Treatment outcomes of recurrent and metastatic adenoid cystic carcinoma: A retrospective analysis.
Authors: McGrath Julie Elaine , Grover Punita , Xiu Joanne , Nabhan Chadi , Choe Jennifer Hsing , Chernock Rebecca , Ikpeazu Chukwuemeka , Shaikh Hira Ghazal , Sukari Ammar , Tang Alice L , Korn Wolfgang Michael , Wise-Draper Trisha Michel 
Published: June 2021

e18056

Background: Adenoid cystic carcinoma (ACC) is a rare malignancy of glandular tissue with a high rate of local recurrence and metastatic disease. Despite being regarded as an indolent disease, the clinical course of recurrent and metastatic ACC (R/M ACC) is highly variable. Responses to chemotherapy (chemo) are uniformly poor. Several multi-targeted tyrosine-kinase inhibitors (mTKIs), EGFR inhibitors (EGFRi) and other targeted agents have been studied in single-arm early phase trials with response rates ranging from 0-16% and progression free survival ranging from 2.5-17 months. However, there have been no comparative clinical trials and it is not known if one treatment strategy is superior. We undertook this retrospective study to assess the real-world clinical outcomes in patients with adenoid cystic carcinoma using the Caris Life Sciences database. Methods: Real world overall survival (rwOS) for cases of ACC was obtained from insurance claims data and Kaplan-Meier estimates were calculated from the date of collection to the date of last contact. Cases were divided into subgroups based on treatment received – chemo (including platinum agents, taxanes, 5FU, topoisomerase inhibitors, anthracyclines), EGFRi (cetuximab, erlotinib, lapatinib), mTKIs (pazopanib, axitinib, sunitinib, cabozantinib, lenvatinib, sorafenib) and immune checkpoint inhibitors (ICIs) (atezolizumab, ipilimumab, pembrolizumab, nivolumab). Results: 368 patients (pts) were identified with ACC, 16 were locally recurrent and 216 tumors were taken from metastatic sites. 50 pts received chemo, 6 were treated with EGFRi and 15 with mTKIs. Pts who received combination EGFRi and chemo or mTKI and chemo were excluded. The median overall survival (mOS) all patients with metastatic ACC was 2.8 years (yrs). The mOS of pts with R/M ACC was 3 yrs for chemo, 2.9 yrs for EGFRi and 1.5 yrs for mTKIs. There was no significance in mOS between chemo vs mTKIs (HR 0.85, 95% CI 0.3 - 2, p = 0.72) and chemo vs EGFRi (HR = 0.88, 95% CI 0.3 - 2.5, p = 0.78). We further compared the outcomes of those treated with EGFRi (n = 8) with mTKIs (n = 19) in the entire cohort. For most pts, these agents were given as front line therapy. 25% (2/8) of patients had received treatment prior to EGFRi and 20% (4/9) prior to mTKIs (p = 1). There was no significant difference in mOS with HR 0.6 (95% CI 0.16 - 2.6), p = 0.6. We also compared the mOS of patients who received ICIs (n = 22) with those who did not (n = 346) but there was no significant difference (mOS 3.19 vs 3.17 yrs respectively, HR 0.87, 95% CI 0.47- 1.61, p = 0.65). Conclusions: There was no significant difference in the mOS between pts with R/M ACC who were treated with chemo, EGFRi or TKIs and in those who received ICIs compared to those who did not in our limited patient population. This highlights the need for predictive biomarkers for better patient selection with the goal of personalizing treatment strategies for this disease.