The delayed-type hypersensitivity response following administration of Spherusol ® was evaluated in one U.S. study which enrolled persons with a history of coccidioidomycosis. Two further U.S. studies enrolled subjects without a history of coccidioidomycosis; in one of these studies subjects had a history of histoplasmosis. In each study, concomitant with Spherusol ®, two additional skin test extracts, Candin ® and Trichophyton (positive controls), were administered along with a saline (negative control) and a diluent containing ≤ 0.0001% thimerosal (negative control). All skin tests and controls were administered as 0.1 mL doses in a randomized pattern on the volar surface of the forearms. Investigators and subjects were blinded to identity and placement of skin test antigens and controls. Responses were read at 48 hours (±4 hours) following administration. Induration responses were measured for each test site and recorded as the mean of the orthogonal diameters. A positive skin test was defined as a mean induration of ≥ 5 mm at 48 hours following administration of the antigens or controls. For each subject Spherusol ® skin test results were considered valid if ≥ 5 mm was observed at the positive control antigen sites and no induration ≥ 5 mm was observed at the negative control sites. 

The use of Spherusol ® to detect delayed-type hypersensitivity response in a general population with unknown exposure to C. immitis has not been evaluated. 

14.1 Induration Response in Subjects With a History of Pulmonary Coccidioidomycosis

A multicenter, double-blinded study in endemic areas (Bakersfield, CA and Tucson, AZ) enrolled 54 adults with a history of pulmonary coccidioidomycosis diagnosed by radiography, laboratory serologies (e.g., complement fixation, immunodiffusion) and/or culture. Subjects were 23-64 years of age; 28% women; 70% Caucasian, 11% Hispanic, 2% Asian, 2% Native American and 4% who did not specify race or ethnicity. Of the 51 subjects with valid skin test results, 50 subjects [98.0%; 2-sided 95% CI (89.6%, 100%)] had a mean induration of ≥ 5 mm at the Spherusol ® injection site. Among subjects with valid skin test results the average size of induration at the Spherusol ® injection site was 17 mm (range 5 mm-39 mm). 

The receipt of concurrent or previous antifungal therapy did not appear to interfere with or accentuate the induration response to Spherusol ®. 

14.2 Induration Response in Subjects Without a History of Pulmonary Coccidioidomycosis or Known Exposure to C. immitis.

A single site, double-blind study conducted in a non-endemic area for C. immitis (Spokane, WA) enrolled 60 adult subjects (18-56 years of age) with no known exposure to C. immitis by travel to or residency in an endemic area. Subjects had negative serologies to C. immitis by complement fixation, immunodiffusion and/or ELISA. Subjects enrolled in the study were 65% women; 96% Caucasian, 2% Hispanic and 2% Native American. At the 48 hour (± 4 hours) assessment, a total of 55 subjects had valid skin test results (5 subjects had negative skin test results to all reagents and were considered un-interpretable). One subject (1/55) had a 5 mm mean induration response to Spherusol ® and 54 subjects with demonstrated negative responses (< 5mm mean induration) to Spherusol ®. Fifty-four of the 55 subjects with valid skin test responses [98.2%; 2-sided 95% CI (90.3%, > 99.9%)] demonstrated a negative induration response to Spherusol ®. When the five subjects who had un-interpretable responses were analyzed as if these responses represented positive reactions to Spherusol ®, 54 of 60 subjects 90.0% (CI 79.5%, 96.2%) demonstrated a negative induration response. 

14.3 Induration Response in Subjects With a History of Pulmonary Histoplasmosis

A single site, double-blind study conducted in a non-endemic area for C. immitis, but endemic for H. capsulatum (Blair, NE) enrolled 12 adult subjects (33 to 60 years of age) with no known exposure to C. immitis by travel to or residency in an endemic area. All subjects had a history of pulmonary Histoplasmosis. Subjects had negative serologies to C. immitis by complement fixation, immunodiffusion and/or ELISA. Subjects were 42% women and 100% Caucasian. At the 48 hour (± 4 hours) assessment, all 12 subjects reacted to at least one of the positive controls with ≥ 5mm mean induration and demonstrated negative (< 5mm) induration responses to thimerosal and saline controls. No positive induration responses to Spherusol ® were observed [1-sided 97.5% CI; (0%, 26.5%)] among subjects who had a previous history of disease caused by H. capsulatum and no history of travel to areas endemic for C. immitis. These findings support the lack of cross-reaction between the cellular immune responses induced by the two fungal species.