisms against COVID-19 by inhibiting viral nucleic acid sequences to enter the host cell.In agreement with these observations, a recent study reported only two (7%) hospitalizations and/or deaths after contracting COVID-19 among 27 CLL patients receiving venetoclax, and no events were recorded in patients receiving nirmatrelvir plus ritonavir [14].Other studies have proposed that treatment with venetoclax is correlated with higher immunogenicity and seroconversion rates after COVID-19 booster vaccines compared to ibrutinib [15].
Here we present real-world data of the frequency, severity and mortality of COVID-19 in an observational singlecenter study of CLL and SLL patients consecutively treated with venetoclax during the COVID-19 pandemic.Our data were collected during both the pre-and post-vaccine era as well as the pre-Omicron and Omicron wave.

Patients
Patients diagnosed with CLL or SLL and treated with venetoclax were included in an observational single-institution study.Patients were identified in the electronic patient health record platform (EPIC).Venetoclax treatment was initiated between April 2017 and December 2022.Patients were treated with standard ramp up and steady state dose of venetoclax.Dose level and duration of treatment varied depending on tolerability and efficacy.

SARS-CoV-2 testing
COVID-19 was defined as a positive SARS-CoV-2 reverse transcription polymerase chain reaction (RT-PCR) test.Local guidelines at our institution included testing of all hematological patients upon admission or out-patient visits, and mass screening twice a week during surges.A high frequency of positive SARS-CoV-2 samples were whole genome sequenced and the information on SARS-CoV-2 including sublineage was retrieved from the Danish national microbiology database (https://www.covid19genomics.dk/nextstrain) [16].We used a cut-off point corresponding to January 2022 to compare patients with COVID-19 before and during the Omicron era.The Omicron subvariants were dominating in Denmark since January 2022, including the most frequent variant B.1.1.529[4].Prior to this, Delta B.1.617.2 (original Delta variant) and Delta AY.4.2 (Delta plus variant) were the dominating variants.The Danish COVID-19 Genome Consortium (DCGC) provided data on the SARS-CoV-2 subvariants.

Statistics
All data were registered in a local secured research database (REDCap).Statistical analyses were performed in R software (version 4.2.3).Clinical variables were summarized using descriptive statistics.Categorical variables are presented as numbers and percentages and continuous variables as median and ranges or interquartile ranges (IQR).Categorical variables were analyzed by Fisher's exact test.30-day COVID-19 mortality rate was estimated as the proportion alive 30 days after verified SARS-CoV-2 infection.The hospitalization rate was measured as the proportion of patients with hospitalization of minimum 24-hours duration within 30-days from a positive PCR test.ICU admission rate was calculated as the proportion of patients admitted to an ICU within one month of verified infection.Time-toevent analyses were performed using Kaplan-Meier plots and log-rank test was used for the comparison of survival in different groups.The level of statistical significance was defined as P < 0.05.

Patient characteristics
We identified 112 patients with CLL or SLL treated with venetoclax.Four patients with COVID-19 infection prior to initiation of venetoclax were excluded.Of the remaining 108 patients, 48 (44%) patients had a positive SARS-CoV-2 PCR test after initiation of venetoclax treatment.Flowchart of clinical subgroups in the study cohort is provided in Fig. 1.We identified the SARS-CoV-2 variant in 27/48 (56%) patients, with 6 cases of B.1.617.2 (Delta-variant) and 21 cases of B.1.1.529(Omicron-variant).The distribution of SARS-CoV-2 variants was in accordance with our cut-off point with a case of B.1.617.2 (Delta-variant) detected in 2022 as the only exception.Most patients (98%) had received the recommended number of vaccines in Denmark with 92% being vaccinated with ≥ 4 doses.Sufficient vaccine antibody response measured with enzyme-linked immunosorbent assay (ELISA) was observed in 15/32 (47%).
COVID-19 infection was detected during ongoing venetoclax treatment in 29/48 (60%) and after discontinuation of venetoclax in 19/48 (40%).In 19/29 (66%) patients diagnosed with COVID-19 infection during venetoclax treatment, venetoclax was continued without changing the current dose level.In four (14%) patients, the decision was made to temporarily discontinue venetoclax treatment for a duration of 2 to 60 days.In another four (14%) patients, venetoclax was permanently discontinued when a sufficient response to treatment had already been achieved and termination of venetoclax was expected in a short period of time regardless of the appearance of the infection.The two remaining patients died shortly after discontinuation of venetoclax from causes regarded as non-related to COVID-19 infection.The hospitalization rate among patients with ongoing venetoclax treatment at the time of COVID-19 diagnosis was 48%.

COVID-19 severity and mortality
Most patients presented with mild symptoms or asymptomatic COVID-19 disease (75%) and the hospitalization rate at 30 days was 46%.No significant differences in severity were detected between patients with COVID-19 during and after the pre-Omicron era (Table 2).Three patients (6%) experienced reactivation of the same SARS-CoV-2 origin within 2 months after a negative PCR test.Two patients experienced reactivation with the B.1.1.539-variant(Omicron type) and one patient had reactivation with the B.1.617-variant(Delta type) with all 3 cases of reactivation being symptomatic.Distribution of clinical characteristics at initiation of venetoclax between patients with asymptomatic/mild disease and patients with severe/critical disease is shown in Table 3.Only thrombocytopenia and high CIRS-score were found with a significantly higher frequency in patients with severe/ critical disease.Treatments of the COVID-19 infection are shown in Table 4.The antiviral treatment was given according to Danish national guidelines.Patients with ongoing venetoclax treatment more frequently received treatments with preemptive anti-SARS-Cov-2 monoclonal antibodies (24/29 (83%) and 10/19 (53%), respectively; P = 0.04), other antiviral drugs (13/29 (45%) and 2/19 (11%), respectively; P = 0.02), and antibiotics (15/29 (52%) and 6/19 (32%), respectively; P < 0.01).
Only 2/48 (4%) patients died within 30 days of a positive SARS-CoV-2 PCR test.Both deaths were regarded as non-related to COVID-19 infection.In one case the primary cause of death was given as pulmonary cancer and in the other case as Richter's transformation.No additional deaths were observed 90 days after a positive SARS-CoV-2 PCR test.

Secondary infections
In the cohort of patients treated with venetoclax (n = 48), secondary infections were observed in 17 (35%) patients while 21 (44%) of the patients were treated with antibiotics.The infections were either verified clinically (e.g., clinical examination or pulmonary infiltrates on imaging) or by microbiological detection of pathogens.Most cases were pneumonias, upper respiratory or urinary tract infections.A  5.  show similar hospitalization rates but notable higher ICU admission rates at 19-22% [6,7].Routine PCR testing at our center could have made early detection and intervention with antiviral antibodies more likely.This may have contributed to the low ICU admission rate.
The 30-day mortality rate was found to be lower than expected with only two deaths (4%), both occurring in patients with severe comorbidities as the primary cause of death.Higher mortality rates of 19-33% among CLL patients have been reported in other studies [3,18].In a recent large clinical trial of first-line venetoclax combinations, COVID-19 was detected in a small subgroup with 4/45 (9%) deaths in venetoclax-treated patients with COVID-19 and 2/10 (20%) deaths in chemoimmunotherapy-treated patients [11].These mortality rates are higher compared to our data, but the study In our study, patients in ongoing venetoclax treatment required more intensive treatment with antiviral antibodies, antiviral drugs and antibiotics compared to patients with COVID-19 after discontinuation of venetoclax.In general, infections are relatively common in patients treated with venetoclax.Multiple studies had shown grade 3-4 infection rates at estimated 20% in patients during treatment, most frequently pneumonia, sepsis or febrile neutropenia [9,19].Furthermore, cytopenia including neutropenia are one of the most common grade 3-4 adverse events related to venetoclax [20].However, our real-life data has shown that infections with COVID-19 generally has a mild and manageable course in venetoclax treated patients and a very low mortality mostly related to accompanying comorbidities.
In vitro studies investigated the ability of venetoclax to bind and degrade the spike protein in SARS-CoV-2 [14,21].The pharmacological properties and the abilities to interact with the spike protein of SARS-CoV-2 were investigated.Venetoclax was able to degrade the expression of the spike protein and blocking the virus' interaction with the ACE-2 receptor.These findings indicate that blocking the interaction between the spike protein and the ACE-2 receptor potentially prevent the virus' entry into the host cell.Venetoclax may therefore express some properties with a protective effect against severe COVID-19 disease.
The present study has some limitations, including a small sample size, missing data on some SARS-COV-2 variants and partly missing data on antibody levels.The size of the cohort did not allow more extended analyses with most data being descriptively presented.However, our data clearly suggest that CLL patients who are treated with venetoclax generally present with manageable COVID-19 and a low

Fig. 1 3
Fig. 1 Flow chart with stratification of the study cohort Data were collected from electronic patient records between August 2022 and January 2023.Baseline characteristics and clinical outcomes were recorded including severity and mortality of COVID-19 infections.The primary outcome of the study was 30-day COVID-19 mortality rate, defined by death within 30 days from positive PCR test.

Table 1
Clinical characteristics at initiation of venetoclax treatment

Table 5
Secondary infections after COVID-19 (within 2 months from positive PCR test)