Intermittent MEK inhibition for the treatment of metastatic uveal melanoma

Introduction

Uveal melanoma (UM) is associated with poor outcomes in the metastatic setting and harbors activating mutations resulting in upregulation of MAPK signaling in almost all cases. The efficacy of selumetinib, an oral allosteric inhibitor of MEK1/2, was limited when administered at a continual dosing schedule of 75 mg BID. Preclinical studies demonstrate that intermittent MEK inhibition reduces compensatory pathway activation and promotes T cell activation. We hypothesized that intermittent dosing of selumetinib would reduce toxicity, allow for the administration of increased doses, and achieve more complete pathway inhibition, thus resulting in improved antitumor activity.

Methods

We conducted a phase Ib trial of selumetinib using an intermittent dosing schedule in patients with metastatic UM. The primary objective was to estimate the maximum tolerated dose (MTD) and assess safety and tolerability. Secondary objectives included assessment of the overall response rate (RR), progression-free survival (PFS) and overall survival (OS). Tumor biopsies were collected at baseline, on day 3 (on treatment), and between days 11-14 (off treatment) from 9 patients for pharmacodynamic (PD) assessments.

Results

29 patients were enrolled and received at least one dose of selumetinib across 4 dose levels (DL; DL1: 100 mg BID; DL2: 125 mg BID; DL3: 150 mg BID; DL4: 175 mg BID). All patients experienced a treatment-related adverse event (TRAE), with 5/29 (17%) developing a grade 3 or higher TRAE. Five dose limiting toxicities (DLT) were observed: 2/20 in DL2, 2/5 in DL3, 1/1 in DL4. The estimated MTD was 150 mg BID (DL3), with an estimated probability of toxicity of 29% (90% probability interval 16%-44%). No responses were observed; 11/29 patients achieved a best response of stable disease (SD). The median PFS and OS were 1.8 months (95% CI 1.7, 4.5) and 7.1 months (95% CI 5.3, 11.5). PD analysis demonstrated at least partial pathway inhibition in all samples at day 3, with reactivation between days 11-14 in 7 of those cases.

Conclusions

We identified 150 mg BID as the MTD of intermittent selumetinib, representing a 100% increase over the continuous dose MTD (75 mg BID). However, no significant clinical efficacy was observed using this dosing schedule.

Adjuvant crizotinib in high-risk uveal melanoma following definitive therapy

Introduction

Approximately 40% of patients with uveal melanoma (UM) will develop metastatic disease. Tumors measuring at least 12mm in basal diameter with a class 2 signature, as defined by a widely used gene expression-profiling test, are associated with significantly higher risk of metastasis, with a median time to recurrence of 32 months. No therapy has been shown to reduce this risk.

Materials and Methods

This was a single-arm, multicenter study in patients with high-risk UM who received definitive treatment of primary disease and had no evidence of metastasis. Patients were consecutively enrolled to receive 12 four-week cycles of adjuvant crizotinib at a starting dose of 250mg twice daily and were subsequently monitored for 36 months. The primary outcome of this study was to assess recurrence-free survival (RFS) of patients with high-risk UM who received adjuvant crizotinib.

Results

34 patients enrolled and received at least one dose of crizotinib. Two patients were unevaluable due to early withdrawal and loss to follow-up, leaving 32 patients evaluable for efficacy. Eight patients (25%) did not complete the planned 48-week course of treatment due to disease recurrence (n=5) or toxicity (n=3). All patients experienced at least one adverse event (AE), with 11/34 (32%) experiencing a Common Terminology Criteria for Adverse Events (CTCAE) grade 3 or 4 AE. After a median duration of follow up of 47.1 months, 21 patients developed distant recurrent disease. The median RFS was 34.9 months (95% CI (Confidence Interval), 23-55 months), with a 32-month recurrence rate of 50% (95% CI, 33-67%). Analysis of protein contents from peripheral blood extracellular vesicles in a subset of patient samples from baseline, on-treatment, and off-treatment, revealed a change in protein content associated with crizotinib exposure, however without a clear association with disease outcome.

Conclusions

The use of adjuvant crizotinib in patients with high-risk UM did not result in improved RFS when compared to historical controls. Analysis of blood extracellular vesicles revealed changes in protein content associated with treatment, raising the possibility of future use as a biomarker. Further investigation of adjuvant treatment options are necessary for this challenging disease.

A Phase Ib Study of Sotrastaurin, a PKC Inhibitor, and Alpelisib, a PI3Kα Inhibitor, in Patients with Metastatic Uveal Melanoma

Uveal melanoma (UM) is a rare subset of melanoma characterized by the presence of early initiating GNAQ/11 mutations, with downstream activation of the PKC, MAPK, and PI3Kα pathways. Activity has been observed with the PKC inhibitors sotrastaurin (AEB071) and darovasertib (IDE196) in patients with UM. Inhibition of the PI3K pathway enhances PKC inhibition in in vivo models. We therefore conducted a phase Ib study of sotrastaurin in combination with the PI3Kα inhibitor alpelisib to identify a tolerable regimen that may enhance the activity of PKC inhibition alone. Patients with metastatic uveal melanoma (n = 24) or GNAQ/11 mutant cutaneous melanoma (n = 1) were enrolled on escalating dose levels of sotrastaurin (100-400 mg BID) and alpelisib (200-350 mg QD). The primary objective was to identify the maximum tolerated dose (MTD) of these agents when administered in combination. Treatment-related adverse events (AE) occurred in 86% (any grade) and 29% (Grade 3). No Grade 4-5-related AEs occurred. Dose Level 4 (sotrastaurin 200 mg BID and alpelisib 350 mg QD) was identified as the maximum tolerated dose. Pharmacokinetic analysis demonstrated increasing concentration levels with increasing doses of sotrastaurin and alpelisib, without evidence of interaction between agents. Pharmacodynamic assessment of pMARCKS and pAKT protein expression with drug exposure suggested modest target inhibition that did not correlate with clinical response. No objective responses were observed, and median progression-free survival was 8 weeks (range, 3-51 weeks). Although a tolerable dose of sotrastaurin and alpelisib was identified with pharmacodynamic evidence of target inhibition and without evidence of a corresponding immunosuppressive effect, limited clinical activity was observed.

Observational study of talimogene laherparepvec use in the anti-PD-1 era for melanoma in the US (COSMUS-2)

AIM

Talimogene laherparepvec (T-VEC) is an intralesional therapy for unresectable, metastatic melanoma. T-VEC real-world use in the context of anti-PD1-based therapy requires further characterization.

MATERIALS & METHODS

A retrospective review of T-VEC use from 1 January 2017 and 31 March 2018 for melanoma patients was conducted at seven US institutions.

RESULTS

Among 83 patients, three categories of T-VEC and anti-PD-1 therapy were identified: T-VEC used without anti-PD-1 (n = 29, 35%), T-VEC after anti-PD-1-based therapy (n = 22, 27%) and concurrent T-VEC and anti-PD-1-based therapy (n = 32, 39%). 25% of patients discontinued T-VEC therapy due to no remaining injectable lesions, 37% discontinued T-VEC due to progressive disease. Discontinuation of T-VEC did not differ by anti-PD-1-based therapy use or timing.

CONCLUSION

In real-world settings, T-VEC may be used concurrently with or after anti-PD-1-based therapy.

Abstract CT028: Drug-drug interaction potential of EZH2 inhibitor tazemetostat (TAZ)

TAZ, a selective, oral EZH2 inhibitor, is in the phase 2 clinical investigation stage for the treatment of advanced solid tumors (AdvST) and B-cell non-Hodgkin lymphoma (NHL). Drug-drug interaction (DDI) potential of TAZ was investigated in study EZH-105, a phase 1, open-label, 2-part study in adults with AdvST or NHL. In Part A, patients received TAZ 400 mg twice-daily (BID) days 1-24, then 800 mg BID continuously. Moderate CYP3A inhibitor fluconazole 400 mg was administered once daily (QD) days 16-19. Serial blood samples for pharmacokinetic analysis were collected on days 15 and 19. Patients in Part B received TAZ 800 mg BID continuously starting day 2. The CYP2C8 probe repaglinide 0.25 mg and CYP2C19 probe omeprazole 20 mg were administered on day 1 and 1 hour following TAZ administration on day 16. Omeprazole 20 mg QD continued days 17-19. Serial blood samples were collected on days 1, 16, and 19. DDIs were evaluated based on AUC and Cmax. Other primary endpoints included safety of TAZ. As of August 14, 2018, 27 patients were enrolled (n=17 AdvST, n=10 NHL). Median age was 60 years. Preliminary pharmacokinetic results are displayed in the Table. Median treatment exposure was 70 days in Part A and 57 days in Part B. Two patients, both in Part B, discontinued due to treatment emergent adverse events (TEAEs). Grade ≥3 TEAEs were reported in 12 patients. The most frequent treatment-related TEAEs (any grade) included diarrhea (n=6), fatigue (n=6), and nausea (n=3). In conclusion, the likelihood of a clinically significant DDI in the presence of TAZ is minimal.

Table.Preliminary study EZH-105 PK resultsPart A. The effect of fluconazole on TAZParameterTAZ alone Day 15 Mean (%CV)TAZ + fluconazole Day 19 Mean (%CV)TAZ, n=14Cmax, ng/ml426 (95)968 (80)AUC0-12h, ng*h/mL1590 (81)5180 (66)Part B. The effect of TAZ on REP and OMPREP + OMP Day 1 Mean (%CV)REP + OMP + TAZ Day 16 Mean (%CV)REP, n=12Cmax, ng/ml5 (109)10 (78)AUC0-7h, ng*h/mL9 (110)17 (65)OMP, n=12Cmax, ng/ml263 (266)220 (250)AUC0-7h, ng*h/mL677 (340)558 (231)Part B. The effect of OMP on TAZTAZ prior to OMP Day 16 Mean (%CV)TAZ + OMP Day 19 Mean (%CV)TAZ, n=9Cmax, ng/ml613 (91)663 (68)AUC0-12h, ng*h/mL2200 (58)2820 (62)AUC, area under the concentration curve; CI, confidence interval; Cmax, maximum plasma concentration; CV, coefficient of variation; REP, repaglinide; OMP, omeprazole; PK, pharmacokinetic; TAZ, tazemetostat.

Citation Format: Jennifer E. Amengual, Gary K. Schwartz, Lora Inclan, Abhijeet Kumar, Patricia Robles-Medina, Shahnaz Singh-Kandah, Benjamin Suttle, Melissa Beelen, Daniel Persky. Drug-drug interaction potential of EZH2 inhibitor tazemetostat (TAZ) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT028.

A phase 2 trial of everolimus and pasireotide long-acting release in patients with metastatic uveal melanoma

The aim of this study was to test the hypothesis that inhibiting mammalian target of rapamycin and insulin-like growth factor-1 receptor would be efficacious in metastatic uveal melanoma. This was a phase 2 trial of everolimus 10 mg daily plus pasireotide long-acting release 60 mg every 28 days enrolling patients with progressive, metastatic uveal melanoma to treatment until progression by Response Evaluation Criteria In Solid Tumors 1.1 (RECIST 1.1) or unacceptable toxicity. The primary endpoint was clinical benefit rate, defined as any objective response or RECIST 1.1 stable disease at 16 weeks. A subset of patients underwent baseline indium-111-octreotide scans. A total of 14 patients were enrolled, of which 13 were evaluable for the primary endpoint, before the study was terminated due to poor accrual. Three of 13 (26%) patients obtained clinical benefit. Seven of 13 (54%) had stable disease lasting for a median of 8 weeks (range: 8-16 weeks). Grade 3 adverse events deemed at least possibly related to study drugs were hyperglycemia (n=7), oral mucositis (n=2), diarrhea (n=1), hypophosphatemia (n=1), and anemia (n=1). Seven of 14 (50%) patients required at least one dose reduction due to toxicity. Seven of eight (88%) patients with baseline indium-111-octreotide scans had at least one avid lesion, with significant intrapatient heterogeneity. There was a trend toward an association between octreotide avidity and cytostatic response to therapy (P=0.078). The combination of everolimus and pasireotide has limited clinical benefit in this small metastatic uveal melanoma cohort. Dose reductions for side effects were common. Further investigation into the relationship between somatostatin receptor expression and cytostatic activity of somatostatin analogues is warranted.

Langerhans-type dendritic cells electroporated with TRP-2 mRNA stimulate cellular immunity against melanoma: Results of a phase I vaccine trial

Purpose: We conducted a phase I vaccine trial to determine safety, toxicity, and immunogenicity of autologous Langerhans-type dendritic cells (LCs), electroporated with murine tyrosinase-related peptide-2 (mTRP2) mRNA in patients with resected AJCC stage IIB, IIC, III, or IV (MIa) melanoma. Experimental Design: Nine patients received a priming immunization plus four boosters at three week intervals. Vaccines comprised 10 × 10⁶ mRNA-electroporated LCs, based on absolute number of CD83⁺CD86^brightHLA-DR^brightCD14^neg LCs by flow cytometry. Initial vaccines used freshly generated LCs, whereas booster vaccines used viably thawed cells from the cryopreserved initial product. Post-vaccination assessments included evaluation of delayed-type hypersensitivity (DTH) reactions after booster vaccines and immune response assays at one and three months after the final vaccine. Results: All patients developed mild DTH reactions at injection sites after booster vaccines, but there were no toxicities exceeding grade 1 (CTCAE, v4.0). At one and three months post-vaccination, antigen-specific CD4 and CD8 T cells increased secretion of proinflammatory cytokines (IFN-γ, IL-2, and TNF-α), above pre-vaccine levels, and also upregulated the cytotoxicity marker CD107a. Next-generation deep sequencing of the TCR-V-β CDR3 documented fold-increases in clonality of 2.11 (range 0.85-3.22) for CD4 and 2.94 (range 0.98-9.57) for CD8 T cells at one month post-vaccines. Subset analyses showed overall lower fold-increases in clonality in three patients who relapsed (CD4: 1.83, CD8: 1.54) versus non-relapsed patients (CD4: 2.31, CD8: 3.99). Conclusions: TRP2 mRNA-electroporated LC vaccines are safe and immunogenic. Responses are antigen-specific in terms of cytokine secretion, cytolytic degranulation, and increased TCR clonality, which correlates with clinical outcomes.

Phase 2 trial of the novel multi-receptor tyrosine kinase inhibitor sitravatinib in well-differentiated/dedifferentiated liposarcoma

TPS11082

Background: Well-differentiated/dedifferentiated liposarcoma (WD/DD LPS) is a sarcoma subtype of adipocytic origin characterized by amplification of cyclin dependent kinase 4 (CDK4) and MDM2. WD/DD LPS is resistant to chemotherapy and success with CDK4 inhibitors is limited. We recently characterized the landscape of activated receptor tyrosine kinases (RTKs) and intracellular signaling pathways finding marked heterogeneity by sarcoma subtype [Patwardhan et al. Oncotarget 2016;7(4)]. In WD/DD LPS cell lines, phosphorylated (p) IGF1-R, MET and PDGFRb are strongly expressed. Selective siRNA knockdown of expression of 1 or more of these RTKs inhibited growth of WD/DD LPS cell lines. Sitravatinib (S) is a novel inhibitor of a broad panel of related RTKs. We showed that S abrogates expression of p-RTKs, including IGF1-R, MET and PDGFRb, at low nanomolar concentrations and potently inhibits proliferation of WD/DD LPS cell lines, where anti-proliferative effects of S were superior to other RTK inhibitors including imatinib, crizotinib and pazopanib. S suppressed tumor growth in vivo in WD/DD LPS . A phase 1 trial of S in solid tumors showed clinical activity in WD/DD LPS. Recommended phase 2 dose was 150 mg/day. As there are no approved RTK inhibitors for adipocytic sarcomas, and based on these findings, we initiated a phase 2 trial of S in WD/DD LPS. Methods: This is a single-arm open-label multi-center Simon 2 stage phase II trial of S in 29 patients (pts) with advanced WD/DD LPS who failed 1 prior therapy and show disease progression before enrollment. Pts receive S 150 mg orally daily continuously. Primary endpoint is the progression free rate at 12 weeks (PFR12) versus historical controls. The design has power of 85% to show improvement in PFR12 from 20% (inactive) to 40% (active) with α = 0.10. Secondary endpoints are ORR, PFS and safety. A subset of pts undergo baseline and on-treatment biopsies and reverse phase protein array used to measure changes in expression of p-RTKs and signaling pathway proteins with confirmation by immunoblot. Genomic landscape of these tumors will be analyzed by next generation sequencing. The study opened in 1/2017. Clinical trial information: NCT02978859.

Multi-center phase Ib study of intermittent dosing of the MEK inhibitor, selumetinib, in patients with advanced uveal melanoma not previously treated with a MEK inhibitor

TPS9597

Background: Uveal melanoma (UM) is a rare subtype of melanoma with no effective therapy for advanced disease. UM is characterized by mutations in GNAQ and GNA11 leading to constitutive activation of the mitogen activated protein kinase (MAPK) pathway. We have previously shown that targeting the MAPK pathway though MEK inhibition with Selumetinib (AZD6244, ARRY-142886) using a continuous dosing schedule improved progression free survival (PFS) in a randomized Phase II study of Selumetininb versus chemotherapy in patients with metastatic UM; however, no PFS or overall survival (OS) benefit was observed in a subsequent randomized Phase III study of Selumetinib and chemotherapy versus chemotherapy alone. We hypothesize that an intermittent dosing schedule of Selumetinib may be more effective than continuous dosing by achieving higher dose levels, better drug tolerability, and more complete target inhibition. We propose a Phase Ib study of Selumetinib in UM using an intermittent dosing schedule. Methods: A total of 28 subjects will be enrolled using the time to event continual reassessment method (TITE-CRM). Key inclusion criteria include a diagnosis of advanced UM, measurable disease by RECIST v1.1, and no prior MEK inhibitor therapy. Eligible subjects will be treated with Selumetinib starting at a dose level of 125 mg orally twice a day, using a 3-days-on and 4-days-off per week schedule. The primary goal of this study is to estimate the maximum tolerated dose (MTD) of intermittently dosed Selumetinib. Secondary endpoints are response rate, PFS and OS. Responses will be evaluated every 8 weeks by a CT scan of the chest and CT or MRI of the abdomen/ pelvis using RECIST v1.1 criteria. Mandatory tumor biopsies will be obtained at baseline, cycle 1 day 3 (Selumetinib-on day), and between cycle 1 day 11-14 (Selumetinib-off day) in 20 subjects, and optionally at progression. Tumor tissue will be assessed for MAPK pathway inhibition and reactivation at each time point, as well as mechanisms of resistance. Recruitment is currently ongoing. Clinical trial information: NCT02768766.