Clinical outcomes of advanced stage cancer patients treated with sequential immunotherapy in phase 1 clinical trials.

Background Given the increasing number of available immunotherapeutic agents, more patients are presenting after failing immunotherapy in need of new treatment options. In this study, we investigated the clinical outcomes of patients treated with sequential immunotherapy. Methods We performed a retrospective review of 90 advanced stage cancer patients treated on immunotherapy-based phase 1 clinical trials at Winship Cancer Institute from 2009 to 2017. We included 49 patients with an immune checkpoint inhibitor (ICI)-indicated histology. Patients were analyzed based on whether they had received prior ICI. Clinical outcomes were overall survival (OS), progression-free survival (PFS), and clinical benefit (best response of complete response, partial response, or stable disease). Univariate analysis (UVA) and multivariate analysis (MVA) were performed using Cox proportional hazard or logistic regression model. Covariates included age, liver metastases, number of prior lines of therapy, histology, and Royal Marsden Hospital (RMH) risk group. Results The most common histologies were melanoma (61%) and lung/head and neck cancers (37%). More than half of patients (n = 27, 55%) received at least one ICI prior to trial enrollment: ten received anti-PD-1, two received anti-CTLA-4, five received anti-PD-1/CTLA-4 combination, and ten received multiple ICI. In MVA, ICI-naïve patients had significantly longer OS (HR: 0.22, CI: 0.07-0.70, p = 0.010) and trended towards higher chance of CB (HR: 2.52, CI: 0.49-12.97, p = 0.268). Patients who received prior ICI had substantially shorter median OS (10.9 vs 24.3 months, p = 0.046) and PFS (2.8 vs. 5.1 months, p = 0.380) than ICI-naïve patients per Kaplan-Meier estimation. Within the ICI-naïve group, 78% (7 of 9) of patients who received prior interleukin (IL-2) or interferon gamma (IFNγ) experienced disease control for at least 6 months, compared to a disease control rate of 15% (2 of 13) in patients who had received chemotherapy, targeted therapy, or no prior treatment. Conclusions ICI-naïve patients may experience improved clinical outcomes on immunotherapy-based phase 1 clinical trials than patients who have received prior ICI. This may be particularly true for patients who received prior IL-2 or IFNγ. Further development of immunotherapy combination therapies is needed to improve clinical outcomes of these patients. These results should be validated in a larger study.