Detection Rate of SARS-COV2 Antibodies After COVID-19 in Patients with Cancer

Results from an analysis published in Annals of Oncology, which included both patients with cancer and healthcare workers at Centre Léon Bérard in Lyon, France, demonstrated that patients with cancer had a significantly lower detection rate of SARS-COV2 antibodies 15 days or later after coronavirus disease 2019 (COVID-19) symptoms and RT-PCR-positive test than healthcare workers.¹

“[Patients with cancer] had a significantly lower detection rate of SARS-COV2 antibodies 15 days or later after symptoms and RT-PCR+ testing,” the study authors wrote. “Anti-SARS-COV2 [antibodies] were more often undetectable in patients receiving cancer treatments in the month prior to testing.”

In this study, researchers retrospectively analyzed patients with cancer presenting with a suspicion of COVID-19 from March 1, 2020 to April 16, 2020 as part of an Institutional Review Board approved clinical trial, as well as a series of healthcare workers as part of a voluntary testing procedure. 

COVID-19 is diagnosed by detection of the SARS-COV2 virus in nasopharyngeal samples by RT-PCR.² Moreover, most patients who have been infected develop antibodies against SARS-COV2 proteins.

Overall, 85 patients with cancer were tested with both SARS-nCoV2 RT-PCR on nasopharyngeal samples and a point of care antibody diagnostic call Toda Coronadiag. Coronadiag is a rapid lateral flow immunoassay (LFIA) which can provide results in 10 minutes using a finger-pricked blood sample. This test was performed 15 days or more after a positive RT-PCR or COVID-19 symptoms. 

Ultimately, 10 of 85 (12%) patients with cancer had documented SARS-CoV2 on RT-PCR, and 5 (6%) had a positive antibody detection test. Additionally, 3 of the 10 (30%) RT-PCR-confirmed infected patients had detectable antibodies against SARS-COV2 15 days after the clinical start of the infection and 2 of the 75 (2.3%) remaining patients with cancer screening negative for RT-PCR had detectable SARS-COV2 IgG.

Similarly, all 244 healthcare workers were tested with the LFIA test, including 14 with a RT-PCR-documented SARS-COV2 infection. Of these, 10 (71%) RT-PCR-confirmed infections had detectable antibodies 15 days or later after clinical symptoms. Further, 3 of the remaining 230 (1.3%) healthcare workers had detectable antibodies, but negative tests for RT-PCR performed at the same time; 2 of these reported possible COVID-19 symptoms in the previous week. 

Given these collective findings, the researchers found that the rate of seroconversion 15 days after SARS-COV2 infection confirmed by RT-PCR was significantly lower in patients with cancer than in healthcare workers (30% vs 71%, P = 0.04). 

“Importantly, 6 of the 7 serodiagnostic-negative cancer patients had received cytotoxic therapy or major surgical intervention in the previous 4 weeks, compared to none of the 5 remaining patients (P = 0.003),” the authors wrote. “None of these patients died.”

According to the researchers, additional studies will be necessary to confirm whether immune response to the virus is influenced by recent cancer treatments.

References:

1. Solodky ML, Galvez C, Russias B, et al. Lower detection rates of SARS-COV1 antibodies in cancer patients vs healthcare workers after symptomatic COVID-19. Annals of Oncology. doi:10.1016/j.annonc.2020.04.475. 

2. Lower Antibodies Rate in Cancer Patients After Symptomatic COVID-19 Than in Healthcare Workers [news release]. Lyon, France. Published May 11, 2020. esmo.org/oncology-news/lower-antibodies-rate-in-cancer-patients-after-symptomatic-covid-19-than-in-healthcare-workers. Accessed May 12, 2020.