Atezolizumab plus bevacizumab safe, effective in malignant peritoneal mesothelioma
Atezolizumab plus bevacizumab appeared well-tolerated and resulted in a 40% objective response rate among patients with malignant peritoneal mesothelioma, according to phase 2 study results published in Cancer Discovery.
“Peritoneal mesothelioma is truly an orphan disease, with most of the attention in mesothelioma focused on pleural mesothelioma. There is little dedicated research toward this disease — we can probably count on one hand the number of trials that have been conducted for peritoneal mesothelioma,” Kanwal Raghav, MD, associate professor of gastrointestinal medical oncology at The University of Texas MD Anderson Cancer Center, told Healio. “We conducted this study because of the lack of treatment options for these patients, and we attempted to explore a good treatment option in terms of a combination of the two drugs, which we feel is much better than either of the drugs alone.”
Only about 300 to 500 Americans are diagnosed with malignant peritoneal mesothelioma annually, researchers estimated.
Raghav and colleagues assessed the safety and efficacy of atezolizumab (Tecentriq, Genentech), which targets PD-L1, combined with bevacizumab (Avastin, Genentech), a VEGF inhibitor, in a cohort of 20 patients (median age, 63 years; 60% women; 80% white) with advanced and unresectable peritoneal mesothelioma who exhibited disease progression on (85%) or intolerance to (15%) prior platinum-pemetrexed chemotherapy.
Results showed a confirmed objective response rate per RECIST version 1.1 by independent radiology review of 40% (95% CI, 19.1-64), with a median response duration of 12.8 months. Six responses persisted for more than 10 months.
Researchers observed objective responses regardless of PD-L1 expression status and tumor mutational burden.
They reported a 1-year PFS rate of 61% (95% CI, 35-80) and a 1-year OS rate of 85% (95% CI, 60-95).
“In this treatment-refractory population who had already received at least one line of standard treatment, the response rate, OS and PFS achieved on this study were far superior to what would be expected for conventional therapies that we use for these patients in this setting,” Raghav said. “This is an important treatment option for these patients.”
The combination also appeared safe. Half of the patients experienced grade 3 treatment-emergent adverse events, the most common of which included hypertension (40%) and anemia (10%).
Raghav and colleagues plan to explore the combination earlier in the disease course, such as before first-line chemotherapy or in the preoperative setting, where patients who respond well can go on to curative cytoreductive surgery.
“There is a great need to study this orphan disease in a dedicated fashion, and I urge oncologists to provide early referral for these patients to centers where we can continue these studies and continue to generate new data,” he said. “If a clinical trial is not an option or not available, atezolizumab plus bevacizumab should be considered as a potential option for these patients after first-line chemotherapy.”
For more information:
Kanwal Raghav, MD, can be reached at The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030; email: firstname.lastname@example.org.