Reynolds, Gina

Background While SARS-CoV-2 vaccines are highly effective in healthy individuals, the magnitude and durability of humoral and cellular responses in patients with solid malignancies receiving chemotherapy remain understudied. Previous reports suggest that patients with cancer may not mount adequate immune response after SARS-CoV-2 vaccination. Additionally, most studies focused on humoral responses, while data regarding cellular immune responses are scarce. In this study, we evaluated humoral and cellular responses in patients with solid tumors receiving chemotherapy compared to healthy individuals up to one year after vaccinations. Methods Patients aged ≥18 who were willing to receive the SARS-CoV-2 vaccine were enrolled. Anti-SARS-CoV-2 immunoassays were used to detect antibodies against nucleocapsid and spike proteins. Human IFN-γ Fluorospot assay was used to determine antigen−specific T-cell responses. Data were compared between groups using Mann−Whitney test for continuous variables and Fisher’s exact test for categorical variables. Results A total of 67 subjects (47 patients with cancer and 20 healthy individuals) were included. 1–3 months following the second vaccine doses, 96% of patients with cancer and 100% of healthy individuals demonstrated a positive humoral response. While the positivity rate was not significantly different, patients with cancer had significantly lower spike IgG antibodies than healthy individuals. However, this difference diminished at 6 months when patients with cancer had increased antibodies compared to decreased antibodies in the healthy cohort and no difference was noticed at 12-month. Patients with cancer developed a similar antigen-specific T-cell response as healthy individuals at 1–3 months, 6 months and 12 months. There were no significant differences when comparing patients aged ≤ 55 years vs. >55 years, stages I-III vs. IV, single vs. multiple chemotherapy, and BNT162b2 vs. mRNA-1273 vaccines. There was a significant moderate correlation between neutralization and antibody levels at 12 months. However, despite patients with cancer having a significantly higher COVID risk score, there were no significant differences in COVID-19 infection and hospitalization between patients with cancer and healthy individuals. Conclusion Despite initial impaired antibody responses to SARS-CoV-2 vaccinations, patients with solid malignancies receiving chemotherapy effectively generated long-term cellular and humoral responses by 6 and 12 months, leading to similar infection and hospitalization rates compared to healthy individuals.

Abstract Background: SARS-CoV-2 mRNA vaccines have been demonstrated to have robust and durable humoral immune response in healthy individuals. However, their effectiveness in immunocompromised patients, particularly cancer patients, remains less known. Newer data suggests that cancer patients may not mount adequate protective immune response after vaccination. Methods: A retrospective study of patients ≥ 18 years old who had SARS-CoV-2 spike antibody (anti-S Ab) testing after 2 doses of SARS-CoV-2 mRNA vaccines between 12-90 days at Mayo Clinic between January 1, 2021 and May 10, 2021 was performed. The Elecsys Anti-SARS-CoV-2 S electrochemiluminescence immunoassay (Roche Diagnostics, Switzerland) was used to measure the antibody response. Patients with prior COVID-19 infection and patients on immunosuppressive therapy for an indication other than cancer were excluded. Categorical variables were summarized as frequencies (percentages) and continuous variables were reported as median with range. Wilcoxon signed rank test was used to compare continuous variables between groups and Chi-squared or Fisher’s exact test was used to compare categorical variables. All tests were two-sided with p value < 0.05 considered statistically significant. The analysis was done using R program version 3.6.2. Results: Among 201 patients, 79 had breast cancer, 91 had a hematologic malignancy, 6 had other solid malignancies, and 25 had no history of cancer. All breast cancer patients on endocrine therapy or trastuzumab ± pertuzumab without chemotherapy (n=35) had anti-S Ab titer ≥ 500 U/mL. Patients on cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) appeared to have low level of anti-S Ab with 28.6% (n=4/14) had anti-S Ab titer ≤ 500 U/mL. Patients on chemotherapy also had low levels of anti-S Ab with 47% (n=14/30) having anti-S Ab titers ≤ 500 U/mL. When combining breast cancer patients on endocrine therapy alone or anti-HER2 therapy with patients without history of cancer as an immunocompetent group, there was significantly greater proportion of immunocompetent patients (97%) who had anti-S Ab titer ≥ 500 U/mL compared with only 8% of patients with hematologic malignancy and 55% of patients with solid malignancy on chemotherapy or CDK4/6i (p < 0.001). Using multivariate logistic regression analysis adjusted for age, gender, and vaccine type, patients with solid malignancies and treatment-related cytopenia, including chemotherapy and CDK4/6i, (OR 35.51 [95%CI 8.38-255.25, p < 0.001]) were more likely than immunocompetent patients to have a suboptimal anti-S Ab results ≤ 500 U/mL.Conclusion: A significant number of breast cancer patients on chemotherapies and CDK4/6i had poor humoral responses after SARS-CoV-2 mRNA vaccination. While CDK4/6i is not commonly considered as immunosuppressive therapy, breast cancer patients on CDK4/6i appeared to have suboptimal response to SARS-CoV-2 mRNA vaccine. Our study also highlights the significance of assessing antibody response after COVID-19 vaccines in these vulnerable patients. Citation Format: Saranya Chumsri, Pooja P. Advani, Tanmayi S Pai, Zhou Li, Marites Acampora, Gina A Reynolds, Alvaro Moreno-Aspitia, Christopher P Marquez, Keith L. Knutson. Antibody responses after SARS-CoV-2 mRNA vaccination in breast cancer patients [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-23-01.

Increasing data support the importance of preexisting host immune response and neoantigen burden for determining response to immune checkpoint inhibitors (ICIs). In lung cancer and melanoma, tumor mutational burden (TMB) has emerged as an independent biomarker for ICI response. However, the significance of TMB in breast cancer, particularly in the context of PD-L1 negativity, remains unclear. This report describes a patient with HER2-negative breast cancer with high TMB and an apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like (APOBEC) trinucleotide signature; her disease was refractory to multiple lines of treatments but achieved durable complete response using ICIs and capecitabine. Additional analysis of the tumor revealed a low amount of stromal tumor-infiltrating lymphocytes (sTILs) and PD-L1 negativity, reflecting a poor preexisting host immune response. In collaboration with Foundation Medicine, comprehensive genomic profiling from 14,867 patients with breast cancer with the FoundationOne test was evaluated. Using the cutoff of ≥10 mutations/megabase (mut/Mb) for high TMB, PD-L1 positivity and TMB-high populations were not significantly overlapping (odds ratio, 1.02;P=.87). Up to 79% of TMB-high tumors with >20 mut/Mb were PD-L1–negative. Our study highlights that despite having low TILs and PD-L1 negativity, some patients may still experience response to ICIs.

289 Background: Cholangiocarcinoma (CC), hepatocellular carcinoma (HCC), and pancreatic ductal adenocarcinoma (PDAC) are all devastating malignancies. Limited data exists about PD-1 and PDL1 expression in these cancers. We assessed expression of PD1/PDL1 in a large cohort of patients with hepato-pancreatico-biliary (HPB) cancers and explored the existence of accompanying genomic mutations associated with expression of PD-1/PD-L1. Methods: 524 patients with HPB cancers (354 PDAC, 58 HCC, 54 intrahepatic (ICC), 18 extrahepatic (ECC), and 40 gallbladder (GBC)) were included in the study and tumors tested centrally at a CLIA lab (Caris Life Sciences, Phoenix, AZ). Tests included one or more of the following: gene sequencing (next generation sequencing, Illumina TruSeq), protein expression (immunohistochemistry [IHC]) and gene amplification). PD-1 (SP142 antibody) and PD-L1 (MRQ-22 antibody) status was tested in all samples. Two-tailed Fisher's exact test was performed to test where proportions of positive results were different by subgroup (p²0.05). Results: Among those with PDAC, HCC, ICC, ECC, and GBC, rates of PD1 expression on tumor infiltrating lymphocytes (TILs) and PD-L1 expression on tumor cells is detailed in the Table. In PD-1+, compared with PD-1- HPB cancers, mutations in the following were more prevalent, though not statistically significant: BRCA2, ATM, CTNNB1, and PIK3CA. Among all theranostic biomarkers tested, TOP2A expression (IHC) was significantly increased in PD-L1+ versus PD-L1- tumors (82% vs 60%; p=0.0083). Conclusions: HPB tumors express PD-L1 at a frequency of 4-18%, and PD-1 at a frequency of 29-45%. A statistically significant association of mutations with PD-1+ or PD-L1+ tumors was not identified in this group of tumors. PD-L1 expression associates with TOP2a expression, a marker of proliferation and also anthracycline sensitivity. Further evaluation of this correlation and PDL1/PD-1 + anthracycline combination therapy may be warranted. [Table: see text]