A Phase 1-2 Master Protocol to Study Intravenous ATTR-01 in Adult Participants with Select Epithelial Solid Tumours Under Multiple Sub-protocols (ATTEST)

Overview

Sponsor-declared trial summary

Key facts

Sponsor

Accession Therapeutics Limited

Participant type

Patients

Age range

18-64 years, 65+ years

Gender

Male and Female

Therapeutic area

Diseases [C] - Neoplasms [C04]

Trial duration

23 Jan 2026 → ongoing

Decision date (initial)

2025-04-30

Transition trial

No

Low-intervention

No

Rare-disease indication

No

Vulnerable population

No

Funding sources

Accession Therapeutics Limited

Trial design

CTIS Part I — objectives, methods, condition coding

Main objective

Scope: Therapy, Pharmacokinetic, Safety, Pharmacodynamic, Dose response, Efficacy

• To evaluate the safety and tolerability of ATTR-01 in participants with select solid epithelial tumours (this is a secondary objective in SP B)
• Where applicable for sub-protocols incorporating dose escalation: To determine the optimal dose of ATTR-01 for further development of ATTR-01 in participants with select epithelial solid tumours
• To evaluate the anti-tumour activity of ATTR-01 in participants with select solid epithelial tumours (does not apply to SP A)

Secondary objectives 3

1. To further evaluate the anti-tumour activity of ATTR-01 in participants with select solid epithelial tumours
2. To evaluate the viral persistence of ATTR-01
3. To evaluate the immunogenicity of ATTR-01

Conditions and MedDRA coding

Select Epithelial Solid Tumours

Regulatory references

Scientific advice from competent authorities

European Medicines Agency

Plan to share IPD

No

Eligibility criteria

Principal inclusion / exclusion criteria as submitted by sponsor

Inclusion criteria 12

1. Consenting male and female adults (≥ 18 years of age) with select solid epithelial tumour indications known to have high frequency (≥75%) of αvβ6 integrin receptor expression as detailed in the applicable SP.
2. Prior immune checkpoint antibody therapies as single agents or in combination with other anti-cancer agents is permissible.
3. Received and failed/intolerant of Standard of Care (SoC) therapy where eligible (not including neoadjuvant).
4. Tumour lesion (not previously irradiated), suitable for safe pre- and post-treatment biopsies.
5. Measurable disease by Response Evaluation Criteria in Solid Tumours (RECIST) Version 1.1 (V1.1).
6. Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) of 0 or 1.
7. Minimum life expectancy anticipated to be greater than three months.
8. Willing to undertake appropriate measures of hygiene and protection, including regular hand washing, not sharing personal items (e.g. sharing of towels and cutlery), and avoiding close physical contact with the following groups for ten days after the last administration: a. Women who are pregnant or lactating b. Children under one year old c. Nursing home residents d. Those who have significant immunodeficiency because of underlying illness (e.g. human immunodeficiency virus [HIV]/acquired immunodeficiency syndrome [AIDS]) and/or medication (e.g. systemic corticosteroids).
9. Adequate organ function.
10. Compliant with requirements for prior treatment washout and contraceptive measures applicable to genetically modified organisms (GMOs) and cancer therapies.
11. Applicable to SP-A only: Histologically proven cancer, stage IV, epithelial cancer of an indication as listed in Table 4 in Sub-protocol A.
12. Applicable to SP-A only: Only participants with tumours accessible for biopsy will be considered eligible to enrol.

Exclusion criteria 10

1. Participants with clinically significant fibrotic disease will be excluded. This includes participants with autoimmune diseases such as systemic lupus, rheumatoid arthritis. Participants with idiopathic and occupation-related pulmonary fibrosis will also be excluded.
2. Known prior history of intolerance to anti-PD-1 and/or anti-PD-L1 immunotherapy due to toxicity.
3. Tumour location/extent considered by the investigator to present a significant risk if tumour flare were to occur (e.g. an initial increase in tumour size that may lead to intestinal, airway or ureter obstruction, or penetrating tumour infiltration of major blood vessels, or other hollow organs potentially at risk of perforation).
4. Participants with radiological lymphangitis carcinomatosa.
5. Open/major surgical procedure within eight weeks or minor (day case) surgery within four weeks, prior to administration of the IMP, or any prior surgery without evidence of adequate wound healing.
6. Pre-existing known acute or chronic viral disease (e.g. HIV/Hepatitis B/Hepatitis C).
7. Participants with known prior primary or acquired immune deficiency. Prior splenectomy cases are eligible provided that participants have received post-splenectomy vaccines (pneumococcal, meningococcal and haemophilus influenzae) in keeping with their hospital practice and are either on prophylactic antibiotics or have completed a two-year course.
8. Diagnosed and active bacterial, fungal or viral infections within four weeks of D1 of the IMP administration.
9. Any pre-existing condition requiring use of systemic immunosuppressants.
10. Any active autoimmune disease or chronic inflammatory conditions (apart from: Type 1 diabetes, hypothyroidism requiring thyroxine replacement, chronic skin conditions that do not require treatment or only topical steroids, coeliac disease on dietary control only and diverticulosis).

Endpoints

Primary and secondary outcome measures (English text)

Primary endpoints 3

1. Incidence of AEs, serious adverse events (SAEs), dose limiting toxicities (DLTs), discontinuation of investigational product(s) due to toxicity and clinically significant alterations in vital signs or other clinical safety assessments
2. Objective Response Rate (ORR) from first scan onwards, per RECIST V1.1
3. Duration of Response (DoR)

Secondary endpoints 9

1. Per RECIST V1.1 from first scan onwards: • Disease Control Rate (DCR)
2. Per RECIST V1.1 from first scan onwards: • Time To Response (TTR)
3. Per RECIST V1.1 from first scan onwards: • Progression Free Survival (PFS)
4. Per RECIST V1.1 from first scan onwards: • Overall Survival (OS)
5. Per RECIST V1.1 from first scan onwards: • Maximum reduction in tumour size
6. SP A only: • ORR from first scan onwards, per RECIST V1.1
7. SP A only: • Duration of Response (DoR)
8. ATTR-01 viral persistence/blood concentrations
9. ATTR-01 immunogenicity/anti-ATTR-01 antibodies

Investigational products

Investigational medicinal products (IMPs), comparators, placebo, auxiliary

Test 1

Sponsors and contacts

Sponsor organisations, regulatory contacts, third parties

Accession Therapeutics Limited

Sponsor organisation

Accession Therapeutics Limited

Address

7600c The Quorum, Alec Issigonis Way, Arc Oxford Alec Issigonis Way Arc Oxford

City

Oxford

Postcode

OX4 2UD

Country

United Kingdom

Scientific contact point

Organisation

Accession Therapeutics Limited

Contact name

Hardev Pandha

Public contact point

Organisation

Accession Therapeutics Limited

Contact name

Pia Donaldson

Third parties 2

Locations

1 EU/EEA country · 4 investigational sites

By country

Investigational sites

Country notifications

Trial-start, recruitment-start, end and early-termination notifications submitted per Member State

Results and documents

Annex IV summary of results, Annex V layperson summary, and all documents registered in CTIS for this trial

Documents 14 files

Public protocol annexes, IB summaries, regulatory submissions and post-authorisation documents registered in CTIS.

Application history

3 submissions — initial application plus substantial / non-substantial modifications