A First-In-Human Trial of pTTL in Advanced Colorectal Cancer

STUDY RATIONALE The present trial is an open-label, non-randomised FIH trial investigating the safety and tolerability of pTTL, an immunotherapy consisting of autologous T cells activated and expanded in vitro using tumour-specific personalised neoantigens. The scientific rationale for pTTL relies on the fact that somatic mutations in tumour cells arising during malignant transformation result in altered proteins or peptides, so called neoantigens. Each individual tumour harbours multiple mutations that form a unique mutation profile, which enables personalisation of each therapeutic product. The neoantigens distinguish tumour cells from normal cells and make the tumour cells targetable by the immune system, and also allows targeting of several targets in the tumour simultaneously. In the present trial, up to 36 neoantigens will be targeted.

The starting material for pTTL is derived from tumour-draining regional lymph nodes (RLNs). The choice of this source of T cells is based on several advantages: The exposure to tumour antigens and, in the case of metastasis, tumour cells causes an enrichment of tumour- specific T cells. These T cells also have the potential to be superior to tumour-infiltrating T cells due to less exposure to tumour-mediated immunosuppression.

The production process for pTTL includes in vitro expansion, which increases the neoantigen-reactive T cell population. The selective T cell expansion is achieved by stimulation with protein constructs containing neoantigen epitopes, based on sequencing data from each patient's own tumour. This improves the chance of effective cancer cell eradication by both increasing the number of cells able to recognise and respond to the tumour, and by breaking immunological tolerance created in vivo by immunosuppressive mechanisms through activation in a non-suppressive environment.

PATIENTS The selected target group of the trial is adults with stage IV CRC. Patients may be considered eligible for inclusion if they have received treatments according to standard of care or if further standard of care treatment options are judged not to be in the patients' best interest (e.g. due to toxicity issues). Patients could also be eligible for inclusion in the trial during a scheduled pause in ongoing palliative therapy, at the discretion of the treating Investigator. Eligible patients must have a primary or metastatic lesion that is accessible to biopsy or surgery to obtain tumour material for NGS analysis. In addition, it is a requirement that the patient can undergo surgical excision of RLNs for use in pTTL production. Eligible patients should also have a good performance status (ECOG 0-1) and organ function, and no pre-existing conditionings deemed to increase their risk for severe side effects of pTTL therapy. Materials for Part I of the trial can be collected, while non-curative therapeutic options remain, and cryopreserved for later use if the patient should become eligible for inclusion in Part II.

METHODOLOGY The trial is composed of 3 parts, referred to as Part I, Part II and Part III.

Patients will be consented separately for Part I and for Part II/III: a first consent is given for tissue collection and pTTL production, and a second consent is given for pTTL treatment, including pre-conditioning chemotherapy and follow-up.

Part I of the trial entails patient identification, recruitment and screening of trial patients. It also comprises production of pTTL, which is performed in 3 steps:

1. Collection of tumour samples and normal samples for NGS and neoantigen selection. Production of stimulatory NAG-coupled beads raw material TC0301.
2. Collection of starting material for pTTL manufacturing from RLN.
3. pTTL manufacturing.

The time required from collection of tumour material and RLNs up until pTTL production and administration to the patient is approximately 8 to 12 weeks. The RLN starting material is cryopreserved after initial processing, enabling flexibility in the timing of pTTL administration.

Part II of the trial entails pre-conditioning and supportive care therapy, treatment with pTTL, and 26 weeks safety follow-up.

Pre-conditioning contains cyclophosphamide and fludarabine, and will be administered between Day -7 and Day -5 before scheduled pTTL administration. Supportive care treatment will start on Day -9 or Day -8. pTTL administration will normally be administered on Day 1, with the option of administration on Day -3 if cell expansion kinetics during pTTL production indicates this would be preferable. Part II will end when the last treated patient has been followed for 26 weeks or earlier in case of death or patient withdrawal.

Part III of the trial is a long-term follow-up initiated after completion of the initial 26 weeks safety follow-up period. Patients will participate in Part III for up to 4.5 years after end of Part II or until death, whichever comes first.

pTTL DOSAGE AND ADMINISTRATION The drug product (DP), i.e. pTTL, is composed of in vitro expanded RLN cells, enriched for neoantigen-specific T cells. It is formulated as a cell suspension with the excipients NaCl (9 mg/mL) and human serum albumin (25 mg/mL) in a transfusion bag intended for intravenous transfusion. The product is administered fresh. Each patient will receive a single administration of pTTL.The cell dose obtained during the manufacturing process will vary depending on the size of the neoantigen-reactive clones present in the starting material and their proliferative capacity. The minimum dose of a pTTL unit is 20 million viable cells and the maximum dose is 1 billion viable cells.