Screening Efectiveness with SERUM Galactomannan in High and Low Risk Patients for Fungal Infection in the Post ALLO-HTC

Background and aims: Serum galactomannan (GM) is used as a screening test for the early diagnosis of Aspergillus infection in high risk patients for fungal invasive infection. Serial GM levels analysis have proven to be useful in the high risk clinical setting patients, specially when neutropenic and not receiving anti-mold agents prophylaxis. There is a lack of information regarding the benefit of GM in patients undergoing allogeneic hematopoietic cell transplant (HCT). The aim of this work is to measure the real clinical benefit of the serial periodic determination of GM in the post allo-HCT period.

Material and methods: 139 consecutive patients who receivedan allo-HCT (59% related family member donorsand 41% unrelated donors) in our centre for five years (since January 2010 to February 2015) were included in the study. Median age was 46 years. Baseline characteristics of these patients are shown in figure 1. Patients were monitored with GM weekly and received primary prophylaxis with fluconazole since the admission until the immunosuppression was tapered.

In order to find a population that could benefit the most for AGA monitoring, we classified our population in low risk patients for invasive fungal infection (IFI) versus high risk patients (those with previous proven or probable IFI or those suffering from GVHD; high risk patients received anti-mold prophyllaxis, mainly with voriconazole or posaconazole). Patients considered as low risk who suffered from Graft versus Host Disease (GVHD) in the ulterior outcome, were censored for low risk and considered as high risk since the development of GVHD, and therefore anti-mold agent prophylaxis was started. GM positivity was determined according standard criteria. When GM positivity was detected, radiological and clinical studies (chest/sinus CT scans, cultures, etc.) to discard Aspegillosis were done as soon as possible. Every patient was followed up prospectively until the last medical consultation or decease.

Results: Global overall survival (OS) for the entire cohort was 55.39% and cumulative incidence for severe GVHD grade III/IV was 49.5%. During the follow up, GM became positive in 31/139 (22%) cases. With this approach, the global false positive and false negative rate was 31% and 6% respectively.110/139 (79.14%) patients were identificated as low risk cases. We observed GM positivization in 1.81% (2/110) and 37.18% (29/78) for low and high group respectively. All 2 positive GM in the low risk group were false positives. Regarding the high risk group, 34.48% (10/29) were false positives while in the rest 19 patients (65.52%), subsequent radiological and clinical findings allowed us to diagnose Aspergillus infection (besides they received anti-mold agent prophylaxis).

Conclusions: In our experience there is not enough evidence for supporting making serial monitoring with GM in low risk patients for IFI in the post allo-HCT period. However it may be an useful tool in high risk patients.