407 Preliminary safety, pharmacokinetics/pharmacodynamics, and antitumor activity of XmAb20717, a PD-1 x CTLA-4 bispecific antibody, in patients with advanced solid tumors

Background

XmAb20717 is a humanized bispecific monoclonal antibody that simultaneously targets PD-1 and CTLA-4. We report preliminary data from an ongoing, multicenter, Phase 1 study investigating the safety/tolerability, pharmacokinetics/pharmacodynamics, and clinical activity (RECIST 1.1) of XmAb20717 in patients with selected advanced solid tumors.

Methods

A 3+3 dose-escalation design was used to establish a maximum tolerated (MTD)/recommended dose for evaluation in parallel expansion cohorts, including melanoma, renal cell carcinoma, non-small cell lung cancer (NSCLC), prostate cancer, and a basket of tumor types without an FDA-approved checkpoint inhibitor (CI; n≤20 each). XmAb20717 was administered as an infusion on Days 1 and 15 of each 28-day cycle.

Results

As of 08Jul2020, 109 patients had been treated (table 1), and 30 were continuing treatment. In escalation, 6 dose levels (0.15–10.0 mg/kg) were evaluated (n=34); an MTD was not established. Expansion cohorts were initiated at 10 mg/kg (n=72), and a 15 mg/kg escalation cohort was added (n=3). T-cell proliferation was noted in peripheral blood at doses as low as 3 mg/kg and was highest at 10 mg/kg. At this dose, consistent proliferation of CD8+ and CD4+ T cells was observed, indicative of dual PD-1 and CTLA-4 checkpoint blockade (figure 1). Paired pre- and post-dosing biopsies showed increased intratumoral T-cell infiltration and IFN-response signatures following treatment. Grade 3/4 treatment-related adverse events (TRAEs) reported for ≥3 patients included rash (13%), transaminase elevations (7%), lipase increased (4% [2% with amylase increased]), and acute kidney injury (3%), all considered immune-related. There were 2 Grade 5 TRAEs: immune-mediated pancreatitis (in the presence of pancreatic metastases) and immune-mediated myocarditis (Grade 4) that contributed to respiratory failure. A complete response was reported as the best overall response for 1 patient (melanoma); partial responses were reported for 5 patients (2 melanoma, 2 NSCLC, 1 ovarian). The objective response rate was 13% overall and 21% at 10 mg/kg (6/46 and 6/29 evaluable patients, respectively). All responders had prior CI exposure. Responses were observed only at 10 mg/kg and, within the 10 mg/kg group, appeared to correlate with higher peak serum concentration and area under the curve.

Abstract 407 Table 1

Demographics and baseline characteristics

Abstract 407 Figure 1

Mean change from baseline in percentage of Ki67+ T–cell expression in peripheral blood during first two cycles of XmAb20717

Conclusions

XmAb20717 induced T-cell proliferation in peripheral blood consistent with dual-checkpoint blockade. Preliminary data indicate XmAb20717 was generally well-tolerated and associated with evidence of antitumor activity in CI-pretreated patients with various types of advanced solid tumors.

Trial Registration

NCT03517488

Ethics Approval

The study was approved by each institution’s IRB.

Regulatory T cell control of systemic immunity and immunotherapy response in liver metastasis

Patients with cancer with liver metastasis demonstrate significantly worse outcomes than those without liver metastasis when treated with anti-PD-1 immunotherapy. The mechanism of liver metastases-induced reduction in systemic antitumor immunity is unclear. Using a dual-tumor immunocompetent mouse model, we found that the immune response to tumor antigen presence within the liver led to the systemic suppression of antitumor immunity. The immune suppression was antigen specific and associated with the coordinated activation of regulatory T cells (Tregs) and modulation of intratumoral CD11b+ monocytes. The dysfunctional immune state could not be reversed by anti-PD-1 monotherapy unless Treg cells were depleted (anti-CTLA-4) or destabilized (EZH2 inhibitor). Thus, this study provides a mechanistic understanding and rationale for adding Treg and CD11b+ monocyte targeting agents in combination with anti-PD-1 to treat patients with cancer with liver metastasis.

Prognostic Gene Expression Profiling in Cutaneous Melanoma: Identifying the Knowledge Gaps and Assessing the Clinical Benefit

Importance

Use of prognostic gene expression profile (GEP) testing in cutaneous melanoma (CM) is rising despite a lack of endorsement as standard of care.

Objective

To develop guidelines within the national Melanoma Prevention Working Group (MPWG) on integration of GEP testing into the management of patients with CM, including (1) review of published data using GEP tests, (2) definition of acceptable performance criteria, (3) current recommendations for use of GEP testing in clinical practice, and (4) considerations for future studies.

Evidence Review

The MPWG members and other international melanoma specialists participated in 2 online surveys and then convened a summit meeting. Published data and meeting abstracts from 2015 to 2019 were reviewed.

Findings

The MPWG members are optimistic about the future use of prognostic GEP testing to improve risk stratification and enhance clinical decision-making but acknowledge that current utility is limited by test performance in patients with stage I disease. Published studies of GEP testing have not evaluated results in the context of all relevant clinicopathologic factors or as predictors of regional nodal metastasis to replace sentinel lymph node biopsy (SLNB). The performance of GEP tests has generally been reported for small groups of patients representing particular tumor stages or in aggregate form, such that stage-specific performance cannot be ascertained, and without survival outcomes compared with data from the American Joint Committee on Cancer 8th edition melanoma staging system international database. There are significant challenges to performing clinical trials incorporating GEP testing with SLNB and adjuvant therapy. The MPWG members favor conducting retrospective studies that evaluate multiple GEP testing platforms on fully annotated archived samples before embarking on costly prospective studies and recommend avoiding routine use of GEP testing to direct patient management until prospective studies support their clinical utility.

Conclusions and Relevance

More evidence is needed to support using GEP testing to inform recommendations regarding SLNB, intensity of follow-up or imaging surveillance, and postoperative adjuvant therapy. The MPWG recommends further research to assess the validity and clinical applicability of existing and emerging GEP tests. Decisions on performing GEP testing and patient management based on these results should only be made in the context of discussion of testing limitations with the patient or within a multidisciplinary group.

Abstract 1031: Liver metastasis mediated control of distant tumor-specific immunity and response to checkpoint immunotherapy

Background: PD-1 blockade achieves objective responses in 30-55% of melanoma patients, but there remain 45-70% of patients where it is ineffective, either as a single agent or in combination with anti-CTLA-4. We lack salvage strategies for this population and a mechanistic understanding of checkpoint inhibitor refractory melanoma. Previously, we reported that patients with liver metastasis have worse response rate and survival than those without liver metastasis despite treatment with checkpoint immunotherapy and cutaneous biopsy samples from patients with liver metastasis have significantly less activated tumor-infiltrating lymphocytes (TILs) than those with metastasis elsewhere. However, the mechanism of how liver metastasis influences the systemic antitumor immune response in this context is unclear. We hypothesize that tumor antigen-specific tolerance can be induced when metastatic cells invade the liver, resulting in reduced systemic antitumor immunity and immunotherapy resistance.

Results: In this study, we developed a syngeneic two-site tumor animal model in which tumor cells are injected simultaneously into a subcutaneous (SQ) site and into the liver or other organ sites of wild-type C57BL/6 mice to investigate the unique effects of the intrahepatic tumor on antitumor immunity at a distant site. We found that the presence of tumor or tumor antigen within the liver, as opposed to other organs, reduced systemic antitumor immunity and effector T cell function that is evident at the distant SQ site. Tetramer-based flow cytometry and single cell-RNAseq analysis were done on the TILs within the SQ site and the results suggest that tumor-specific CD8 T cells were preferentially dysfunctional but not sequestered by the liver or clonally deleted, with reduced expression of activation markers and effector cytokines (ICOS, CTLA-4, IFNγ, and TNFα). Collectively, the data suggest a liver and antigen-specific immunoregulatory process mediated by the coordinated activation of Foxp3+ regulatory T cells (with increased expression of CTLA-4 and ICOS) and significant changes in the non-T cell immune composition at the distant SQ site in the liver-tumor bearing mice. Genetic studies using a mouse strain expressing the diphtheria toxin receptor under the control of Foxp3 (Foxp3-DTR) with or without the systemic depletion of Tregs revealed that in the absence of Tregs, there was no difference in the distal immunity against the SQ tumor between mice with and without experimental liver metastasis. Finally, we found that this form of systemic antitumor effector T cell dysfunction was not reversed by anti-PD-1 monotherapy but rather by combination therapy with the deletion (anti-CTLA-4) or destabilization (EZH2 inhibitor) of Tregs, suggesting a distinct regulatory mechanism contributing to anti-PD-1 resistance in the setting of liver metastasis that could be overcome to achieve complete tumor regression at both sites.

Conclusion: Our results reveal a novel mechanism of checkpoint inhibitor resistance and suggest a strategy to improve the outcome of immunotherapy treatments for stage IV cancer patients with liver metastasis.

Citation Format: James C. Lee, Sadaf Mehdizadeh, Arabella Young, Jennifer Bridge, Ilgiz A. Mufazalov, Adil Daud, Jeffrey A. Bluestone. Liver metastasis mediated control of distant tumor-specific immunity and response to checkpoint immunotherapy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1031.

Abstract CT013: SWOG S1320: Improved progression-free survival with continuous compared to intermittent dosing with dabrafenib and trametinib in patients with BRAF mutated melanoma

Background: BRAF and MEK inhibitors yield objective responses in the majority of BRAFV600E/K mutant melanoma patients, but acquired resistance limits response durations. Preclinical data suggests that intermittent dosing of these agents may delay acquired resistance by deselecting tumor cells that grow optimally in the presence of these agents. S1320 is a randomized phase 2 clinical trial designed to determine whether intermittent versus continuous dosing of dabrafenib and trametinib improves progression-free survival (PFS) in patients with advanced BRAFV600E/K melanoma.

Methods: All patients received continuous dabrafenib and trametinib for 8-weeks after which non-progressing patients were randomized to receive either continuous treatment or intermittent dosing of both drugs on a 3-week-off, 5-week-on schedule. Unscheduled treatment interruptions of both drugs for > 14 days were not permitted. Responses were assessed using RECIST v1.1 at 8-week intervals scheduled to coincide with on-treatment periods for patients on the intermittent dosing arm. Adverse events were assessed using CTCAE v4 monthly. The design assumed exponential PFS with a median of 9.4 months using continuous dosing, 206 eligible patients and 156 PFS events. It had 90% power with a two-sided α = 0.2 to detect a change to a median with an a priori hypothesis that intermittent dosing would improve the median PFS to 14.1 months using a Cox model stratified by the randomization stratification factors.

Results: 242 patients were treated and 206 patients without disease progression after 8 weeks were randomized, 105 to continuous and 101 to intermittent treatment. 70% of patients had not previously received immune checkpoint inhibitors. There were no significant differences between groups in terms of baseline patient characteristics. The median PFS was statistically significantly longer, 9.0 months from randomization, with continuous dosing vs. 5.5 months from randomization with intermittent dosing (p = 0.064). There was no difference in overall survival between groups (median OS = 29.2 months in both arms p = 0.93) at a median follow up of 2 years. 77% of patient treated continuously discontinued treatment due to disease progression vs. 84% treated intermittently (p = 0.34).

Conclusions: Continuous dosing with the BRAF and MEK inhibitors dabrafenib and trametinib yields superior PFS compared with intermittent dosing.

Support: NIH/NCI grants CA180888, CA180819, CA180820

Citation Format: Alain Algazi, Megan Othus, Adil Daud, Roger Lo, Janice Mehnert, Thach-Giao Truong, Robert Conry, Kari Kendra, Gary Doolittle, Joseph I. Clark, Michael Messino, Dennis F. Moore, Christopher Lao, Bryan A. Faller, Rangaswamy Govindarajan, Amy Harker-Murray, Luke Dreisbach, James Moon, Kenneth Grossman, Antoni Ribas. SWOG S1320: Improved progression-free survival with continuous compared to intermittent dosing with dabrafenib and trametinib in patients with BRAF mutated melanoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT013.

Exhausted T cell signature predicts immunotherapy response in ER-positive breast cancer

Responses to immunotherapy are uncommon in estrogen receptor (ER)-positive breast cancer and to date, lack predictive markers. This randomized phase II study defines safety and response rate of epigenetic priming in ER-positive breast cancer patients treated with checkpoint inhibitors as primary endpoints. Secondary and exploratory endpoints included PD-L1 modulation and T-cell immune-signatures. 34 patients received vorinostat, tamoxifen and pembrolizumab with no excessive toxicity after progression on a median of five prior metastatic regimens. Objective response was 4% and clinical benefit rate (CR + PR + SD > 6 m) was 19%. T-cell exhaustion (CD8⁺ PD-1⁺/CTLA-4⁺) and treatment-induced depletion of regulatory T-cells (CD4⁺ Foxp3⁺/CTLA-4⁺) was seen in tumor or blood in 5/5 patients with clinical benefit, but only in one non-responder. Tumor lymphocyte infiltration was 0.17%. Only two non-responders had PD-L1 expression >1%. This data defines a novel immune signature in PD-L1-negative ER-positive breast cancer patients who are more likely to benefit from immune-checkpoint and histone deacetylase inhibition (NCT02395627).

Phase II single-arm multi-center study of adjuvant ipilimumab in combination with nivolumab in subjects with high-risk ocular melanoma

TPS10089

Background: Treatment of primary ocular melanoma is often very effective, with local recurrence rates of < 5%. However, distant recurrence is as high as 50% depending on features of the primary tumor. These data emphasize the need for effective adjuvant therapy for patients with locally treated ocular melanoma. Several adjuvant treatments have been developed for patients with high-risk cutaneous melanoma, including ipilimumab and nivolumab monotherapies and an ongoing trial is exploring the nivolumab/ipilimumab combination (CA209-915), but patients with high-risk ocular melanomas have been excluded from these trials. As yet there is no approved adjuvant treatment for high-risk ocular melanoma patients. Methods: We are conducting a Phase II single-arm multi-center study of adjuvant ipilimumab in combination with nivolumab in subjects with high-risk ocular melanoma. This study aims to generate efficacy and safety data for adjuvant this regimen in patients with locally treated high-risk ocular melanoma with 3-year risk of relapse > 50%. The primary endpoint is 3-year relapse-free survival rate. Secondary endpoints are median relapse-free survival, median overall survival, 3-year overall survival rate and safety. All patients will receive nivolumab 240mg IV every 2 weeks plus ipilimumab 1mg/kg IV every 6 weeks. Subjects may receive up to 25 doses of nivolumab and 8 doses of ipilimumab. The accrual goal is 50 patients across all participating institutions. Subjects treated in this study will be matched with controls selected from a contemporaneously collected OM registry, “contemporaneous control” in order to better assess efficacy. Control subjects will be from institutions not participating in this trial, will otherwise meet the trial eligibility criteria and will be further matched with trial participants for various demographic and risk factors to the extent possible. The study is enrolling in 6 comprehensive cancer centers in the US. Clinical trial information: NCT3528408.

Prospective investigation of immunotherapy-induced fatigue by rest and stress echocardiography

e24060

Background: Immune checkpoint inhibitors (ICI) effect durable responses in cancer patients (pts). Myocarditis is rare but fatigue is commonly reported, and whether ICI-induced fatigue is due to subclinical cardiac toxicity is unknown. We hypothesized that pts on ICI develop changes on rest and stress echocardiogram (echo) that correlate with fatigue. Methods: A prospective observational study was performed to monitor cardiac function in pts receiving ICI. Our cohort consisted of pts (n = 10) with stage III/IV melanoma, ECOG 0-1, deemed safe to exercise, without unstable cardiac symptoms. ICI-naïve pts received anti-PD1 alone or in combination with anti-CTLA-4, in adjuvant or metastatic setting. Rest transthoracic echo and dynamic staged exercise stress echo testing was conducted at baseline (prior to ICI) and at 3 and 6 months (mo) following ICI. Various echo parameters at rest and stress were compared. irAEs were detailed and surveys administered at baseline and post-follow up. Results: 10 pts (9 men, mean age 56 yrs) completed baseline cardiac testing of whom 7 completed follow up testing at 6 mo (6 anti-PD1 monotherapy, 1 metastatic combination therapy). Of these 7 pts, 5 (71%) reported increased fatigue per CTCAE at 3 or 6 mo follow up and all 7 had irAEs (3 rash, 1 colitis, 1 diarrhea, 1 hypophysitis, 1 arthralgia, 1 xerostomia). Among resting echo parameters, left ventricular outflow tract velocity time integral (LVOT VTI) was significantly reduced at 6 mo compared to baseline (22.6 ± 3.4 vs 20.0 ± 2.5, p = 0.0047), albeit still within normal range. No other resting echo parameters changed. Among exercise echo parameters, there was no difference in METs achieved, time of exercise, blood pressure or heart rate between time points. Of note, of 7 subjects who completed 6 mo testing, 2 (29%) were unable to achieve previous peak stage of exercise during testing. Conclusions: Though no echo parameter significantly correlating with fatigue was reported, nearly one-third of a small cohort of pts were unable to achieve peak exercise 6 mo after starting ICI. This combined with the statistical reduction in LVOT VTI suggests functional limitation and warrants further study. Post-follow up surveys are pending and may further inform issues important in ICI survivorship. [Table: see text]

Long-term survival from pembrolizumab (pembro) completion and pembro retreatment: Phase III KEYNOTE-006 in advanced melanoma

10013

Background: 5-year follow-up of the phase 3 KEYNOTE-006 study (NCT01866319) showed pembro improved OS vs ipilimumab (ipi) in patients (pts) with advanced melanoma. 3-y OS rate from pembro completion for pts who completed 2 y of pembro was 93.8%. Results with 8 mo of additional follow-up are presented to inform clinical care. Methods: Eligible pts with ipi-naive advanced melanoma, ≤1 prior therapy for BRAF-mutant disease, and ECOG PS 0 or 1 were randomized to pembro 10 mg/kg Q2W or Q3W for ≤2 y or ipi 3 mg/kg Q3W for 4 doses. Pts discontinuing pembro with CR, PR, or SD after ≥94 weeks were considered pts with 2-y pembro. Pts who stopped pembro with SD, PR or CR could receive ≤12 mo of additional pembro (2nd course) upon disease progression if still eligible. ORR was assessed per immune-related response criteria by investigator review. OS was estimated using the Kaplan-Meier method. Pembro arm data were pooled. Post hoc ITT efficacy analyses are shown. Results: Median follow-up from randomization to data cutoff (Jul 31, 2019) was 66.7 mo in the pembro and 66.9 mo in the ipi arms. OS outcomes are shown in Table. For the 103 pts with 2-y pembro (30 CR, 63 PR, 10 SD), median follow-up from completion was 42.9 mo (95% CI, 39.9-46.3).Median DOR was not reached. 36-mo OS from pembro completion was 100% (95% CI, 100.0-100.0) for pts with CR, 94.8% (95% CI, 84.7-98.3) for pts with PR, and 66.7% (95% CI, 28.2-87.8) for pts with SD. 15 pts received 2nd-course pembro; BOR in 1st course was 6 CR, 6 PR, and 3 SD. Median time from end of 1st course to start of 2ndcourse was 24.5 mo (range, 4.9-41.4). Median follow-up in pts who received 2nd-course pembro was 25.3 mo (range, 3.5-39.4). Median duration of 2nd-course pembro was 8.3 mo (range, 1.4-12.6). BOR on 2ndcourse was 3 CR, 5 PR (ongoing responses, 7 pts), 3 SD (ongoing, 2 pts), and 2 PD (1 death); 2 pts pending. Conclusions: Pembro improves the long-term survival vs ipi in pts with advanced melanoma, with all pts who completed therapy in CR still alive at 5 years. Retreatment with pembro at progression in pts who stopped at SD or better can provide additional clinical benefit in a majority of pts. Clinical trial information: NCT01866319. [Table: see text]

Association of prior immune checkpoint blockade (ICB) with longer progression-free survival (PFS) in patients treated with intermittent versus continuous dabrafenib and trametinib: A post-hoc analysis of S1320

10039

Background: S1320 is a phase 2 randomized clinical trial presented at the 2020 AACR Annual Meeting in April demonstrating that continuous dosing of dabrafenib and trametinib yields longer PFS than intermittent dosing of these agents in patients with BRAFV600E/K melanoma. Here we look at the association between prior exposure to ICB and PFS in patients randomized to either intermittent or continuous dosing on S1320. Methods: Patients without disease progression after 8 weeks of dabrafenib and trametinib were randomized 1:1 to proceed with intermittent therapy (3-week-off, 5-week-on) or to stay on the continuous daily dosing schedule. The design called for 206 randomized patients with the primary outcome of PFS. Response assessments were made using RECIST v1.1 at 8-week intervals. A post-hoc analysis assessed differences in PFS in the pool of all randomized patients based on prior exposure to anti-PD1 antibodies, a randomization stratification factor. Kaplan-Meier estimates and multivariable Cox regression models (controlling for pre-randomization age, Zubrod performance status, LDH, unknown primary, M-Stage) were used to evaluate the association between this stratification factor and PFS. Results: Of 242 patients treated on study, 105 were randomized to continuous dosing, 101 to intermittent dosing, and 36 were not randomized due to disease progression at 8 weeks or other factors. 37% of the 242 enrolled and 37% of the 206 randomized patients had previously been treated with ICB. Among all randomized patients, there were no differences in baseline characteristics comparing patients with and without prior immune checkpoint inhibitor exposure: age median 62 vs 59, LDH elevation 37% vs 39%,, stage IVB/C 73% vs 64%, Zubrod performance status 0, 57% vs 58%. PFS was longer in patients with prior ICB exposure (hazard ratio = 0.60, 95% confidence interval 0.41,-0.98, median = 6 vs 9 months from randomization, 8 vs 11 months from starting treatment). There was no difference in the association between prior ICB exposure and PFS between arms (interaction p-value = 0.62). Conclusions: In patients without early progression on dabrafenib and trametinib, PFS was longer with prior to exposure to ICB . Although the groups had similar baseline characteristics and rates of randomization, these results could still be influenced by non-controlled factors influencing clinicians’ decisions to start a patient on immune versus targeted therapy. Clinical trial information: NCT02196181.

Regulatory T cell control of systemic tumor-specific immunity and response to checkpoint immunotherapy response in liver metastasis

A significant number of metastatic melanoma patients have disease progression despite checkpoint inhibitor therapy. We lack salvage strategies for this population and a mechanistic understanding of checkpoint inhibitor refractory disease. Previously, we reported that patients with liver metastasis have worse response rate and survival than those without liver metastasis despite treatment with checkpoint immunotherapy, but how liver metastasis can influence the antitumor immune response in this context is unclear. We hypothesize that tumor antigen-specific tolerance can be induced in the context of liver metastasis, resulting in therapy resistance.

In this study, we developed a syngeneic two-site tumor model in which tumor cells are injected simultaneously into a subcutaneous (SQ) site and into the liver or other organ sites of B6 mice to study the effects of the intrahepatic tumor on antitumor immunity at a distant site. We found that the presence of tumor or tumor antigen within the liver reduced systemic antigen-specific effector T cell function. Tetramer and sc-RNAseq studies suggest a liver and antigen-specific immunoregulatory process associated with the activation of regulatory T cells and the remodeling of innate immune cells. Importantly, this systemic dysfunctional immune state was not reversed by anti-PD-1 monotherapy but rather by deleting (anti-CTLA-4) or destabilizing (EZH2 inhibitor) intratumoral Tregs, suggesting a distinct regulatory mechanism contributing to anti-PD-1 resistance that could be overcome to achieve complete tumor regression at all sites.

Our results reveal a novel mechanism of checkpoint inhibitor resistance and suggest a strategy to improve the outcome for patients with liver metastasis.

O85 Durable responses in anti-PD-1 refractory melanoma following intratumoral injection of a toll-like receptor 9 (TLR9) agonist, CMP-001, in combination with pembrolizumab

Background

Intratumoral (IT) injection of CMP-001, a CpG-A TLR9 agonist packaged within a virus-like particle, is designed to activate tumor-associated plasmacytoid dendritic cells, inducing an interferon-rich tumor microenvironment and anti-tumor CD8+ T cell responses.

Methods

CMP-001-001 is an ongoing Phase 1b trial evaluating the safety and efficacy of CMP-001 in combination with pembrolizumab (Part 1; N = 144) or alone (Part 2; N = 23) in patients with advanced melanoma resistant to prior anti-PD-1 therapy (Tables 1). CMP-001 is administered IT into accessible lesion(s) either with, or without on-site saline dilution (table 1), and response assessed by RECIST v1.1. Monotherapy patients who progress can be rolled over onto combination therapy and continue on study. Baseline and on-therapy serum is analyzed for cytokines, and immunohistochemistry and RNA-Seq are performed on available tumor biopsies.

Abstract O85 Table 1

Advanced anti-PD-1 Refractory melanoma patient population by treatment allocation

Results

Adverse events (AEs) attributed to CMP-001 in combination with pembrolizumab or as monotherapy consisted predominately of transient low-Grade flu-like symptoms and injection site reactions: Grade 3+ related AEs were reported in 33% of patients treated with combination therapy and 22% of patients with monotherapy.

The Objective Response Rate (ORR) with undiluted CMP-001 in combination with pembrolizumab was 24% (18/75; 95% confidence interval: 15%-35% (table 1); on-site dilution of CMP-001 was associated with a substantial decrease in ORR to 12% (7/61; 95% confidence interval: 5%-22% (table 1). Three additional patients had a delayed partial response after an initial period of disease progression. Anti-tumor response was comparable between injected and uninjected lesions. The median duration of response to combination therapy has not been reached. The ORR to CMP-001 monotherapy was 22% (5/23; 95% confidence interval: 7%-44% (table 1); time from last anti-PD-1 therapy before CMP-001 was 1.5 to >20 months in responders; 3 of the patients responding to CMP-001 monotherapy achieved PR at the first evaluation, but progressed by the second evaluation.

Serum and tumor biopsy translational studies in the patients receiving combination therapy supported the proposed mechanism of TLR9 activation and identified a possible association between induction of serum CXCL10 and response.

Conclusions

IT CMP-001 alone and in combination with pembrolizumab appears well tolerated, can reverse resistance to anti-PD-1 therapy, and can produce deep and durable clinical responses in patients with advanced melanoma.

Ethics Approval

CMP-001-001 was centrally approved by the WCG-WIRB, WIRB approval tracking number 20152597.

Regulatory T cells use arginase 2 to enhance their metabolic fitness in tissues

Distinct subsets of Tregs reside in nonlymphoid tissues where they mediate unique functions. To interrogate the biology of tissue Tregs in human health and disease, we phenotypically and functionally compared healthy skin Tregs with those in peripheral blood, inflamed psoriatic skin, and metastatic melanoma. The mitochondrial enzyme, arginase 2 (ARG2), was preferentially expressed in Tregs in healthy skin, increased in Tregs in metastatic melanoma, and reduced in Tregs from psoriatic skin. ARG2 enhanced Treg suppressive capacity in vitro and conferred a selective advantage for accumulation in inflamed tissues in vivo. CRISPR-mediated deletion of this gene in primary human Tregs was sufficient to skew away from a tissue Treg transcriptional signature. Notably, the inhibition of ARG2 increased mTOR signaling, whereas the overexpression of this enzyme suppressed it. Taken together, our results suggest that Tregs express ARG2 in human tissues to both regulate inflammation and enhance their metabolic fitness.

Extended 5-Year Follow-up Results of a Phase Ib Study (BRIM7) of Vemurafenib and Cobimetinib in BRAF-Mutant Melanoma

PURPOSE

To report the 5-year overall survival (OS) landmark and the long-term safety profile of vemurafenib plus cobimetinib (BRAF plus MEK inhibition, respectively) in the BRIM7 study.

PATIENTS AND METHODS

This phase Ib, dose-finding, and expansion study evaluated combination treatment with vemurafenib and cobimetinib in two cohorts of patients with advanced BRAF ^V600-mutated melanoma: patients who were BRAF inhibitor (BRAFi)-naïve (n = 63) or patients who had progressed on prior treatment with BRAFi monotherapy [vemurafenib monotherapy-progressive disease (PD); n = 66]. Patients in the dose-escalation phase received vemurafenib at 720 or 960 mg twice daily in combination with cobimetinib at 60, 80, or 100 mg/d for 14 days on/14 days off, 21 days on/7 days off, or continuously. Two regimens were selected for expansion: vemurafenib (720 and 960 mg twice daily) and cobimetinib (60 mg/d 21/7).

RESULTS

Median OS was 31.8 months [95% confidence interval (CI), 24.5-not estimable] in the BRAFi-naïve cohort. The landmark OS rate plateaued at 39.2% at years 4 and 5 of follow-up. In the vemurafenib monotherapy-PD cohort, the median OS was 8.5 months (95% CI, 6.7-11.1), and the landmark OS rate plateaued at 14.0% from 3 years of follow-up. No increase was observed in the frequency and severity of adverse events with long-term follow-up. No new toxicities were detected, and there was no increase in the frequency of symptomatic MEK inhibitor class-effect adverse events.

CONCLUSIONS

A subset of patients with advanced BRAF ^V600-mutated melanoma treated with a combination regimen of vemurafenib and cobimetinib achieve favorable long-term outcomes.

An analysis of genetic heterogeneity in untreated cancers

Genetic intratumoural heterogeneity is a natural consequence of imperfect DNA replication. Any two randomly selected cells, whether normal or cancerous, are therefore genetically different. Here, we review the different forms of genetic heterogeneity in cancer and re-analyse the extent of genetic heterogeneity within seven types of untreated epithelial cancers, with particular regard to its clinical relevance. We find that the homogeneity of predicted functional mutations in driver genes is the rule rather than the exception. In primary tumours with multiple samples, 97% of driver-gene mutations in 38 patients were homogeneous. Moreover, among metastases from the same primary tumour, 100% of the driver mutations in 17 patients were homogeneous. With a single biopsy of a primary tumour in 14 patients, the likelihood of missing a functional driver-gene mutation that was present in all metastases was 2.6%. Furthermore, all functional driver-gene mutations detected in these 14 primary tumours were present among all their metastases. Finally, we found that individual metastatic lesions responded concordantly to targeted therapies in 91% of 44 patients. These analyses indicate that the cells within the primary tumours that gave rise to metastases are genetically homogeneous with respect to functional driver-gene mutations, and we suggest that future efforts to develop combination therapies have the potential to be curative.

Pembrolizumab versus ipilimumab in advanced melanoma (KEYNOTE-006): post-hoc 5-year results from an open-label, multicentre, randomised, controlled, phase 3 study

BACKGROUND

Pembrolizumab improved progression-free survival and overall survival versus ipilimumab in patients with advanced melanoma and is now a standard of care in the first-line setting. However, the optimal duration of anti-PD-1 administration is unknown. We present results from 5 years of follow-up of patients in KEYNOTE-006.

METHODS

KEYNOTE-006 was an open-label, multicentre, randomised, controlled, phase 3 study done at 87 academic institutions, hospitals, and cancer centres in 16 countries. Patients aged at least 18 years with Eastern Cooperative Oncology Group performance status of 0 or 1, ipilimumab-naive histologically confirmed advanced melanoma with known BRAF^V600 status and up to one previous systemic therapy were randomly assigned (1:1:1) to intravenous pembrolizumab 10 mg/kg every 2 weeks or every 3 weeks or four doses of intravenous ipilimumab 3 mg/kg every 3 weeks. Treatments were assigned using a centralised, computer-generated allocation schedule with blocked randomisation within strata. Exploratory combination of data from the two pembrolizumab dosing regimen groups was not protocol-specified. Pembrolizumab treatment continued for up to 24 months. Eligible patients who discontinued pembrolizumab with stable disease or better after receiving at least 24 months of pembrolizumab or discontinued with complete response after at least 6 months of pembrolizumab and then progressed could receive an additional 17 cycles of pembrolizumab. Co-primary endpoints were overall survival and progression-free survival. Efficacy was analysed in all randomly assigned patients, and safety was analysed in all randomly assigned patients who received at least one dose of study treatment. Exploratory assessment of efficacy and safety at 5 years' follow-up was not specified in the protocol. Data cutoff for this analysis was Dec 3, 2018. Recruitment is closed; the study is ongoing. This study is registered with ClinicalTrials.gov, number NCT01866319.

FINDINGS

Between Sept 18, 2013, and March 3, 2014, 834 patients were enrolled and randomly assigned to receive pembrolizumab (every 2 weeks, n=279; every 3 weeks, n=277), or ipilimumab (n=278). After a median follow-up of 57·7 months (IQR 56·7-59·2) in surviving patients, median overall survival was 32·7 months (95% CI 24·5-41·6) in the combined pembrolizumab groups and 15·9 months (13·3-22·0) in the ipilimumab group (hazard ratio [HR] 0·73, 95% CI 0·61-0·88, p=0·00049). Median progression-free survival was 8·4 months (95% CI 6·6-11·3) in the combined pembrolizumab groups versus 3·4 months (2·9-4·2) in the ipilimumab group (HR 0·57, 95% CI 0·48-0·67, p<0·0001). Grade 3-4 treatment-related adverse events occurred in 96 (17%) of 555 patients in the combined pembrolizumab groups and in 50 (20%) of 256 patients in the ipilimumab group; the most common of these events were colitis (11 [2%] vs 16 [6%]), diarrhoea (ten [2%] vs seven [3%]), and fatigue (four [<1%] vs three [1%]). Any-grade serious treatment-related adverse events occurred in 75 (14%) patients in the combined pembrolizumab groups and in 45 (18%) patients in the ipilimumab group. One patient assigned to pembrolizumab died from treatment-related sepsis.

INTERPRETATION

Pembrolizumab continued to show superiority over ipilimumab after almost 5 years of follow-up. These results provide further support for use of pembrolizumab in patients with advanced melanoma.

FUNDING

Merck Sharp & Dohme.

Abstract CT188: 5-year survival and other long-term outcomes from KEYNOTE-006 study of pembrolizumab (pembro) for ipilimumab (ipi)-naive advanced melanoma

Introduction: Pembro significantly improved OS vs ipi in advanced melanoma in the KEYNOTE-006 study (NCT01866319). We present outcomes from the 5-year follow-up of this study−the longest to date in a randomized phase 3 trial of pembro in advanced cancer. Long-term follow-up for pts completing 2 years of pembro and data for pts treated with a second course (2nd course) of pembro are also reported.

Methods: Eligible pts (N=834) were randomly assigned (1:1:1) to pembro 10 mg/kg Q2W or Q3W for up to 2 years or ipi 3 mg/kg Q3W for 4 doses. Eligible pts who completed pembro or stopped for CR and then progressed could receive an additional 12 mo of pembro if they met inclusion criteria. End points included OS and ORR per irRC by investigator review. Pembro completion was defined as discontinuation with CR, PR, or SD after ≥94 weeks of pembro. Results were pooled from the 2 pembro arms.

Results: At data cutoff (Dec 3, 2018), median follow-up of surviving pts was 57.7 mo (range, 0.03-62.1). Median OS (95% CI) was 32.7 mo (24.5-41.6) in the combined pembro arms (n=556) and 15.9 mo (13.3-22.0) in the ipi arm (n=278) (HR, 0.73). Five-year OS rates (95% CI) were estimated to be 38.7% (34.2-43.1) and 31.0% (25.3-36.9), respectively. For pts receiving first-line pembro, median OS (95% CI) was 38.7 mo (27.3-50.7) in the combined pembro arms (n=368) and 17.1 mo (13.8-26.2) in the ipi arm (n=181) (HR, 0.73); 5-year OS rates (95% CI) were estimated to be 43.2% (38.0-48.3) and 33.0% (25.8-40.3), respectively. A total of 103 (18.5%) pts completed 2 years of pembro; median survival follow-up from pembro completion was 34.5 mo; OS rate at 36 mo was 93.8%. Of the 103 pts, 76 were progression-free and 27 had PD. Median time from pembro end to progression was 16.8 mo (range, 0.99-33.9). Thirteen pts received 2nd course pembro; best overall response (BOR) in 1st course was 6 CR, 6 PR, and 1 SD. Median duration of 2nd-course pembro was 9.7 mo; BOR on 2nd course was 3 CR, 4 PR, 3 SD, and 1 PD (response assessment was pending for 2 pts). All 3 pts with 2nd-course CR and 2 of 4 with PR had ongoing response; the remaining 2 pts who had 2nd-course PR subsequently progressed. Four pts discontinued 2nd-course treatment before 12 mo (2 due to PD, 1 due to G2 interstitial pneumonia, and 1 due to physician decision). Six pts had grade1/2 TRAEs during 2nd-course pembro; there were no grade 3/4 TRAEs or deaths.

Conclusions: Pembro continued to show improved OS vs ipi in 5-year follow-up of pts with advanced melanoma with 43.2% estimated to be alive at 5 years versus 33.0% with ipi. Almost one-fifth of pts completed 2 years of pembro, and 93.8% are estimated to be alive 3 years after pembro completion. Second-course pembro treatment was generally well tolerated and provided additional antitumor activity. These results confirm that 2-year pembro is an effective treatment for pts with advanced melanoma.

Citation Format: Caroline Robert, Jacob Schachter, Georgina V. Long, Ana Arance, Jean-Jacques Grob, Laurent Mortier, Adil Daud, Matteo S. Carlino, Catriona McNeil, Michal Lotem, James Larkin, Paul Lorigan, Bart Neyns, Christian U. Blank, Omid Hamid, Teresa M. Petrella, James Anderson, Clemens Krepler, Scott J. Diede, Antoni Ribas. 5-year survival and other long-term outcomes from KEYNOTE-006 study of pembrolizumab (pembro) for ipilimumab (ipi)-naive advanced melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT188.

PTCH1 Mutation in a Patient With Metastatic Undifferentiated Carcinoma With Clear Cell Change

Clear cell basal cell carcinoma (BCC) is an unusual variant of BCC. Its pathogenesis, prognosis, and optimal management remain poorly described due to its rarity. This report presents a 51-year-old man with a history of excised BCC and cutaneous squamous cell carcinomas of the face, with multiple recurrent poorly differentiated carcinomas with clear cell changes of the shoulder for which further classification using conventional histologic means was not possible. His tumor tissue was sent to Foundation Medicine for testing, which revealed a high number of pathogenic genomic alterations, including a mutation inPTCH1. He was diagnosed with dedifferentiated BCC and started on vismodegib. He developed lung metastases while receiving vismodegib, and his disease continued to progress while he was undergoing treatment in a phase I clinical trial. Given the high number of pathogenic alterations suggestive of high tumor mutational burden, immunotherapy was considered and off-label authorization was obtained for treatment with a PD-1 antibody (pembrolizumab). He had a dramatic disease response after 4 infusions of pembrolizumab. Molecular testing was instrumental in determining the correct diagnosis and formulating appropriate treatment options for this patient. Molecular profiling of metastatic BCCs and its subtypes is essential to the development of effective targeted therapies and combination approaches.

Abstract 4217: Tumor mutational burden (TMB), T cell-inflamed gene expression profile (GEP) and PD-L1 are independently associated with response to pembrolizumab (Pembro) in patients with advanced melanoma in the KEYNOTE (KN)-006 study

Background: Biomarkers may aid in identifying pts who can benefit from checkpoint blockade therapies. Biomarkers of response to anti-PD-1 therapy include TMB and inflammatory biomarkers such as PD-L1 expression and T cell-inflamed GEP. Effects of TMB and GEP on clinical outcomes were evaluated for Pembro (anti-PD-1) and Ipi (anti-CTLA-4) monotherapies in the KN-006 study.

Methods: In this phase 3, controlled, open label study, 834 pts were randomized to receive Pembro 10 mg/kg every 2 or 3 wks or 4 doses of Ipi 3 mg/kg every 3 wks. Data were available for analysis of TMB (whole exome sequencing) in 216 pts (Pembro n=151 and Ipi n=65), for GEP (RNA, NanoString nCounter) in 641 pts (Pembro n=461 and Ipi n=180) and 134 pts had both TMB and GEP data available. All pts with TMB data and 458 pts with GEP data had PD-L1 expression data (PD-L1 IHC 22C3 pharmDx, MEL score). Statistical testing was prespecified prior to merging biomarker and clinical outcome data. Relationships between biomarkers and best overall response (BOR) were assessed by logistic regression and by area under the ROC (AUROC) curve; progression free survival (PFS) and overall survival (OS) by Cox proportional hazards regression. Prespecified cutoffs were -0.318 for GEP and 175 (mutations/exome) for TMB. Clinical data cutoff was Dec 04, 2017.

Results: TMB, GEP and PD-L1 MEL were significantly associated with BOR, PFS and OS in the Pembro arm (p&lt;0.050). Response rates to Pembro therapy were greater in pts who had high levels of both TMB ≥175 and GEP ≥-0.318 or TMB ≥175 and PD-L1 MEL ≥2 compared with those with low levels of these biomarkers (54% vs 14% and 51% vs 33%, respectively). TMB, GEP and PD-L1 MEL remained significantly associated with response to Pembro for BOR and PFS, and in general for OS, when assessed in joint models. TMB showed low correlations with GEP (0.14; p=0.057) and PD-L1 (0.22; p=0.001); GEP and PD-L1 were moderately correlated (0.60; p&lt;0.001). In Ipi-treated pts, TMB was not significantly associated with BOR (p=0.428) and trended toward significance for PFS (0.098) and OS (p=0.099); GEP was also not significantly associated with BOR (p=0.188) but was significantly associated with PFS (p=0.012) and OS (p&lt;0.001). AUROCs (95% CI) were 0.64 (0.55, 0.73) and 0.53 (0.35, 0.70) for TMB, and 0.64 (0.59, 0.7) and 0.56 (0.45, 0.67) for GEP with Pembro and Ipi. Note the observed TMB relationship with Ipi is based on an assessment of limited data in that arm and definitive conclusions cannot be made.

Conclusion: TMB and inflammatory biomarkers (GEP and PD-L1) showed statistically significant and independent associations with BOR, PFS and OS in Pembro-treated pts with advanced melanoma. Only GEP showed significant associations with PFS and OS for Ipi, potentially indicating a prognostic value.

Citation Format: Antoni Ribas, Caroline Robert, Jacob Schachter, Georgina V. Long, Ana Arance, Matteo S. Carlino, James Larkin, Andrea L. Webber, Jared Lunceford, Qing Zhao, Razvan Cristescu, Michael Nebozhyn, Chunsheng Zhang, Wendy Blumenschein, Clemens Krepler, Nageatte Ibrahim, Adil Daud, Jean-Jacques Grob. Tumor mutational burden (TMB), T cell-inflamed gene expression profile (GEP) and PD-L1 are independently associated with response to pembrolizumab (Pembro) in patients with advanced melanoma in the KEYNOTE (KN)-006 study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4217.

Response to PD-1 inhibition in early- and late-relapsing cutaneous melanoma

e21038

Background: Up to 45% of stage I-II melanomas will relapse within 5 years, and some relapses occur more than 10 years after surgical resection. Little is known about the differences in tumor characteristics, including immunogenicity, of early- vs. late-relapsing melanoma, or the implication of these differences in response to PD-1 inhibition. Methods: A retrospective cohort study was conducted to compare time from definitive treatment of localized melanoma to relapse with response to pembrolizumab. Patients with prior stage I-II melanoma who relapsed, and then treated with pembrolizumab, were included in the study. Time to relapse was compared with overall response rate. Results: Among the study population, 66 patients initially presented with early stage disease that relapsed within the study period. The median time to relapse was 5 years (range 0.5-33 years, interquartile range 7.25, Q1 = 2, Q2 = 9.25). 9 patients (14%) relapsed within 2 years of surgery; these patients had a higher overall response rate to pembrolizumab than late-relapsing patients with marginal significance (88% vs 50%, p = 0.056). The difference became less significant when patients who relapsed before or after 5 years (70% vs 47%, respectively, p = 0.20), and before or after 10 years (64% vs 45%, p = .31). Conclusions: Patients with early-relapsing melanoma had higher ORR to pembrolizumab than patients with late-relapsing disease, with early relapse defined as earlier than 2 years from definitive surgical intervention. Late relapsing tumors may harbor mechanisms of resistance to immune checkpoint inhibition.

Phase II single-arm multicenter study of adjuvant ipilimumab in combination with nivolumab in subjects with high-risk ocular melanoma

TPS9604

Background: Treatment of primary ocular melanoma is often very effective, with local recurrence rates of < 5%. However, distant recurrence is as high as 50% depending on features of the primary tumor. These data emphasize the need for effective adjuvant therapy for patients with locally treated ocular melanoma. Several adjuvant treatments have been developed for patients with high-risk cutaneous melanoma, including ipilimumab and nivolumab monotherapies and an ongoing trial is exploring the nivolumab/ipilimumab combination (CA209-915), but patients with high-risk ocular melanomas have been excluded from these trials. As yet there is no approved adjuvant treatment for high-risk ocular melanoma patients. Methods: We are conducting a Phase II single-arm multi-center study of adjuvant ipilimumab in combination with nivolumab in subjects with high-risk ocular melanoma. This study aims to generate efficacy and safety data for adjuvant this regimen in patients with locally treated high-risk ocular melanoma with 3-year risk of relapse > 50%. The primary endpoint is 3-year relapse-free survival rate. Secondary endpoints are median relapse-free survival, median overall survival, 3-year overall survival rate and safety. All patients will receive nivolumab 240mg IV every 2 weeks plus ipilimumab 1mg/kg IV every 6 weeks. Subjects may receive up to 25 doses of nivolumab and 8 doses of ipilimumab. The accrual goal is 50 patients across all participating institutions. Subjects treated in this study will be matched with controls selected from a contemporaneously collected OM registry, “contemporaneous control” in order to better assess efficacy. Control subjects will be from institutions not participating in this trial, will otherwise meet the trial eligibility criteria and will be further matched with trial participants for various demographic and risk factors to the extent possible. The study is enrolling in 6 comprehensive cancer centers in the US. Clinical trial information: NCT03528408.

Lenvatinib (len) plus pembrolizumab (pembro) in patients (pts) with advanced melanoma previously exposed to anti–PD-1/PD-L1 agents: Phase 2 LEAP-004 study

TPS9594

Background: Pembro, a PD-1 inhibitor, has shown effective antitumor activity, deep and durable responses, and survival benefit in treatment-naive pts and those with previously treated metastatic melanoma. Len, a potent inhibitor of VEGF receptors 1-3, FGF receptors 1-4, PDGF receptor α, RET, and KIT, combined with a PD-1 inhibitor showed antitumor activity superior to either agent alone in preclinical models of colorectal and lung cancer. Additionally, len plus pembro showed anti-tumor activity and was well-tolerated (24-wk ORR, 47.6%; TRAE: gr 3/4, 67%; gr 5, 0%) in pts with advanced melanoma previously treated with 0-2 therapies in the phase 1b/2 KEYNOTE-146 trial. The efficacy and safety of len plus pembro combination therapy will be evaluated in an open-label, phase 2 trial of pts with advanced melanoma that progressed on PD-1/PD-L1 inhibitor therapy (NCT03776136). Methods: Key inclusion criteria: age ≥18 years, histologically/cytologically confirmed unresectable stage III-IV melanoma that progressed (per iRECIST) within 12 weeks of last dose of an approved PD-1/PD-L1 inhibitor therapy (≥2 doses as monotherapy or combined with other therapies), measurable disease, ECOG PS 0/1, no active autoimmune disease, and adequate organ function. Pts must provide a baseline tumor sample. Pts will receive len 20 mg/day orally plus pembro 200 mg IV Q3W for approximately 2 years (35 doses of pembro), after which they may receive len alone until PD or unacceptable toxicity. Response will be assessed per RECIST v1.1 based on blinded independent central review (BICR) Q9W until week 54, Q12W until week 102, and Q24W thereafter. Pts with CR may discontinue treatment after ≥24 weeks of therapy; eligible pts may continue treatment beyond initial RECIST- or iRECIST-defined PD. AEs will be assessed throughout treatment and for 90 days (120 days for serious AEs) after last dose and graded per NCI CTCAE v4.0. Pts will be followed-up for survival status Q12W. The primary efficacy end point is ORR per modified RECIST v1.1 (BICR). Key secondary end points are PFS and DOR per modified RECIST v1.1 (BICR), OS, and safety; an exploratory biomarker analysis is planned. Clinical trial information: NCT03776136.

Prospective cardiac function monitoring in immunotherapy-treated patients

e14157

Background: Immune checkpoint inhibitors (ICI) demonstrate activity and long-term benefit in melanoma and other cancers. While certain immune-related toxicities have been well described, cardiac toxicities remain poorly characterized. We sought to characterize changes in cardiac function in advanced melanoma patients (pts) starting ICI treatment. Methods: A prospective, observational, single institution trial was performed to monitor cardiac function in pts receiving ICI. Eligible pts were adults with stage III/IV melanoma and ECOG 0-1, determined safe to exercise and without unstable cardiac symptoms. Pts received PD-1 monotherapy or combination ipilimumab/pembrolizumab. Rest and exercise stress cardiac testing (EKG, echocardiography) was conducted at baseline, at 3 months (mo), and at 6 mo. Patient-reported surveys were administered at baseline and at 6 mo. Results: Between Feb 2018 to Jan 2019, we prospectively identified 8 pts who completed baseline cardiac testing. As of Feb 2019, 6 pts completed 3-mo testing, and 4 completed 6-mo testing. Mean age was 57 years (range 34-68). 5 pts received pembrolizumab or nivolumab monotherapy, and 3 received ipilimumab/pembrolizumab. Resting LVOT-VTI decreased from 23.1±2.8 cm at baseline to 20.7±2.8cm at 6 mo (p = 0.047). Maximum HR at peak exercise decreased over time from 149.7±13 bpm at baseline to 114±20.5 bpm at 6 mo (p = 0.085) with concurrent decrease in maximum BP. Enrollment is ongoing. Conclusions: These data suggest measurable changes in left ventricular cardiac function at rest over time, in a prospective cohort of ICI-treated advanced melanoma pts. Further, we observe progressive loss of chronotropic and blood pressure response to exercise. These data have important implications for cancer survivorship in the era of immunotherapy. Updated data to be presented at the meeting include correlation with patient-reported symptoms. [Table: see text]