📚 Part of the TILA-278 Regulatory Dossier — Reader's Guide. This article shows the live document; edits to the source appear here automatically.

---

Pre-IND Briefing Book (TILA-278)

Document ID: MTG-PreIND
Version: 1.0
Change History: 1.0 — Initial issue.
Standard(s): FDA meetings

Pre-IND Meeting Briefing Book — TILA-278

Briefing package for the Pre-IND interaction on TILA-278 in Ulcerative Colitis (moderate-to-severe): development rationale, the nonclinical package supporting first-in-human dosing, the proposed clinical starting dose and Phase 1 design, and the specific questions for the Agency. FDA meeting guidance.

1. Administrative Information and Meeting Objectives

Virtual Biopharma Inc. (the Sponsor) requests a Pre-IND (Type B) meeting to obtain the Agency's advice on the nonclinical, chemistry-manufacturing-and-controls (CMC), and clinical elements that will support first administration of TILA-278 to humans and the initiation of a United States Investigational New Drug (IND) application. TILA-278 is intended for the treatment of adults with moderate-to-severe ulcerative colitis (UC), and the Sponsor's development objective is to establish induction and maintenance of remission, with the intended marketing application to be a Biologics License Application (BLA) submitted under Section 351(a) of the Public Health Service Act and reviewed under 21 CFR Part 601.

Product and program identification

Item	Description
Sponsor	Virtual Biopharma Inc.
Investigational product	TILA-278
Modality	Recombinant humanized IgG1 bispecific monoclonal antibody (anti-TL1A antagonist arm × IL-22R agonist arm)
Approximate molecular weight	~148 kDa
Expression system	Chinese hamster ovary (CHO) cell line, fed-batch cell culture
Route of administration	Subcutaneous (SC)
Proposed indication	Induction of remission in moderate-to-severe ulcerative colitis
Intended marketing application	BLA (21 CFR Part 601)
Prior US IND	None; no prior FDA regulatory actions (e.g., clinical holds) concerning this molecule

Meeting objectives. The Sponsor seeks Agency concurrence that (i) the nonclinical pharmacology, safety pharmacology, and toxicology package is adequate to support the proposed first-in-human (FIH) study; (ii) the minimum anticipated biological effect level (MABEL)-based starting dose and the dose-escalation and stopping rules are acceptable for a molecule bearing an agonist arm; (iii) the phase-appropriate CMC control strategy assures the quality and safety of clinical supplies; and (iv) the proposed Phase 1 design and overall clinical development plan are appropriate to advance toward registration. The specific questions are consolidated in Section 8, each accompanied by the Sponsor's position.

Proposed format and attendees. A written-response-only outcome is acceptable to the Sponsor; alternatively, a teleconference/face-to-face meeting is requested. Anticipated Sponsor attendees include Regulatory Affairs, Nonclinical Safety, Clinical Pharmacology, Clinical Development (Gastroenterology), CMC/Quality, and Biostatistics.

2. Product Description and Mechanism of Action

TILA-278 is a recombinant humanized IgG1 bispecific monoclonal antibody that co-localizes two functionally distinct, mechanistically complementary binding activities on a single IgG1 framework:

• Anti-TL1A (TNFSF15) antagonist arm — neutralizes TL1A signaling through death receptor 3 (DR3/TNFRSF25), attenuating the TL1A-driven co-stimulation that amplifies TH1/TH17 effector responses and the pro-fibrotic cascade that perpetuates intestinal injury. This arm is intended to be anti-inflammatory and anti-fibrotic.
• IL-22 receptor (IL-22R) agonist arm — engages and activates the IL-22RA1 chain of the heterodimeric IL-22 receptor on intestinal epithelium, driving STAT3-dependent expression of antimicrobial peptides, mucins, and tight-junction components. This arm is intended to promote epithelial regeneration and mucosal-barrier repair (mucosal healing).

The therapeutic hypothesis is that simultaneous suppression of the inflammatory/fibrotic drive (TL1A antagonism) and active promotion of epithelial restitution (IL-22R agonism) will yield deeper and more durable disease control than agents that act on inflammation alone. This dual anti-inflammatory plus mucosal-restorative design aligns directly with the contemporary UC treatment goal of combined clinical and endoscopic/mucosal remission. TILA-278 is administered subcutaneously and is presented as a sterile aqueous solution intended for a single-use prefilled syringe/autoinjector suitable for in-clinic and, ultimately, at-home administration.

3. Development Rationale and Unmet Medical Need

Ulcerative colitis is a chronic, relapsing-remitting inflammatory bowel disease characterized by mucosal inflammation of the colon with symptoms of rectal bleeding, urgency, and increased stool frequency, and by structural bowel damage over time. Despite conventional therapies (5-aminosalicylates, corticosteroids, immunomodulators) and the introduction of biologic and targeted synthetic agents (anti-TNF, anti-integrin, anti-IL-23/IL-12/23, and JAK inhibitors), a substantial proportion of patients with moderate-to-severe disease fail to achieve — or lose — clinical and endoscopic remission, and mucosal healing remains an incompletely met treatment target that predicts durable outcomes.

Human genetics and translational biology implicate the TL1A–DR3 axis as a driver of intestinal inflammation and fibrosis in inflammatory bowel disease, providing the rationale for the antagonist arm. In parallel, IL-22 is a key epithelial-protective cytokine that promotes mucosal regeneration and barrier integrity, providing the rationale for the agonist arm. Existing agents predominantly interrupt inflammatory signaling but do not actively drive epithelial repair. By combining TL1A antagonism with IL-22R agonism in a single molecule, TILA-278 is designed to address both the inflammatory driver and the restorative deficit within one therapeutic, differentiating it mechanistically from currently available treatments and supporting the unmet need for deeper remission in moderate-to-severe UC.

4. Summary of the Nonclinical Program Supporting First-in-Human Dosing

The nonclinical program was designed in accordance with ICH S6(R1) (preclinical safety evaluation of biotechnology-derived pharmaceuticals), with study timing relative to clinical development guided by ICH M3(R2), reproductive assessment per ICH S5(R3), and safety pharmacology per ICH S7A. The package described below is intended to support the proposed Phase 1 SAD/MAD study; longer-duration and reproductive studies to support later development are identified as ongoing or planned.

4.1 Species-Relevance Strategy

TILA-278 is engineered against human targets and is human-target-specific; neither arm recognizes rodent orthologues with functionally meaningful affinity, so conventional rodents are not pharmacologically relevant for the pharmacology or toxicology of the clinical molecule. Consistent with ICH S6(R1):

• The cynomolgus monkey is the single pharmacologically relevant species and the sole species used for repeat-dose toxicology, toxicokinetics, and integrated safety pharmacology. Both arms cross-react with the cynomolgus orthologues of TL1A and IL-22RA1 with affinity and functional potency within approximately 2- to 3-fold of the human targets, and functional agonism/antagonism at the cynomolgus targets was confirmed in vitro.
• In vivo disease pharmacology, which cannot be studied with the clinical molecule in rodents, was generated with a homologous murine surrogate bispecific antibody in established mouse colitis models.
• Tissue cross-reactivity (TCR) studies on full human and cynomolgus tissue panels for both specificities confirmed binding restricted to expected target-expressing tissues and bridge the toxicology species to humans.

4.2 Primary Pharmacodynamics

The anti-TL1A arm binds human TL1A with high affinity (K_D ≈ 0.2 nM) and neutralizes TL1A–DR3 signaling with an IC₅₀ of approximately 0.3 nM in a cell-based reporter assay. The IL-22R agonist arm binds human IL-22RA1 and functions as an agonist, inducing STAT3 phosphorylation with an EC₅₀ of approximately 0.5 nM in an epithelial reporter system and driving antimicrobial-peptide, mucin, and tight-junction gene expression in primary human intestinal epithelial cells. A bridging assay confirmed that a single molecule can engage TL1A and IL-22RA1 simultaneously. In the murine surrogate colitis models, the dual-active molecule reduced colonic histopathology, lowered IL-17/IFN-γ, increased epithelial regeneration markers, and improved barrier integrity, and produced greater mucosal healing than either single activity alone at matched exposure — supporting the complementary dual-mechanism hypothesis.

4.3 Safety Pharmacology

Safety pharmacology endpoints (cardiovascular by telemetry including ECG/QTc, respiratory, and CNS/neurobehavioral) were integrated into the repeat-dose cynomolgus program per ICH S6(R1) and showed no adverse effects up to the highest dose tested. Because one arm is an agonist and the molecule is immunomodulatory, an in vitro cytokine-release assay using human whole blood and peripheral blood mononuclear cells was performed under soluble and immobilized conditions; no meaningful pro-inflammatory cytokine induction was observed, indicating a low cytokine-release risk that supports the FIH starting-dose rationale. As a large protein that does not interact with cardiac ion channels, TILA-278 has no expected hERG liability, and hERG testing was not performed; a dedicated thorough QT study was not conducted, consistent with the ICH E14/S7B (and E14/S7B Q&A) waiver rationale for a biologic with no plausible direct electrophysiological mechanism and negative integrated cardiovascular telemetry.

4.4 Nonclinical Pharmacokinetics, Toxicokinetics, and Immunogenicity

Following SC administration in the cynomolgus monkey, TILA-278 showed pharmacokinetics typical of a humanized IgG1: absolute bioavailability of approximately 65–75%, low steady-state volume of distribution (≈ 60–80 mL/kg), a terminal half-life of approximately 10–14 days, and modest accumulation (≈ 2–3-fold) with weekly dosing. Systemic exposure was nonlinear (more-than-dose-proportional) at low doses where target-mediated drug disposition (TMDD) predominates and became approximately dose-proportional at higher doses where the TMDD pathway is saturated. Elimination is by catabolism to peptides and amino acids; TILA-278 is not a CYP substrate and is not eliminated intact renally. Anti-drug antibodies (ADA) were detected in a proportion of dosed animals (≈ 20–40% incidence), as expected when a humanized antibody is administered to a non-human species; ADA reduced exposure in a subset but did not preclude maintenance of adequate, interpretable exposure at the top doses. As an IgG1, TILA-278 is expected to undergo FcRn-mediated placental transfer, relevant to the reproductive risk assessment.

4.5 Toxicology

First-in-human dosing is supported by a completed GLP 4-week repeat-dose SC toxicity study in the cynomolgus monkey (with integrated safety pharmacology and an 8-week recovery phase) at doses of approximately 10, 30, and 100 mg/kg administered once weekly. TILA-278 was well tolerated; findings were limited to minimal, reversible injection-site reactions and to reversible pharmacodynamic shifts in circulating T-cell subsets consistent with TL1A antagonism, without functional immunodeficiency. Given the IL-22R agonist activity, IL-22RA1-expressing epithelial tissues (gastrointestinal tract, skin, liver, pancreas, kidney, lung) were examined for hyperplasia or dysplasia; none was observed at any dose. The no-observed-adverse-effect level (NOAEL) was the highest dose tested (≈ 100 mg/kg/week). A pivotal 26-week chronic SC toxicity study (with a 12-week recovery phase) and an enhanced pre- and postnatal development (ePPND) study in the cynomolgus monkey are planned/ongoing to support longer-duration dosing and the intended population, consistent with ICH M3(R2) and S5(R3).

Consistent with ICH S6(R1), genotoxicity and carcinogenicity studies are not scientifically warranted for a monoclonal antibody composed of natural amino acids and were not conducted; carcinogenic potential is addressed by a weight-of-evidence assessment (no epithelial hyperplasia/dysplasia at any dose; reversible, partial immunomodulation; time-limited induction use). Malignancy and serious/opportunistic infection are carried as monitored risks in the clinical program.

Table 4-1. Overview of the Nonclinical Program Supporting First-in-Human Dosing

Domain	Study type	Test system	Route	GLP	Status
Primary PD (in vitro)	Binding, TL1A neutralization, IL-22R agonism, dual engagement, selectivity	Human & cynomolgus proteins/cells; primary human intestinal epithelial cells	—	Non-GLP	Complete
Primary PD (in vivo)	Colitis models with murine surrogate	Mouse (adoptive T-cell transfer, DSS)	IP/SC	Non-GLP	Complete
Secondary PD	Tissue cross-reactivity (both arms)	Human & cynomolgus tissue panels	—	GLP	Complete
Safety pharmacology	Cardiovascular/respiratory/CNS (integrated); in vitro cytokine-release assay	Cynomolgus; human whole blood/PBMC	SC / —	GLP / Non-GLP	Complete
PK / TK	SC pharmacokinetics, TMDD, ADA impact	Cynomolgus	SC	Non-GLP / GLP	Complete
Repeat-dose toxicity (FIH-enabling)	4-week, with recovery	Cynomolgus	SC	GLP	Complete
Repeat-dose toxicity (chronic)	26-week, with recovery	Cynomolgus	SC	GLP	Planned/ongoing
Reproductive/developmental	ePPND (+ surrogate fertility/EFD as needed)	Cynomolgus (+ mouse surrogate)	SC	GLP	Planned
Genotoxicity / carcinogenicity	Not conducted (scientifically unwarranted)	—	—	—	Not applicable

5. Chemistry, Manufacturing, and Controls (CMC) Status

TILA-278 drug substance is a recombinant humanized IgG1 bispecific monoclonal antibody expressed in a CHO cell line by fed-batch cell culture and purified by Protein-A affinity capture followed by orthogonal polishing chromatography (e.g., cation- and anion-exchange). Viral safety is assured by a two-tier strategy — dedicated clearance steps (low-pH viral inactivation and viral-retentive nanofiltration) plus raw-material and cell-bank virus testing — in accordance with ICH Q5A(R2). Stability is being established under ICH Q5C conditions, and the specification is set consistent with ICH Q6B.

The control strategy is phase-appropriate and includes identity (peptide mapping, intact/reduced mass by LC-MS, confirmation of the bispecific pairing/assembly), purity and product-related variants (aggregates by SEC, fragments by CE-SDS, charge variants by icIEF), Fc N-glycan profiling, and process/safety-related impurities (host-cell protein, residual DNA, residual Protein A, endotoxin/bioburden). Biological activity is controlled by a dual, arm-specific potency strategy: an anti-TL1A neutralization cell-based assay and an IL-22R agonism reporter/functional assay, each with defined acceptance criteria. The drug product is a sterile SC solution at a nominal concentration of 150 mg/mL in a histidine buffer (pH ~5.8) with polysorbate and a stabilizing sugar, presented in a single-use prefilled syringe/autoinjector. Manufacturing and control are conducted under cGMP; comparability will be maintained across process changes per ICH Q5E. The CMC package is adequate to assure the identity, purity, potency, and safety of clinical supplies for the proposed Phase 1 study.

6. Proposed First-in-Human Starting Dose and Escalation Strategy

Because TILA-278 contains an agonist arm and is immunomodulatory, the FIH starting dose was selected using a minimum anticipated biological effect level (MABEL) approach rather than a NOAEL/allometric-scaling approach alone, consistent with the EMA guideline on first-in-human and early clinical trials (EMA/CHMP/SWP/28367/07 Rev. 1) and applicable FDA guidance. The MABEL was derived by integrating (i) the in vitro functional potency of both arms — with the IL-22R agonist arm (EC₅₀ ≈ 0.5 nM) taken as the more conservative, pharmacology-driving determinant — (ii) target-receptor occupancy modeling, and (iii) the negative in vitro cytokine-release assessment. The starting dose was set to produce systemic exposure yielding minimal (low single-digit percent) predicted receptor occupancy and pharmacodynamic effect, providing a substantial safety multiple below both the pharmacologically active exposure and the exposure at the cynomolgus NOAEL (≈ 100 mg/kg/week), at which the general-toxicology AUC margin over the anticipated maximum clinical exposure is approximately 20-fold.

Dose escalation will proceed through pre-defined cohorts with sentinel dosing (initial administration to a small number of subjects per cohort with a defined observation interval before dosing the remainder), conservative fixed or PK/PD-model-guided escalation increments, protocol-specified stopping and dose-modification rules, and staggered progression governed by emerging safety, PK, and pharmacodynamic data reviewed by an independent safety monitoring function. The maximum planned exposure will remain within the boundary established by the nonclinical NOAEL and its safety margin.

7. Proposed Clinical Development Plan and Phase 1 Study Design

7.1 Overall Clinical Development Plan

The Sponsor's plan is a stepwise program: (1) a Phase 1 single-ascending-dose (SAD) and multiple-ascending-dose (MAD) study to establish FIH safety, tolerability, SC pharmacokinetics, immunogenicity, and early pharmacodynamics; (2) a Phase 2b, randomized, double-blind, placebo-controlled induction study in moderate-to-severe UC (Study TILA278-201) to establish efficacy on clinical remission and endoscopic endpoints and to select the dose(s) for registration; and (3) confirmatory pivotal induction and maintenance studies to support the intended BLA under 21 CFR Part 601. Clinical pharmacology (population PK, exposure–response, immunogenicity impact) and the pediatric plan (initial pediatric study plan/PSP) will be developed in parallel with the interactions and timing to be discussed with the Agency.

7.2 Phase 1 SAD Design

The FIH study is a randomized, double-blind, placebo-controlled SAD evaluation in healthy adult participants (with the option to include a UC patient cohort at pharmacologically active dose levels). Each SAD cohort comprises approximately 8 participants randomized 3:1 (active:placebo) with sentinel dosing of the first participants. TILA-278 is administered as a single SC injection with ascending doses across cohorts beginning at the MABEL-based starting dose (Section 6). Endpoints include safety and tolerability (adverse events, injection-site reactions, clinical laboratory, vital signs, ECG), SC pharmacokinetics (with characterization of TMDD-driven nonlinearity), and immunogenicity (ADA by a validated tiered assay: screening → confirmatory → titer, with neutralizing-antibody characterization).

7.3 Phase 1 MAD Design

The MAD portion evaluates repeat SC dosing over several weeks in cohorts of approximately 8 participants each (randomized active:placebo, with sentinel dosing), at dose levels informed by the SAD results and bracketing the anticipated therapeutic range. Endpoints add characterization of PK accumulation and dose proportionality at steady state, early target-engagement and disease-relevant pharmacodynamic biomarkers (e.g., C-reactive protein and fecal calprotectin in a patient cohort), and repeat-dose immunogenicity. The MAD data will inform the regimen for the planned Phase 2b induction study.

7.4 Planned Phase 2b Induction Study (TILA278-201) — Design Framework

To orient the Agency to the intended registration pathway, the planned Phase 2b induction study is a randomized, double-blind, placebo-controlled, parallel-group study with 1:1:1 allocation to TILA-278 High dose, TILA-278 Low dose, and matching placebo (SC), with a 12-week induction period and a target of approximately 900 randomized adults with moderate-to-severe UC, stratified by baseline modified Mayo severity and prior biologic exposure. The proposed primary endpoint is clinical remission at Week 12, defined as a modified Mayo score ≤ 2 with no individual subscore > 1; key secondary endpoints include change from baseline in modified Mayo score and endoscopic improvement/mucosal healing (centrally read). The endpoint framework, estimand strategy, and dose selection will be refined and discussed at subsequent milestone interactions (e.g., End-of-Phase-2).

8. Specific Questions for the Agency

For each question, the Sponsor's position and rationale are provided.

1. Nonclinical adequacy for FIH. Does the Agency agree that the nonclinical package — in vitro dual-mechanism pharmacology, the homologous-surrogate in vivo pharmacology, tissue cross-reactivity, integrated safety pharmacology with an in vitro cytokine-release assay, nonclinical PK/TK, and the GLP 4-week repeat-dose SC cynomolgus toxicity study (NOAEL at the highest dose, ≈ 100 mg/kg/week) — is adequate to support the proposed Phase 1 SAD/MAD study? Sponsor position: Yes. The cynomolgus monkey is the sole pharmacologically relevant species, and the completed package characterizes the intended pharmacology and defines an adequate safety margin; longer-duration and reproductive studies are planned to support later phases per ICH M3(R2)/S6(R1)/S5(R3).

2. Starting-dose and escalation strategy. Does the Agency concur with the MABEL-based starting dose and with the proposed sentinel dosing, escalation increments, staggering, and stopping/dose-modification rules for a molecule bearing an agonist arm? Sponsor position: Yes. MABEL is the appropriate basis given the IL-22R agonist activity, with substantial multiples below the pharmacologically active and NOAEL exposures and a negative in vitro cytokine-release assessment.

3. Studies not warranted. Does the Agency agree that genotoxicity, carcinogenicity (standard rodent bioassays), hERG assessment, and a dedicated thorough QT study are not scientifically warranted for this monoclonal antibody, consistent with ICH S6(R1), S1, S2(R1), and E14/S7B (and the E14/S7B Q&A)? Sponsor position: Yes. TILA-278 cannot interact directly with DNA or cardiac ion channels; carcinogenic potential is addressed by weight-of-evidence, and cardiovascular safety by integrated cynomolgus telemetry and clinical ECG monitoring.

4. CMC control strategy. Does the Agency agree that the phase-appropriate CMC package — CHO expression, Protein-A capture plus orthogonal polishing, viral safety per ICH Q5A(R2), stability per ICH Q5C, specifications per ICH Q6B, and the dual arm-specific potency strategy — is acceptable to support the proposed Phase 1 study? Sponsor position: Yes. The control strategy assures identity, purity, potency, and safety of clinical supplies and controls the product-related variants relevant to a bispecific IgG1.

5. Immunogenicity strategy. Does the Agency agree with the proposed tiered ADA assay strategy (screening → confirmatory → titer, with neutralizing-antibody characterization) and the evaluation of ADA impact on PK, efficacy, and safety? Sponsor position: Yes, consistent with current immunogenicity assessment expectations for therapeutic proteins.

6. Phase 1 design. Does the Agency agree that the proposed Phase 1 SAD/MAD design (population, cohort size, sentinel dosing, PK/PD/ADA sampling, and safety monitoring) is acceptable? Sponsor position: Yes.

7. Overall development plan. Does the Agency agree that the overall clinical development plan — advancing from Phase 1 to a Phase 2b induction study (TILA278-201) with Week-12 clinical remission by modified Mayo as the primary endpoint, toward confirmatory induction and maintenance studies — is an appropriate basis to support the intended BLA under 21 CFR Part 601? Sponsor position: Yes; endpoint, estimand, and dose-selection details will be finalized at subsequent milestone interactions.

8. Pediatric plan. Does the Agency agree with the proposed timing for submission of the initial pediatric study plan (iPSP) relative to the development milestones described above? Sponsor position: The Sponsor proposes to submit the iPSP in accordance with the applicable timing and requests confirmation.

9. References and Appendices

1. ICH Harmonised Tripartite Guideline S6(R1). Preclinical Safety Evaluation of Biotechnology-Derived Pharmaceuticals. 2011.
2. ICH Harmonised Tripartite Guideline M3(R2). Guidance on Nonclinical Safety Studies for the Conduct of Human Clinical Trials and Marketing Authorization for Pharmaceuticals. 2009.
3. ICH Harmonised Guideline S5(R3). Detection of Reproductive and Developmental Toxicity for Human Pharmaceuticals. 2020.
4. ICH Harmonised Tripartite Guideline S7A. Safety Pharmacology Studies for Human Pharmaceuticals. 2000.
5. ICH Guidelines S7B and E14, and the E14/S7B Implementation Working Group Questions & Answers. 2005; Q&A 2022.
6. ICH Harmonised Guideline Q5A(R2) (Viral Safety), Q5C (Stability of Biotechnological/Biological Products), Q5E (Comparability), and Q6B (Specifications).
7. European Medicines Agency. Guideline on Strategies to Identify and Mitigate Risks for First-in-Human and Early Clinical Trials with Investigational Medicinal Products (EMA/CHMP/SWP/28367/07 Rev. 1). 2017.
8. Literature on the TL1A (TNFSF15)–DR3 axis in inflammatory bowel disease and intestinal fibrosis, and on IL-22-mediated epithelial regeneration and mucosal-barrier repair, supporting the dual-mechanism rationale for TILA-278.

Appendices (provided under separate cover): proposed Phase 1 clinical protocol synopsis; Investigator's Brochure; nonclinical study reports and tabulated summaries (CTD Module 4 / Module 2.6); CMC summary (CTD Module 3 / Module 2.3). Cross-references to the corresponding CTD modules are maintained in the application index.