Novel FDA-Approved Agents

Pembrolizumab is a humanised monoclonal antibody targeting the programmed death-1 (PD-1) receptor on T lymphocytes. By blocking the PD-1/PD-L1 interaction, pembrolizumab restores T-cell mediated anti-tumour immunity that is often suppressed in the tumour microenvironment. It was the first systemic immunotherapy approved for NMIBC.

The KEYNOTE-057 trial (Cohort A) enrolled 148 patients with BCG-unresponsive CIS with or without papillary disease. Patients received pembrolizumab 200 mg IV every 3 weeks for up to 24 months. The complete response (CR) rate was 41% at 3 months, with a median duration of response of 16.2 months. Approximately 46% of responders maintained CR at 12 months.

Treatment-related adverse events of grade 3–4 severity occurred in 13% of patients, consistent with the known safety profile of pembrolizumab in other indications. Immune-related adverse events included hypothyroidism (8%), colitis (2%), and pneumonitis (1%). No treatment-related deaths were reported.

Nadofaragene firadenovec is a first-in-class, non-replicating adenoviral vector-based gene therapy that delivers the human interferon alfa-2b (IFN-α2b) gene directly to urothelial cells. Upon intravesical instillation, the adenoviral vector transduces bladder epithelial cells, which then produce and secrete IFN-α2b locally, creating sustained high concentrations of this anti-tumour cytokine within the bladder microenvironment.

The pivotal Phase III trial enrolled 157 patients with BCG-unresponsive high-risk NMIBC (103 with CIS ± Ta/T1, 54 with high-grade Ta/T1 without CIS). Nadofaragene was administered intravesically every 3 months. In the CIS cohort, the complete response rate was 53.4% at 3 months, with 24.3% maintaining CR at 12 months. In the papillary-only cohort, the high-grade recurrence-free rate was 72.9% at 12 months.

The safety profile was favourable, with the most common adverse events being bladder-related (dysuria 11%, urgency 7%, haematuria 6%). No grade 4 or 5 treatment-related adverse events were reported. The intravesical route of administration avoids systemic immune-related toxicities seen with checkpoint inhibitors.

Nogapendekin alfa inbakicept is a first-in-class IL-15 receptor agonist that combines a novel IL-15 superagonist with the IL-15 receptor alpha-Fc fusion protein. This complex activates and expands NK cells and CD8+ T cells — key effectors of anti-tumour immunity — while avoiding the activation-induced cell death that limits native IL-15 signalling. Critically, it is administered in combination with BCG, potentially synergising with BCG's immunostimulatory effects.

The QUILT-3.032 trial enrolled 77 patients with BCG-unresponsive NMIBC with CIS. Patients received intravesical nogapendekin alfa combined with BCG. The complete response rate was 62% at any time point, with 52% maintaining CR at 12 months — the highest durable response rate reported among approved agents for this indication.

The combination was generally well tolerated, with the most common adverse events being local bladder symptoms (dysuria, frequency, urgency) and flu-like symptoms consistent with immune activation. Grade 3 adverse events occurred in approximately 20% of patients, with no grade 4–5 treatment-related events.