Leukopenia due to parvovirus B19 in a Crohn's disease patient using azathioprine

Limited added value of laboratory monitoring in thiopurine maintenance monotherapy in inflammatory bowel disease patients

BACKGROUND

To timely detect myelotoxicity and hepatotoxicity, laboratory monitoring at 3-month intervals is advised throughout thiopurine maintenance treatment for IBD. However, reported incidence rates of myelotoxicity and hepatotoxicity in maintenance treatment are low.

AIM

To assess incidence rates and clinical consequences of myelotoxicity and hepatotoxicity in thiopurine maintenance therapy after at least 1 year of thiopurine treatment.

METHODS

Retrospective analysis of therapy adjustment for laboratory toxicity in adult IBD patients after 12 consecutive months of azathioprine (AZA) or mercaptopurine monotherapy (ie baseline) between 2000 and 2016. Incidence rates of laboratory toxicity (ie myelotoxicity [leucocyte count <4.0 × 10e9/L, and/or platelet count <150 × 10e9/L] and/or hepatotoxicity (gamma-glutamyltransferase [GGT], alkaline phosphatase [AP], ALT and/or AST above ULN, excluding isolated increased AST/AP]) and associated diagnostic procedures and complications were assessed.

RESULTS

In total, 12,391 laboratory assessments were performed on 1132 patients (56% female, AZA 74%) during 3.3 years of median follow-up. Median monitoring frequency was 3.1 assessments/treatment year. Only 83/12,391 (0.7%) assessments resulted in therapy adjustment, dose reduction in 46 patients, cessation in 28 and allopurinol initiation in nine; risk of therapy adjustment was 1.9% per treatment year. Incidence rates of myelotoxicity were 7.1% (5.1% mild/1.8% moderate/0.1% severe) and hepatotoxicity 5.1% (3.8% mild/1.1% moderate/0.2% severe) per treatment year. Treatment-related complications with concurrent laboratory toxicity occurred in 12 patients (1.1%) and would not have been prevented by monitoring.

CONCLUSION

Severe laboratory toxicity is uncommon after 1 year of thiopurine monotherapy at 4-month monitoring intervals. Therapy adjustments are rare after detection of laboratory toxicity. After 1 year of thiopurine monotherapy, laboratory monitoring may be lowered to less than a 4-month interval.

Parvovirus B19 infection presenting with neutropenia and thrombocytopenia: Three case reports

RATIONALE

Parvovirus B19 (PV) infection is usually symptomless and can cause benign, short-lived conditions. Anemia associated with PRCA is the most representative hematologic manifestation, but neutropenia and thrombocytopenia have been rarely reported.

PATIENT CONCERNS

Three patients were admitted to the hospital with neutropenia and thrombocytopenia. The accompanying symptoms were fever, myalgia, rash, or arthralgia, and all patients were previously healthy.

DIAGNOSIS

Patients were positive for PV PCR and diagnosed with PV infection. Before the diagnosis of PV infection, 2 patients underwent BM study and almost absence of erythroid progenitor cells in BM aspiration were a clue for the PV infection. Other BM findings were hypocellular marrow and a few hemophagocytic histiocytes.

INTERVENTIONS

Patients received supportive care with follow-up of CBC.

OUTCOMES

All 3 patients spontaneously recovered from neutropenia and thrombocytopenia within 3 weeks without severe complications.

LESSONS

The evaluation of PV infection should be considered in situations where there is neutropenia and thrombocytopenia in healthy individuals even without anemia as a differential diagnosis.

Frequency of human Parvovirus B19 among patients with respiratory infection in Iran

Background: Human parvovirus B19 was known as one of the possible cause of mild respiratory tract diseases in previous studies. However, there are some reports of acute obstructive respiratory disease and severe pneumonia. The purpose of current study was to assess the prevalence and clinical features of parvovirus B19 in respiratory infection. Methods: This study was conducted on 156 patients diagnosed with respiratory infection at the Iran University of Medical Sciencesaffiliated hospitals. After extraction of viral DNA from swab samples, detection of parvovirus B19 was performed by real-time PCR assay. Results: In 156 patient's samples, parvovirus B19 was found in 8 (5.1 %) cases including 5 males (5.9%) and 3 females (4.1%). The most common clinical symptoms were wheezing (100%), tachypnea (100%), fever (75%) and rhinorrhea/pharyngitis (75%). Conclusion: This is the first attempt to assess the prevalence of parvovirus B19 infection in Iranian patients with respiratory infection. The low frequency of parvovirus B19 detected in our study does not support the role of this virus in the development of respiratory infection. However, further studies are needed to better evaluate the etiological role of parvovirus B19 in respiratory infection.

Thiopurines in Inflammatory Bowel Disease: New Findings and Perspectives

Thiopurines, available as azathioprine, mercaptopurine, and thioguanine, are immunomodulating agents primarily used to maintain corticosteroid-free remission in patients with inflammatory bowel disease. To provide a state-of-the-art overview of thiopurine treatment in inflammatory bowel disease, this clinical review critically summarises the available literature, as assessed by several experts in the field of thiopurine treatment and research in inflammatory bowel disease.

Risk factors for thiopurine-induced myelosuppression and infections in inflammatory bowel disease patients with a normal TPMT genotype

BACKGROUND

Leucopenia is a common side effect in patients treated with thiopurines. Variants in the thiopurine S-methyltransferase (TPMT) gene are the best-known risk factor, but only explain up to 25% of leucopenia cases.

AIM

To identify the clinical risk factors for thiopurine-induced leucopenia in patients without a common TPMT variant, and explore if these patients are at increased risk for infections.

METHODS

Post hoc analysis of the Thiopurine response Optimisation by Pharmacogenetic testing in Inflammatory bowel disease Clinics (TOPIC) trial. For this analysis, patients without a variant in TPMT (*2, *3A or*3C) were included. Uni- and multivariate Cox-proportional hazard models were used to identify risk factors for leucopenia and infections. Leucopenia was defined as a white blood cell (WBC) count <3.0 × 109 /L and infections were classified according to the Common Terminology Criteria for Adverse Events.

RESULTS

Sixty hundred and ninety-five patients (90.6%) included in the TOPIC-trial had no variant in TPMT, of which 45 (6.5%) developed leucopenia. Median time to leucopenia was 56 (29-112) days. Multivariate analysis showed that use of mercaptopurine compared to azathioprine was associated with leucopenia (hazard ratio [HR] 2.61 [95% CIs, 1.39-4.88; P < .01]) and a higher baseline WBC count was protective (HR 0.80 [95% CIs, 0.71-0.89; P < .01]). Risk factors for infections were older age (per 10 year; HR 2.07 [95% CIs, 1.18-3.63; P = .01]) and concomitant use of biologic drugs (HR 2.15 [95% CIs, 1.14-4.07; P = .02]).

CONCLUSIONS

Low baseline WBC count and mercaptopurine, due to a relatively higher dose, were risk factors for thiopurine-induced leucopenia in patients without a TPMT variant.

Early Assessment of Thiopurine Metabolites Identifies Patients at Risk of Thiopurine-induced Leukopenia in Inflammatory Bowel Disease

BACKGROUND AND AIMS

Only a quarter of thiopurine-induced myelotoxicity in inflammatory bowel disease [IBD] patients is related to thiopurine S-methyltransferase deficiency. We determined the predictive value of 6-thioguanine nucleotide [6-TGN] and 6-methylmercaptopurine ribonucleotide [6-MMPR] concentrations 1 week after initiation [T1] for development of leukopenia during the first 8 weeks of thiopurine treatment.

METHODS

The study was performed in IBD patients starting thiopurine therapy as part of the Dutch randomized controlled TOPIC trial [ClinicalTrials.gov NCT00521950]. Blood samples for metabolite measurement were collected at T1. Leukopenia was defined by leukocyte counts of <3.0 × 10⁹/L. For comparison, patients without leukopenia who completed the 8 weeks on the stable dose were selected from the first 272 patients of the TOPIC trial.

RESULTS

Thirty-two patients with, and 162 patients without leukopenia were analysed. T1 threshold 6-TGN concentrations of 213 pmol/8 × 10⁸ erythrocytes and 3525 pmol/8 × 10⁸ erythrocytes for 6-MMPR were defined: patients exceeding these values were at increased leukopenia risk (odds ratio [OR] 6.2 [95% CI: 2.8-13.8] and 5.9 [95% CI: 2.7-13.3], respectively). Leukopenia rates were higher in patients treated with mercaptopurine, compared with azathioprine (OR 7.3 [95% CI: 3.1-17.0]), and concurrent anti-TNF therapy (OR 5.1 [95% CI: 1.6-16.4]). Logistic regression analysis of thiopurine type, threshold concentrations, and concurrent anti-tumour necrosis factor [TNF] therapy revealed that elevations of both T1 6-TGN and 6-MMPR resulted in the highest risk for leukopenia, followed by exceeding only the T1 6-MMPR or 6-TGN threshold concentration (area under the curve 0.84 [95% CI: 0.76-0.92]).

CONCLUSIONS

In ~80% of patients, leukopenia could be explained by T1 6-TGN and/or 6-MMPR elevations. Validation of the predictive model is needed before implementing in clinical practice.

Identification of Patients With Variants in TPMT and Dose Reduction Reduces Hematologic Events During Thiopurine Treatment of Inflammatory Bowel Disease

BACKGROUND & AIMS

More than 20% of patients with inflammatory bowel disease (IBD) discontinue thiopurine therapy because of severe adverse drug reactions (ADRs); leukopenia is one of the most serious ADRs. Variants in the gene encoding thiopurine S-methyltransferase (TPMT) alter its enzymatic activity, resulting in higher levels of thiopurine metabolites, which can cause leukopenia. We performed a prospective study to determine whether genotype analysis of TPMT before thiopurine treatment, and dose selection based on the results, affects the outcomes of patients with IBD.

METHODS

In a study performed at 30 Dutch hospitals, patients were assigned randomly to groups that received standard treatment (control) or pretreatment screening (intervention) for 3 common variants of TPMT (TPMT*2, TPMT*3A, and TPMT*3C). Patients in the intervention group found to be heterozygous carriers of a variant received 50% of the standard dose of thiopurine (azathioprine or 6-mercaptopurine), and patients homozygous for a variant received 0%-10% of the standard dose. We compared, in an intention-to-treat analysis, outcomes of the intervention (n = 405) and control groups (n = 378) after 20 weeks of treatment. Primary outcomes were the occurrence of hematologic ADRs (leukocyte count < 3.0*10(9)/L or reduced platelet count < 100*10(9)/L) and disease activity (based on the Harvey-Bradshaw Index for Crohn's disease [n = 356] or the partial Mayo score for ulcerative colitis [n = 253]).

RESULTS

Similar proportions of patients in the intervention and control groups developed a hematologic ADR (7.4% vs 7.9%; relative risk, 0.93; 95% confidence interval, 0.57-1.52) in the 20 weeks of follow-up evaluation; the groups also had similar mean levels of disease activity (P = .18 for Crohn's disease and P = .14 for ulcerative colitis). However, a significantly smaller proportion of carriers of the TPMT variants in the intervention group (2.6%) developed hematologic ADRs compared with patients in the control group (22.9%) (relative risk, 0.11; 95% confidence interval, 0.01-0.85).

CONCLUSIONS

Screening for variants in TPMT did not reduce the proportions of patients with hematologic ADRs during thiopurine treatment for IBD. However, there was a 10-fold reduction in hematologic ADRs among variant carriers who were identified and received a dose reduction, compared with variant carriers who did not, without differences in treatment efficacy. ClinicalTrials.gov number: NCT00521950.

Effect of maintenance immunosuppressive drugs on virus pathobiology: evidence and potential mechanisms

Recent evidence suggesting a potential anti-CMV effect of mTORis is of great interest to the transplant community. However, the concept of an immunosuppressant with antiviral properties is not new, with many accounts of the antiviral properties of several agents over the years. Despite these reports, to date, there has been little effort to collate the evidence into a fuller picture. This manuscript was developed to gather the evidence of antiviral activity of the agents that comprise a typical immunosuppressive regimen against viruses that commonly reactivate following transplant (HHV1 and 2, VZV, EBV, CMV and HHV6, 7, and 8, HCV, HBV, BKV, HIV, HPV, and parvovirus). Appropriate immunosuppressive regimens posttransplant that avoid acute rejection while reducing risk of viral reactivation are also reviewed. The existing literature was disparate in nature, although indicating a possible stimulatory effect of tacrolimus on BKV, potentiation of viral reactivation by steroids, and a potential advantage of mammalian target of rapamycin (mTOR) inhibition in several viral infections, including BKV, HPV, and several herpesviruses.