Nuove Tecniche di Stimolazione dell’Ovulazione Multipla · Controlled ovarian stimulation Goals to induce multiple folliculogenesis in patients candidate for assisted reproduction

Nuove Tecniche di Stimolazione Nuove Tecniche di Stimolazione

dell’Ovulazione Multipladell’Ovulazione Multipla

Prof. Marco FILICORIProf. Marco FILICORIGynePro RiproduzioneGynePro Riproduzione

Centri Medici GyneProCentri Medici GynePro

BOLOGNABOLOGNA

Controlled ovarian stimulationControlled ovarian stimulation

GoalsGoals�� to induce multiple folliculogenesis in to induce multiple folliculogenesis in

patients candidate for assisted patients candidate for assisted reproduction procedures to increase reproduction procedures to increase oocyte yield at retrievaloocyte yield at retrieval

�� limit risks of excessive ovarian limit risks of excessive ovarian stimulation (ovarian hyperstimulation)stimulation (ovarian hyperstimulation)

ProcedureProcedure�� use a combination of use a combination of

�� exogenous gonadotropins (recombinant or exogenous gonadotropins (recombinant or humanhuman--derived)derived)

�� GnRH analogs (agonists or antagonists) GnRH analogs (agonists or antagonists)

�� to achieve this goal, while avoiding to achieve this goal, while avoiding spontaneous ovulationspontaneous ovulation

Regimens for controlled ovarian stimulationRegimens for controlled ovarian stimulation

hCG/LHhCG/LHday day --77 day +2day +2 day +6day +6

menstrual menstrual cycle daycycle day

FSH/hMGFSH/hMG

GnRH agonistGnRH agonist

FSH/hMGFSH/hMG

GnRH antagonistGnRH antagonist

Novel controlled ovarian stimulation regimensNovel controlled ovarian stimulation regimens

�� use of GnRH agonists to use of GnRH agonists to

trigger ovulationtrigger ovulation

�� reassessment of FSH reassessment of FSH

structurestructure

�� new gonadotropin new gonadotropin

formulationsformulations

�� novel regimens with LH novel regimens with LH

activityactivity

receptoractivation

receptoraffinity

biologicactivity

GnRH GnRH agonistsagonistspyrpyrpyr hishis trptrp serser tyrtyr leuleu argarg propro

GnRHGnRHantagonistsantagonists

serser leuleu propro

GnRHGnRHpyrpyrpyr hishis trptrp serser tyrtyr glygly leuleu argarg propro glygly

StructureStructure--related activity of GnRH and analogsrelated activity of GnRH and analogs

MECHANISMS OF GnRH AGONIST ACTION

�� GnRH receptor internalization GnRH receptor internalization

and postand post--receptor block of receptor block of

gonadotropin synthesisgonadotropin synthesis

�� non competitivenon competitive processprocess

�� late pituitary suppressionlate pituitary suppression

(1(1--2 weeks)2 weeks)

GnRH agonists structure: GnRH agonists structure:

aminoacid sequence substitutionsaminoacid sequence substitutions

66 77 1010

DD--LeuLeu -- NEtNEt

NEtNEt

NEtNEt

NEtNEt

NEtNEt

DD--TrpTrp

--

--

--

--

--

--

DD--TrpTrp

DD--TrpTrp NN--MeMe--LeuLeu

DD--Ser(tBU)Ser(tBU)

DD--Ser(tBU)Ser(tBU) azaaza--GlyGly

DD--His(Bzl)His(Bzl)

DD--Ala(2Ala(2--Naph)Naph) -- --

namename CompanyCompany

leuprorelinleuprorelin(Enantone)(Enantone)

Takeda, TAPTakeda, TAP

triptorelintriptorelin(Decapeptyl)(Decapeptyl)

Ferring, IPSEN Ferring, IPSEN

deslorelindeslorelin Salk InstituteSalk Institute

lutrelinlutrelin WyethWyeth

buserelinbuserelin((SuprefactSuprefact))

HoechstHoechst

goserelingoserelin((ZoladexZoladex))

AstraZenecaAstraZeneca

histrelinhistrelin Ortho, RobertsOrtho, Roberts

nafarelinnafarelin SyntexSyntex

�� competitivecompetitive pituitary pituitary

GnRH receptor blockGnRH receptor block

�� immediate pituitary immediate pituitary

suppressionsuppression

MECHANISMS OF GnRH ANTAGONIST ACTION

33rdrd generation GnRH antagonists structure: generation GnRH antagonists structure:

aminoacid sequence substitutionsaminoacid sequence substitutions

11 22 33

DD--NicNic

LysLys

namename

AntideAntide(Serono)(Serono)

Azaline BAzaline B

AA--7599875998

GanirelixGanirelix(Organon)(Organon)

CetrorelixCetrorelix(ASTA (ASTA -- Serono)Serono)

55 66 1010

DD--PalPal NicNic

LysLys

-- DD--hArghArg DD--AlaAla

IprIpr

LysLys

88

LL--hArghArg

AcDAcD

--NalNalDD--4Cl4Cl

PhePheDD--AlaAla

DD--AphAph

(atz)(atz)DD--PalPal AphAph

(atz)(atz)IprIpr

LysLysAcDAcD

--NalNalDD--4Cl4Cl

PhePheDD--AlaAla

DD--PalPal NN--MeMe

TyrTyrIprIpr

LysLysAcDAcD

--NalNalDD--4Cl4Cl

PhePheDD--AlaAlaDD--NicNic

LysLys

DD--PalPalAcDAcD

--NalNalDD--4Cl4Cl

PhePhe

-- DD--CitCit DD--AlaAla--DD--PalPalAcDAcD

--NalNalDD--4Cl4Cl

PhePhe

Regimens for controlled ovarian stimulationRegimens for controlled ovarian stimulation

GnRHGnRH--aaday day --77 day +2day +2 day +6day +6

menstrual menstrual cycle daycycle day

FSH/hMGFSH/hMG

GnRH antagonistGnRH antagonist

GnRH and GnRH agonist regimens employed to GnRH and GnRH agonist regimens employed to


11--55

11

11

11

11

11

11--22

11

22

11--22

timestimes

i.n.i.n.4h4h2525--100100buserelinbuserelinBuckettBuckett, 98, 98

s.c.s.c.--200200triptorelintriptorelinLewitLewit, 96, 96

i.v.i.v.--100, 500100, 500buserelinbuserelin, GnRH, GnRHGerrisGerris, 95, 95

i.v.i.v.--200200GnRHGnRHBlumenfeldBlumenfeld, 94, 94

s.c.s.c.--500500--1,0001,000leuprorelinleuprorelinBalaschBalasch, 94, 94

s.c.s.c.--200200buserelinbuserelinLanzoneLanzone, 94, 94

i.n.i.n.12h12h400400nafarelinnafarelinCorson, 93Corson, 93

s.c.s.c.--500500leuprorelinleuprorelinSegal, 92Segal, 92

s.c.s.c.16h16h500500leuprorelinleuprorelinTulchinskyTulchinsky, 91, 91

s.c.s.c.12h12h250250--500500buserelinbuserelinIskowitzIskowitz, 91, 91

routerouteintervalintervaldose (µg)dose (µg)GnRH/GnRH/GnRHaGnRHa

GnRH agonist to trigger ovulation in GnRH agonist to trigger ovulation in

GnRH antagonist cyclesGnRH antagonist cycles

comparable fertilization, comparable fertilization,

lower pregnancy ratelower pregnancy rate

comparable fertilization, comparable fertilization,

lowerlower implantation & implantation &

pregnancy ratepregnancy rate

no OHSSno OHSS

comparablecomparable oocyte number, oocyte number,

fertilization, implantation & fertilization, implantation &


comparablecomparable oocyte number, oocyte number,

fertilization, implantation & fertilization, implantation &


outcomeoutcome

metameta--

analysisanalysisGriesinger et alGriesinger et al

Hum Reprod UpdateHum Reprod Update

12:327, 200612:327, 2006

retrospectiveretrospectiveOrvietoOrvieto et alet al

RBM OnlineRBM Online

13:639, 200613:639, 2006

oocyte oocyte

donorsdonorsAcevedo et alAcevedo et al

Fertil SterilFertil Steril

86:1682, 200686:1682, 2006

PCOS & high PCOS & high

respondersrespondersEngmannEngmann et alet al

RBM Online, 2006RBM Online, 2006

Fertil Steril, 2008Fertil Steril, 2008

studystudyauthorsauthors

Use of GnRH agonists to trigger ovulation in COSUse of GnRH agonists to trigger ovulation in COS

�� GnRH agonist use appears to be GnRH agonist use appears to be

associated with a reduced occurrence associated with a reduced occurrence

of OHSS than hCG in atof OHSS than hCG in at--risk patientsrisk patients

�� luteal phase supplementation with luteal phase supplementation with

progesterone (and possibly estradiol) progesterone (and possibly estradiol)

may be critical to ensure optimal may be critical to ensure optimal

implantation and pregnancy ratesimplantation and pregnancy rates





structurestructure




activityactivity

Composition of gonadotropin subunitsComposition of gonadotropin subunits

6 6 (2 (2 asparagineasparagine--linked, 4 serinelinked, 4 serine--linked)linked)

145145CG CG ββββββββ

2 2 ((asparagineasparagine--linked)linked)

117117FSH FSH ββββββββ


121121LH LH ββββββββ


9292αααααααα

carbohydrate groupscarbohydrate groupsAAAAsubunit subunit

typetype

ASNASN

N-Acetyl-Glucosamine

Mannose

Galactose

Sialic Acid

FSH – A complex molecule

Oligosaccharide chain structure

Gonadotropin isoformsGonadotropin isoforms

�� gonadotropin isoforms differ in glycosylation pattern gonadotropin isoforms differ in glycosylation pattern complexity and number of sialic acid residuescomplexity and number of sialic acid residues�� LHLH has 6has 6--9 isoforms 9 isoforms

�� FSHFSH has 20 isoforms has 20 isoforms

�� hCGhCG has 20+ isoformshas 20+ isoforms

�� less acidic FSH isoforms less acidic FSH isoforms (recombinant FSH)(recombinant FSH)�� prevail in the preovulatory phaseprevail in the preovulatory phase

�� have the highest biologic activity in have the highest biologic activity in inin--vitrovitro bioassaysbioassays

�� are rapidly cleared from the circulationare rapidly cleared from the circulation

�� more acidic FSH isoforms more acidic FSH isoforms (human(human--derived FSH)derived FSH)�� prevail in the early follicular phase and menopauseprevail in the early follicular phase and menopause

�� less active in less active in inin--vitrovitro bioassaysbioassays

�� present in higher concentrations in the circulationpresent in higher concentrations in the circulation

�� more active more active inin--vivovivo

Fostimon (IBSA)IBSA data on file

Bravelle (Ferring)Wolfenson 05

Gonal F (Serono)Driebergen 03

Puregon (Organon)De Leeuw 96

0-sialic 1-sialic 2-sialic 3-sialic 4-sialic

13

5 36 41 16

57

43 33 9 2

2

2 36<5 <5

8 30 47 12 3

oligosaccharide composition (%)

FSH Glycosylation

LH

(IU

/L)

0

1

2

3

4

FS

H (

IU/L

)

0

2

4

6

8

10

12

rFSHαααα

HP hMG

days of treatment

0 2 4 6 8 10

hC

G (

IU/L

)

0.0

0.5

1.0

LHLH(IU/L)(IU/L)

FSHFSH(IU/L)(IU/L)

hCGhCG(IU/L)(IU/L)

P NSP NS

P<0.001P<0.001

P<0.001P<0.001

HP hMG vs. rFSH HP hMG vs. rFSH -- Gonadotropin serum levelsGonadotropin serum levels(Kilani et al, Hum Reprod, 18:1194, 2003)(Kilani et al, Hum Reprod, 18:1194, 2003)

Pharmacological and clinical Pharmacological and clinical implications of implications of

FSH isoforms FSH isoforms -- summarysummary

�� glycosylation and acidity patterns of FSH vary glycosylation and acidity patterns of FSH vary

across the menstrual cycle and life stagesacross the menstrual cycle and life stages

�� humanhuman--derived FSH has a more complex derived FSH has a more complex

glycosylation pattern and contains greater glycosylation pattern and contains greater

amounts of sialic acid than recombinant FSHamounts of sialic acid than recombinant FSH

�� structural features of different FSH preparations structural features of different FSH preparations

may have relevant clinical implicationsmay have relevant clinical implications





structurestructure




activityactivity

LongLong--acting acting corifollitropincorifollitropin alphaalpha

Corifollitropin alpha is a novel recombinant gonadotropin molecule, in

which the FSH-ββββ chain is fused with the carboxy-terminal peptide of the

hCG-ββββ subunit

Corifollitropin alpha is a new class of drugs with the proposed drug class name Sustained Follicle Stimulants (SFS)

Chimeric longChimeric long--acting recombinant FSH agonist with a acting recombinant FSH agonist with a

carboxy terminal peptide (FSH CTP) �carboxy terminal peptide (FSH CTP) �

FSH CTP hasFSH CTP has

�� an FSH an FSH αααααααα--subunit identical to hFSHsubunit identical to hFSH

�� a hybrid FSH a hybrid FSH ββββββββ--subunit composed ofsubunit composed of�� an initial aminoacid sequence identical to an initial aminoacid sequence identical to

hFSHhFSH

�� a carboxy terminal peptide (CTP) complex a carboxy terminal peptide (CTP) complex

similar to the hCG similar to the hCG ββββββββ--subunitsubunit

Ala

Asn

Ser

Asn

Ser

Asn

Asn

Ser

CH/S

CH/S

CH/S

CH/S

α β

CH/S

CH/SCH/S

CH/S

Ser

Ser

Ser

Ser

Glu

Amino acid (AA) sequence:Amino acid (AA) sequence:Amino acid (AA) sequence:Amino acid (AA) sequence:

• No deviation from human sequence

• No additional linkage AA

Carbohydrate side chains:Carbohydrate side chains:Carbohydrate side chains:Carbohydrate side chains:

• 4 N-linked similar to FSH

• 4 O-linked similar to hCG

Molecular structure of corifollitropin alfa

92 AA

111 AA+

28 AA

FSH CTP and rFSH pharmacokinetics in Beagle dogsFSH CTP and rFSH pharmacokinetics in Beagle dogs

0000 50505050 100100100100 150150150150 200200200200 250250250250

Hours after injectionHours after injectionHours after injectionHours after injection

0.0010.0010.0010.001

0.010.010.010.01

0.10.10.10.1

1111

2222

FSH

FSH

FSH

FSH

im

muno

imm

uno

imm

uno

imm

uno-- --ac

tivi

ty (

activi

ty (

activi

ty (

activi

ty (

Del

fia

Del

fia

Del

fia

Del

fia

IU/l)

IU/l)

IU/l)

IU/l)

Org 36286 Org 36286 Org 36286 Org 36286 i.vi.vi.vi.v....Org 36286 Org 36286 Org 36286 Org 36286 i.mi.mi.mi.m....

Puregon/Puregon/Puregon/Puregon/FollistimFollistimFollistimFollistim i.mi.mi.mi.m....

Characteristics of FSH CTPCharacteristics of FSH CTP

�� features features DevroeyDevroey et al, JCE&M 86:2062, 2004 (120, 180, 240 µg)et al, JCE&M 86:2062, 2004 (120, 180, 240 µg)

�� FSH levels peak at 46hFSH levels peak at 46h

�� terminal FSH halfterminal FSH half--life in women 65hlife in women 65h

�� prospros�� can be administered at 7can be administered at 7--day intervals (1st week of ovarian day intervals (1st week of ovarian

stimulation)stimulation)

�� more oocytes? (240 µg dose)more oocytes? (240 µg dose)

�� conscons�� higher incidence of premature ovulation (antagonist tailored higher incidence of premature ovulation (antagonist tailored

regimen)regimen)

�� lesser stimulation controllesser stimulation control

First live birth obtained using FSH CTPFirst live birth obtained using FSH CTP

Beckers et al, Fertil Beckers et al, Fertil Steril 79:621, 2003Steril 79:621, 2003





structurestructure




activityactivity

FSHFSH

follicular phasefollicular phase

earlyearly midmid latelate

exogenous

exogenous

gonadotropin dose

gonadotropin dose

LHLH

hCGhCG

rLHrLH

Traditional ovarian stimulation regimensTraditional ovarian stimulation regimens

ACTIONS OF LH/hCGACTIONS OF LH/hCG�� preantral and small antral preantral and small antral

follicles (<10follicles (<10--12 mm)12 mm)�� stimulation of stimulation of theca celltheca cell androgen androgen

productionproduction

�� large antral follicles large antral follicles (>10(>10--12 mm)12 mm)

�� stimulation of stimulation of theca celltheca cellandrogen productionandrogen production

FSHFSH--like actionslike actions�� stimulation of stimulation of granulosa granulosa

cellcell proliferation and proliferation and growthgrowth

�� induction of induction of granulosa cellgranulosa cellaromatase to catalyze aromatase to catalyze estrogen formationestrogen formation

FSH/hMGFSH/hMG

follicular phasefollicular phase

earlyearly midmid latelate

exogenous

exogenous

gonadotropin dose

gonadotropin dose

LH/hCGLH/hCG

hCGhCG

rr--hLHhLH

Proposed ovarian stimulation regimenProposed ovarian stimulation regimenFilicori and Cognigni, JCE&M, 86:1437, 2001Filicori and Cognigni, JCE&M, 86:1437, 2001

Protocol schemeProtocol schemeFilicori et al, Fertil Steril 84:394, 2005Filicori et al, Fertil Steril 84:394, 2005

hCG10,000 IU

depot triptorelin 3.75 mgdepot triptorelin 3.75 mg

group A group A (24 pts)(24 pts) �� rFSH/hMG

OP

U

ICS

I

hCG 200 IU/dayhCG 200 IU/daygroup B group B (24 pts)(24 pts) �� rFSH/hMG

> 6 follicles > 12mmand

E2 > 600 pg/mL

OP

U

ICS

I

E2 (

pg

/mL

)

0

1000

2000

3000

4000

A - rFSH/hMG alone

B - rFSH/hMG & hCG

P (

ng

/mL

)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Days of treatment

0 2 4 6 8 10 12

T (

ng

/mL

)

0.0

0.5

1.0

1.5

2.0

LH

(IU

/L)

0

1

2

3

4

A - rFSH/hMG alone

B - rFSH/hMG & hCG

FS

H (

IU/L

)

0

2

4

6

8

10

12

14

16

Days of treatment

0 2 4 6 8 10 12

hC

G (

IU/L

)

0

2

4

6

8

10

Filicori et al, Fertil Steril 84:394, 2005

Daily serum hormone Daily serum hormone

levels centered upon levels centered upon

rFSH/hMG rFSH/hMG

discontinuation and discontinuation and

lowlow--dose hCG dose hCG

initiationinitiation-10 -8 -6 -4 -2 0 2 4

LH

(IU

/L)

0

1

2

3

4

-10 -8 -6 -4 -2 0 2 4

FS

H (

IU/L

)

2

4

6

8

10

12

14

16

Days to/from hCG start

-10 -8 -6 -4 -2 0 2 4

hC

G (

IU/L

)

0

2

4

6

8

10

12

-10 -8 -6 -4 -2 0 2 4

E2

(p

g/m

L)

0

1000

2000

3000

4000

5000

-10 -8 -6 -4 -2 0 2 4

P (

ng

/mL

)

0,0

0,5

1,0

1,5

2,0

Days to/from hCG start

-10 -8 -6 -4 -2 0 2 4

T (

ng

/mL

)

0,0

0,4

0,8

1,2

1,6

hMG

rFSH

low-dose hCGstarted

Ovarian follicle pattern Ovarian follicle pattern

during lowduring low--dose hCG dose hCG

treatmenttreatment

La

rge

fo

llic

les

(>1

4 m

m)

0

2

4

6

8

10

12

14

Me

diu

m f

oll

icle

s(1

0-1

4 m

m)

0

2

4

6

8

10

12

Sm

all

fo

llic

les

(<1

0 m

m)

0

1

2

3

4

5

6

7

0

2

4

6

8

10

12

14

0

2

4

6

8

10

12

0

1

2

3

4

5

6

7

Group A - hMG Group B - rFSH

H P H P

* *

**

H = day of lowH = day of low--dose hCG startdose hCG start

P = preovulatoryP = preovulatory

Clinical outcomeClinical outcomeFilicori et al, Fertil Steril 84:394, 2005Filicori et al, Fertil Steril 84:394, 2005

<0.001<0.001808±41808±411,146±661,146±66€€gonadotropin costgonadotropin cost

NSNS2.5±0.12.5±0.12.3±0.22.3±0.2nnembryos transferredembryos transferred

NSNS84±584±586±686±6%%good quality embryosgood quality embryos

%%

%%

nn

IUIU

daysdays

daysdays

daysdays

NSNS25252121pregnancy ratespregnancy rates

<0.001<0.00174±374±348±448±4fertilization ratesfertilization rates

NSNS8.2±0.68.2±0.68.0±0.88.0±0.8mature oocytesmature oocytes

<0.001<0.0011,960±991,960±992,779±1602,779±160rFSH/hMG doserFSH/hMG dose

--3.3±0.13.3±0.1--daily hCG durationdaily hCG duration

<0.001<0.0018.6±0.18.6±0.111.6±0.211.6±0.2rFSH/hMG durationrFSH/hMG duration

NSNS11.9±0.111.9±0.111.6±0.211.6±0.2overall treatment durationoverall treatment duration

PPgroup Bgroup B

(hCG)(hCG)

group Agroup A

(no hCG)(no hCG)

Selective use of LH activity in the late stagesSelective use of LH activity in the late stages

of ovulation induction and COSof ovulation induction and COS

higher pregnancy rateshigher pregnancy ratesCOS for IUICOS for IUIhCG 250 IUhCG 250 IUDehghaniDehghani, 2006, 2006

trends toward reduced OHSStrends toward reduced OHSSCOSCOS--antanthCG 200 IUhCG 200 IUKoichi, 2006Koichi, 2006

reduced cost of COSreduced cost of COSCOSCOShCG 200 IUhCG 200 IUGomes, 2007Gomes, 2007

applicability confirmed in clinical settingapplicability confirmed in clinical settingCOSCOShCG 200 IUhCG 200 IUFilicori, 2005Filicori, 2005

clinical applicability in antagonist cyclesclinical applicability in antagonist cyclesCOSCOS--antanthCG 200 IUhCG 200 IUSerafiniSerafini, 2006, 2006

applicability in antagonist cyclesapplicability in antagonist cyclesCOSCOS--antantrCG 8 µgrCG 8 µgKenigsbergKenigsberg, 2006, 2006

applicable in clomid OIapplicable in clomid OIclomid OIclomid OIhCG 200 IUhCG 200 IUBraniganBranigan, 2005, 2005

prevention of OHSSprevention of OHSSPCOSPCOShCG 200 IUhCG 200 IULee, 2005Lee, 2005

pregnancy with rLH alone in LFP in HH ptpregnancy with rLH alone in LFP in HH ptOIOIrLH 375 IUrLH 375 IUFabreguesFabregues, 2003, 2003

first pregnancy with low dose hCG alone first pregnancy with low dose hCG alone

in LFPin LFPCOSCOShCG 200 IUhCG 200 IUFilicori, 2002Filicori, 2002

LFP low dose hCG alone supports LFP low dose hCG alone supports

folliculogenesis and steroidogenesisfolliculogenesis and steroidogenesisCOSCOShCG 200 IUhCG 200 IUFilicori, 2002Filicori, 2002

outcome of hCG/rLH administrationoutcome of hCG/rLH administrationregimenregimentype/dosetype/dose


Summary

�� GnRH agonists can be effectively used to trigger final GnRH agonists can be effectively used to trigger final

follicle maturation in GnRH antagonist cyclesfollicle maturation in GnRH antagonist cycles

�� use of FSH preparations with different sialic acid use of FSH preparations with different sialic acid

content and pharmacokinetics can affect clinical content and pharmacokinetics can affect clinical

outcome of ovarian stimulationoutcome of ovarian stimulation

�� availability of longavailability of long--acting rFSH provides alternative acting rFSH provides alternative

approaches to traditional ovarian stimulationapproaches to traditional ovarian stimulation

�� novel lownovel low--dose hCG regimens markedly lower COS cost dose hCG regimens markedly lower COS cost

and may provide therapeutic advantages such as and may provide therapeutic advantages such as

reductions in OHSS occurrencereductions in OHSS occurrence

clinical

G. E. Cognigni

W. CiampagliaF. Infante

P. PocognoliC. Tabarelli

laboratory

L. Parmegiani

S. BernardiA. Maccarini

E. NikitosE. Troilo

GynePro RiproduzioneGynePro Riproduzione

BolognaBologna

Documents

Nuove Tecniche di Stimolazione dell’Ovulazione Multipla · Controlled ovarian stimulation Goals to induce multiple folliculogenesis in patients candidate for assisted reproduction