In its first readout since it changed its name from Eleven Biotherapeutics, Sesen Bio presented three-month data for its bladder cancer treatment Vicinium at the annual meeting of the American Urological Association.
The Vista trial enrolled 133 patients with high-grade, non-muscle-invasive bladder cancer (NMIBC) who had previously been treated with the standard-of-care bacillus Calmette-Guérin (BCG) immunotherapy. The efficacy data, from 111 patients with cancer that had not spread from the bladder into muscle or other tissue, show that Vicinium had a complete response rate of 43%.
NMIBC primarily affects men and is typically treated with surgery. But this isn't always effective; about 60% of patients diagnosed with NMIBC will also undergo BCG immunotherapy. And even BCG isn't a sure thing.
Vicinium, a next-generation antibody-drug conjugate, is being developed as an alternative to losing the bladder. It comprises a recombinant fusion protein that targets epithelial cell adhesion molecule (EpCAM) antigens to deliver Pseudomonas exotoxin A. EpCAM is overexpressed in NMIBC but not in healthy bladder cells, the company says, so Sesen thinks zeroing in on it will decrease toxic effects in healthy tissues.
It was well-tolerated, Sesen said, with 72% of the adverse events classed as grade 1 or 2. But, four treatment-related serious adverse events were reported, including acute kidney injury or renal failure and cholestatic hepatitis, the company said, as its stock was down 5% this morning, likely on those safety results.
“The positive, three-month data from the VISTA Trial support Vicinium’s potential to offer a new and completely different treatment option for patients who need it,” said Donald Lamm, M.D., of BCG Oncology in Phoenix in the release. “In contrast to the many other advances in cancer therapy, treatment for high-grade NMIBC has suffered from little innovation, and Vicinium represents a unique approach with a targeted protein, an entirely new mechanism for treating this disease."
Sesen expects 12-month data to read out in mid-2019.
Eleven Bio merged with Viventia Bio in 2016, a move that came after its late-stage drug EBI-005 (isunakinra) failed a phase 3 trial in dry eye disease and the struggling company slashed about 70% of its staff. While the combined company kept Eleven's name, Viventia's leadership essentially took control of the company and set about executing its cancer-focused strategy. Eleven rebranded as Sesen earlier this month.