Purpose: The CANON (CAVATAK in NON-muscle invasive bladder cancer) study evaluated a novel ICAM-1-targeted immunotherapeutic-coxsackievirus A21 as a novel oncolytic agent against bladder cancer.

Experimental Design: Fifteen patients enrolled on this 'window of opportunity' phase 1 study, exposing primary bladder cancers to CAVATAK prior to surgery. The first nine patients received intravesical administration of monotherapy CAVATAK; in the second stage, six patients received CAVATAK with a sub-therapeutic dose of mitomycinC, known to enhance expression of ICAM-1 on bladder cancer cells. The primary endpoint was to determine patient safety and maximum tolerated dose. Secondary endpoints were evidence of viral replication, induction of inflammatory cytokines, anti-tumour activity and viral-induced changes in resected tissue.

Results: Clinical activity of CAVATAK was demonstrated by induction of tumour inflammation and haemorrhage following either single or multiple administrations of CAVATAK in multiple patients, and a complete resolution of tumour in one patient. Whether used alone or in combination with mitomycinC, CAVATAK caused marked inflammatory changes within NMIBC tissue biopsies by up-regulating interferon-inducible genes including both immune checkpoint-inhibitory genes (PD-L1 and LAG3) and Th1-associated chemokines as well as induction of the innate activator RIG-I, compared to bladder cancer tissue from untreated patients. No significant toxicities were reported in any patient, from either virus or combination therapy.

Conclusions: The acceptable safety profile of CAVATAK, proof of viral targeting, replication and tumour cell death together with the virus-mediated increases in "immunological heat" within the tumour microenvironment all indicate that CAVATAK may be potentially considered as a novel therapeutic for NMIBC.