Javed, Asad

Abstract Background Pembrolizumab is approved for advanced cutaneous melanoma (aCM). Cabozantinib, an oral multi‐tyrosine kinase inhibitor, has demonstrated antitumor activity as monotherapy or in combination with anti‐PD‐1 therapy in malignancies. The objective of this study was to determine the safety and efficacy of cabozantinib and pembrolizumab for patients with aCM. Methods This phase 1b/2 study enrolled 28 patients with unresectable aCM. In phase 1b, escalating dose levels of cabozantinib (20 mg, 40 mg, and 60 mg) were administered concurrently with pembrolizumab 200 mg intravenously every 3 weeks using a 3 + 3 design to determine recommended phase 2 dose (RP2D). In phase 2, patients received cabozantinib at RP2D in combination with pembrolizumab using a Simon 2 stage design. Primary end point of phase 2 was overall response rate (ORR). Secondary end points included disease control rate, progression‐free survival (PFS), and overall survival (OS). Results Phase 1b enrolled eight patients, cabozantinib 40 mg daily dose level was selected as RP2D. Response rate in stage 1 exceeded predefined criteria for proceeding to expansion phase; however, phase 2 was terminated after 20 patients due to low accrual in the setting of evolving standard of care. Among all treated patients, the most common grade ≥3 toxicities were hypertension ( n = 10, 36%), hypokalemia ( n = 5, 18%), hypophosphatemia ( n = 4, 14%), and ALT elevation ( n = 4, 14%). Among 20 patients treated in phase 2, ORR was 45%, median PFS was 6.6 months, and median OS was 29.5 months. Conclusions Cabozantinib and pembrolizumab combination was explored in treatment‐naive aCM. Toxicity was consistent with known profiles, but discontinuation rates were notable.

9538 Background: Uveal melanoma has a poor prognosis following metastasis to the liver. Immune checkpoint inhibitors (ICIs) are often utilized in patients with metastatic uveal melanoma (MUM); however, ICIs in MUM have low response rates. We studied the association of immune infiltrates in MUM liver metastases with survival outcomes for all patients, in addition to evaluating if immune infiltrates improve survival for patients treated with ICIs. Methods: We included MUM patients with liver metastases who had pre-treatment liver biopsies available at Mayo Clinic Rochester. Demographics, disease characteristics, treatments, and clinical outcomes were obtained from the electronic medical record. Core biopsies of liver metastases were reviewed for the presence of lymphocytes at interface of the tumor and liver parenchyma, and for tumor-infiltrating lymphocytes (TILs). If TILs were present, then additional immunohistochemistry (IHC) staining was performed for CD3, CD4, CD8, PD1, CD25, and FoxP3. Overall survival (OS) was estimated with the Kaplan-Meier method and compared between groups with Cox proportional hazards regression. Median OS and hazard ratios (HR) were calculated and p-values (p) <0.05 were considered statistically significant. Results: 140 patients with MUM who had pre-treatment liver biopsies were identified. 122 biopsies were evaluable for the presence of lymphocytes, either at the tumor-liver interface, or for TILs. 80/122 (65.6%) biopsies showed presence of any lymphocyte and 27/80 had TILs. 27 biopsies had sufficient tissue for further IHC classification. CD8+ T cells were identified in 27/27 samples, T cell PD1 positivity ≥1% in 4/27 samples, and regulatory T cell markers (CD25 and/or FoxP3) in 18/27 samples. Median OS for the entire cohort was 16 months (mo). Patients still alive at the time of data analysis had at least one year of follow-up available (range 13-124 mo). Univariate analyses (UVA) showed no significant improvement in OS based on the presence of any lymphocytes (HR 1.01, p 0.98), lymphocytes at the tumor-liver interface (HR 1.10, p 0.64), TILs (HR 0.78, p 0.27), >50% CD8+ T cells (HR 0.88, p 0.77), or absence of FoxP3+ T cells (HR 0.68, p 0.40). In the 69 patients treated with ICIs (pembrolizumab, nivolumab, or ipilimumab plus nivolumab), neither the presence of any lymphocytes (HR 1.19, p 0.56) nor TILs (HR 0.68, p 0.24) were associated with an OS benefit. Conclusions: We present a large cohort of patients with MUM where we characterized immune infiltrates in liver metastases and evaluated clinical outcomes. OS did not significantly improve with the presence of any lymphocytes, TILs, CD8+ T cells, or with the absence of FoxP3+ T cells. These results were consistent across all patients whether they were treated with ICIs or not. Our findings suggest that lymphocytes in MUM are functionally dormant and highlights the need for novel immune-activating treatment strategies.

e22052 Background: Metastatic Uveal Melanoma (MUM) is a rare tumor with poor prognosis following development of liver metastasis. We hypothesized that patterns of metastasis in Uveal Melanoma correlate with clinical outcomes. Methods: We retrospectively reviewed patients with MUM at Mayo Clinic, Rochester from January 1999 to August 2019. Patients were stratified into two groups based on the pattern of hepatic and pulmonary metastasis at the time of diagnosis of metastatic disease: Group 1 (≤5 liver metastasis or lung metastasis) and Group 2 ( > 5 liver metastasis without lung metastasis). Baseline characteristics were compared between both groups. Survival analysis was performed using the Kaplan Meier method. Univariate and multivariate analysis were performed for Overall Survival (OS). Results: 147 patients were included in the study (n = 67 Group 1; n = 80 Group 2). In Group 1, 49/67 patients presented with ≤5 liver metastasis and 18/67 had lung metastasis without liver metastasis. Median OS for Group 1 was significantly longer than Group 2 (38 vs. 15 months; p < 0.0001) (Table). On univariate analysis, predictors for OS were: Pattern of Metastasis, ECOG PS > 0, Time to metastasis > 60 months, and Surgical metastatectomy. Pattern of Metastasis was an independent predictor for OS in a multivariate model that included these predictors (p = 0.0004). Group 1 patients were more likely to undergo surgical metastatectomy compared to group 2 (21.5% vs. 1.3%; p < 0.0001). Interestingly, the median time to metastasis from diagnosis of UM was significantly longer for Group 1 as compared to Group 2 (67 vs. 24.5 months; p < 0.0001). Conclusions: Limited (≤5) liver metastasis or lung metastasis (without liver metastasis) at diagnosis predict favorable clinical outcomes in MUM. The occurrence of such metastasis following a significantly longer time from primary diagnosis suggests the existence of a distinct sub-type of metastatic disease with relatively indolent behavior. [Table: see text]

Objectives:With the introduction of novel immune therapeutics for the treatment of disseminated malignancies, we sought to evaluate whether deliberate sequencing of immunotherapy before/after conventional cytotoxic chemotherapy would have an impact on clinical outcomes in patients with previously treated metastatic melanoma. We sought to evaluate whether or not ipilimumab immunotherapy administered before or after cytotoxic chemotherapy (nab-paclitaxel+bevacizumab, AB) would impact clinical outcomes.Methods:We conducted a randomized phase 2 clinical trial of patients with BRAF wild-type metastatic melanoma (up to 2 prior therapies) who received either: (A) AB followed by ipilimumab therapy at progression; or (B) ipilimumab followed by AB treatment at progression. The primary goal of the study was a comparison of AB versus ipilimumab progression-free survival, with secondary clinical and laboratory endpoints.Results:This study did not reach full accrual due to concurrent Food and Drug Administration approval of anti-programmed cell death 1 agents. Nevertheless, the available data suggests a cumulative therapeutic advantage to the sequential use of ipilimumab followed by AB. Correlative laboratory data revealed a favorable effect on systemic immune homeostasis in patients receiving AB therapy, of potential interest in further investigations, especially in the context of chemotherapy/immunotherapy combinations.Conclusion:Albeit limited in scope, our data suggest that cytotoxic therapy with nab-paclitaxel and bevacizumab appear to favorably alter systemic parameters of immune function of potential benefit in combination T-cell directed immune checkpoint inhibitor therapy.