[Antifungal susceptibility of clinically isolated invasive Candida tropicalis in East China from 2017 to 2021]

Objective: To explore the epidemiological characteristics of sample distribution and antifungal susceptibilities of clinically invasive C. tropicalis isolates from 2017 to 2021 in East China. Methods: Using a retrospective analysis, the East China Invasive Fungal Infection Group (ECIFIG) collected C. tropicalis clinically isolated from 32 hospitals in East China between January 2017 and December 2021. The identification results of the strains were reviewed using mass spectrometry by the central laboratory of the Shanghai East Hospital. The minimum inhibitory concentrations (MICs) of the strains against fluconazole (FLU), voriconazole (VOR), itraconazole (ITR), Posaconazole (POS), isavuconazole (ISA), anidulafungin (ANI), caspofungin (CAS), micafungin (MICA) and 5-fluorocytosine (FCT) were tested by the ThermoFisher CMC1JHY colorimetric microdilution method. The MIC of amphotericin B (AMB) was tested by the broth microdilution method. The MIC results were analyzed based on the clinical breakpoints and epidemiological cutoff values (ECV) published by the Clinical and Laboratory Standards Institute (CLSI) M27 Ed3 and M57 Ed4 documents. Data analysis was conducted using the Kruskal-Wallis test and paired t-test. Results: In total, 305 C. tropicalis isolates were collected. There were 38.0% (116/305) strains isolated from blood, 11.5% (35/305) ascites, 8.9% (27/305) catheter and 8.9% (27/305) drainage fluid. The resistance rate of C. tropicalis to FLU was 32.5%, to VOR was 28.5%, and the cross-resistance rate to FLU and VOR was 28.5%. The wild-type proportions for ITR and POS were 79.3% and 29.2% respectively. There was no significant difference in resistance rates, MIC50, and MIC90 of FLU and VOR, or in the wild-type rates of ITR and POS over five years. More than 95.0% of the isolates were susceptible to echinocandins. However, one strain was identified as being multi-drug resistant. In azole antifungals, voriconazole, itraconazole, posaconazole, and isavuconazole have similar GM MIC values. The GM MIC of fluconazole is significantly higher than that of itraconazole (t=9.95, P<0.05), posaconazole (t=9.99, P<0.05), and voriconazole (t=10.01, P<0.05), Meanwhile, among echinocandins, the GM MIC of ANI was comparable to that of CAS (t=1.17, P>0.05), both of which were significantly higher than MICA (t=11.56, P<0.05; t=4.15, P<0.05). Conclusion: The clinical isolates of C. tropicalis in East China from 2017 to 2021 were relatively susceptible to echinocandins. However, there was consistently high resistance to fluconazole and voriconazole. More intensive efforts should be made on the monitoring of drug resistance in C. tropicalis.

Gefitinib for advanced cutaneous squamous cell carcinoma of head and neck: Phase II trial

6054

Background: Advanced head and neck cutaneous squamous cell carcinoma (HN cSCC) carries a 30–40% risk of death by 2 years with standard therapies. Small molecular inhibitors of the epidermal growth factor receptor (EGFR) may have an impact. We evaluated gefitinib as an induction therapy in a high-risk patient (pt) group prior to definitive therapy to determine efficacy, toxicity and feasibility. Correlative studies of EGFR expression, gene mutation, and ploidy may serve as predictors of response. Methods: Eligible pts must have HN cSCC >2cm, regional nodal metastases, peri-neural invasion, or deep invasion and must be candidates for definitive locoregional therapy with surgery and/or radiation. Two 30-day induction cycles of gefitinib (250mg po qd). Pts are assessed clinically after 15 days. If a response is noted, gefitinib is continued. For pts with stable disease, the dose is escalated to 500mg qd. Pts with progressive disease go off study. Total and phosphorylated (p) EGFR protein expression was analyzed by immunohistochemistry and gene copy number by fluorescent in-situ hybridization (FISH). Results: To date, 23 pts are enrolled and 22 are evaluable for responses and toxicities. Complete responses (CR) were noted in 3 pts, partial response (PR) 7, stable disease (SD) 5, and progressive disease (PD) 7 (68.1% response per RECIST criteria). Minimal side effects are associated with gefitinib (cutaneous and GI related). EGFR and p-EGFR protein overexpression were observed in 5 of 11 (45.5%) pts tested thus far. Eight of the pts were FISH negative with respect to EGFR gene expression: 7 had low trisomy and 1 had low polysomy. Two were FISH positive and expressed high polysomy. No gene amplification was detected. No statistically significant correlations between EGFR gene or protein expression and responses to administration of gefitinib were found at this point in the analysis. Protein and gene expression analyses are ongoing. Conclusions: The preliminary results from our study are encouraging and suggest that anti-EGFR therapy may have a role in the adjuvant treatment of HN cSCC. Correlative studies may help identify pts most likely to respond to anti-EGFR therapy.

No significant financial relationships to disclose.