Thawer, Alia

Abstract Background Grade 3 gastroenteropancreatic neuroendocrine neoplasms (G3 GEPNENs) are often aggressive, and the optimal treatment is unclear for this subgroup of neuroendocrine neoplasms (NENs). Temozolomide (TEM)-based regimens have been increasingly used to treat grade 1–2 NENs, but their efficacy in G3 NENs remains undetermined. We aimed to assess the clinical efficacy of TEM-containing regimens in advanced grade 3 GEPNENs. Materials and Methods A multicenter retrospective review (2008–2018) of patients with metastatic/unresectable G3 GEPNENs who received a TEM-containing regimen was undertaken within a North American partnership to pool data. The primary endpoint was time to treatment failure (TTF). Radiologic response was extracted from local reports. Results One hundred and thirty patients in six high-volume NEN centers were included (median age 55, 64% male, 18% functional, 67% pancreatic NEN). Forty-nine percent were well-differentiated, 35% poorly differentiated, and 15% unknown based on local pathology reports. The regimen used was capecitabine and temozolomide (CAPTEM) in 92% and TEM alone in 8%. Radiological response by local assessment was seen in 36% of patients. Median TTF was 3.6 months and median overall survival (OS) 19.2 months. Six percent of patients required discontinuation of therapy due to adverse events. TTF was longer in first-line treatment (7.8 months vs. 2.9 months; hazard ratio, 1.62; 95% confidence interval, 1.11–2.36; p = .015) and in patients with pancreatic NENs (panNENs) compared with gastrointestinal NENs (5.8 months vs 1.8 months; p = .04). The overall response rate was higher in the first-line setting (51% vs 29%; p = .02) and in panNEN (41% vs 23%; p = .04). Conclusion This is the largest TEM treatment series in G3 NEN, involving collaboration of several major North American NEN centers as a partnership. Thirty-six percent of patients showed some degree of radiographic response, and treatment was generally well tolerated, although the median duration of response was short. Response rates and time to treatment failure were superior in the first-line setting. CAPTEM should be considered a viable treatment option in this setting. Further randomized trials are warranted. Implications for Practice Neuroendocrine neoplasms (NENs) are heterogeneous, and optimal treatment for aggressive grade 3 (G3) NENs remains undetermined. The capecitabine and temozolomide (CAPTEM) regimen has been used in low-grade pancreas NENs but there are few data for its safety and efficacy in the G3 setting. This article reports on the efficacy of temozolomide-containing regimens, particularly CAPTEM, in management of G3 NENs. The good tolerance and response rate show that CAPTEM should be considered a viable regimen in treatment of G3 NENs pending confirmatory prospective studies.

321 Background: G3 NENs are aggressive, and optimal systemic treatment is unclear. Temozolomide (TEM)-based regimens have been used to treat grade 1-2 NETs, but their efficacy in G3 NENs (Ki-67 > 20%) remains undetermined. Aims: To assess the clinical efficacy of TEM-containing regimens in advanced grade III gastroenteropancreatic NENs (GEPNENs). Methods: A multicentre retrospective review (2008-2017) of patients with metastatic/unresectable G3 GEPNENs who received a TEM-containing regimen. The primary endpoint was time to treatment failure (TTF). Radiologic response was extracted from local reports without formal RECIST criteria. Results: 118 patients in six centers were included (median age 55, 65% male, 15% functional, 75% pancreatic NEN). 57% were well-differentiated, 35% poorly-differentiated, and 18% unknown based on local pathology reports. The regimen used was CAPTEM in 93% and TEM in 7%. Best radiological responses were: complete response (1%), partial response (39%), stable disease (22%), progressive disease (31%), unknown (7%) not by RECIST. Median TTF was 150 days and median overall survival (OS) 18.0 months. Fifteen patients (14%) required dose reductions/discontinuation due to adverse events. TTF was shorter for patients on TEM alone (p = 0.02, Table 1). Well-differentiated NENs had better response rate (52% vs 26%, p = 0.02) and overall survival (30.1 vs 12.0 mo, p = 0.008) compared to poorly-differentiated NEN. Conclusions: This is the largest TEM treatment series in G3 NEN, involving collaboration of several major North American NET centers. 40% of patients showed some degree of response, and treatment was generally well-tolerated. TEM-based regimens should be considered a viable treatment option in this setting. Prospective confirmatory trials (such as EA2142) may face difficulties in accrual due to disease rarity. [Table: see text]