Transient SARS-CoV-2 RNA-Dependent RNA Polymerase Mutations after Remdesivir Treatment for Chronic COVID-19 in Two Transplant Recipients: Case Report and Intra-Host Viral Genomic Investigation

Remdesivir is the first FDA-approved drug for treating severe SARS-CoV-2 infection and targets RNA-dependent RNA polymerase (RdRp) that is required for viral replication. To monitor for the development of mutations that may result in remdesivir resistance during prolonged treatment, we sequenced SARS-CoV-2 specimens collected at different treatment time points in two transplant patients with severe COVID-19. In the first patient, an allogeneic hematopoietic stem cell transplant recipient, a transient RdRp catalytic subunit mutation (nsp12:A449V) was observed that has not previously been associated with remdesivir resistance. As no in vitro study had been conducted to elucidate the phenotypic effect of nsp12:A449V, its clinical significance is unclear. In the second patient, two other transient RdRp mutations were detected: one in the catalytic subunit (nsp12:V166A) and the other in an accessory subunit important for processivity (nsp7:D67N). This is the first case report for a potential link between the nsp12:V166A mutation and remdesivir resistance in vivo, which had only been previously described by in vitro studies. The nsp7:D67N mutation has not previously been associated with remdesivir resistance, and whether it has a phenotypic effect is unknown. Our study revealed SARS-CoV-2 genetic dynamics during remdesivir treatment in transplant recipients that involved mutations in the RdRp complex (nsp7 and nsp12), which may be the result of selective pressure. These results suggest that close monitoring for potential resistance during the course of remdesivir treatment in highly vulnerable patient populations may be beneficial. Development and utilization of diagnostic RdRp genotyping tests may be a future direction for improving the management of chronic COVID-19.

Transplantid.net: A Pilot Crowdsourced, Living, Online Library of Resources for the Teaching and Practice of Transplant Infectious Diseases

The field of transplant infectious diseases is rapidly evolving, presenting a challenge for clinical practice and trainee education. Here we describe the construction of transplantid.net, a free online library, crowdsourced and continuously updated for the dual purpose of point-of-care evidence-based management and teaching.

Delayed mortality among solid organ transplant recipients hospitalized for COVID-19

INTRODUCTION

Most studies of solid organ transplant (SOT) recipients with COVID-19 focus on outcomes within one month of illness onset. Delayed mortality in SOT recipients hospitalized for COVID-19 has not been fully examined.

METHODS

We used data from a multicenter registry to calculate mortality by 90 days following initial SARS-CoV-2 detection in SOT recipients hospitalized for COVID-19 and developed multivariable Cox proportional-hazards models to compare risk factors for death by days 28 and 90.

RESULTS

Vital status at day 90 was available for 936 of 1117 (84%) SOT recipients hospitalized for COVID-19: 190 of 936 (20%) died by 28 days and an additional 56 of 246 deaths (23%) occurred between days 29 and 90. Factors associated with mortality by day 90 included: age > 65 years [aHR 1.8 (1.3-2.4), p =<0.001], lung transplant (vs. non-lung transplant) [aHR 1.5 (1.0-2.3), p=0.05], heart failure [aHR 1.9 (1.2-2.9), p=0.006], chronic lung disease [aHR 2.3 (1.5-3.6), p<0.001] and body mass index ≥ 30 kg/m 2 [aHR 1.5 (1.1-2.0), p=0.02]. These associations were similar for mortality by day 28. Compared to diagnosis during early 2020 (March 1-June 19, 2020), diagnosis during late 2020 (June 20-December 31, 2020) was associated with lower mortality by day 28 [aHR 0.7 (0.5-1.0, p=0.04] but not by day 90 [aHR 0.9 (0.7-1.3), p=0.61].

CONCLUSIONS

In SOT recipients hospitalized for COVID-19, >20% of deaths occurred between 28 and 90 days following SARS-CoV-2 diagnosis. Future investigations should consider extending follow-up duration to 90 days for more complete mortality assessment.

Changing trends in mortality among solid organ transplant recipients hospitalized for COVID-19 during the course of the pandemic

Mortality among patients hospitalized for COVID-19 has declined over the course of the pandemic. Mortality trends specifically in solid organ transplant recipients (SOTR) are unknown. Using data from a multicenter registry of SOTR hospitalized for COVID-19, we compared 28-day mortality between early 2020 (March 1, 2020-June 19, 2020) and late 2020 (June 20, 2020-December 31, 2020). Multivariable logistic regression was used to assess comorbidity-adjusted mortality. Time period of diagnosis was available for 1435/1616 (88.8%) SOTR and 971/1435 (67.7%) were hospitalized: 571/753 (75.8%) in early 2020 and 402/682 (58.9%) in late 2020 (p < .001). Crude 28-day mortality decreased between the early and late periods (112/571 [19.6%] vs. 55/402 [13.7%]) and remained lower in the late period even after adjusting for baseline comorbidities (aOR 0.67, 95% CI 0.46-0.98, p = .016). Between the early and late periods, the use of corticosteroids (≥6 mg dexamethasone/day) and remdesivir increased (62/571 [10.9%] vs. 243/402 [61.5%], p < .001 and 50/571 [8.8%] vs. 213/402 [52.2%], p < .001, respectively), and the use of hydroxychloroquine and IL-6/IL-6 receptor inhibitor decreased (329/571 [60.0%] vs. 4/492 [1.0%], p < .001 and 73/571 [12.8%] vs. 5/402 [1.2%], p < .001, respectively). Mortality among SOTR hospitalized for COVID-19 declined between early and late 2020, consistent with trends reported in the general population. The mechanism(s) underlying improved survival require further study.

Impact of diabetes mellitus on clinical outcomes after heart transplantation

PURPOSE

Diabetes mellitus (DM) is common among recipients of heart transplantation (HTx) but its impact on clinical outcomes is unclear. We evaluated the associations between pretransplant DM and posttransplant DM (PTDM) and outcomes among adults receiving HTx at a single center.

METHODS

We performed a retrospective study (range 01/2008 - 07/2018), n = 244. The primary outcome was survival; secondary outcomes included acute rejection, cardiac allograft vasculopathy, infection requiring hospitalization, macrovascular events, and dialysis initiation post-transplant. Comparisons were performed using Kaplan-Meier and multivariable Cox regression analyses.

RESULTS

Pretransplant DM was present in 75 (30.7%) patients and was associated with a higher risk for infection requiring hospitalization (p<0.05), but not with survival or other outcomes. Among the 144 patients without pretransplant DM surviving to one year, 29 (20.1%) were diagnosed with PTDM at the 1-year follow-up. After multivariable adjustment, PTDM diagnosis at 1-year remained associated with worse subsequent survival (hazard ratio 2.72, 95% confidence interval 1.03-7.16). Predictors of PTDM at 1-year included cytomegalovirus seropositivity and higher prednisone dose (>5mg/day) at 1-year follow-up.

CONCLUSIONS

Compared to HTx recipients without baseline DM, those with baseline DM have a higher risk for infections requiring hospitalization, and those who develop DM after HTx have worse survival. This article is protected by copyright. All rights reserved.

COVID-19 in hospitalized lung and non-lung solid organ transplant recipients: A comparative analysis from a multicenter study

Lung transplant recipients (LTR) with coronavirus disease 2019 (COVID-19) may have higher mortality than non-lung solid organ transplant recipients (SOTR), but direct comparisons are limited. Risk factors for mortality specifically in LTR have not been explored. We performed a multicenter cohort study of adult SOTR with COVID-19 to compare mortality by 28 days between hospitalized LTR and non-lung SOTR. Multivariable logistic regression models were used to assess comorbidity-adjusted mortality among LTR vs. non-lung SOTR and to determine risk factors for death in LTR. Of 1,616 SOTR with COVID-19, 1,081 (66%) were hospitalized including 120/159 (75%) LTR and 961/1457 (66%) non-lung SOTR (p = .02). Mortality was higher among LTR compared to non-lung SOTR (24% vs. 16%, respectively, p = .032), and lung transplant was independently associated with death after adjusting for age and comorbidities (aOR 1.7, 95% CI 1.0-2.6, p = .04). Among LTR, chronic lung allograft dysfunction (aOR 3.3, 95% CI 1.0-11.3, p = .05) was the only independent risk factor for mortality and age >65 years, heart failure and obesity were not independently associated with death. Among SOTR hospitalized for COVID-19, LTR had higher mortality than non-lung SOTR. In LTR, chronic allograft dysfunction was independently associated with mortality.

Vaccine-Associated Measles in a Hematopoietic Cell Transplant Recipient: Case Report and Comprehensive Review of the Literature

Measles is a worldwide viral disease that can cause fatal complications in immunocompromised hosts such as hematopoietic cell transplant (HCT) recipients. The live attenuated measles, mumps, and rubella (MMR) vaccine is generally contraindicated post-HCT due to the risk for vaccine-associated measles. This, combined with decreasing vaccination rates due to vaccine hesitancy and the coronavirus disease 2019 pandemic, raises significant concerns for a measles resurgence that could portend devastating consequences for immunocompromised hosts. Multiple guidelines have included criteria to determine which HCT recipients can safely receive the MMR vaccine. Here, we report a case of vaccine-associated measles in a HCT recipient who met guideline-recommended criteria for MMR vaccination. The objective of this article is to query these criteria, highlight the importance of MMR vaccination, and comprehensively review the literature.

A Multicenter Prospective Registry Study of Lung Transplant Recipients Hospitalized with COVID-19

Purpose

Outcomes of lung transplant recipients (LTR) hospitalized for COVID-19 and comparisons to non-lung solid organ transplant recipients (SOTR) are incompletely described.

Methods

Using a multicenter prospective registry of SOTR, we examined 28-day outcomes (mortality [primary outcome], intensive care unit (ICU) admission, mechanical ventilation, and bacterial pneumonia) among both LTR and non-lung SOTR hospitalized with laboratory-confirmed COVID-19 diagnosed between March 1, 2020 and September 21, 2020. Data were analyzed using Stata (StataCorp, College Station, TX); chi-square tests were used to compare categorical variables and multivariable logistic regression was used to assess risk factors for mortality.

Results

The cohort included 72 LTR and 392 non-lung SOTR (Table 1). Overall, 28-day mortality trended higher in LTR vs. non-lung SOTR (27.8% vs. 19.9%, P=0.136). Other 28-day outcomes were similar between LTR and non-lung SOTR: ICU admission (45.8% vs. 39.1%, P=0.28), mechanical ventilation (32.9% vs. 31.1%, P=0.78), and bacterial pneumonia (15.3% vs. 8.2%, P=0.063). Congestive heart failure, diabetes, age >65 years, and obesity (BMI >= 30) were independently associated with mortality in non-lung SOTR, but not in LTR (Table 2).

Conclusion

In this large prospective cohort comparing lung and non-lung SOTR hospitalized for COVID-19, there were high but not significantly different rates of short-term morbidity and mortality. Baseline comorbidities appeared to drive mortality in non-lung SOTR but not LTR. Further studies are needed to identify risk factors for mortality among LTR.

Herpesvirus Infections Potentiated by Biologics

Herpesviruses such as herpes simplex virus (HSV) type 1 and 2, varicella-zoster virus (VZV), and cytomegalovirus (CMV) maintain lifelong latency in the host after primary infection and can reactivate periodically either as asymptomatic viral shedding or as clinical disease. Immunosuppression, including biologic therapy, may increase frequency and severity of herpesvirus reactivation and infection. Licensed biologics are reviewed regarding their risks of potentiating HSV, VZV, and CMV reactivation and infection. Approaches to prophylaxis against HSV, VZV, and CMV infection or reactivation are discussed.

1109. Valgancyclovir Dosing for Cytomegalovirus Prophylaxis in Heart Transplant Recipients

Background

Cytomegalovirus (CMV) is one of the most common infections after transplantation and continues to cause significant morbidity and mortality. Current guidelines recommend 3-6 months of post-transplant prophylaxis with 900mg daily of valganciclovir in heart transplant recipients. At our institution, however, the protocol is to use 450mg daily of valganciclovir for 6-12 months for intermediate risk (R+) patients and 900 mg daily for high risk (D+/R-) patients. In this study we aimed to identify underlying patient characteristics associated with detectable viral load above the quantifiable threshold.

Table 1. Comparison of patients with a CMV viral above and below 137.

Methods

We retrospectively reviewed medical records of adult (≥ 18 years) heart transplant recipients with detectable CMV viremia from 2016-2018 resulted during routine clinical screening.

Results

Ninety-seven heart transplant recipients with a detectable CMV viral load were identified. Of those, 38 (37.2%) had a quantifiable viral load above the 137 IU/mL threshold. When compared to the individuals with a detectable viral load below the threshold (< 137 IU/mL), they had similar age at time of transplant, increased likelihood of donor/recipient CMV IgG mismatch, and were more frequently on 900mg daily of prophylaxis at time of viremia. Of the individuals with CMV DNAemia above the threshold, the median time to viremia was 271.4 days and the median peak viral load was 701 IU/mL. When limiting analysis to only recipients who were CMV IgG positive, patients with viremia had similar age and more likely to be on 900mg daily of valganciclovir as prophylaxis when compared to individuals with CMV viremia < 137 IU/mL. When comparing CMV D+/R- patients, age and rates of 900mg valganciclovir as prophylaxis were similar (Table 1).

Conclusion

We found that despite receipt of CMV prophylaxis, an appreciable number of both R+ and D-/R+ heart transplant recipients developed breakthrough DNAemia despite being on prophylaxis of valganciclovir as recommended by guidelines. Despite receipt of the higher 900 mg daily dose, high risk patients had higher rates of breakthrough DNAemia at our institution compared with R+ intermediate risk patients. More research is needed to evaluate the optimal dose and duration for prophylaxis in heart transplant patients against CMV.

Disclosures

All Authors: No reported disclosures

Spectrum of Coronavirus Disease 2019 Outcomes in Kidney Transplant Recipients: A Single-Center Experience

PURPOSE

We reviewed the clinical experience of kidney transplant recipients diagnosed with severe acute respiratory syndrome coronavirus 2 infection in order to understand the impact of the current coronavirus disease 2019 (COVID-19) pandemic infection on transplant recipients. Given that early reports from heavily affected areas demonstrated a very high mortality rate amongst kidney transplant recipients, ranging between 30% and 40%, we sought to evaluate outcomes at a center with a high burden of cases but not experiencing acute crisis due to COVID-19.

PROCEDURES

In this single center retrospective observational study, medical records of all kidney transplant recipients at the UCLA Medical Center were reviewed for a diagnosis of COVID-19 by polymerase chain reaction, followed by chart review to determine kidney transplant characteristics and clinical course.

MAIN FINDINGS

A total of 41 kidney transplant recipients were identified with COVID-19 positive polymerase chain reaction. Recipients had been transplanted for a median of 47 months before diagnosis. The large proportion of infected individuals were minorities (Hispanic 65.9%, black 14.6%), on prednisone, tacrolimus, and mycophenolate mofetil (95.1%, 87.8%, and 87.8%, respectively), and had excellent allograft function (median 1.25 mg/dL). The most common presenting symptoms were fever, dyspnea, or cough. Most patients were hospitalized (63.4%); mortality was 9.8% and occurred only in patients in the intensive care unit. The most common treatment was reduction or removal of antimetabolite (77.8%). Approximately 26.9% presented with AKI.

CONCLUSIONS

COVID-19 infection in kidney transplant recipients results in a higher rate of hospitalization and mortality than in the general population. In an area with a high number of infections, the mortality rate was lower compared with earlier reports from areas experiencing early surge and strain on the medical system. Minorities were disproportionately affected. Future studies are needed to determine optimal approach to treatment and management of immunosuppression in kidney transplant recipients with COVID-19 infection.

Diagnosis of Chagasic Encephalitis by Sequencing of 28S rRNA Gene

We report a case of chagasic encephalitis diagnosed by 28S rRNA sequencing. The diagnosis of chagasic encephalitis is challenging, given the broad differential diagnosis for central nervous system lesions in immunocompromised patients and low sensitivity of traditional diagnostics. Sequencing should be part of the diagnostic armamentarium for potential chagasic encephalitis.

Outcomes of patients with infection related to a ventricular assist device after heart transplantation

BACKGROUND

Despite significant advances in durable mechanical support survival, infectious complications remain the most common adverse event after ventricular assist device (VAD) implantation and the leading cause of early death after transplantation. In this study, we aim to describe our local infectious epidemiology and review short-term survival and infectious incidence rates in the post-transplantation period and assess risk factors for infectious episodes after transplantation.

METHODS

Retrospective single-center study of all consecutive adult heart transplant patients from 2008 to 2017. Survival data were estimated and summarized using the Kaplan-Meier method. We quantified and evaluated the difference in the incidence rate between patients with and without infection using a Fine-Gray model. The outcome of interest is the time to first infection diagnosis with post-transplant death as the competing event.

RESULTS

Among 278 heart transplant patients, 74 (26.5%) underwent LVAD implantation. Twenty-one patients (28.3%) developed an infection while supported by an LVAD. When compared to patients supported by an LVAD without a preceding infection, BMI was significantly greater (31.2 vs 27.8 kg/m² , P = .03). Median follow-up post-transplantation was 3.01 years. Significant risk factors for the competing risk regression for infection after heart transplantation include LVAD infection (HR 1.94, [95% CI] 1.11-3.39, P = .020) and recipient COPD (HR 2.14, [95% CI] 1.39-3.32, P = .001) when adjusted for recipient age, gender, hypertension, diabetes mellitus, and body mass index.

CONCLUSIONS

Patients with LVAD-related infection had a significantly increased risk of infectious complications after heart transplantation. Further research on the avoidance of induction agents and reduced maintenance immunosuppression in this patient population is warranted.

Cut it out! Thoracic surgeon's approach to pulmonary mucormycosis and the role of surgical resection in survival

BACKGROUND

Mucormycosis portends a poor prognosis with mortality rates ranging from 50% to 70% in pulmonary mucormycosis (PM) and up to 95% in disseminated disease. However, detailed outcomes data have been lacking. It remains unknown how to identify patients who would benefit from surgical resection.

OBJECTIVES

We present our experience with patients undergoing surgical resection for PM, including an analysis of factors affecting postoperative survival. We also describe a thoracic surgeon's approach through illustrative cases.

PATIENTS/METHODS

We conducted a single-centre retrospective study of all adult patients with PM who received antifungal therapy and underwent surgical resection or who received antifungal therapy alone at Stanford between January 2004 and June 2018.

RESULTS

Twelve patients received antifungal therapy and underwent surgical resection and 13 patients received antifungal therapy alone. From infection onset to death (or right-censoring if still alive), patients who underwent surgical resection had a median survival of 406 days (mean, 561.3; range, 22-2510), and patients who received antifungal therapy alone had a median survival of 28 days (mean, 66.7; range, 8-447). In patients who underwent surgical resection, median postoperative survival time was 154 days (range, 11-2495), in-hospital mortality was 16.7%, and 1-year mortality was 50.0%. Age, primary disease, ASA status, extrapulmonary dissemination, laterality, multilobar involvement, number of lesions, largest lesion size, platelet count, surgical approach, type of resection or extent of resection were not significantly associated with postoperative survival.

CONCLUSIONS

Surgical resection significantly increases survival and should be strongly considered for selected patients with PM.

Prevention of infectious diseases in patients with Good syndrome

PURPOSE OF REVIEW

Good syndrome is a profoundly immunocompromising condition with heterogeneous immune deficits characterized by the presence of thymoma, low-to-absent B-lymphocyte counts, hypogammaglobulinemia, and impaired cell-mediated immunity. Opportunistic infectious diseases associated with Good syndrome represent a diagnostic and therapeutic challenge, given their protean clinical manifestations. Although these infectious complications have been reviewed in prior publications, recommendations regarding their prevention have been lacking.

RECENT FINDINGS

Good syndrome usually occurs in adult patients between the ages of 40 and 70 years. Immunologically, it is characterized by low or absent peripheral blood B lymphocytes, hypogammaglobulinemia, and variable defects in cell-mediated immunity including low CD4 T counts, inverted CD4:CD8 T-lymphocyte ratio, and reduced T-lymphocyte mitogen proliferative responses. Patients with Good syndrome are susceptible to a variety of infectious diseases, of which the most common are recurrent bacterial sinopulmonary infections, mucocutaneous candidiasis, and CMV tissue-invasive disease. Preventive guidelines including targeted antimicrobial prophylaxis and vaccination strategies can mitigate infectious complications in patients with Good syndrome.

SUMMARY

Immunological deficits and infectious complications in Good syndrome have been described for over 60 years. Further research is needed to elucidate its exact pathogenesis and define the mechanistic relationship between thymoma and hypogammaglobulinemia. However, tailored prophylactic strategies can be recommended for patients with Good syndrome.

Successful eradication of chronic symptomatic Candida krusei urinary tract infection with increased dose micafungin in a liver and kidney transplant recipient: Case report and review of the literature

Treatment of symptomatic candiduria is notoriously challenging because of the limited repository of antifungals that achieve adequate urinary concentrations. Fluconazole, amphotericin B-based products, and flucytosine are established treatment options for most Candida species. Candida krusei exhibits intrinsic resistance to fluconazole and decreased susceptibility to amphotericin B and flucytosine. In transplant patients, both amphotericin B-based products and flucytosine are less desirable because of their toxicities. Other triazole antifungals are unappealing because they do not achieve adequate urinary concentrations, have multiple toxicities, and interact with transplant-related immunosuppressive medications. Echinocandins are well-tolerated but have been traditionally deferred in the treatment of symptomatic funguria because of their poor urinary concentrations but there is a small but emerging body of literature supporting their use. Here, we present a case of successful eradication of chronic symptomatic C krusei urinary tract infection with micafungin 150 milligrams daily in a liver and kidney transplant recipient, and we review the literature on treatment of symptomatic candiduria.

Eremothecium coryli bloodstream infection in a patient with acute myeloid leukemia: first case report of human infection

Eremothecium coryli is a dimorphic fungus of the Saccharomycetes class. While species within this class are known to cause human infection, Eremothecium species have previously only been known as phytopathogens and never been isolated from a human sample. Here, we report the first known case of human E. coryli infection.

1573. Discrepancies Between Premortem and Postmortem Diagnoses of Infectious Diseases Found on Autopsy in Hematopoietic Cell Transplantation Recipients at a High-Volume Academic Transplant Center

Background

Methods

Results

Conclusion

Disclosures

Integration of Next–Generation Sequencing, Viral Sequencing, and Host-Response Profiling for the Diagnosis of Acute Infections

Background

To guide treatment of infectious diseases, clinicians need sensitive, specific, and rapid diagnostics. We aim to incorporate complementary methods of microbial sequencing and host-response profiling to improve the diagnosis of patients at risk for acute infections.

Methods

We enrolled 200 adult patients with systemic inflammatory response syndrome (SIRS) at the Stanford Emergency Department. Physicians with specialty training in infectious diseases conducted retrospective two-physician chart review to establish likely admission diagnoses. Blood samples were tested with a previously described 18-gene host-response integrated antibiotics decision model (IADM) that distinguishes noninfectious SIRS, bacterial infections and viral infections. Plasma samples were tested with shotgun metagenomic next-generation sequencing (NGS) and viral sequencing with VirCapSeq. A novel statistical algorithm was developed to identify contaminant organism sequences in NGS data.

Results

The physician chart review classified 99 patients (49%) as infected, 69 (35%) possibly infected and 32 (16%) non-infected. Compared with chart review, the IADM distinguished bacterial from viral infections with an area under curve of 0.85 (95% confidence interval 0.77–0.93). NGS results to date confirmed positive blood cultures in seven of nine patients, with two of four blood culture-positive E. coli patients turning up negative on NGS due to E. coli contamination. NGS also confirmed positive cultures from other sites in two of six patients with negative blood cultures. Preliminary VirCapSeq data from 23 patients confirmed positive viral tests in five of six patients with Hepatitis C, BK Virus, Cytomegalovirus and Epstein–Barr Virus infections. VirCapSeq did not identify a causative agent in the plasma of 11 patients with confirmed respiratory viral infection and intestinal Norovirus infection, and six patients with idiopathic illness. Interestingly, VirCapSeq found viral reactivation in 8 of 12 immunocompromised patients.

Conclusion

The diagnosis of suspected infections may be enhanced by integrating host-response and microbial data alongside clinical judgment. Our results and large cohort lay the foundation to demonstrate the utility of this approach and in which patients these tools may be most useful.

Disclosures

T. E. Sweeney, Inflammatix, Inc: Employee and Shareholder, Salary; T. Briese, Roche: Columbia University has licensed VirCapSeq to Roche, Licensing agreement or royalty; W. I. Lipkin, Roche: Columbia University has licensed VirCapSeq to Roche., Licensing agreement or royalty; P. Khatri, Inflammatix, Inc.: Co-founder, Scientific Advisor and Shareholder, Licensing agreement or royalty and ownership stock; D. A. Relman, Karius: Consultant, Stock options; Arc Bio LLC: Consultant, Stock options

Establishment of an in vitro cell model system to study human prostate carcinogenesis

A positive family history of prostate cancer is a risk factor for this disease, suggesting that alterations of certain genes may play an important role in the development and progression of prostate cancer. However, genetic alterations responsible for initiation and acquisition of metastatic phenotypes by prostate cancer are not well defined. We have observed a consistent change in chromosome 5 in an in vitro cell model of human prostate carcinogenesis in which the near-diploid cells from the surrounding tissue of an adenocarcinoma of the prostate obtained from a 42-year-old patient were subjected to in vitro cell culture and passages. We have examined three different passages of this cell strain by conventional and molecular cytogenetic methods and have seen an increased number of alterations in chromosome 5 in higher passage cells, with accompanying changes in cell morphology. In late passages of this cell line, no cell showed two normal copies of chromosome 5 as analyzed by G-banding and fluorecent in situ hybridization (FISH). The long arm (q) of chromosome 5 was either missing or involved in structural rearrangements. This observation suggests that the q arm of chromosome 5 may carry a tumor suppressor gene(s) that is well-expressed in normal prostate tissue, but when one of these tumor suppressor gene(s) is mutated or deleted and its encoded mRNA and protein are differentially expressed or not expressed at all in the prostate cells, then it may lead to initiation of tumor growth and development. Cytogenetic analyses of early passage cells in this cell strain revealed that approximately 78.8% of metaphases were normal, with a 46,XY chromosome constitution, and 21.2% of cells had clonal alterations mostly of chromosomes 5, 7, 8, 15, 16 and Y. In the middle passages, abnormal cells increased in number (78.26%) and also showed a large number of chromosomal changes. In the late passages, all cells showed structural and numerical abnormalities of the same chromosomes, in addition to some new markers; no cells were found to have a normal karyotype. These chromosomal aberrations could be considered early markers of prostate carcinogenesis. Some of the markers present in late passage cells were similar to those reported in a well-characterized prostate cancer cell line, LNCaP.