508. Nirmatrelvir/ritonavir use among patients with cancer and COVID-19 is associated with improved clinical outcomes: Single-institution case-control study
Authors: Arvanitis Panos , Vieira Kendra , Warner Jeremy L , Farmakiotis Dimitrios 
Published: November 2023

Abstract

Background
Patients with cancer are at increased risk for severe and lethal COVID-19, compared to the general population. Currently, with no anti-spike monoclonal antibodies available against circulating variants of SARS-CoV-2, the logistic limitations of outpatient remdesivir infusions, and lack of efficacy of molnupiravir in vaccinated patients, nirmatrelvir/ritonavir (Paxlovid™) is the only effective oral therapy for outpatient use against COVID-19. However, its efficacy specifically in immunocompromised patients, including patients with cancer, has not been adequately studied.

Methods
In this pilot analysis, we retrospectively studied the records of patients with history of or active cancer at Brown University-affiliated hospitals diagnosed with SARS-CoV-2 after Emergency Use Authorization (EUA, 2021-12-22) of Paxlovid™, and until 2022-07-21. Patients not meeting EUA criteria or receiving other outpatient antivirals were excluded (Figure 1). The primary outcome was 90-day COVID-19-attributed mortality, with 90-day all-cause mortality and hospitalization as secondary outcomes. Patients who died within 90 days from other causes were excluded from COVID-19-attributed mortality analyses.
Figure 1.
Flow diagram illustrating patient selection.

Results
33 of 85 eligible patients were excluded (Figure 1). Of the 52 remaining, 26 received Paxlovid™. Baseline demographic and clinical characteristics were well-balanced between the two groups (Table 1). 50% were male, one was Black, five were Hispanic (10%); median age was 68 (interquartile range [IQR] 56-77) years; most patients (61.5%) had received 3 or more vaccine doses prior to infection. Paxlovid™ use was associated with numerically lower all-cause mortality rate (8% vs. 23%), and significantly lower rates of 90-day COVID-19-attributed mortality (0% vs. 19%, p=0.03; Log-rank p&lt; 0.01, Figure 2), and hospitalization (27% vs. 65%, p&lt; 0.01).
Table 1.
Baseline characteristics and clinical outcomes.
Figure 2.
Kaplan-Meier survival curves.

Conclusion
Paxlovid™ use was associated with a strong signal for improved clinical outcomes among patients with cancer and COVID-19, compared to similar contemporary controls, most of whom were fully vaccinated. Larger studies of Paxlovid™ use and efficacy in high-risk patients with cancer and other immunocompromised individuals are needed and ongoing.

Disclosures
Panos Arvanitis, MS, NIH: Grant/Research Support|NIH: Brown University Summer Assistantship program and from the Brown Emerging Infectious Disease Scholars (EIDS) (5R25AI140490) Jeremy L. Warner, MD, MS, AACR: Grant/Research Support|Flatiron Health: Grant/Research Support|Melax Tech: Advisor/Consultant|NIH: Grant/Research Support|Roche: Advisor/Consultant|Westat: Advisor/Consultant Dimitrios Farmakiotis, M.D., Astellas: Grant/Research Support|Merck: Grant/Research Support|Viracor: Advisor/Consultant|Viracor: Grant/Research Support