Real-world patient-reported and clinical outcomes of BNT162b2 mRNA COVID-19 vaccine in patients with cancer

6510

Background: Most COVID-19 (C19) vaccine trials excluded patients with active cancer. Here, we report our real-world patient-reported and clinical outcomes of BNT162b2 mRNA C19 vaccine in patients with cancer. Methods: Our institutional Data-Driven Determinants for COVID-19 Oncology Discovery Effort (D3CODE) follows a longitudinal observational cohort of pts w cancer getting C19 vaccine. Pts complete a validated PRO tool, MD Anderson Symptom Inventory (MDASI, 13 core, 6 interference plus 17 items of symptoms from prior vaccine trials) pre-dose 1, then daily x 6d, then weekly, then on day of dose 2, then daily x 6d, then weekly x 3w. Demographics, cancer variables, prior immune checkpoint inhibitors (ICI), C19 status pre- & post-vaccine are aggregated via Syntropy platform: Palantir Foundry. Primary outcome is incidence of PRO symptoms bw dose 1 & 2 across AYA 15-39y, mid-age 40-64y & senior 65y+ cohorts. Secondary outcomes include PRO symptom incidence post-dose 2, post-vaccine change in cancer symptoms, post-vaccine symptom severity based on prior ICI, and confirmed C19 > 7 days post-dose 2. First planned 8-wk interim analysis is reported here. Results: 6388 pts w cancer (4973 w mets) received a BNT162b2 vaccine dose (4811 both doses, 1577 received one & await dose 2). Overall, median age 64y (range 16-95y); 382 AYAs, 2927 mid-age, 3079 seniors (65-70y n = 1158, 70-79y n = 1521, 80-89y n = 378, 90y+ n = 22). 4099 (64%) are White, 823 (13%) AA, 791 (12%) Hispanic, 441 (7%) Asians. Primary cancers: breast (1397), GU (821), heme (775), thoracic/HN (745), and CRC (385). Prior to dose 1, 1862 had no prior systemic tx while 4526 pts did including 3243 who had only non-IO tx (chemo, targeted tx), 1,283 had immunotherapy including 857 who had ICIs prior to dose 1. Patient-reported symptoms after C19 Vaccine: Of 6388 pts, 4714 (74% response rate, median age 67y, range 16-95y) completed 16485 PRO surveys. After 2 doses, seniors reported lower mean scores vs mid-age or AYAs on 22 of 36 symptoms including injection site pain, palpitations, itch, rash, malaise, fevers/chills, arthralgia, myalgia, headache, pain, fatigue, nausea, disturbed sleep, distress (p < 0.05). Pts w prior ICIs had higher severity of itch, rash (p < 0.05) from baseline after both dose 1 & 2 vs pts without systemic tx. Post dose 1, pts with prior ICI had higher increase in fatigue, malaise, itch, rash, myalgia, anorexia from their baseline vs pts without systemic tx (p < 0.05). C19 Outcomes: Of 6388 pts, 616 had a C19 test at any time post-dose 1: 23 (0.36%) tested positive of whom 20 (0.3%) were between dose 1 & 2; two (0.031%) were within 7 days post-dose 2, and one patient (0.016%) tested positive 16 days after dose 2, requiring admission. Conclusions: This real-world observational cohort demonstrates post-vaccine symptom burden and outcomes in patients with cancer. Second interim analysis is planned at 16 weeks.

Pyrexia-related outcomes upon application of an adapted pyrexia management algorithm in patients (pts) with BRAF V600: Mutant unresectable or metastatic melanoma treated with dabrafenib plus trametinib (DabTram) in the COMBI-i trial

9560

Background: First-line DabTram has shown long-term efficacy in pts with BRAF V600–mutant unresectable or metastatic melanoma in the Phase III COMBI-d and COMBI-v trials. Data from the Phase III COMBI-i trial comparing spartalizumab plus DabTram vs placebo plus DabTram (pbo-DabTram) demonstrated efficacy in the pbo-DabTram arm, consistent with historical data. Pyrexia (single preferred term [PT]) is the most common adverse event (AE) reported with DabTram (pooled COMBI-d [data cutoff: Jan 12, 2015] and COMBI-v [data cutoff: Apr 17, 2014]: any grade, 54.2%; grade ≥ 3, 5.4%; serious pyrexia AEs leading to hospitalization, 11.8%). A new pyrexia management algorithm was implemented in the COMBI-i trial to improve pyrexia-related outcomes. We report pyrexia-related outcomes in pts treated with pbo-DabTram in the control arm of COMBI-i part 3. Methods: COMBI-i (NCT02967692) part 3 is a double-blind, Phase III trial in which pts with previously untreated BRAF V600–mutant unresectable or metastatic melanoma were randomized 1:1 to receive spartalizumab (400 mg intravenously every 4 weeks) plus Dab (150 mg orally twice daily) and Tram (2 mg orally once daily) vs pbo-DabTram. In the adapted pyrexia management algorithm, both Dab and Tram are interrupted promptly at the first symptom of pyrexia or its associated prodrome (ie, chills, rigors, night sweats, or influenza-like symptoms). Treatment at the same dose level is restarted upon the improvement of symptoms if pts are symptom free for ≥ 24 hours. Pyrexia incidence rates presented are for the single PT of pyrexia. Results: At data cutoff (July 1, 2020), median follow-up was 27.2 mo for all pts enrolled in COMBI-i part 3 (N = 532). In the DabTram control arm, 52.7% (139/264) and 3.0% (8/264) of pts had any-grade and grade ≥ 3 pyrexia, respectively. Serious pyrexia AEs were reported in 6.1% (16/264), which led to hospitalization in 5.3% (14/264). Pyrexia led to dose interruption of both Dab and Tram in 39.0% (103/264), with 1.5% (4/264) permanently discontinuing both agents. Median relative dose intensity was 97.8% for Dab and 97.7% for Tram. Conclusions: Pyrexia-related outcomes, including grade ≥ 3 pyrexia (3.0% vs 5.4%) and serious pyrexia AEs leading to hospitalization (5.3% vs 11.8%), were improved in pts treated with DabTram in COMBI-i part 3 compared with historical data from COMBI-d/v. The adapted algorithm offers a simplified approach for managing pyrexia, thereby reducing the incidence of severe pyrexia while maintaining consistent efficacy with DabTram. Clinical trial information: NCT02967692.

Outcomes of BRAF mutant metastatic melanoma (MM) patients (pts) after cessation of targeted therapy (TT) with BRAF or BRAF/MEK inhibitor(i)

9564

Background: Since their introduction into the clinic a decade ago, BRAF and BRAF/MEKi have dramatically changed the outcomes of pts with BRAF mutant MM. While typically, these agents are administered until progression (PD), other reasons for stopping TT include unacceptable toxicity, complete response to treatment, or pt/physician decision or preference. The outcomes for MM pts that stop TT for reasons other than PD are largely unknown. Here we report the clinical features and outcomes of the largest cohort of MM pts who stopped TT for reasons other than PD to date. Methods: Under an institutionally approved database, we identified MM pts treated at the MD Anderson Cancer Center with BRAF±MEK inhibitors, and their records were reviewed to identify pts that stopped TT for reasons other than PD. Pts demographics, treatment information and clinical outcomes were recorded. Overall survival (OS) time was computed from three start dates (initial diagnosis, initial unresectable stage III melanoma, 1st dose of TT) to last known vital sign. Pts alive at the last follow-up date were censored. Time to recurrence was computed from date of 1st dose of TT to recurrence. Pts who did not experience disease recurrence were censored The Kaplan-Meier method was used to estimate OS and time to recurrence. Results: A total of 58 pts were identified, 32 (55%) were male. Most pts had a BRAF V600E (n = 49) or V600K (n = 6) mutation. At TT initiation median age was 59.5 years (range 29- 95), LDH was within normal range in 46 (85%), median number of prior systemic therapies was 1 (range 0-5), with 50% of pts receiving prior systemic therapy. Most (n = 33; 57%) pts were treated with single agent BRAFi (12 with dabrafenib, 11 vemurafenib). Among pts treated with combination TT (n = 25), most received dabrafenib with trametinib (n = 21; 84%). Median TT treatment duration was 9.5 months (range 0.03-80.5 months). Reasons for TT discontinuation were unacceptable toxicity (n = 29; 50%) and pt or physician decision/preference in responding patients (n = 23; 40%). At time of TT discontinuation, 48% of pts had achieved a complete response (CR), 28% a partial response (PR), and 22% stable disease (SD), 1 patient had unknown disease status. With standard follow-up, after stopping TT, 40 pts (69%) have recurred or experienced PD, with a median time to recurrence of 14.9 months (95% CI:7.8-26.3 months). At PD, 32 (76%) of pts had new metastatic sites. After PD 26 pts (63%) pts received BRAF/MEKi, 11 (44%) achieved a CR and 6 (24%) a PR, and 5 (20%) for a response rate of 88%; while 3 (12%) pt had PD as best response and 1 was unknown. For the full cohort, the median OS from time of 1st dose of TT was 6.4 years. Conclusions: Among MM pts who stopped TT for reasons other than PD, the majority of pts recurred, but most responded to re-introduction of TT. This information can help to inform discussion with pts regarding cessation of, or re-challenge with, TT.

Relatlimab (RELA) plus nivolumab (NIVO) versus NIVO in first-line advanced melanoma: Primary phase III results from RELATIVITY-047 (CA224-047)

9503

Background: Immune checkpoint inhibitor therapy has revolutionized the treatment of patients with advanced melanoma. However, novel combinations are needed to optimize the benefit-risk profile. Lymphocyte-activation gene 3 (LAG-3) regulates an immune checkpoint pathway, which inhibits T-cell activity, and is upregulated in many tumor types including melanoma. Relatlimab (RELA), a human IgG4 LAG-3-blocking antibody, restores effector function of exhausted T cells. RELA in combination with nivolumab (NIVO; anti-programmed death [PD]-1) modulates potentially synergistic immune checkpoint pathways and can enhance antitumor immune responses. RELATIVITY-047 is a global, randomized, double-blind, phase II/III study evaluating a novel immune checkpoint inhibitor combination of RELA+NIVO as a fixed-dose combination (FDC) treatment in first-line advanced melanoma. Methods: Patients with previously untreated advanced melanoma were randomized 1:1 to receive RELA 160 mg + NIVO 480 mg FDC intravenously (IV) every 4 weeks (Q4W) or NIVO monotherapy 480 mg IV Q4W, stratified by LAG-3 expression, programmed death ligand 1 expression, BRAF mutation status, and AJCC (v8) M stage. The primary endpoint was progression-free survival (PFS) per RECIST v1.1 as assessed by blinded independent central review. Secondary endpoints were overall survival and objective response rate. PFS in prespecified subgroups and safety were additional objectives. Results: 714 patients were randomized to RELA+NIVO FDC (n = 355) or NIVO (n = 359). Patient characteristics were well balanced between treatment groups. Median follow-up was 13.2 months. Median PFS in the RELA+NIVO FDC group (10.1 months [95% CI, 6.4–15.7]) was significantly longer than in the NIVO group (4.6 months [95% CI, 3.4–5.6]; hazard ratio, 0.75 [95% CI, 0.6–0.9]; P = 0.0055). PFS rates at 12 months were 47.7% (95% CI, 41.8–53.2) and 36.0% (95% CI, 30.5–41.6) for RELA+NIVO FDC and NIVO, respectively. PFS favored RELA+NIVO FDC across key prespecified subgroups. The incidence of grade 3/4 treatment-related adverse events (TRAEs) was higher in the RELA+NIVO FDC group (18.9%) versus NIVO (9.7%). There were 3 treatment-related deaths with RELA+NIVO FDC and 2 with NIVO. TRAEs (any grade) led to treatment discontinuation in 14.6% and 6.7% of patients in the RELA+NIVO FDC and NIVO groups, respectively. Conclusions: First-line treatment with RELA+NIVO FDC demonstrated a statistically significant PFS benefit compared to NIVO monotherapy in patients with advanced melanoma. RELA+NIVO FDC was well tolerated with a manageable safety profile and without unexpected safety signals. This is the first phase III study of a novel FDC to demonstrate a clinically meaningful benefit by dual inhibition of the LAG-3 and PD-1 pathways. Clinical trial information: NCT03470922.

Predictors of overall survival (OS) in patients (pts) with melanoma brain metastasis (MBM) in the modern era

9540

Background: The management and OS of pts with metastatic melanoma have improved due to new systemic therapies. However, relatively little is known about the use of these treatments (tx) and their association with OS in pts with MBMs. We reviewed a large cohort of MBM pts to assess how pt demographics, disease characteristics, and MBM tx impact OS in the current era. Methods: Under an institutional review board-approved protocol, retrospective data were curated and analyzed from pts diagnosed with, and received tx for, MBM from 2014 to 2018 at the MD Anderson Cancer Center (MDA). Pts diagnosed with uveal or mucosal melanoma or other cancers were excluded. Pt demographics; timing and features of initial melanoma dx; timing and features of initial MBM dx; prior, initial and subsequent tx; and OS were collected. OS was determined from MBM dx to last clinical follow-up (FU). Pts alive at last FU were censored. The Kaplan-Meier method and log-rank test were used to estimate OS and to assess univariate group differences, respectively. Multivariable (MV) associations of OS with variables of interest were investigated with Cox proportional hazards models. Initial treatment of MBM was assessed as a time-varying covariate. All statistical tests used a significance level of 5%. Results: A total of 401 MBM pts were identified. The median age at MBM dx was 61; 67% were male and 46% had a BRAF V600 mutation. At MBM diagnosis dx, most (70%) pts were asymptomatic; 70% had concurrent uncontrolled extracranial disease; 36% had elevated serum LDH. Prior tx included immunotherapy (IMT) for 39% and targeted therapy (TTX) for 17%. The median number of MBMs was 2; 31% had > 3 MBMs. Median largest MBM diameter was 1.0 cm, 9% had MBM > 3.0 cm, and 5% had concurrent leptomeningeal disease (LMD). Tx received after MBM dx included stereotactic radiosurgery (SRS; 53% as initial tx for MBM, 67% at any time after MBM dx), whole brain radiation therapy (WBRT; 16%, 35%), craniotomy (12%, 19%), IMT (37%, 74%), and/or TTX (22%, 40%). 31% received steroids during initial MBM tx. At a median FU of 13.4 (0.0 - 82.8) months (mos), the median OS was 15.1 mos, and 1- and 2-year OS rates were 56% and 40%. Notably, gender, time to MBM dx, and BRAF status were not associated with OS (univariate analysis). On MV analysis, clinical features associated with worse OS included increased age, increased primary tumor thickness, elevated LDH, > 3 MBMs, +LMD, +symptoms, and prior tx with IMT. Among tx used at any time after MBM dx, WBRT (HR 1.9, 95% CI 1.5-2.5) was associated with worse OS; SRS (HR 0.7, 95% CI 0.5-0.8) and IMT (HR 0.6, 95% CI 0.5-0.8) were associated with improved OS. Conclusions: In one of the largest cohorts of MBM pts described to date, OS has improved in MBM pts in the current era. Prognostic factors for OS include pt age, primary tumor and MBM features, prior tx, and tx for MBM. Additional analyses to assess the interaction of tx, disease features, and OS will be presented.

Incidence, timing, and predictors of CNS metastasis in patients (Pts) with clinically localized cutaneous melanoma (CM)

9580

Background: Surveillance for CNS metastasis (mets) is not routinely performed in pts with clinically localized CM. Improved understanding of the incidence, timing and risk factors for the development of CNS metastasis in these pts may inform surveillance strategies. Methods: Under an IRB-approved protocol, demographics, tumor characteristics, and clinical events were collected for pts diagnosed from 1998 to 2019 with AJCC 8th edition stage I or II CM at MD Anderson Cancer Center. Dates of initial diagnosis, regional, distant non-CNS, and CNS mets were recorded. Symptoms and the extent of disease (brain, LMD, both) were recorded for pts with CNS mets. Cumulative incidence of distant mets (CNS and non-CNS) was determined using the competing risks method, including death; pts without CNS mets and alive at last follow-up were censored. Differences in cumulative incidence between groups were assessed using Gray’s test. Associations between measures of interest and cumulative incidence were determined using proportional subdistribution hazards regression models. All statistical tests used a significance level of 5%. Results: 5,179 Stage I-II CM pts were identified. At a median follow up of 82 (0.0-268.8) months, 703 (13.6%) pts were diagnosed with distant mets, including 355 (6.9%) with CNS mets. Cumulative incidence of CNS mets was 0%, 2%, and 5% at 1, 2, and 5 years, respectively. Among pts with distant mets, the first site of distant mets was CNS only for 29 (4%), non-CNS only for 557 (79%), and both for 116 (17%) pts. At initial diagnosis of CNS mets, 195 (55%) pts were asymptomatic, and 46 (13%) had no active extracranial disease. Median time to any distant met was longer for pts who were diagnosed with CNS mets [40.0 (1.9-238.0) months] vs pts diagnosed with non-CNS mets only [31.4 (1.1-185.7) months, p < 0.001]. On multivariable analysis, risk of CNS mets was significantly associated with primary tumor location of scalp [Hazard Ratio (HR) 3.4, 95% Confidence interval (CI) 1.9-5.9], head/neck (HR 3.3, 95% CI 2.0-5.3), or trunk (HR 2.3, 95% CI 1.5-3.5) (vs upper extremity); acral lentiginous melanoma subtype (HR 2.0, 95% CI 1.2-3.6) (vs superficial spreading); increased T category (T2 HR 1.5, 95% CI 1.1-2.2; T3 HR 1.9, 95% CI 1.2-3.0; T4 HR 2.1, 95% CI 1.1-3.8; vs T1), Clark level (CL) (CL4 HR 2.1, 95% CI 1.2-3.7 vs CL2), and mitotic rate (MR) (MR 5-9/mm2 HR 2.1, 95% CI 1.5-3.0; MR > 9/mm2 HR 2.0, 95% CI 1.3-3.0; vs MR 0-4/mm2). While high ( > 9/mm2) MR was associated with increased risk of CNS and non-CNS mets, intermediate (5-9/mm2) was associated with CNS mets only. Conclusions: Primary tumor location, tumor thickness, and MR were strongly associated with risk of CNS mets. MR rate was more strongly associated with risk of CNS than non-CNS mets. Validation in independent cohorts may provide evidence to support CNS surveillance strategies in select pts with stage I-II CM who are deemed high risk for CNS mets.

A phase 1b study of nivolumab in patients with autoimmune disorders and advanced malignancies (AIM-NIVO)

TPS2676

Background: Nivolumab is an anti-PD1 monoclonal antibody approved for treatment of an increasing number of solid tumors and hematological malignancies. However, patients (pts) with history of autoimmune disorders are excluded from the majority of clinical trials testing immune-checkpoint inhibitors (ICI) such as anti-PD1/anti-PD-L1 antibodies. Consequently, the risks of flare ups, worsening of pre-existing autoimmune disorders or risk of de-novo immune related adverse events (irAEs) in pts with dysfunctional immune systems and tumor types who otherwise stand to benefit from ICI therapy are largely unknown, posing a challenge for oncologists. We are conducting a phase Ib study to test the hypothesis that nivolumab can be safely administered to pts with varying severity of Dermatomyositis, Systemic Sclerosis, Rheumatoid Arthritis, Systemic Lupus Erythematosus, Inflammatory Bowel Disease, Multiple Sclerosis and other autoimmune disorders (AIM-Nivo). Methods: AIM-Nivo is an open-label, multi-center ongoing phase Ib study with nivolumab 480mg IV every 28 days in pts with autoimmune diseases and advanced malignancies (NCT03816345). The study has autoimmune disease-specific cohorts overseen by a multidisciplinary group of experts. The primary objective is to assess the overall safety and toxicity profile of nivolumab in pts with autoimmune disorders and advanced malignancies. Secondary objectives are to evaluate the antitumor efficacy; the impact of nivolumab on the autoimmune disease severity indices; and to explore potential biomarkers of response, resistance, or toxicity for each of the autoimmune disease-specific cohorts. Key overall inclusion criteria include age ≥18 years, histologically confirmed advanced or metastatic malignancies in which ICI are approved or have shown clinical activity. Key overall exclusion criteria include prior therapy with anti-PD-1/PD-L1 antibodies. Specific eligibility criteria are defined for each disease-specific cohort. For each autoimmune disorder, severity level of the disease as defined by disease-specific severity indices will be assessed, and up to a total of 12 pts will be included in each disease cohort at each severity level (max 36 pts per cohort). Primary endpoints are dose-limiting toxicities, adverse events (AEs) and serious AEs. Continuous monitoring of toxicity will be conducted. Key secondary endpoints are best objective response per RECIST1.1; progression free and overall survival; and cohort specific tumor tissue, blood, and non-tumor tissue-based biomarkers. The AIM-Nivo trial opened in May 2019 and is enrolling pts through the National Cancer Institute Experimental Therapeutics Clinical Trials Network (ETCTN), Early Drug Development Opportunity Program (EDDOP), and Create Access to Targeted Cancer Therapy for Underserved Populations (CATCH-UP) sites. Clinical trial information: NCT03816345.

Intrathecal (IT) and intravenous (IV) nivolumab (N) for metastatic melanoma (MM) patients (pts) with leptomeningeal disease (LMD)

9519

Background: MM pts with LMD have a dismal prognosis, with median overall survival (OS) < 3 months, no approved therapies and extremely limited clinical trial options. We previously reported initial safety findings from an open label, single arm, single center phase I/IB trial (NCT03025256), in which IT and IV N were well tolerated, without any CNS-specific or unexpected toxicity. Here we report an update on safety and maximum tolerated dose (MTD) for all patients enrolled, and efficacy for the completed dose cohorts. Methods: MM patients aged >18 with evidence of LMD by MRI and/or CSF cytology, ECOG PS ≤2 were treated with IT and IV N. Dexamethasone ≤4mg/daily and concurrent BRAF/MEK inhibitor(i) treatment was allowed. For cycle 1, IT N was administered via intraventricular reservoir on day (D)1. For subsequent cycles (every 14 days), pts received IT N on D1, followed by IV N 240 mg on D2. IT N doses evaluated were 5, 10, 20 mg and 50 mg. Blood and CSF were collected at multiple time points for translational research. The primary objectives of this first-in-human study were to determine the safety and MTD of IT N given with IV N in MM pts with LMD. Bayesian mTPI methodology was used to define the MTD. Results: To date, 23 pts have been treated: two at 5, three at 10, fourteen at 20 mg and four at 50 mg IT N. Median age at LMD diagnosis was 42 (28-73); 12 pts are male. All pts had radiographic evidence of LMD and neurological symptoms; 14 pts had positive CSF cytology at baseline. 21 pts received prior therapies for their metastatic melanoma: anti-PD1 (n = 19), BRAFi/MEKi (n = 14), chemo (n = 2), IT IL2 (n = 4) other (n = 2). 19 pts had prior XRT, including whole brain RT (n = 7). Two pts were treatment-naïve. The median number of IT N doses was five (1- 66). The combination regimen was well tolerated by all evaluable pts (n=23), with only five pts (22%) experiencing gr 3 AEs, and no reported gr 4 or 5 toxicities. Nausea (30%), diarrhea (26%), and rash (22%) were the most common AEs. Eight pts (23%) experienced AEs after IT N administration, all gr 1. Initial efficacy analysis included only pts (n=19) treated with first three dose levels (5-20mg). Median follow-up for these pts is 4.5 months (mos) (1.1, 31.5 mos) and median OS is 63 % at 3 mos, 42 % at 6 mos and 30% at 12 mos. Conclusions: The trial demonstrates the feasibility and safety of IT administration of modern immunotherapy for MM pts with LMD. No unexpected systemic or neurological toxicity was observed with 20mg IT N. 2 additional patients are required to complete the 50mg IT N cohort. OS rates at 6 and 12 mos are encouraging and support further evaluation of IT administration of immunotherapy agents for pts with MM and LMD. Final presentation will include results of LMD for all dose cohorts, composite response assessment and comparative analysis of longitudinal CSF samples to assess immunologic effects. Clinical trial information: NCT03025256.

Treatment outcomes in patients (pts) with melanoma brain metastases (MBM) treated with systemic therapy: A systematic literature review (SLR) and meta-analysis

9561

Background: The introduction of immunotherapy and targeted therapy has revolutionized the treatment landscape for metastatic melanoma. However, clinical trial data in pts with MBM are scarce; here we summarize the available clinical evidence. Methods: An SLR was conducted by searching EMBASE, MEDLINE, and the Cochrane Central Register of Controlled Trials databases through November 13, 2020. When available, Kaplan-Meier (K-M) curves for overall survival (OS) were digitized and converted to pseudo-individual pt data using the Guyot algorithm. A meta-analysis of the pooled K-M curves was performed for selected interventions, including immunotherapies and targeted therapies. Median OS was calculated either through the meta-analysis of K-M curves or as a weighted average of median OS (table). When interventions were reported in only 1 study, the value reported was used instead of the weighted average and compared qualitatively with the other results. Results for treatment modalities other than systemic agents will also be presented. Results: The SLR included 70 publications that evaluated systemic therapies in pts with MBM for qualitative evidence synthesis: 12 pertaining to 7 randomized controlled trials, 55 pertaining to 46 single-arm studies, and 3 involving nonrandomized comparative studies. The pt population was highly heterogeneous with respect to prior therapies, pt characteristics, and neurological symptoms. For the meta-analysis, a total of 25 K-M curves from 12 studies representing 6 interventions and 1043 pts were digitized. Based on the pooled K-M curves, median OS was numerically longer with nivolumab plus ipilimumab (NIVO + IPI; 28.3 mo; 95% CI, 19.7-31.9) than with the other interventions (range 5.7-11.8 mo; table). Similar OS benefit was also observed with NIVO + IPI when the weighted average of the median was used (in a long-term study, median OS was 29.2 mo) compared with the other interventions. Conclusions: Given the lack of comparative clinical trial data in pts with MBM, there remains an unmet need to determine the best approach to treat these pts. This analysis suggested a clinical advantage with NIVO + IPI compared with other systemic agents analyzed. The heterogeneity of the available data added uncertainty to our treatment assessments. Therefore, these findings warrant further research into the best approach to improve outcomes in pts with MBM.[Table: see text]

Neoadjuvant and adjuvant nivolumab (nivo) with anti-LAG3 antibody relatlimab (rela) for patients (pts) with resectable clinical stage III melanoma

9502

Background: Neoadjuvant therapy (NT) for pts with clinical stage III melanoma remains an active area of research interest. Recent NT trial data demonstrates that achieving a pathologic complete response (pCR) correlates with improved relapse-free (RFS) and overall survival (OS). Checkpoint inhibitor (CPI) NT with either high or low dose ipilimumab and nivolumab regimens produces a high pCR rate of 30-45% but with grade 3-4 toxicity rate of 20-90%. In metastatic melanoma (MM), the combination of nivo with rela (anti Lymphocyte Activation Gene-3 antibody) has demonstrated a favorable toxicity profile and responses in both CPI-naïve and refractory MM. We hypothesized that NT with nivo + rela will safely achieve high pCR rates and provide insights into mechanisms of response and resistance to this regimen. Methods: We conducted a multi-institutional, investigator-initiated single arm study (NCT02519322) enrolling pts with clinical stage III or oligometastatic stage IV melanoma with RECIST 1.1 measurable, surgically-resectable disease. Pts were enrolled at 2 sites and received nivo 480mg IV with rela 160mg IV on wks 1 and 5. Radiographic response (RECIST 1.1) was assessed after completion of NT; surgery was conducted at wk 9 and specimens were assessed for pathologic response per established criteria. Pts received up to 10 additional doses of nivo and rela after surgery, with scans every 3 mo to assess for recurrence. The primary study objective was determination of pCR rate. Secondary objectives included safety, radiographic response by RECIST 1.1, event-free survival (EFS), RFS, and OS analyses. Blood and tissue were collected at baseline, at day 15, day 28, and at surgery for correlative analyses. Results: A total of 30 pts (19 males, median age 60) were enrolled with clinical stage IIIB/IIIC/IIID/IV (M1a) in 18/8/2/2 pts, respectively. 29 pts underwent surgery; 1 pt developed distant metastatic disease while on NT. pCR rate was 59% and near pCR ( < 10% viable tumor) was 7% for a major pathologic response (MPR, pCR + near pCR) of 66%. 7% of pts achieved a pPR (10-50% viable tumor) and 27% pNR (≥50% viable tumor). RECIST ORR was 57%. With a median follow up of 16.2 mos, the 1 -year EFS was 90%, RFS was 93%, and OS was 95%. 1-year RFS for MPR was 100% compared to 80% for non-MPR pts (p = 0.016). There were no treatment related gr 3/4 AEs that arose during NT; 26% of pts had a gr 3/4 AE that began during adjuvant treatment. Conclusions: Neoadjuvant and adjuvant treatment with nivo and rela achieved high pCR and MPR rates with a favorable toxicity profile in the neoadjuvant and adjuvant settings. Pts with MPR had improved outcomes compared to non-MPR pts. Translational studies to discern mechanisms of response and resistance to this combination are underway. Clinical trial information: NCT02519322.

Phase II Study of TRIplet combination Nivolumab (N) with Dabrafenib (D) and Trametinib (T) (TRIDeNT) in patients (pts) with PD-1 naïve or refractory BRAF-mutated metastatic melanoma (MM) with or without active brain metastases

9520

Background: Targeted therapies (TT) & immunotherapies (IMT) have improved survival for pts with BRAF V600 mutated stage IV MM, however many pts still progress and ultimately die from their disease. Preclinical data support the rationale for combining TT and IMT, but trials evaluating triplet combinations in IMT-naïve pts have reported mixed results. Notably, pts with untreated brain metastases (BM) were excluded from prior triplet trials and have a median PFS of 5.6 months when treated with TT. Further, there remains an unmet need for effective therapies for pts after IMT failure, as retrospective studies have reported short median PFS (5 mos) for TT in this setting. We hypothesized that N in combination with DT is safe and will demonstrate clinical activity in BRAF-mutated pts naïve or refractory to PD1 therapy and in pts with BM. Methods: We conducted a single arm phase II study (NCT02910700) of NDT in pts with BRAF-mutated, unresectable stg III or stg IV MM. Prior IMT was allowed, but prior BRAF/MEKi was not. Pts with untreated BM and asymptomatic or mildly symptomatic/requiring steroids were also allowed. Pts received 3mg/kg IV Q2wks of N (later amended to 480 mg IV Q4wks), 150mg PO BID of D and 2mg PO QD of T, all starting on Day 1. The primary objective was to determine safety and efficacy (ORR by RECIST 1.1). Monitoring for safety and futility using Bayesian stopping rules was performed. Longitudinal tissue and blood samples were collected to perform correlative analyses. Results: Following a 6 pt safety run-in with no observed DLTs, 27 pts were treated w NDT. 17 pts were PD1 refractory, 10 were PD-1 naïve. 10 of these 27 pts had a history or presence of BM, including active BM. Median follow up was 18.4 months (range 3.2-45.9). ORR in 26 evaluable pts was 92% (3 CR, 21 PR). Among the PD1 refractory pts evaluable for response (n = 16), ORR was 88% (2 CRs, 12 PR). All 10 evaluable PD-1 naïve pts achieved a response. 4 of 7 evaluable pts w BM achieved an intracranial response (57%), including 2 CRs. The median PFS for all pts was 8.5mos (8.5mos in PD1 naïve pts, 8.2mos in PD1 refractory pts). Median PFS for pts without BM was 8.5mos, 8.0 mos for those with BM. Median OS for all pts was not reached, and no statistically significantly difference in OS by PD1 exposure or presence of BM. 78% of pts experienced treatment related grade 3/4 AEs and 6 pts (22%) discontinued all 3 drugs due to toxicities. Conclusions: NDT at full doses of all 3 agents has a toxicity profile consistent with previously reported triplet combinations and shows promising clinical activity in pts with IMT refractory disease and with BM. There were no significant differences in outcomes between pts with and without BM. Translational studies to delineate predictors and mechanisms of response and resistance are ongoing. Clinical trial information: NCT02910700.

A phase 1 study of NY-ESO-1 vaccine + anti-CTLA4 antibody Ipilimumab (IPI) in patients with unresectable or metastatic melanoma

Ipilimumab (IPI) can enhance immunity to the cancer-testis antigen NY-ESO-1. A clinical trial was designed to assess safety, immunogenicity, and clinical responses with IPI + NY-ESO-1 vaccines and effects on the tumor microenvironment (TME). Patients with measurable NY-ESO-1⁺ tumors were enrolled among three arms: A) IPI + NY-ESO-1 protein + poly-ICLC (pICLC) + incomplete Freund’s adjuvant (IFA); B) IPI + NY-ESO-1 overlapping long peptides (OLP) + pICLC + IFA; and C) IPI + NY-ESO-1 OLP + pICLC. Clinical responses were assessed by irRC. T cell and Ab responses were assessed by ex vivo IFN-gamma ELIspot and ELISA. Tumor biopsies pre- and post-treatment were evaluated for immune infiltrates. Eight patients were enrolled: 5, 2, and 1 in Arms A-C, respectively. There were no DLTs. Best clinical responses were SD (4) and PD (4). T-cell and antibody (Ab) responses to NY-ESO-1 were detected in 6 (75%) and 7 (88%) patients, respectively, and were associated with SD. The breadth of Ab responses was greater for patients with SD than PD (p = .036). For five patients evaluable in the TME, treatment was associated with increases in proliferating (Ki67⁺) CD8⁺ T cells and decreases in RORγt⁺ CD4⁺ T cells. T cell densities increased for those with SD. Detection of T cell responses to NY-ESO-1 ex vivo in most patients suggests that IPI may have enhanced those responses. Proliferating intratumoral CD8⁺ T cells increased after vaccination plus IPI suggesting favorable impact of IPI plus NY-ESO-1 vaccines on the TME.

List of Abbreviations: Ab = antibody; CTCAE = NCI Common Terminology Criteria for Adverse Events; DHFR/DHRP = dihydrofolate reductase; DLT = Dose-limiting toxicity; ELISA = enzyme-linked immunosorbent assay; IFA = incomplete Freund’s adjuvant (Montanide ISA-51); IFNγ = Interferon gamma; IPI = Ipilimumab; irRC = immune-related response criteria; mIFH = multispectral immunofluorescence histology; OLP = NY-ESO-1 overlapping long peptides; PBMC = peripheral blood mononuclear cells; PD = Progressive disease; pICLC = poly-ICLC (Hiltonol), a TLR3/MDA-5 agonist; RLT = Regimen-limiting Toxicity; ROI = regions of interest; RT = room temperature; SAE = serious adverse event; SD = stable disease; TEAE = treatment-emergent adverse events; TLR = toll-like receptor; TME = tumor microenvironment; TRAE = treatment-related adverse events.

A phase II study evaluating atezolizumab (A), cobimetinib (C), and vemurafenib (V) in patients (pts) with BRAF-mutant melanoma and central nervous system (CNS) metastases (mets)

TPS10081

Background: CNS mets, a common complication of melanoma, are associated with poor survival prognosis (median of 4-5 months). The rationale for combining PD-L1 pathway blockade using atezolizumab (A) with the small molecule BRAF pathway–targeted inhibitors cobimetinib (C) and vemurafenib (V) for the treatment of BRAFV600 mutation–positive melanoma is based on preclinical and translational evidence supporting the synergistic antitumoral effects of these approaches. Recently, the phase 3 IMspire150 study (NCT02908672) demonstrated improved progression-free survival outcomes with A + C + V vs C + V. Methods: This phase 2 study (NCT03625141) is currently evaluating A + C + V in pts with BRAFV600 mutation–positive advanced melanoma and CNS mets. The study originally included a parallel cohort evaluating A + C in pts with BRAFV600wild-type advanced melanoma and CNS mets. This cohort was closed at an enrollment of 15 pts after the primary analysis of the phase 3 IMspire170 study (NCT03273153), which showed no added benefit with A + C vs pembrolizumab in pts with BRAFV600 wild-type disease. Eligible pts are aged ≥18 years with histologically confirmed melanoma and magnetic resonance imaging–confirmed brain mets ≥5 mm in at least 1 dimension. In addition, pts should not have received prior systemic treatment for metastatic disease; they were required to have ECOG performance status ≤2 and adequate hematologic and end organ function. Prior stereotactic or surgical therapy of ≤10 brain mets is allowed. The primary endpoint is intracranial objective response rate (ORR) with A + C + V in BRAFV600mutation–positive melanoma as assessed by an independent review committee. Key secondary endpoints include investigator-assessed intracranial ORR, extracranial ORR, overall ORR, safety, and quality of life. Exploratory biomarker analyses are planned. The sample size for the cohort will be approximately 60 pts. No formal statistical hypothesis is being tested in this study. The primary study analysis and the analyses of all efficacy endpoints and safety summaries will be based on data collected ≤6 months after the last pt is enrolled. Clinical trial information: NCT03625141.

Radiomic signatures to predict response to targeted therapy and immune checkpoint blockade in melanoma patients (pts) on neoadjuvant therapy

10067

Background: Metastatic melanoma pt outcomes have been revolutionized by targeted therapy (TT) and immune checkpoint blockade (ICB), which are now being evaluated in the neoadjuvant (neoadj) setting. While tumor-based biomarkers may help predict response, predictors of response obtained by less invasive strategies could greatly benefit pt care and allow real-time treatment response monitoring. Radiomic signatures derived from computerized tomography (CT) images have recently been shown to predict response to ICB in stage IV pts. However, the association of radiomic features with pathological response following neoadj therapy has not been assessed. We sought to determine if radiomic assessment predicts pCR in pts receiving neoadj TT and ICB. Methods: We collected data for a cohort of melanoma pts with locoregional metastases who were treated with neoadj TT (n = 33) or ICB (n = 30). Pts received systemic therapy for 8-10 weeks prior to planned surgical resection. Responses were evaluated radiographically (RECIST 1.1) and via pathological assessment (evaluating for pathologic complete response; (pCR) versus < pCR). Thirty two pts (19 ICB; 13 TT) were included in the radiomics analysis based on the availability of appropriate CT imaging. A total of 310 unique radiomic features (10 histogram-based and 300 second-order texture features) were calculated from each extracted volume of interest (VOI). Feature extraction was performed on baseline and initial on-treatment pre-operative CT scans. Features associated with pCR were assessed using a feature selection approach based on Least Absolute Shrinkage and Selection Operator (LASSO). Selected features were used to build a classification model for prediction of pCR to ICB or TT. Leave-One-Out Cross-Validation was performed to evaluate the robustness of the estimates. Results: Out of 310 radiomic features, three features measured at baseline were able to predict a pCR to neoadj ICB or TT with sensitivity, specificity and accuracy of 100%, though these signatures were non-overlapping. In the on-treatment pre-operative scans, 3 distinct features (also non-overlapping and distinct from the predictive pre-treatment signatures) also predicted pCR to ICB and TT with 100% sensitivity, specificity and accuracy. Conclusions: Radiomic signatures in baseline and on-treatment CT scans accurately predict pCR in melanoma pts with locoregional metastases treated with neoadj TT or ICB. These provocative findings warrant further investigation in larger, independent cohorts.

Effect of first-line spartalizumab + dabrafenib + trametinib on immunosuppressive features detected in peripheral blood and clinical outcome in patients (pts) with advanced BRAF V600–mutant melanoma

10034

Background: Spartalizumab + dabrafenib + trametinib has previously shown a high response rate of 78% (28 of 36 pts), with a complete response (CR) rate of 42%. A correlative analysis of gene expression signatures (GES)/pathways using whole-transcriptome RNA-seq data from tissue showed that pts with a CR had significantly lower expression levels of immunosuppressive factors in the tumor microenvironment (TME) at baseline (BL). Here we analyze BL peripheral blood markers in the same cohort of pts to assess whether liquid markers can also predict response and clinical outcome to spartalizumab + dabrafenib + trametinib. Methods: The Phase III COMBI-i study (NCT02967692) is evaluating spartalizumab + dabrafenib + trametinib in pts with previously untreated BRAF V600–mutant unresectable or metastatic melanoma. In parts 1 (safety run-in; n = 9) and 2 (biomarker cohort; n = 27), blood and tissue samples were collected at BL, on treatment after 2-3 wk and 8-12 wk, and at disease progression. Lactate dehydrogenase (LDH) and other blood-based markers (including cytokine profiling [n = 45] and blood RNA-seq [114 signatures]) were assessed in all 36 pts. Pts were divided into 2 groups of 24 and 12 pts based on progression-free survival (PFS) of > 1 or < 1 y. Results: In addition to LDH, previously described blood markers such as neutrophil to lymphocyte ratio (NLR) and plasma IL-8 were identified among other neutrophil and immunosuppressive features as top candidates associated with PFS > 1 y. Low plasma IL-8 levels were also associated with CR, and multivariate models suggested that IL-8 may add independent predictive value to LDH and NLR for PFS > 1 y and CR. Pts with high IL-8 levels in the circulation were characterized by high neutrophil chemokine signaling (ρ = 0.553) and high neutrophil markers (ρ = 0.466) in the tumor as measured by RNA-seq GES levels. We observed a decrease in plasma IL-8 levels from BL upon treatment with spartalizumab + dabrafenib + trametinib. Conclusions: Our peripheral blood marker analysis confirmed recent findings from tissue samples that intratumoral immunosuppressive features may preclude a CR and are associated with poor outcomes. High BL plasma IL-8 levels may be associated with an immunosuppressive TME. Further validation is warranted; the randomized placebo-controlled part 3 of COMBI-i is ongoing. Clinical trial information: NCT02967692.

Preliminary results of a phase II study of neoadjuvant checkpoint blockade for surgically resectable undifferentiated pleomorphic sarcoma (UPS) and dedifferentiated liposarcoma (DDLPS)

11505

Background: is a randomized, phase II non-comparative trial evaluating the efficacy of neoadjuvant checkpoint blockade [nivolumab (N) or ipilimumab/ nivolumab (I/N)] in patients (pts) with surgically resectable retroperitoneal DDLPS or extremity/truncal UPS treated with concurrent neoadjuvant radiation therapy (RT, UPS only). Methods: Primary endpoint was pathologic (path) response. Secondary endpoints were safety, RECIST response, recurrence-free survival, overall survival and patient-reported outcomes. Biospecimens (tumor, blood, fecal microbiome) at baseline, on therapy, and at time of surgery were collected and will be assessed for immune-based prognostic biomarkers. We assessed correlation between radiographic and pathologic response by linear regression. Correlative analyses includes assessment of tumor PD-L1 expression, characterization of tumor immune infiltrates by multiplex immunohistochemistry, and transcriptomic and genomic analyses. Results: Of the 25 pts enrolled; 24 are evaluable for response (14 DDLPS, 9 UPS). Clinical activity was variable by histologic subtype and treatment with RT. Median path response in the UPS cohort was 95% [95% CI 85–99] and was similar between the N/RT and I/N/RT groups (Table). Median path response in the DDLPS cohort was 22.5% [95% CI 85–99; Table]. Median change in tumor size (radiographic response) was -4% and +9% in the UPS and DDLPS cohorts, respectively. There was no correlation between path response and radiographic response (R2 0.0309; p = 0.43). Of 8 pts with path response ≥ 85%, there was 1 partial response, 5 stable disease and 2 progressive disease by RECIST criteria. There was 1 delay to surgery due to grade 3 hyperbilirubinemia (Arm B). There was no difference in toxicity between N/RT and I/N/RT. Conclusions: N/RT and I/N/RT have significant clinical activity in UPS; more than expected compared to historic controls. Toxicity profiles were as expected and the majority of patients underwent resection without delay. Larger studies evaluating N/RT in UPS are warranted given the significant path response in this cohort. RECIST was not associated with path response and better markers of on-treatment clinical activity are needed. Correlative analyses that may guide combination strategies are ongoing and will be presented at the meeting. Clinical trial information: NCT03307616 .

Efficacy of immune checkpoint inhibitors for the treatment of metastatic melanoma (MM) in patients with concurrent chronic lymphocytic leukemia (CLL)

e22044

Background: Patients with CLL have immune impairment with abnormalities in T-cell subset composition and immune synapse formation. The impact of these defects on response to immune checkpoint inhibitors (CPI) is not known. Given the high incidence of melanoma in patients with CLL we sought to evaluate the response to CPI in patients with concomitant MM and CLL. Methods: Retrospective analysis of 24 patients (pts) with concurrent CLL and MM who received a total of 38 CPI therapies between July 1997 and July 2019. Primary objective was to determine objective response rate (ORR), defined as complete response (CR) or partial response (PR) by RECIST1.1. Secondary outcomes included event-free survival; overall survival (OS), and duration of response (DOR). Results: The median age at CLL and melanoma diagnosis was 62 and 63 years, respectively. 71% of patients were male. Most presented with early stage CLL at diagnosis (67%), 60% had mutated IGVH, and 47% had deletion of 13q by FISH. 71% remained on observation for their CLL. Median time from melanoma diagnosis to CPI initiation was 13.5 months. 83% had stage IV MM and 17% stage III MM at the time of therapy. 17% had increased LDH. The most common melanoma mutations were BRAF(35%), BRAFV600 (26%), TP53 (30%) and NRAS (26%). Median follow up was 37 months and the ORR was 24% (Table). Median DOR was 41 months and median OS is 26.4 months. Immune-mediated adverse events occurred in 42%, including 13% fever, 11% thrombotic events, 8% endocrine dysfunction. 13 pts are alive and 11 pts died (8 pts due to MM progression). There were no significant changes in absolute lymphocyte counts during CPI therapy. 2 pts received CPI while on ibrutinib or ibrutinib+venetoclax therapy with ongoing CLL responses. Conclusions: Our experience indicates that CPIs can be effective for the treatment of MM in patients with concurrent CLL, achieving durable responses. Immuno-mediated toxicities were frequently observed. A lower ORR was observed in first-line CPI in MM, however the numbers of pts are small. Further studies are needed to determine if initial or concurrent treatment for CLL could improve CPI outcomes and survival. Additional studies evaluating T cells function and tissue infiltration in these patients are ongoing. [Table: see text]

Safety results from phase I/II study of the PI3Kβ inhibitor GSK2636771 (G) in combination with pembrolizumab (P) in patients (pts) with PD-1 refractory metastatic melanoma (MM) and PTEN loss

e22000

Background: Checkpoint inhibitors (CPI) have improved survival and long-term disease control in 35-40% of pts with MM. Many pts derive no clinical benefit or progress after an initial response. Our group and others have shown that loss of the tumor suppressor protein PTEN occurs in multiple cancers, up to 30% of MM pts, activates the PI3K pathway, and correlates with decreased MM response rates to CPI and decreased T cell infiltrates. In PTEN-null MM preclinical models, inhibition of the PI3Kβ-subunit with GSK2636771 (G) was superior to pan-PI3K inhibitors, increased intratumoral T cell infiltration and the activity of CPI. To test our hypothesis that PI3Kβi reverses resistance to CPI, we are conducting a Phase I/II study (NCT03131908) combining G with P in PD-1 refractory pts with PTEN loss. Methods: The primary objective of Ph I portion is to determine the Maximum-Tolerated Dose (MTD) and Recommended Phase II Dose (RP2D) of G with P in PD-1 refractory pts (including melanoma, endometrial, TNBC, and prostate cancers) with PTEN loss. Pts receive P at 200mg IV q 3 wks. G starting dose level (DL1) was 300 mg PO qd for 21 days and escalated to 400 mg PO qd (DL2) using a 3+3 design. A dose level -1 (DL-1) (200 mg PO qd) was also included in the event of unacceptable toxicities at higher doses. Ph II will accrue 35 pts at the RP2D. This study is continuously monitored for toxicity and futility. The primary objectives of Ph II are safety, tolerability, and efficacy of the combination as defined by Objective Response Rate (ORR) by RECIST 1.1. Secondary Objectives include the PKs of G and PD effects in tumor tissue as measured by pathway inhibition and T cell trafficking into tumors. Results: 13 pts have been treated, 6 at the 300mg (DL1), 5 at 400mg (DL2), and 2 at 200 mg (DL-1). One DLT (grade 3 hypocalcemia) was observed at the 300mg dose. Two DLTs were observed in the 400mg cohort, one of which was AKI requiring dialysis and the other was a Gr 3 rash. Based on this experience and additional safety data from GSK regarding renal toxicity, DL-1 was declared RP2D at 200mg. 2 pts at the RP2D have passed the DLT evaluation period without toxicities. Conclusions: The combination of G and P is being explored at the RP2D of 200 mg. Renal toxicity precluded higher doses. No objective responses have been observed although 2 pts have experienced prolonged clinical benefit including a MM pt with 27% decrease in tumor burden. Through longitudinal biopsies, we aim to better understand the role PTEN loss plays when targeted in combination with CPI. Clinical trial information: NCT03131908.

A phase Ib study of nivolumab in patients with autoimmune disorders and advanced malignancies (AIM-NIVO)

TPS3158

Background: Immune checkpoint inhibitors (ICI) such as anti-PD-1/PD-L1 antibodies have become a pivotal approach to cancer therapy. Nivolumab is an anti-PD1 antibody approved for an increasing number of solid tumors and hematological malignancies. However, patients (pts) with history of autoimmune disorders are excluded from the majority of clinical trials testing ICI. Consequently, the risks of flares and worsening of pre-existing autoimmune disorders in pts with tumor types who otherwise stand to benefit from ICI therapy are largely unknown, posing a challenge for oncologists. We are conducting a phase Ib study to test the hypothesis that nivolumab can be safely administered to pts with varying severity of Dermatomyositis, Systemic Sclerosis, Rheumatoid Arthritis, Systemic Lupus Erythematosus, Inflammatory Bowel Disease, Multiple Sclerosis, Sjögren's Syndrome and Other Autoimmune Disorders (AIM-Nivo). Methods: AIM-Nivo is an open-label, multi-center ongoing phase Ib study with nivolumab 480mg IV every 28 days in pts with autoimmune diseases and advanced malignancies (NCT03816345). The study has autoimmune disease-specific cohorts overseen by a multidisciplinary group of experts. The primary objective is to assess the overall safety and toxicity profile of nivolumab in pts with autoimmune disorders and advanced malignancies. Secondary objectives are to evaluate the antitumor efficacy, the impact of nivolumab on the autoimmune disease severity indices, and to explore potential biomarkers of response, resistance or toxicity. Key overall inclusion criteria include age ≥18 years, histologically confirmed advanced malignancies in which ICI are approved or have shown clinical activity. Key overall exclusion criteria include prior therapy with anti-PD-1/PD-L1 antibodies. Specific eligibility criteria are defined for each disease-specific cohort. For each autoimmune disorder, severity level of the disease as defined by disease-specific severity indices will be assessed, and up to a total of 12 pts will be included in each disease cohort at each severity level. Primary endpoints are dose-limiting toxicities, adverse events (AEs) and serious AEs. Continuous monitoring of toxicity will be conducted. Key secondary endpoints are best objective response, progression free and overall survival and cohort specific tumor tissue, blood and non-tumor tissue-based biomarkers. The AIM-Nivo trial opened in May 2019 and is enrolling pts through the National Cancer Institute Experimental Therapeutics Clinical Trials Network (ETCTN). Clinical trial information: NCT03816345 .

The anti–PD-1 antibody spartalizumab in combination with dabrafenib and trametinib in advanced BRAF V600–mutant melanoma: Efficacy and safety findings from parts 1 and 2 of the Phase III COMBI-i trial

10028

Background: Treatment (tx) with checkpoint inhibitors or targeted therapy improves outcomes in patients (pts) with BRAF V600–mutant advanced melanoma; however, many pts subsequently progress and die. Preliminary evidence suggests that targeted therapy may enhance the impact of checkpoint inhibitors and improve efficacy compared with either treatment alone. Methods: COMBI-i is investigating first-line spartalizumab 400 mg every 4 wk + dabrafenib 150 mg twice daily + trametinib 2 mg once daily in pts with unresectable or metastatic BRAF V600–mutant melanoma (NCT02967692). We report efficacy and safety data from parts 1 (run-in cohort) and 2 (biomarker cohort), with a median follow-up of 24.3 mo. Response was assessed per RECIST v1.1. The randomized part 3 is ongoing. Results: 36 pts were enrolled (part 1: n = 9; part 2: n = 27); 20 (56%) had stage IV M1c disease and 15 (42%) had elevated lactate dehydrogenase (LDH) levels (≥ upper limit of normal). At the data cutoff (August 19, 2019), tx was ongoing in 10 pts (28%). The confirmed investigator-assessed objective response rate (ORR) was 78% (n = 28), with 16 complete responses (CRs; 44%) and 12 partial responses (33%). Median duration of response (DOR; 10/28 responders with events) was not reached (NR); 24-mo DOR rate was 53.4% (95% CI, 29%-73%). Median progression-free survival (PFS) was 22.7 mo; 24-mo PFS rate was 41.4% (95% CI, 23%-59%). At the cutoff, median overall survival (OS) was NR, with a 24-mo OS rate of 74.1% (95% CI, 56%-86%). In pts with elevated LDH, ORR was 67%, with 4 CRs (27%); median PFS was 10.7 mo (95% CI, 4.6-19.1 mo), and median OS was NR. The estimated 24-mo PFS and OS rates in these pts were 26.7% and 52.5%, respectively. All pts had ≥ 1 tx-related adverse event (TRAEs); 26 (72%) had grade ≥ 3 TRAEs. The most common grade ≥ 3 TRAEs were pyrexia (17%), increased lipase (11%), neutropenia (11%), increased blood creatine phosphokinase (8%), and increased γ-glutamyltransferase (8%). AEs leading to discontinuation of all 3 study drugs occurred in 6 pts (17%). All-causality grade ≥ 3 AEs requiring immunosuppressive medication occurred in 19 pts (53%). One pt died of cardiac arrest that was not considered tx related. Conclusions: The combination of spartalizumab + dabrafenib + trametinib resulted in high ORR and CR rates, with a high frequency of durable responses, including in patients with poor prognostic factors. Clinical trial information: NCT02967692.

Single-center phase I/Ib study of concurrent intrathecal (IT) and intravenous (IV) nivolumab (N) for metastatic melanoma (MM) patients (pts) with leptomeningeal disease (LMD)

10008

Background: MM pts with LMD have a dismal prognosis, with a median overall survival (OS) < 3 months and no approved therapies. IT administration of interleukin-2 (IL2) achieves survival in ~15% of MM LMD pts, but at cost of severe toxicities. Given the favorable clinical activity and safety of systemic anti-PD1, we hypothesized that IT N administration is safe and can achieve clinical benefit in pts with LMD. Methods: The primary objectives of this first-in-human study (NCT03025256) were to determine the safety and the maximum tolerated dose (MTD) of IT N given with IV N in MM pts with LMD. Eligible pts had MM, ECOG PS < / = 2, and evidence of LMD by MRI and/or CSF cytology. Dexamethasone < / = 4mg/daily was allowed. For cycle 1, IT N is administered via intraventricular reservoir on day (D) 1; Blood and CSF is collected at multiple time points for translational research. For subsequent cycles (every 14 days), pts receive IT N on D1, followed by IV N 240 mg on D2. IT N doses evaluated were 5, 10, and 20 mg. Bayesian mTPI methodology was used to define the MTD. The study was recently amended to allow for concurrent BRAF/MEK inhibitor(i) treatment. Results: To date, 15 pts have been treated: two at 5, three at 10, and 10 at 20 mg IT N. Median age at LMD diagnosis was 41.8 (30.9-73.2) years; 6 pts are male. All pts had radiographic evidence of LMD and neurological symptoms; 8 pts had positive CSF cytology. 12 pts received prior therapies for their MM: anti-PD1 (n = 11), BRAFi/MEKi (n = 9), chemo (n = 2), IT IL2 (n = 4) other (n = 2). 11 pts had prior XRT, including whole brain RT (n = 7). 1 pt was treatment-naïve. The median numbers of IT N doses was 4 (1-42). No grade (Gr) 4-5 AEs were attributed to IT N or IV N; only 4 events (Gr 1, n = 2; Gr2, n = 2) were possibly related to the IT N. With a median follow-up of 18.7 weeks (1-83.3 wks), the median OS is 46.1 weeks (0.1-83.3). Clinical response data, translational research endpoints, including changes in CSF cytokines and cfDNA, will be reported. Conclusions: The trial demonstrates the feasibility of prospective clinical trials in MM patients with LMD. The combination of IT/ IV N was safe and well-tolerated, with no unexpected systemic or neurological toxicity. Final presentation will include results of LMD composite response assessment, comparative analysis of longitudinal CSF/blood samples to assess immunologic effects. Finally, the interim OS of the patients is encouraging, and supports further evaluation of IT administration of immunotherapy agents for pts with MM and LMD. Clinical trial information: NCT03025256.

Tumor microenvironment (TME), longitudinal biomarker changes, and clinical outcome in patients (pts) with advanced BRAF V600–mutant melanoma treated with first-line spartalizumab (S) + dabrafenib (D) + trametinib (T)

39

Background: Although pts with both low tumor mutation burden (TMB) and T-cell–inflamed gene expression profiles (TI-GEPs) usually have poor outcomes with anti–PD-1 therapy, an analysis in the adjuvant melanoma setting suggested that these pts benefited from adjuvant D+T therapy. Here we analyze TMB/TI-GEPs and other biomarkers in pts receiving a combination of anti–PD-1 and D+T therapy. Methods: The phase 3 COMBI-i study (NCT02967692) is evaluating S in combination with D+T in previously untreated pts with BRAF V600–mutant unresectable/metastatic melanoma. In the safety run-in (part [p] 1) and biomarker (p2) cohorts, blood/tissue samples were collected at baseline (BL), after 2-3 and 8-12 wk of treatment, and at disease progression. TMB/circulating tumor DNA (ctDNA) and TI-GEPs were examined by targeted DNA-seq and RNA-seq, respectively. Results: At data cutoff, 6 of 22 pts with DNA- and RNA-seq data available had a PFS event. At BL, these pts had low TMB, low TI-GEPs (4 of 6), or high levels of immunosuppressive TME signatures (eg, fibroblast, M2 macrophages) vs pts without a PFS event. Elevated BL ctDNA was significantly associated with PFS events ( P< .001). Pts with a complete response (CR) on S+D+T had significantly lower levels of BL immunosuppressive TME signatures (eg, M2 macrophages; P< .01) than pts without a CR. We observed a consistent increase in TI-GEPs and decrease in MAPK pathway activity score (MPAS) from BL to biopsy at 2-3 wk in all pts regardless of subsequent progression. Pts with a PFS event and available longitudinal biomarker data were characterized by a subsequent decrease in TI-GEPs and an increase in MPAS per the 8- to 12- wk biopsy sample. Conclusions: These results suggest that S+D+T had an early impact on tumor cells and the TME, potentially promoting antitumor activity. The majority of PFS events occurred in the TMB-low/TI-GEP-low subgroup. An immunosuppressive TME might preclude early CRs. The predictive implications of coupling TMB/GEP subgroups with other TME marker subgroups need further validation. The randomized placebo-controlled p3 of COMBI-i is ongoing. Clinical trial information: NCT02967692.

The anti–PD-1 antibody spartalizumab (S) in combination with dabrafenib (D) and trametinib (T) in previously untreated patients (pts) with advanced BRAF V600–mutant melanoma: Updated efficacy and safety from parts 1 and 2 of COMBI-I

57

Background: Checkpoint inhibitors and targeted therapies have improved outcomes in pts with BRAF V600–mutant advanced melanoma; however, many pts progress and new treatment (tx) strategies are needed. BRAF inhibition increases T-cell infiltration, melanoma antigen expression, and PD-1/PD-L1 expression, which may lead to synergistic activity with anti–PD-1 therapy. Methods: COMBI-i is investigating first-line S 400 mg Q4W + D 150 mg BID + T 2 mg QD in pts with unresectable or metastatic BRAF V600–mutant melanoma (NCT02967692). Here we report pooled efficacy and safety data from parts 1 (run-in cohort) and 2 (biomarker cohort). Response was assessed per RECIST v1.1. Results: 36 pts were enrolled (part 1: n = 9; part 2: n = 27); 18 (50%) had stage IV M1c and 15 (42%) had elevated LDH levels. At the data cutoff (median follow-up, 15.2 mo), tx was ongoing in 17 pts (47%). The confirmed objective response rate (ORR) by investigator assessment was 75% (n = 27), with 33% complete responses (CRs; n = 12). Medians for duration of response (DOR; 7/27 pts with events), progression-free survival (PFS; 13/36 pts with events), and overall survival (OS; 7/36 pts with events) were not reached. 12-mo DOR rate was 71.4% (95% CI, 49%-85%). 12-mo PFS and OS rates were 65.3% (95% CI, 47%-79%) and 85.9% (95% CI, 69%-94%), respectively. In pts with high baseline LDH: ORR was 67%, with 3 CRs (20%), median PFS was 10.7 mo (events in 10/15 pts [67%]), and median OS was not reached, with events in 6/15 pts (40%). All pts had ≥ 1 AE; 27 (75%) had grade ≥ 3 AEs. 6 pts (17%) had AEs leading to discontinuation of all 3 study drugs. Any-grade AEs in ≥ 40% of pts included pyrexia, chills, fatigue, cough, and arthralgia. Grade ≥ 3 AEs in > 3 pts were neutropenia, pyrexia, and increased lipase. One pt died of cardiac arrest that was not considered related to study tx. Conclusions: S+D+T showed promising and durable ORR (75%) with CR in 33% of pts. With > 15 mo of follow-up, median PFS was not reached. The safety profile was manageable reflecting individual toxicities of D, T, and S. The global, placebo-controlled, randomized phase 3 (part 3) of COMBI-i is ongoing. Clinical trial information: NCT02967692.

Incidence, patterns of progression, and outcomes of preexisting and newly discovered brain metastases during treatment with anti-PD-1 in patients with metastatic melanoma

BACKGROUND

Melanoma brain metastases (MBM) occur in up to 50% of patients with metastatic melanoma (MM) and represent a frequent site of systemic treatment failure for targeted therapies. However, to the authors' knowledge, little is known regarding the incidence, patterns of disease progression, and outcomes of MBM in patients treated with anti-PD-1 immunotherapy.

METHODS

A total of 320 patients with MM who were treated with anti-PD-1 at The University of Texas MD Anderson Cancer Center in Houston were reviewed. Analyses were performed to identify factors associated with brain metastasis-free survival and overall survival (OS) using Cox regression models.

RESULTS

The median age of the patients was 63.3 years. OS from the initiation of anti-PD-1 therapy was not significantly different between patients without MBM prior to anti-PD-1 compared with patients with prior MBM (P = .359). Among patients without prior MBM, 21 patients (8.6%) developed MBM during anti-PD-1 therapy, 12 of whom (4.9%) presented with disease progression in the central nervous system (CNS) only. Developing MBM during or after therapy with anti-PD-1 (hazard ratio, 4.70; 95% CI, 3.18-6.93) was associated with shorter OS. Among patients with MBM prior to anti-PD-1 treatment, 15 (20.0%) progressed in the CNS only and 19 (25.3%) progressed both intracranially and extracranially; at the time of the last data cutoff, 27 patients (36.0%) had not developed disease progression. Radiation necrosis occurred in 11.3% of patients (7 of 62 patients) in the group with a prior MBM who received stereotactic radiosurgery.

CONCLUSIONS

Anti-PD-1 therapy may change the natural history of patients with preexisting MBM. However, CNS failure during treatment with anti-PD-1 is predictive of a worse prognosis compared with extracranial progression. The results of the current study support the activity of anti-PD-1 in patients with MBM, although routine CNS imaging during therapy is warranted.

Efficacy and safety of the combination of nivolumab (NIVO) plus ipilimumab (IPI) in patients with symptomatic melanoma brain metastases (CheckMate 204)

9501

Background: We previously reported efficacy and safety of NIVO+IPI in patients (pts) with untreated, asymptomatic, melanoma brain metastases (MBM) from the CheckMate 204 study. Here, we provide the first report of NIVO+IPI in pts with symptomatic MBM, and report updated data in pts with asymptomatic MBM. Methods: In this phase II trial, pts with ≥1 measurable, nonirradiated MBM 0.5–3.0 cm were enrolled into two cohorts: (1) those with no neurologic symptoms or steroid Rx (asymptomatic; cohort A); and (2) those with neurologic symptoms, whether or not they were receiving steroid Rx (symptomatic; cohort B). In both cohorts, pts received NIVO 1 mg/kg + IPI 3 mg/kg Q3W × 4, then NIVO 3 mg/kg Q2W until progression or toxicity. The primary endpoint was intracranial clinical benefit rate (CBR; proportion of pts with complete response [CR] + partial response [PR] + stable disease [SD] ≥6 mo). As of the clinical cutoff date on May 1, 2018, all treated pts (101 in cohort A and 18 in cohort B) had been followed for ~6 mo or longer. Results: In this updated analysis of cohort A (median follow-up of 20.6 mo), the CBR was 58.4% (Table). In cohort B, pts received a median of 1 NIVO+IPI dose and 2 of 18 pts (11%) received all 4 doses. At a median follow-up of 5.2 months in cohort B, intracranial objective response rate was 16.7% and the CBR was 22.2%. Grade 3/4 adverse events occurred in 54.5% of pts in cohort A and in 55.6% of pts in cohort B (6.9% and 16.7% in the nervous system, respectively), with one death related to treatment in cohort A (immune-related myocarditis). Conclusions: In pts with asymptomatic MBM, our updated results show a high rate of durable intracranial responses, further supporting NIVO+IPI as a first-line treatment in this population. Intracranial antitumor activity was observed with NIVO+IPI in pts with symptomatic MBM, but further study is needed to understand the biologic mechanisms of resistance to immunotherapy and to improve treatments in this challenging population. Clinical trial information: NCT02320058. [Table: see text]

Lymphodepletion (LD), tumor-infiltrating lymphocytes (TIL) and high (HD-IL2) versus low-dose (LD-IL2) IL-2 followed by pembrolizumab (pembro) in patients (pts) with metastatic melanoma (MM)

9543

Background: TIL adoptive cell transfer (ACT) therapy can produce durable responses for MM pts although efficacy appears lower in the era of checkpoint inhibitors. Toxicities from HD-IL2, including sepsis physiology, limits widespread use of this regimen. Suppression of transferred TIL by either tumor cells or the tumor microenvironment could limit TIL responses. Pembro is known to promote T cell activation, thus, we evaluated the efficacy and safety of TIL with pembro with HD-IL2 versus LD-IL2. Methods: Pts with MM who had tumor harvested and cryopreserved TIL at MD Anderson with PS 0-1 and normal organ function were eligible. All pts received a standard LD regimen consisting of cyclophosphamide and fludarabine, followed by infusion of pooled ex-vivo expanded TIL and either HD-IL2 (Arm 1: 720,000 IU/kg IV q 8 hrs up to 15 doses) or LD-IL2 (Arm 2: 2 million IU SC for 14 d). Pts received pembro 200mg IV starting 21 d post T cell infusion every 3 wks for up to 2 yrs. Pts were randomized 1:1 based on stage and LDH. Paired blood and tumor biopsies were obtained prior to LD, prior to first and second dose of pembro and at time of progression. Results: A total of 36 pts were planned to enroll (18 in each arm); however, the protocol met pre-specified futility boundaries in Arm 1 which prompted early closure after treatment of 14 pts (7 in each Arm). Median age was 50 yrs, 6 were female, 8 had cutaneous melanoma, 2 mucosal, 2 uveal and 2 unknown primary. 86% were stage M1c, 14% M1D, 50% had LDH elevation. Median lines of prior therapy were 3 (range 1-6), including prior anti PD-1 in 13 pts. Best overall response was 1 PR (for 10 mos), 2 SD, 3 PD, 1 NE in Arm 1; 1 PR (ongoing over 36 mos), 1 SD, 5 PD in Arm 2. With median follow up of 9.2 mos, PFS was 3.9 mos for Arm 1 and 2.1 mos for Arm 2 (p = 0.99). Median OS was 9.7 mos for Arm 1 and 8.8 mos for Arm 2 (p = 0.71). Toxicity was similar in both Arms but with lower rates of grade 3 febrile neutropenia (57% vs. 71%) and shorter hospital stay (median 16 vs. 18 d) in Arm 2 vs. Arm 1. Conclusions: In a heavily treated pt population, TIL with pembro achieved low response rates. Use of LD-IL2 did not diminish efficacy and may be better tolerated than HD-IL2 for TIL ACT. Correlative studies are ongoing to determine mechanisms of treatment response and failure. Clinical trial information: NCT02500576.

The anti–PD-1 antibody spartalizumab (S) in combination with dabrafenib (D) and trametinib (T) in previously untreated patients (pts) with advanced BRAF V600–mutant melanoma: Updated efficacy and safety from parts 1 and 2 of COMBI-i

9531

Background: Checkpoint inhibitors and targeted therapies have improved outcomes in pts with BRAF V600–mutant advanced melanoma; however, many pts progress and new treatment (tx) strategies are needed. BRAF inhibition increases T-cell infiltration, melanoma antigen expression, and PD-1/PD-L1 expression, which may lead to synergistic activity with anti–PD-1 therapy. Methods: COMBI-i is investigating first-line S 400 mg Q4W + D 150 mg BID + T 2 mg QD in pts with unresectable or metastatic BRAF V600–mutant melanoma (NCT02967692). Here we report pooled efficacy and safety data from parts 1 (run-in cohort) and 2 (biomarker cohort). Response was assessed per RECIST v1.1. Results: 36 pts were enrolled (part 1: n = 9; part 2: n = 27); 18 (50%) had stage IV M1c and 15 (42%) had elevated LDH levels. At the data cutoff (median follow-up, 15.2 mo), tx was ongoing in 17 pts (47%). The confirmed objective response rate (ORR) by investigator assessment was 75% (n = 27), with 33% complete responses (CRs; n = 12). Medians for duration of response (DOR; 7/27 pts with events), progression-free survival (PFS; 13/36 pts with events), and overall survival (OS; 7/36 pts with events) were not reached. 12-mo DOR rate was 71.4% (95% CI, 49%-85%). 12-mo PFS and OS rates were 65.3% (95% CI, 47%-79%) and 85.9% (95% CI, 69%-94%), respectively. In pts with high baseline LDH: ORR was 67%, with 3 CRs (20%), median PFS was 10.7 mo (events in 10/15 pts [67%]), and median OS was not reached, with events in 6/15 pts (40%). All pts had ≥ 1 AE; 27 (75%) had grade ≥ 3 AEs. 6 pts (17%) had AEs leading to discontinuation of all 3 study drugs. Any-grade AEs in ≥ 40% of pts included pyrexia, chills, fatigue, cough, and arthralgia. Grade ≥ 3 AEs in > 3 pts were neutropenia, pyrexia, and increased lipase. One pt died of cardiac arrest that was not considered related to study tx. Conclusions: S+D+T showed promising and durable ORR (75%) with CR in 33% of pts. With > 15 mo of follow-up, median PFS was not reached. The safety profile was manageable reflecting individual toxicities of D, T, and S. The global, placebo-controlled, randomized phase 3 (part 3) of COMBI-i is ongoing. Clinical trial information: NCT02967692.

Clinical activity of pembrolizumab (P) in undifferentiated pleomorphic sarcoma (UPS) and dedifferentiated/pleomorphic liposarcoma (LPS): Final results of SARC028 expansion cohorts

11015

Background: Immune checkpoint inhibitors have demonstrated activity in multiple tumor types but their activity in soft tissue sarcomas remains limited. In the multicenter phase II study, SARC028, the anti-PD-1 antibody, P demonstrated objective responses that were largely restricted to UPS and LPS subtypes. We now report outcomes from 2 expansion cohorts of SARC 028 in advanced UPS and LPS. Methods: To further confirm the clinical activity of P in UPS and LPS, we enrolled an additional 30 pts in each of 2 expansion cohorts for a total of 40 UPS and 40 LPS pts. Primary endpoint was investigator-assessed response by RECIST v1.1. Secondary endpoints were safety, progression-free survival (PFS), 12-week PFS rate, and overall survival (OS). An ORR of 25% was considered clinically meaningful and < 10% was considered to show lack of efficacy. P was to be considered a success if 8 or more of 40 enrolled patients had a PR or better (1-sided α = 0.042, 82% power). Pts age ≥18 with advanced, refractory UPS or LPS received 200 mg of P IV every 3 weeks until progression or unacceptable toxicity. Results: Preliminary results from the first 10 pts in each of the UPS and LPS cohorts have been reported. We now present summary data after enrolling an additional 30 pts in each cohort. The ORR in the UPS cohort was 23% (9/40), with an additional 5/30 PRs observed in the expansion cohort (total 2 CRs, 7 PRs). In the LPS cohort, the ORR was 10% (4/39 evaluable pts), with an additional 2/30 PRs observed (total 4 PRs). Median PFS for the UPS group was 3 months [95% CI: 2, 5] and 2 months [95% CI: 2, 4] for the LPS group. 12-week PFS rate was 50% in UPS [95% CI: 35, 65] and 44% in LPS [95% CI: 28, 60]. The UPS group had a median OS of 12 months [95% CI: 7, 34] and 13 months [95% CI: 8, NR] for the LPS group. P was well tolerated with no unexpected toxicities. Conclusions: The UPS cohort achieved its primary endpoint, however the activity of P in UPS deserves further evaluation in a randomized study. The activity of P was not confirmed in the LPS cohort. Ongoing biomarker analyses may direct better patient selection and guide future combination strategies. Clinical trial information: NCT02301039.

Tumor microenvironment (TME), longitudinal biomarker changes, and clinical outcome in patients (pts) with advanced BRAF V600–mutant melanoma treated with first-line spartalizumab (S) + dabrafenib (D) + trametinib (T)

9515

Background: Although pts with both low tumor mutation burden (TMB) and T-cell–inflamed gene expression profiles (TI-GEPs) usually have poor outcomes with anti–PD-1 therapy, an analysis in the adjuvant melanoma setting suggested that these pts benefited from adjuvant D+T therapy. Here we analyze TMB/TI-GEPs and other biomarkers in pts receiving a combination of anti–PD-1 and D+T therapy. Methods: The phase 3 COMBI-i study (NCT02967692) is evaluating S in combination with D+T in previously untreated pts with BRAF V600–mutant unresectable/metastatic melanoma. In the safety run-in (part [p] 1) and biomarker (p2) cohorts, blood/tissue samples were collected at baseline (BL), after 2-3 and 8-12 wk of treatment, and at disease progression. TMB/circulating tumor DNA (ctDNA) and TI-GEPs were examined by targeted DNA-seq and RNA-seq, respectively. Results: At data cutoff, 6 of 22 pts with DNA- and RNA-seq data available had a PFS event. At BL, these pts had low TMB, low TI-GEPs (4 of 6), or high levels of immunosuppressive TME signatures (eg, fibroblast, M2 macrophages) vs pts without a PFS event. Elevated BL ctDNA was significantly associated with PFS events ( P< .001). Pts with a complete response (CR) on S+D+T had significantly lower levels of BL immunosuppressive TME signatures (eg, M2 macrophages; P< .01) than pts without a CR. We observed a consistent increase in TI-GEPs and decrease in MAPK pathway activity score (MPAS) from BL to biopsy at 2-3 wk in all pts regardless of subsequent progression. Pts with a PFS event and available longitudinal biomarker data were characterized by a subsequent decrease in TI-GEPs and an increase in MPAS per the 8- to 12- wk biopsy sample. Conclusions: These results suggest that S+D+T had an early impact on tumor cells and the TME, potentially promoting antitumor activity. The majority of PFS events occurred in the TMB-low/TI-GEP-low subgroup. An immunosuppressive TME might preclude early CRs. The predictive implications of coupling TMB/GEP subgroups with other TME marker subgroups need further validation. The randomized placebo-controlled p3 of COMBI-i is ongoing. Clinical trial information: NCT02967692.

Pathological response and survival with neoadjuvant therapy in melanoma: A pooled analysis from the International Neoadjuvant Melanoma Consortium (INMC)

9503

Background: Pathological complete response (pCR) to neoadjuvant systemic therapy (NST) correlates with survival, and is recognized as a path to regulatory approval in several cancers. Recent trials have reported that neoadjuvant immunotherapy (IT) and targeted therapy (TT) regimens achieve high pCR rates and impressive recurrence-free survival in stage III melanoma, however, the relationship between pCR, relapse-free (RFS) and overall survival (OS) in larger datasets of melanoma patients (pts) remains unknown. Methods: We pooled data from 6 modern NST clinical trials of anti-PD-1 based immunotherapy or BRAF/MEK targeted therapy conducted across institutions participating in the INMC. Pts with RECIST measurable, surgically resectable clinical stage III melanoma who underwent surgery were included. NST regimens included nivolumab (as monotherapy or in combination with ipilimumab), pembrolizumab or dabrafenib+trametinib. Baseline disease characteristics, treatment regimen, pCR and RFS were examined. Results: 184 pts with clinical stage III melanoma (AJCCv7: 100 IIIB, 84 IIIC) completed NST (133 IT, 51 TT) and underwent surgery. Median age was 57y (range 18-87). A pCR was observed in 41% of patients; 51 (38%) with IT and 24 (47%) with TT. Median follow-up post-surgery is 13 mo (95% CI 12-16); 10 mo with IT and 22 mo with TT. 44 (24%) pts have recurred (17 loco-regional, 21 distant, 6 both sites at first recurrence), 18 (14%) after IT and 26 (51%) after TT. 12-month RFS was improved with IT vs TT (83% vs 65%, p < 0.001). For those with pCR, 7% have recurred, 0/51 (0%) after IT, 7/17 (41%) after TT. For those without pCR, 34% have recurred, 18/82 (22%) after IT and 19/27 (70%) after TT. 12-month RFS was improved in those with pCR vs without pCR (95% vs 62%, p < 0.001), including in those with IT (100% vs 72%, p < 0.001) and TT (88% vs 43%, p < 0.001). 16 (9%) patients have died including two who had a pCR, both from TT. Conclusions: Neoadjuvant IT and TT are active regimens in resectable clinical stage III melanoma patients and are associated with high pCR rate. The ability to achieve pCR correlates with improved RFS and remarkably no patient with pCR from immunotherapy has recurred to date.

A phase II study of oral azacitidine (CC-486) in combination with pembrolizumab (PEMBRO) in patients (pts) with metastatic melanoma (MM)

9560

Background: Immune checkpoint blockade (ICB) have improved survival for many pts with MM, offering durable responses in up to 35% of pts, but many have short-lived or no response ( > 40%). A potential immune escape mechanism is the subversion of cellular epigenetic machinery to impact multiple aspects of the immune response such as suppression of Cancer Testis Antigen (CTA), which can be reversed in preclinical models by DNA hypomethylating agents (HMA), thereby increasing cancer cell immunogenicity. HMAs can also increase T cell infiltration and T cell-mediated tumor killing, and they achieve synergy with CBI in preclinical models. This suggests that epigenetic therapy with CBI is a rational combination to target MM. We hypothesize that CC-486 (an oral HMA) + PEMBRO will be tolerated at biologically relevant doses and enhance response to PEMBRO in pts with MM who are PD-1 naïve and reverse resistance to (ICB) in pts refractory/resistant to PD-1. Methods: This study (NCT02816021) evaluated the safety and efficacy of CC-486 (300 mg PO QD on days 1-14/21 day cycle) + PEMBRO (200mg IV Q 21 days) defined by Objective Response Rate (ORR) by RECIST 1.1 in pts with MM. PD-1 naïve pts were assigned to Arm A and pts with progression on prior PD-1 therapy to Arm B. Unlimited prior systemic therapies were allowed on Arm B. Continuous monitoring for toxicity and futility was performed and assumes an ORR of > 35% (Arm A) and > 15% (Arm B) at 95% power. Tumor biopsies at baseline and post treatment were mandated. Results: 22pts, 11 in each arm, have been treated. The most common AEs were nausea, vomiting, diarrhea, fatigue, and anemia. The most common gr 3/4 toxicities were neutropenia (3), diarrhea (2), dehydration (2), and rectal hemorrhage (1). 5 of 9 evaluable pts in Arm A achieved a PR (55% ORR); 0 of 9 evaluable pts in Arm B pts have responded. Conclusions: Although this regimen was tolerated in both arms, Arm B met futility stopping rules and was closed. The initial response rate in Aim A (55%) is promising, and accrual to this Arm continues. Analyses of longitudinally collected tumor biopsies are underway to interrogate the effects of HMA on the immune response to both arms. Clinical trial information: NCT02816021.

Real-world outcomes with immuno-oncology (IO) therapies: A prospective, observational cohort study in patients (pts) with advanced melanoma (OPTIMIzE)

e14144

Background: There is little real-world evidence evaluating treatment patterns and outcomes with IO therapies for pts with advanced melanoma (aMEL). We present results from the OPTIMIzE (NCT02780089) study in pts with aMEL receiving IO therapies. Methods: OPTIMIzE is a US-based multisite (150 sites), community-based study of adult pts with aMEL. Pts receiving first-line (1L) nivolumab (NIVO)+ipilimumab (IPI), anti-PD-1 (NIVO/pembrolizumab), or IPI between 2011-2018 with a minimum 1 y of follow-up were included. Baseline characteristics, objective response rate (ORR), overall survival (OS), treatment-related adverse events (TRAEs), and quality of life (QoL) were analyzed. QoL assessments included the Functional Assessment of Cancer Therapy–Melanoma (FACT-M), EQ-5D index, and visual analog scale (VAS). Results: Cohort size: 81 NIVO+IPI, 147 anti-PD-1, and 16 IPI (IPI arm not included in the analysis). Overall, mean age was 64.5 y; 42% had BRAF mutation. Mean follow-up was 14.1 mo. Pts in the NIVO+IPI group were younger, had better ECOG performance status, and a higher likelihood of M1c disease and elevated LDH vs the anti-PD-1 group. ORR was higher for pts treated with NIVO+IPI vs anti-PD-1 (48% vs 33%, P= 0.08). Unadjusted 1-y OS was 78.4% for NIVO+IPI and 73.1% for anti-PD-1. In multivariate Cox model analysis, the hazard ratio for OS for NIVO+IPI vs anti-PD-1 was 0.78 (95% CI, 0.46–1.33; P= 0.36). Grade 3/4 TRAEs occurred in 53% and 22% of pts in the NIVO+IPI and anti-PD-1 groups, respectively ( P˂0.001). QoL changes from baseline were clinically meaningful for EQ-5D VAS and FACT-M in the NIVO+IPI group at 12 mo (Table). After adjusting for baseline covariates, the difference at 12 mo between NIVO+IPI vs anti-PD-1 was 6.7 ( P= 0.04) for EQ-5D VAS and 8.8 ( P= 0.02) for FACT-M. Conclusions: Safety and efficacy outcomes from this prospective real-world study are consistent with those reported in prior clinical trials in treatment-naive aMEL pts. No clinically meaningful deterioration in QoL measures was observed in either group. Clinical trial information: NCT02780089. [Table: see text]

Stool donor qualification and collection from metastatic melanoma (MM) patients (pts) who have responded to checkpoint inhibitors (CPI) for manufacturing of fecal microbiota transplantation (FMT)

TPS146

Background: There have been remarkable improvements in responses rates (RR) and outcomes for pts with MM with the use of single agent CPIs. However, only 35% of pts respond to therapy and less than 10% achieve a complete response (CR). Although CPIs are approved for advanced MM treatment, there is a critical need to identify predictors of response and improve outcomes for these pts, the majority of whom will die from their disease. In an analysis of stool from MM pts prior to receiving CPI (anti-PD1), MD Anderson reported the association of higher alpha diversity and a favorable “Type I” signature with improved RR and prolonged PFS. Subsequently, FMT in mice via oral gavage using stool from CR MM pts responding to anti-PD1 with a favorable microbiome signature and treated with CPI demonstrated improved RR compared to FMT with stool from non-responders. Although FMT has been studied and has shown efficacy in other diseases, clinical safety and utility in pts with MM requires investigation. We hypothesize that FMT from MM pts with CR to CPIs and a Type I signature will be tolerable and demonstrate favorable outcomes. Methods: To initiate the testing of this hypothesis, we designed a study to identify and screen pts with MM who have responded to anti-PD1 for FMT stool donation. Pts must be in CR from MM for 6 months on 2 consecutive scans. Screening procedures per standard practice of approved INDs for FMT include health history questionnaires, physical exam, confirmation of current disease status, infectious disease screening, and an evaluation of the stool sample to ensure Type I signature requirements. Notably, there have been specific modifications made to this protocol in donor eligibility criteria, as accepted by the FDA, to accommodate this unique patient population. Participants will donate stool for up to 4 weeks and may be considered for subsequent donation cycles after undergoing re-screening. Stool will be manufactured into capsule form and used in the clinical trial. This study is open and active at three sites, MD Anderson, MGH, and DFCI.

Prognostic factors for overall survival (OS) in metastatic melanoma (MM) patients (pts) treated with immune checkpoint inhibitors: A single institution study of 696 pts

9574

Background: Limited OS data, including prognostic and predictive factors of response, is available in mm pts treated with immune checkpoint inhibitors. Methods: A single-institution retrospective review was conducted on 696 mm pts treated with single-agent anti CTLA-4 or anti PD-1 on and off clinical trial between 2011-2015. Median OS was calculated from mm diagnosis. Results:Median age at mm diagnosis was 60 years old (range 15-86) and 65.2% were male. Subtypes were 63.2% non-acral cutaneous, 17.2% unknown primary, 7.8% mucosal, 6.5% acral, and 5.3% uveal. AJCC v7 staging at diagnosis was 7.9% M1a, 16.5% M1b, 33.0% M1c, and 42.5% not staged due to unknown LDH. LDH was elevated in 18.0% (400 pts). Mutation rates were 30.0% BRAF V600E/K (636 pts tested) and 24.5% NRAS (429 pts tested). First-line therapy for BRAF V600E/K mm pts included anti CTLA-4 (24.1%), BRAF/MEK targeted therapy (21.5%) and anti PD-1 (8.9%). First-line therapy for BRAF WT mm pts included anti CTLA-4 (28.1%) and anti PD-1 (12.8%). Median OS from mm for the cohort was 36.5 months (95% CI 33.3-44.9). Elevated LDH and staging correlated with OS (p < 0.001, p < 0.001, respectively) on univariate analysis. Age, gender, subtype and mutation status were not significantly associated with OS. Compared to BRAF WT, pts with BRAF V600E/K mutation were younger (median = 53 vs 62 yrs, p < 0.001), more likely to have non-acral cutaneous mm (83.2% vs 58.0%, p < 0.001) and have a diagnosis of brain metastasis during the disease course (57.0% vs 28.8%, p < 0.001). While adjusting for stage, there was no significant difference in OS based on first or second line therapy in pts with BRAF V600E/K mm or first line therapy in BRAF WT MM; however, BRAF WT pts treated second line with anti-PD1 were observed to have improved OS compared with pts receiving anti-CTLA 4 (HR 0.43 95% CI:0.23-0.84 p = 0.012). Conclusions: This study demonstrates that LDH and stage are prognostic of OS in all mm pts treated with single agent immune therapy. Second line therapy in BRAF WT pts treated with single agent immune therapy is also prognostic of OS thus prompting further investigation to determine advantageous therapy sequencing in MM.

Multicenter phase II study of pembrolizumab (P) in advanced soft tissue (STS) and bone sarcomas (BS): Final results of SARC028 and biomarker analyses

11008

Background: SARC028 is the first multicenter Phase II study of P monotherapy in patients (pts) with STS and BS. Designed to detect clinical efficacy signals in multiple histologies, the study collected blood & tissue samples on all pts. We report extended clinical follow-up and in-depth biomarker correlates of response. Methods: The primary endpoint was objective response rate (ORR) by RECIST 1.1. Secondary endpoints were safety, 12 wk progression-free survival (PFS), and overall survival (OS). The STS arm had 10 pts in each of 4 cohorts: undifferentiated pleomorphic sarcoma (UPS), dedifferentiated liposarcoma (DDLPS), synovial sarcoma (SS) and leiomyosarcoma (LMS). The BS arm included 40 pts with osteosarcoma (OS), Ewing sarcoma (ES) or dedifferentiated chondrosarcoma (CS). Pre- and on-P biopsies were required as well as blood at multiple time points. Tumor was assessed for PD-L1 expression (clone 22C3) and immune infiltrates by multi-color IHC (Vectra). Ongoing analyses include circulating cytokine and checkpoint levels and exome (DNA), transcriptome (RNA), and T-cell receptor (TCR) sequencing. Results: 86 pts were enrolled, 80 were evaluable for response. For STS, median follow-up was 14.5 months. The ORR in the overall STS cohort was 18% and the 12-wk PFS 55% [95% CI, 42-71]). Clinical activity was variable by histologic subtype with 40% ORR in UPS (1 CR and 3PR out of 10 evaluable pts), 2 PR/10 were seen in DDLPS, 1PR/10 in SS and 0/10 in LMS. For BS, median follow-up was 12.3 months (ORR 5%; 12-wk PFS 28% [95% CI, 14-41]), with 1PR/22 OS, 1PR/5 CS and 0/13 ES. 70 pre-P tissues were analyzed (11 excluded for insufficiency), with PD-L1+ in 3/70 (4%); all 3 were UPS. Of the 2 evaluable pts, 1 had CR and 1 PR. 2 OS were PD-L1+ on multi-color IHC, 1 had PR. All PD-L1+ samples had CD8+ T-cell infiltration. There were no post-P PD-L1+ samples. Conclusions: P has clinical activity in UPS and LPS, and expansion cohorts in those subtypes are planned. Pre-treatment PD-L1 expression was infrequent, but correlated with T-cell infiltration and response in UPS & OS. Ongoing biomarker analyses that may guide combination strategies are ongoing and will be presented at the meeting. Clinical trial information: NCT02301039.

Incidence, patterns of progression and outcomes of melanoma brain metastasis (MBM) during programmed-death 1 inhibitor (PD1i) therapy

9532

Background: MBM are common in patients (pts) with metastatic melanoma (MM) and represent a frequent site of treatment failure with current therapies. Little is known, however, about the incidence, patterns of progression and outcomes of MBM pts treated with PD1i and in conjunction with central nervous system (CNS) focused therapy. Methods: Outcomes of mm pts treated with PD1i at MD Anderson from 01/12 to 07/16 were reviewed. The association between clinical variables and development of MBM and overall survival (OS) were assessed using logistic regression and Cox regression analyses. Results: We identified 324 mm pts, including 77 pts (24%) who had MBM prior to first dose of PD1i. Median follow-up from start of therapy was 16.3 months, median OS for pts without MBM at the start of PD1i 3.37 years, as compared to 2.85 years in pts with prior MBM (p = 0.268). Of the 247 pts without prior MBM, 64 (26%) developed MBM after exposure to PD1i. Of those, 21 pts (8.5%) developed MBM during therapy or within 30 days of discontinuation, with 12 (4.5%) having CNS-only progression, while 9 (3.6%) had both systemic and CNS progression. Pts with MBM prior to PD1i (n = 77) had CNS-only progression in 22 pts (28.6%) during therapy. Progression occurred in systemic and systemic plus CNS in 12 pts (15.6%) and 19 pts (24.7%), respectively. 24 pts (31.2%) had stable disease (SD). On multivariate analysis, pts with lung metastases (OR, 2.16; 95% CI, 1.25 - 3.78; p = 0.006) and NRAS-mutated tumors (OR, 2.17; 95% CI, 1.14 - 4.18; p = 0.02) were more likely to develop MBM; pts who had liver metastases at the start of PD1i (HR, 1.77; 95% CI, 1.09 - 2.87; p = 0.002) and those who developed MBM during PD1i (HR, 4.81; 95% CI, 3.00 - 7.71; p < 0.0001) had increased risk of death. Conclusions: We found a 26% incidence of MBM after PD1i exposure. Pts that develop MBM are still at higher risk of death despite advances in systemic and local CNS therapy. CNS-only progression was substantially higher in patients with MBM prior to PD1i, supporting a change in the natural history of the disease after PD1i. These findings support the use of CNS imaging to monitor disease during PD1i therapy.

Relapse-free survial and target identification to enhance response with neoadjuvant and adjuvant dabrafenib + trametinib (D+T) treatment compared to standard-of-care (SOC) surgery in patients (pts) with high-risk resectable BRAF-mutant metastatic melanoma

9587

Background: Targeted and immune therapies have dramatically improved outcomes in stage IV metastatic melanoma pts. These agents are now being tested in earlier-stage disease. SOC surgery for high-risk resectable melanoma (AJCC stage IIIB/IIIC), with or without adjuvant therapy, is associated with a high risk of relapse (~70%). We hypothesized that neoadjuvant (neo) + adjuvant treatment with D+T improves RFS in these pts. Longitudinally collected biospecimens from pts receiving this treatment were analyzed to identify candidate strategies to further improve outcomes. Methods: A prospective single-institution randomized clinical trial (NCT02231775) was conducted in BRAF-mutant pts with resectable Stage IIIB/C or oligometastatic stage IV melanoma. Pts were randomized 1:2 to SOC (Arm A) versus neo + adjuvant D+T (Arm B; 8 wks neo + 44 wks adjuvant). The primary endpoint was RFS. Tumor biopsies were collected at baseline, week 3, and at surgery for molecular and immune profiling (whole exome sequencing, gene expression profiling, IHC, flow cytometry). Results: 21 of a planned 84 patients were enrolled (Arm A = 7, Arm B = 14). Arms were well balanced for standard prognostic factors, and toxicity was manageable. RECIST response rate with neo D+T was 77%, and the pathologic complete response rate (pCR) was 58%. First interim analysis revealed significantly improved RFS in the D+T arm over SOC (HR 62.5, p < 0.0001), leading to early closure to enrollment. Pts with a pCR at surgery had significantly improved RFS versus pts without pCR (p = 0.04) on neo D+T. Tumor profiling revealed incomplete MAPK pathway blockade and higher levels of CD8+ T cells expressing immunomodulators Tim-3 and Lag-3 in pts who did not achieve a pCR. Conclusions: Neo + adjuvant D+T is associated with a high pCR rate and markedly improved RFS over SOC in pts with high-risk resectable BRAF-mutant metastatic melanoma. pCR at surgery is associated with improved RFS. Tumor analyses reveal candidate targets for testing in future trials to enhance responses to neo D+T. Clinical trial information: NCT02231775.

The safety and early efficacy of high-dose ipilimumab (IPI) and the combination nivolumab plus ipilimumab (NIVO + IPI) in patients (pts) with uveal melanoma (UM)

9554

Background: UM metastases occur in 50% of cases and high-risk pts are identified by a gene expression profile. High-dose IPI is approved for adjuvant (adj) treatment (tx) of cutaneous melanoma and NIVO + IPI for metastatic (met) melanoma, yet the safety and efficacy of high-dose IPI or NIVO + IPI has not been established in UM in the adj or met settings. Methods: We performed a phase I/II trial of IPI for the tx of high-risk & met UM (CA184-187). The study consisted of two arms: an adj arm (AA) & met arm (MA) with two dose levels, 3 mg/kg & 10 mg/kg. Dose-finding proceeded on each arm in a 3 + 3 fashion. Pts received IPI once every 3 weeks for four doses followed by maintenance IPI every 12 weeks (for up to one year in AA). The AA treated pts with a Class 2 gene expression profile. This score imparts a 3-year distant metastasis-free survival (DMFS) of 50%. The primary endpoint for the AA was maximum tolerated dose (MTD) and improvement in 3-year DMFS to 70%. The primary endpoint for the MA was MTD & overall survival. The study was later amended to include a cohort of UM pts treated with combination NIVO + IPI in the standard FDA approved schedule. Results: Ten pts were enrolled on AA, 18 on MA, and 20 on NIVO + IPI. Adverse events (AEs) of any Grade (Gr) related to tx occurred in 80% of pts on AA. Gr 3/4 related toxicities observed in more than one pt were: transaminitis (30%) & pruritus (20%). Of these, 10% of the elevated AST and ALT and 10% of the pruritus occurred during the dose-finding portion of the trial at 3 mg/kg. One pt developed biopsy-proven colitis, and one developed diarrhea. Both were treated with high-dose steroids. One pt developed vasculitis manifesting as temporal arteritis with resultant blindness. AEs of any Gr occurred in 44% of pts on MA. Gr 3/4 toxicities observed in more than one pt were: Fatigue (11%) and Hyperbilirubinemia (11%). Only 1 pt (5.6%) developed Gr 3/4 diarrhea, and this was at the 3 mg/kg dose. In the NIVO + IPI cohort, Gr 3 transaminitis & elevated TSH occurred in 10%. Conclusions: High-dose IPI in UM did not demonstrate new or unexpected toxicities. Similarly, the combination of NIVO + IPI was well-tolerated with no new toxicities. Efficacy data will be presented at the meeting. Clinical trial information: NCT01585194.

Efficacy and safety of nivolumab (NIVO) plus ipilimumab (IPI) in patients with melanoma (MEL) metastatic to the brain: Results of the phase II study CheckMate 204

9507

Background: Brain metastases (BMts) are a major cause of morbidity/death in MEL. We report the first efficacy data in MEL patients (pts) with BMts who received NIVO+IPI in study CheckMate 204. Methods: In this multicenter US trial (NCT02320058), MEL pts with ≥1 measurable BMt 0.5-3.0 cm and no neurologic symptoms or steroid Rx received NIVO 1 mg/kg + IPI 3 mg/kg Q3W x 4, then NIVO 3 mg/kg Q2W until progression or toxicity. Pts with severe adverse events (AEs) during NIVO+IPI could receive NIVO when toxicity resolved; stereotactic radiotherapy (SRT) was allowed for brain oligo-progression if an assessable BMt remained. The primary endpoint was intracranial (IC) clinical benefit rate (complete response [CR] + partial response [PR] + stable disease [SD] > 6 months). The planned 90-pt accrual is complete; we report efficacy and updated safety for 75 pts with disease assessment before the Nov 2016 database lock. Results: Median age was 59 yrs (range 22–79). Median number of induction doses was 3; 26 pts (35%) received 4 NIVO+IPI doses and 38 pts (51%) began NIVO maintenance. Response data are reported at a median follow-up of 6.3 months (Table). The IC objective response rate (ORR) was 56% (95% CI: 44–68); 19% of pts had a complete response. IC and extracranial responses were largely concordant. Rx-related grade 3/4 AEs occurred in 48% of pts, 8% neurologic, including headache and syncope. Only 3 pts (4%) stopped Rx for Rx-related neurologic AEs. One pt died of immune-related myocarditis. Conclusions: In CheckMate 204, prospectively designed to investigate NIVO+IPI in MEL pts with BMts, NIVO+IPI had high IC antitumor activity with objective responses in 56% of pts, CR in 19%, and no unexpected neurologic safety signals. The favorable safety and high anti-melanoma activity of NIVO+IPI may represent a new Rx paradigm for pts with asymptomatic MEL BMts and could change practice to avoid or delay whole brain RT or SRT. Clinical trial information: NCT02320058. [Table: see text]

Molecular and immune predictors of response and toxicity to combined CTLA-4 and PD-1 blockade in metastatic melanoma (MM) patients (pts)

9579

Background: Combined treatment with ipilimumab and nivolumab (Ipi/Nivo) achieves clinical responses in > 50% of mm pts. However, responses are not universal and toxicity may be limiting, thus biomarkers of response and toxicity are needed to optimize and personalize this therapy. Methods: Tumor biopsies were collected before (n = 29) and on treatment (n = 7) from mm pts (n = 40) treated with Ipi/Nivo. Whole exome sequencing (WES), gene expression profiling, TCR sequencing, and immunohistochemistry (IHC) were performed to define molecular and immune features of the tumors. Radiographic responses in patients were assessed via RECIST 1.1criteria, and patients were classified as responders (R) deriving clinical benefit (with SD, PR, CR) and non-responders (NR) not deriving clinical benefit (PD). Toxicity was also scored, with patients dichotomized into low toxicity ( < grade 2) versus high toxicity ( > grade 3) re: immune-related (IR) toxicities. Results: In this cohort, the response rate was 80%, with 53% of patients experiencing > grade 3 toxicity. There was no significant difference in baseline mutational load in responders (R) vs non-responders (NR) to Ipi/Nivo, but NR had a higher burden of copy number alterations (CNA; p = 0.013), with frequent alterations detected in PTEN, JAK2, and B2M. There were no significant differences in baseline CD8+ T cell density, expression of immune-related genes, or T cell clonality for R vs NR pts. Ipi/Nivo treatment increased intratumoral T cell clonality, but this did not correlate with response. A more diverse peripheral T cell repertoire at baseline was detected in pts who developed IR toxicity (p < 0.05). Conclusions: This data suggests that responses to Ipi/Nivo in mm may occur in the absence of high mutational load or brisk immune infiltrate at baseline. Putative mechanisms of resistance to Ipi/Nivo include high burden of CNA and alterations in PTEN, JAK2, and B2M. Together these studies identify candidate biomarkers of resistance and toxicity for Ipi/Nivo, though they need to be tested in larger cohorts and across cancer types.

A phase II study of oral azacitidine (CC-486) in combination with pembrolizumab (PEMBRO) in patients with metastatic melanoma (MM)

TPS9594

Background: Immune checkpoint inhibitors have impressive response rates and improved survival for many pts with MM, offering durable responses in up to 35% of pts while others have short-lived or no response ( > 40%). A potentially targetable mechanism for immune escape is for cancers to subvert the cellular epigenetic machinery, affecting multiple aspects of the immune response from suppression of tumor antigen expression [such as Cancer Testis Antigens (CTA)] to antigen processing and presentation, thus allowing tumor proliferation to continue undetected. In preclinical models, decitabine (DAC), a DNA hypomethylating agent (HMA), has been able to revert heterogeneous CTA expression profiles, increasing cancer cell immunogenicity. HMAs also increased TH1-chemokine expression, T cell tumor infiltration, T cell-mediated tumor killing, and have been shown to be synergistic with checkpoint inhibitors in preclinical models. This suggests that epigenetic therapy with checkpoint inhibition is a rational combination to target MM. Clinical advantages of the HMA CC-486 over DAC include oral bioavailability and potential versatility in dosing and schedule. We hypothesize that CC-486 + PEMBRO will be tolerated at biologically relevant doses; enhance response to PEMBRO in pts with mm who are PD-1 naïve; and reverse resistance to immunotherapy in pts refractory/resistant to PD-1 directed therapy. Methods: This study will evaluate the safety and efficacy of CC-486 + PEMBRO defined by Objective Response Rate (ORR) by RECIST 1.1 in pts with MM. Pts who are PD-1 naïve (Arm A, n = 36) and pts who have progressed on prior PD-1 directed therapy (Arm B, n = 35) will be enrolled. Unlimited prior systemic therapies will be allowed. Pts will receive 300mg PO of CC-486 on days 1-14 and 200mg IV of PEMBRO every 3 weeks. Continuous monitoring for toxicity and futility will be performed and assumes an ORR of > 35% and > 15% for Arms A and B, respectively (95% power). Tumor biopsies at baseline and post treatment are required. Effects of CC-486 + PEMBRO on CTAs, MDSCs and Tregs, and correlation between mutation burden and response will be studied. This study is open for enrollment. Clinical trial information: NCT02816021.

Association of the diversity and composition of the gut microbiome with responses and survival (PFS) in metastatic melanoma (MM) patients (pts) on anti-PD-1 therapy

3008

Background: Significant advances have been made in cancer therapy with immune checkpoint blockade. However, responses in pts with MM are variable, and insights are needed to identify biomarkers of response and strategies to overcome resistance. There is a growing appreciation of the role of the microbiome in cancer, and evidence in murine models that modulation of the gut microbiome may enhance responses to immune checkpoint blockade, though this has not been well studied in pts. Thus we evaluated the microbiome in a large cohort of pts with MM, focusing on responses to anti-PD-1. Methods: We collected oral (n = 234) and gut microbiome samples (n = 120) on a large cohort of of MM patients (n = 221). Of note, the majority of pts were treated with PD-1 based therapy (n = 105). Pts on anti-PD1 were classified as either responders (R) or non-responders (NR) based on RECIST criteria, and 16S rRNA and whole genome shotgun (WGS) sequencing were performed. Immune profiling (via immunohistochemistry, flow cytometry, cytokines and gene expression profiling) was also done in available pre-treatment tumors at baseline. Results: Significant differences in diversity and composition of the gut microbiome were noted in R vs NR to anti-PD-1, with a higher diversity of bacteria in R vs NR (p = 0.03). Differences were also noted in the composition of gut bacteria, with a higher abundance of Clostridiales in R and of Bacteroidales in NR. Immune profiling demonstrated increased tumor immune infiltrates in R pts , with a higher density of CD8+T cells; this correlated with abundance of specific bacteria enriched in the gut microbiome (r = 0.59, 0.014). Other features of enhanced immunity were also noted, and WGS revealed differential metabolic signatures in R vs NR. Furthermore, diversity (p = 0.009; HR = 7.67) and abundance of specific bacteria in R (p = 0.007; HR = 3.88) was associated with improved PFS to anti-PD-1 therapy. Conclusions: Diversity and composition of the gut microbiome differ in R vs NR pts with MM receiving anti-PD-1 therapy. These have potentially far-reaching implications, though results need to be validated in larger cohorts across cancer types.