0.01 0.1 1 10 100 1000 10000100000-25

0

25

50

75

100

125

KYM-003 [nM]

Gro

wth

inhi

bitio

n(%

cont

rol)

MOLM-16SU-DHL-1

Small Molecule-Induced, Selective STAT3 Degradation Leads to Anti-Tumor Activity in STAT3-Dependent Heme Malignancies

Fred Csibi, Bin Yang, Karen Yuan, Michele Mayo, Haojing Rong, Scott Rusin, Kirti Sharma, Henry Li, Sharon Townson, Hari Kamadurai, Mike Sintchak, Yogesh Chutake, Jesse Chen, Christine Loh, Jared Gollob, Duncan Walker, Nan Ji and Nello Mainolfi, Kymera Therapeutics, Inc. 300 Technology Square, Cambridge, MA 02139. Contact: fcsibi@kymeratx.com

KYM-003 causes rapid, potent, and highly selective degradation of STAT3 in multiple cellular systems

Introduction

Conclusions

Disclosures: Csibi, Yang, Mayo, Yuan, Rong, Rusin, Sharma, Li, Townson, Kamadurai, Sintchak, Chutake, Gollob, Walker, Ji and Mainolfi: Kymera Therapeutics: Employment, Equity Ownership.

STAT3 integrates multiple upstream signaling events to regulate a wide variety of cellular functions

3803

• Targeted protein degradation is a new therapeutic modality that expands the abilityto target difficult-to-drug oncogenic proteins.

• STAT3 is a transcription factor downstream of several signaling events including theIL-6/JAK pathway.

• Activating mutations and aberrant activation of STAT3 drive a subset of tumors viainduction of autocrine factors that promote tumor proliferation and survival, as wellas induction of proteins that may contribute to a tumor permissive environment.

• STAT3 is therefore a highly attractive target for oncology. However, potent andselective agents specifically and directly targeting STAT3 have remained elusive.

• Degrading STAT3 will abrogate the JAK/STAT3 signaling axis to induce tumor celldeath.

• Kymera Therapeutics is developing degraders of STAT3 with drug-like properties,represented here with KYM-003 and its analog compound A. These compoundspotently and selectively degrade STAT3 protein and display strong anti-tumoractivity in models of heme malignancies.

Deep Tandem Mass Tag proteomics at 8h (>10,000 proteins detected) demonstrates selective STAT3 degradation

KYM-003 represses the growth of multiple heme cell lines

Overview of targeted protein degradation

BROAD OPPORTUNITYONLY BINDING SITE REQUIRED

EFFICIENTCATALYTIC

PROLONGED IMPACTTARGET PROTEIN DEGRADATION

HITCHING A RIDEUPS INTACT & FUNCTIONAL

• Kymera has developed potent and highly selective STAT3 degraders with activity againstmutant and wild type STAT3.

• Sustained STAT3 degradation of 90% or greater leads to apoptosis induction and cancer celldeath within 48 hours in vitro and in vivo.

• STAT3 degraders are active in models of heme malignancies including ALCL and AML,supporting these as potential initial indications for clinical development.

• Kymera plans to develop STAT3 degraders in a variety of oncology and immunologyindications.

KYM-003 leads to significant regression in SU-DHL-1 tumor xenograft model at well tolerated doses

A sustained and robust degradation of STAT3 with KYM-003 leads to profound anti-tumor activity in vitro and in vivo

-Log

10p-

valu

e

Log2 fold change (100 nM KYM-003 / DMSO)

SU-DHL-1

-ΔS701

p=0.05

PIM1 is regulated by STAT3

Endogenous STAT3-HiBiT live cell assay (A549 cells)

KYM-003 degrades both wild-type and mutant STAT3 in heme cell lines

0.1 1 10 100 1,000 10,000

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KYM-003 [nM]

STA

T3 p

rote

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MOLM-16 (AML): 4nMSU-DHL-1 (T cell lymphoma): 28nM

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Compound A [nM]

STAT

3 pr

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HDLM-2 (Hodgkin's lymphoma): 68nM

STAT3WT (DC50, MSD, 24 hr) STAT3D661Y (DC50, WB, 24 hr)

0.1 1 10 100 1000 10000 1000000

25

50

75

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150

KYM-003 [nM]

mRN

A le

vels

(%co

ntro

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SOCS3

PD-L1STAT3

Gene IC50 (μM) / % Max inhibition, 24 hr

SOCS3 0.185 / 87

STAT3 0.141 / 62

PD-L1 0.058 / 82

KYM-003 decreases STAT3-dependent gene expression

RT-qPCR in SU-DHL-1 cells, 24 hrMolm-16

Log2 fold change (30 nM KYM-003 / DMSO)

-ΔS701

KYM-003 treatment leads to apoptosis induction and cell cycle defects in SU-DHL-1 lymphoma line

24 hours 48 hours 72 hours 96 hours 24 hours 48 hours 72 hours 96 hours0

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KYM-003, 500nMDMSO, 0.1%

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(%Po

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Ki-6

7 Ex

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(%Po

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500nM KYM-003

KYM-003 treatment induces apoptosis at 48 hr that leads to cell death

Time-dependent inhibition of proliferation with KYM-003

Increase in subG1 cells (PI/RNAse analysis, FACS)

Cell line Tumor type CTG, GI50 μM (%Max inh), Day 4

SU-DHL-1 (shown) ALCL (ALK+) 0.167 (>95) MOLM-16 (shown) AML 0.016 (80)

A3/KAW DLBCL 1.9 (50-55)

SUP-M2 ALCL (ALK+) 0.61 (>95)

DEL ALCL (ALK+) 0.11 (>95)

KARPAS-299 ALCL (ALK+) 0.14 (50-55)

SR-786 ALCL (ALK+) 3.8 (75)

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(MSD

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Cell Growth

STAT3 levels

48 hr treatment wash-out

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(MSD

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Cell Growth

STAT3 levels

24 hr treatment wash-out

Wash-out study demonstrates sustained degradation is required for SU-DHL-1 cells to commit to death

A decrease of STAT3 by 90% is necessary to induce SU-DHL-1 apoptosis and inhibit cell growth

Assay SU-DHL-1STAT3 levels, MSD DC90 (μM) at 24 hr 0.15

Apoptosis, Caspase3/7-Glo IC50 (μM) at 48 hr 0.38

Growth inhibition, CTG IC50 (μM) at 96 hr 0.167

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48hr24hr8hr

0hr

-Log

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p=0.05

Cou

nt

Cou

nt

STAT3-PE-A STAT3-PE-A

DMSO KYM-003, 500nMDecrease of STAT3 at 24 hours

JAK JAK

GPCRs

STAT3 STAT3P

STAT3 STAT3P

STAT3

GFRs

STAT3Degrader

[KYM-003]

IL-6Rs

IL-6 Family Cytokines

Nucleus

Oncology:Survival and Proliferation

DifferentiationAngiogenesis and EMT

Immunity:Th17 differentiation

InflammationM1/M2 polarization

Treg function

STAT3MUT

XXX

SRC ALK

P

P

P

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Tum

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Bod

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Robust degradation of STAT3 for 48hr in tumor with single dose of 50mpk ip

0.01 0.1 1 10 100 1000 10000 10000075

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STAT3 levels (MSD, 24 hr)Apoptosis (Caspase3/7-Glo, 48 hr)Growth inhibition (CTG, 96 hr)

90% degradation