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Module 2.7.1 — Summary of Biopharmaceutic Studies (TILA-278)

Field	Value
Document ID	M2.7.1
Version	1.0
Compound	TILA-278 (anti-TL1A antagonist / IL-22R agonist bispecific)
Standard	ICH M4E / E3
Confidentiality	Confidential

CTD summary for the TILA-278 program; clinical figures trace to Study TILA278-201.

Change History

Version	Date	Author	Summary
1.0	2026-07-08	Clinical/Regulatory	Initial issue

2.7.1 Summary of Biopharmaceutic Studies and Associated Analytical Methods

2.7.1.1 Background and Overview

2.7.1.1.1 Scope and Applicability of the Biopharmaceutics Program

TILA-278 is a recombinant humanized IgG1 bispecific monoclonal antibody in development by Virtual Biopharma Inc. for the treatment of moderate-to-severe ulcerative colitis (UC). One antigen-binding arm is an antagonist of TL1A (TNFSF15) and the second is an agonist of the interleukin-22 receptor (IL-22R), providing complementary suppression of TH1/TH17-driven inflammation and intestinal fibrosis together with epithelial regeneration and mucosal-barrier repair. TILA-278 is administered exclusively by subcutaneous (SC) injection as a sterile aqueous solution; there is no oral presentation and no marketed intravenous (IV) presentation.

Because TILA-278 is a large (~150 kDa) parenterally administered protein therapeutic, the classical biopharmaceutic assessments developed for orally administered small-molecule solid dosage forms are not scientifically applicable and were not conducted. Specifically, the following elements are not applicable to this program, and their absence is by design rather than by omission:

• Absolute oral bioavailability — not applicable; TILA-278 is not administered by the oral route. As an antibody it would be proteolytically degraded in the gastrointestinal tract and is not absorbed intact orally.
• Food-effect studies — not applicable; there is no oral or enterally absorbed formulation for which prandial state could modify absorption.
• In vitro dissolution / disintegration and dissolution-based in vitro–in vivo correlation (IVIVC) — not applicable; the drug product is a ready-to-use solution rather than a solid oral dosage form. Compendial dissolution methodology has no meaning for a solution presented for SC injection.
• Gastrointestinal pH / transit / regional-absorption considerations — not applicable for the SC route.

The biopharmaceutics program for TILA-278 therefore concentrates on the assessments that are meaningful for an SC-administered biologic and that support the to-be-marketed presentation:

1. Validation and performance characterization of the bioanalytical methods used to generate the pharmacokinetic (PK) and immunogenicity data supporting the program, with explicit attention to the interference of anti-drug antibodies (ADA) and circulating target on the drug-concentration assay (an "ADA-aware", drug-tolerant PK method).
2. Determination of the absolute SC bioavailability and characterization of the absorption profile of TILA-278 following SC administration, using an IV reference.
3. Formulation and delivery-device bridging between the prefilled syringe (PFS) and the single-use autoinjector (AI) presentations intended for commercialization.

This summary should be read together with the Clinical Pharmacology written summary (Module 2.7.2), the nonclinical pharmacokinetics written summary (Module 2.6.4/2.6.5), the drug-product quality documentation (Module 3.2.P), and the individual bioanalytical and clinical study reports (Modules 5.3.1, 5.3.3, and 5.3.5). It has been prepared in accordance with ICH M4E(R2) and reflects the organization set out for CTD Section 2.7.1. Bioanalytical methods were validated in accordance with ICH M10 (Bioanalytical Method Validation and Study Sample Analysis); the immunogenicity strategy follows a tiered approach consistent with prevailing regulatory guidance for therapeutic protein immunogenicity.

2.7.1.1.2 Drug Product Presentations

The TILA-278 drug product is a sterile, preservative-free aqueous solution for SC injection. It is formulated in an aqueous buffer with polysorbate as surfactant and is supplied at a nominal protein concentration of 150 mg/mL. Two functionally equivalent single-use presentations are used across the program and are intended for marketing:

• a prefilled syringe (PFS) delivering a nominal 1.0 mL injection; and
• a disposable autoinjector (AI) incorporating the same primary container/closure and delivering the same nominal volume.

Both presentations share identical formulation composition, fill volume, and primary container contact materials; they differ only in the injection-assist device. The clinical formulation used throughout the Phase 2b induction study (Protocol TILA278-201) and the commercial formulation are qualitatively and quantitatively identical; no post-Phase 2b formulation change requiring a comparative bioavailability bridge has been introduced. Full compositional and comparability information is provided in Module 3.2.P.

2.7.1.1.3 Overview of Studies Contributing to the Biopharmaceutics Assessment

The studies and reports contributing to this section are summarized in Table 2.7.1-1. The first-in-human study (TILA278-101) provides the pivotal absolute-bioavailability and absorption data; the device-bridging study (TILA278-102) supports interchangeability of the PFS and AI; and the bioanalytical validation reports underpin all reported PK and immunogenicity data, including those from the pivotal Phase 2b study TILA278-201.

Table 2.7.1-1. Studies and Analytical Reports Contributing to the Biopharmaceutics Summary

Study / Report	Design and objective	Population	Presentation / route	Location in CTD
TILA278-101	Phase 1 single- and multiple-ascending-dose; included an IV reference cohort for absolute SC bioavailability and absorption characterization	Healthy adults	PFS SC; IV reference	5.3.3.1
TILA278-102	Phase 1 relative-bioavailability / device-bridging; parallel-group comparison of PFS vs autoinjector	Healthy adults	PFS SC vs AI SC	5.3.1.2
TILA278-201	Phase 2b randomized, double-blind, placebo-controlled induction study; source of population-PK and immunogenicity data	Moderate-to-severe UC	PFS/AI SC	5.3.5.1
VAL-PK-278	Validation of the drug-tolerant PK (drug-concentration) ligand-binding assay	N/A	N/A	5.3.1.4
VAL-ADA-278	Validation of the tiered ADA (screen/confirm/titer) and neutralizing-antibody assays	N/A	N/A	5.3.1.4

2.7.1.2 Summary of Results of Individual Studies

2.7.1.2.1 Bioanalytical Methods

The interpretation of all PK, exposure–response, and immunogenicity analyses for TILA-278 depends on the validity of the underlying bioanalytical methods. Because TILA-278 is a bispecific antibody whose measured concentrations can be confounded by (i) the presence of soluble and membrane targets (TL1A and IL-22R shed/soluble forms) and (ii) the development of ADA, the assay strategy was designed to quantify functionally intact, bispecific drug and to be tolerant of anticipated concentrations of target and ADA. All methods were validated in serum in accordance with ICH M10.

2.7.1.2.1.1 Drug-Concentration (PK) Assay — ADA-Aware Design

The pivotal PK method (Report VAL-PK-278) is a validated ligand-binding assay in an electrochemiluminescence (ECL) bridging format. To ensure that only functionally intact bispecific antibody is measured, the assay captures TILA-278 through one binding arm (immobilized TL1A) and detects it through the other (labeled IL-22R extracellular domain). This "both-arms-engaged" design confers two advantages relevant to a bispecific: it reports the concentration of drug capable of engaging both targets, and it reduces over-reporting of monovalent fragments or single-arm-bound complexes.

The assay is ADA-aware and drug-tolerant. Acid-dissociation sample pretreatment was incorporated to liberate drug from ADA and target complexes prior to capture, and drug tolerance in the presence of a defined ADA-positive control was demonstrated across the calibration range. Selectivity/specificity experiments confirmed acceptable recovery in the presence of physiologically and pathologically relevant concentrations of soluble TL1A and soluble IL-22R. Method performance is summarized in Table 2.7.1-2.

Table 2.7.1-2. Validation Summary — TILA-278 Drug-Concentration (PK) Assay (Serum)

Parameter	Result
Platform / format	ECL bridging ligand-binding assay (TL1A capture / IL-22R detection)
Calibration range	50 – 5,000 ng/mL
Lower limit of quantitation (LLOQ)	50 ng/mL
Inter-assay precision (%CV)	≤ 12.4% across QC levels
Inter-assay accuracy (%RE)	within ± 11% of nominal
Total error	≤ 24% at all QC levels (meets ≤ 30% criterion)
Dilutional linearity / hook	Linear to at least 1:200; no high-dose hook to 1,000 µg/mL
Selectivity (normal + UC serum)	≥ 90% of individual lots within acceptance
Target interference	No significant interference at physiologic soluble TL1A / IL-22R levels
ADA (drug) tolerance	Quantitation within acceptance at high positive-control ADA titer
Benchtop / freeze–thaw / long-term stability	Established for ≥ 12 months at −70 °C

2.7.1.2.1.2 Immunogenicity Assays — Tiered Strategy

Immunogenicity was assessed using a multi-tiered strategy (Report VAL-ADA-278) comprising a screening assay, a confirmatory (competitive inhibition) assay, and a quasi-quantitative titer assay, followed by characterization of neutralizing antibodies (NAb) and, given the bispecific architecture, domain (arm) specificity of confirmed positive responses. Screening and confirmatory assays used an ECL bridging format; the NAb assay used a competitive ligand-binding format assessing interference with target engagement for each arm. Cut points (screening, confirmatory, titer) were established statistically from drug-naïve individual serum lots. Key characteristics are shown in Table 2.7.1-3.

Table 2.7.1-3. Validation Summary — TILA-278 ADA and Neutralizing-Antibody Assays

Parameter	Screening / Confirmatory ADA	Neutralizing antibody (NAb)
Format	ECL bridging	Competitive ligand-binding (per arm)
Sensitivity	24 ng/mL (positive control)	250 ng/mL
Drug tolerance (at low positive control)	Tolerant to ~25 µg/mL TILA-278	Tolerant to ~5 µg/mL TILA-278
Screening cut-point false-positive rate	~5% (target)	N/A
Confirmatory cut point	Established (1% target)	N/A
Domain specificity	Anti-TL1A-arm / anti-IL-22R-arm characterization performed	N/A

The drug tolerance of the ADA assay exceeds anticipated trough concentrations at clinical doses, supporting reliable ADA detection in the presence of circulating drug. Immunogenicity results from the pivotal study and their relationship to PK, efficacy, and safety are summarized in Module 2.7.2.

2.7.1.2.2 Absolute Subcutaneous Bioavailability and Absorption (Study TILA278-101)

Study TILA278-101 was a Phase 1, randomized, double-blind, placebo-controlled single- and multiple-ascending-dose study in healthy adults that included a dedicated IV reference cohort to permit estimation of the absolute bioavailability of the SC route. SC doses were administered via the clinical PFS presentation into the abdomen. PK samples were analyzed using the validated method described in Section 2.7.1.2.1.1.

Following single SC administration, TILA-278 exhibited slow absorption characteristic of an SC-administered IgG1 antibody, consistent with predominant uptake via the lymphatic system. Absorption was protracted, with a median time to maximum concentration (Tmax) of approximately 6 days, and elimination was slow, with a terminal half-life of approximately 18 days at doses at which target-mediated clearance was substantially saturated. The absolute SC bioavailability was approximately 64% (Table 2.7.1-4), within the expected range for a therapeutic IgG1 monoclonal antibody administered subcutaneously.

Table 2.7.1-4. Absolute SC Bioavailability and Single-Dose Absorption Parameters, Study TILA278-101

Parameter (single dose, reference dose level)	SC (PFS)	IV reference
Cmax (µg/mL), geometric mean	21.3	78.4 (end of infusion)
Tmax (days), median	6.0	N/A
AUC0–∞ (µg·day/mL), geometric mean	402	628
Terminal t½ (days), mean	18.1	19.4
Absolute bioavailability F (%), point estimate (90% CI)	64% (55–74)	—

Systemic exposure increased in a greater-than-dose-proportional manner across the ascending SC dose range, consistent with saturation of target-mediated drug disposition (TMDD) at higher concentrations. At the lowest doses, clearance was elevated and the concentration–time profile showed the curvature typical of nonlinear, target-mediated elimination; at higher doses the disposition approached linearity as target-mediated clearance became saturated. These absorption and disposition characteristics, and the supporting population-PK model, are described in detail in Module 2.7.2.

2.7.1.2.3 Formulation and Delivery-Device Bridging (Study TILA278-102)

Study TILA278-102 was a Phase 1, randomized, open-label, parallel-group relative-bioavailability study in healthy adults designed to bridge the prefilled syringe (PFS) and the autoinjector (AI) presentations. A parallel-group design was selected in preference to a crossover because the long terminal half-life of TILA-278 (18 days) would necessitate an impractically long washout. Subjects received a single SC dose of TILA-278 delivered by either the PFS or the AI, using the same formulation, concentration, and nominal fill volume; both devices delivered into the abdomen. The primary comparison was of Cmax~ and AUC between devices.

Exposure was comparable between the two presentations. The geometric-mean ratios (AI/PFS) for Cmax and AUC, with their 90% confidence intervals, fell entirely within the conventional 0.80–1.25 comparability interval (Table 2.7.1-5), supporting equivalent systemic delivery from the PFS and the AI.

Table 2.7.1-5. Device-Bridging PK Comparison, Autoinjector vs Prefilled Syringe (Study TILA278-102)

Parameter	PFS geometric mean	AI geometric mean	GMR (AI/PFS)	90% CI
Cmax (µg/mL)	20.8	21.4	1.03	0.92 – 1.15
AUC0–∞ (µg·day/mL)	396	405	1.02	0.94 – 1.11
Tmax (days), median	6.0	6.0	—	—

Local tolerability was consistent between devices, with injection-site reactions being the most frequent local finding and no meaningful device-related difference in their incidence or severity. No new safety signals were attributable to the autoinjector.

2.7.1.3 Comparison and Analyses of Results Across Studies

2.7.1.3.1 Bioanalytical Method Consistency

A single validated, ADA-aware, drug-tolerant PK method (Section 2.7.1.2.1.1) and a single tiered immunogenicity strategy (Section 2.7.1.2.1.2) were applied across the clinical program, including the pivotal Phase 2b study TILA278-201. In-study assay performance (calibration-curve acceptance, quality-control passing rates, and incurred-sample reanalysis) met ICH M10 acceptance criteria in each contributing study, supporting the comparability and pooling of PK and immunogenicity data across studies. The bispecific "both-arms-engaged" capture/detection format ensured that the reported concentrations reflect functionally intact drug throughout, and the demonstrated drug tolerance of the ADA assay ensured reliable immunogenicity ascertainment at clinically relevant trough concentrations.

2.7.1.3.2 Bioavailability, Absorption, and Dose Proportionality

Across the SC dose range studied, TILA-278 displayed slow lymphatic-mediated absorption (median Tmax ≈ 6 days), an absolute SC bioavailability of approximately 64%, and a terminal half-life of approximately 18 days under conditions of saturated target-mediated clearance. Systemic exposure increased more than dose-proportionally with increasing dose, consistent with TMDD. These properties are internally consistent between the single- and multiple-dose portions of TILA278-101 and with the exposures observed at the High and Low SC dose levels evaluated in the pivotal induction study TILA278-201, in which a clear dose-ordered efficacy response was observed (clinical remission at Week 12: High 37.3%, Low 16.2%, Placebo 0.7%). The exposure–response relationship supporting dose selection is presented in Module 2.7.2.

2.7.1.3.3 Formulation and Device Interchangeability

The PFS and AI presentations share identical formulation, concentration, primary container/closure, and fill volume, and delivered equivalent systemic exposure in the dedicated bridging study (all Cmax and AUC 90% confidence intervals within 0.80–1.25; Table 2.7.1-5), with comparable local tolerability. Together with the quality comparability data in Module 3.2.P, these results support the interchangeable use of the PFS and AI for the commercial product. No formulation change requiring an additional in vivo bioequivalence bridge was introduced after establishment of the clinical formulation used in TILA278-201.

2.7.1.3.4 Overall Conclusions

The biopharmaceutics program for TILA-278 is appropriate and complete for an SC-administered bispecific IgG1 monoclonal antibody indicated for moderate-to-severe UC:

• Oral bioavailability, food-effect, in vitro dissolution, and dissolution-based IVIVC assessments are scientifically not applicable to this parenteral protein therapeutic and were justifiably not conducted.
• A validated, drug-tolerant, ADA-aware PK assay measuring functionally intact bispecific drug, together with a tiered immunogenicity assay strategy of adequate sensitivity and drug tolerance, provides a robust analytical foundation for all PK, exposure–response, and immunogenicity conclusions in the dossier.
• TILA-278 is absorbed slowly following SC injection with an absolute bioavailability of approximately 64% and a long terminal half-life, exhibiting the greater-than-dose-proportional, target-mediated disposition expected for this modality.
• The prefilled syringe and autoinjector presentations are bioequivalent and interchangeable.

No unresolved biopharmaceutic issues have been identified. Supporting detail is provided in Module 2.7.2 (Clinical Pharmacology), Module 3.2.P (Drug Product), and the individual study and validation reports in Module 5.3.