Jemily Malvar

Supplementary Fig. 2 Cumulative incidence of SIOP Grade ≥2 hearing loss

Supplementary Fig. 5 Progression-free survival in NAC treated and observation patients

Supplementary Fig. 4 Evaluation of long-term storage of serum specimens (NAC assay)

Supplementary Fig. 1 Treatment schema & Sampling Timepoints

Supplementary Fig. 3 Change in serum glutathione concentrations following NAC infusion

Purpose:Cisplatin-induced hearing loss (CIHL) is common and permanent. As compared with earlier otoprotectants, we hypothesized N-acetylcysteine (NAC) offers potential for stronger otoprotection through stimulation of glutathione (GSH) production. This study tested the optimal dose, safety, and efficacy of NAC to prevent CIHL.Patients and Methods:In this nonrandomized, controlled phase Ia/Ib trial, children and adolescents newly diagnosed with nonmetastatic, cisplatin-treated tumors received NAC intravenously 4 hours post-cisplatin. The trial performed dose-escalation across three dose levels to establish a safe dose that exceeded the targeted peak serum NAC concentration of 1.5 mmol/L (as identified from preclinical models). Patients with metastatic disease or who were otherwise ineligible were enrolled in an observation-only/control arm. To evaluate efficacy, serial age-appropriate audiology assessments were performed. Integrated biology examined genes involved in GSH metabolism and post-NAC GSH concentrations.Results:Of 52 patients enrolled, 24 received NAC and 28 were in the control arm. The maximum tolerated dose was not reached; analysis of peak NAC concentration identified 450 mg/kg as the recommended phase II dose (RP2D). Infusion-related reactions were common. No severe adverse events occurred. Compared with the control arm, NAC decreased likelihood of CIHL at the end of cisplatin therapy [OR, 0.13; 95% confidence interval (CI), 0.021–0.847; P = 0.033] and recommendations for hearing intervention at end of study (OR, 0.082; 95% CI, 0.011–0.60; P = 0.014). NAC increased GSH; GSTP1 influenced risk for CIHL and NAC otoprotection.Conclusions:NAC was safe at the RP2D, with strong evidence for efficacy to prevent CIHL, warranting further development as a next-generation otoprotectant.

Supplementary Fig. 4 Evaluation of long-term storage of serum specimens (NAC assay)

Supplementary Fig. 5 Progression-free survival in NAC treated and observation patients

Supplementary Fig. 2 Cumulative incidence of SIOP Grade ≥2 hearing loss