DV-02 — Vaccine Construct Engineering Package

PROJECT HELIX-HTT | Huntington’s-Adjacent Neuro-Oncology Vaccine Program

DOCUMENT CONTROL HEADER

Program: PROJECT HELIX-HTT

Phase: II — Preclinical Vaccine Development

Module: 2 — Vaccine Construct Engineering

Document Code: SCF-DV02-VCEP-NO-0001

Purpose: Engineer and optimize vaccine constructs using the Validated Antigen Master Inventory (VAMI).

1. EXECUTIVE SUMMARY

The Vaccine Construct Engineering Package converts validated antigens into manufacturable vaccine products.

This module determines:

• Vaccine platform
• Antigen architecture
• Antigen ordering
• Delivery strategy
• Immune amplification strategy
• Manufacturability
• Scalability

2. CONSTRUCT ENGINEERING OBJECTIVES

Primary Objectives:

✓ Maximize antigen presentation

✓ Maximize CD8 activation

✓ Maximize CD4 support

✓ Minimize immune escape

✓ Maintain CNS safety

✓ Enable scalable manufacturing

3. PLATFORM SELECTION ANALYSIS

Platform A

Multi-Antigen mRNA Vaccine

Advantages:

• Rapid manufacturing
• Personalized design
• Multi-antigen loading
• Flexible reformulation

SCF Score:

★★★★★

Recommended:

Primary Platform

Platform B

Synthetic Long Peptide (SLP)

Advantages:

• Stability
• Simpler manufacturing
• Regulatory familiarity

SCF Score:

★★★★☆

Recommended:

Backup Platform

Platform C

Dendritic Cell Vaccine

Advantages:

• Personalized
• Strong immune activation

Limitations:

• Complex manufacturing
• Expensive

SCF Score:

★★★☆☆

Recommended:

Advanced/Refractory Program

4. REFERENCE CONSTRUCT ARCHITECTURE

HELIX-VAX-01

First Generation Construct

Composition:

Neoantigen A1
↓
Linker
↓
Neoantigen A2
↓
Linker
↓
Fusion Antigen F1
↓
Linker
↓
Neoantigen A3
↓
Linker
↓
TAA B1

Purpose:

• Broad coverage
• Multiple HLA presentations
• Reduced escape

5. ANTIGEN SELECTION FRAMEWORK

Primary Construct

Target:

8–12 antigens

Composition:

Backup Construct

Target:

5–8 antigens

Used for:

• Escape mitigation
• Manufacturing redundancy

6. MULTI-CONSTRUCT STRATEGY

Construct A

Primary Vaccine

Focus:

Highest-ranked antigens

Construct B

Escape Prevention Construct

Focus:

Subclonal antigens

Construct C

SCF Experimental Construct

Focus:

Stress antigens

Research Use Only

7. ANTIGEN ORDERING ALGORITHM

Design Principles

Place:

1. Highest-expression antigens first
2. Strongest-presented antigens next
3. Broadest HLA coverage next
4. Lower abundance antigens later

Priority Hierarchy

Clonal Neoantigen
↓
Fusion Antigen
↓
Secondary Neoantigen
↓
TAA
↓
Exploratory Antigen

8. LINKER ENGINEERING STRATEGY

Purpose

Separate antigens.

Benefits:

• Improved processing
• Reduced junction artifacts
• Enhanced presentation

Linker Requirements

✓ Flexible

✓ Non-immunogenic

✓ Efficient cleavage

9. IMMUNE ACTIVATION ENGINEERING

CD8 Activation Layer

Objective:

Maximize cytotoxic T-cell activation.

Design Factors:

• HLA-I compatibility
• Proteasomal processing
• Presentation efficiency

CD4 Activation Layer

Objective:

Support durable immunity.

Design Factors:

• HLA-II coverage
• Memory formation

10. IMMUNE ESCAPE PREVENTION DESIGN

Strategy 1

Multi-Antigen Coverage

Strategy 2

Clonal Target Preference

Strategy 3

Fusion Antigen Inclusion

Strategy 4

Backup Antigen Library

11. SCF MICROENVIRONMENT INTEGRATION

Construct engineering incorporates:

MES Findings

12. CNS SAFETY ARCHITECTURE

Mandatory Filters

Exclude:

✗ Neuronal self-antigens

✗ Essential CNS proteins

✗ High neuroinflammatory risk antigens

Safety Goal

Maintain:

CNS Compatibility Index (CCI)

Above threshold

13. MANUFACTURABILITY ASSESSMENT

Evaluation Criteria

14. PLATFORM-SPECIFIC CMC CONSIDERATIONS

mRNA Platform

Requirements:

• Sequence integrity
• Encapsulation validation
• Potency testing

SLP Platform

Requirements:

• Peptide purity
• Peptide identity
• Stability testing

15. CONSTRUCT QUALITY ATTRIBUTES

Critical Quality Attributes (CQAs)

Identity

Correct antigen sequence

Purity

Minimal contaminants

Potency

Immune activation capability

Stability

Storage durability

16. CONSTRUCT SUCCESS METRICS

Construct Potency Score (CPS)

Measures:

• Antigen quality
• Presentation efficiency

Escape Resistance Score (ERS)

Measures:

• Resistance to antigen loss

CNS Compatibility Score (CCS)

Measures:

• Neuroimmune safety

17. FINAL CONSTRUCT RECOMMENDATION

Lead Development Candidate

HELIX-VAX-01

Platform:

Multi-Antigen mRNA

Composition:

• 8–12 validated antigens
• Neoantigen dominant
• Fusion supported
• TAA augmented

Development Status:

Advance

Backup Candidate

HELIX-VAX-02

Platform:

Synthetic Long Peptide

Development Status:

Advance in parallel

18. OUTPUT FILES

DV02-01

Construct Design Blueprint

DV02-02

Antigen Ordering Map

DV02-03

Linker Architecture Plan

DV02-04

Manufacturing Readiness Assessment

DV02-05

CNS Safety Engineering Report

DV02-06

Lead Construct Recommendation

DECISION GATE

Advance to DV-03 Adjuvant Selection Package if:

✓ Construct architecture finalized

✓ Antigen composition approved

✓ CNS safety review complete

✓ Manufacturability acceptable

✓ Lead construct selected

STATUS

DV-02 — Vaccine Construct Engineering Package: COMPLETE

NEXT DELIVERABLE

DV-03 — Adjuvant Selection & Optimization Package

This module will build the complete immune amplification architecture for HELIX-VAX-01 and HELIX-VAX-02, including dendritic-cell activation strategy, innate immune priming logic, neuroimmune safety controls, and SCF microenvironment-conditioned adjuvant selection.