P-677 Increasing the efficacy of FSH with a potentiating monoclonal antibody
Authors: Kara E , Decourtye J , Casteret S , Dupuy L , Frydman R , Maurel M.C 
Published: June 2022

Abstract

Study question
Can we potentiate FSH activity with antibodies to improve ovarian stimulation?

Summary answer
IGYXOS developed a potentiating monoclonal antibody that improves FSH potency and efficacy in vitro and in vivo as demonstrated in different animal models.

What is known already
FSH plays a key role in reproduction. For a controlled ovarian stimulation in IVF cycles, FSH-containing preparations are injected to patients in order to obtain mature and fertilizable oocytes. However, the efficacy of these treatments is frequently limited and sometimes several attempts are needed before reaching a pregnancy and a live birth.
It was previously demonstrated that breeding animals treated with gonadotropins could develop anti-gonadotropin antibodies that enhance their bioactivity instead of inhibiting it. These females had a high kidding rate and sometimes were hyperprolific.

Study design, size, duration
IGYXOS developed a monoclonal antibody (mAb) directed against human FSH. The mAb CF12 was selected based on its ability to increase FSH activity in vitro and in vivo in female rat. Its potentiating activity was tested on different human FSH preparations. The potentiating effect of CF12 was further investigated in ewe treated with mAb alone or FSH alone.

Participants/materials, setting, methods
CF12 was tested in vitro on HEK 293 cells expressing the human FSH receptor and a cell reporter system for cAMP. In vivo, the mAb was tested according to the Steelman and Pohley protocol on different human FSH preparations. Its potentiating effect was also investigated in an ovulation induction protocol on mature ewes.

Main results and the role of chance
In HEK 293 cells expressing the human FSH receptor, CF12 combined to FSH improved both the potency (EC50) and the efficacy (Emax) of FSH by increasing the cyclic AMP production at all tested FSH concentrations. The potentiating activity was confirmed in immature female rats treated with hCG+FSH alone or combined to mAb, twice a day, during 3 days. The animals were sacrificed the fourth day of treatment and the weight of the ovaries was compared. Ovaries weight was significantly increased in the group treated with hCG/FSH+CF12 compared to hCG/FSH only.
To further analyze the effect of CF12 on ovulation induction, it was investigated in ewe as a breeding animal model. Animals were first synchronized with a progestagen and then treated either with FSH alone or with CF12 alone. The number of ovulations was investigated by endoscopy by counting corpora lutea and the progesterone secretion was measured over the luteal cycle. All females treated with CF12 ovulated (100%) by contrast 40% ovulated with FSH treatment. The ovulation rate was 1.8 fold higher in group treated with CF12 compared to FSH group. Moreover, progesterone secretion during luteal phase was increased in animals treated with CF12 suggesting a better quality of corpora lutea.

Limitations, reasons for caution
After several proofs of concept obtained in different animal models, the compound is currently in the humanization phase before starting the CMC process and then preclinical studies.

Wider implications of the findings
The potentiating antibody CF12 is a new concept. It represents an interesting strategy in reproductive health, particularly to improve the IVF outcome. CF12 is currently developed for human application by our company and could be a game changer in the field of ovarian stimulation by enhancing the efficacy of FSH.

Trial registration number
not applicable