In our study, voriconazole was found to be effective as a primary therapy for CPA; global success was observed in 32 and 44 % of patients at 6 months and at ≥6 months of treatment, respectively. CPA was controlled according to radiological assessments in 97 % of patients, i.e., in all those with CNPA and 94 % of those with CCPA. There were also statistically significant improvements in some CPA-related symptoms (cough and sputum production), which may more closely reflect improvements in the inflammatory processes due to Aspergillus infection.
This is the first study of antifungal therapy for CPA with an extensive follow-up period to demonstrate a quality-of-life improvement in patients with severe underlying lung diseases and comorbid conditions. Prolonged voriconazole therapy was well tolerated, with adverse events either related to the underlying pathology or consistent with the known side-effect profile of voriconazole [20]. Photosensitivity reactions occurred in almost 20 % of patients in this study.
The global success rates for CPA were similar at 3 (29 %) and 6 (32 %) months following treatment with voriconazole, suggesting that treatment for 3 months could be sufficient for some patients, especially those with CNPA. Indeed, treatment outcome was more frequently favorable and achieved more rapidly in patients with necrotizing forms of CPA than in those with CCPA. This could be due to the fungus having been more exposed to voriconazole in CNPA than CCPA. Aspergillosis infection develops within parenchymal lung tissue in CNPA, whereas it exists within a cavity surrounded by fibrotic tissue in CCPA [1], thus potentially hindering the penetration of antifungals into the site of infection. The marked increase in response rate among CCPA patients from the 6-month visit to EOT suggests that a longer duration of treatment (>6 months) may be necessary in patients with cavitary forms of CPA.
Three relapses were observed at the 6-month follow-up visit, one each in patients with CNPA, CCPA, and TBA. In the CNPA patient, fungal isolates obtained at initial diagnosis and at relapse were different as judged by multilocus microsatellite analysis (data not shown) [21]. This suggests that the relapse was due to reinfection with a new strain and not reactivation of the primary infection.
At baseline, only one strain was found to exhibit pan-azole resistance (i.e., including voriconazole) among the 32 strains tested. In contrast, resistance to itraconazole (23 %) and amphotericin B (38 %) were common. The high number of amphotericin B-resistant strains was unexpected. This patient population is rarely treated with amphotericin B and no previous treatment with amphotericin B was reported in the present study population, although we cannot exclude this possibility with complete certainty. It has been suggested that the Etest may be better able to differentiate between amphotericin B-susceptible and -resistant strains than traditional broth microdilution methods [22]. This may explain, at least in part, the high number of resistant strains observed in the present study.
Both resistance to antifungals and pre-existing pulmonary disease may have been important determinants of the overall outcome in our study. As mentioned above, it was not possible to evaluate the effect of antifungal resistance, as there was only one strain with an elevated MIC to voriconazole. Underlying pulmonary diseases were inherent to our study population and the outcome could have been influenced by the progression of the underlying pulmonary condition rather than therapeutic failure. Other factors may also have influenced outcome, such as concomitant corticosteroid therapy, as shown by the lower success rate in these patients.
Our findings are consistent with other published observations of oral voriconazole used in this setting [15–17] and support the current recommendations of the Infectious Diseases Society of America (IDSA), which give voriconazole a B grading for CPA therapy in general and CNPA in particular [23]. Our efficacy results compare favorably, in terms of treatment success, relapse rate, and radiological response, with those from prospective clinical trials with oral itraconazole for CNPA and aspergilloma [6, 24]. However, unlike our own study, these trials classified CPA disease stabilization as a treatment success, which further underscores the potential efficacy differences between voriconazole and itraconazole. Furthermore, diagnostic criteria, evaluation of efficacy, and study endpoints were not clearly defined in the itraconazole studies [6, 24].
The other antifungals evaluated in this setting were oral posaconazole and intravenous micafungin [25–28]; data with intravenous amphotericin B are available, but are sparse and discouraging. In a retrospective case series, posaconazole exhibited a response rate of 61 and 46 % at 6 and 12 months, respectively, where a successful response was defined as no clinical and/or radiological deterioration, and, as such, included stable disease [25]. Micafungin was evaluated in a retrospective case series, a prospective, non-comparative study, and a comparative trial with voriconazole [26–28]. Although these studies suggest good tolerability and efficacy of micafungin in the treatment of CPA, the results need to be interpreted with caution. For instance, treatment duration was short (maximum of 8 weeks in the open-label study and 4 weeks in the comparative study). Furthermore, treatment success was defined by subjective criteria, such as clinical improvement, decreased plasma levels of inflammatory markers, and “…apparent improvement in the newly appeared lesions on radiological images” [26–28].
Our trial had some limitations which should be considered when interpreting the study findings. A comparator or control group was not included in our study. Our study also did not include therapeutic drug monitoring or long-term data on relapses/recurrences or survival status beyond the 6-month follow-up period. However, the study had several strengths compared with previous studies of voriconazole and other antifungals in this setting, such as the prospective study design, efficacy assessment based on imaging confirmed by a data review committee, treatment duration of 6–12 months, and a definition of global success that included only complete and partial radiological responses.
This is the first prospective, multicenter study with a central review of predefined radiological response criteria to demonstrate the effectiveness of voriconazole therapy in patients with CPA, particularly those with CNPA. Favorable treatment response was observed from 3 months onwards in CNPA patients, but improvement required at least 6–12 months in CCPA patients. Future studies should evaluate the value of voriconazole dose adjustments based on plasma levels, an approach associated with potential improvements in the efficacy and safety of voriconazole for invasive aspergillosis [29].