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LBA4500 Background: Patients (pts) who undergo resection of renal cell carcinoma (RCC) with curative intent remain at risk for disease relapse. We conducted a phase III, double-blind, placebo (PB)-controlled, intergroup study to determine the effect of adjuvant treatment with the mTOR inhibitor everolimus (EVE) on recurrence-free survival (RFS). Methods: Pts with treatment-naïve, non-metastatic, fully-resected RCC at intermediate high- (pT1 G3-4 N0 to pT3a G1-2 N0) or very high-risk (pT3a G3-4 to pT4 G-any or N+) for recurrence were randomized 1:1 to EVE 10 mg PO daily x 54 weeks or PB within 12 weeks of radical or partial nephrectomy. Randomization was stratified by risk group, histology (clear vs. non-clear cell), and performance status (0 vs. 1). RFS was the primary end point; secondary endpoints included overall survival (OS) and adverse events (AEs). The study was designed to detect an 18% reduction in the risk of RFS with EVE compared to PB, corresponding to an improvement of median RFS from 6.75 (based on E2805 ASSURE) to 8.23 years. Final analysis, using a stratified logrank test, was to occur after 804 total events or by 3/2022, whichever occurred first. Results: Between 4/2011 and 9/2016, 1545 pts were randomized to EVE (n = 775) or PB (n = 770). Overall pt characteristics included: intermediate high-/very high-risk 45%/55%; clear cell/non-clear cell 83%/17%. The DSMC recommended study continuation after each of 4 pre-specified interim analyses. 556 DFS events among 1499 eligible pts occurred by the time of final study analysis on 2/23/2022. The median follow-up was 76 months. RFS was improved with EVE vs. PB (HR 0.85, 95% CI, 0.72 – 1.00; P1-sided= 0.0246), narrowly missing the pre-specified, one-sided significance level of 0.022 which accounted for interim analyses. Median RFS was not reached; the 6-year RFS estimate was 64% for EVE and 61% for PB. RFS improvement with EVE vs. PB was observed in the very high-risk group (HR 0.79, 95% 0.65-0.97; P1-sided= 0.011) but not in the intermediate high-risk group (HR 0.99, 95% CI 0.73-1.35, P1-sided= 0.48) ( P for interaction = 0.22). With 290 deaths, OS was similar between arms (HR 0.90, 95% CI, 0.71 – 1.13; P1-sided= 0.178). Fewer pts completed all 54 weeks of study treatment in the EVE group (45% v 69%). In the EVE group, 37% withdrew due to AEs (vs 5% in PB). Grade 3-4 AEs occurred in 46% of pts treated with EVE and 11% with PB. The most common grade 3-4 AEs were mucositis (14% v 0%), hypertriglyceridemia (11% vs. 2%), and hyperglycemia (5% vs. 0%). Conclusions: Adjuvant EVE improved RFS in RCC pts after nephrectomy, but the nominal significance level was narrowly missed. The RFS improvement was seen despite a high rate of early treatment discontinuation. A 21% improvement in RFS with EVE was observed in pts with very high-risk disease, a group for whom adjuvant therapy may be most relevant. Clinical trial information: NCT01120249.

2619 Background: Immune checkpoint inhibitors (ICIs) have made significant improvements in the treatment of cancer patients (pts), but many continue to experience primary or secondary resistance. Here, we leveraged clinical and genomic data to identify prognostic biomarkers in pts treated with ICIs utilizing a pan-cancer approach. Methods: Pts were enrolled to the Total Cancer Care protocol across 18 cancer centers within the Oncology Research Information Exchange Network (ORIEN). RNA-seq was performed on tumors following the RSEM pipeline and gene expressions were quantified as Transcript Per Million (TPM) and were logarithmically normalized. An Auto-Encoder Survival Deep Network (AE-SDN) architecture was developed that combined the reconstruction loss of AE with Cox regression for modeling time to event. For comparison, immunoscore for each pt was calculated based on the estimated densities of tumor CD3+ and CD8+ T cells (Galon, 2020) utilizing CIBERSORTx. The quality of overall survival (OS) predictions was assessed using Harrell’s concordance index (C-index). Log-rank test was used to assess stratified group differences (by ICI or cancer histology) along with Kaplan-Meier (KM) survival analysis of AE-SDN and immunoscore. Results: Pts (n=522) with 4 cancer types including melanoma (n=125), renal cell carcinoma (n=149), non-small cell lung cancer (n=128) and head and neck cancer (n=120) treated with 6 ICI regimens were included in this analysis. ICI regimens were nivolumab (n=219), pembrolizumab (n=202), ipilimumab+nivolumab (n=69), ipilimumab (n=30), avelumab (n=1) and cemiplimab (n=1). The Table summarizes the overall C-index and associated 95% CIs and log-rank P values for the entire cohort (regardless of histology) resulting from our proposed AE-SDN model and the separate estimated immunoscore categorization. AE-SDN top selected genes were mostly related to immunity, carcinogenesis and tumor suppression. The corresponding KM plots showed significantly wider separations of the survival curves in favor of our proposed AE-SDN model relative to the immunoscore with more than 20% improvement in prediction power. Conclusions: Deep network machine learning analysis is a promising approach to identifying relevant prognostic biomarkers in cancer pts treated with ICI. This may lead to novel therapeutic predictive signatures and identification of mechanisms of ICI resistance. Our AE-SDN gene expression signature was significantly prognostic and outperformed the estimated CD3+, CD8+ T Cell immunoscore. Further refinements to our prediction power are ongoing along with more advanced neural network architectures to elucidate related functional pathways. [Table: see text]

2618 Background: Despite the significant improvements in treating cancer with immune checkpoint inhibitors (ICIs), many patients (pts) do not achieve disease control. Using Oncology Research Information Exchange Network (ORIEN) Avatar real-world data conducted under the Total Cancer Care protocol we investigate predictive biomarkers of ICI benefits in pts with advanced malignancies. Methods: Clinical data were normalized as part of ORIEN Avatar. RNA-seq was performed on tumor samples following the RSEM pipeline and gene expressions were quantified as Transcript Per Million (TPM). Gene expressions (GE) were log2(TPM+1) transformed. Mann-Whitney U-test was used to compute differences between groups, and Kaplan-Meier survival analysis was performed. Results: Pts (n=1214) with 27 cancer types treated with ICIs were retrieved from the database, where 1143 and 875 patients were profiled by WES and RNA-seq, respectively. 804 pts had both WES and RNA-seq data. The top six cancer types were renal cell carcinoma (n=206), non-small cell lung cancer (n=173), head and neck cancer (n=157), melanoma (n=154), sarcomas (n=99) and bladder cancer (n=87). The ICI regimens included therapy with atezolizumab (n=87), avelumab (n=12), cemiplimab (n=6), ipilimumab (n=47), nivolumab (n=424), pembrolizumab (n=525) and ipilimumab+nivolumab (n=113). Median overall survival (OS) for the entire cohort was 21.9 months. Patients had significant improvement in OS if ICI was given in the first line ( P

TPS9589 Background: The treatment of melanoma has improved markedly with the emergence of new immune therapies, and both anti-PD-1 monotherapy and the combination of the anti-PD-1 antibody nivolumab and anti-CTLA-4 therapy ipilimumab are now considered standard-of-care in the unresectable or metastatic (advanced) melanoma setting. However, many patients have primary or acquired resistance to these therapies, thereby underpinning the need for more effective approaches. IO102-IO103 is a potentially first-in-class, dual-antigen, immune-modulatory therapy targeting the key cancer immune resistance pathways mediated by IDO and PD-L1. The ability of IO102 and IO103 to respectively activate the specific T cells that recognize these checkpoint molecules and directly modulate immune regulation has previously been demonstrated both preclinically and in human clinical trials. A synergistic anti-tumor response upon treatment against both IDO and PD-L1 has also previously been demonstrated in a preclinical model where IDO and PD-L1 were expressed by different cells in the tumor microenvironment. Due to the distinctive mechanisms of action of IO102-IO103 and anti-PD-1 antibodies, there may be a further synergistic effect when treatment is combined. A previous Phase 1/2 trial investigating the use of IO102-IO103 plus nivolumab in patients with anti-PD-1-naïve metastatic melanoma has demonstrated promising anti-tumor activity with an overall response rate (ORR) of 80%, median progression-free survival (PFS) of 26 months and a manageable safety profile (NCT03047928; Kjeldsen et al, Nat Med 2021). Methods: This is a Phase 3, multicenter, open-label, randomized, 2-arm trial investigating the efficacy and safety of IO102-IO103 plus pembrolizumab versus pembrolizumab alone (EudraCT: 2021-004594-32; ClinicalTrials.gov No: NCT05155254). Inclusion criteria include: adult patients with untreated, unresectable (Stage III), or metastatic (Stage IV) melanoma; > 6 months since last dose of (neo)adjuvant treatment with targeted or immune therapy (in those previously treated); and ≥1 measurable lesion by RECIST v1.1. Primary endpoint is PFS by blinded independent central review. Secondary endpoints include ORR, durable response rate, complete response rate, duration of response, time to response, disease control rate, overall survival, and safety/tolerability. Target enrollment is 300 patients at > 100 sites in 20 countries. Patients are randomized 1:1 to receive either pembrolizumab 200 mg intravenously (IV) every 3 weeks up to 2 years or pembrolizumab 200 mg IV every 3 weeks up to 2 years with dual-antigen IO103-IO102 85-85 µg and Montanide adjuvant subcutaneously on Day 1 and 8 of cycle 1 and 2 and on Day 1 of each cycle thereafter. Enrolment for the study is ongoing. Clinical trial information: EudraCT: 2021-004594-32; ClinicalTrials.gov No: NCT05155254.

Purpose BRAFV600 mutations are frequently found in several glioma subtypes, including pleomorphic xanthoastrocytoma (PXA) and ganglioglioma and much less commonly in glioblastoma. We sought to determine the activity of vemurafenib, a selective inhibitor of BRAFV600, in patients with gliomas that harbor this mutation. Patients and Methods The VE-BASKET study was an open-label, nonrandomized, multicohort study for BRAFV600-mutant nonmelanoma cancers. Patients with BRAFV600-mutant glioma received vemurafenib 960 mg twice per day continuously until disease progression, withdrawal, or intolerable adverse effects. Key end points included confirmed objective response rate by RECIST version 1.1, progression-free survival, overall survival, and safety. Results Twenty-four patients (median age, 32 years; 18 female and six male patients) with glioma, including malignant diffuse glioma (n = 11; six glioblastoma and five anaplastic astrocytoma), PXA (n = 7), anaplastic ganglioglioma (n = 3), pilocytic astrocytoma (n = 2), and high-grade glioma, not otherwise specified (n = 1), were treated. Confirmed objective response rate was 25% (95% CI, 10% to 47%) and median progression-free survival was 5.5 months (95% CI, 3.7 to 9.6 months). In malignant diffuse glioma, best response included one partial response and five patients with stable disease, two of whom had disease stabilization that lasted more than 1 year. In PXA, best response included one complete response, two partial responses, and three patients with stable disease. Additional partial responses were observed in patients with pilocytic astrocytoma and anaplastic ganglioglioma (one each). The safety profile of vemurafenib was generally consistent with that of previously published studies. Conclusion Vemurafenib demonstrated evidence of durable antitumor activity in some patients with BRAFV600-mutant gliomas, although efficacy seemed to vary qualitatively by histologic subtype. Additional study is needed to determine the optimal use of vemurafenib in patients with primary brain tumors and to identify the mechanisms driving differential responses across histologic subsets.

Purpose We evaluated the combination of talimogene laherparepvec plus ipilimumab versus ipilimumab alone in patients with advanced melanoma in a phase II study. To our knowledge, this was the first randomized trial to evaluate addition of an oncolytic virus to a checkpoint inhibitor. Methods Patients with unresectable stages IIIB to IV melanoma, with no more than one prior therapy if BRAF wild-type, no more than two prior therapies if BRAF mutant, measurable/injectable disease, and without symptomatic autoimmunity or clinically significant immunosuppression were randomly assigned 1:1 to receive talimogene laherparepvec plus ipilimumab or ipilimumab alone. Talimogene laherparepvec treatment began in week 1 (first dose, ≤ 4 mL × 106 plaque-forming units/mL; after 3 weeks, ≤ 4 mL × 108 plaque-forming units/mL every 2 weeks). Ipilimumab (3 mg/kg every 3 weeks; up to four doses) began week 1 in the ipilimumab alone arm and week 6 in the combination arm. The primary end point was objective response rate evaluated by investigators per immune-related response criteria. Results One hundred ninety-eight patients were randomly assigned to talimogene laherparepvec plus ipilimumab (n = 98), or ipilimumab alone (n = 100). Thirty-eight patients (39%) in the combination arm and 18 patients (18%) in the ipilimumab arm had an objective response (odds ratio, 2.9; 95% CI, 1.5 to 5.5; P = .002). Responses were not limited to injected lesions; visceral lesion decreases were observed in 52% of patients in the combination arm and 23% of patients in the ipilimumab arm. Frequently occurring adverse events (AEs) included fatigue (combination, 59%; ipilimumab alone, 42%), chills (combination, 53%; ipilimumab alone, 3%), and diarrhea (combination, 42%; ipilimumab alone, 35%). Incidence of grade ≥ 3 AEs was 45% and 35%, respectively. Three patients in the combination arm had fatal AEs; none were treatment related. Conclusion The study met its primary end point; the objective response rate was significantly higher with talimogene laherparepvec plus ipilimumab versus ipilimumab alone. These data indicate that the combination has greater antitumor activity without additional safety concerns versus ipilimumab.

Purpose The multicohort phase Ib KEYNOTE-028 (NCT02054806) study was designed to evaluate the safety and efficacy of pembrolizumab, an anti–programmed death 1 monoclonal antibody, in patients with programmed death ligand 1 (PD-L1) –positive advanced solid tumors. The results from the advanced endometrial cancer cohort are reported. Patients and Methods Female patients with locally advanced or metastatic PD-L1–positive endometrial cancer who had experienced progression after standard therapy were eligible. Patients received pembrolizumab 10 mg/kg every 2 weeks for up to 24 months or until progression or unacceptable toxicity. Primary efficacy end point was objective response rate by RECIST (version 1.1). Secondary end points included safety, duration of response (DOR), progression-free survival, and overall survival. The data cutoff was February 17, 2016. Results Of 75 patients screened, 36 (48.0%) had PD-L1–positive tumors, and 24 (32.0%) were enrolled. Fifteen (62.5%) of these 24 patients had received at least two previous lines of therapy for advanced disease. Three patients (13.0%) achieved confirmed partial response (95% CI, 2.8% to 33.6%); the median DOR was not reached. Two patients were still receiving treatment and exhibiting continued response at time of data cutoff. Three additional patients (13.0%) achieved stable disease, with a median duration of 24.6 weeks. One patient who achieved partial response had a polymerase E mutation. Thirteen patients (54.2%) experienced treatment-related adverse events (AEs), with fatigue (20.8%), pruritus (16.7%), pyrexia (12.5%), and decreased appetite (12.5%) occurring in ≥ 10% of patients. Grade 3 treatment-related AEs were reported in four patients. No patient experienced a grade 4 AE, and no patient discontinued treatment because of an AE. Conclusion Pembrolizumab demonstrated a favorable safety profile and durable antitumor activity in a subgroup of patients with heavily pretreated advanced PD-L1–positive endometrial cancer.

2556 Background: Depletion of tumor-infiltrating CD25+ regulatory T cells (Tregs), which inhibit tumor-specific immune responses, could contribute to tumor eradication. Cami (ADCT-301), an anti-CD25, pyrrolobenzodiazepine-based antibody-drug conjugate, targets CD25+ Tregs. A mouse surrogate has shown potent antitumor activity in solid tumor models. Here we report preliminary data from the monotherapy arm of a phase 1b trial of Cami in pts with selected advanced solid tumors. Methods: The monotherapy dose-escalation part of this open-label study enrolled pts (aged ≥18 years) with selected advanced solid tumors and no suitable existing therapy. The primary objective was to characterize safety and tolerability, and to identify the recommended phase 2 dose of Cami monotherapy. Secondary and exploratory objectives included evaluation of preliminary antitumor activity, pharmacokinetics (PK), pharmacodynamics (PD), and immunogenicity. Pts received Cami every 3 weeks (1 cycle) with dose escalation per a 3+3 design. Disease control rate (DCR) was assessed (complete and partial responses [CR, PR] and stable disease). Results: At data cut-off (Dec 17, 2020), 44 pts were enrolled, with primary tumor types (stage IVA/B: 27 pts; 61.4%) of colorectal (15 pts; 34.1%), pancreatic (14 pts; 31.8%), head and neck, ovarian/fallopian tube, and renal cell carcinoma (all 3 pts; 6.8%), non-small cell lung cancer (2 pts; 4.5%), gastric, esophageal/GEJ, melanoma, and triple-negative breast cancer (each 1 pt; 2.3%). Median (range) age was 60.5 (33–82) years; median (range) number of prior systemic therapies was 4 (1–9). Pts received a median (range) of 2 (1–6) Cami cycles at doses of 20–150 µg/kg. Median (range) treatment duration was 22 (1–178) days. No dose-limiting toxicities were reported. The maximum tolerated dose (MTD) was not reached. All-grade treatment-emergent adverse events (TEAEs) in ≥20% pts were nausea (18 pts; 40.9%), decreased appetite and fatigue (each 16 pts; 36.4%), constipation (13 pts; 29.5%), abdominal pain (11 pts; 25%), and rash (10 pts; 22.7%). The only Grade ≥3 TEAE in ≥10% pts was anemia (5 pts; 11.4%). Grade 3 autoimmune AEs (colitis, immune-mediated AE, systemic inflammatory response syndrome) and neurologic AEs (dysphagia and asthenia, but not GBS) were reported in 3 (6.8%) and 2 (4.5%) pts, respectively. 1 (2.3%) Cami-related TEAE led to treatment withdrawal; no Cami-related TEAEs were fatal. DCR was 25% (95% CI: 11.1, 34.7); 11/44 pts attained stable disease. No pts had CR or PR. Conclusions: Dose escalation of Cami monotherapy is complete. The safety profile is encouraging and MTD was not reached. PK/PD data will be presented. 150 µg/kg is the highest dose investigated for single-agent Cami and the highest to be investigated combined with pembrolizumab in selected advanced solid tumors in the current protocol. Funding: ADC Therapeutics SA NCT03621982. Clinical trial information: NCT03621982.

Purpose Combining immunotherapeutic agents with different mechanisms of action may enhance efficacy. We describe the safety and efficacy of talimogene laherparepvec (T-VEC; an oncolytic virus) in combination with ipilimumab (a cytotoxic T-lymphocyte–associated antigen 4 checkpoint inhibitor) in patients with advanced melanoma. Methods In this open-label, multicenter, phase Ib trial of T-VEC in combination with ipilimumab, T-VEC was administered intratumorally in week 1 (106 plaque-forming units/mL), then in week 4 and every 2 weeks thereafter (108 plaque-forming units/mL). Ipilimumab (3 mg/kg) was administered intravenously every 3 weeks for four infusions, beginning in week 6. The primary end point was incidence of dose-limiting toxicities. Secondary end points were objective response rate by immune-related response criteria and safety. Results Median duration of treatment with T-VEC was 13.3 weeks (range, 2.0 to 95.4 weeks). Median follow-up time for survival analysis was 20.0 months (1.0 to 25.4 months). Nineteen patients were included in the safety analysis. No dose-limiting toxicities occurred, and no new safety signals were detected. Grade 3/4 treatment-related adverse events (AEs) were seen in 26.3% of patients; 15.8% had AEs attributed to T-VEC, and 21.1% had AEs attributed to ipilimumab. The objective response rate was 50%, and 44% of patients had a durable response lasting ≥ 6 months. Eighteen-month progression-free survival was 50%; 18-month overall survival was 67%. Conclusion T-VEC with ipilimumab had a tolerable safety profile, and the combination appeared to have greater efficacy than either T-VEC or ipilimumab monotherapy.

5080 Background: Axitinib (AXI) plus pembrolizumab (pembro) showed superior overall survival (OS), progression-free survival (PFS) and response rate compared with sunitinib in a randomized Phase 3 trial in advanced renal cell carcinoma (RCC). Here, we report long-term efficacy and safety data of the combination AXI/pembro from the Phase 1 trial, with almost 5 years of follow-up. Methods: 52 treatment-naïve patients with advanced RCC were enrolled between 23 September 2014 and 13 October 2015, and were treated with oral AXI 5 mg twice daily and intravenous pembro 2 mg/kg every 3 weeks. Planned treatment duration was 2 years for pembro and not limited for AXI. Based on International Metastatic Database Consortium (IMDC) criteria, 46.2%, 44.2% and 5.8% of patients were reported as having favourable, intermediate and poor risk. Results: At data cut-off date (July 3, 2019), median OS was not reached; 38 (73.1%) patients were alive. 14 (26.9%) patients had died, none were related to treatment. The probability of being alive was 96.1% (95% CI 85.2–99.0) at 1 year, 88.2% (95% CI 75.7– 94.5) at 2 years, 82.2 % (95% CI 68.5– 90.3) at 3 years, and 66.8 % (95% CI 49.1–79.5) at 4 years. Median PFS was 23.5 (95% CI 15.4–30.4) months. Median duration of response was 22.1 (95% CI 15.1–not evaluable) months. Median time on treatment with the combination AXI/pembro was 14.5 months (n=52), median time on pembro after AXI discontinuation was 9.0 months (n=10), and median time on AXI after pembro discontinuation was 7.5 months (n=11). After stopping study treatment, 22 patients received subsequent systemic therapy, including nivolumab and cabozantinib (n=6 each). Grade 3/4 AEs were reported in 38 (73.1%) patients. 20 (38.5%) patients discontinued either drug due to AEs: 17 (32.7%) patients discontinued AXI, and 13 (25.0%) patients discontinued pembro with 10 (19.2%) discontinuing both drugs. Dose reduction of AXI due to AEs was reported in 16 (30.8%) patients. The most common AEs reported were diarrhea (84.6%), fatigue (80.8%), hypertension (53.8%), cough (48.1%), and dysphonia (48.1%). Increased alanine aminotransferase and aspartate aminotransferase occurred in 44.2% and 36.5% of patients, respectively. With this longer follow-up, there were no cumulative AEs or new AEs. OS by IMDC risk group will be presented. Conclusions: In patients with advanced RCC with almost 5 years of follow-up, the combination of AXI/pembro continues to demonstrate clinical benefit with no new safety signals. Clinical trial information: NCT02133742 .

10029 Background: This is the first randomized trial testing the addition of an oncolytic virus to an immune checkpoint inhibitor for advanced melanoma. At the 3-year (yr) follow-up, the combination (combo) of T-VEC and ipi demonstrated durable and statistically superior objective response rate (ORR) over ipi alone (36.7% vs. 16.0%; odds ratio, 3.0; 95% Cl, 1.6–6.0; P = 0.002). Complete response (CR) rate was 21.4% with the combo and 6.0% with ipi. Median overall survival (OS) was not reached in either arm. In this post hoc analysis, we utilized the 3-yr landmark data to explore the relationship between CR and OS in the combo arm. Methods: Pts with unresectable, stage IIIB-IV melanoma were randomized 1:1 to receive combo or ipi alone. T-VEC was administered intratumorally on day 1 of week (wk) 1 at 106 plaque-forming units (PFU)/mL followed by subsequent doses at 108 PFU/mL on day 1 of wk 4, and every 2 wks thereafter. Ipi (3 mg/kg) was given every 3 wks starting on day 1 of wk 6 for up to 4 doses. Response was assessed by investigators per immune-related response criteria every 12 wks until disease progression. The primary endpoint was ORR; key secondary endpoints were OS, progression-free survival, and safety. Results: 198 pts were randomized (98 to combo; 100 to ipi). As of February 25, 2019, the median follow-up time was 40.0 mos (range: 0.2–63.7) for the combo arm. Among 98 pts who received combo, 21 (21.4%) had a best overall response of CR including 8 who converted from an initial partial response (PR), 15 (15.3%) had PR, 19 (19.4%) had stable disease, 30 (30.6%) had progressive disease, and 13 (13.2%) were unevaluable. Of 21 pts achieving CR, 17 (81%) had ECOG status of 0, 16 (76.2%) had stage IIIB-IVM1a disease, and 16 (76.2%) had no visceral metastases. Median duration of CR was not reached (range: 5.4[+]–58.2[+] mos); 19 of 21 CRs lasted more than 6 months. The baseline tumor burden was lower in pts with CR than in those with non-CR. Median OS was not reached in pts with CR (range: 25.1[+]–63.7[+] mos) and was 47.6 mos (range: 0.2[+]– 63.7[+] mos) in pts with non-CR (Log-rank P = 0.0005). The Kaplan–Meier estimated 3-year OS rate was 100.0% for patients with CR and 52.3% for those with non-CR. Conclusions: CR rate was higher with T-VEC plus ipi than with ipi alone in pts with advanced melanoma (21.4% vs. 6.0%). In the combo arm, CR was associated with prolonged OS, and pts with CR tended to have better ECOG performance status, earlier-stage disease, and lower baseline tumor burden, as compared with those with non-CR. Clinical trial information: NCT01740297.

96 Background: Evolving indications for immuno-oncology (IO) therapies in cancer pose a significant challenge to community clinicians around the practical issues that must be addressed to implement these therapies safely and effectively. The Association of Community Cancer Centers (ACCC) initiated a quality improvement (QI) research study to assess the impact of educational interventions targeting the multidisciplinary cancer care team on evidence-based integration of IO therapy. Methods: The QI study collected baseline data from 100 patients initiating IO therapy between Dec 2017-Apr 2018 at two community cancer centers on co-morbidities, immune-related adverse events (irAEs), laboratory tests, ER visits and hospitalizations, patient education, and adherence. The advisory committee analyzed this data to identify practice gaps and designed educational interventions to address these gaps. After clinicians at both centers completed the educational interventions, data was collected from 100 patients initiating IO therapy between Jan 2019-Apr2019 and compared using Fisher’s exact test. We also conducted staff surveys before and after participating in the interventions. Results: Offering ACCC-created IO wallet cards to patients was a recommended intervention but only one site adopted this. The site that used the wallet cards had a statistically significant reduction in hospitalization rates compared to the other site (38% vs 70%, p = 0.0024). Respondents to the practice surveys reported an increase in handing out patient education materials following participation in the interventions. They also reported an improved understanding of strategies to manage patients with co-morbidities, management of irAEs, patient education and engagement, interprofessional communication, and coordination with non-oncology specialists. Conclusions: Community cancer center directed educational interventions are feasible and may improve clinician understanding, comfort, and attitudes with the integration of emerging IO agents. Administering wallet cards to patients at the beginning of IO therapy may decrease the risk of hospitalization and warrants further investigation in larger studies.

9586 Background: A trial of neoadjuvant pembrolizumab (P) in combination with high dose interferon-α (HDI) in high-risk patients (pts) with locoregionally advanced melanoma (mel) has completed enrollment. Methods: Primary endpoint: safety of combination P-HDI. Pts were treated with P x 2 doses followed by definitive surgery, then x1 year. HDI was given concurrently, and both agents were per standard regimen. Tumor and blood samples were obtained at baseline and at surgery (wk 6-8), blood at 6 wks, 3,6,12 months (mos). Results: 30 pts were treated (22 male, 8 female, age 26-83). 16 had cutaneous primary, 3 mucosal, 11 unknown. At enrollment, 16 had recurrent disease, 6 received prior adjuvant therapy with ipilimumab (4) or HDI (2). 16 had AJCC 7 stage IIIB, 9 IIIC, 5 IV. 332 P cycles have been delivered (median 13), 496 doses of HDI induction (median 17), 1329 doses of HDI maintenance (median 44). HDI was dose reduced in 20 pts, discontinued in 27, P discontinued in 8. Radiologic preoperative RR was 77% (95% CI, 59-88) (6 CR, 17 PR). 20% (6) had SD and 1 had PD. All pts underwent definitive surgery. The pathologic complete response (pCR) of 26 pts was 32% (95% CI, 18-51). 6 pts recurred and 3 died. No pt with pCR has recurred. Median f/u time is 17.4 mos, median PFS/OS not reached. Most common grade (Gr) 3 toxicities: hypophosphatemia (10; 33%), fatigue (10; 33%), ↑CPK (6; 20%), ↑lipase (4; 13%). 3 Gr 4 events (↑CPK, hyperglycemia, lymphocyte count decreased). 1 suspected grade 5 event occurred 6 months after completion of therapy. PD-L1 expression at baseline did not correlate with clinical outcomes. In 8 pts with pre and post treatment tumor samples, IHC expression of PD-1, PD-L1, CD11b, CD8, Foxp3 and CD25 increased post-treatment (p < 0.05). Conclusions: Neoadjuvant P-HDI has promising clinical activity, although treatment is limited by HDI toxicity. Treatment increases the immune cell infiltrate, and outcomes do not correlate with baseline expression of PD-L1. Longer follow up and further mechanistic studies are underway. Clinical trial information: NCT02339324.

9524 Background: T-VEC is a modified oncolytic herpes virus designed as an intralesional therapy for unresectable advanced melanoma. OPTiM was a randomized, phase 3 trial that showed improved durable response rate (DRR) with T-VEC vs GM-CSF in pts with unresectable melanoma with regional or distant metastases (16.3% vs 2.1%, p < 0.001). Treatment benefit of T-VEC on DRR and overall survival (OS) was greater in stage IIIB-IVM1a vs IVM1b-IVM1c melanoma. This is the first report of PFS for T-VEC vs GM-CSF. Methods: OPTiM included pts ≥18 yrs with unresectable stage IIIB-IV melanoma; ≥1 injectable cutaneous, subcutaneous (SC), or nodal lesion; ECOG ≤1; LDH ≤1.5 ULN; ≤3 visceral metastases (excluding lung) with none > 3 cm. Pts were randomized 2:1 to receive intralesional T-VEC or SC GM-CSF. The primary endpoint was DRR (partial or complete response continuously for ≥6 mo starting within 12 mo) and reported previously. In this post hoc analysis, PFS was evaluated overall and by disease stage. Results: This analysis included 436 pts: 295 (68%) T-VEC, 141 (32%) GM-CSF; 57% men; 63 yr median age; 57% stage IIIB-IVM1a, 43% stage IVM1b-IVM1c. In the intention to treat set, T-VEC significantly improved PFS (HR: 0.68, 95% CI: 0.54, 0.85, unstratified log-rank p < 0.001). In stage IIIB-IVM1a, PFS favored the T-VEC arm vs the GM-CSF arm (HR: 0.60, 95% CI: 0.44, 0.80, unstratified log-rank p < 0.001). No treatment difference was seen in stage IVM1b-IVM1c (HR: 0.81, 95% CI: 0.57, 1.15, unstratified log-rank p = 0.199). Overall, the 12 mo PFS rate for T-VEC was 14.4% (95% CI: 10.5, 18.8) and GM -CSF was 4.6% (95% CI: 1.6, 10.2). In stage IIIB-IVM1a, the 12 mo PFS rate for T-VEC was 19.9% (95% CI: 14.0, 26.6) and GM-CSF was 3.2% (95% CI: 0.6, 9.9). In stage IVM1b-IVM1c, the 12 mo PFS rate for T-VEC was 7.4% (95% CI: 3.5, 13.2) and GM-CSF was 8.0% (95% CI: 1.9, 20.1). Conclusions: T-VEC demonstrated an improvement in PFS vs GM-CSF, driven primarily by pts with stage IIIB-IVM1a melanoma. This is consistent with previous data showing more pronounced OS benefit with T-VEC and greater efficacy with other immunotherapies in early metastatic disease. Clinical trial information: NCT00769704.

Purpose To assess pharmacodynamic effects and intrinsic and acquired resistance mechanisms of the BRAF inhibitor vemurafenib in BRAFV600-mutant melanoma, leading to an understanding of the mechanism of action of vemurafenib and ultimately to optimization of metastatic melanoma therapy. Methods In the phase II clinical study NP22657 (BRIM-2), patients received oral doses of vemurafenib (960 mg twice per day). Serial biopsies were collected to study changes in mitogen-activated protein kinase (MAPK) signaling, cell-cycle progression, and factors causing intrinsic or acquired resistance by immunohistochemistry, DNA sequencing, or somatic mutation profiling. Results Vemurafenib inhibited MAPK signaling and cell-cycle progression. An association between the decrease in extracellular signal-related kinase (ERK) phosphorylation and objective response was observed in paired biopsies (n = 22; P = .013). Low expression of phosphatase and tensin homolog showed a modest association with lower response. Baseline mutations in MEK1P124 coexisting with BRAFV600 were noted in seven of 92 samples; their presence did not preclude objective tumor responses. Acquired resistance to vemurafenib associated with reactivation of MAPK signaling as observed by elevated ERK1/2 phosphorylation levels in progressive lesions and the appearance of secondary NRASQ61 mutations or MEK1Q56P or MEK1E203K mutations. These two activating MEK1 mutations had not previously been observed in vivo in biopsies of progressive melanoma tumors. Conclusion Vemurafenib inhibits tumor proliferation and oncogenic BRAF signaling through the MAPK pathway. Acquired resistance results primarily from MAPK reactivation driven by the appearance of secondary mutations in NRAS and MEK1 in subsets of patients. The data suggest that inhibition downstream of BRAF should help to overcome acquired resistance.

Purpose Imaging with [18F]fluorodeoxyglucose (FDG) –positron emission tomography (PET) allows early recognition of a response to agents that target key driver mutations in human cancer. We aimed to determine the metabolic response rate to vemurafenib in patients with advanced BRAF-mutant melanoma. Patients and Methods Baseline and day 15 FDG-PET was evaluated in 31 patients with advanced melanoma treated in a phase I study of dose escalation of vemurafenib (PLX06-02), which included four patients treated at subtherapeutic doses and 24 patients treated at 960 mg twice a day, which is the maximum-tolerated dose of vemurafenib. Results All 27 patients treated at potentially therapeutic levels had at least a partial metabolic response, and three patients achieved a complete metabolic response. In the 27 patients, there was an 80% ± 3% reduction in the maximum standardized uptake value (SUVmax) of target lesions and an 87% ± 3% decrease in the percentage of injected dose (%ID) in all identified disease sites. There was a positive correlation between %ID in all identified disease and target-lesion SUVmax (r2 = 0.66; P < .001) that indicated a significant homogeneity of the response between lesions in individual patients. Although no relationship was found between the reduction in target lesion SUVmax and best response according to RECIST (Response Evaluation Criteria in Solid Tumors), there was a trend for patients with greater reductions in uptake of FDG to have longer progression-free survival. Conclusion FDG-PET is a useful marker of an early biologic response to vemurafenib. Little variability in PET response was found between lesions in individual patients, which suggested minimal intrapatient molecular heterogeneity. FDG-PET is a useful tool for the evaluation of the biologic impact of inhibiting mutant BRAF and may allow for the more effective development of novel agents.

3006Background: PIVOT is an ongoing, open-label, phase 1/2 study of NKTR-214 (214; CD122-biased agonist) plus PD-1 inhibitor nivolumab (N) in patients (pts) with advanced cancers (MEL, RCC, NSCLC, TNBC, and UC). 214 monotherapy increases newly proliferative CD8+ T cells in tumors and increases cell surface PD-1 and PD-L1 expression, demonstrating a potentially synergistic mechanism with anti-PD-1 therapy. Methods: In P1 dose escalation, pts received 214 (0.003, 0.006 or 0.009 mg/kg) with N (240 mg or 360 mg) administered IV as outpatient Q2W or Q3W; in P2 expansion, the RP2D of 214 (0.006 mg/kg) with N (360 mg) Q3W was administered concurrently. Response was assessed Q8W by RECIST v1.1. Matched tumor samples were evaluated for changes from baseline in immune cell populations, gene expression, and T cell receptor repertoire. Tumor baseline and on treatment PD-L1 protein expression was assessed (28-8 IHC assay). Results: As of 7FEB2018, 162 pts (P1, n = 38; P2, n = 124) were evaluable for safety. The most c...

9515Background: PD-1/L1 inhibitors have transformed MM treatment, however many patients (pts) remain refractory. Subsequent treatment options including ipi offer modest benefit (~13% respond) (Long...

TPS9601Background: Immunotherapy and targeted therapies have significantly changed the treatment landscape for advanced melanoma over the past few years. However, despite the addition of these new ...

579 Background: Prior studies combining programmed death-1 (PD-1) checkpoint inhibitors with tyrosine kinase inhibitors of the vascular endothelial growth factor (VEGF) pathway have been characterized by excess toxicity precluding further development. We hypothesized that a combination of axi, a more selective VEGF-pathway inhibitor, with pembro (anti-PD-1) would be well tolerated and yield antitumour activity in treatment-naïve pts with aRCC. Methods: This ongoing open-label phase Ib study of axi/pembro comprised a dose-finding phase to determine the maximum tolerated dose and dose expansion phase. Axi 5 mg was administered orally twice daily with pembro 2 mg/kg administered intravenously every 3 weeks. Tumors were assessed, using RECIST v1.1, at baseline, week 12, and every 6 weeks thereafter. The primary endpoint was dose-limiting toxicity (DLT) during the first 2 cycles (6 weeks), with secondary endpoints evaluating safety, objective response rate (ORR), progression-free survival (PFS), and overall survival (OS). Results: Between 23 Sept 2014 and 13 Oct 2015, 52 treatment-naïve pts with aRCC were enrolled. No unexpected toxicities were observed. Three DLTs were reported among the 11 pts treated in the dose-finding phase: transient ischemic attack (n = 1) and < 75% of planned axi dosage administered due to treatment-related toxicity (n = 2). At cutoff date (March 30, 2017), 25 pts were receiving study treatment. Most common (≥10%) grade ≥3 all-causality AEs included hypertension (23%), diarrhoea (10%) and fatigue (10%). Most common ( > 10%) potentially immune-related AEs included diarrhoea (29%), increased alanine aminotransferase (17%), or aspartate aminotransferase (13%), hypothyroidism (13%), and fatigue (12%). ORR was 73.1% (95% confidence intervals [CIs], 59.0–84.4). Median (95% CI) PFS was 20.9 (15.4–not evaluable) months. OS data were not mature at minimum follow-up period of 17.6 months, with 6 treatment-unrelated deaths reported. Conclusions: The combination axi/pembro is tolerable and exhibits promising antitumour activity in treatment-naïve pts with aRCC. A randomized phase 3 trial comparing the combination to sunitinib monotherapy is underway. Clinical trial information: NCT02133742.

181 Background: Neoadjuvant pembrolizumab at 200 mg in combination with high dose IFNα2b (HDI) for locally/regionally advanced or recurrent melanoma may improve the clinical outcomes of these high risk patients (pts), and provide access to blood and tumor pre/post pembro-HDI to illuminate the host effector and suppressor immune mechanisms. Methods: Pts were treated with pembro 200 mg IV every 3 weeks (wk) x 2 doses followed by definitive surgery, then every 3 wks for up to one year. HDI (20 MU/m²/d IV x 5 days (d)/wk for 4 wks then 10 MU/m²/d SC every other d TIW for 48 wks) was given concurrently. Tumor samples were obtained at baseline and at definitive surgery (wk 6-8) and serum/PBMC at baseline, 6 wks, 3, 6, 12 months (mo). Results: Twenty evaluable pts (14 male, 6 female, 14 cutaneous primary, 4 unknown, 3 mucosal), age 29-82 were treated. 5 had Stage IIIB (N1b, N2b, M2c), 11 IIIC (N3) and 4 IV (M1a, M1b) melanoma. Over 230 cycles have been delivered to date (median 14). Worst toxicities included grade (Gr) 3: fatigue (8; 40%), ↑CPK (5; 25%), hypophosphatemia (5; 25%), ↑lipase (3; 15%), lymphopenia (3; 15%), hypertension (2; 10%), diarrhea/colitis (1; 5%), arthralgia (1, 5%), syncope (1, 5%), hyponatremia (1, 5%), neutropenia (1; 5%), anemia (1, 5.00%) nausea (2, 10%), flu like symptoms (1, 5%). There were 3 Gr 4 events (CPK, hyperglycemia, lymphopenia). One suspected grade 5 event occurred 6 months after completion of therapy with autopsy evidence of pneumonia and myocarditis. Among 20 evaluable pts, 4 relapsed and 1 died. Median follow-up for pts who have not relapsed is 11 months. The radiologic preoperative response rate (WHO; unconfirmed) was 65%. The pathologic complete response rate (no viable tumor on histologic assessment) was 35%. Conclusions: Neoadjuvant pembro-HDI exhibited promising clinical activity. Longer follow up is underway in order to define the long term benefits and risks. Clinical trial information: NCT02339324.

182 Background: The association between tumor mutational profiles and immune signatures has not been well-characterized. Methods: 306 melanoma samples were tested by NGS using a comprehensive cancer panel for mutational status and an immune response panel which interrogates the expression profile of 54 validated immune-related genes. The ranking of gene expression, mutational burden and 7 immune phenotypes was compared to a reference population. 38% cases were positive for activating BRAF mutations, 12% for RAS, and 6% for NF1. The remaining 44% were considered triple wild type. Principal component analysis (PCA) followed by hierarchical clustering was performed to determine association of BRAF/RAS/NF1 mutations and triple wild type with immune phenotypes, mutational burden and gene expression as measured by the NGS panels. Results: PCA showed that the first and second dimension explain 86% of the variation in the mutation profiles of the 306 melanomas. The first principal component highly correlated with BRAF positive status (pval < 0.001), the second highly correlated with RAS positive status (pval < 0.001), and the third principal component, although not informative, highly correlated with NF1 status (pval < 0.001) and Mutation Burden (pval < 0.001). Hierarchical clustering of the samples resulted in 4 distinct clusters: RAS positive, BRAF Positive, NF1 positive and triple wild type. The RAS positive cluster demonstrated significantly lower expression of ICOSLG, ICOS, CD4, C10orf54, CD40 and CD244 genes. Similarly, the BRAF positive cluster under-expresses immune escape and proinflammatory immune phenotypes, but over-expressed OX40L. The NF1 positive cluster had significantly higher mutational burden than other clusters. On the contrary, the triple wild type cluster over-expressed 6 out of 7 immune phenotypes. Conclusions: BRAF/RAS/NF1 mutation status are immunophenotypically distinct and do not associate with a typical immune phenotype in the tumor microenvironment. Triple wild type samples present with an overall activated immune phenotype, representative of an inflamed tumor. Additional studies are necessary to include additional activating or loss of function mutations to expand these findings.

23 Background: Associations between presence and density of effector T-cells (CD8+) and response to checkpoint inhibitors (CPIs) has been established for protein biomarkers using immunohistochemistry but less work has been done to characterize this relationship through gene expression. Methods: We collected clinical response data (RECIST v1.1) for 184 patients who had been treated with CPIs across tumor types with FDA indications. We tested formalin-fixed paraffin embedded (FFPE) samples by NGS with a comprehensive immune response panel which interrogates the gene expression profile of 54 validated immune-related genes. Ranked gene expression was compared to a reference population. 85/184 (46%) cases were considered “responders” after six months, and 66/184 cases (36%) were considered responders after twelve months on treatment. We hypothesized that patients with in the bottom quartile of CD8 expression, as measured by the rank of the sum of normalized CD8A and CD8B transcripts compared to a reference population, would be unlikely to respond to checkpoint therapy (immune deserts), and that “hot” tumor environments (TME) with the highest quartile of expression would be most likely to respond. Results: After six months of therapy, 13/40 (32.5%) patients with immune desert tumors responded to therapy, whereas 39/82 patients (47.6%) in the middle 50% of expression responded, and 33/62 (53.2%) of patients with “hot” TME responded to treatment. The two-tailed p-value of the null hypothesis, that TME status does not correlate with response, was 0.018 and could be rejected. After twelve months of observation, 9/40 (22.5%) immune desert patients were considered “responders”. 28/82 (34.2%) of the middle 50% of expression were classified as responders, and 29/62 (46.8%) of top quartile samples came from responders. The two-tailed p-value of the null hypothesis was 0.005 and could be rejected. Conclusions: Gene expression of CD8 as measured by RNA-seq from FFPE samples can be used to compare these samples versus a reference population to predict an increase or decrease in likelihood of response to CPIs. Patients in the lowest quartile of CD8 expression were the least likely to respond to these promising therapies.

146 Background: The association between neoplasm mutational and immune profiles has not been well-characterized. Methods: We collected 26 lung cancer formalin-fixed paraffin embedded (FFPE) samples which had been tested with a comprehensive mutation profile to detect clinically actionable mutations, and a comprehensive immune gene expression profile, which interrogates PD-L1 immunohistochemistry (IHC), PD-L1/2 copy number, CD3/CD8 IHC, microsatellite instability status, mutational burden, and the expression profile of 54 immune-related genes. The ranking of gene expression and 7 immune phenotypes was compared to a reference population. Six cases were positive for an activating KRAS mutation and 2 cases were positive for an activating EGFR mutation. Principal component analysis was performed to determine the association of EGFR/KRAS mutations with the measured immune landscape. Results: The proinflammatory immune phenotype was significantly correlated with KRAS mutation positive samples (first principal component, R squared = 0.53, p < 0.05). Similarly, CD38 expression was correlated with KRAS mutation (R squared = 0.47, p < 0.05). CD137, KLRD1, and DDX58 expression was significantly correlated with EGFR positive samples (second principal component, R squared = 0.47, 0.37, 0.35 respectively, p < 0.05 in all cases). Unsupervised hierarchical clustering of the samples resulted in three distinct clusters, EGFR positive, KRAS positive, and EGFR negative/KRAS negative. In the KRAS positive cluster, high proinflammatory immune phenotype, VISTA moderate expression, presence of CD3/CD8 tumor infiltrating lymphocytes (TILs), and low KLRD1 were overrepresented (p < 0.05), while low VISTA and proinflammatory moderate immune phenotype were significantly underrepresented (p < 0.05). In the EGFR positive cluster DDX58 high, very low TILs, and very low CD8 were significantly (p < 0.05) overrepresented. Conclusions: KRAS mutation positivity is significantly associated with a proinflammatrory immune phenotype and CD3/CD8 infiltration. KRAS positive, EGFR positive, and KRAS/EGFR negative clusters are immunophenotypically distinct. A higher number of specimens is necessary to verify and expand these findings.

TPS219 Background: Talimogene laherparepvec, a modified herpes virus agent, induces a response in 65% of injected melanoma tumors. The combination of talimogene laherparepvec with ipilimumab or pembrolizumab appears promising in clinical trials of advanced melanoma. Talimogene laherparepvec-based therapy may be effective in other cancers of the skin and lymph nodes that are anatomically accessible for intratumoral injection. Methods: This phase II study will evaluate intratumoral talimogene laherparepvec monotherapy in 4 parallel disease cohorts: 1) Refractory T cell and NK cell lymphomas including cutaneous T cell lymphoma, 2) Merkel cell carcinoma 3) Cutaneous squamous cell carcinoma and 4) Other advanced/refractory non-melanoma skin cancers. Lymphoma patients must be refractory to or intolerant of all standard life-prolonging therapies. Skin cancer patients must be advanced/unresectable or refractory to one or more treatments including surgery, radiation therapy, or medical therapy. Prior PD-1-directed therapy is allowed. If an objective response is not achieved by Week 12, the PD-1 blocking antibody nivolumab will be added. The primary endpoint is the response rate with talimogene laherparepvec and secondary endpoints include response rate with the combination and overall survival. Using a two-stage design, if 1 or more response is observed in the first 9 patients in each parallel cohort, 8 additional patients will be accrued for a total sample size of 36 to 68 patients across the 4 disease cohorts. Tumor biopsies of injected lesions are mandatory at baseline and Week 6, and optional at Week 16 and the time of progression. Optional biopsies of non-injected lesions (when applicable) at Week 6 and 16 will be analyzed to identify biomarkers of systemic immunity. Tumor tissue and/or blood will be assayed for PD-L1 expression, RNA profiling, immune cell profiling, HVEM, NECTIN 1/2, IDO, tryptophan and L-kynurenine, mutational load, TIL TCR clonality, and prior exposure to herpes simplex type 1 virus and Merkel cell polyomavirus. Clinical trial information: NCT02978625.

190 Background: CD8 positive tumor infiltrating lymphocytes (TILS) are highly associated with immune response and prognosis, and are also under investigation as a marker of response to checkpoint inhibitors. Given lack of predictive biomarkers for ipilimumab, growing number of trials for new indications for combination ipilimumab + nivolumab, and evidence to support therapeutic target overexpression as markers of response, we examined the role of CTLA-4 expression and TILS in response to ipilimumab and combination ipilimumab + nivolumab in melanoma. Methods: Formalin-fixed paraffin embedded melanoma samples taken prior to treatment by ipilimumab (n = 36) or combination ipilimumab + nivolumab (n = 10) were evaluated by a comprehensive immune gene expression profile to establish the relationship between CTLA-4 and CD8 and therapeutic response (RECIST v1.1). Results: Increased CTLA-4 expression was moderately associated with increased TILS (r2= .41, p = .004). This was observed in the monotherapy group (r2= .38, p = .02), and was higher in the smaller combination therapy group, though not statistically significant (r2= .59, p = .06). Higher levels of TILS were observed in responders who achieved clinical benefit from either regimen within 6 months (n = 20). No significant difference was observed between responders (M = 57.1, SD = 30.2) and nonresponders (M = 48.6, SD = 32.9); t(44) = -.895, p = .376. Lower levels of CTLA-4 were observed in responders who achieved clinical benefit from either regimen within 6 months. No significant difference was observed between responders (M = 54, SD = 35) and nonresponders (M = 38.7, SD = 26.8); t(44) = 1.70, p = .09. The ratio of TILS to CTLA-4 expression was higher in responders who achieved clinical benefit within 6 months (n = 20).No significant difference was observed between responders (M = 5.2, SD = 14.0) and nonresponders (M = 1.4, SD = 2.7); t(41) = -1.2, p = .212. Conclusions: While not statistically significant, CTLA-4 expression in melanoma patients treated with either ipilimumab or combination ipilimumab + nivolumab was lower in responders compared to nonresponders. This analysis does not support the concept that over-expression of CTLA-4 is a biomarker of response to anti-CTLA-4 therapy.

Purpose This phase II study evaluated the efficacy and safety of sorafenib plus dacarbazine in patients with advanced melanoma. Patients and Methods This randomized, double-blind, placebo-controlled, multicenter study enrolled chemotherapy-naïve patients with stage III (unresectable) or IV melanoma. A total of 101 patients received placebo plus dacarbazine (n = 50) or sorafenib plus dacarbazine (n = 51). On day 1 of a 21-day cycle, patients received intravenous dacarbazine 1,000 mg/m2 for a maximum of 16 cycles. Oral sorafenib 400 mg or placebo was administered twice a day continuously. The primary end point was progression-free survival (PFS) by independent assessment. Secondary and tertiary end points included time to progression (TTP), response rate, and overall survival (OS). Results Median PFS in the sorafenib plus dacarbazine arm was 21.1 weeks versus 11.7 weeks in the placebo plus dacarbazine arm (hazard ratio [HR], 0.665; P = .068). There were statistically significant improvements in PFS rates at 6 and 9 months, and in TTP (median, 21.1 v 11.7 weeks; HR, 0.619) in favor of the sorafenib plus dacarbazine arm. No difference in OS was observed (median, 51.3 v 45.6 weeks in the placebo plus dacarbazine and sorafenib plus dacarbazine arms, respectively; HR, 1.022). The regimen was well tolerated and had a manageable toxicity profile. Conclusion Sorafenib plus dacarbazine was well tolerated in patients with advanced melanoma and yielded an encouraging improvement in PFS. Based on these findings, additional studies with the combination are warranted in this patient population.

2004 Background: Recurrent malignant gliomas (MG) are a universally fatal disease in desperate need of better therapies. Pleiomorphic xanthoastrocytomas (PXA) and juvenile pilocytic astrocytomas (JPA) typically have better outcomes, although when recurrent, also represent an aggressive disease with no proven effective chemotherapy. BRAFV600 alterations have been identified in a substantial proportion of gliomas, including glioblastoma (GBM), astrocytoma, PXA, and JPA. The phase 2, open-label, histology-independent VE-BASKET study of vemurafenib, a selective BRAFV600 kinase inhibitor, in patients with BRAF mutation-positive non-melanoma tumors, included those with gliomas in the ‘all-others’ cohort. We now report final data for patients with recurrent gliomas. Methods: Patients received vemurafenib (960 mg bid) until disease progression or unacceptable toxicity. The primary endpoint was investigator-assessed response rate; secondary endpoints included clinical benefit rate (confirmed complete or partial response or stable disease lasting ≥6 months), progression-free survival (PFS), overall survival (OS), and toxicity. ClinicalTrials.gov NCT01524978. Results: 24 patients (median age 32 years; 18 female, 6 male) with glioma were treated, including mg (n = 11; 6 GBM and 5 anaplastic astrocytoma [AA]), PXA (n = 7), anaplastic ganglioglioma (AG, n = 3), JPA (n = 2), and unknown (n = 1). In patients with mg (n = 11), best response included PR (n = 1; AA), SD (n = 5), PD (n = 3), and unknown (n = 2). Two patients with mg had durable SD lasting 12.9 months (GBM) and 14.9 months (AA). In patients with PXA (n = 7), best response included CR (n = 1), PR (n = 2), SD (n = 3), and PD (n = 1). Additionally, 1 patient with JPA and 1 with AG achieved a PR. The most frequent AEs included arthralgia (67%), melanocytic nevus (38%), palmar-plantar erythrodysesthesia (38%), photosensitivity reaction (38%) and alopecia (33%). Conclusions: Vemurafenib demonstrated activity in patients with BRAFV600 mutant glioma. The safety profile was similar to that seen in previous melanoma studies. Survival data will be presented. Clinical trial information: NCT01524978.

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]

9509 Background: T is a HSV-1-based oncolytic virus designed to selectively replicate in tumors and produce GM-CSF to stimulate antitumor immune responses. I is an anti-CTLA-4 Ab that blocks inhibition of activated T cells. This is the first randomized study to evaluate the addition of an oncolytic virus to a checkpoint inhibitor. Methods: The 1o endpoint was ORR by immune-related response criteria. Key 2o endpoints: duration of response, disease control rate (DCR), PFS, OS, and safety. Prior treatment was allowed but not required. Pts had unresected stage IIIB-IV melanoma with measurable/injectable tumor(s) and no evidence of immunosuppression. T was given at approved dosing until no injectable tumors, disease progression (PD), or intolerance. I was started at w6 in T+I and at w1 in I at 3 mg/kg IV q3w x 4. Primary analysis occurred 6 m after last pt enrolled. Results: 198 pts were randomized: 98 T+I; 100 I. Characteristics were similar: 54% stage IIIB-IVM1a, 46% IVM1b/c. Median follow up time was 68 w (T+I) and 58 w (I). ORR was 38.8% (T+I) and 18.0% I, P = 0.002, Odds ratio (OR) 2.9. 89% T+I and 83% I pts remain in response. Unconfirmed visceral lesion response was 35.5% T+I vs 13.6% I. OS is immature. Of 190 pts (safety set: 95 T+I, 95 I), most common adverse events (AEs) for T+I, I (%) were fatigue (59, 42), chills (53, 3), and diarrhea (42, 35). 28% T+I and 18% I pts had gr ≥3 tx-related AE. There were 3 deaths (all unrelated) in T+I: 1 myocardial infarction and 2 PD. Conclusions: The study met the 1o endpoint. ORR was significantly higher for T+I vs I; responses were not limited to injected lesions. Toxicity of T+I combination was tolerable with no unexpected AEs. Clinical trial information: NCT01740297. [Table: see text]

9074 Background: BRAFV600 mutations occur in 1–2% of pts with NSCLC. We previously reported the efficacy of vemurafenib, a selective BRAFV600 inhibitor, in BRAF mutation-positive non-melanoma tumors (VE-BASKET study). We now present final data for the expanded NSCLC cohort. Methods: This open-label, histology-independent, phase 2 study included 6 prespecified cohorts (including NSCLC) plus one ‘all-others’ cohort. Pts received vemurafenib (960 mg bid) until disease progression or unacceptable toxicity. The primary endpoint was objective response rate (RECIST v1.1). Secondary endpoints included best overall response rate, duration of response (DoR), progression-free survival (PFS), and overall survival (OS). Because the pre-specified clinical benefit endpoint was met in the initial NSCLC cohort, the cohort was expanded. ClinicalTrials.gov identifier NCT01524978. Results: Database lock was 12 Jan 2017. Of 208 pts enrolled at 25 centers worldwide, 62 pts had NSCLC: median age 65 years; 56% male; 13% had no prior systemic therapy; 50% had ≥2 prior therapies. Responses were seen in previously treated and untreated pts (Table). The most common all-grade adverse event (AE) was nausea (40%); grade 3–5 AEs included keratoacanthoma (15%) and squamous cell carcinoma of the skin (15%). Six pts discontinued vemurafenib due to AEs; two had non-treatment-related fatal AEs. Conclusions: Vemurafenib showed evidence of encouraging efficacy in pts with NSCLC with BRAFV600 mutation, with prolonged PFS in previously untreated pts; median OS was not estimable due to ongoing responses. The safety profile of vemurafenib was similar to that seen in melanoma studies. Our results suggest a role for BRAF inhibition in NSCLC with BRAF mutations. Clinical trial information: NCT01524978. [Table: see text]

9566 Background: Ipilimumab-related colitis has been well described, but the clinical presentation of colitis related to MONO or COMBO therapy has not. We aimed to characterize clinical features that define this serious adverse event. Methods: This retrospective study included melanoma pts with colitis screened from 6 academic centers treated with either MONO or COMBO therapy. Clinically relevant colitis was defined as diarrhea/colitis symptoms requiring systemic steroids. The onset, management, and outcomes related to colitis were summarized. Results: We screened 866 pts and identified 72 with clinically relevant colitis. For the MONO cohort, the incidence was 3.5% (23/657) and 23.4% (49/209) in the COMBO cohort. MONO-colitis occurred at a median 33 weeks (wks) into therapy, while median onset was 8 wks with COMBO therapy. One pt had grade 5 colitis from COMBO therapy. Despite the use of systemic steroids, COMBO-colitis needed more infliximab therapy (38.8% vs 26.1%). The median prednisone equivalent dose was higher for COMBO therapy (1.5 vs 1 mg/kg), and the median taper was shorter for MONO-colitis (4 vs 6 wks). Steroid dose-escalation for worsening symptoms during taper was more common with COMBO-colitis (42.9% vs 17.3%). Relapse was similar between cohorts (MONO: 26.1%, COMBO: 20.4%). Relapses occurred more frequently in COMBO therapy with tapers shorter than the median (38.1% vs 25.0%), and more frequently in MONO therapy with steroid doses lower than the median (60% vs 21.7%). MONO-colitis pts (17.4%) were less likely than COMBO-colitis pts (46.9%) to be restarted on PD-1 therapy. When restarted, only 13% with COMBO therapy relapsed as compared to 50% with MONO therapy. Objective response rates for MONO and COMBO cohorts were 72.7% and 56.1%, respectively. Conclusions: Colitis occurred with a much higher incidence in COMBO therapy. MONO-colitis was associated with a milder course with later onset, shorter duration and lower dose of steroids, fewer dose-escalations, and need for infliximab as compared to COMBO therapy. Relapse of colitis was generally associated with shorter steroid tapers for COMBO therapy and lower steroid doses for MONO therapy.

TPS9598Background: Talimogene laherparepvec, an oncolytic viral immunotherapy, was designed to selectively replicate in tumors resulting in lytic cell death, antigen release, and production of GM-C...

5581Background: There are currently no treatment options for pts with endometrial cancer who progress on chemotherapy. Pembrolizumab is an anti–PD-1 antibody that blocks interaction between PD-1 and its ligands, PD-L1/PD-L2. The safety and efficacy of pembrolizumab were evaluated in advanced solid tumors in the KEYNOTE-028 study (NCT02054806). Preliminary results from the endometrial carcinoma cohort are presented. Methods: Key inclusion criteria were advanced endometrial carcinoma (excluded sarcomas, mesenchymal tumors), failure of prior systemic therapy, ECOG PS 0-1, and PD-L1 expression in ≥ 1% of tumor or stroma cells by IHC. Pembrolizumab 10 mg/kg every 2 wk was given for up to 24 mo or until confirmed progression, intolerable toxicity, death, or consent withdrawal. Response was assessed every 8 wk for the first 6 mo and every 12 wk thereafter. The primary end point was ORR per RECIST v1.1 by investigator assessment. Results: In the 24 pts enrolled, median age was 67.0 y; 66.7% had an ECOG PS of 1; 6...

e14539Background: Anti-PD-1 (aPD1) is increasingly used in various advanced malignancies. Patients (pts) with baseline organ dysfunction are largely excluded from clinical trials. Therefore it is u...

9513Background: In KEYNOTE-006 (NCT01866319), pembro (MK-3475) provided superior OS and PFS and a lower grade 3-5 treatment-related AE rate over ipi in patients (pts) with advanced melanoma and ≤ 1 prior therapy. We assessed the impact of PD-L1 expression and prior therapy on outcomes in KEYNOTE-006. Methods: Pts were randomized to pembro 10 mg/kg Q2W or Q3W or ipi 3 mg/kg Q3W. Pembro was given for 24 mo or until progression, intolerable toxicity, or investigator decision. Ipi was given for 4 cycles or until progression, intolerable toxicity, or investigator decision. PD-L1 was assessed by IHC using the 22C3 antibody; positivity was defined as ≥ 1% staining in tumor and adjacent immune cells. Response was assessed at wk 12, Q6W until wk 48, then Q12W. Survival follow-up was every 12 wk. Primary end points were OS and PFS (RECIST v1.1, central review). Data cutoff date was Mar 3, 2015. Pembro arms were pooled for this analysis. Results: Of the 834 pts enrolled, 80% were PD-L1+, 18% were PD-L1–, and 2% were...

9568Background: T-VEC is a herpes simplex virus (HSV)-1 -based oncolytic immunotherapy designed to selectively replicate in tumors, produce GM-CSF and stimulate antitumor immune responses in melanoma. T-VEC significantly improved durable response rate vs GM-CSF in stage IIIB-IV melanoma patients (pts) with injectable tumors. Pembro inhibits programmed cell death protein 1 and improves survival in advanced melanoma. The combination may further improve clinical benefit. Here we report phase 1b efficacy, safety and biomarker data from a phase 1b/3 study of T-VEC+pembro in unresectable stage IIIB-IV melanoma (NCT02263508) with all pts having started on T-VEC+pembro ≥ 6 mo prior. Methods: Key inclusion criteria: unresectable stage IIIB-IV melanoma, injectable lesions; no prior systemic tx; and ECOG PS 0-1. T-VEC: ≤ 4 mL in (sub)cutaneous/nodal lesions, 106 PFU/mL d1, 108PFU/mL d22 then Q2W; pembro: IV, 200 mg d36 then Q2W. Tx until first occurrence of: complete response (CR); no injectable tumors (for T-VEC); ...

9510Background: The BRIM7 study (ClinicalTrials.gov ID, NCT01271803) evaluated the safety and preliminary efficacy of C+V (Ribas A et al. Lancet Oncol. 2014;15:954-965.); a subsequent randomized ph...

e21023Background: The advent of agents blocking programmed death 1/ligand (PD-1/PD-L1) has transformed the treatment of melanoma and other malignancies. A recent study suggested that suppression of...

e16104Background: Sunitinib is used widely as initial therapy for metastatic renal cell carcinoma (mRCC). However, sunitinib is associated with a risk of cardiovascular (CV) toxicities, including h...

9516Background: Antibodies against PD-1 resulted in a paradigm shift in the management of melanoma. Nevertheless, melanoma is a heterogeneous disease: compared to cutaneous melanoma, mucosal melano...

105Background: Agents blocking programmed death-1/ligand (aPD1) induce durable responses in many melanoma patients (pts). Greater numbers of somatic mutations have been linked to high aPD1 response rates (RR) in other cancers. We assessed whether number and/or type of mutations (mut) using HC NGS correlated with outcomes to aPD1 in melanoma. Methods: HC NGS on 236-315 genes was performed on archival samples from pts who received aPD1 (comprising ~1.25 megabases [MB]). A novel algorithm extrapolated genomic mutational load (ML) from this panel. Intratumoral T cell clonal expansion was determined by T cell receptor (TCR) sequencing. ML and TCR clonality were correlated with with aPD1 outcomes. Results: Responders to aPD1 had higher ML compared to non-responders in discovery (median 45.6 vs. 3.9 mut/MB; p=0.003, n=32), and validation cohorts (37.1 vs. 12.8 mut/MB; p=0.002, n=33). RR was superior in high ML pts compared to intermediate/low (Table) as was progression-free survival (PFS) (median not reached [MN...

9063 Background: T-VEC is an HSV-derived oncolytic immunotherapy designed to induce systemic antitumor immunity. In a phase 3 melanoma study, T-VEC monotherapy significantly improved durable respon...

3068 Background: Optimization of antibody dosing in oncology drug development is an area of growing interest. We have previously demonstrated that the dose and schedule of pembrolizumab does not co...

9019 Background: Ipilimumab (Ipi) is a cornerstone of metastatic melanoma therapeutics. Since Ipi toxicities are largely immune-related, clinicians may withhold therapy in patients (pts) with pre-e...

e20045 Background: Elevated lactate dehydrogenase (LDH) is a known negative prognostic marker in patients (pts) with metastatic melanoma (MM) and may predict lack of response to anti-PD-1/PD-L1 age...

9036 Background: This Phase I—II study evaluated the safety and efficacy of the combination of dabrafenib and trametinib (the combination) compared with dabrafenib alone (monotherapy) in patients (...

3012 Background: Pembro is an anti–PD-1 antibody approved for treating advanced MEL that progressed following IPI and, if BRAFV600 mutant, a BRAF inhibitor. In KEYNOTE-002 (NCT01704287), pembro dos...

TPS9081 Background: T-VEC is a herpes simplex virus-1-based oncolytic immunotherapy designed to preferentially replicate in tumors, produce GM-CSF and stimulate an anti-tumor immune response. OPTiM...

4507 Background: Limited evidence exists to guide therapeutic decisions in patients (pts) with metastatic non-clear cell RCC (NC-RCC). Methods: ASPEN was an international, randomized trial of pts w...