Corticosteroid-responsive interstitial pneumonitis related to imantinib mesylate with successful rechallenge, and potential causative mechanisms

Imatinib-induced irreversible interstitial lung disease: A case report

RATIONALE

Imatinib mesylate (imatinib) is a classic tyrosine kinase inhibitor used to treat chronic myeloid leukemia. Although it is well tolerated by most patients and helps in the achievement of complete remission, a few rare imatinib-associated adverse effects such as pulmonary interstitial fibrosis have been reported. Because of its rareity, the clinical features of imatinib-induced interstitial lung disease (ILD) remain unclear.

PATIENT CONCERNS

A 49-year-old Chinese man with chronic myeloid leukemia received oral treatment with imatinib and initially exhibited a good response. However, he presented with cough and fever 9 months after treatment initiation.

DIAGNOSES

Pulmonary computed tomography indicated diffuse interstitial fibrosis in both lungs. All tests for possible infectious pathologies provided negative results.

INTERVENTIONS

The patient was diagnosed with interstitial pneumonia and treated with antibiotics; however, there was no improvement. On the basis of a suspicion of imatinib-induced ILD, imatinib was discontinued and prednisone treatment was initiated.

OUTCOMES

The patient's symptoms ameliorated with treatment, and imatinib was reintroduced. However, he developed cough and dyspnea again, and his treatment was switched to nilotinib as a second-line regimen. He was regularly monitored, and although his clinical symptoms ameliorated, computed tomography performed 29 months after he was diagnosed with ILD showed irreversible pulmonary interstitial fibrosis without progression.

LESSONS

Clinicians should consider the possibility of severe irreversible ILD and carefully monitor patients receiving imatinib treatment.

Tyrosine Kinase Inhibitor-Induced Interstitial Lung Disease: Clinical Features, Diagnostic Challenges, and Therapeutic Dilemmas

Since the approval of the first molecularly targeted tyrosine kinase inhibitor (TKI), imatinib, in 2001, TKIs have heralded a new era in the treatment of many cancers. Among their innumerable adverse effects, interstitial lung disease (ILD) is one of the most serious, presenting most frequently with dyspnea, cough, fever, and hypoxemia, and often treated with steroids. Of the 28 currently approved TKIs, 16 (57 %) are reported to induce ILD with varying frequency and/or severity. The interval from drug administration to onset of ILD varies between patients and between TKIs, with no predictable time course. Its incidence is variously reported to be approximately 1.6-4.3 % in Japanese populations and 0.3-1.0 % in non-Japanese populations. The mortality rate is in the range of 20-50 %. Available evidence (primarily following the use of erlotinib and gefitinib in Japan because of the unique susceptibility of that population) has identified a number of susceptibility and prognostic risk factors (male sex, a history of smoking, and pre-existing pulmonary fibrosis being the main ones). Although the precise mechanism is not understood, collective evidence suggests that immune factors may be involved. If TKI-induced ILD is confirmed by thorough evaluation of the patient and exclusion of other causes, management is supportive, and includes discontinuation of the culprit TKI and administration of steroids. Discontinuing the culprit TKI presents a clinical dilemma because the diagnosis of TKI-induced ILD in a patient with pre-existing pulmonary fibrosis can be challenging, the patient may have TKI-responsive cancer with no suitable alternative, and switching to an alternative agent, even if available, carries the risk of the patient experiencing other toxic effects. Preliminary evidence suggests that therapy with the culprit TKI may be continued under steroid cover and/or at a reduced dose. However, this approach requires careful individualized risk-benefit analysis and further clinical experience.

Pleuropulmonary Changes Induced by Drugs in Patients with Hematologic Diseases

Patients with hematologic diseases who are being treated with therapy drugs, or receive radiation therapy or blood transfusions may develop a host of potentially fatal infectious and noninfectious pulmonary complications [1]. The increased complexity of multimodality and high-dose treatment regimens with the intended benefit of augmented antineoplastic efficacy and prolonged disease-free survival, the use of a panel of novel drugs to treat malignant and nonmalignant hematologic conditions (e.g., azacytidine, bortezomib, cladribine, dasatinib, fludarabine, imatinib, lenalidomide, rituximab, and thalidomide), total body irradiation (TBI) and hematopietic stem cell transplantation (HSCT) have increased the incidence of severe sometimes life-threatening pulmonary complications.

Reduced vancomycin susceptibility in Staphylococcus aureus, including vancomycin-intermediate and heterogeneous vancomycin-intermediate strains: resistance mechanisms, laboratory detection, and clinical implications

The emergence of vancomycin-intermediate Staphylococcus aureus (VISA) and heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) over the past decade has provided a challenge to diagnostic microbiologists to detect these strains, clinicians treating patients with infections due to these strains, and researchers attempting to understand the resistance mechanisms. Recent data show that these strains have been detected globally and in many cases are associated with glycopeptide treatment failure; however, more rigorous clinical studies are required to clearly define the contribution of hVISA to glycopeptide treatment outcomes. It is now becoming clear that sequential point mutations in key global regulatory genes contribute to the hVISA and VISA phenotypes, which are associated predominately with cell wall thickening and restricted vancomycin access to its site of activity in the division septum; however, the phenotypic features of these strains can vary because the mutations leading to resistance can vary. Interestingly, changes in the staphylococcal surface and expression of agr are likely to impact host-pathogen interactions in hVISA and VISA infections. Given the subtleties of vancomycin susceptibility testing against S. aureus, it is imperative that diagnostic laboratories use well-standardized methods and have a framework for detecting reduced vancomycin susceptibility in S. aureus.

Vancomycin MIC plus heteroresistance and outcome of methicillin-resistant Staphylococcus aureus bacteremia: trends over 11 years

Vancomycin MICs (V-MIC) and the frequency of heteroresistant vancomycin-intermediate Staphylococcus aureus (hVISA) isolates are increasing among methicillin (meticillin)-resistant Staphylococcus aureus (MRSA) isolates, but their relevance remains uncertain. We compared the V-MIC (Etest) and the frequency of hVISA (Etest macromethod) for all MRSA blood isolates saved over an 11-year span and correlated the results with the clinical outcome. We tested 489 isolates: 61, 55, 187, and 186 isolates recovered in 1996-1997, 2000, 2002-2003, and 2005-2006, respectively. The V-MICs were < or = 1, 1.5, 2, and 3 microg/ml for 74 (15.1%), 355 (72.6%), 50 (10.2%), and 10 (2.1%) isolates, respectively. We detected hVISA in 0/74, 48/355 (13.5%), 15/50 (30.0%), and 8/10 (80.0%) isolates with V-MICs of < or = 1, 1.5, 2, and 3 microg/ml, respectively (P < 0.001). The V-MIC distribution and the hVISA frequency were stable over the 11-year period. Most patients (89.0%) received vancomycin. The mortality rate (evaluated with 285 patients for whose isolates the trough V-MIC was > or = 10 microg/ml) was comparable for patients whose isolates had V-MICs of < or = 1 and 1.5 microg/ml (19.4% and 27.0%, respectively; P = 0.2) but higher for patients whose isolates had V-MICs of > or = 2 microg/ml (47.6%; P = 0.03). However, the impact of V-MIC and hVISA status on mortality or persistent (> or = 7 days) bacteremia was not substantiated by multivariate analysis. Staphylococcal chromosome cassette mec (SCCmec) typing of 261 isolates (including all hVISA isolates) revealed that 93.0% of the hVISA isolates were SCCmec type II. These findings demonstrate that the V-MIC distribution and hVISA frequencies were stable over an 11-year span. A V-MIC of > or = 2 microg/ml was associated with a higher rate of mortality by univariate analysis, but the relevance of the V-MIC and the presence of hVISA remain uncertain. A multicenter prospective randomized study by the use of standardized methods is needed to evaluate the relevance of hVISA and determine the optimal treatment of patients whose isolates have V-MICs of > or = 2.0 microg/ml.

Characterization of vancomycin-heteroresistant Staphylococcus aureus from the metropolitan area of Detroit, Michigan, over a 22-year period (1986 to 2007)

We screened for heteroresistant, vancomycin-intermediate Staphylococcus aureus (hVISA) among clinical isolates of methicillin-resistant S. aureus collected from three hospitals (two urban teaching hospitals and one community hospital) in the Detroit metropolitan area over a 22-year period. The Macro Etest method was used to screen all available isolates. Confirmation of hVISA-positive screens were confirmed by population-area under the concentration-time curve (AUC) analysis. A total of 1,499 isolates revealed hVISA/VISA rates of 2.2/0.4% (n = 225; 1986 to 1993), 7.6/2.3% (n = 356; 1994 to 2002), and 8.3/0.3% (n = 917; 2003 to 2007). Population-AUC analysis confirmed 92.6% of the hVISA-positive strains determined by the Macro Etest method. For the isolates with known sources (1,208), the predominant source of hVISA was blood (60%), followed by lung (21%), skin and wound infections (14%), abscess (1%), and other (4%). The percentage of hVISA-positive strains appeared to increase as a function of the vancomycin MIC. Staphylococcal cassette chromosome mec (SCCmec) typing revealed that the majority (56.9%) of the hVISA strains were SCCmec type II and 39.4% were type IV; the majority of these strains were collected from 2000 to 2007. Our data indicate that the prevalence of hVISA may be increasing. Based on the association of vancomycin treatment failure in patients with hVISA, surveillance of hVISA strains is warranted.

Evaluation of a new Etest vancomycin-teicoplanin strip for detection of glycopeptide-intermediate Staphylococcus aureus (GISA), in particular, heterogeneous GISA

Glycopeptide-intermediate Staphylococcus aureus (GISA) and, in particular, heterogeneous GISA (hGISA) are difficult to detect by standard MIC methods, and thus, an accurate detection method for clinical practice and surveillances is needed. Two prototype Etest strips designed for hGISA/GISA resistance detection (GRD) were evaluated using a worldwide collection of hGISA/GISA strains covering the five major clonal lineages. A total of 150 strains comprising 15 GISA and 60 hGISA strains (defined by population analysis profiles-area under the curve [PAP-AUC]), 70 glycopeptide-susceptible S. aureus (GSSA) strains, and 5 S. aureus ATCC reference strains were tested. For standardized Etest vancomycin (VA) MIC testing, the modified Etest macromethod with VA and teicoplanin (TP) strips tested with a heavier inoculum using brain heart infusion agar (BHI) and two glycopeptide screening agar plates (6 microg/ml VA/BHI and 5 microg/ml Mueller-Hinton agar [MHA]) were tested in parallel with the two new Etest GRD strips: a VA 32 (0.5-microg/ml)-TP 32 (0.5-microg/ml) double-sided gradient (E-VA/TP) with one prototype overlaid with a nutrient (E-VA/TP+S) to enhance the growth of hGISA. The Etest GRD strips were tested with a standard 0.5-McFarland standard inoculum using MHA and MHA plus 5% blood (MHB) and were read at 18 to 24 and 48 h. The interpretive MIC cutoffs used for the new Etest GRD strips at 24 and 48 h were as follows: for GISA, TP or VA, >or=8, and a standard VA MIC of >or=6; for hGISA, TP or VA, >or=8, and a standard VA MIC of <or=4. The results on MHB at 48 h showed that E-VA/TP+S had high specificity (94%) and sensitivity (95%) in comparison to PAP-AUC and was able to detect all GISA (n = 15) and 98% of hGISA (n = 60) strains. In contrast, the glycopeptide screening plates performed poorly for hGISA. The new Etest GRD strip (E-VA/TP+S), utilizing standard media and inocula, is a simple and acceptable tool for detection of hGISA/GISA for clinical and epidemiologic purposes.

Infiltrative lung diseases: complications of novel antineoplastic agents in patients with hematological malignancies

Infiltrative lung disease is a well-known complication of antineoplastic agents in patients with hematological malignancies. Novel agents are constantly being added to available treatments. The present review discusses different pulmonary syndromes, pathogenesis and management of these novel agents.

Pulmonary complications of novel antineoplastic agents for solid tumors

Antineoplastic agent-induced pulmonary toxicity is an important cause of respiratory failure. Although the incidence of antineoplastic agent-induced pulmonary toxicity seems to be low, more cases can be expected, with increasing numbers of patients receiving the new generations of antineoplastic agents. Antineoplastic agents have previously been associated with bronchospasm, hypersensitivity reactions, venous thromboembolism, and pulmonary hemorrhage. Physicians should be aware of the clinical and radiographic presentations of the pulmonary toxicities associated with the newer antineoplastic agents. The approach to diagnosis, risk factors, and possible mechanisms of antineoplastic agent-induced pulmonary toxicity are discussed in this article.

Functional characterization of TcaA: minimal requirement for teicoplanin susceptibility and role in Caenorhabditis elegans virulence

The inactivation of TcaA contributes to intrinsic teicoplanin resistance in experimental and clinical isolates of glycopeptide-intermediate resistant Staphylococcus aureus. PhoA fusions confirmed that TcaA is a transmembrane protein with a short intracellular N-terminal domain containing a C-4 zinc finger binding motif, a single membrane-spanning domain, and a large extracellular C-terminal domain. The region conferring teicoplanin susceptibility was narrowed down to the transmembrane part and the first third of the extracellular domain of TcaA, suggesting that neither the C-4 zinc finger binding motif nor the C terminus contributed to teicoplanin susceptibility. TcaA belongs to the cell wall stress stimulon, which comprises a set of genes universally upregulated by cell wall damage. Induction of tcaA was shown to be fully dependent on the two-component regulatory system VraSR. A 66-bp region upstream of the transcriptional start site, which contained an inverted repeat partially covering the promoter box, was shown to be essential for VraSR-mediated induction by cell wall stress. Interestingly, the induction or overexpression of tcaA did not contribute further to teicoplanin susceptibility, suggesting that small amounts of TcaA, such as those present under normal uninduced conditions, were sufficient for TcaA-mediated teicoplanin susceptibility. The strong attenuation of tcaA deletion mutants in a Caenorhabditis elegans survival assay suggested that TcaA may, in addition to affecting glycopeptide susceptibility, also play a role in virulence.

Emerging Safety Issues with Imatinib and Other Abl Tyrosine Kinase Inhibitors

Imatinib and other Abl tyrosine kinase inhibitors (TKIs), such as dasatinib and nilotinib, have significantly improved the outcome of patients with chronic myeloid leukemia. Imatinib and dasatinib are currently Food and Drug Administration (FDA) approved, and nilotinib is expected to gain FDA approval soon. In addition, several other Abl TKIs are being evaluated in various clinical trials. Imatinib has also shown efficacy in the therapy of gastrointestinal stromal tumors, Philadelphia chromosome-positive acute lymphocytic leukemia and hypereosinophilic syndrome. Because of their efficacy, more patients will receive Abl TKIs for a longer period of time. Imatinib was FDA approved after a short follow-up because of its exceptional efficacy and safety profile. The most common adverse events reported included fluid retention, fatigue, diarrhea, and muscle cramps. With longer follow-up, issues related to the long-term use of imatinib have been discussed. Our aim is to review the emerging safety issues of Abl TKIs after a longer follow-up.

Management of metastatic gastrointestinal stromal tumour in the Glivec era: a practical case-based approach

Gastrointestinal stromal tumour is now recognized as a distinct pathological malignancy and has received much attention over the last few years. Despite almost universal resistance to chemotherapy, a novel therapy, Imatinib, which targets the KIT receptor, has changed the natural history of this disease. We have audited the first 26 consecutive patients with gastrointestinal stromal tumour treated over 4 years at a single institution. A practical guide to the management of common toxicities and drug resistance is reported with a review of the published reports. Many of the strategies used are likely to be widely applicable to the use of targeted therapies in other malignancies.

Role of Allogeneic Stem Cell Transplantation for Adult Chronic Myeloid Leukemia in the Imatinib Era

Due to superior survival in the short to medium term, the first-generation ABL kinase inhibitor imatinib mesylate has generally supplanted all other therapies as the initial treatment of choice in chronic phase chronic myeloid leukemia. The role of allogeneic stem cell transplantation (alloSCT) has shifted from a preferred first-line therapy to a possible second- or third-line therapy. However, despite generally excellent responses to imatinib, some patients respond poorly or lose response, and the risk-benefit equation in these cases may rapidly shift in favor of the alloSCT option. These patients need to be identified as soon as possible so that the alloSCT option can be applied while they are still in controlled chronic phase. Monitoring of imatinib response in patients who have suitable donors and are potentially eligible for alloSCT needs to be frequent, sensitive, and accurate. Clear criteria for switching from imatinib therapy to the alloSCT option should be established for each patient according to the specific risk profile of the transplant. The potential efficacy and safety of clinical trials combining reduced intensity alloSCT with ABL kinase inhibitor therapy warrants further consideration.