Disseminated Infections with Talaromyces marneffei in Non-AIDS Patients Given Monoclonal Antibodies against CD20 and Kinase Inhibitors

Clinicians should be aware of these infections, especially in patients from disease-endemic regions.

Infections with the fungus Talaromyces (formerly Penicillium) marneffei are rare in patients who do not have AIDS. We report disseminated T. marneffei infection in 4 hematology patients without AIDS who received targeted therapy with monoclonal antibodies against CD20 or kinase inhibitors during the past 2 years. Clinicians should be aware of this emerging complication, especially in patients from diseaseendemic regions.
T alaromyces (formerly Penicillium) marneffei is a pathogenic, thermal dimorphic fungus that causes systemic mycosis in Southeast Asia. T. marneffei infection is characterized by fungal invasion of multiple organ systems, especially blood, bone marrow, skin, lungs, and reticuloendothelial tissues, and is highly fatal, especially when diagnosis and treatment are delayed (1,2). This disease is found predominantly in AIDS patients and occasionally those with cell-mediated immunodeficiencies involving the interleukin-12/interferon-γ (IFN-γ) signaling pathway, such as congenital STAT1 mutations or acquired autoantibodies against IFN-γ (1, [3][4][5][6]. The infection has rarely been reported among hematology patients, including those from disease-endemic regions (7,8).
At Queen Mary Hospital in Hong Kong, a 1,600-bed university teaching hospital that has a hematopoietic stem cell transplantation service, where a wide range of invasive fungal infections have been observed (9,10), only 3 cases of T. marneffei infection were encountered in >2,000 hematology patients in the past 20 years, despite the longstanding availability of mycologic culture and serologic testing (7,8,11,12). In contrast, the infection was commonly reported among AIDS patients (13).
In the past 2 years, we have been alerted by 4 unprecedented cases of disseminated T. marneffei infection among non-AIDS hematology patients given targeted therapies, including monoclonal antibodies (mAbs) against CD20 and kinase inhibitors, which are being increasingly used in recent years. We report details for these 4 hematology case-patients. The study was approved by the institutional review board of The University of Hong Kong/Hospital Authority Hong Kong West Cluster in Hong Kong.

Case-Patient 1
Patient 1 was a 56-year-old Filipino man with Waldenström macroglobulinemia, idiopathic thrombocytopenic purpura, and primary biliary cirrhosis. He had fever, night sweating, productive cough, and left facial pain for 1 week and bloody diarrhea for 2 days. He had previously received fludarabine, dexamethasone, and rituximab (mAb against CD20, 18 months earlier) for treatment of Waldenström macroglobulinemia ( Table 1). The idiopathic thrombocytopenic purpura was controlled with intravenous immunoglobulin and maintenance prednisolone and mycophenolate sodium. A chest radiograph showed a small cavitary lesion in the right lower lobe. His symptoms and signs did not resolve after he received empirical intravenous imipenem/cilastatin and metronidazole (Table 2).
A colonoscopy showed multiple shallow ulcers at the terminal ileum ( Figure 1). Histologic analysis of an ulcer biopsy specimen showed slough of an acutely inflamed ulcer but no microorganisms. However, histologic analysis of a specimen from a nasopharyngeal biopsy performed for persistent left facial pain showed abundant yeast cells engulfed by foamy macrophages (Figure 2). Culture of terminal ileal ulcer biopsy specimens, stool samples, and nasopharyngeal biopsy specimens yielded T. marneffei. A contrast-enhanced cranial computed tomography (CT) scan showed 2 lesions (3-4-mm) with rim enhancement and perifocal edema at the right occipital and left parietooccipital lobes. A thoracic CT scan showed 2 cavitary lesions (4-8 mm) in the right upper and lower lobes.
Immunologic testing showed that the patient was negative for HIV and autoantibodies against IFN-γ. His CD3+ and CD8+ counts were within references ranges, but he had mild CD4+ lymphopenia ( Table 2). His fever and symptoms resolved with after 2 weeks of treatment with intravenous liposomal amphotericin B, followed by oral voriconazole. Reassessment colonoscopy (at 2 months) and CT scan (at 6 months) showed complete resolution of all lesions.

Case-Patient 2
Patient 2 was a 44-year-old Chinese man who had fever for 2 days. He had previously received chemotherapy and mAbs against CD20 (rituximab, 14 months earlier; obinutuzumab, concomitant) for refractory chronic lymphocytic leukemia (CLL) involving bone marrow (Table 1). He was empirically given intravenous piperacillin/tazobactam and anidulafungin ( Table 2). Histologic analysis of a trephine biopsy specimen showed persistent CLL with plasmacytic differentiation, and Grocott staining showed yeasts with central septa in small clusters. Culture of peripheral blood and bone marrow aspirate yielded T. marneffei. A change in antifungal treatment to intravenous amphotericin B led to defervescence and clearance of fungemia. He was given oral itraconazole as maintenance therapy. He remained well until 2 months later when he was hospitalized for deteriorating CLL complicated by neutropenic fever with multiorgan failure caused by other opportunistic infections (Table 1). He died 5 months after the episode of disseminated T. marneffei infection.

Case-Patient 3
Patient 3 was a 63-year-old Chinese man with myelofibrosis and well-controlled diabetes mellitus. He had intermittent fever, right cervical lymphadenopathy, and productive cough for 4 months. He was given ruxolitinib (kinase inhibitor) 6 months before symptom onset because of transfusion-dependent myelofibrosis despite splenectomy 4 years earlier (Table 1). A chest radiograph and thoracic CT scan showed multiple cavitary lesions and consolidation. Bronchoalveolar lavage was negative for bacteria, fungi, and mycobacteria. A serum cryptococcal antigen test result was negative. He was empirically given intravenous imipenem/cilastatin and oral doxycycline, but his symptoms persisted. A right cervical lymph node culture yielded T. marneffei. His symptoms and radiologic abnormalities resolved after treatment with intravenous amphotericin B for 2 weeks, followed by oral voriconazole for 6 months.

Case-Patient 4
Patient 4 was a 67-year-old Chinese man with acute myeloid leukemia and hypertension. He had fever and malaise for 2 days without localizing signs. He had been given sorafenib (kinase inhibitor) 8 months earlier for chemotherapy-refractory acute myeloid leukemia (Table 1). His fever did not respond to intravenous meropenem. Subsequently, †Time interval between end of therapy and onset of symptoms for T. marneffei infection.
2 sets of blood cultures yielded T. marneffei. He was given intravenous amphotericin B for 2 weeks, followed by oral voriconazole. He remained well at follow-up 6 months after symptom onset.

Discussion
T. marneffei infection is an emerging complication in hematology patients receiving targeted therapies. Historically, T. marneffei infection has rarely been seen in non-AIDS patients, even in disease-endemic regions. During 1994-2014, only 3 other cases were observed in our hematology patients (7,8,11   in the number of hematology patients in our hospital. Therefore, these 4 cases indicate an increase in the incidence of T. marneffei infection in these patients. Although other immunosuppressants given to case-patients 1, 2, and 4 might have contributed to overall immunosuppression, none of these immunosuppressants, which have been used for years, have been associated with T. marneffei infection. Because use of targeted therapies is increasing in diverse patient groups, clinicians should be aware of this emerging complication, especially in patients from disease-endemic regions who have received these therapies with other immunosuppressants. The exact mechanisms through which these targeted therapies lead to T. marneffei infection remain incompletely understood. Rituximab and obinutuzumab (used by case-patients cases 1 and 2) are mAbs against CD20 that predominantly target B cells. Unlike T cells, the role of B cell-mediated humoral response in T. marneffei infection is poorly defined. Although case-patient 1 had mild CD4+ lymphopenia probably related to concomitant use of prednisolone and mycophenolate sodium, T. marneffei infection is rarely seen in patients with CD4+ counts >300/ µL (1). We postulate that B cell dysfunction might have impaired production of neutralizing antibodies against key virulence factors of T. marneffei or might involve impairment of cytokine-producing B cells, which are essential for T helper cell function (14).
More severe infections with fungemeia and bone marrow involvement developed in case-patients 2 and 4, who had undetectable levels of serum antibodies against T. marneffei. Correspondingly, case-patients 1 and 3, who had antibody titers >1:320, did not have positive blood culture results (Table). Symptoms developed in casepatient 1 more than a 1 year after he completed therapy with mAbs against CD20. This finding might be related to long-lasting B cell-depleting effects of mAbs against CD20 (15).
Regarding kinase inhibitors (used by cases-patients 3 and 4), ruxolitinib is a selective Janus kinase (JAK)-1/2 inhibitor that prevents signal transduction for type I/II cytokines, including IF N-γ, by interfering with the JAK-STAT signaling pathway. Use of ruxolitinib has been associated with opportunistic infections caused by intracellular pathogens, such as Mycobacterium tuberculsosis and Cryptococcus neoformans (16,17). Similarly, patients with impaired JAK-STAT signaling, but not those with diabetes mellitus or splenectomy (case-patient 3), are predisposed to T. marneffei infection (6). Sorafenib is a multikinase inhibitor with various immunomodulatory effects, including impaired T-cell response and proliferation and reduced IFN-γ production (18). These immune defects have been associated with reactivation of latent tuberculosis and might also predispose patients to opportunistic infections caused by intracellular organisms such as T. marneffei (18).
The recognition of disseminated T. marneffei infection as an emerging complication in non-AIDS patients treated with targeted therapy has major public health implications.  In regions to which T. marneffei infection is endemic, serologic surveillance for patients receiving targeted therapy might be useful in the early diagnosis of T. marneffei infection, as in the case of AIDS patients (19). In non-endemic regions, such as the United States, clinicians should be vigilant of this infrequent infection in at-risk hematology patients who have resided in or are returning from diseaseendemic areas.