# Presentation: 223671

## Strategy, Issues, and Alternative Approaches in Development of a Treatment for HUS Prevention

**Advisory Committee Meeting **
**12 April 2007**

**Teijin America, Inc.**

## Working Framework

- Clinical outcomes data are primary source for safety and efficacy
- Limitations on the availability and utility of clinical outcomes
- Clinical outcomes data need to be supplemented with nonclinical data

## Purpose

- To outline the potential data sources for establishing safety and efficacy of agents to prevent HUS
- To show how data from nonclinical sources can be used to supplement clinical data

## Information Required for Package Insert

** ****Patient population**
** ****Timing of treatment**
** ****Dose**
** ****Dose regimen**
** ****Clinical benefit**
** ****Potential risks**

**Notes:**
Cato:  I put this slide here, even before the Presentation Overview, because it enables a nice tie-in to this information later.  I think the presentation could begin with a statement something like "This is what we ultimately want.  Now let's discuss how we think it is possible to obtain this information for treatments for HUS"

## Desired Indication 

**For the prevention of HUS in pediatric patients with watery or bloody diarrhea **
**and **
**O157-positive or SLT-positive stool sample **

- Desired Indication

**Notes:**
What is the meaning of “SLT-2-positive (slowest test)”?
Please search publication(s) of SLT-1, SLT-2, and SLT-1/2 ratio in US.
We should justify administration of TMA-15 in the case of “SLT” diagnosis.

## Presentation Overview

**Clinical Course of Shiga-like Toxin Producing *****E. coli***** (STEC) Infection and HUS**
**Approach for Therapeutic Intervention**
**Potential Corroborative Outcomes**
**Integrating Clinical and Preclinical Data for Evidence of Efficacy and Safety**
**Conclusions**

## STEC Infection Progresses to HUS

**Diarrhea and STEC-Positive**

**HUS**

**1 - 8 days**

**100**

** ****10**

**4**

**1**

**30****-50%**

**4****-15%**

** ****5****-15%**

- Example:

**Notes:**
Characteristically disease of young children
Life-threatening cause of acute renal failure
Poor prognosis
50% of cases develop long-term sequelae:
Chronic renal diseases (30%); hypertension, seizures, blindness, paralysis
20% of cases progress to end-stage renal disease
3 to 5% mortality 

## Current Supportive Therapies

- Antibiotics

- Antimotility agents

**Hydration**

**Dialysis**

- Plasma
- exchange

- STEC proliferation
- in the gut

- SLT-2 production

- Systemic SLT-2

- Cellular injury

- HUS, encephalopathy, death

- Gb3 receptor

**Notes:**
Different STEC strains produce different Shiga-like toxins (SLTs), i.e., Shiga like toxin 1 (SLT-1), or Shiga-like toxin 2 (SLT-2), or both.  
SLT-2 is more toxic (several hundreds~1000 times) than SLT-1 and the major causative agent for developing HUS after STEC infection.
Using antibiotics in STEC infection is controversial.

## Approach for Therapeutic Intervention

## Traditional Drug Development

- Target a critical step in the pathophysiology of the disease
- Analyze the protective effect in animal models
- Assess safety and PK preclinically
- Assess safety and PK in healthy adult human subjects
- Assess safety and PK in patient population
- Statistically significant randomized clinical studies

**Notes:**
“Strategy” corresponds to the title of this presentation.

## Traditional Drug Development

- Target a critical step in the pathophysiology of the disease
- Analyze the protective effect in animal models
- Assess safety and PK preclinically
- Assess safety and PK in healthy adult human subjects
- Assess safety and PK in patient population
- Large Randomized Clinical Studies
**We will present Teijin data to illustrate the practicality of this approach**

**Notes:**
“Strategy” corresponds to the title of this presentation.

## Traditional Drug Development

**Target a critical step in the pathophysiology of the disease**
- Analyze the protective effect in animal models
- Assess safety and PK preclinically
- Assess safety and PK in healthy adult human subjects
- Assess safety and PK in patient population
- Statistically significant randomized clinical studies

**Notes:**
“Strategy” corresponds to the title of this presentation.

## SLT-2 is Critical for the Majority of HUS Cases

- STEC proliferation
- in the gut

- SLT-2 production

**Systemic SLT-2**

- Cellular injury

- HUS, encephalopathy, death

- Gb3 receptor

**TMA-15**

**X**

**Notes:**
Different STEC strains produce different Shiga-like toxins (SLTs), i.e., Shiga like toxin 1 (SLT-1), or Shiga-like toxin 2 (SLT-2), or both.  
SLT-2 is more toxic (several hundreds~1000 times) than SLT-1 and the major causative agent for developing HUS after STEC infection.
Using antibiotics in STEC infection is controversial.

## TMA-15 Neutralizes SLT-2in Cell Culture

**112**

**17**

**3**

**198**

**193**

**0**

**50**

**100**

**150**

**200**

**0**

**5**

**10**

**TMA-15 (μg/ml)**

** ****STEC Isolates**
**Neutralized**

## Target Concentration of TMA-15 is ≥10 μg/ml

**112**

**17**

**3**

**198**

**193**

**0**

**50**

**100**

**150**

**200**

**0**

**5**

**10**

**TMA-15 (μg/ml)**

** ****STEC Isolates**
**Neutralized**

## Traditional Drug Development

- Target a critical step in the pathophysiology of the disease
**Analyze the protective effect in animal models**
- Assess safety and PK preclinically
- Assess safety and PK in healthy adult human subjects
- Assess safety and PK in patient population
- Large Randomized Clinical Studies

**Notes:**
“Strategy” corresponds to the title of this presentation.

## TMA-15 Prevents SLT-2-Induced Mortality in Mice

| Dose of TMA-15 (i.v.)  |  # Mice surviving* / 
# Mice injected with 10X LD50 SLT-2 |
| --- | --- |
| 0  | 0 /10 |
| 0.15 g/mouse | 1 /10 |
| 0.31 g/mouse | 1 /10 |
| 0.62 g/mouse | 4 /10 |
| 1.23 g/mouse | 10 /10 |

- * Survival determined 7 days after SLT-2 injection

**Notes:**
† 59 ng/head (10 times the LD50) of SLT-2 were injected i.p. 1-hr after TMA-15 dose.
‡ The doses of 0.15, 0.31, 0.62, and 1.23 micro-g/head of TMA-15 corresponded to 1.25, 2.5, 5 and 10 times that of SLT-2 on a molar basis, respectively. 

## TMA-15 Prevents STEC-Induced Mortality in Mice

**0**

**20**

**40**

**60**

**80**

**100**

- 1

**TMA-15 (mg/kg )**
**(Single dose, 24 hours **_**after**_** inoculation with STEC)**

**0/20**

**11/20**

**17/20**

**20/20**

**20/20**

**10 Day **
**Survival**
**(%)**

## SLT-2 Concentrations Peak at ~48 Hours in STEC-Infected Mice

- Time After STEC Infection (hours)

- Serum SLT-2
- (pg/ml)

## TMA-15 Prevents Mouse Mortality when Administered up to 24 Hours after Challenge with STEC

**-1hour**

**+12 hours**

**+24 hours**

**TMA-15 administration (single dose of 2.5 mg/kg)**

- 0/5

- 1/5

- 2/5

- 3/5

- 4/5

- 5/5

**Mouse Survival at 10 Days**

**+48 hours**

## TMA-15 is Most Effective When Given Prior to Peak SLT-2 Concentrations

**1****hr before**

**12 ****hr after**

**24 ****hr after**

**Mouse **
**Survival**

**48 ****hr after**

**Blood SLT-2**

## Traditional Drug Development

- Target a critical step in the pathophysiology of the disease
- Analyze the protective effect in animal models
**Assess toxicity and PK preclinically**
- Assess safety and PK in healthy adult human subjects
- Assess safety and PK in patient population
- Statistically significant randomized clinical studies

**Notes:**
“Strategy” corresponds to the title of this presentation.

## Preclinical Assessment

- Mouse PK and PD
- Mouse toxicity
- Monkey PK
- Monkey toxicity
- Cross-reactivity with human tissue panel

## No Toxicity Observed with TMA-15

- Mice at doses up to 2.5 mg/kg
- No toxicity noted
- t1/2 ~14 days
- Monkeys at doses of up to 20 mg/kg
- Dose is >6X the predicted effective dose in humans
- No toxicity noted
- t1/2 ~12 days
- No anti-TMA-15 antibodies observed
- No cross-reactivity of TMA-15 with human tissues

## TMA-15 PK in Monkeys

- 1

- 10

- 100

- 1000

- 0

- 48

- 96

- 144

- 192

- 240

- 288

- 336

**Time post-dose (Hours)**

**TMA-15 **
**(μg/mL)**

- Males 20 mg/kg

- Females 20 mg/kg

## Traditional Drug Development

- Target a critical step in the pathophysiology of the disease
- Analyze the protective effect in animal models
- Assess toxicity and PK preclinically
**Assess safety and PK in healthy adult human subjects**
- Assess safety and PK in patient population
- Statistically significant randomized clinical studies

**Notes:**
“Strategy” corresponds to the title of this presentation.

## Phase 1 Study Design

- Randomized, double-blind, placebo controlled, dose-escalating study
- Healthy adult volunteers
- Single i.v. infusion
- 32 Subjects
- 8 Placebo
- 24 TMA-15 (0.1, 0.3, 1.0 or 3.0 mg/kg)

## Phase 1 Study PK Results

- Dose-proportional Cmax and AUC(0-inf)
- Terminal half-life was consistent across doses
- Mean plasma concentration remained above 10 μg/mL
-  For ~4 days at 1 mg/kg
-  For >21 days at 3 mg/kg

**Notes:**
T1/2(days)                  
0.1mg/kg; 28.1 (10.2) 
0.3mg/kg; 29.0 (9.57)
1.0mg/kg; 26.6 (4.72)
3.0mg/kg; 24.6 (5.03)  

## Phase 1 Study Safety Results

- No AEs considered related to TMA-15
- No evidence of antigenicity
- TMA-15 was safe and well-tolerated at all doses (0.1, 0.3, 1.0, and 3.0 mg/kg)

## Traditional Drug Development

- Target a critical step in the pathophysiology of the disease
- Analyze the protective effect in animal models
- Assess toxicity and PK preclinically
- Assess safety and PK in healthy adult human subjects
**Assess safety and PK in patient population**
- Statistically significant randomized clinical studies

**Notes:**
“Strategy” corresponds to the title of this presentation.

## Phase 2 Study Design

-  Randomized, double-blind, placebo controlled
-  STEC(+) subjects ages 1 to 15
-  BD  _<_ 72 hrs at time of treatment
-  Single i.v. infusion
-  Placebo (n=36)
-  1 mg/kg (n=38)
-  3 mg/kg (n=35)
- Safety, PK
- Efficacy

## Phase 2 Study Enrollment

-  Canada, US sites
-  8 subjects from 6 sites within a season
-  Argentinean sites
-  101 subjects from 7 sites in 13 months
-  110 subjects randomized
-  109 subjects treated within 72 hours of onset of BD
-  Subjects followed for 4 months

## Phase 2 Study PK Results

-  Pediatric PK similar to healthy adult PK
-  Mean plasma concentration remained above 10 μg/mL
-  For ~4 days at 1 mg/kg
-  For >22 days at 3 mg/kg

## TMA-15 Pharmacokinetics in Pediatric Patients

- 0

- 10

- 20

- 30

- 40

- 50

- 60

- 70

- 0

- 7

- 14

- 21

- 28

- 35

- 42

- 49

- 56

- Days

- Serum TMA-15 (μg/mL)

- 3 mg/kg (n= 35)

- 1 mg/kg (n=38)

## Phase 2 Study Safety Results

- Few differences observed in lab values, vital signs or AEs
- Fewer SAEs noted with TMA-15 (24%, 17%) vs placebo (28%)
- Two deaths; unrelated to TMA-15
- 1 in placebo group due to HUS
- 1 in 1 mg/kg group due to *Klebsiella pneumoniae*
-  No evidence of antigenicity at 1 or 3 mg/kg
-  No identified safety issues with TMA-15 clinically

## Traditional Drug Development

- Target a critical step in the pathophysiology of the disease
- Analyze the protective effect in animal models
- Assess toxicity and PK preclinically
- Assess safety and PK in healthy adult human subjects
- Assess safety and PK in patient population
**Statistically significant randomized clinical studies**

**Notes:**
“Strategy” corresponds to the title of this presentation.

## Limitations of Traditional Development Model

- STEC infection is sporadic
- STEC infection is infrequent
- HUS is an uncommon complication of STEC
- Few options for enrichment for patients at risk of HUS
- 	In the Teijin Phase 2 Study, only ~8%  of patients (109/1368) screened could be enrolled

## Sample Size Estimates for a Single Statistically-Significant Study of HUS

| Assumptions |  | Estimates* |  |  |  |
| --- | --- | --- | --- | --- | --- |
| HUS Incidence | Treatment Effect 
(% reduction) | Subjects Needed for Two Treatment Arms |  | Projected Number of HUS Cases |  |
|  |  | Screening
(Bloody Diarrhea) | Enrollment
(STEC +)  |  |  |
|  |  |  |  | Drug
treated | Placebo treated |
| 10% | 50 | 13,384 | 1162 | 31 | 62 |

- *For 90% power at α = 0.05

- Projected Study Duration is >14 years

**Notes:**
Only a fraction of patients screened can be enrolled
Not feasible to obtain statistically significant demonstration of a reduction of HUS incidence
Enrollment cannot be accelerated by simply adding more sites or relying on outbreaks

## Not feasible to conduct an adequately powered study that demonstrates a statistically significant prevention of HUS as the primary endpoint 

Need to generate data from other corroborative measures of efficacy

- Need to generate data from other corroborative measures of efficacy

## Potential Corroborative Outcomes

- Clinical
- Dose effects
- Timing of treatment
- HUS Severity
- Progression from WD to BD
- SLT-2 blood concentration
- Nonclinical
- SLT-2-Induced mortality
- STEC-Induced mortality
- SLT-2 blood concentration

## Potential Corroborative Outcomes

- Important to use endpoints that are sensitive to treatment effect and are clinically meaningful
- e.g. HUS is clinically meaningful, but not practical
- e.g. Frequency and quantity of stool is practical, but not clinically meaningful for a drug intended to prevent HUS
- Composite outcome measures may not improve the sensitivity to treatment effects
- May introduce more noise
- May be difficult to interpret

## The best approach is one that integrates datasets from animal and human studies that provide evidence of efficacy

## Blending Animal and Human Data for Labeling 

-  Patient population to treat
-  Timing of treatment
-  Dose regimen
-  Dose
** **Clinical benefit
-  Potential risks

- Blending Animal and Human Data for Labeling

## Patient Population 

- Pediatric patients with watery or bloody diarrhea and O157-positive or SLT-positive stool sample** **

- Patient Population

**Notes:**
What is the meaning of “SLT-2-positive (slowest test)”?
Please search publication(s) of SLT-1, SLT-2, and SLT-1/2 ratio in US.
We should justify administration of TMA-15 in the case of “SLT” diagnosis.

## Prevention of STEC-Induced HUS

** **Patient population
-  **Timing of treatment**
-  Dose
-  Dose regimen
-  Clinical benefit
-  Potential risks

## Timing of Treatment

- 	Based on the animal and human data, treatment should begin immediately after confirming STEC-infection

## Prevention of STEC-Induced HUS

-  Patient population
-  Timing of treatment
-  **Dose**
** ****Dose regimen**
-  Clinical benefit
-  Potential risks

## Drug Dose and Regimen

- 	In pediatric patients, use a dose regimen that maintains the effective concentration determined preclinically
- 	Effective concentration should be maintained for the appropriate period of time determined clinically (~10 days)
- 	TMA-15 is protective in culture and *in vivo *at 10 μg/mL, which can be achieved and maintained in pediatric patients for >3 weeks with a single 3 mg/kg administration

**Notes:**
What is the difference between “The dose regimen” and “The dose”?

## Prevention of STEC-Induced HUS

-  Patient population to treat
-  Timing of treatment
-  Dose regimen
-  Dose
-  **Clinical benefit**
** **Potential risks

## Clinical Benefit

- 	Blending animal and human data should provide evidence of the desired benefit (prevention of HUS)
- 	TMA-15 animal data are statistically significant and highly predictive; clinical data suggest that the drug has the expected benefit

## Prevention of STEC-Induced HUS

-  Patient population to treat
-  Timing of treatment
-  Dose regimen
-  Dose
** **Clinical benefit
-  **Potential risks**

## Potential Risks

- 	The safety profile utilizes a combination of studies in animal models, healthy volunteers, and infected pediatric patients
- 	No safety issues have been identified for TMA-15 in animals or humans; human safety database  >107 to date

## Risk / Benefit of a Drug forPrevention of STEC-Induced HUS

**Low**

** **

** **

** **

** **

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- Risk

- Benefit

**Notes:**
Delete unless we can have better one.

## Conclusions

- Prevention of HUS is a serious, unmet medical need
- Traditional statistically significant clinical studies of HUS incidence are not feasible
- Blending animal data with human data can provide evidence of safety and efficacy needed for appropriate clinical use
- Follow-up collection of data post-marketing can further define efficacy and safety

## Examples of Approved Compounds with Small Human Databases

| Trade Name (Drug/ Biologic) | Indication | Type of
Therapy | Date of Approval | Safety  Database |  |
| --- | --- | --- | --- | --- | --- |
|  |  |  |  | No. Healthy Vol. | No. Patients |
| BabyBIG®
(Biologic) | Treatment of Infant Botulism (age 1 year or less) | IV- Ig | 10/23/03 | 0 | 422 |
| CrofabTM
(Biologic) | Treatment of  envenomation by North American pit vipers | IV- Venom specific Fab fragment of Ig- | 10/11/00 | 0 | 42 |
| CyanoKit®
(Drug) | Treatment of cyanide poisoning | Injection | 12/15/06
(Animal Rule) | 136 | 69 |
| DigifabTM
(Biologic) | Treatment of Digoxin toxicity and overdose | IV- Digoxin immune Fab | 8/31/01 | 6 | 15 |
| NovoSeven®
(Biologic) | Treatment of bleeding episodes in hemophilia | Recombinant Coagulation Factor VIIa | 3/24/99 | 0 | 93 |