FormalPara Key Points

Interstitial pneumonitis is a classical complication of many drugs.

Pulmonary toxicity due to 5-azacytidine is rarely mentioned.

It is important to anticipate diagnosis of 5-azacitidine-associated interstitial lung disease to limit antibiotics abuse and to set up emergency treatment.

Introduction

Pneumonitis, often called interstitial lung disease or ILD, is a possible manifestation of many antineoplastic and other drugs, with several ILD subtypes being described in association with drugs. Pulmonary toxicity from 5-azacytidine, a deoxyribonucleic acid (DNA) methyltransferase inhibitor which also exerts cytotoxic effects, has rarely been reported, although the drug has been used since 1982. 5-Azacytidine acts as a hypomethylating agent of the Y globin suppressor gene to induce fetal hemoglobin in thalassemia and, since 2000, to treat high-risk myelodysplastic syndrome (MDS) and acute myelogenous leukemia (AML) with low blast counts. Here, we report a case of 5-azacytidine-asociated pneumonitis, review the literature, and develop a diagnostic algorithm for this rare condition to avoid delay in medical care and misuse of antibiotics.

Case Report

A 67-year-old woman presented as an outpatient of our Hematology Department in August 2015 for progressive neutropenia, anemia, and fatigue. Peripheral blood examination showed a normochromic normocytic anemia with 9.4 g/dL hemoglobin, 0.350 × 109/L neutrophils and 138 × 109/L platelets. A bone marrow aspirate (BMA) showed hypercellular marrow with trilineage dysplastic features, micromegakaryocytes and 13% myeloblasts. A diagnosis of refractory cytopenia with multilineage dysplasia was given, based on the WHO MDS classification [1]. A trephine biopsy was in accordance with the results from the bone marrow aspirate with 15% myeloblasts displaying dyserythropoiesis and dysmegakaryopoiesis. Karyotype G banding analysis revealed a complex cytogenetic abnormality: 46,XX,del(5)(q14q34) [2]/49,sl,+1,+9,+11 [2]/52,sd1,+11,+22,+22 [16].

Based on the above data, high-risk MDS was considered. The patient underwent appropriate tests concerning eligibility for allogenic stem cell transplantation. She received the first cycle of 5-azacytidine at the conventional dosage of 75 mg/m2 for 7 days from September 28, 2015. One week after starting 5-azacytidine, she developed moderate fever along with dry cough and, subsequently, her temperature rose to 39.5 °C. She was hospitalized on October 11, 2015. Vital signs and pulse oximetry were normal. She was placed under broad-spectrum antibiotics based on the protocol for febrile neutropenia, including ciprofloxacin 750 mg twice daily, ceftazidime 1 g three times daily (tid), and sulfamethoxazole/trimethoprim 400 mg/80 mg tid. Fever did not abate. All routine bacteriological investigations were negative. Procalcitonin levels were within the normal range. The chest and sinus radiographs were normal, as were precipitins against Aspergillus and titers against Cytomegalovirus (CMV) and Epstein-Barr virus (EBV). CMV antigenemia was negative. An interferon-γ release assay was negative. Marrow re-aspiration revealed a 22% increment of blast number, suggesting a transformation towards acute myeloid leukemia. During her second week in hospital, the patient complained of dyspnea on October 22, 2015. Blood gas showed a PaO2 of 59 mmHg and PaCO2 of 29 mmHg. Pulse oxygen saturation was 91% (room air). High-resolution computed tomography (HRCT) of the chest disclosed diffuse bilateral opacities with ground-glass shadowing and pleural effusion bilaterally (Fig. 1). Mediastinal and hilar lymph nodes were moderately enlarged. The patient was transferred to the intensive care unit on October 23 for bronchoalveolar lavage (BAL), which showed 170 red blood cells/mm3 and 10 white blood cells/mm3. Polymerase chain reaction (PCR) for Mycobacterium tuberculosis, Pneumocystis jiroveci, and CMV were negative. Immunofluorescence test for Pneumocystis was also negative. Cultures including viral and fungal were all negative. The patient was maintained on antibiotics. A diagnosis of drug-induced pneumonitis was considered and, given the negative BAL in terms of an infection, corticosteroid therapy was given at a dose of 1 mg/kg body weight on October 28. Within 4 days, a significant improvement in clinical status and imaging was noted. A repeat chest computed tomography (CT) scan at 1 week also showed significant improvement. Temperature was normal and C-reactive protein returned to normal within 1 week. Following 2 days of quick steroid tapering, the patient again developed fever. Left upper chest pain corresponding to lobulated pleural effusion was noted and 1200 mL of serosanguinous fluid was removed via chest tube. Pleural fluid was a predominantly neutrophilic exudate containing 4 g/dL proteins. Corticosteroids were maintained and antibiotics were discontinued. The patient remained afebrile and was discharged from hospital on November 9. She eventually received a haploidentical bone marrow transplant on December 23, 2015.

Fig. 1
figure 1

High-resolution computed tomography of the chest disclosed diffuse bilateral interstitial opacities with ground-glass shadowing, and pleural effusion bilaterally

Full size image

Discussion

Clinical features of 5-azacytidine-associated ILD include cough, dyspnea, pleuritic chest pain, and hypoxemic respiratory failure [2]. Like many antineoplastic agent-induced lung diseases, prominent imaging findings include diffuse multifocal ground-glass shadowing, interstitial thickening, and pleural effusion.

Here we review 12 earlier cases of 5-azacytidine-associated pneumonitis (Table 1). Delayed diagnosis following failure of broad-spectrum antibiotic therapy was common [3–14]. Corticosteroids were used depending on severity.

Table 1 Clinical characteristics, examination, and treatment of myelodysplastic syndrome and acute myeloid leukemia patients with 5-azacitidine-induced interstitial lung disease
Full size table

The diagnosis of drug-induced pneumonitis rests on history of drug exposure, clinical imaging, bronchoalveolar lavage, exclusion of other lung conditions, improvement following drug discontinuation, and recurrence of symptoms upon rechallenge with the drug. In the present case, we were reluctant to readminister the drug as the risk of doing so is poorly known. The Naranjo probability score in this case was 6, consistent with probable adverse reaction [15, 16]. In our case, despite steroid use, symptoms relapsed and were characterized as serosanguinous pleural effusion. Serosanguinous pleural exudates with polymorphonuclear leukocyte predominance without bacteriological evidence of infection may be a manifestation of pleurisy such as in lupus erythematosus, which might be induced by the drug in question [17].

Mechanisms for drug-induced ILD are direct cytotoxicity, hypersensitivity, oxidative stress, release of cytokines and thus pyrogens, and lastly impaired repair by type II pneumocytes. Chronology of events, unexplained fever, and steroid response to clinical and radiological signs constitute a hypersensitivity pneumonitis.

5-Azacytidine is a cytosine analog, a potent inhibitor of DNA methyltransferase, with a hypomethylating effect in vivo and in vitro. Unlike gemcitabine, although cytotoxic at high dose, at low dose it is capable of inducing differentiation and hypomethylation. Hence, profound myelosuppression or direct lung injury like capillary leak syndrome is not encountered during 5-azacytidine toxicity. The role of oxidative stress is still unclear although there are a few reports concerning induction of necrosis in vitro by 5-azacytidine [18]. Oxidative stress could contribute to T-cell response by inhibiting the ERK pathway signaling in T cells. Recently we observed drug-associated ILD in two patients treated with an experimental inhibitor of DNA methyltransferase, suggesting a common class effect [19, 20].

Unlike oxaliplatin, anaphylactic reaction is extremely rare in 5-azacytidine. Few patients develop symptoms during the administration of chemotherapy. Although an elevated IgE level was reported in one case by Nair et al., the evidence is not sufficient to conclude a type I reaction [8]. Most patients develop symptoms within a week to a month after administration of 5-azacytidine. Although the histopathological evidence is rarely possible in immunocompromised patients with hematological malignancy, Sekhri et al. presented a bronchocentric granuloma in their report [7]. Hence, another plausible explanation could be a delayed type of hypersensitivity (type IV) with activation of CD8 T cell, which could explain most of the symptoms. This could possibly occur during a relative immune reconstitution phase of an immunocompromised patient.

The pulmonary fibrosis may be due to DNA hypomethylation causing direct upregulation of type I collagen synthesis. Sanders et al. suggested that the DNA methylation is important in idiopathic pulmonary fibrosis (IPF), as an altered DNA methylation profile has been demonstrated in their experiment [21]. Moreover, there are reports suggesting the epigenetic priming by 5-azacytidine confers transdifferentiating properties to various cells. However, it is difficult to establish a relationship at present [22].

Our diagnostic algorithm is based on that of drug-induced interstitial lung disease (DILD), and is not specific for 5-azacytidine (Fig. 2). Any febrile condition in those patients with worsening pulmonary symptoms despite broad-spectrum antibiotics should arouse suspicion of DILD. HRCT and BAL are crucial as 5-azacytidine-induced pneumonitis remains a diagnosis of exclusion, like many other DILDs. Some nonspecific immunological tests could be helpful, like levels of p-ANCA (antineutrophil cytoplasmic antibody) and ANA (antinuclear antibody). Prompt consultation with a pulmonary care unit is of utmost utility.

Fig. 2
figure 2

Decision algorithm for 5-azacitidine-induced ILD

Full size image

Conclusions

A high degree of vigilance is advised to entertain the diagnosis in a timely manner, since the condition can be fatal. We now utilize a decision algorithm in order for timely diagnosis of 5-azacitidine-induced ILD to limit antibiotics abuse and to set up emergency treatment.