SUN-357 Trial in Progress: A Multicenter, Dose-titration, Open-Label Phase 2b Study of Nevanimibe Hydrochloride, a Novel ACAT1 Inhibitor, for the Treatment of Classic Congenital Adrenal Hyperplasia

More than 90% of classic congenital adrenal hyperplasia (CAH) patients have defects in the cytochrome P450 enzyme steroid 21-hydroxylase, resulting in the inability to produce cortisol as well as the overproduction of androgens and androgen precursors such as 17-hydroxyprogesterone (17-OHP). Management of classic CAH can be challenging since patients are often unable to adequately balance the supraphysiologic doses of exogenous glucocorticoids required to suppress excess androgen production while avoiding the iatrogenic side effects of high dose glucocorticoids. Nevanimibe hydrochloride is a novel, orally-administered adrenal-specific acyl-CoA:cholesterol acyltransferase-1 (ACAT1) inhibitor. Nevanimibe inhibits adrenal steroidogenesis by decreasing cholesteryl esters, the substrate required for steroid synthesis. This inhibition of adrenocortical steroidogenesis at an early step results in impaired production across all pathways (i.e., mineralocorticoid, glucocorticoid and androgens). In a previous Phase 2 study in patients with classic CAH and elevated 17-OHP levels (NCT02804178), nevanimibe decreased 17-OHP levels within 2 weeks of treatment. Millendo Therapeutics is now conducting a Phase 2b study to evaluate the efficacy and safety of nevanimibe in treating patients with classic CAH over a longer period (NCT03669549). At approximately 12 sites in the EU, Israel, and Brazil, 20-24 patients with classic CAH and elevated 17-OHP will be treated with nevanimibe at doses of 1000-2000 mg twice per day for 12 weeks. During the screening period, patients who are on a high glucocorticoid dose and have suppressed 17-OHP levels may undergo a slight reduction in their supraphysiologic glucocorticoid dose in order to allow their 17-OHP levels to increase to > 4x the upper limit of normal (ULN). All eligible patients will be started on nevanimibe 1000 mg BID, and nevanimibe doses will be titrated based on 17-OHP levels. The primary efficacy endpoint is the proportion of patients who are able to achieve a reduction of 17-OHP to ≤ 2x ULN. Safety endpoints include the incidence of treatment-emergent adverse events (AEs) and serious adverse events (SAEs), as well as values and changes from baseline in clinical laboratory tests, vital signs, physical examinations, and electrocardiogram parameters. Nevanimibe, an adrenal-specific ACAT1 inhibitor, presents a novel therapeutic approach to the treatment of classic CAH that may allow patients to more easily achieve balance between replacement glucocorticoid doses and control of hyperandrogenemia.

Multisite reproducibility of results obtained by two broth dilution methods for susceptibility testing of Mycobacterium avium complex

A multicenter study was conducted to assess the interlaboratory reproducibility of susceptibility testing of Mycobacterium avium complex (MAC) by broth microdilution using two different media (cation-adjusted Mueller-Hinton broth with 5% oleic acid-albumin-dextrose-catalase and 7H9 broth with casein) and by macrodilution using the BACTEC 460TB and 12B media at pH 6.8 and 7.3 to 7.4. Ten well-characterized strains of MAC (four macrolide susceptible, six macrolide resistant) were tested against clarithromycin and azithromycin (the latter only by BACTEC 460TB, pH 6.8). At each site, strains were tested against clarithromycin three times on each of three separate days (nine testing events per isolate) by using a common lot of microdilution trays and BACTEC 12B medium, pH 6.8; strains were tested once on three separate days against clarithromycin in 12B medium at pH 7.3 to 7.4 and against azithromycin. Agreement among MICs (i.e., mode +/- 1 twofold dilution) was 100% for all strains and both drugs when BACTEC 460TB was used, regardless of the pH of the medium, but varied when microdilution with either medium was used, particularly with susceptible strains. Agreement based on interpretive category, with NCCLS-recommended breakpoints, was 100% for all strains with the BACTEC 460TB method (both drugs and both pH values) and with microdilution using 7H9 broth. With microdilution and Mueller-Hinton broth, agreement by interpretive category was 100% for eight isolates and >90% for two; errors occurred only in laboratories where personnel had minimal experience with this technique. MAC susceptibility testing may be performed by broth macrodilution or microdilution at either pH, with NCCLS-recommended interpretive breakpoints. However, because visual interpretation of broth microdilution end points is subjective, it is more prone to reader error; therefore, this method requires greater expertise than the BACTEC 460TB. Both techniques require appropriate validation and continued documentation of proficiency.

Multisite reproducibility of Etest for susceptibility testing of Mycobacterium abscessus, Mycobacterium chelonae, and Mycobacterium fortuitum

A multicenter study was conducted to assess the inter- and intralaboratory reproducibility of the Etest for susceptibility testing of the rapidly growing mycobacteria. The accuracy also was evaluated by comparing Etest results to those obtained by broth microdilution. Ten isolates (four of the Mycobacterium fortuitum group, three of Mycobacterium abscessus, and three of Mycobacterium chelonae) were tested against amikacin, cefoxitin, ciprofloxacin, clarithromycin, doxycycline, imipenem, and trimethoprim-sulfamethoxazole in each of four laboratories. At each site, isolates were tested three times on each of three separate days (nine testing events per isolate) using common lots of media and Etest strips. Interlaboratory agreement among MICs (i.e., mode +/- 1 twofold dilution) varied for the different drug-isolate combinations and overall was best for trimethoprim-sulfamethoxazole (75% for one isolate and 100% for all others), followed by doxycycline and ciprofloxacin. Interlaboratory agreement based on interpretive category also varied and overall was best for doxycycline (100% for all isolates), followed by trimethoprim-sulfamethoxazole and ciprofloxacin. Interlaboratory reproducibility among MICs was most variable for imipenem, and agreement by interpretive category was lowest for imipenem and amikacin. Modal Etest MICs agreed with those by broth microdilution only for doxycycline and the sulfonamides. For all other drugs, the modal MICs by the two methods differed by more than +/- 1 twofold dilution for one or more isolates. In all cases, the Etest MIC was higher and would have caused reports of false resistance. In summary, the Etest in this evaluation did not perform as well as broth microdilution for susceptibility testing of the rapidly growing mycobacteria. It was problematic for most species and drugs, primarily because of a trailing endpoint and/or high MICs compared to broth. Its use will necessitate further investigation, including determination of the optimal medium and incubation conditions and clarification of endpoint interpretation.

Multisite reproducibility of results obtained by the broth microdilution method for susceptibility testing of Mycobacterium abscessus, Mycobacterium chelonae, and Mycobacterium fortuitum

A multicenter study was conducted to assess the interlaboratory reproducibility of broth microdilution testing of the more common rapidly growing pathogenic mycobacteria. Ten isolates (four Mycobacterium fortuitum group, three Mycobacterium abscessus, and three Mycobacterium chelonae isolates) were tested against amikacin, cefoxitin, ciprofloxacin, clarithromycin, doxycycline, imipenem, sulfamethoxazole, and tobramycin (M. chelonae only) in four laboratories. At each site, isolates were tested three times on each of three separate days (nine testing events per isolate) with a common lot of microdilution trays. Agreement among MICs (i.e., mode +/- 1 twofold dilution) varied considerably for the different drug-isolate combinations and overall was best for cefoxitin (91.7 and 97.2% for one isolate each and 100% for all others), followed by doxycycline, amikacin, and ciprofloxacin. Agreement based on the interpretive category, using currently suggested breakpoints, also varied and overall was best for doxycycline (97.2% for one isolate and 100% for the rest), followed by ciprofloxacin and clarithromycin. Reproducibility among MICs and agreement by interpretive category was most variable for imipenem. Based on results reported from the individual sites, it appears that inexperience contributed significantly to the wide range of MICs of several drugs, especially clarithromycin, ciprofloxacin, and sulfamethoxazole. New interpretive guidelines are presented for the testing of M. fortuitum against clarithromycin; M. abscessus and M. chelonae against the aminoglycosides; and all three species against cefoxitin, doxycycline, and imipenem.

Clinical evaluation of difco ESP culture system II for growth and detection of mycobacteria

The reliability of the ESP Culture System II (ESP II; Difco Laboratories, Detroit, Mich.), a continuously monitoring mycobacterial culture system, was evaluated by comparing its performance with the BACTEC TB 460 (BACTEC TB) and Middlebrook 7H11/7H11 selective agar systems. A total of 2,283 specimens of all types (70.7% were respiratory specimens) were cultured; 149 (6.5%) yielded mycobacteria. The most common species recovered were Mycobacterium avium complex (MAC, 73 isolates) and Mycobacterium tuberculosis complex (MTBC, 53 isolates). The recovery rates by individual system were 87, 81, and 65% for ESP II, BACTEC TB, and Middlebrook agar, respectively, for all mycobacteria; the recovery rates were 89, 92, and 89%, respectively, for MTBC. For liquid plus solid medium system combinations, recovery rates for all mycobacteria and for MTBC, respectively, were 91 and 94% for ESP II plus Middlebrook agar and 85 and 96% for BACTEC TB plus Middlebrook agar. The difference between the recovery rates of all mycobacteria by ESP II and by BACTEC TB was not significant, whereas for the individual species, the only significant difference was recovery of more isolates of MAC by ESP II. For those isolates recovered in the individual systems, mean times to detection of all mycobacteria, MTBC, and MAC, respectively, were 13.1, 15.5, and 10.9 days for ESP II; 14.4, 16.6, and 12.1 days for BACTEC TB; and 17.8, 18.3, and 18.8 days for Middlebrook agar. ESP II is a reliable, nonradiometric, less labor-intensive alternative to BACTEC TB for growth and detection of mycobacteria, but as with other liquid culture methods, ESP II should be used in combination with a solid medium, not as a stand-alone system.

Cloning and sequence analysis of the major outer membrane protein gene of Chlamydia psittaci 6BC

The gene encoding the major outer membrane protein (MOMP) of the psittacine Chlamydia psittaci strain 6BC was cloned and sequenced. N-terminal protein sequencing of the mature MOMP indicated that it is posttranslationally processed at a site identical to the site previously identified in the MOMP of Chlamydia trachomatis L2. The nucleotide sequence of the C. psittaci 6BC MOMP gene was found to be 67 to 68% identical to those of human C. trachomatis strains, 73% identical to that of Chlamydia pneumoniae IOL-207, 79% identical to that of the C. psittaci guinea pig inclusion conjunctivitis strain, GPIC, and 83% identical to that of the C. psittaci ovine abortion strain S26/3. In contrast, the 6BC sequence was found to be greater than 99% identical to the sequences reported for two strains of C. psittaci, A22/M and Cal-10 meningopneumonitis, believed to be of nonpsittacine avian origin. Monoclonal antibody analysis confirmed the nonpsittacine avian origin of A22/M but identified the Cal-10 strain from which the MOMP gene was previously sequenced as a psittacine strain. These results confirm that psittacine and nonpsittacine avian strains of C. psittaci are closely related and distinct from the mammalian guinea pig inclusion conjunctivitis and ovine abortion strains of C. psittaci.