Combination treatment with N-803, an investigational immunotherapy, and bacillus Calmette-Guérin (BCG) is safe and efficacious for treating carcinoma in situ (CIS) and papillary non-muscle invasive bladder cancer (NMIBC) unresponsive to BCG alone, new research suggests.
“This combination of BCG and N-803 results in significant complete response rates and long-term disease-free rates without significant systemic side effects,” study investigator Sam S. Chang, MD, of Vanderbilt University Medical Center in Nashville, Tennessee, said in an interview.
“Although direct comparisons [with BCG alone] have not been performed, these results are very promising,” he added.
Dr Chang presented these results, from a phase 2/3 trial (ClinicalTrials.gov Identifier: NCT03022825) at the ASCO Genitourinary Cancers Symposium 2022.
Dr Chang explained that N-803 is a high affinity, interleukin 15 immunostimulatory fusion protein that promotes the proliferation and activation of natural killer cells and CD8+ T cells without binding to regulatory T cells.
The researchers theorized that combining N-803 with BCG would boost innate immune memory and prolong the duration of response to therapy.
Dr Chang and colleagues tested that theory in 83 patients with CIS and 77 with papillary NMIBC. Dr Chang noted that both patient groups were heavily pretreated, with a median of 12 prior BCG doses in each group.
All patients received intravesical N-803 plus BCG. The median follow-up was 23.9 months for the CIS group and 20.7 months for the papillary group.
In the CIS group, the complete response rate was 71%. At 12 and 24 months, 62% and 52% of patients, respectively, had maintained a complete response.
The median duration of response in the CIS group was 24.1 months, and 93% of responders avoided cystectomy. At 24 months, the bladder cancer-specific progression-free survival rate was 91%, and the bladder cancer-specific overall survival rate was 100%.
The papillary NMIBC group had 12- and 24-month disease-free survival (DFS) rates of 57% and 48%, respectively. The median DFS was 23.6 months, and 95% of patients did not require cystectomy. At 24 months, the bladder cancer-specific overall survival rate was 99%.
In both groups, there were no grade 4 or 5 treatment-related adverse events (TRAEs). The incidence of any grade 3 TRAEs was below 1%. There were no serious TRAEs and no immune-related events.
The most common grade 1-2 TRAEs were dysuria (22%), pollakiuria (19%), and hematuria (18%).
Given the observed efficacy and safety profile, N-803 represents a “significant advance” in the treatment of BCG-unresponsive CIS and papillary NMIBC, according to the investigators.
Disclosures: This research was supported by ImmunityBio, Inc. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.
Chang SS, Chamie K, Gonzalgo ML, et al. Positive efficacy and safety phase 3 results in both CIS and papillary cohorts BCG-unresponsive nonmuscle invasive bladder cancer (NMIBC) after IL-15RαFc superagonist N-03 (Anktiva) and BCG infusion. Presented at ASCO GU 2022; February 17-19, 2022. Abstract 431.
This article originally appeared on Cancer Therapy Advisor