Development of a Bio Medical Device (MD) for the prevention of the risk of pharyngeal fistula following total (pharyngo) laryngectomy – BIOFISS

The consortium includes a health care center, 2 complementary academic research laboratories specializing in biomaterials, 2 industrial partners including a MD manufacturer. This project is planned for a total duration of 48 months and is divided into 5 main scientific and technological work packages (WP).

WP1: Optimization of the biomaterial for the prevention of Salivary Fistula (CIRIMAT/RESCOLL, BROTHIER, INSERM) (M0-M18)

Task 1.1 Preparation of the absorbent layer of the biomaterial (M0-M8):

Task 1.2 Incorporation of an impermeable backing layer (M8-M18):

WP2: In vitro characterization of the biomaterial (INSERM, CIRIMAT) (M6-M36)

Task 2.1 Evaluation of in vitro biocompatibility and biodegradability

Task 2.2. Evaluation of wound healing properties of the biomaterial

Task 2.3. Evaluation of the antimicrobial properties of the biomaterial

WP3: In vivo trial (Institut Claudius Regaud/IUCTO) (M6-M48)

Task 3.1 Bioadhesion, biodegradation and biocompatibility tests on a rat pharyngotomy model and after sub-cutaneous implantation in mice (M12-M24)

Task 3.2 in vivo trial in mini pig model (M1-M48)

Task 3.2.1 Minipig neck irradiation model development (M1-M18)

Task 3.2.2 Porcine pharyngotomy model development (M1-M18)

Task 3.2.3 Biomaterial effectiveness, in vivo trial in minipigs (M24-M48)

WP4: Technology assessment, transfer and valorization (BROTHIER / all partners)

This paragraph summarizes the results of the main tasks of this project.

Task 1.1

Polyelectrolyte complexes (PECs) with alginate/chitosan mass ratios of 80/20 and 70/30 were produced and their properties were tested. The PECs with a mass ratio of 80/20 showed a higher swelling and degradation rate. All the PEC matrices obtained had satisfactory mechanical properties and were suturable.

Task 1.2

After developing the electrospinning process, a waterproof coating of poly DL-lactide-co-glycolide (PDLG) was incorporated into the absorbent matrix. Good adhesion between the two layers was achieved, as well as good hydrophobicity and impermeability.

Task 2.1

In vitro cytotoxicity assessment was performed according to ISO 10993. This showed better cytocompatibility for the Alg/Chi 80/20 ratio than for the 70/30 ratio. Sterilization by electron beam irradiation at a dose of 25 kGy at -20°C produces a cytocompatible biomaterial.

Task 3.1

Tolerance (biocompatibility), bioresorption, and bioadhesion tests were then conducted on 10 mice, after implanting a DM patch in each flank, and on 29 rats after cervical implantation following pharyngotomy. This confirmed that the biocompatibility of DM appeared acceptable. However, there were cases of scar separation with possible clinical infection of undetermined cause. The inflammatory reaction around the DM fragments remained significant, even at D30, with incomplete resorption of the DM. The measurement of a panel of cytokines did not reveal any marked increase in inflammation markers between the preoperative period (t0) and euthanasia (t1).

Task 3.2.3

Finally, an efficacy trial was conducted in 30 minipigs. Half of the minipigs received a single pharyngolaryngeal irradiation (17Gy) one month before surgery. The surgery consisted of a posterior pharyngectomy with pharyngeal suturing (a risk factor for fistula, particularly in irradiated areas) and application of the DM (n = 20) or no DM (n = 10) according to a randomization performed intraoperatively after pharyngeal suturing.

The animals were euthanized at 1 month, or earlier if there were signs of fistula or damage to the endpoints. A total of 7 fistulas occurred, with no difference between the DM group and the control group (25% vs. 20%, respectively). They manifested as weight loss and deterioration in general condition and were confirmed by macroscopic and microscopic examination of the explant. The fistula rate was slightly lower in the DM group in the absence of irradiation (0% vs. 20%), but higher in the DM group in cases of prior irradiation (50% vs. 20%). There was a statistical trend toward an increased risk of fistula in irradiated vs. non-irradiated areas (p=0.08).

We have succeeded in modulating the mechanical and physicochemical properties (absorption, resorption, cytotoxicity) of this innovatively designed medical device to meet the specifications, and in maintaining them after sterilization. However, the medical device does not appear to have demonstrated sufficient efficacy to justify clinical trials in humans at this stage. Unfortunately, the results of our efficacy trial are negative in irradiated areas. However, it is in these areas that the highest number of fistulas occur and where the clinical and medico-economic interest is greatest.

The clinical need remains strong, and the development of such a DM therefore remains a goal for our team, based on the results of this study. Several avenues for improvement remain under discussion, both in terms of the DM and the design of animal experiments:

- Improving the bioadhesion of the DM;

- Improving the impermeability of the hydrophobic coating;

- Adding a bioactive, antioxidant, or anti-inflammatory property to optimize its functioning in irradiated areas, or a pro-healing property via the release of growth factors (however, not recommended in this oncological context);

- Use another animal model with pharyngo-esophageal section and anastomosis, or improve the method of DM application;

- Increase the number of animals included.

This ambitious project, which includes trials in irradiated terrain, highlights the difficulties caused by irradiation, which alters cellular and tissue pathophysiology and therefore the metabolism and functioning of any biomaterial. This project will thus have made it possible to deepen knowledge of the physiology of biomaterials in irradiated terrain, the modulation of the properties of alginate- and chitosan-based biomaterials, and to develop the only model of pharyngeal fistula in large animals.

Translated with DeepL.com (free version)

in process

Background :
Head and Neck cancers are common, 4th ranking in terms of incidence. Total (pharyngo) laryngectomy (T(P)L) is a common surgery for the treatment of pharyngo-laryngeal cancers and results in the definitive separation of the respiratory and digestive (neo-pharyngeal) tracts. The main issue with this surgery is salivary fistula (SF) (incidence of 20 to 65%), causing leaks of saliva between the sutures of the neo-pharynx. One of the main risk factors is a history of irradiation. Saliva, by flowing into the neck, causes high morbidity i.e. increased length of hospitalization, surgical revision, risk of vascular rupture and death i.e. incidence of carotid blowout syndrome around 3%. There is no current solution to reduce the incidence of SF.
Objectives and means:
The BIOFISS project aims to develop an innovative biomaterial (MD) in the form of a double-layer film based on biopolymers, alginate and chitosan, for the prevention of SF. The project brings together a suitable consortium with a hospital specialized in oncology (IUCT-O), 2 academic research laboratories specialized in biomaterials (CIRIMAT and INSERM UMR 1121) and 2 industrial partners (RESCOLL and Brothier) including a MD manufacturer specialized in alginate, one of the constituents of the MD.
This project is based on preliminary results concerning the design of alginate-based biomaterials (CIRIMAT laboratory).
The 4 main objectives of the BIOFISS project are 1) development of MD to obtain the physico-chemical and biological properties suitable for the prevention of SF; 2) characterization of its in vitro properties (biocompatibility, mechanical properties, bioadhesion, degradation time); 3) in vivo evaluation; 4) transfer and valorization
Materials and Methods:
This project is planned over a total of 48 months and is divided into 5 scientific axes (WP):
1. WP0: project coordination (IUCT-O/all partners)
2. WP1: Optimization of MD for SF prevention with 2 tasks: 1) development of the impermeable layer; 2) development of the absorbent layer. This axis will be coordinated by CIRIMAT using the technologies of RESCOLL and INSERM UMR 1121. Brothier will provide the alginate and will contribute its knowledge on these materials.
3. WP2: in vitro characterization of the physicochemical properties of MD; this axis will be coordinated by INSERM 1121 in collaboration with CIRIMAT. 3 tasks will be carried out: 1) evaluation of biocompatibility; 2) evaluation of healing properties; 3) evaluation of antimicrobial properties.
4. WP 3: in vivo evaluation (IUCT-O) with 4 tasks: 1) evaluation of biocompatibility and bioadhesion in a rat pharyngotomy model; 2) development of an irradiated mini-pig model; 3) development of a laryngectomized mini-pig model; 4) evaluation of the efficacy of MD on laryngectomized pigs with or without irradiation with a control group.
5. WP4: Evaluation of results, transfer and valorisation of technologies (Brothier laboratory)
Expected results:
In accordance with the ANR Call for Proposals, the goal of our project is to design an innovative MD aimed to reduce the rate of SF in T(P)L patients undergoing T(P)L surgery. Based on a strong consortium, all data collected during the project will provide evidence of the efficacy and safety of the new MD for the initiation of a clinical trial in the prevention of the risk of SF after neck surgery.
The field of use of the biomaterial could be wider than the T(P)L, i.e. useful for many cervico-facial surgeries (cancer or not) or even in digestive surgery.
BIOFISS will make it possible to perpetuate the collaboration between industrial partners for the commercialization of this new biomaterial. A new production line, which will require the recruitment of qualified personnel, will be created within Brothier for the manufacture of this new MD.