Evaluation of Three Cytomegalovirus IgG Lateral Flow Assays for Rapid Determination of CMV Serostatus

Background

Cytomegalovirus (CMV) serostatus is a major determinant of CMV infection, disease risk, and transplant outcomes. Current clinical serology assays are limited by relatively slow turnaround time, design for batched testing, need for trained personnel, and/or specialized equipment. Rapid diagnostic assays in development have a role in emerging settings, such as critically ill patients, but have not been systematically evaluated.

Methods

We assessed the performance of 3 rapid lateral flow assays (LFAs) for the detection of CMV immunoglobulin (Ig)G antibodies compared with a reference commercially available CMV IgG enzyme-linked immunosorbent assay in residual serum samples from 200 consecutive adults who underwent clinical CMV serology testing. Samples with discrepant results between the LFA and reference assay were tested by a second reference assay. A subset of serum samples was assessed for interoperator variability. Operating characteristics of the QooLabs LFA were separately assessed in plasma samples.

Results

The sensitivity and specificity of the individual LFA assays using serum varied significantly: 86%/83%, 99/93%, and 57/97%, for Healgen, QNow automated reader, and nanoComposix, respectively, compared with the reference assay. Results for the QNow assay were comparable between automated and manual reads. Among a subset of 10 serum samples assessed by 5 individual operators, 44 of 50 (88%) results were concordant. Among 50 plasma samples assessed by the QooLabs LFA, the sensitivity and specificity were 72% and 96%.

Conclusions

The ease of performance, rapid turnaround time, and good operating characteristics provide the rationale for further evaluation of the Qoolabs QNow LFA in specialized settings where rapid assessment of CMV serostatus would be advantageous.

Cytomegalovirus breakthrough and resistance during letermovir prophylaxis

Letermovir is a relatively new antiviral for prophylaxis against cytomegalovirus (CMV) after allogeneic hematopoietic cell transplantation (HCT). CMV-seropositive HCT recipients who received letermovir prophylaxis from 2018 to 2020 at our center were evaluated for letermovir resistance and breakthrough CMV reactivation. Two-hundred twenty-six letermovir recipients were identified and 7/15 (47%) with CMV DNAemia ≥200 IU/mL were successfully genotyped for UL56 resistance. A single C325Y resistance mutation was identified in an umbilical cord blood recipient. Ninety-five (42%), 43 (19%), and 15 (7%) patients had breakthrough CMV at any level, ≥150 IU/mL, and ≥500 IU/mL, respectively. Risk factors for breakthrough CMV reactivation at each viral threshold were examined. Cumulative steroid exposure was the strongest risk factor for CMV at all evaluated viral thresholds. Graft-versus-host disease prophylaxis with post-transplantation cyclophosphamide (aHR 2.34, 95% CI 1.28-4.28, p = 0.001) or calcineurin inhibitors plus mycophenolate (aHR 2.24, 95% CI 1.30-3.86, p = 0.004) were also associated with an increased risk of CMV reactivation at any level. De novo letermovir resistance is rare and can be successfully treated using other antivirals. Letermovir effectively prevents clinically significant CMV, however, subclinical CMV reactivation occurs frequently at our center.

491. Characterizing the Association of Pre-Existing Cytomegalovirus (CMV)-specific Humoral Immunity with CMV Reactivation Risk after Hematopoietic Cell Transplantation (HCT)

Background

There is renewed interest in CMV-specific humoral immune protection due to recent murine data suggesting that strain-specific antibodies may inhibit CMV cell-to-cell spread (Science. 2019; 363:288). To characterize the nature of antibody protection against CMV after HCT, we tested pre-HCT sera in a cohort of CMV D-R+ allogeneic HCT recipients from the pre-letermovir era using VirScan, a technology that measures pathogen-specific humoral immunity (IgG) at the epitope level.

Methods

Patients (age 0-70 years) who received 1^st, myeloablative, HCT for acute leukemia or myelodysplastic syndrome and who underwent PCR surveillance and preemptive therapy were included. VirScan was used on sera collected pre-HCT. Cumulative incidence curves and multivariable Cox regression analyses were used to determine the association of pre-HCT CMV antibody epitopes scores with CMV reactivation (any, >150 IU/mL, >500 IU/mL) in the first 8 weeks post-HCT.

Results

170 CMV D-R+ HCT recipients were tested a median of 26 days (range 7-37 days) prior to HCT and had a median of 37 CMV antibody epitopes (IQR 29-50 epitopes, range 14-77 epitopes). The cumulative incidence of CMV reactivation was higher in patients with greater pre-HCT CMV antibody epitopes at each evaluated PCR threshold (Figure 1) and the effect appeared more pronounced in adults (Figure 2). High (≥ 4^th quartile vs. 1^st quartile), pre-HCT CMV antibody epitopes were associated with an increased risk of any CMV reactivation (adjusted Hazard Ratio [aHR]=4.1, 95% confidence interval [CI] 2.1-7.7, p< 0.001) and at >150 IU/mL (aHR=3.0, 95% CI 1.4-6.5 p=0.006) after adjusting for age, HLA-matching, and pre-HCT T-cell depletion ( >150 IU/mL only). Figure 1Figure 2

Conclusion

We observed a paradoxically increased risk of CMV reactivation in patients with high pre-HCT CMV VirScan scores. It is possible that pre-HCT CMV-specific humoral immunity as measured by VirScan is reflective of the burden of latent CMV or that CMV-specific antibodies may mediate antibody-dependent enhancement after HCT and thus facilitate reactivation. Future studies are needed to validate our findings in diverse cohorts and to elucidate the underlying mechanism of increased VirScan scores and associated risks of CMV reactivation.

Disclosures

Rachel A. Bender Ignacio, MD, MPH, Abbvie: Advisor/Consultant|SeaGen: Advisor/Consultant Joshua A. Hill, MD, Allovir: Advisor/Consultant|Allovir: Grant/Research Support|Covance/CSL: Advisor/Consultant|CRISPR: Advisor/Consultant|Deverra: Grant/Research Support|Gilead: Grant/Research Support|Karius: Advisor/Consultant|Karius: Grant/Research Support|Merck: Grant/Research Support|Octapharma: Advisor/Consultant|OptumHealth: Advisor/Consultant|Oxford Immunotec: Grant/Research Support|Pfizer: Advisor/Consultant|Symbio: Advisor/Consultant|Takeda: Advisor/Consultant Geoffrey Hill, M.D., FRACP, FRCPA, Applied Molecular Transport: Grant/Research Support|Compass Therapeutics: Grant/Research Support|Generon Corporation: Advisor/Consultant|Heat Biologics: Grant/Research Support|iTeos Therapeutics: Advisor/Consultant|iTeos Therapeutics: Grant/Research Support|Laevoroc Oncology: Grant/Research Support|NapaJen Pharma: Advisor/Consultant|Neoleukin Therapeutics: Advisor/Consultant|Serplus Technology: Grant/Research Support|Syndax Pharmaceuticals: Grant/Research Support Michael J. Boeckh, MD PhD, Allovir: Advisor/Consultant|Amazon: Grant/Research Support|Ansun Biopharma: Grant/Research Support|EvrysBio: Advisor/Consultant|Gates Ventures: Grant/Research Support|Gilead Sciences: Advisor/Consultant|Gilead Sciences: Grant/Research Support|GlaxoSmithKline: Advisor/Consultant|GlaxoSmithKline: Grant/Research Support|Helocyte: Advisor/Consultant|Janssen: Advisor/Consultant|Janssen: Grant/Research Support|Kyorin Pharmaceuticals: Advisor/Consultant|Merck: Advisor/Consultant|Merck: Grant/Research Support|Moderna: Advisor/Consultant|Moderna: Grant/Research Support|Regeneron: Grant/Research Support|ReViral: Advisor/Consultant|Symbio: Advisor/Consultant|Takeda: Grant/Research Support|Vir Biotechnology: Advisor/Consultant|Vir Biotechnology: Grant/Research Support.

Antibodies against vaccine-preventable infections after CAR-T cell therapy for B cell malignancies

BACKGROUND

Little is known about pathogen-specific humoral immunity after chimeric antigen receptor–modified T (CAR-T) cell therapy for B cell malignancies.

METHODS

We conducted a prospective cross-sectional study of CD19-targeted or B cell maturation antigen–targeted (BCMA-targeted) CAR-T cell therapy recipients at least 6 months posttreatment and in remission. We measured pathogen-specific IgG against 12 vaccine-preventable infections and the number of viral and bacterial epitopes to which IgG was detected (“epitope hits”) using a serological profiling assay. The primary outcome was the proportion of participants with IgG levels above a threshold correlated with seroprotection for vaccine-preventable infections.

RESULTS

We enrolled 65 children and adults a median of 20 months after CD19- (n = 54) or BCMA- (n = 11) CAR-T cell therapy. Among 30 adults without IgG replacement therapy (IGRT) in the prior 16 weeks, 27 (90%) had hypogammaglobulinemia. These individuals had seroprotection to a median of 67% (IQR, 59%–73%) of tested infections. Proportions of participants with seroprotection per pathogen were comparable to population-based studies, but most individuals lacked seroprotection to specific pathogens. Compared with CD19-CAR-T cell recipients, BCMA-CAR-T cell recipients were half as likely to have seroprotection (prevalence ratio, 0.47; 95% CI, 0.18–1.25) and had fewer pathogen-specific epitope hits (mean difference, –90 epitope hits; 95% CI, –157 to –22).

CONCLUSION

Seroprotection for vaccine-preventable infections in adult CD19-CAR-T cell recipients was comparable to the general population. BCMA-CAR-T cell recipients had fewer pathogen-specific antibodies. Deficits in both groups support the need for vaccine and immunoglobulin replacement therapy studies.

FUNDING

Swiss National Science Foundation (Early Postdoc Mobility grant P2BSP3_188162), NIH/National Cancer Institute (NIH/NCI) (U01CA247548 and P01CA018029), NIH/NCI Cancer Center Support Grants (P30CA0087-48 and P30CA015704-44), American Society for Transplantation and Cellular Therapy, and Juno Therapeutics/BMS.

In this prospective study, we investigated antibodies against vaccine-preventable infections and other pathogen-specific antibodies in individuals with remission after CAR-T cell therapy for B lineage malignancies.

Cytomegalovirus Humoral Response Against Epithelial Cell Entry-Mediated Infection in the Primary Infection Setting After Hematopoietic Cell Transplantation

BACKGROUND

The influence of humoral immunity on the prevention of primary cytomegalovirus (CMV) infection after hematopoietic cell transplantation (HCT) is poorly understood.

METHODS

To determine whether neutralizing antibodies (nAbs) against CMV pentameric complex (PC)-mediated epithelial cell entry decrease CMV infection after HCT, samples were analyzed from a randomized controlled trial of CMV intravenous immunoglobulin (IVIG) prophylaxis. Weekly serum from 61 CMV donor-positive/recipient-negative (D+/R-) HCT patients (33 control, 28 CMV IVIG) was tested using a PC-entry nAb assay and quantitative CMV polymerase chain reaction (PCR).

RESULTS

There was a trend toward higher weekly PC-entry nAb titers (P = .07) and decreased CMV infection by PCR at viral load cutoffs of ≥1000 and ≥10 000 IU/mL in the CMV IVIG arm. High nAb titers were not significantly protective against CMV infection later after HCT in both study arms. Among CMV-infected patients, each log2 increase in nAb titer was associated with an average 0.2 log10 decrease in concurrent CMV viral load after infection (P = .001; adjusted for study arm).

CONCLUSIONS

This study provides initial support that CMV IVIG prophylaxis moderately enhances PC-entry nAB activity in D+/R- HCT recipients.