A total of 466 patients accessing the U01H and H04 of Ospedale Policlinico San Martino Cancer Center were screened in the period between April 14th and June 23rd 2020 with the inclusion and exclusion criteria outlined above before undergoing the first SARS-CoV-2 serology, which was performed on 446 individuals. Of these 146 were affected by breast cancer, 103 by colorectal cancer, 42 by prostate cancer, 28 by pancreatic cancer, 25 by ovarian cancer, 18 by renal cancer, 17 by GIST, 14 by gastric cancer, 12 by hepatobiliary cancer, 11 by lung cancer, 8 by sarcoma, 5 by endometrial cancer, 4 by cervical cancer, 3 by esophageal cancer, 3 by urothelial cancer, and 7 by other neoplasms. Twenty patients were ruled out (6 because of COVID-19 suggestive symptoms occurred in the period preceding the date of enrollment, 6 because of hematologic malignancy, 1 because of previous NPS-confirmed SARS-CoV-2 detection, 7 because of antineoplastic therapy interruption or prosecution in domiciliary regimen).
Patients’ age ranged between 27 and 90 (9 patients under 40, 30 patients between 40 and 50, 92 patients between 50 and 60, 139 between 60 and 70, 135 between 70 and 80, and 40 between 80 and 90)
Of the recruited patients, 397 underwent at least two serologies, 312 underwent at least three serologies, and 122 underwent four serologies. Patients detected as IgM and/or IgG positive were excluded from the total count of the following tests.
SARS-CoV-2 seroprevalence decreases after lockdown measures in oncologic outpatients.
A total of 14 patients (3.14 %) tested positive for at least one SARS-CoV-2 immunoglobulin in the period between April 14th and 23th August 2020. See Tab.1 for serology results in the accrual and follow-up phases.
In the first month of the accrual, from April 14th to May 17th, SARS-CoV-2 serology was performed on 270 patients, of which 48 underwent a second serology in the same period. SARS-CoV-2 immunoglobulins were detected in 7 patients (2.59 % of patients, 2.20 % of serologies), of which 2 positive for IgM (1 weakly positive), 3 for IgG (1 weakly positive), 2 for both IgM and IgG.
In the second month of the accrual, from May 18th to June 23rd, SARS-CoV-2 serology was performed on 390 patients, of which 134 underwent a second serology in the same period. SARS-CoV-2 immunoglobulins were detected in 6 patients (1.54 % of patients, 1.14% of serologies), of which 3 positive for IgM (1 weakly positive) and 3 for IgG (of which 1 weakly positive).
In the third month of the study, from June 24th to July 23rd, SARS-CoV-2 serology was performed on 261 patients, of which 18 underwent a second serology in the same period. SARS-CoV-2 IgGs were detected in 1 patient (0.38 % of patients, 0.36% of serologies).
In the fourth month of the study, from July 24th to August 23rd, SARS-CoV-2 serology was performed on 97 patients, of which 1 underwent a second serology in the same period. No SARS-CoV-2 immunoglobulins were detected in this period.
NPS was performed after serology on all 7 patients detected as positive for SARS-CoV-2 IgM. None of the NPS detected viral RNA.
COVID-19 elicits a multiform serological response in patients affected by solid tumors
Of the 11 patients detected as positive for SARS-CoV-2 immunoglobulins at the first serology two underwent three follow-up serologies, six underwent two follow-up serologies, and two underwent one follow-up serology (Tab.1). Two patients did not undergo follow-up serologies.
UPN8 maintained the positivity for both antibodies across all tests, while UPN5 lost the IgM positivity at the fourth serology. Two patients (UPN4, UPN11) detected as IgG positive at the first serology maintained the IgG positivity at the third test. Four IgM + patients (UPN1, UPN2, UPN10, UPN12) did not undergo IgG seroconversion. Among those patients who resulted negative at the first serology, UPN3 tested weakly positive for SARS-CoV-2 IgM only at the second serology, presumably a false positive result, while UPN13 tested positive for SARS-CoV-2 IgG at the second and third serology.
PBMCs transcriptomic features assessed in asymptomatic patients affected by solid tumor with serological evidence of SARS-Cov2 are consistent with a previous viral infection.
Blood samples (3 ml each) were collected from two SARS-CoV-2 IgM positive patients (UPN 1 and UPN 8) affected by advanced breast cancer (stage IV and IIIB, respectively) at three different time points (Baseline, at 2 months, at 7 months). Both patients underwent a further serology at the moment of the last blood collection. One patient showed IgM seroconversion at baseline, and never developed IgG, albeit maintaining IgM positivity at all time points, whereas the other showed seroconversion to IgG with disappearance of IgM at the last blood draw. Neither tested positive for SARS-CoV-2 NPS at any time point. Both were consistently asymptomatic throughout the collection period.
The evaluation of PBMC transcriptomic signatures over time showed a pattern consistent with immune dysregulation. Of particular interest, we observed in both patients a decreasing monotonic profile in the GSE13485 transcriptomic signature, reported as downregulated in PBMCs of subjects vaccinated with the Yellow Fever vaccine YF-17D in PBMCs at three days from vaccination compared to 21 days (See Figure 2A). While apparently contradictory with our findings, this behavior is consistent with an initial perturbation of the signature at an unspecified time before the initial finding, which may have resulted in high levels for YF-17D at baseline assessment, followed by its decrease, as time from putative viral infection passed by. YF-17D signature includes fibroblast growth factor 23 (FGF23) and prostaglandin I2 synthase (PTGIS), genes upregulated by interleukin-6 (IL6) at the onset of COVID-19 . IL6 has indeed been recently shown to be highly overexpressed in such disease, possibly acting as a therapeutic target to prevent severe symptoms . Likewise, genes pertaining to chemokine-mediated signaling pathways such as CCL20, CXCL12, and CXCR1, were found overexpressed at the first blood draw and gradually decreased over time, as did several genes of the chemokine-chemokine receptor KEGG pathway (p-value = 0.018, see Supplementary Figure 1), such as CXCR6, IL4, LIF, OSM, IL6ST, IL12RB2 – part of the Interleukin 6/12-like signaling. All these transcripts are part of other top decreasing profiles in transcriptomic signatures shared by both patients (pre-B cells development – GSE24814 signature, dendritic cells – GSE29949 signature, CD4 differentiation versus CD8 – GSE8835 signature, and IL-10 mediated anti-inflammatory pathway in macrophages – GSE9509 signature) (Figure 2A). Overall, the observed behavior is consistent with an initial early upregulation of immune-related transcripts – likely induced by viral infections – followed by their normalization over time during the course of a few months.
On the other hand, the top five enriched transcriptomic pathways (see Figure 2B) included genes which are part of the B-cell receptor pathway (p-value = 0.0002, see Figure 3) and T-cell receptor pathway (p-value = 0.017, see Supplementary Figure 2), as highlighted by KEGG enrichment analysis. Genes included in such pathways were part of the signatures regulated by IL4 pathway versus Interferon pathway (GSE16385 signature), genes regulating myelo-monocytic differentiation and immunoregulatory activity of tumor-induced myeloid suppressor cells (GSE21927 signature), and interferon induced factors in endothelial cells (GSE3920 signature). Taken together, such findings highlight the progressive development of B- and T-cell mediated immune response towards the likely initial infectious stimulus.