Combining Tumor Vaccination and Oncolytic Viral Approaches with Checkpoint Inhibitors: Rationale, Pre-Clinical Experience, and Current Clinical Trials in Malignant Melanoma.

The field of tumor immunology has faced many complex challenges over the last century, but the approval of immune checkpoint inhibitors (anti-cytotoxic T-lymphocyte-associated protein 4 [CTLA4] and anti-programmed cell death-1 [PD-1]/PD-ligand 1 [PD-L1]) and talimogene laherparepvec (T-VEC) for the treatment of metastatic melanoma have awakened a new wave of interest in cancer immunotherapy. Additionally, combinations of vaccines and oncolytic viral therapies with immune checkpoint inhibitors and other systemic agents seem to be promising synergistic strategies to further boost the immune response against cancer. These combinations are undergoing clinical investigation, and if successful, will hopefully soon become available to patients. Here, we review key basic concepts of tumor-induced immune suppression in malignant melanoma, the historical perspective around vaccine development in melanoma, and advances in oncolytic viral therapies. We also discuss the emerging role for combination approaches with different immunomodulatory agents as well as new developments in personalized immunization approaches.

Combining an Aurora Kinase Inhibitor and a Death Receptor Ligand/Agonist Antibody Triggers Apoptosis in Melanoma Cells and Prevents Tumor Growth in Preclinical Mouse Models.

PURPOSE: Preclinical studies show that inhibition of aurora kinases in melanoma tumors induces senescence and reduces tumor growth, but does not cause tumor regression. Additional preclinical models are needed to identify agents that will synergize with aurora kinase inhibitors to induce tumor regression. EXPERIMENTAL DESIGN: We combined treatment with an aurora kinase A inhibitor, MLN8237, with agents that activate death receptors (Apo2L/TRAIL or death receptor 5 agonists) and monitored the ability of this treatment to induce tumor apoptosis and melanoma tumor regression using human cell lines and patient-derived xenograft (PDX) mouse models. RESULTS: We found that this combined treatment led to apoptosis and markedly reduced cell viability. Mechanistic analysis showed that the induction of tumor cell senescence in response to the AURKA inhibitor resulted in a decreased display of Apo2L/TRAIL decoy receptors and increased display of one Apo2L/TRAIL receptor (death receptor 5), resulting in enhanced response to death receptor ligand/agonists. When death receptors were activated in senescent tumor cells, both intrinsic and extrinsic apoptotic pathways were induced independent of BRAF, NRAS, or p53 mutation status. Senescent tumor cells exhibited BID-mediated mitochondrial depolarization in response to Apo2L/TRAIL treatment. In addition, senescent tumor cells had a lower apoptotic threshold due to decreased XIAP and survivin expression. Melanoma tumor xenografts of one human cell line and one PDX displayed total blockage of tumor growth when treated with MLN8237 combined with DR5 agonist antibody. CONCLUSIONS: These findings provide a strong rationale for combining senescence-inducing therapeutics with death receptor agonists for improved cancer treatment.

Trametinib in the treatment of melanoma.

INTRODUCTION: Aberrant MAPK pathway signaling is a hallmark of melanoma. Mitogen/extracellular signal-regulated kinase (MEK) 1/2 are integral components of MAPK signaling. Several MEK inhibitors have demonstrated activity as single agents and in combination with other therapies. Trametinib was the first MEK inhibitor approved for use in treatment of advanced BRAF(V600) mutant melanoma as a single agent and in combination with BRAF inhibitor, dabrafenib. AREAS COVERED: In this article, we discuss the underlying biology of MEK inhibition and its rationale in melanoma treatment with special emphasis on the clinical development of trametinib, from initial Phase I studies to randomized Phase II and III studies, both as monotherapy and in combination with other therapeutics. Furthermore, we briefly comment on trametinib for NRAS mutant and other non-BRAF mutant subsets of melanoma. EXPERT OPINION: Trametinib is a novel oral MEK inhibitor with clinical activity in BRAF(V600) mutant metastatic melanoma alone and in combination with dabrafenib. Trametinib is currently being explored in other genetic subsets as well, particularly those with NRAS mutations or atypical BRAF alterations. Furthermore, to maximize efficacy and overcome acquired resistance, studies evaluating the combination of trametinib with other targeted agents and immunotherapy are underway.

Randomized phase II trial of sorafenib with temsirolimus or tipifarnib in untreated metastatic melanoma (S0438).

PURPOSE: Signaling pathway stimulation by activating mutations of oncogenes occurs in most melanomas and can provide excellent targets for therapy, but the short-term therapeutic success is limited by intrinsic and acquired resistance. The mitogen-activated protein kinase and phosphoinositide 3-kinase/AKT/mTOR pathways are activated in most cutaneous melanomas. The purpose of this trial was to prospectively evaluate 2 molecularly targeted drug combinations in patients with untreated metastatic melanoma. EXPERIMENTAL DESIGN: This randomized phase II study enrolled patients between May 2008 and November 2009 with nonocular melanoma, no prior systemic chemotherapy, and no history of brain metastasis. Arm A received oral sorafenib 200 mg twice daily plus i.v. temsirolimus 25 mg weekly; and arm B received oral sorafenib 400 mg every morning, 200 mg every night daily plus oral tipifarnib 100 mg twice daily, 3 weeks of every 4. The primary objectives were to evaluate progression-free survival (PFS), objective response rate, and toxicity for the 2 regimens. RESULTS: On arm A (63 evaluable patients), the median PFS was 2.1 months and median overall survival (OS) was 7 months. Three patients achieved partial response (PR). Thirty-nine evaluable patients were accrued to arm B, which closed after first-stage accrual; the median PFS was 1.8 months and OS was 7 months, with 1 patient achieving PR. CONCLUSIONS: The combinations of molecularly targeted agents tested did not show sufficient activity to justify further use. Newer agents and improved patient selection by characterization of the molecular targets in individual tumors show great promise and should be incorporated into future studies, along with appropriate laboratory correlates.

Retrospective analysis of the safety and efficacy of interleukin-2 after prior VEGF-targeted therapy in patients with advanced renal cell carcinoma.

Agents targeting vascular endothelial growth factor (VEGF) signaling have been advocated as frontline therapy for advanced renal cancer. The role of interleukin 2 (IL-2) therapy after resistance to VEGF-targeted therapy remains unexplored. We conducted a retrospective analysis of the tolerability and efficacy of IL-2 therapy in patients who had previously received VEGF-targeted therapy. Twenty-three consecutive patients who received salvage IL-2 therapy were analyzed. Fifteen patients had received prior tyrosine kinase inhibitors (TKIs) (sorafenib or sunitinib), whereas 8 patients had received bevacizumab alone. Six of 23 patients did not receive week 2 of cycle 1 of treatment. All 6 of these patients had received prior TKIs. The incidence of severe cardiac toxicities, including 1 sudden cardiac death, in patients receiving prior TKI was 40% (95% confidence interval, 16.3-67.7%), significantly higher than what is expected from historical experience. Only 1 of 23 patients proceeded to receive a second cycle of IL-2. No patients achieved a partial or complete response to therapy. This retrospective analysis highlights unexpected and severe cardiac toxicities in patients receiving IL-2 after VEGF-targeted TKI therapy. The assumption that IL-2 therapy can be safely administered after TKI therapy may not be valid. Further examination of the safety of this sequential approach is necessary and more cautious patient selection seems warranted.

Double-blind randomized phase II study of the combination of sorafenib and dacarbazine in patients with advanced melanoma: a report from the 11715 Study Group.

PURPOSE: This phase II study evaluated the efficacy and safety of sorafenib plus dacarbazine in patients with advanced melanoma. PATIENTS AND METHODS: This randomized, double-blind, placebo-controlled, multicenter study enrolled chemotherapy-naive patients with stage III (unresectable) or IV melanoma. A total of 101 patients received placebo plus dacarbazine (n = 50) or sorafenib plus dacarbazine (n = 51). On day 1 of a 21-day cycle, patients received intravenous dacarbazine 1,000 mg/m(2) for a maximum of 16 cycles. Oral sorafenib 400 mg or placebo was administered twice a day continuously. The primary end point was progression-free survival (PFS) by independent assessment. Secondary and tertiary end points included time to progression (TTP), response rate, and overall survival (OS). RESULTS: Median PFS in the sorafenib plus dacarbazine arm was 21.1 weeks versus 11.7 weeks in the placebo plus dacarbazine arm (hazard ratio [HR], 0.665; P = .068). There were statistically significant improvements in PFS rates at 6 and 9 months, and in TTP (median, 21.1 v 11.7 weeks; HR, 0.619) in favor of the sorafenib plus dacarbazine arm. No difference in OS was observed (median, 51.3 v 45.6 weeks in the placebo plus dacarbazine and sorafenib plus dacarbazine arms, respectively; HR, 1.022). The regimen was well tolerated and had a manageable toxicity profile. CONCLUSION: Sorafenib plus dacarbazine was well tolerated in patients with advanced melanoma and yielded an encouraging improvement in PFS. Based on these findings, additional studies with the combination are warranted in this patient population.