Yetmar, Zachary A.

Abstract Background Pneumocystis jirovecii pneumonia (PCP) is a potentially deadly infection afflicting the immunocompromised population, including solid organ transplant recipients. Several risk factors have been described, including acute rejection, lymphopenia, and cytomegalovirus (CMV) infection. However, little is known regarding the risk imparted by posttransplant lymphoproliferative disorder (PTLD). Methods We performed a nested case-control study of solid organ transplant recipients diagnosed with PCP from 2000-2020. PCP was defined as positive smear or polymerase chain reaction testing with compatible clinical symptoms and radiographic findings. Two control were matched to each case by year of first transplant, first transplanted organ, and sex. Each control had at least as much follow-up from their transplant date to their matched case’s PCP diagnosis date. Multivariable conditional logistic regression was performed to analyze theorized risk factors. Results Sixty-seven cases met inclusion criteria and were matched to 134 controls (Table 1). Median age was 60.9 years, and the most common transplant type was kidney (52.2%). Fourteen patients had a history of PTLD, 12 of which developed PCP. All cases of PTLD were monomorphic, 6 were EBV-positive, 9 were receiving chemotherapy at the index date, and only 1 control patient was receiving PCP prophylaxis. The cases with PTLD developed PCP a median of 85 days after PTLD diagnosis, while the two controls were diagnosed more than 1 year earlier. After adjusting for age, acute rejection requiring treatment within the last 6 months, CMV infection within 6 months, current PCP prophylaxis, and lymphopenia (lymphocyte count < 0.5 x109/L) within 6 months, PTLD had a significant association with PCP (OR 14.0, 95% CI 1.7-114.5; p = .014). Lymphopenia was also associated with PCP (OR 8.2, 95% CI 3.2-20.7; p < .001), while the other factors were not. Table 1:Characteristics of 67 Solid Organ Transplant Recipients with Pneumocystis Pneumonia and 134 Matched Controls Conclusion Diagnosis of PTLD is independently associated with subsequent PCP after adjustment for recognized risk factors. This association is likely influenced by PTLD-directed chemotherapy, particularly regimens containing rituximab. PCP prophylaxis should be initiated in solid organ transplant recipients with PTLD, particularly those undergoing active therapy, and those with severe lymphopenia. Disclosures All Authors: No reported disclosures.

Abstract Background Posaconazole therapeutic drug monitoring (TDM) is widely utilized to assess therapeutic efficacy and safety (i.e., hepatotoxicity, QTc prolongation); however, little is known about clinical effects of very high serum posaconazole serum levels (i.e., ≥ 5000 mg/mL). Reported incidence rate of adverse drug reactions (ADRs) with posaconazole per most recent clinical trial was ∼30%. The primary objective was to compare the ADR incidence in patients with serum posaconazole levels of 3000-4999 ng/mL to ≥5000 ng/mL. Methods This retrospective cohort study included adult patients with a posaconazole serum level ≥3000 ng/mL from 1/1/2019 to 04/30/2021. The primary outcome was symptomatic ADR at time of first serum level ≥3000 ng/mL. Secondary outcomes were laboratory defined hepatoxicity, electrolyte and adrenal laboratory abnormalities, QTc changes, and dose changes in response to TDM. Patient outcomes were censored after the first serum level and were compared between groups using Fisher’s exact tests. Results Ninety patients met inclusion criteria, 80 with a level of 3000-4999 ng/mL and 10 with a level of ≥ 5000 ng/mL occurring at a median of 91 days (26-443) and 27 days (12-45) from posaconazole initiation, respectively. Majority of patients were immunocompromised (55.6% transplant recipients, 28.9% active malignancy, 5.6% other) with a split of treatment (50%) and prophylaxis (42.2%) indication. Symptomatic ADRs were very common in patients with posaconazole levels of ≥5000 ng/mL and 3000-4999 ng/mL (80% vs. 58.8%; p=0.31), primarily neurologic (49.1% overall) followed by gastrointestinal (32.7% overall). Hepatotoxicity was also common (≥5000 ng/mL 40% vs 3000-4999 ng/mL 23.4%, p=0.26). Fifty percent of patients had the posaconazole dose continued without change. Electrolytes and QTc results were similar between groups, but median overall QTc was borderline high (456 [IQR 435, 479]). Conclusion There are safety concerns for patients with serum posaconazole levels ≥3000 ng/mL. Posaconazole levels should be monitored and, importantly, dose adjusted according to serum level and patient symptoms for both treatment and prophylaxis indications. Disclosures Christina G. Rivera, PharmD, Gilead: Grant/Research Support|Gilead: Honoraria|Insmed: Honoraria.

Abstract Background Eculizumab, an inhibitor of terminal complement activation, has been utilized in pre-transplant desensitization, treatment of antibody-mediated rejection and thrombotic microangiopathy in solid organ transplant recipients (SOTR). Eculizumab is associated with meningococcal disease, leading to guidelines for vaccination against serogroups ACWY (menACWY) and B (menB) at least 2 weeks prior to eculizumab therapy. In persons requiring emergent use of eculizumab, prophylaxis for at least 2 weeks is recommended. SOTRs respond suboptimally to vaccination, raising consideration for pre-transplant vaccination and prolonged prophylaxis in those undergoing eculizumab therapy. We sought to describe meningococcal vaccination and prophylaxis practices among SOTRs receiving eculizumab. Methods We performed a retrospective chart review of meningococcal vaccination, including number and timing pre- or post-transplant, along with prophylaxis prescribing and duration in SOTRs receiving eculizumab across 3 distinct Mayo Clinic Enterprise sites (Rochester, Arizona, and Florida). Results 200 SOTRs receiving at least one dose of eculizumab between 1/1/2008 and 9/16/2021 were reviewed. Eculizumab indications included antibody mediated rejection (38%), desensitization (26%), and thrombotic microangiopathy (19%). 83% (166/200) of SOTRs received eculizumab for an unanticipated post-transplant complication. Vaccination rates were 82% (164/200) and 35.5% (71/200) for menACWY dose 1 and 2, respectively, and 54% (108/200) and 28.5% (57/200) for menB dose 1 and 2, respectively. The majority received their first vaccination post-transplant: menACWY 66.5% (133/200) and menB 2.5% (185/200). Among those without vaccination pre-eculizumab, 22.3% (41/184) were not prescribed prophylaxis. The median duration of prophylaxis was 62 (range 4-2651) days. Conclusion Most SOTRs underwent meningococcal vaccinations near the time of eculizumab administration post-transplant for an unanticipated complication. One-fifth of those meeting criteria were not provided meningococcal prophylaxis. These findings may support pre-transplant administration of meningococcal vaccinations and heightened awareness for meningococcal prophylaxis in SOTRs receiving eculizumab. Disclosures All Authors: No reported disclosures.

Abstract Background Cytomegalovirus (CMV) causes significant morbidity in solid organ transplant recipients (SOTR). As a lack of immunity predisposes to infection, a laboratory test that measures CMV-specific cell-mediated immunity (CMV CMI) may help guide antiviral prophylaxis, predict relapses and correlate with outcomes. We assessed CMV CMI in CMV D+/R- patients during valganciclovir primary prophylaxis and in CMV viremic SOTRs during antiviral treatment, and correlated the results with post-prophylaxis CMV infection and post-treatment relapse, respectively. Methods CMV CMI was assessed in two groups of SOTRs using the QuantiFERON© CMV interferon-gamma release assay (IGRA), with level >0.2 IU/mL suggestive of immunity. The first group included CMV D+/R- SOTRs who underwent monthly CMV CMI testing during 6 months of valganciclovir prophylaxis. These patients were prospectively followed for CMV episodes for 1 year post transplant. The second group included SOTRs with CMV viremia or disease, who underwent CMV CMI testing at time of CMV diagnosis and at various time points during antiviral treatment. These patients were prospectively followed for CMV relapse for 1 year post-primary CMV episode. Standard definitions were used to define CMV infection and disease. Results In the primary prophylaxis cohort, 24 CMV mismatched (D+/R-) SOTRs were enrolled. Only 1 patient (4.2%) demonstrated a CMV CMI >0.2 IU/mL by the end of prophylaxis; this patient did not develop CMV disease. Four (16.6%) patients developed post-prophylaxis CMV infection, none of which had CMV CMI >0.2 IU/ml. In the post-treatment cohort, 20 CMV viremic SOTRs were enrolled, including 12 D+/R- (60%). Eighteen (90%) had CMV CMI levels >0.2 IU/mL by end of treatment and none developed CMV relapse. In contrast, the single patient who relapsed after treatment had a CMV CMI response < 0.2 IU/ml (p=0.05). Conclusion CMV D+/R- SOTRs are unlikely to develop CMV CMI during valganciclovir prophylaxis. Thus, the utility of CMV CMI for risk stratification of post-prophylaxis CMV infection in CMV D+/R- SOTRs is questionable. Conversely, CMV CMI testing may potentially be a useful marker of CMV relapse risk after treatment and guide the role of secondary antiviral prophylaxis. Disclosures Elitza Theel, PhD, D(ABMM), Euroimmun US: Advisor/Consultant|Oxford Immunotech: Advisor/Consultant|Roche Diagnostics: Advisor/Consultant|Serimmune Inc: Advisor/Consultant Raymund R. Razonable, MD, American Society of Transplantation: Board Member|gilead: Grant/Research Support|novartis: DSMB|regeneron: Grant/Research Support|Roche: Grant/Research Support.

Abstract Background Methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia requires weeks of IV antimicrobial therapy for treatment with antistaphylococcal penicillins (ASP) and first-generation cephalosporins being mainstays of therapy. While effective, use of these agents in the outpatient setting requires frequent dosing along with close toxicity monitoring through the duration of therapy. Ceftriaxone is an appealing alternative given daily dosing and tolerability, but efficacy in this setting remains uncertain. We sought to review outcomes of patients who received ceftriaxone versus an ASP and first-generation cephalosporins for definitive therapy of MSSA bacteremia. Methods Following IRB approval, we reviewed medical records of a retrospective adult cohort diagnosed with MSSA bacteremia treated with ceftriaxone, cefazolin, or an ASP between January 2018 and December 2019 at Mayo Clinic campuses. Treatment was defined as the antibiotic used in the outpatient setting. The primary outcome was 90-day treatment failure, defined as a composite of mortality and microbiologic relapse. Secondary outcomes were 30-day treatment failure and individual components of treatment failure. Multivariable Cox regression analysis was performed to analyze for an association between ceftriaxone use and the primary outcome after adjusting for factors that may also impact outcomes. Kaplan-Meier curves were compared utilizing a log-rank test for survival between groups. Results A total of 223 patients with the accompanying characteristics met study criteria (Table 1). Thirty-seven received ceftriaxone (16.5%) and 186 (83.4%) were treated with cefazolin or an ASP. Ninety and 30-day treatment failure were higher in those treated with ceftriaxone (27%, 8.1%) compared to cefazolin or an ASP (8.6%, 3.8%). Multivariable analysis for risk of 90-day treatment failure revealed a hazard ratio of 2.91 for ceftriaxone (Table 2) and a significant difference in event-free survival for those treated with ceftriaxone compared to cefazolin or an ASP (Figure 1). Conclusion Patients receiving definitive therapy with ceftriaxone for MSSA bacteremia experienced a higher rate of 90 and 30-day treatment failure and a lower rate of event-free survival as compared to those treated with cefazolin or an ASP. Disclosures All Authors: No reported disclosures.

Purpose of review Coronavirus disease-2019 (COVID-19) disproportionately causes severe outcomes in solid organ transplant recipients (SOTR). Antispike monoclonal antibodies have been authorized for therapy and prophylaxis for COVID-19. Here, we review the current state of antispike monoclonal antibodies and their role for SOTRs. Recent findings Bamlanivimab with or without etesevimab, casirivimab-imdevimab and sotrovimab have reduced the rates of hospitalization and severe disease in high-risk patients with mild-to-moderate COVID-19. Multiple retrospective studies have also demonstrated monoclonal antibodies are effective in SOTR populations. However, the evolution of resistant severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concerns has resulted in revocation of the authorization of bamlanivimab with or without etesevimab, and casirivimab-imdevimab as treatment and postexposure prophylaxis (PEP). Sotrovimab and bebtelovimab are currently authorized for treatment of the predominant circulating SARS-CoV-2 B.1.1.529 (Omicron), but not as pre or PEP. Tixagevimab–cilgavimab, a long-acting antibody combination preparation, is authorized for preexposure prophylaxis in high-risk immunocompromised populations, including SOTRs, who are less likely to mount an effective immune response following vaccination series and booster. Summary Antispike monoclonal antibodies are useful for the prevention and treatment of mild-to-moderate COVID-19 in SOTRs. However, their clinical use should be determined by the evolving epidemiology of SARS-CoV-2 variants in the community.

Combination anti-retroviral therapy has drastically improved solid organ transplantation outcomes in persons living with HIV. DAA therapy has led to the successful eradication of HCV. While recent data have suggested improvement in outcomes in HIV/HCV-coinfected liver transplant recipients, temporal trends in patient survival within pre- and post-DAA eras are yet to be elucidated. The UNOS database was utilized to identify deceased donor liver transplant recipients between 1 January 2000 and 30 September 2020 and stratify them by HIV and HCV infection status. A total of 85,730 patients met the inclusion criteria. One-year and five-year patient survival improved (93% and 80%, respectively) for all transplants performed post-2015. For HIV/HCV-coinfected recipients, survival improved significantly from 78% (pre-2015) to 92% (post-2015). Multivariate regression analyses identified advanced recipient age, Black race, diabetes mellitus and decompensated cirrhosis as risk factors associated with higher one-year mortality. Liver transplant outcomes in HIV/HCV-coinfected liver transplant recipients have significantly improved over the last quinquennium in the setting of the highly effective combination of ART and DAA therapy. The presence of HIV, HCV, HIV/HCV-coinfection and active HCV viremia at the time of transplant do not cause higher mortality risk in liver transplant recipients in the current era.

Background. Nocardia is an environmental pathogen with a predilection for causing opportunistic infections in immunocompromised patients, including solid organ transplant (SOT) recipients. Although risk factors have been identified for developing nocardiosis in this population, little is known regarding clinical factors resulting in poor outcomes. We evaluated a cohort of SOT recipients with nocardiosis for associations with 12-month mortality. Methods. We performed a multicenter retrospective cohort study of adult SOT recipients diagnosed with culture-confirmed nocardiosis from 2000 to 2020. Patients were followed for 12 months after diagnosis, unless abbreviated by mortality. Multivariable Cox regression was performed to analyze associations with 12-month mortality. A subgroup analysis of patients with disseminated nocardiosis was performed to analyze treatment variables. Results. A total of 125 SOT recipients met inclusion criteria; 12-month mortality was 16.8%. Liver transplantation (hazard ratio [HR] 3.52; 95% confidence interval [CI] 1.27-9.76) and time from symptom onset to presentation (HR 0.92/d; 95% CI 0.86-0.99) were independently associated with 12-month mortality, whereas disseminated infection was not (HR 1.23; 95% CI 0.49-3.13). No treatment-specific factors were significantly associated with mortality in 33 patients with disseminated nocardiosis, although survivors had a higher rate of linezolid use. Conclusions. This study identified 2 independent associations with 12-month mortality, representing demographics and infection severity. Disseminated infection was not independently associated with poor outcomes, and specific sites of infection may be more important than dissemination itself. No treatment-specific factors were associated with mortality, though this analysis was likely underpowered. Further study of treatment strategies based on specific Nocardia syndromes is warranted.