Phase Ib study of MIW815 (ADU-S100) in combination with spartalizumab (PDR001) in patients (pts) with advanced/metastatic solid tumors or lymphomas

2507

Background: MIW815 (ADU-S100) is a novel synthetic cyclic dinucleotide that activates the STimulator of INterferon Genes (STING) pathway impacting tumor cells, tumor microenvironment, vasculature, tumor-associated fibroblasts, and priming APC and CD8+ T cells. Spartalizumab is a humanized IgG4 mAb that blocks the binding of PD-1 to PD-L1/2. Preclinical data support synergistic antitumor effects when MIW815 (ADU-S100) is combined with checkpoint inhibitors. Methods: In this Phase Ib dose escalation study, pts with advanced/metastatic solid tumors or lymphoma received MIW815 (ADU-S100) (intratumoral injections [50–800 µg] either weekly [3 weeks on/1 week off] or Q4W) and spartalizumab (400 mg IV Q4W). Injected and non-injected tumor biopsies were obtained at baseline and on treatment. Primary objectives are to determine safety and identify a dose/schedule for future studies. Preliminary activity, pharmacokinetics (PK), and pharmacodynamics (PD) are also being explored. Results: As of Jan 11, 2019, 66 pts (median age: 61 y) with various solid tumors or lymphomas have been treated. Treatment was discontinued in 49 pts (74%) due to disease progression (n = 28), pt/physician decision (n = 18), AE (n = 2), or death (n = 1). No DLTs were reported during the first cycle at any dose level. Most common (≥5 pts) treatment-related AEs (TRAEs) were injection site pain (12%), pyrexia (11%), and diarrhea (9%). Grade 3/4 TRAEs (in ≥2 pts) were increased AST and ALT (3% each). Serious TRAEs were pyrexia (3%), increased amylase, increased lipase, diarrhea, fatigue, hyperthyroidism, partial seizures, dyspnea, and pneumonitis (all 2%). Partial responses in pts with PD-1–naive TNBC and PD-1–relapsed/refractory melanoma have been observed. MIW815 (ADU-S100) plasma exposure generally increased in a dose-dependent manner with a rapid terminal half-life. Response data, PK and PD analyses will be presented. Conclusions: Thus far, MIW815 (ADU-S100) + spartalizumab has demonstrated antitumor activity in PD-1–naive TNBC and PD-1–relapsed/refractory melanoma. The combination is well tolerated, with no DLTs reported to date. The MTD has not been reached and dose escalation is ongoing. Clinical trial information: NCT03172936.

A phase I study evaluating COM701 in patients with advanced solid tumors

TPS2657

Background: There is a high unmet medical need for the treatment (tx) of patients (pt) who are refractory to or relapse following tx with checkpoint inhibitors. Newer checkpoint therapies with novel mechanisms of action that can activate T cells and demonstrate antitumor activity in this pre-tx pt population are urgently needed. COM701 is a novel first-in-class humanized IgG4 monoclonal antibody that binds with high affinity to PVRIG (poliovirus receptor related immunoglobulin domain containing) blocking its interaction with its ligand, PVRL2. Both PVRIG and PVRL2 are part of the DNAM axis as are TIGIT and PD1. Inhibition of PVRIG leads to enhanced activation of T and NK cells, and PVRIG results in tumor growth inhibition in mouse tumor models. We hypothesize that COM701 will demonstrate antitumor activity in pts who are checkpoint inhibitor pre-tx. Methods: NCT03667716 is an ongoing open-label first-in-human phase 1 study in pts with advanced solid tumors. The initial part of this study (Arm A) will evaluate escalating doses of COM701 monotherapy IV Q3 weekly with single pt cohorts for the initial 4 and then 3+3 design. Key Inclusion Criteria: Age ≥18 yrs, histologically confirmed locally advanced/ metastatic solid malignancy and has exhausted available standard therapy, ECOG 0-1, prior anti-PD-1, anti-PD-L1, anti-CTLA-4, OX-40, CD137 permissible. Key Exclusion Criteria: Active autoimmune disease requiring systemic therapy in the last 2 years, symptomatic interstitial or inflammatory lung disease, untx or symptomatic central nervous system metastases. Primary objectives are safety and tolerability of COM701 as measured by the incidence of adverse events (AEs) and dose-limiting toxicities (21-day DLT window), pharmacokinetics of COM701, and to identify the maximum tolerated dose and/or the recommended dose for expansion. Secondary objectives are to characterize the immunogenicity and preliminary antitumor activity of COM701. Statistical Considerations: AEs graded as per CTCAE v4.03, responses as per RECIST v1.1. The analyses of all study objectives will be descriptive and hypothesis generating. No DLTs have been observed in the single pt cohorts. Assessment of pts enrolled into cohort 5 is ongoing at the time of this submission. Clinical trial information: NCT03667716.

Pembrolizumab versus placebo as adjuvant therapy in resected high-risk stage II melanoma: Phase 3 KEYNOTE-716 study

TPS9596

Background: Adjuvant pembrolizumab showed significantly longer recurrence-free survival than placebo in patients with resected stage III melanoma in the KEYNOTE-054 study. KEYNOTE-716 (NCT03553836) is a randomized, placebo-controlled, double-blind, multicenter phase 3 study of adjuvant pembrolizumab in patients with surgically resected high-risk stage II melanoma. Methods: Key eligibility criteria are age ≥12 y with newly diagnosed, completely resected stage IIB/IIC cutaneous melanoma, defined by the AJCC Cancer Staging Manual, 8th edition (wide excision and negative sentinel lymph node biopsy with no evidence of distant metastasis). Patients with mucosal or uveal melanoma or prior treatment (including radiation) for melanoma beyond resection of primary disease within 12 wk of the start of study treatment were excluded. In this 2-part study, in the double-blind phase (part 1), patients will be randomly assigned 1:1 to receive pembrolizumab 200 mg for patients ≥18 y or 2 mg/kg for patients ≥12 y to < 18 y (maximum dose, 200 mg) or placebo every 3 wk for 17 cycles. Study treatment will begin within 12 wk of complete resection. Tumor imaging will be performed every 24 wk while treatment is ongoing, at the end of treatment, every 6 mo for the first 3 y off treatment, and then yearly for up to 2 y or until recurrence (up to 5 y of total imaging). Adverse events will be recorded until 30 d after treatment end (90 d for serious AEs) and graded per National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0. In the unblinded phase (part 2), patients with confirmed recurrence may be rechallenged (patients received pembrolizumab in part 1) or crossed over to pembrolizumab (patients received placebo in part 1). Resected local or distant recurrence or unresectable disease will be treated for an additional 17 or 35 cycles, respectively. Tumor imaging in part 2 will occur every 12 wk during treatment. The primary end point is recurrence-free survival; secondary end points are distant metastasis-free survival, overall survival, and safety. Approximately 954 patients will be enrolled. Clinical trial information: NCT03553836.

Immunobiology, preliminary safety, and efficacy of CPI-006, an anti-CD73 antibody with immune modulating activity, in a phase 1 trial in advanced cancers

2505

Background: CPI-006 inhibits CD73, a nucelotidase that converts AMP to adenosine and functions as a lymphocyte adhesion molecule. CPI-006 is a humanized IgG1 FcγR binding-deficient antibody that binds to CD73+ T and B lymphocytes leading to activation of B cells and expression of CD69. This study investigates the immunobiology, safety, and efficacy of CPI-006 monotherapy and in combination with CPI-444, an adenosine A2A receptor (A2AR) antagonist (NCT03454451). Methods: Patients with relapsed solid tumors were treated in a 3 + 3 escalation study with 1, 3, 6 or 12 mg/kg CPI-006 (Q3w IV infusion) monotherapy or in combination with CPI-444 (100 mg, PO, BID). Flow cytometry was performed on blood samples for lymphocyte subset analysis and receptor occupancy. Results: 17 patients were enrolled; 11 monotherapy and 6 combination. CPI-006 was associated with Grade 1 infusion reactions occuring within 30 minutes of the first infusion and were eliminated by premedication with non-steroidals. No DLTs with monotherapy or combination therapy were seen. Receptor occupancy on peripheral lymphocytes was maintained for the full dosing interval at 12 mg/kg. Pharmacodynamic effects suggesting immune modulation were observed within 1 hr of infusion at all dose levels and included a decrease in peripheral blood CD73pos B cells (mean reduction 86%, p < 0.05), increased CD73neg CD4 T cells (mean increase 37%, p < 0.01), and decreased CD8 T cells (mean reduction 20%, p < 0.01) compared to baseline. Overall, CD4:CD8 ratios were increased. Tumor regression was observed in a prostate cancer patient after 5 cycles of monotherapy at 6 mg/kg; peripheral B cells partially returned by the second cycle and reached a new homeostatic level through subsequent cycles. No change in serum immunoglobulins were observed. Conclusions: CPI-006 induces a rapid lymphocyte redistribution, including a transient reduction of circulating CD73pos B cells suggesting redistribution to lymphoid tissues, and an increased CD4:CD8 ratio, consistent with increased TH effector/memory cells in the blood. The treatment has been well-tolerated, and there is early evidence of anti-tumor activity of CPI-006 monotherapy. Clinical trial information: NCT03454451.

First-in-human phase 1 study of ABBV-085, an antibody-drug conjugate (ADC) targeting LRRC15, in sarcomas and other advanced solid tumors

3004

Background: ABBV-085 is an ADC (conjugated to monomethyl auristatin E, drug:antibody ratio of 2:1) directed against leucine-rich repeat containing 15 (LRRC15), a type 1 transmembrane protein highly expressed on the surface of sarcomas and cancer-associated fibroblasts in stroma of many other cancers. ABBV-085 induced antitumor activity in both in vitro and xenograft models of sarcoma. This phase 1, first-in-human, 2-part study assessed the safety/tolerability of ABBV-085 in patients (pts) with advanced solid tumors (NCT02565758). Methods: Eligible pts (≥18 yr; advanced solid tumors) received ABBV-085 intravenously in a 3+3 dose-escalation (DE) design; 0.3- to 4.8-mg/kg doses every 2 wk (8 cohorts). Pharmacokinetics (PK) were assessed in cycle 1 and cycle 3. Results: As of Dec 2018, 78 pts were enrolled in monotherapy DE and dose-expansion (EXP) cohorts (≤2.7 mg/kg, n = 21; 3.6 mg/kg, n = 45; 4.2 mg/kg, n = 6; 4.8 mg/kg, n = 6); median age: 58 yr (range 21–84); median treatment (Tx) duration: 6.2 wk (range 0.3–54.4). Overall, 77 (98.7%) pts reported ≥1 Tx-emergent adverse events (TEAEs). Fatigue (48.7%) was most common; 19 (24.4%) pts reported grade 1/2 blurred vision (reversible on study discontinuation). Grade ≥3 TEAEs were reported in 56 (71.8%) pts; anemia (14.1%) was the most common. Dose-limiting toxicities occurred at 3.6 mg/kg (n = 1; anemia), 4.2 mg/kg (n = 1; hypertriglyceridemia), and 4.8 mg/kg (n = 2; ileus and nausea); 3.6 mg/kg was chosen as the recommended phase 1b dose (RP1bD). PK exhibited dose-proportional increase in the area under the curve after single-dose administration; half-life was 2.84 days at the RP1bD. Of the 27 sarcoma pts (DE [n = 8]/EXP [n = 19] cohorts; undifferentiated pleomorphic sarcoma [n = 10], osteosarcoma [n = 10], and other sarcomas [n = 7]) treated at the RP1bD, 4 (14.8%) had confirmed partial response (PR; 2 [7.4%] unconfirmed), 8 (29.6%) had stable disease, 11 (40.7%) had progressive disease; 2 (7.4%) were not evaluable. The median duration of response (confirmed responders) was 7.6 mo (95% CI: 5.6–9.2). Updated safety and efficacy data will be reported. Conclusions: ABBV-085 was well tolerated with durable PR observed in pts with advanced sarcomas. Clinical trial information: NCT02565758.

Phase 1/1b multicenter trial of TPST-1120, a peroxisome proliferator-activated receptor alpha (PPARα) antagonist as a single agent (SA) or in combination in patients with advanced solid tumors

TPS2665

Background: Tumor cells initially favor glucose metabolism via aerobic glycolysis. As tumors rapidly proliferate and metastasize, glucose stores are depleted and facilitated by a hypoxic tumor microenvironment (TME) and metabolic reprogramming shifts intracellular metabolism(IcM) towards fatty acid oxidation (FAO). Fatty acids support metabolism of suppressive immune cells in the TME in addition to tumor growth. PPARα is a ligand-activated nuclear transcription factor which regulates lipid metabolism and FAO. TPST-1120 is a first in class, oral selective PPARα antagonist that blocks transcription of PPARα target genes leading to an intracellular metabolism shift from FAO to glycolysis. Reduction of fatty acids in the TME leads to direct killing of tumor cells dependent on FAO, skews macrophages from immune suppressive M2 phenotype to an effector M1 phenotype and facilitates the cytotoxicity of immune effector cells. TPST-1120 also restores thrombospondin-1, a known natural inhibitor of angiogenesis, to homeostatic levels within the TME. TPST-1120 has an IC50 of 0.04 nM with > 35 fold selectivity over other PPAR isoforms. Preclinical studies in multiple tumor models show efficacy of TPST-1120 as a SA and in combination(combo) with an anti-PD1 monoclonal antibody (mAb) and chemotherapy. Methods: We have initiated a phase 1/1b multicenter, open label Dose Escalation (DEs) and Dose Expansion (DEx) trial to evaluate TPST-1120 as a SA and in combo with nivolumab, an anti-PD1 mAb; docetaxel, a chemotherapeutic agent and cetuximab, an anti-EGFR mAb. Objectives: 1) evaluate safety and tolerability of continuous dosing of TPST-1120 2) identify a recommended phase 2 dose (RP2D) and 3) evaluate efficacy. Eligibility: 1) patients with select advanced solid tumors who have failed 1 and up to 5 prior therapies. This phase 1/1b adaptive design has 4 DEs arms, 1 SA arm and 3 combination arms in which TPST-1120 is combined with nivolumab, docetaxel or cetuximab. The RP2D of TPST-1120 to proceed to DEx will be determined by safety and biomarkers during DEs. The DEx arms have 8 histology-specific cohorts, 4 SA arms and 4 combo arms and will follow a 2-stage expansion design. Biomarker analyses include gene expression profiling of PPARα-associated genes, tumor markers of immune modulation and serum lipid profiling. The total sample size is up to 338 pts. This trial is accruing at U.S sites. Clinical trial information: NCT03829436.

A phase I/Ib multicenter study to evaluate the humanized anti-CD73 antibody, CPI-006, as a single agent, in combination with CPI-444, and in combination with pembrolizumab in adult patients with advanced cancers

TPS2646

Background: CD73 expression is elevated in tumors and contributes to increasing levels of immunosuppressive adenosine in the tumor microenvironment. CD73 knockout mice exhibit reduced tumor growth and resistance to experimental metastasis. Inhibition of CD73 activity with an anti-CD73 antibody blocks adenosine production, shown to inhibit tumor growth in syngeneic models. CPI-006 is a humanized IgG1 FcγR binding-deficient anti-CD73 antibody now being investigated in this Phase 1/1b multicenter, open label trial as single agent (SA) or combination with CPI-444, an oral, small molecule, selective A2aR antagonist or in combination with pembrolizumab, an anti-PD1 indicated for the treatment of patients across a number of malignancies (NCT03454451). Methods: Up to 462 subjects will be enrolled at approximately 35 sites in the US, Canada and Australia. Eligible patients must have: non-small cell lung, renal cell carcinoma, urothelial bladder, cervical, colorectal, ovarian, pancreatic, prostate, head and neck, triple-negative breast, endometrial, select sarcomas and non-Hodgkin lymphoma malignancies relapsed, refractory or intolerant to 1 to 5 standard therapies; aged ≥ 18 yo; adequate organ function and measurable disease. The objectives of the study are 1) evaluate the safety and tolerability of SA CPI-006, in combination with CPI-444 and in combination with pembrolizumab, 2) evaluate the pharmacokinetics of each regimen and 3) identify potential biomarker signals predictive of response. Study design in table. Study Design. Clinical trial information: NCT03454451. [Table: see text]

A phase I, first-in-human, open label, dose-escalation and cohort expansion study of MGD019, a bispecific DART protein binding PD-1 and CTLA-4 in patients with unresectable or metastatic neoplasms

TPS2661

Background: Immune checkpoint molecules, including CTLA-4 and PD-1, attenuate the duration and strength of adaptive immune responses to limit immune-mediated tissue damage. Tumors may inhibit cellular immune activation by expressing ligands that bind checkpoint molecules and inhibit T-cell function in the tumor microenvironment. Blockade of these inhibitory pathways is the primary mechanism of action of several novel cancer immunotherapy agents. Combined blockade of PD-1 and CTLA-4 with two checkpoint inhibitors, ipilimumab and nivolumab, increases antitumor activity beyond either single agent alone in patients with metastatic melanoma or other malignancies. MGD019, a novel bispecific molecule that co-engages and coordinately inhibits both PD-1 and CTLA-4 signaling, was developed to potentially improve antitumor activity and/or safety relative to the monoclonal antibody combination. MGD019 is an Fc-bearing tetravalent DART molecule (bivalent for each antigen) that can independently block either checkpoint molecule, with preferential co-blockade in cells co-expressing both molecules demonstrated in vitro. It is hypothesized that MGD019 might be clinically active in either checkpoint naïve or checkpoint experienced patients after prior PD-1/PD-L1 inhibitors. Methods: This Phase 1 study will characterize safety, dose limiting toxicities, and maximum tolerated dose (MTD)/maximum administered dose (MAD) of MGD019. Dose Escalation will enroll patients with advanced solid tumors of any histology in sequential escalating doses in cohorts of 3 to 9 patients in a 3+3+3 design. Once the MTD/MAD is reached, a Cohort Expansion phase will characterize safety and initial antitumor activity per RECIST v1.1 and irRECIST in patients with specific tumor types anticipated to be sensitive to dual checkpoint blockade. Additional endpoints include pharmacokinetics; immunogenicity; impact of MGD019 on various measures of immune-regulatory effects in peripheral blood and biopsy specimens; and relationship between antitumor activity and gene profiles, tumor mutational burden, and PD-1, PD-L1, and CTLA-4 expression on tumor cells and immune cell infiltrates within biopsy specimens. Patients will be followed for survival approximately every 3 months for 2 years. Clinical trial information: NCT03761017.

Correlates of overall survival (OS) in metastatic uveal melanoma (mUM) and a randomized trial of cabozantinib (cabo) versus chemotherapy (chemo)

9506

Background: Survival is poor in mUM and treatment options are limited. MET kinase is over-expressed on UM and the MET inhibitor cabo showed activity in an early trial. Methods: A091201 was a 2:1 randomized phase II study testing progression-free survival (PFS) of cabo (60 mg daily) vs chemo (DTIC/TMZ). We studied baseline metastatic tumor samples (n = 19; 1 lung, 18 liver) by whole exome sequencing (WES) and RNAseq. We correlated data with OS and made comparisons for mUM vs. primary tumors from TCGA (n = 80). Results: 46 patients were accrued with 96% and 63% with liver metastases and elevated LDH, respectively. Toxicities were similar to prior reports of cabo and chemo. The trial stopped at interim analysis due to no difference in PFS (p = 0.964; HR = 0.99) or OS (p = 0.580; HR = 1.21). WES showed tumor mutational burden of 46±4 (mean±SEM) and did not separate OS at 1 year (p = 0.14, two-sided Wilcoxon rank sum test) in A091201. Recurrent known mutations included GNAQ/11, SF3B1, BAP1; novel mutations included GOLGA6L10, PKD1L3, and FAM228B. Gene expression signatures differed significantly between A091201 and TCGA cohorts including MET signaling (p = 7.87e-22), T cell-inflamed (p = 0.004), homologous recombination deficiency (p = 0.004), proliferation (p = 0.009) and hypoxia (p = 5.2e-10) (two-sided Student’s t-test). Tumor immune cell enrichment analysis revealed significant differences with lower M1:M2 macrophage (p = 1.2e-10) and higher Tregs (p = 6.0E-21) in mUM relative to TCGA (two-sided Wilcoxon rank sum test). Epithelial-mesenchymal transition gene expression signature was significantly associated with worse OS in A091201 (p = 0.02) with angiogenesis signature trending toward significance (p = 0.21) (log-rank test). OS separated by differentially expressed genes with OS ≤ 1 year associating with increased expression of the angiogenesis/immune-associated molecule neuropilin 1. Conclusions: These results provide insights between primary and mUM indicating potential novel therapeutic approaches. Support: U10CA180821, U10CA180882, T32GM007019, Exelixis. https://acknowledgments.alliancefound.org ; Clinical trial information: NCT01835145.

Comprehensive Clinical Trial Data Summation for BRAF-MEK Inhibition and Checkpoint Immunotherapy in Metastatic Melanoma

This review focuses on checkpoint and BRAF inhibitors, exploring outcomes based on clinical and disease characteristics to identify trends that might inform treatment decisions for the management of melanoma.

Background.

Immune checkpoint inhibitors, along with BRAF and MEK inhibitors, have dramatically changed the management of and outlook for patients with metastatic melanoma. Analyses of long‐term follow‐up data and subanalyses based on disease characteristics may inform clinical decision making.

Methods.

Reports of clinical trials in metastatic melanoma published between January 1, 2012, and August 30, 2018, were identified using PubMed (terms: melanoma AND [dabrafenib OR trametinib OR vemurafenib OR cobimetinib OR encorafenib OR ipilimumab OR nivolumab OR pembrolizumab]) and were systematically reviewed. Relevant congress proceedings were also assessed. Efficacy data from key phase III trials were analyzed and trends identified.

Results.

Substantial improvements in objective response rates, progression‐free survival, and overall survival were documented across 14 identified publications. Subgroup findings supported that patients with lower disease burden derive greater benefit than patients with more advanced disease, limiting the value of disease burden in the clinical decision‐making process. However, these agents consistently conferred benefits despite the presence of poor prognostic features. Several clinically relevant questions remain, including how best to sequence immune checkpoint inhibitors and combination targeted therapy.

Conclusion.

This research, coupled with ongoing investigations, including those on predictive biomarkers, suggests that the treatment decision‐making process is likely to become more nuanced.

Implications for Practice.

The management of melanoma has been rapidly advancing with new classes of agents, including immune checkpoint and BRAF inhibitors. With long‐term follow‐up, their impact on response rates and survival outcomes is well documented. Additional findings from subgroup analyses suggest that patients with lower disease burden derive greater benefit, yet both consistently confer benefit in patients with higher disease burden. Currently, there is a paucity of data to guide first‐line treatment selection between immunotherapy and BRAF‐targeted therapy in clinical practice or to estimate their impact when sequenced. Gaining these insights will facilitate a more nuanced management approach.

Phase III KEYNOTE-716 study: Adjuvant therapy with pembrolizumab versus placebo in resected high-risk stage II melanoma

TPS145

Background: Adjuvant pembrolizumab showed significantly longer recurrence-free survival compared with placebo in resected stage III melanoma in the KEYNOTE-054 study [1]. KEYNOTE-716 is a randomized, placebo-controlled, multicenter phase 3 study of adjuvant pembrolizumab in patients with surgically resected high-risk stage II melanoma. Methods: Patients must be ≥12 years of age and have newly diagnosed, completely resected stage IIB/IIC cutaneous melanoma, defined by the AJCC Cancer Staging Manual, 8th edition [2] (wide excision and negative sentinel lymph node biopsy, with no evidence of distant metastasis). Patients cannot have mucosal or uveal melanoma or have received prior treatment for melanoma, including radiation, beyond resection of primary disease within 12 weeks of the start of study therapy. The study has a 2-part design. In the double-blind phase (part 1), patients will be randomly assigned 1:1 to receive pembrolizumab 200 mg for patients ≥18 years or 2 mg/kg for patients 12-17 years (maximum dose, 200 mg) or placebo every 3 weeks for 17 cycles. Stratification: 1 stratum for pediatric patients (12-17 years); 3 strata for adult patients per T stage (T3b/T4a/T4b). Study treatment will begin within 12 weeks of complete resection. Tumor imaging will be performed every 24 weeks while treatment is ongoing, at the end of treatment, every 6 months for the first 3 years off treatment, and then yearly for up to 2 years or until recurrence (up to 5 years of total imaging). Adverse events will be graded per NCI Common Terminology Criteria for Adverse Events, version 4.0. In the unblinded phase (part 2), patients with confirmed recurrence may be rechallenged (patients received pembrolizumab in part 1) or crossed over to pembrolizumab (patients received placebo in part 1). Resected local or distant recurrence or unresectable disease will be treated for an additional 17 or 35 cycles, respectively. Tumor imaging in part 2 will occur every 12 weeks while treatment is ongoing. The primary end point is recurrence-free survival; secondary end points are distant metastasis-free survival, overall survival, and safety. Approximately 954 patients will be enrolled. Clinical trial information: NCT03553836.

Real-world time to next treatment (TTNT) for first-line (1L) targeted and immuno-oncology therapies for BRAF-mutated metastatic melanoma (MM) by lactate dehydrogenase (LDH) level

141

Background: Dabrafenib plus trametinib (D+T), ipilimumab plus nivolumab (I+N), and both nivolumab and pembrolizumab (“PD-1 mono”) are approved for the 1L treatment of MM. This study reports real world 1L TTNT for patients receiving these therapies by LDH status. Methods: This was a retrospective, observational study. MM patients initiating 1L treatment with D+T, I+N, or PD-1 monotherapy from Jan-2014 through Jun-2017 were identified from community oncology practices in the U.S. Patients treating oncologist abstracted patient date into case report forms. LDH at initiation of treatment was classified by the provider as normal or abnormal ( > 1x and < 2x ULN or ≥ 2x ULN) according to the reference laboratory. TTNT was calculated from 1L initiation to initiation of second-line (2L). Cox proportional hazard models estimated the risk of initiating 2L (proxy for progression) between groups adjusted for age, gender, brain/liver metastases (mets), number of mets and ECOG-PS. Results: Data for 332 patients were submitted by 53 providers including 51.6% who initiated 2L. Abnormal LDH: D+T = 60.3%, ipi/nivo = 53.0%, PD-1 mono = 35.4%. No differences in the frequency of patients with stage IV M1c, brain mets, ECOG, or discontinuation due to toxicity (8.4% of all patients) were noted between cohorts. TTNT was significantly longer in both normal and abnormal LDH cohorts for D+T (14.1 and 11.6 mo.) vs. ipi/nivo (10.1 and 10.2 mo.) but not PD-1 mono (13.3 and 10.6). Adjusted for confounding variables in the abnormal LDH cohort the hazard ratio (HR) for risk of 2L initiation was significantly higher (2.08, p < 0.01) for ipi/nivo vs. D+T but not significant different among normal LDH patients (HR = 1.89, p = 0.054). No significant difference in the risk of 2L initiation between D+T and ipi/nivo were noted in either the normal or abnormal cohorts. Conclusions: For normal and abnormal LDH cohorts 1L TTNT was longer for patients receiving D+T vs. ipi/nivo (but not vs. PD-1 mono). Using the multivariate model we observed the risk of 2L initiation, a proxy for progression, was higher for ipi/nivo treated vs. D+T adjusted for clinical factors for abnormal LDH patients.

Long-term clinical outcomes and transcriptional analysis following partial and complete tumor SBRT plus pembrolizumab

34

Background: Preclinical models support a combinatorial role of high-dose irradiation with immunotherapy. Multi-site stereotactic body radiotherapy (SBRT) with pembrolizumab (P) has been demonstrated as safe in advanced solid tumors. Here, we report extended follow-up of treated metastasis control (TMC), progression-free survival (PFS), overall survival (OS) and describe transcriptional changes associated with TMC, PFS and OS. Methods: Patients (pts) with AST received 3-5 SBRT doses (30-50 Gy total dose) to 2-4 metastases based on anatomic location. Pembrolizumab (200 mg IV Q3W) began one week following the final SBRT. Mets >65cc received partial-tumor SBRT. Response was measured by RECIST principles. TMC, PFS, and OS were estimated by Kaplan-Meier method. Pre- and post-SBRT biopsies from 24 pts were assayed via RNA microarray. Results: 68 pts (140 mets) were enrolled. 18 pts (21 mets) received partial tumor SBRT. Median volume of partially irradiated tumors was 121cc vs 7cc of fully irradiated (p=0.001). Median follow-up was 8.4 months (mo; range 1.1-24.2). 1-year TMC was 89.6%. At 12 mo TMC of partial versus full tumor irradiation was not significantly different (p=0.09). On multiple Cox regression, metastasis size, histology, volume of irradiated tumor and PD-L1 status were not predictive of TMC, PFS or OS. However, irradiated metastasis response predicted OS (HR = 0.37; 95% CI, 0.19-0.71; p = 0.003). Pts with irradiated met PR or CR had 17.8 mo median OS vs 9.1 and 3.4 in pts with mixed response or PD, respectively (p=0.005). Unsupervised transcriptional analysis of tumor biopsies demonstrated that the magnitude of DNA repair and innate/adaptive immune pathways induced in irradiated mets following SBRT was significantly associated with irradiated met response (p=0.009) and OS (p=0.007) to SBRT+P. Conclusions: Partial tumor SBRT+P approximates full tumor SBRT+P despite major differences in tumor volume. Transcriptional changes and clinical response of irradiated mets to SBRT+P are highly predictive of OS. Further research is needed to optimize immuno-radiotherapy. Clinical trial information: NCT02608385.

BMS-986205, an indoleamine 2, 3-dioxygenase 1 inhibitor (IDO1i), in combination with nivolumab (nivo): Updated safety across all tumor cohorts and efficacy in advanced bladder cancer (advBC)

358

Background: Nivo (anti–PD-1) has shown durable responses and manageable safety (ORR, 19.6%; grade 3‒4 treatment-related AEs [TRAEs], 18%) in advBC (Sharma et al. Lancet Oncol 2017), but prolonging survival in more pts requires additional approaches to overcome tumor evasion mechanisms. IDO1 allows tumor escape through kynurenine (KYN) production, which stimulates regulatory T cells and suppresses effector T-cell proliferation. Anti─PD-1 can upregulate IDO1, supporting the rationale for combining nivo with an IDO1i. BMS-986205 is a selective, potent, once-daily (QD) oral IDO1i that works early in the IDO1 pathway to reduce KYN production. BMS-986205 + nivo showed favorable safety and efficacy in heavily pretreated pts with select solid tumors (Luke et al. SITC 2017; NCT02658890). Updated safety across all tumor cohorts and efficacy in the immuno-oncology (I-O)–naive advBC cohort are reported. Methods: Dose-escalation methods in this phase 1/2a, open-label study were previously described; during expansion, pts received BMS-986205 100 or 200 mg QD + nivo 240 mg IV Q2W or 480 mg IV Q4W. Objectives included safety and ORR by RECIST v1.1 (includes unconfirmed responses). Results: As of Mar 2018, 516 pts received BMS-986205 + nivo; 45% had ≥2 prior regimens. TRAEs occurred in 57% of pts (grade 3‒4, 12%), the most common being fatigue (15%) and nausea (12%); 19 pts (4%) discontinued due to TRAEs, and 3 pts ( < 1%) died due to a TRAE (myocarditis, Stevens-Johnson syndrome, and hepatic failure). In all treated pts and within the advBC cohort (n = 30), the frequency and severity of TRAEs and rate of discontinuation due to TRAEs was lower with the 100- vs 200-mg BMS-986205 dose. Among the 27 pts with I-O–naive advBC, with a median duration of follow-up of 24 wk, ORR was 37% (3 CRs, 7 PRs), and the DCR was 56%; ORR in pts with tumor PD-L1 ≥1% (Dako PD-L1 IHC 28-8 pharmDx assay; n = 14) vs < 1% (n = 10) was 50% vs 30%. Conclusions: BMS-986205 + nivo was well tolerated in heavily pretreated pts, and tolerability was improved with the 100-mg BMS-986205 dose. Preliminary evidence of efficacy was observed in advBC, supporting further evaluation of BMS-986205 + nivo. Clinical trial information: NCT02658890.

Reimagining IDO Pathway Inhibition in Cancer Immunotherapy via Downstream Focus on the Tryptophan-Kynurenine-Aryl Hydrocarbon Axis

Significant progress has been made in cancer immunotherapy with checkpoint inhibitors targeting programmed cell death protein 1 (PD-1)-programmed death-ligand 1 signaling pathways. Tumors from patients showing sustained treatment response predominately demonstrate a T cell-inflamed tumor microenvironment prior to, or early on, treatment. Not all tumors with this phenotype respond, however, and one mediator of immunosuppression in T cell-inflamed tumors is the tryptophan-kynurenine-aryl hydrocarbon receptor (Trp-Kyn-AhR) pathway. Multiple mechanisms of immunosuppression may be mediated by this pathway including depletion of tryptophan, direct immunosuppression of Kyn, and activity of Kyn-bound AhR. Indoleamine 2,3-dioxygenase 1 (IDO1), a principle enzyme in Trp catabolism, is the target of small-molecule inhibitors in clinical development in combination with PD-1 checkpoint inhibitors. Despite promising results in early-phase clinical trials in a range of tumor types, a phase III study of the IDO1-selective inhibitor epacadostat in combination with pembrolizumab showed no difference between the epacadostat-treated group versus placebo in patients with metastatic melanoma. This has led to a diminution of interest in IDO1 inhibitors; however, other approaches to inhibit this pathway continue to be considered. Novel Trp-Kyn-AhR pathway inhibitors, such as Kyn-degrading enzymes, direct AhR antagonists, and tryptophan mimetics are advancing in early-stage or preclinical development. Despite uncertainty surrounding IDO1 inhibition, ample preclinical evidence supports continued development of Trp-Kyn-AhR pathway inhibitors to augment immune-checkpoint and other cancer therapies.

Targeted agents or immuno-oncology therapies as first-line therapy for BRAF-mutated metastatic melanoma: a real-world study

Aim: Targeted therapy (TT) and immuno-oncology (IO) drugs are approved for patients with BRAF mutant metastatic melanoma (MM). We compared real-world outcomes for first-line (1L) TT versus 1L IO to evaluate optimal sequencing. Materials & methods: Physicians-identified BRAF mutant MM patients initiating 1L TT or IO therapies and extracted treatment, disease and clinical outcomes including disease response which were compared between TT and IO and individual regimens. Results: 440 MM patients (TT = 283, IO = 157) were identified. A higher proportion of TT patients had liver metastases (46.3 vs 35.0%) and abnormal lactate dehydrogenase (61.1 vs 42.7%). IO-treated had a RECIST-determined response rate of 45.9 versus 60.1% for TT and time on treatment of 7.2 versus 11.4 months, respectively. There was no survival difference between cohorts. Conclusion: Despite higher risk patients, 1L TT resulted in higher response rate and longer treatment duration suggesting a preferred 1L sequence.

Response to Anti-PD-1 in Uveal Melanoma Without High-Volume Liver Metastasis

Background: Uveal melanoma (UM) is an uncommon melanoma subtype with poor prognosis. Agents that have transformed the management of cutaneous melanoma have made minimal inroads in UM. Methods: We conducted a single-arm phase II study of pembrolizumab in patients with metastatic UM and performed bioinformatics analyses of publicly available datasets to characterize the activity of anti-PD-1 in this setting and to understand the mutational and immunologic profile of this disease. Results: A total of 5 patients received pembrolizumab in this study. Median overall survival was not reached, and median progression-free survival was 11.0 months. One patient experienced a complete response after one dose and 2 others experienced prolonged stable disease (20% response rate, 60% clinical benefit rate); 2 additional patients had rapidly progressing disease. Notably, the patients who benefited had either no liver metastases or small-volume disease, whereas patients with rapidly progressing disease had bulky liver involvement. We performed a bioinformatics analysis of The Cancer Genome Atlas for UM and confirmed a low mutation burden and low rates of T-cell inflammation. Note that the lack of T-cell inflammation strongly correlated with MYC pathway overexpression. Conclusions: Anti-PD-1-based therapy may cause clinical benefit in metastatic UM, seemingly more often in patients without bulky liver metastases. Lack of mutation burden and T-cell infiltration and MYC overexpression may be factors limiting therapeutic responses.ClinicalTrials.gov identifier: NCT02359851.

A phase 2 study of glembatumumab vedotin, an antibody-drug conjugate targeting glycoprotein NMB, in patients with advanced melanoma

BACKGROUND

Glembatumumab vedotin is an antibody-drug conjugate that produced preliminary clinical activity against advanced melanoma in a phase 1 dose-escalation trial. The objective of the current study was to investigate further the antitumor activity of glembatumumab vedotin at the recommended phase 2 dose in heavily pretreated patients with melanoma.

METHODS

This single-arm, phase 2 study enrolled patients with stage IV melanoma who were refractory to checkpoint inhibition and to B-raf proto-oncogene, serine/threonine kinase (BRAF)/mitogen-activated protein kinase kinase (MEK) inhibition (in the presence of a BRAF valine mutation at codon 600). Patients received 1.9 mg/kg glembatumumab vedotin intravenously every 3 weeks until they developed disease progression or intolerance. The primary endpoint was objective response rate (ORR), which was determined according to Response Evaluation Criteria in Solid Tumors, version 1.1. Secondary endpoints included progression-free survival (PFS), duration of response, overall survival (OS), safety, and clinical efficacy versus tumor glycoprotein NMB (gpNMB) expression. Tumor expression of gpNMB was assessed using immunohistochemistry.

RESULTS

In total, 62 patients received treatment. The ORR was 11% and the median response duration was 6.0 months (95% confidence interval [CI], 4.1 months to not reached). The median PFS was 4.4 months (95% CI, 2.6-5.5 months), and the median OS was 9.0 months (95% CI, 6.1-11.7 months). For patients who developed rash during the first cycle versus those who did not, the ORR was 21% versus 7%, respectively, and there was an overall improvement in PFS (hazard ratio, 0.43; P = .013) and OS (hazard ratio, 0.43; P = .017). The most frequent adverse events were alopecia, neuropathy, rash, fatigue, and neutropenia. With one exception, all evaluable tumors were positive for gpNMB, and 46 of 59 tumors (76%) had 100% gpNMB-positive epithelial cells.

CONCLUSIONS

Glembatumumab vedotin had modest activity and an acceptable safety profile in patients with advanced melanoma who were refractory to checkpoint inhibitors and MEK/BRAF inhibition. Treatment-related rash may be associated with response.

WNT/β-catenin Pathway Activation Correlates with Immune Exclusion across Human Cancers

PURPOSE

The T-cell-inflamed phenotype correlates with efficacy of immune-checkpoint blockade, whereas non-T-cell-inflamed tumors infrequently benefit. Tumor-intrinsic WNT/β-catenin signaling mediates immune exclusion in melanoma, but association with the non-T-cell-inflamed tumor microenvironment in other tumor types is not well understood.

EXPERIMENTAL DESIGN

Using The Cancer Genome Atlas (TCGA), a T-cell-inflamed gene expression signature segregated samples within tumor types. Activation of WNT/β-catenin signaling was inferred using three approaches: somatic mutations or somatic copy number alterations (SCNA) in β-catenin signaling elements including CTNNB1, APC, APC2, AXIN1, and AXIN2; pathway prediction from RNA-sequencing gene expression; and inverse correlation of β-catenin protein levels with the T-cell-inflamed gene expression signature.

RESULTS

Across TCGA, 3,137/9,244 (33.9%) tumors were non-T-cell-inflamed, whereas 3,161/9,244 (34.2%) were T-cell-inflamed. Non-T-cell-inflamed tumors demonstrated significantly lower expression of T-cell inflammation genes relative to matched normal tissue, arguing for loss of a natural immune phenotype. Mutations of β-catenin signaling molecules in non-T-cell-inflamed tumors were enriched three-fold relative to T-cell-inflamed tumors. Across 31 tumors, 28 (90%) demonstrated activated β-catenin signaling in the non-T-cell-inflamed subset by at least one method. This included target molecule expression from somatic mutations and/or SCNAs of β-catenin signaling elements (19 tumors, 61%), pathway analysis (14 tumors, 45%), and increased β-catenin protein levels (20 tumors, 65%).

CONCLUSIONS

Activation of tumor-intrinsic WNT/β-catenin signaling is enriched in non-T-cell-inflamed tumors. These data provide a strong rationale for development of pharmacologic inhibitors of this pathway with the aim of restoring immune cell infiltration and augmenting immunotherapy.See related commentary by Dangaj et al., p. 2943.

Complete response of metastatic melanoma in a patient with Crohn's disease simultaneously receiving anti-α4β7 and anti-PD1 antibodies

Background

Immune checkpoint inhibitors (ICPIs) are increasingly being used in the treatment of a variety of malignancies. The original studies that demonstrated the efficacy of ICPIs excluded patients actively being treated for autoimmune conditions, and there is only limited evidence that these treatments are safe and effective in this population of patients.

Case presentation

We present a case of a man with Crohn’s disease actively requiring immunosuppressive therapy who subsequently received pembrolizumab for metastatic melanoma. He had no further progression of metastatic disease and had resolution of his pulmonary nodule while he experienced no Crohn’s disease flares or immune related adverse events. We surveyed the existing literature for studies examining the use of ICPIs in patients with autoimmune disorders and reviewed the unique mechanism of action of the α4β7 inhibitor, vedolizumab.

Conclusion

Patients with autoimmune conditions should be considered candidates for immune checkpoint inhibition even in the setting of active immunosuppressive therapy. The mechanism of action of immunosuppressive therapy should be considered with the most targeted form of treatment being used when possible. Further prospective studies investigating immunotherapy in patients with autoimmune conditions are warranted.

Epacadostat Plus Pembrolizumab in Patients With Advanced Solid Tumors: Phase I Results From a Multicenter, Open-Label Phase I/II Trial (ECHO-202/KEYNOTE-037)

PURPOSE

Tumors may evade immunosurveillance through upregulation of the indoleamine 2,3-dioxygenase 1 (IDO1) enzyme. Epacadostat is a potent and highly selective IDO1 enzyme inhibitor. The open-label phase I/II ECHO-202/KEYNOTE-037 trial evaluated epacadostat plus pembrolizumab, a programmed death protein 1 inhibitor, in patients with advanced solid tumors. Phase I results on maximum tolerated dose, safety, tolerability, preliminary antitumor activity, and pharmacokinetics are reported.

PATIENTS AND METHODS

Patients received escalating doses of oral epacadostat (25, 50, 100, or 300 mg) twice per day plus intravenous pembrolizumab 2 mg/kg or 200 mg every 3 weeks. During the safety expansion, patients received epacadostat (50, 100, or 300 mg) twice per day plus pembrolizumab 200 mg every 3 weeks.

RESULTS

Sixty-two patients were enrolled and received one or more doses of study treatment. The maximum tolerated dose of epacadostat in combination with pembrolizumab was not reached. Fifty-two patients (84%) experienced treatment-related adverse events (TRAEs), with fatigue (36%), rash (36%), arthralgia (24%), pruritus (23%), and nausea (21%) occurring in ≥ 20%. Grade 3/4 TRAEs were reported in 24% of patients. Seven patients (11%) discontinued study treatment because of TRAEs. No TRAEs led to death. Epacadostat 100 mg twice per day plus pembrolizumab 200 mg every 3 weeks was recommended for phase II evaluation. Objective responses (per Response Evaluation Criteria in Solid Tumors [RECIST] version 1.1) occurred in 12 (55%) of 22 patients with melanoma and in patients with non-small-cell lung cancer, renal cell carcinoma, endometrial adenocarcinoma, urothelial carcinoma, and squamous cell carcinoma of the head and neck. The pharmacokinetics of epacadostat and pembrolizumab and antidrug antibody rate were comparable to historical controls for monotherapies.

CONCLUSION

Epacadostat in combination with pembrolizumab generally was well tolerated and had encouraging antitumor activity in multiple advanced solid tumors.

T Cell-Inflamed versus Non-T Cell-Inflamed Tumors: A Conceptual Framework for Cancer Immunotherapy Drug Development and Combination Therapy Selection

Immunotherapies such as checkpoint-blocking antibodies and adoptive cell transfer are emerging as treatments for a growing number of cancers. Despite clinical activity of immunotherapies across a range of cancer types, the majority of patients fail to respond to these treatments and resistance mechanisms remain incompletely defined. Responses to immunotherapy preferentially occur in tumors with a preexisting antitumor T-cell response that can most robustly be measured via expression of dendritic cell and CD8+ T cell-associated genes. The tumor subset with high expression of this signature has been described as the T cell-"inflamed" phenotype. Segregating tumors by expression of the inflamed signature may help predict immunotherapy responsiveness. Understanding mechanisms of resistance in both the T cell-inflamed and noninflamed subsets of tumors will be critical in overcoming treatment failure and expanding the proportion of patients responding to current immunotherapies. To maximize the impact of immunotherapy drug development, pretreatment stratification of targets associated with either the T cell-inflamed or noninflamed tumor microenvironment should be employed. Similarly, biomarkers predictive of responsiveness to specific immunomodulatory therapies should guide therapy selection in a growing landscape of treatment options. Combination strategies may ultimately require converting non-T cell-inflamed tumors into T cell-inflamed tumors as a means to sensitize tumors to therapies dependent on T-cell killing. Cancer Immunol Res; 6(9); 990-1000. ©2018 AACR.

An Empirical Approach Leveraging Tumorgrafts to Dissect the Tumor Microenvironment in Renal Cell Carcinoma Identifies Missing Link to Prognostic Inflammatory Factors

By leveraging tumorgraft (patient-derived xenograft) RNA-sequencing data, we developed an empirical approach, DisHet, to dissect the tumor microenvironment (eTME). We found that 65% of previously defined immune signature genes are not abundantly expressed in renal cell carcinoma (RCC) and identified 610 novel immune/stromal transcripts. Using eTME, genomics, pathology, and medical record data involving >1,000 patients, we established an inflamed pan-RCC subtype (IS) enriched for regulatory T cells, natural killer cells, TH1 cells, neutrophils, macrophages, B cells, and CD8+ T cells. IS is enriched for aggressive RCCs, including BAP1-deficient clear-cell and type 2 papillary tumors. The IS subtype correlated with systemic manifestations of inflammation such as thrombocytosis and anemia, which are enigmatic predictors of poor prognosis. Furthermore, IS was a strong predictor of poor survival. Our analyses suggest that tumor cells drive the stromal immune response. These data provide a missing link between tumor cells, the TME, and systemic factors.Significance: We undertook a novel empirical approach to dissect the renal cell carcinoma TME by leveraging tumorgrafts. The dissection and downstream analyses uncovered missing links between tumor cells, the TME, systemic manifestations of inflammation, and poor prognosis. Cancer Discov; 8(9); 1142-55. ©2018 AACR.This article is highlighted in the In This Issue feature, p. 1047.