Combination Bevacizumab Plus Atezolizumab May Effectively Treat Some Neuroendocrine Tumors

By Marilynn Larkin

April 13, 2022

NEW YORK (Reuters Health) - In patients with neuroendocrine tumors (NETs), combination therapy with bevacizumab and atezolizumab may improve some outcomes, a nonrandomized trial suggests.

"While one small single-arm study cannot and should not change practice, the supportive translational data suggest that we may have the capability of activating the immune system in a subset of patients with NETs, which is quite encouraging," Dr. Daniel Halperin of the University of Texas MD Anderson Cancer Center in Houston told Reuters Health by email.

"Fortunately," he added, "there are additional ongoing studies exploring similar approaches, such as NCT03290079 (https://bit.ly/3rik6cs), and we are hopeful that our colleagues will be able to build on the observations we present in this manuscript, so we can continue to move our field toward effective immunotherapy options for our patients."

Therapies for patients with advanced well-differentiated NETs "have expanded but remain inadequate, with patients dying of disease despite recent advances," Dr. Halperin and colleagues write in JAMA Oncology. "While patients with other cancers have seen long-term disease control and tumor regression with the application of immunotherapies, initial prospective studies of single-agent programmed cell death 1 inhibitors in NET have been disappointing."

To assess the response rate following treatment with the vascular endothelial growth factor inhibitor bevacizumab plus the programmed cell death 1 ligand 1 inhibitor atezolizumab, Dr. Halperin and colleagues conducted a single-arm, open-label nonrandomized trial with 40 patients (median age, 59; 35%, female) with advanced, progressive grade 1 to 2 NETs, including 20 with pancreatic NETs (pNETs) and 20 with extrapancreatic NETs (epNETs).

Patients received intravenous bevacizumab and atezolizumab at standard doses every three weeks until progression, death, or withdrawal from the study. The primary end point was objective radiographic response; the secondary end point was progression-free survival (PFS).

Four patients with pNETs (20%) had an objective response, as did three (15%) with epNETs. The PFS was 14.9 months and 14.2 months, respectively.

Commenting on the study, Dr. Namrata (Neena) Vijayvergia, Assistant Chief, Gastrointestinal Medical Oncology at Fox Chase Cancer Center in Philadelphia, called the results "encouraging." However, she noted, "We know that bevacizumab alone, given with somatostatin analogs, has a response rate of 12% and median PFS of around 16 months in carcinoid tumors - comparable to the epNET arm of this study - as shown by the S0518 trial (https://bit.ly/3E7yKZ8). So the added benefit of atezolizumab is little, if any."

"We need prospective comparative trials to address the role of immuno-oncology combinations in NETs," Dr. Vijayvergia concluded.

SOURCE: https://bit.ly/3E8MClV JAMA Oncology, online April 7, 2022.

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