INNOVATIVE TREATMENT OF SCARRED VOCAL FOLDS BY LOCAL INJECTION OF AUTOLOGOUS ADIPOSE-DERIVED STROMAL VASCULAR FRACTION: EFFICACY VERSUS PLACEBO

Vocal Folds scarring (whether congenitally or following phonosurgery) can result in a range of symptoms depending on severity and extent, such as hoarseness, breathy voice, increased effort to speak, and voice fatigue. The inability to phonate normally causes both physical and psychological disability, especially for professional communicators (teachers, tradesmen, singers, etc.). There are several therapies currently available but these are often disappointing, as the great complexity of vocal fold microstructure hinders the development of effective therapy. Thus, identification of innovative strategies able to improve vibrational mechanical properties of vocal folds remains an important clinical challenge.

Autologous Adipose-Derived Stromal Vascular Fraction (ADSVF) is recognized as an easily accessible source of cells displaying angiogenic, anti-inflammatory, immunomodulatory and regenerative properties. Recent experimental and clinical reports also supported the anti-fibrotic potential of ADVSF, mainly attributed to the mesenchymal stem/stromal cell subset.

Safety in humans has already been confirmed in several studies, including our previous clinical trial (ClinicalTrials.gov NCT0262246; EudraCT number: 2015-000238-31). The main objective of this phase I/II trial was to measure for the first time the safety and tolerability of autologous ADSVF local injections in patients with scarred vocal folds. No severe adverse events occurred: only some minor adverse events were reported. Moreover, Voice Handicap Index was improved in all patients with a mean improvement from baseline of 40.1/120 and seven patients were considered as responders, defined as an improvement ≥ 18 points.

Based on these observations, we hypothesized that the injection of autologous ADSVF could reduce the process of fibrosis, improve vibration and then dysphonia and quality of life in patients with scarred vocal folds.

In the absence of a reference treatment, the effectiveness of the ADSVF will be compared to a placebo: the local injection of excipients solution.

This study will test efficacy of the autologous ADSVF to treat vocal folds scarring. It is a randomized, double-blind, phase II clinical trial conducted according to a 2-treatment parallel design, with medico-surgical and scientific collaboration.

Recruitment and follow-up of patients will be done in 4 university hospitals by the respective ENT teams (Marseille, Toulouse, Nice and Montpellier): 36 patients will be recruited and treated on a 24 months period.

At inclusion, 36 patients will be randomized (1:1 ratio) into two groups: ADSVF group and placebo group. Adipose tissue removal, ADSVF production and injection of ADSVF or placebo will be done on the same day during a short hospital stay. Patients will be followed and evaluated at 1 and 6 months with self-evaluation (Voice Handicap Index and a 10 points scale), video-laryngo-stroboscopic examination, vocal assessment with perceptive, acoustic and aerodynamic parameters and evaluation of adverse events. At the end of this 6-month follow-up (primary endpoint), patients of each group having tolerated the first injection well but in therapeutic failure (improvement of VHI <18 as described by Jacobson in 1997 or improvement of VHI ≥ 18 but not normal which means > 20 according to Woisard, 2004) will be offered an injection of thawed and washed ADSVF. Patients will continue to be followed in open-label on the same endpoints.