IMvigor010: No atezolizumab benefit for muscle-invasive urothelial carcinoma
medwireNews: For patients with high-risk muscle invasive urothelial carcinoma (MIUC), adjuvant atezolizumab does not significantly extend disease-free survival compared with observation alone, the IMvigor010 investigators say.
The phase 3 trial results were presented at the virtual 2020 ASCO Annual Meeting by Maha Hussain, from the Robert H Lurie Comprehensive Cancer Center, Northwestern University in Chicago, Illinois, USA.
The study participants had undergone radical cystectomy or nephroureterectomy with lymph node dissection within the previous 14 weeks for high-risk MIUC affecting the bladder, renal pelvis, or ureter, and many had also received neoadjuvant chemotherapy.
The primary endpoint of intention-to-treat disease-free survival (DFS) was a median 19.4 months for the 406 patients who were randomly assigned to receive adjuvant atezolizumab 1200 mg every 3 weeks for 16 cycles or 1 year.
This was comparable to the median 16.6 months achieved by the 403 patients who instead received only observation every 3 weeks, giving a hazard ratio (HR) for disease progression or death of 0.89 that did not reach significance.
DFS also did not differ significantly between the atezolizumab and control arms when patients were subgrouped by PD-L1 status, although Hussian did note that “there appears to be a prognostic effect for IC2/3 PD-L1 status by comparison to the IC0 and 1, as reflected by a better appearing disease-free survival”. She cited HRs of 1.01 and 0.81, respectively.
Nor was there any DFS gain with atezolizumab among any of the other patient clinical subgroups, including disease site or stage, pathologic node status, prior use of neoadjuvant chemotherapy, or geographical location in Asia, Europe, or North America.Median overall survival (OS) was not reached in either the atezolizumab or the observation arm in the interim analysis; the 18-month rates were 79 and 73 months, respectively.
“OS follow-up is ongoing,” Hussain told delegates. “Additional exploratory biomarker and subgroup analyses may warrant further study.”
The presenter noted that the atezolizumab safety profile was “consistent” with earlier reports in patients with advanced disease. Treatment-related grade 3–4 adverse events occurred in 16% of patients, and there was one treatment-related death. Immune-mediated grade 3–4 events occurred in 9% of patients, most commonly rash, colitis, and hepatitis, affecting 2% each.
She concluded that “other clinical trials with atezolizumab as monotherapy and combination therapy are underway in the metastatic, non-muscle invasive, and bladder preservation UC settings”.
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