HX4 as a PET Companion Diagnostic for Hypoxia-Targeted Drugs

Katrin Szardenings

NN

NO2

N NN

OH

18F

P

HN

ONH

ON

NO2N

Br

Br

Rx

Dx

2

Introduction: Threshold Pharmaceuticals

• Building a broad therapeutic platform in cancer – Based upon selectively targeting tumor hypoxia

• A fundamental property of solid tumors as well as some hematologic cancers • A significant unmet medical need

– And including the HX4 hypoxia PET imaging agent acquired from Siemens in 2013

• Discovered and developing TH-302 – Industry’s most advanced hypoxia targeted anti-cancer compound in active

development • Partnered with Merck KGaA

• Pivotal studies underway in 2 indications – Phase 3 in soft tissue sarcoma – Phase 3 in pancreatic cancer

• Earlier stage studies underway in a variety of indications

3

Tumor Hypoxia Overview – Hypoxia is a feature of all solid

tumors – Hypoxic conditions are created by

rapid cell proliferation and development of a disordered vascular network

– Hypoxic cells are resistant to traditional chemotherapy and radiation

– Tumor hypoxia is associated with a poor prognosis, aggressive phenotype, metastasis and relapse

150µm

Blood Vessels

Hypoxic region Necrosis

Minchinton, AI & Tannock , IF. Nat Rev Cancer. 2006; 6:583-92.

Blood vessels (CD31)

Hypoxic regions (Pimonidazole)

HCT-116 CRC model

Oxic region

4

The More Hypoxic, the Worse the Prognosis Three examples from many published studies

Reviewed in Vaupel, P. & Mayer, A. Cancer Metastases Rev 26 225, 2007

pO 2 ? 10 mmHg (n = 41)

pO 2 ? 10 mmHg

Head and Neck Cancer (n = 63 pts)

Cervical Cancer (n = 89 pts)

Soft Tissue Sarcoma (n = 28 pts)

pO 2 < 10 mmHg pO 2 < 10 mmHg

(n = 48)

pO 2 ? 19 mmHg (n = 14)

pO 2 < 19 mmHg (n = 14)

100

80

60

40

20

0

100

80

60

40

20

0

100

80

60

40

20

0

Sur

viva

l (%

)

Sur

viva

l (%

)

Sur

viva

l (%

)

Time (months) 12 24 36 48 0 10 20 30 40 0 50 60 70 80

Time (months) Time (months) 12 24 36 48 0 60

Brizel , D.M. et al. Radiother . Oncol . 53 : 113 - 117, 1999

Hockel,M . et al. Cancer Res . 56 : 4509 - 4515, 1996

Nordsmark,M . et al. Brit. J. Cancer 84 : 1070 - 1075, 2001

pO 2 ? 10 mmHg (n = 41)

Head and Neck Cancer (n = 63 pts)

Cervical Cancer (n = 89 pts)

Soft Tissue Sarcoma (n = 28 pts)

(n = 14)

pO 2 < 19 mmHg (n = 14)

100

80

60

40

20

0

100

80

60

40

20

0

100

80

60

40

20

0

Sur

viva

l (%

)

Sur

viva

l (%

)

Sur

viva

l (%

)

Time (months) 12 24 36 48 0 10 20 30 40 0 50 60 70 80

Time (months) Time (months) 12 24 36 48 0 60

Brizel , D.M. et al. Radiother . Oncol . 53 : 113 - 117, 1999

Hockel,M . et al. Cancer Res . 56 : 4509 - 4515, 1996

Nordsmark,M . et al. Brit. J. Cancer 84 : 1070 - 1075, 2001

pO 2 < 10 mmHg (n = 48)

pO 2 > 10 mmHg _

pO 2 > 10 mmHg _ pO 2 > 19 mmHg _

(n = 19)

(n = 41)

pO 2 < 10 mmHg (n = 44)

5 Tumor Hypoxia and Poor Clinical Prognosis Treatment failure and metastatic progression

• Hypoxia is associated with treatment failure – Both radiotherapy and chemotherapy resistance

– Quiescent hypoxic cells resist anti-proliferative therapy

• Hypoxia yields a more aggressive, invasive, metastatic phenotype – Upregulates survival factors; inhibits apoptosis

– Stimulates production of enzymes mediating invasiveness

– Induces angiogenic signals

– Promotes genetic and epigenetic changes

– Promotes the epithelial to mesenchymal transition (EMT)

– Cancer stem cells (CSCs) can reside in the hypoxic compartments

Tumor hypoxia can also be the basis for selective targeting by HAPs (hypoxia-activated prodrugs)

5

6

TH-302 Overview, the “cart”

• TH-302 is a small molecule prodrug that releases the potent DNA-alkylating agent, Br-IPM, via reductases under hypoxic conditions.

• 1,000 patients have been treated with TH-302 in clinical trials to date demonstrating antitumor activity: – across multiple tumor types (solid tumors and hematological malignancies) – as a single agent and in combination with chemotherapy/antiangiogenics – with a consistent safety profile and manageable toxicity

N

N

HC

O2N

OHN

P

O

NH

Br

Br

Hypoxia Trigger

TH-302 (inert prodrug)

H N

PO

O

NH

Cl

Cl

-

H

Br

Br

Br-IPM (active cytotoxin)

Normoxia Hypoxia

Oxygen Gradient

5% O2 0.5% O2

7

TH-302: Current Clinical Trials

Study Name Indication Combination Therapy Target # Pts. Phase 1 Phase

1/2 Phase 2 Phase 3

TH-CR-406 Soft Tissue Sarcoma doxorubicin 620

MAESTRO Pancreatic Cancer gemcitabine 660

TH-CR-413 Advanced Melanoma single agent 40

TH-CR-408 Multiple Myeloma bortezomib 60

IST-4003 Glioblastoma bevacizumab 28

TH-CR-410 RCC, GIST, PNET sunitinib 58

IST-4004 RCC, HCC sorafenib 48

TH-CR-407 Advanced Leukemias single agent 49

EMR200592-002 Pancreatic Cancer (Japan) gemcitabine 30

IST-4001 Various solid tumors pazopanib 50

EMR200592-006 Pancreatic Cancer Gemcitabine + nab paclitaxel 48

∗ ∗

∗ Registration trial being conducted under a Special Protocol Agreement (SPA) with the FDA Antiangiogenic agents Threshold-sponsored trial

Merck KGaA-sponsored trial Investigator-sponsored trial Planning: Ph 2 NSCLC 2nd line + pemetrexed, 440 Pts.

8

TH-302, pimonidazole, and [18F]-HX4 … • Have the same ‘trigger’ for hypoxia: 2-nitroimidazole • Require the same reductases for one-electron reduction • Have similar oxygen concentration dependence for activation HX4 and TH-302 will “see” the same hypoxic areas as pimonidazole

does

Introduction: Dx [18F]-HX4, the horse

[18F]-HX4 autoradiography

Pimonidazole stain

9

H460 Tumor 786-O Tumor

High HX4 signal Low HX4 signal

Highly Hypoxic Tumor Low hypoxia Tumor

High Pimonidazole

signal

Low Pimonidazole

signal

Siemens Collaboration: [18F]HX4 in Xenograft Models [18F]HX4 signal correlates with pimonidazole staining

10

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Day 0 Day 4

T/M

(Upt

ake

of H

X4) *

(n=17) (n=17)

[18F]-HX4 as a ‘Response Biomarker’: Reduced [18F]HX4 signal after TH-302 in H460 xenograft model

0.00.51.01.52.02.53.03.54.04.5

Day 0 Day 4

T/M

(Upt

ake

of H

X4 )

2-12-22-32-42-52-62-72-82-92-102-112-123-33-73-93-143-18

TH-302 150mg/kg

[18F]-HX4 [18F]-HX4

72hr 24hr

11

Siemens: stand-alone hypoxia PET tracer prognostic imaging agent regulatory hurdles:

Proof of concept trials: does HX4 measure hypoxia? What is the gold standard of measuring hypoxia? (Eppendorf probe

is the only approved device, but no longer available; pimonidazole doesn’t count; areas of hypoxia are in-homogenous and biopsies therefore flawed..)

How would HX4 (or knowing about hypoxia) benefit the patient? How would clinical management change, since there is no hypoxia

specific drug?

Threshold: companion Dx to TH-302 predictive imaging agent TH-302 and HX4 have the same molecular target TH-302 provides treatment for patients selected with HX4

The future for HX4 has changed

12

Past HX4 Clinical Experience (Siemens, P. Lambin/Maastro)

Lung H&N Cervical CRC Thymus 40 29 6 11 2

US EU Asia Fox Chase Cancer Center (PA)

USC (CA) Holy Name (NJ) UC Irvine (CA)

Cedars Sinai Medical Center (CA) UMDNJ (NJ) U Iowa (IA)

Cleveland Clinic (OH) Lakenau Institute for Medical research(PA)

Eastern Regional Medical Center (PA) Boston Medical Center (MA)

The Angeles Clinic and Research Institute (CA)

Maastro (Netherlands) Fudan University (Shanghai, CN) Samsung (Korea)

Asan (Korea)

[18F]HX4 Imaged Patients

[18F]HX4 Clinical Sites

13

A total of 39 patients had two interpretable pre-treatment [F-18]HX4 PET/CT scans and were included in the reproducibility of [F-18]HX4 uptake: • 12 head/neck • 12 lung • 9 rectal • 6 cervical

First and second pre-treatment uptake parameters (SUVMax, SUVMean

and T/B ratio) were highly correlated and statistically significant (P<0.001).

Going forward: • There is a sufficient range of hypoxia in these types of cancers providing a

base for selecting a hypoxia threshold • Method to analyze hypoxia and selecting the appropriate cut-off is important

HX4 200 Study: A pilot, Phase 2, multi-center, open-label, non-randomized, study in patients with confirmed cancer (Siemens)

14

Results Summary for HX4-200 by cancer type

Head & Neck

1.00

1.50

2.00

2.50

3.00

3.50

4.00

0302 0303 0305 0306 0308 0309 0803 0804 0908 1001

T/B

max

/mea

n/pe

ak

Patient ID

1.00

1.50

2.00

2.50

3.00

3.50

4.00

0101 0102 0301 0304 0310 0506 0507 0601 0801 0902 0906 0907

T/B

max

/mea

n/pe

ak

Patient ID

1.00

1.50

2.00

2.50

3.00

3.50

4.00

0403 0405 0406 0501 0508 0903 0904 0905 1002

T/B

max

/mea

n/pe

ak

Patient ID

Cervical

1.00

1.50

2.00

2.50

3.00

3.50

4.00

0204 0307 0505 0509 1004

T/B

max

/mea

n/pe

ak

Patient ID

Lung

Rectal

15

[18F]HX4 can measure hypoxia in lung cancer (Siemens)

Significant Hypoxia

Minimal/No Hypoxia

Low-Hypoxic Lung Cancer (Right lung mass)

Hypoxic Lung Cancer (Left lung mass)

16

[18F]HX4 can measure hypoxia in SCCHN (Siemens)

Significant Hypoxia

Minimal/No Hypoxia

Hypoxic H&N Cancer (Right Maxillary Mass)

Low-Hypoxic H&N Cancer (Palate mass)

17

Companion Dx Clinical research tool Stand-alone Dx

Label: “For use in identifying hypoxic tumors in patients being considered for treatment with TH-302”

Label: “For the identification of hypoxic tumors”

TH-302 HX4 PET

Therapy

HX4 PET HX4 PET

HX4 PET

Development options for HX4:

Elucidates presence of hypoxia in patients; Supports mechanism for TH-302 “For use in identifying hypoxic tumors in patients being considered for treatment with TH-302”

18

Clinical phase: proof of concept studies (generate data!) are now beginning

Can HX4 select patients that will respond better to TH-302

treatment? Make HX4 available as THE hypoxia imaging agent to

investigators (with or without TH-302) Increase awareness of hypoxia and learn more about HX4 Find possible new patient populations for TH-302

Need data to start discussions with the FDA with a clear vision of clinical utility & label

Decide on commercialization path or keep as clinical research tool

HX4 as a companion Dx: one step at the time

19

Lesson: Setting up HX4 production is costly! • IND research uses only needs few clinical and manufacturing sites to

help understand value • Currently setting up clinical sites which can participate in TH-302 clinical

development AND have PET manufacturing capabilities • Continue chemistry improvements for HX4 with commercial

manufacturer (PETNET?) to optimize commercial build-out only if needed

Manufacturing/supply chain

20 Current sites for HX4 clinical production: North America

• Toronto (CPDC) ready in March • NCM (New York): currently being set up • Philadelphia: PETNET ready • Los Angeles (Culver City): PETNET ready

21

Current sites for HX4 clinical production: Europe/UK

21

• Nottingham/UK: PETNET ready • Amsterdam/Netherlands, VU University Medical Center ready

22

What is the most clinically valuable imaging information: • Binary result (hypoxic, yes or no?)? • Quantitation (how much hypoxia, hypoxic fraction)? • When should the patient be scanned: baseline? After one cycle of

treatment (response biomarker)?

If an imaging outcome is rare (e.g. mostly positive/negative)

how is it valuable to TH-302?

Value claims and price driven by • Relative cost of HX4 to TH-302 • How HX4 intervention improves patient outcome

The value of HX4 imaging information

23

Preclinical studies with HX4 and TH-302 look very promising

Clinical experience with HX4 (no TH-302) indicates that HX4 is a superior hypoxia PET tracer

Proof of concept studies with TH-302 in the clinic (currently ongoing): does it work? Does patient selection by HX4 significantly improve TH-302 response rates? • HX4 predicts outcome for TH-302 • In what patient group?

Key milestones for HX4