Atezolizumab Shows Potential In First-Line Metastatic Urothelial Cancer Setting

Cisplatin-ineligible patients with metastatic urothelial carcinoma may respond to atezolizumab administered as first-line therapy

medwireNews: Research presented at the American Society of Clinical Oncology annual conference shows that atezolizumab has clinically meaningful activity and is well tolerated when administered as initial therapy for patients with metastatic urothelial carcinoma who are unsuitable for cisplatin.

Arjun Balar, from NYU Langone Medical Center in the USA, who presented the IMvigor210 findings on behalf of his colleagues, told the audience in Chicago, Illinois, USA, that “these data do make a compelling argument for atezolizumab to become a potential new standard of care in the first-line setting and further studies are certainly planned in this population.”

The anti-programmed death ligand 1 (PD-L1) antibody was given to 119 patients who had not previously received chemotherapy for metastatic disease and met the criteria for cisplatin ineligibility (estimated glomerular filtration rate between 30 and 60 mL/min per 1.73 m2, grade 2 or worse hearing loss or peripheral neuropathy, or a EGOG performance status of 2).

After a median follow-up of 14.4 months, treatment with intravenous atezolizumab 1200 mg administered once every 3 weeks resulted in an objective response rate (ORR) of 24%, with 7% of patients having a complete response and 17% a partial response. At data analysis, 75% of responses were ongoing.

Responses were observed in all subgroups based on PD-L1 expression on tumour infiltrating immune cells (ICs). Specifically, the ORRs by subgroup were 21% for the 39 IC0 patients (<1% PD-L1–positive cells), 23% for the 48 IC1 patients (≥1% but <5%) and 28% for the 32 IC2/3 patients (≥5%), with complete responses achieved in all subgroups.

Median overall survival for the entire cohort was estimated at 14.8 months, which is “very promising”, especially given that with only 47% of participants experiencing an event thus far, the cohort remains immature, said the presenting author.

Treatment-related adverse events of grade 3 or 4 occurred in 12% of study participants, and one patient had treatment-related grade 5 sepsis. Moreover, 3% of participants experienced an immune-mediated side effect of grade 3 or 4.

Thirty-five percent of patients required a dose interruption due to a side effect. But only 6% discontinued the study drug.

Arjun Balar concluded: “The durable nature of response and favorable [adverse event] profile makes this an attractive alternative to chemotherapy.”

Reference

Balar AV, Galsky MD, Loriot Y, et al. Atezolizumab as first-line therapy in cisplatin-ineligible locally advanced/metastatic urothelial carcinoma: Primary analysis of IMvigor210 cohort 1. J Clin Oncol 2016; 34 (suppl; abstr LBA4500).

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