AUA 2021: Antibody Levels as Predictors of Response to Immunotherapy in Bladder Cancer
Posted: Friday, October 1, 2021
Anirban P. Mitra, MD, PhD, of The University of Texas MD Anderson Cancer Center, Houston, and colleagues conducted a secondary analysis of a phase III trial that assessed the predictive value of antiadenoviral antibody levels on therapeutic response in patients with non–muscle-invasive bladder cancer receiving nadofaragene firadenovec—a recombinant, adenoviral vector–based intravesical therapy. During the 2021 American Urological Association (AUA) Annual Meeting (Abstract PD09-02), these researchers revealed that a combination of antibody fold-change levels and titers may, in fact, predict therapeutic response.
This study focused on 157 patients with high-grade, bacillus Calmette-Guérin (BCG)-unresponsive non–muscle-invasive bladder cancer who were administered nadofaragene firadenovec therapy. Participants received 75 mL of treatment intravesically once every 3 months for up to four doses. Serum antibody levels were obtained 1 to 24 hours before treatment and every 3 months until 1 year or study withdrawal.
The rate of complete response was 60% at the 3-month follow-up, and this rate was maintained in 51% of patients during the 12-month follow-up. A total of 91 participants had evaluable antibody levels, and 57 individuals had carcinoma in situ. At the 12-month mark, 52% of patients were high-grade recurrence-free.
Antibody titers while on therapy were either at or above baseline levels, with 89% of responders and 59% of nonresponders exhibiting titers higher than 800 U/mL (P = .001). Additionally, there was an on-treatment antibody fold-change of more than eight from baseline in 51% of responders and 27% of nonresponders (P = .02). Furthermore, a combination of elevated antibody titers and fold-change levels were observed in 47% and 18% of responders and nonresponders, respectively (P = .004).
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