Chemoradiation With Enadenotucirev as a Radiosensitiser in Locally Advanced Rectal Cancer

Description

At present identifying novel radiosensitising agents in colorectal cancer is an area of high need for patients considering sphincter preserving surgery or needing down staging to facilitate surgery.

Although the combination of Enadenotucirev with chemoradiation is novel, there is a wealth of evidence to support the rationale for combining this class of agent with radiation and chemotherapy.

Enadenotucirev is a group B oncolytic virus under development for the systemic treatment of metastatic or advanced epithelial tumours. Enadenotucirev is a chimeric adenovirus type 11p (Adp/adenovirus type 3 (Ad3) virus, discovered through a process of bio-selection from a library of chimeric viruses produced from a pool of adenoviruses from seven different serotypes utilizing human HT-29 colorectal cancer (CRC) cells.

Enadenotucirev shows selective and potent toxicity in humans carcinoma cells with only very limited or no toxicity to normal (non-cancerous) human cells. Other than humans, there is no known permissive species for Enadenotucirev. The principle advantage of oncolytic therapy is that the virus replicates only in diseased cells meaning that the concentration of drug is amplified at the site of pathology so that it is higher in the tumour than in healthy tissue. Virus particles spread from cell to cell within a tumour nodule until they reach non-permissive normal tissues, in principle destroying all viable tumour cells they encounter.

While the overall understanding of the mechanism of action of Enadenotucirev in humans is still under investigation, it is now well established from non-clinical and clinical studies that the mechanism of anti-cancer efficacy of oncolytic viruses not only involves direct infection and lysis of tumour cells, but that immune responses stimulated via an increased release of tumour-associated antigens and immune-inflammatory activation signals play a key role.

CEDAR is dual endpoint, dose escalation phase 1 trial using a time to event continual reassessment method (TiTECRM). Response and Toxicity endpoints will be combined in dose escalation models to identify the optimal dose schedule. Dose decisions are made using the statistical model instead of just using the data from that particular dose, as in the case of 3+3 model, meaning it uses all available data to make a dose decision.

This primary objective is to determine the optimal dose and frequency of the virus by firstly gradually increasing the number of doses each successive patient receives, and then increasing the dose of the virus itself. All participants will receive 3 loading doses in weeks 1-2, prior to initiation of standard chemoradiotherapy. Further doses of Enadenotucirev will either be given after or during and after standard chemoradiotherapy and this is dependent on which of the 6 different dose groups they are assigned to. The dose given will vary between either 1x1012 Viral Particles (VP) or 3x1012vp.

Each patient will receive a minimum of 3 doses, up to a maximum of 8, spread over the course of 9 weeks. Patients will be closely monitored at all times to ensure that with each dosing group, there aren't excessive side effects.

Patients will then undergo surgery as part of their standard of care and be followed up for up to 24 months to determine the long term effects of this treatment.

Data on progression free survival and loco-regional failure will be requested from the routine clinical care team at 12 and 24 months.

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