A Phase Ib Trial of Personalized Neoantigen Therapy Plus Anti-PD-1 in Patients with Advanced Melanoma, Non-small Cell Lung Cancer, or Bladder Cancer

Neoantigens arise from mutations in cancer cells and are important targets of T cell-mediated anti-tumor immunity. Here, we report the first open-label, phase Ib clinical trial of a personalized neoantigen-based vaccine, NEO-PV-01, in combination with PD-1 blockade in patients with advanced melanoma, non-small cell lung cancer, or bladder cancer. This analysis of 82 patients demonstrated that the regimen was safe, with no treatment-related serious adverse events observed. De novo neoantigen-specific CD4⁺ and CD8⁺ T cell responses were observed post-vaccination in all of the patients. The vaccine-induced T cells had a cytotoxic phenotype and were capable of trafficking to the tumor and mediating cell killing. In addition, epitope spread to neoantigens not included in the vaccine was detected post-vaccination. These data support the safety and immunogenicity of this regimen in patients with advanced solid tumors (Clinicaltrials.gov: NCT02897765).

Conserved Interferon-γ Signaling Drives Clinical Response to Immune Checkpoint Blockade Therapy in Melanoma

We analyze the transcriptome of baseline and on-therapy tumor biopsies from 101 patients with advanced melanoma treated with nivolumab (anti-PD-1) alone or combined with ipilimumab (anti-CTLA-4). We find that T cell infiltration and interferon-γ (IFN-γ) signaling signatures correspond most highly with clinical response to therapy, with a reciprocal decrease in cell-cycle and WNT signaling pathways in responding biopsies. We model the interaction in 58 human cell lines, where IFN-γ in vitro exposure leads to a conserved transcriptome response unless cells have IFN-γ receptor alterations. This conserved IFN-γ transcriptome response in melanoma cells serves to amplify the antitumor immune response. Therefore, the magnitude of the antitumor T cell response and the corresponding downstream IFN-γ signaling are the main drivers of clinical response or resistance to immune checkpoint blockade therapy.

Abstract CT250: A Phase 1a/1b, open-label first-in-human study of the safety, tolerability, and feasibility of gene-edited autologous NeoTCR-T cells (NeoTCR-P1) administered to patients with locally advanced or metastatic solid tumors

Introduction: Neoepitopes (neoE) derived from private tumor-exclusive mutations represent compelling targets for personalized TCR-T cell therapy. An ultra-sensitive and high-throughput process was developed to capture tumor mutation-targeted CD8 T cells from patient blood. NeoTCRs cloned from the captured CD8 T cells, when engineered into fresh CD8 and CD4 T cells, effected killing of patients' autologous tumor cells in vitro. These observations have been leveraged for the development of a fully personalized adoptive T cell therapy (NeoTCR-P1). A Phase 1 clinical trial testing NeoTCR-P1 in subjects with solid tumors is ongoing (NCT03970382). Study Design: During the initial trial phase, escalating doses of NeoTCR-P1 T cells administered without and with IL-2 in the regimen, and following conditioning chemotherapy, will be evaluated in subjects with advanced or metastatic solid tumors (melanoma, urothelial cancer, colorectal cancer, ovarian cancer, HR+ breast cancer, and prostate cancer). The objective of the Phase 1a study is to establish a recommended Phase 2 dose. Primary endpoints include the incidence and nature of DLTs and overall process feasibility. The proliferation, persistence, and trafficking of NeoTCR-T cells will be characterized. In the expansion trial phase, preliminary anti-tumor activity of NeoTCR-P1 will be assessed in selected tumors. The combination of NeoTCR-P1 dosing plus nivolumab will be tested in a Phase 1b study. Conclusion: This is the first clinical study of an autologous, fully personalized adoptive T cell therapy directed against private tumor-exclusive mutations, generated without using recombinant viral vectors.

Citation Format: Mihaela Cristea, Bartosz Chmielowski, Roel Funke, Todd Stallings-Schmitt, Mitch Denker, Mark Frohlich, Alex Franzusoff, Mehrdad Abedi, Samuel Ejadi. A Phase 1a/1b, open-label first-in-human study of the safety, tolerability, and feasibility of gene-edited autologous NeoTCR-T cells (NeoTCR-P1) administered to patients with locally advanced or metastatic solid tumors [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 CT250.

Abstract CT031: COM701 demonstrates preliminary antitumor activity as monotherapy and in combination with nivolumab in patients with advanced solid tumors

Introduction: COM701 is a novel first-in-class Immune checkpoint inhibitor (ICI) that binds with high affinity to poliovirus receptor related immunoglobulin domain containing (PVRIG) blocking its interaction with its ligand, PVRL2 and regulating the activity of T/NK cells through the DNAM/TIGIT axis. In preclinical experiments inhibition of PVRIG alone and in combination with anti-PD1 and/or TIGIT leads to tumor growth inhibition and activation of T-cells in the microenvironment generating an antitumor response. Methods: A total of 28 pts (Arm A/B 16/12) with a variety of cancer types were enrolled. Hybrid accelerated (1st 4 dose cohorts in Arm A) and 3+3 study design (cohorts 5-8 in Arm A and all cohorts in Arm B). Patients with performance status ECOG 0-1 and advanced or metastatic solid tumors who failed standard of care tx were eligible. Prior ICIs were permissible. In Arm A pts received COM701 monotherapy 0.01, 0.03, 0.1, 0.3, 1, 3, 10mg/kg (all IV Q 3 weeks (wks)) and 20 mg/kg (IV Q 4 wks). In Arm B, pts received COM701 at 0.3, 1 or 3mg/kg plus nivolumab 360mg IV q3 wks (3 pts/dose cohort) and 3 pts received 10mg/kg plus nivolumab 480mg IV q4 wks. Treatment emergent adverse events (TEAEs) were reported per CTCAE v4.03 and responses per RECIST v1.1. Dose-limiting toxicities (DLTs) were evaluated within a 21-day or 28-day window (for 3- or 4-wks dosing schedule respectively). Data cutoff date was January 23, 2020. Results: The median number of prior anticancer therapies were: Arm A, 7 (range 2-15), Arm B, 5 (range 2-9). No DLTs have been reported in any of the dose cohorts. Tx was well tolerated with no subjects discontinuing tx due to toxicity, the most frequent TEAEs in Arm A were fatigue (46%), nausea (31%) and anxiety (23%) - all G1-2. In Arm B ≥4 pts - anemia, lower extremity edema, rash and fatigue the majority being grade 1-2 (88%). In Arms A+B: partial response (PR) + stable disease (SD) was 57% (16/28). Of note: Arm A (COM701 20mg/kg IV q4 wks): confirmed PR in a pt with primary peritoneal cancer ongoing on tx > 15 weeks. Arm B: unconfirmed PR in a pt with MSS-CRC on COM701 0.3mg/kg plus nivolumab 360mg IV q3 wks, ongoing on tx >34 wks). Overall 11/28 pts remain on study tx including 3 pts who have not reached 1st imaging assessment. Conclusion: COM701 is well tolerated as monotherapy and in combination with nivolumab in a variety of heavily pretreated pts with advanced or metastatic solid tumors. COM701 demonstrates encouraging preliminary antitumor activity with objective responses as monotherapy and in combination with nivolumab in hard to treat tumor types (primary peritoneal and MSS-CRC).

Citation Format: Ryan Sullivan, Drew Rasco, Emerson Lim, Manish Sharma, Dale Shepard, Amita Patnaik, Erika Hamilton, Gini Fleming, Kyri Papadopoulos, Adam ElNaggar, Adeboye Henry Adewoye, Bartosz Chmielowski, Ecaterina Dumbrava, Dan Vaena. COM701 demonstrates preliminary antitumor activity as monotherapy and in combination with nivolumab in patients with advanced solid tumors [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 CT031.

Abstract LB-133: Correlative analysis of pharmacokinetics and pharmacodynamics of RGX-104, a first-in-class Liver-X-Receptor (LXR) agonist, and clinical outcomes in patients with advanced solid tumors

RGX-104, a first-in-class small-molecule LXR agonist modulates innate immunity and cancer progression via transcriptional activation of ApoE. ApoE protein suppresses tumor cell invasion and angiogenesis, and also depletes circulating and tumoral myeloid derived suppressor cells (MDSC), leading to T cell activation.A multivariate approach was used to address pharmacokinetic (PK) and pharmacodynamic relationships of RGX-104 in a phase 1 dose escalation study in patients with relapsed/refractory solid tumors. The study entailed multiple escalation arms with RGX-104 as monotherapy and in combination with nivolumab, ipilimumab, or docetaxel. Various markers including intratumoral ApoE and its receptor LRP1 in biopsy specimens, gene expression of LXR-targets in whole blood, serum markers including cytokines and lipids, as well as immune cell types such as MDSC, CD8 T-cells, and neutrophils in peripheral blood from patients were monitored at several time points. PK metrics were tracked to assess dose response relationships. Clinical outcomes such as objective response, time to disease progression, and duration on therapy were used for exploratory correlative analyses. A generally dose dependent increase in steady state exposure to RGX-104 was observed among all cohorts; the lowest efficacious exposure among patients with partial response was ~14,000 ng*h/mL. Treatment with RGX-104 at doses ranging from 120 mg BID to 240 mg BID induced expression of LXR targets, ApoE [2.7X (p=0.008) to 7.1X (p=0.007)] and ABCA1 [ 6.3X (p=1.20E-03) to 7X (p=8.1E-04] over baseline in a generally dose-dependent manner as assessed in whole blood. Similarly, MDSC depletion, ranging from 70%-90% relative to baseline, was observed in patients treated with RGX-104 along with concomitant CD8 T-cell activation; similar effects were noted in patients in combination cohorts. A model to explore dose dependency of change in immune cell types suggested that baseline levels of MDSC were most predictive of the magnitude of MDSC reduction after treatment, and that favorable clinical outcomes correlate with the extent of MDSC reduction and T cell activation. Low baseline levels of tumoral ApoE were associated with greater clinical benefit, with almost all patients with stable disease or partial response exhibiting ApoE tumor positive score of ≤20%; these patients also exhibited low/negative PD-L1 (<1%) staining, revealing a target specific tumor biomarker and PD-L1 subset that could support prospective patient selection. These and additional markers will be tracked in expansion cohorts of RGX-104 in combination with pembrolizumab and carboplatin/pemetrexed for 1st line treatment of patients with metastatic non-small cell lung cancer (PD-L1 <1%) and in combination with docetaxel for 2nd line treatment of patients with small cell lung cancer.

Citation Format: Monica Mita, Alan Mita, Erika Hamilton, Gerald S. Falchook, Michael Postow, Bartosz Chmielowski, Russell J. Schilder, James Strauss, Emerson Lim, Shubham Pant, Angela Jain, Oliver Rixe, Rebecca Redman, Kevin B. Kim, Tomislav Dragovich, R. Donald Harvey, Igor Puzanov, Nimisha Schneider, Renee Deehan, Tobi Guennel, Joe Lin, Sohail Tavazoie, Roger Waltzman, Eric Rowinsky, Michael Szarek, Subhasree Sridhar, Robert Busby, Narayan Lebaka, Celia Andreu, Isabel Kurth, David Darst, Masoud Tavazoie, Syed Raza, Robert Wasserman, Foster C. Gonsalves. Correlative analysis of pharmacokinetics and pharmacodynamics of RGX-104, a first-in-class Liver-X-Receptor (LXR) agonist, and clinical outcomes in patients with advanced solid tumors [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 LB-133.

Abstract CT146: RGX-104, a first-in-class immunotherapy targeting the liver-X receptor (LXR): Initial results from the phase 1b RGX-104 plus docetaxel combination dose escalation cohorts

Background: RGX-104 is a small-molecule LXR agonist that modulates innate immunity via transcriptional activation of the ApoE gene. Binding of ApoE to its receptor LRP8 robustly inhibits angiogenesis and depletes myeloid derived suppressor cells (MDSC), thereby activating cytotoxic T-lymphocytes. MDSCs are associated with resistance to both checkpoint inhibitors (CPI) and chemotherapy, providing a rationale for combination therapy with RGX-104. We previously reported results of the RGX-104 monotherapy dose escalation for which 26 patients with refractory solid tumors were treated in 5 dose cohorts. On-target AEs included hyperlipidemia and neutropenia. Flow-cytometry demonstrated MDSC depletion with associated T cell activation, which correlated with clinical benefit. A 40% disease control rate (DCR; SD+PR) was observed with a confirmed partial response (PR) by irRC (>79% reduction in index lesions) in a patient with platinum-refractory small cell lung cancer (SCLC). Methods: Here, we present the safety, biomarker and efficacy results of the docetaxel combination arm of the RGX-104 trial. Cohort 1- RGX-104 80 mg BID, and docetaxel at 35 mg/m2 days 1, 8, and 15 of a 28-day cycle; Cohort 2- RGX-104 80 mg BID, 5 days-on/2 days-off (5/2), and docetaxel at 28 mg/m2 on above schedule. Cohort 3- RGX-104 100 mg BID (5/2), and docetaxel as per cohort 2. Results: As of February 7, 2020, 11 patients with refractory solid tumors have been treated in 3 dose escalation cohorts with RGX-104 plus docetaxel. AEs were consistent with the individual toxicity profiles of docetaxel and RGX-104, with neutropenia being the most common AE and dose-limiting in cohort 1. The 5/2 dosing regimen in cohorts 2 and 3 resulted in significantly fewer episodes of neutropenia and no DLTs, while maintaining pharmacodynamic effects including >50% sustained MDSC depletion. A 66% DCR was observed in 9 evaluable patients including 2 patients in cohort 2 with PRs, a CPI-refractory SCCHN patient and a CPI-refractory melanoma patient, who remains on treatment at 36 weeks. A patient with melanoma in Cohort 3 had an initial assessment of SD and continues on study at 14 weeks. Clinical responses were associated with increases in T cell activation markers exceeding that generally observed with RGX-104 alone (up to a 5-fold increase in total CD8 T cells, a 7-fold increase in LAG-3+ CD8 T cells, and a 75-fold induction of serum IFNγ). Conclusion: The safety profile and marked pharmacodynamic and clinical activity of the RGX-104/docetaxel combination in CPI-refractory patients supports further development of this regimen. Consequently, the RGX-104/docetaxel regimen will be evaluated in a Phase 1b/2 expansion cohort in patients with relapsed/refractory ES-SCLC/high grade-neuroendocrine tumors.

Citation Format: Emerson Lim, Erika P. Hamilton, Rebecca Redman, Michael A. Postow, Russell J. Schilder, Monica M. Mita, Alain C. Mita, Bartosz Chmielowski, James Strauss, Angela Jain, Shubham Pant, Olivier Rixe, Tomislav Dragovich, R. Donald Harvey, Igor Puzanov, Kevin B. Kim, Eric K. Rowinsky, Michael Szarek, Foster Gonsalves, Isabel Kurth, Celia Andreu, Robert W. Busby, David Darst, Masoud Tavazoie, Syed Raza, Narayan Lebaka16, Robert Wasserman, Gerald Falchook. RGX-104, a first-in-class immunotherapy targeting the liver-X receptor (LXR): Initial results from the phase 1b RGX-104 plus docetaxel combination dose escalation cohorts [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 CT146.

Patient Experiences with Avelumab in Treatment-Naïve Metastatic Merkel Cell Carcinoma: Longitudinal Qualitative Interview Findings from JAVELIN Merkel 200, a Registrational Clinical Trial

BACKGROUND AND OBJECTIVE

Avelumab is approved for the treatment of metastatic Merkel cell carcinoma, a rare aggressive skin cancer with a poor prognosis. The aim of this qualitative study embedded in a clinical trial was to explore patient experiences while receiving avelumab.

METHODS

All treatment-naïve patients with metastatic Merkel cell carcinoma entering part B of the phase II, open-label, international, JAVELIN Merkel 200 trial (NCT02155647) were invited to participate in optional semi-structured phone interviews before avelumab administration (baseline) and at weeks 13 and 25. Interviews were conducted by trained professionals, audio-recorded, transcribed and analysed. Key concepts identified at baseline were assessed during follow-up interviews.

RESULTS

Twenty-nine patients completed the baseline interview; 19 had at least one follow-up interview. Baseline interviews described the patients' challenging journeys before being correctly diagnosed with Merkel cell carcinoma, the negative psychological burden of living with a symptomless disease and the hope for avelumab to be a successful therapy. During the trial, most patients reported an increased or continued sense of hope and willingness to fight metastatic Merkel cell carcinoma. Patients who self-reported disease improvement (n = 12) also reported stability or improvement in physical well-being and ability to do daily activities, having more energy, worrying less and being optimistic. Six patients who reported their condition as stable (n = 4) or worsened (n = 3) reported a worsening of physical well-being. Nine patients reported fatigue/tiredness on the day of and after receiving avelumab. Baseline and longitudinal experiences were similar across countries.

CONCLUSIONS

This study suggests that patients experience perceptible benefits in physical and psychological well-being following treatment success with first-line avelumab in metastatic Merkel cell carcinoma.

Low Rates of Chemotherapy Use for Primary, High-Grade Soft Tissue Sarcoma: A National Cancer Database Analysis

BACKGROUND

There is conflicting evidence regarding the role of chemotherapy for high-grade soft tissue sarcoma (STS) in adults. We sought to characterize patterns of chemotherapy use, including multiagent and neoadjuvant chemotherapy, in the United States.

PATIENTS AND METHODS

Using the National Cancer Database, we identified 19,969 adult patients who underwent surgical resection for primary high-grade STS from 2004 to 2016. Using logistic regression, we examined factors associated with overall, multiagent, and neoadjuvant chemotherapy use.

RESULTS

Chemotherapy was administered to 22% (n=4,377) of the study population. Among patients treated using chemotherapy, 85% received multiagent treatment and 47% received neoadjuvant treatment. On multivariate analysis, factors associated with chemotherapy use included tumor size, depth, histology, and primary site; receipt of radiation treatment; younger age; higher patient income; and academic treatment facility. Factors associated with multiagent chemotherapy use included tumor histology, tumor primary site, and younger age. Factors associated with neoadjuvant chemotherapy use included tumor size, depth, margin status, and primary site; receipt of radiation treatment; higher patient income; academic treatment facility type; and distance to treatment facility. Treatment at a high-volume facility was the only factor associated with overall, multiagent, and neoadjuvant chemotherapy use. No significant temporal trend was seen in overall, multiagent, or neoadjuvant chemotherapy use.

CONCLUSIONS

Overall chemotherapy use was low (22%). The variability in chemotherapy use was driven by clinical, patient, demographic, and facility factors. Among patients treated with chemotherapy, the use of multiagent chemotherapy was high (85%), and nearly half received neoadjuvant therapy. There was a discrepancy in the use of chemotherapy-including neoadjuvant and multiagent chemotherapy-between high- and low-volume treatment centers.

A phase I, first-in-human, open-label, dose-escalation study of MGD013, a bispecific DART molecule binding PD-1 and LAG-3, in patients with unresectable or metastatic neoplasms

3004

Background: MGD013 is an investigational, first-in-class, Fc-bearing bispecific tetravalent DART molecule designed to bind PD-1 and LAG-3 and sustain/restore the function of exhausted T cells. MGD013 demonstrates ligand blocking properties consistent with anti-PD-1 and anti-LAG-3 benchmark molecules, and improves T cell responses beyond that observed with benchmark or component antibodies alone or in combination. Methods: This study characterizes the safety, tolerability, dose-limiting toxicities, maximum tolerated dose (MTD), PK/PD, and antitumor activity of MGD013 in patients (pts) with advanced solid and hematologic malignancies. Sequential single-pt cohorts were treated with escalating flat doses of MGD013 (1-1200 mg IV every 2 weeks), followed by a 3+3 design. Tumor-specific expansion cohorts are being treated at the recommended Phase 2 dose of 600 mg. Results: At data-cutoff, 50 pts (46% checkpoint-experienced) were treated in Dose Escalation, and 157 pts (32% checkpoint-experienced) in Cohort Expansion. No MTD was defined. Treatment-related adverse events (TRAEs) occurred in 146/207 (70.5%) pts, most commonly fatigue (19%) and nausea (11%). The rate of Grade ≥ 3 TRAEs was 23.2%. Immune-related AEs were consistent with events observed with anti-PD-1 antibodies. Mean half-life was 11 days; peripheral blood flow cytometry analyses confirmed full and sustained on-target binding during treatment at doses ≥ 120 mg. Among 41 response-evaluable [RE] dose escalation pts, 3 confirmed partial responses [cPRs] (triple negative breast cancer [TNBC], mesothelioma, gastric cancer) per RECIST 1.1 were observed, while 21 pts had stable disease [SD]. Among select expansion cohorts, PRs have been observed in epithelial ovarian cancer (n=2; both cPRs, and 7 with SD among 15 RE pts) and TNBC (n=2; 1 cPR, 1 unconfirmed PR [uPR], and 5 with SD among 14 RE pts). In a cohort of pts with HER2+ tumors treated with MGD013 in combination with margetuximab (investigational anti-HER-2 antibody), 3 PRs have been observed (breast [n=2], colorectal [n=1]; 1 cPR, 2 uPRs) and 2 pts with SD among 6 RE pts. Objective responses have been observed in several pts after prior anti-PD-1 therapy. Investigations into potential correlative biomarkers including LAG-3 and PD-1 are ongoing. Conclusions: MGD013, a novel molecule designed to coordinately block PD-1 and LAG-3, has demonstrated an acceptable safety profile and encouraging early evidence of anti-tumor activity. Clinical trial information: NCT03219268 .

A phase II, multicenter study of encorafenib/binimetinib followed by a rational triple-combination after progression in patients with advanced BRAF V600-mutated melanoma (LOGIC2)

10022

Background: LOGIC2 evaluates the benefit of a 3rd agent added to encorafenib (enco)/binimetinib (bini), selected at progression based on the genetic tumor evolution. Methods: In part I/run-In, pts were treated with enco/bini until disease progression (as defined per RECIST v1.1). Foundation One NGS was applied on a baseline sample and on a PD sample. Based on the genetic evolution between the biopsy at inclusion (bxI) and at progression (bxPD) and clinical considerations, pts entered part II and received one of four 3rd agent additions to enco/bini combinations: A. LEE011 (CDK4/6 inhibitor), B. BKM120 (PI3K inhibitor), C. INC280 (c-Met inhibitor), or D. BGJ398 (FGFR inhibitor). An adaptive Bayesian logistic regression model (BLRM) guided by the escalation with overdose control (EWOC) principle was used to make dose escalation decisions. Assessments include objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), and safety. Data cutoff for this analysis was May 12, 2019. Data is as is. Part 1 of study is ongoing. Part 2 of study is closed to enrollment. Results: 58 pts enrolled into part II (group A=38; B=6; C=13; D=1). 29 pts were assigned to treatment based on bxPD results (Table). In groups A, B, and C, the confirmed ORR was 5.3%, 0%, and 0%, and the DCR was 26.3%, 16.7%, and 15.4%, with median PFS of 2.1, 1.6, and 2.2 months, respectively. Safety was consistent with known profiles of the individual agents. Conclusions: Triple therapy is feasible when a 3rd agent is added to enco/bini at progression based on genetic alterations, although activity observed was low. Further exploration to identify patterns of resistance susceptible to the addition of a 3rd agent is needed. Gene alterations for enrollment into part 2. Clinical trial information: NCT02159066. [Table: see text]

A phase Ia/Ib, open-label first-in-human study of the safety, tolerability, and feasibility of gene-edited autologous NeoTCR-T cells (NeoTCR-P1) administered to patients with locally advanced or metastatic solid tumors

TPS3151

Background: Neoepitopes (neoE) derived from private tumor-exclusive mutations represent compelling targets for personalized TCR-T cell therapy. An ultra-sensitive and high-throughput process was developed to capture tumor mutation-targeted CD8 T cells from patient blood. NeoTCRs cloned from the captured CD8 T cells, when engineered into fresh CD8 and CD4 T cells, effected killing of patients’ autologous tumor cells in vitro. These observations have been leveraged for the development of a fully personalized adoptive T cell therapy (NeoTCR-P1). A Phase 1 clinical trial testing NeoTCR-P1 in subjects with solid tumors is ongoing (NCT03970382). Methods: During the initial trial phase, escalating doses of NeoTCR-P1 T cells administered without and with IL-2 in the regimen, and following conditioning chemotherapy, will be evaluated in subjects with advanced or metastatic solid tumors (melanoma, urothelial cancer, colorectal cancer, ovarian cancer, HR+ breast cancer, and prostate cancer). The objective of the Phase 1a study is to establish a recommended Phase 2 dose. Primary endpoints include the incidence and nature of DLTs and overall process feasibility. The proliferation, persistence, and trafficking of NeoTCR-T cells will be characterized. In the expansion trial phase, preliminary anti-tumor activity of NeoTCR-P1 will be assessed in selected tumors. The combination of NeoTCR-P1 dosing plus nivolumab will be tested in a Phase 1b study. Conclusion: This is the first clinical study of an autologous, fully personalized adoptive T cell therapy directed against private tumor-exclusive mutations, generated without using recombinant viral vectors. Clinical trial information: NCT03970382 .

Clinical outcomes in patients with BRAFV600 mutant melanoma and undetectable circulating tumor DNA treated with dabrafenib and trametinib

10059

Background: Circulating tumor DNA (ctDNA) analysis has been promoted as a less-invasive surrogate assay for tumor-tissue based tumor oncogene analysis. Here, we associate detection of BRAF mutant ctDNA with PFS and OS in patients with tissue-confirmed BRAFV600 mutant melanoma enrolled in S1320, a randomized phase 2 clinical trial of continuous versus intermittent dosing of dabrafenib and trametinib. Methods: Patients with BRAFV600 melanoma received continuous therapy with dabrafenib and trametinib for 8 weeks after which patients were randomized 1:1 to proceed with intermittent treatment on a 3-week-off, 5-week-on schedule or to continue with continuous therapy. Pre-treatment blood samples were interrogated using the Guardant 360 ctDNA assay for all exons of 30 known oncogenes including BRAF and for all exons with known oncogenic mutations in the COSMIC database in 40 additional oncogenes. Clinical responses were assessed at 8-week intervals by RECIST v1.1 and PFS and OS estimates were compared using log-rank test in patients with detectable versus undetectable BRAFV600 mutant ctDNA,. Results: Somatic BRAFV600E or BRAFV600K ctDNA was detected in 34 of 50 patients with baseline (before lead-in cycle 1) blood samples available for analysis including 16 of 23 (70%) patients randomized to continuous dosing, 15 of 21 (71%) randomized to intermittent dosing, and 3 of 6 (50%) who were not randomized due to disease progression at 8 weeks or other factors. Four additional patients had other detectable somatic mutations but no detectable BRAFV600 ctDNA at baseline, and 12 patients had no detectable somatic ctDNA mutations at baseline. Detection of BRAFV600 ctDNA was associated with baseline disease stage (p = 0.008). There was no difference in the overall response rate based on baseline ctDNA detection. Detection of ctDNA at baseline was associated with worse PFS (median BRAFV600 ctDNA positive = 5.8; 95% CI: 4.2-9.6 months, BRAFV600 ctDNA negative = 21.4 mos; 95% CI 10.4-NA; measured from registration to lead-in cycle 1, p = 0.001) and OS (BRAFV600 ctDNA positive = 17.8 mos; 95% CI 9.76-NA, BRAFV600 ctDNA negative = not reached; 95% CI NA-NA, p = 0.0021). Conclusions: The absence of detectable BRAFV600 ctDNA at baseline is associated with improved PFS and OS in patients receiving treatment with dabrafenib and trametinib. Clinical trial information: NCT02196181.

Molecular profiling and clinical characteristic of malignant melanoma in younger patients

e22087

Background: Combination of clinical and molecular data has not yet been well established in adolescent and younger adult patients with melanoma Methods: We performed a retrospective analysis of the molecular profiles and clinical outcome of patients diagnosed at the age younger than 40 treated at UCLA during 2010 to 2019. Patient’s molecular profile, characteristics, and treatment outcome were described using descriptive statistic. Kaplan-Meier curve was used for disease-free survival (DFS) and overall survival (OS). Results: 150 patients with a median age of 29 year (12-39) were analyzed. 101 (67.3%) patients had cutaneous melanoma, 49 (32.7%) had localized uveal melanoma. Of those 101, 23.8% had pre-existing benign or congenital nevus. 70/101 (69.3%) was stage I-II, 26/101 (25.7%) stage III and 5/101 (4.9%) stage IV. Of those 37 patients with molecularly characterized tissue, 23 (62%) had BRAF mutation including 17 V600E, 4 V600 unknown codon, 2 G469A, 2 NRAS and 1 NF-1 mutation. 11/37 were BRAF negative. 79.6% of patients who were not tested were stage I. For patients with stage III, 16/26 (61%) received adjuvant immunotherapy, none of adjuvant targeted therapy. At 35.1 months follow-up time, 27/96 (28%) localized cutaneous melanoma experienced relapse. 1-year DFS was 73% in adjuvant vs. 90% in no adjuvant immunotherapy group. Among 49 uveal melanoma patients, the median age was 27 years old. 23/49 (49%) had a T1 tumor, 18/49 (36.7%) T2, 6/49(12.2%) T3, 1/49(2%) T4. At 45 months follow-up time, three (6.1%) patients developed metastasis. 5-year DFS and OS was 90% and 100%, respectively. 45 patients had tissue for gene expression profiling and/or FISH testing. 15/45 (33%) had class IA, 13/45 (28%) had class IB, and 8/45 (17.7%) had class 2. 24 samples were analyzed by FISH: 14 with disomy 3, 5 with complex disomy 3 with gain of chromosome 6 or 8, and 5 with monosomy 3. Conclusions: Similarly to general population, most of younger patients with melanoma are diagnosed with stage I disease. Among patients with stage III melanoma treated with adjuvant immunotherapy 1-year DFS was comparable to the general population. Patients with stage III who did not receive adjuvant therapy had an excellent DFS which confirms that the decision on selecting patients for treatment was appropriate. The prognosis of younger patients with uveal melanoma was much better than predicted by molecular testing, and much better than expected regardless of gene expression profile or cytogenetic testing.

Phase I/II dose-escalation and expansion study of FLX475 alone and in combination with pembrolizumab in advanced cancer

TPS3163

Background: Regulatory T cells (Treg) can dampen anti-tumor immune responses in the tumor microenvironment (TME). The predominant chemokine receptor on human Treg is CCR4, the receptor for the chemokines CCL17 and CCL22, which are produced by tumor cells, tumor-associated macrophages and dendritic cells, as well as by effector T cells (Teff) in the setting of an inflammatory anti-tumor response. Preclinical studies with orally-available CCR4 antagonists have demonstrated potent inhibition of Treg migration into tumors, an increase in the intratumoral Teff/Treg ratio, and anti-tumor efficacy as a single agent and in combination with checkpoint inhibitors. In a first-in-human trial conducted in healthy volunteers, the oral CCR4 antagonist FLX475 was demonstrated to be well tolerated with outstanding PK properties. A robust PD assay measuring receptor occupancy on circulating Treg demonstrated the ability to safely achieve exposure levels predicted to maximally inhibit Treg recruitment into tumors via CCR4 signaling. These human PK, PD, and safety data have enabled a streamlined design of a Phase 1/2 study of FLX475 in cancer patients both as monotherapy and in combination with checkpoint inhibitor. Methods: This clinical trial is a Phase 1/2, open-label, dose-escalation and cohort expansion study to determine the safety and preliminary anti-tumor activity of FLX475 as monotherapy and in combination with pembrolizumab. The study is being conducted in 2 parts, a dose-escalation phase (Part 1) and a cohort expansion phase (Part 2). In Part 1 (Phase 1) of the study, at least 3 to 6 eligible subjects are being enrolled in sequential cohorts treated with successively higher doses of FLX475 as monotherapy (Part 1a) or in combination with pembrolizumab (Part 1b). In Part 2 (Phase 2) of the study, expansion cohorts of both checkpoint-naïve and checkpoint-experienced patients with tumor types predicted to be enriched for Treg and/or CCR4 ligand expression (i.e. “charged tumors”) -- including both EBV+ and HPV+ tumors and NSCLC, HNSCC, and TNBC -- will be enrolled using a Simon 2-stage design. As of February 4, 2020, Phase 1 dose escalation has been completed and a recommended Phase 2 dose chosen for both FLX475 monotherapy and combination therapy with pembrolizumab. Enrollment into Phase 2 expansion cohorts has been initiated. Clinical trial information: NCT03674567 .

A Phase II Trial of 5-Day Neoadjuvant Radiotherapy for Patients with High-Risk Primary Soft Tissue Sarcoma

PURPOSE

In a single-institution phase II study, we evaluated the safety of a 5-day dose-equivalent neoadjuvant radiotherapy (RT) regimen for high-risk primary soft tissue sarcoma.

PATIENTS AND METHODS

Patients received neoadjuvant RT alone (30 Gy in five fractions) to the primary tumor with standard margins. The primary endpoint was grade ≥2 late-radiation toxicity. Major wound complications, local recurrences, and distant metastases were also examined. In exploratory analysis, we evaluated germline biomarkers for wound toxicity and the effects of the study on treatment utilization.

RESULTS

Over 2 years, 52 patients were enrolled with median follow-up of 29 months. Seven of 44 evaluable patients (16%) developed grade ≥2 late toxicity. Major wound complications occurred in 16 of 50 patients (32%); a signature defined by 19 germline SNPs in miRNA-binding sites of immune and DNA damage response genes, in addition to lower extremity tumor location, demonstrated strong predictive performance for major wound complications. Compared with the preceding 2-year period, the number of patients treated with neoadjuvant RT alone at our institution increased 3-fold, with a concomitant increase in the catchment area.

CONCLUSIONS

A shorter 5-day neoadjuvant RT regimen results in favorable rates of wound complications and grade ≥2 toxicity after 2-year follow-up. Five-day RT significantly increased utilization of neoadjuvant RT at our high-volume sarcoma center. With further validation, a putative germline biomarker for wound complications may guide safer RT utilization.

A phase I study evaluating COM701 monotherapy and in combination with nivolumab in patients with advanced solid malignancies

TPS23

Background: COM701 is a novel 1st-in-class monoclonal antibody that binds with high affinity to poliovirus receptor related immunoglobulin domain containing (PVRIG) blocking its interaction with its ligand, PVRL2. In preclinical experiments inhibition of PVRIG alone and in combination with a PD-1 inhibitor leads to activation of T cells in the tumor microenvironment generating an anti-tumor immune response leading to tumor growth inhibition. Novel checkpoint therapies are needed for the treatment of patients with advanced malignancies. We hypothesized that COM701 monotherapy and in combination with nivolumab will be safe and tolerable and demonstrate preliminary antitumor activity in pts with advanced solid malignancies. Methods: This ongoing phase 1 study (NCT03667716) is evaluating the safety and tolerability of escalating doses of COM701 monotherapy IV Q3 or Q4 weekly and in combination with nivolumab 360 mg IV Q3 weekly or 480 mg IV Q4 weekly. Key Inclusion Criteria: Age ≥18 yrs, histologically or cytologically confirmed advanced solid malignancy and has exhausted all available standard therapy, ECOG performance status 0-1, prior ICI permissible. Key Exclusion Criteria: Symptomatic interstitial lung disease or inflammatory pneumonitis, untreated or symptomatic central nervous system metastases. Primary outcome measures are the incidence of adverse events and dose-limiting toxicities (21-day or 28-day DLT window), pharmacokinetics of COM701 and to identify the maximum tolerated dose and/or the recommended dose for expansion. Key secondary outcome measures are to characterize the immunogenicity and preliminary antitumor activity of COM701 as monotherapy and in combination with nivolumab. Study Design: Hybrid accelerated titration and 3+3 study design. Statistical Considerations: Adverse events graded as per CTCAE v4.03, responses as per RECIST v1.1. Analyses of all study objectives are descriptive and hypothesis generating. As of the date of this submission dose level 8 of COM701 monotherapy and dose level 3 of the combination arm are open to enrollment. Updated data will be presented at the conference. Clinical trial information: NCT03667716.

Health Care Resource Utilization and Costs in First-Line Treatments for Patients with Metastatic Melanoma in the United States

BACKGROUND

The treatment landscape for patients with metastatic melanoma has changed dramatically with the introduction of novel therapies, such as targeted therapies and immunotherapies, in recent years. Health care resource utilization (HCRU) and cost data are needed to further evaluate these treatments in a value-based health care system.

OBJECTIVE

To examine HCRU and total cost of care among U.S. metastatic melanoma patients treated with first-line systemic therapies, including immunotherapies, targeted therapies, and chemotherapy.

METHODS

A retrospective observational study was conducted using a U.S. claims database. Adults with ≥ 2 claims for melanoma and ≥ 1 claim for metastasis between January 1, 2012, and June 30, 2017, were identified. Patients had pharmacy and medical enrollment ≥ 6 months before and ≥ 3 months following first-line treatment start. Per patient per month (PPPM) HCRU and costs were calculated by first-line treatment drug class: PD-1 inhibitors, CTLA-4 inhibitors, CTLA-4 + PD-1 combination, BRAF monotherapy, BRAF + MEK combination, and chemotherapy. Adjusted odds ratios (ORs) for HCRU were estimated by logistic regressions and adjusted costs were estimated by generalized linear models using log-link with gamma distribution to control for differences in patient characteristics across groups.

RESULTS

Among 1,599 metastatic melanoma patients (PD-1, n = 255; CTLA-4, n = 555; CTLA-4 + PD-1, n = 88; BRAF, n = 210; BRAF + MEK, n=102; chemotherapy=389), mean age ranged from 59-68 years, and the majority were male (62%). Any hospitalization during first-line treatment was less frequent among PD-1-treated patients (25.9%) compared with 34.7%-45.5% of all other groups (all P < 0.05). PPPM hospitalizations were lowest in PD-1 (0.06) compared with 0.09-0.16 across all other groups (all P < 0.05), and PPPM emergency department (ED) visits were lowest in PD-1 (0.09) compared with 0.13-0.18 across all other groups (all P < 0.05), except for BRAF + MEK (0.14, P = 0.08). CTLA-4, CTLA-4 + PD-1, and BRAF + MEK had increased odds of hospitalization compared to PD-1 (adjusted ORs = 2.10, 2.35, 2.15, respectively; all P < 0.05). Total adjusted PPPM costs were significantly lower for PD-1 ($13,059) compared with CTLA-4 ($25,583), CTLA-4 + PD-1 ($31,310), and BRAF + MEK ($21,517) and higher compared to BRAF ($8,158) and chemotherapy ($6,361).

CONCLUSIONS

Hospitalizations and ED visits represent important HCRU for metastatic melanoma patients and were lowest among PD-1-treated patients compared with any other systemic therapies (except for ED visits when compared with BRAF + MEK). Total monthly costs varied substantially across first-line regimens and were significantly lower in PD-1-treated patients compared with patients treated with CTLA-4, CTLA-4 + PD-1, and BRAF + MEK.

DISCLOSURES

This study was funded by Merck Sharp & Dohme, a subsidiary of Merck & Co. Klink, Feinberg, and Nero are employees of Cardinal Health Specialty Solutions, which received funding from Merck to conduct this study. Chmielsowki is a consultant to Merck but received no funding for the development of this manuscript. Ahsan and Liu are employees of Merck. Chmielowski reports advisory board/speaker fees from Bristol-Myers Squibb, Merck, Genentech/Roche, Iovance Biotherapeutics, HUYA Bioscience International, Compugen, Array BioPharma, Regeneron, Biothera, Janssen, and Novartis. Ahsan has a patent (US20160008380A1) pending.

An open label, multicenter phase II study combining imprime PGG (PGG) with pembrolizumab (P) in previously treated metastatic triple-negative breast cancer (mTNBC)

2550

Background: Checkpoint inhibitor (CPI) monotherapy shows limited clinical response in previously treated mTNBC patients (pts) (Table). Agents are needed that extend this benefit to more mTNBC pts. PGG is a novel, IV administered PAMP that, in pts with 20ug/ml anti-beta glucan antibody (ABA+), activates innate immune cells. Preclinically, PGG reprograms myeloid cells to repolarize the immunosuppressive tumor microenvironment & enhance antigen presentation, driving T cell activation- the mechanistic basis to explore PGG + P in mTNBC patients. Methods: 44 mTNBC pts ( 1 line of chemotherapy [Tx] for metastatic disease, ABA) received PGG (4 mpk IV weekly) + P (200 mg IV q3w) until PD or intolerable toxicity. 1° endpoints were ORR by RECIST v1.1 & safety. 2° endpoints included OS & DCR. CT scans (q6 wks) were reviewed locally. Tumor biopsies (pre & 6 wks on Tx) & blood samples were assessed for PGG-mediated immune activation. Results: Table shows IMPRIME 1 clinical response data (Keynote086, PCD4989g shown for context). Confirmed response was also evident in pts with liver or visceral metastases, high LDH. 10 IMPRIME 1 pts were originally ER/PR+, received hormonal Tx and progressed to TNBC. Of these, 5 are confirmed PR, 4 SD (3 still on Tx), 1 PD. No unexpected safety signals were observed. Conclusions: These are the first clinical data to suggest that PGG provides added clinical benefit for pts with previously treated mTNBC and support further development of PGG + P for mTNBC. Clinical trial information: NCT02981303. [Table: see text]

Pathologic discordance in sarcomas: Prospective comparison of external and sarcoma center pathologic diagnosis

11020

Background: With more than 80 different histologic subtypes, sarcomas are a unique pathologic challenge. As therapeutic decisions have become histology-specific, obtaining an accurate pathologic diagnosis is critical in guiding treatment decisions. The aim of this study is to determine the discordance between the diagnosis rendered by an external non-specialized pathologist and pathologic re-review by a specialized sarcoma pathologist at a high-volume sarcoma center. Methods: Patients who presented at the UCLA Multidisciplinary Sarcoma Conference (MSC) in 2017 that had a pathologic diagnosis from an outside facility were included in this study. All specimens underwent pathologic re-review at UCLA by an experienced sarcoma pathologist. The pathology was classified as concordant (identical diagnoses), minor discordance (difference with minor impact on prognosis/therapy) and major discordance (difference with significant impact on prognosis/therapy). Results: 1350 patients were presented at the UCLA MSC in 2017. Of the 635 new patients, 196 presented with an outside pathologic diagnosis and underwent pathologic re-review at UCLA. 44% (n = 87) were concordant, 22% (n = 43) had minor discordance, and 34% (n = 66) had major discordance. Major discordance included substantial discrepancies in histologic subtype (n = 24, 36%), benign/malignant mismatch (n = 23, 35%), diagnostic from non-diagnostic (n = 12, 18%) and major grading discrepancy (n = 7, 11%). Major discordance was most often seen in biopsies [needle (n = 27, 32%), incisional (n = 30, 44%)] as compared to resection (n = 9, 21%). Conclusions: 56% of external non-specialized sarcoma pathologic diagnoses were discordant from specialized sarcoma pathologist review, 34% of which were major discordances. Pathologic re-review of a presumed sarcoma by a specialized sarcoma pathologist is critical for both patient care and investigational studies. [Table: see text]

A randomized phase II study of nivolumab monotherapy versus nivolumab combined with ipilimumab in advanced gastrointestinal stromal tumor (GIST)

11017

Background: Most GISTs are driven by mutations in KIT and PDGFRa and secondary mutations are felt to confer resistance to TKIs. In advanced/metastatic GIST, the benefit of second line TKIs and beyond is progressively less after imatinib failure. As such, novel non-TKI approaches are important to explore. Here we report interim analyses of safety and efficacy in advanced GIST patients treated with immunotherapy. Methods: Patients with advanced/metastatic GIST refractory to at least imatinib were enrolled on a randomized, parallel group, unblinded Phase 2 trial of either nivo (240 mg Q2wks) or nivo (240 mg Q2wks) with ipi (1mg/kg Q6wks) for up to 2 years. The primary endpoint was the objective response rate(ORR) of nivo alone or nivo + ipi by RECIST 1.1 criteria. Imaging was assessed by investigator and 3 independent radiologists. Patients were randomized 1:1 and were restaged every 8 weeks. With a sample size of 20 per group, an exact binomial test with a nominal 0.050 one-sided significance level will have 82% power to detect the difference between the null hypothesis response rate 1.5% and the alternative response rate of 15%. Secondary objectives are to ascertain the PFS, CBR, RR by Choi criteria and safety. Blood and biopsies are also being collected. Results: At cutoff, 29 patients (27 evaluable) with a median of 3 (1-7) lines of prior therapies have started on trial. In the nivo only arm, 7/15 pts had a best response of SD for a CBR of 46.7% with the median PFS being 8.57 wks. In the nivo + ipi arm, 1/12 patients had a PR and 2/12 have SD for a CBR of 25.0% (95% exact C.I. 5.5%-57.2%) with a median PFS of 9.1 wks. 8 patients have been on therapy for more than 6 months and two patients with a KIT Exon 17 mutation had radiographic disease shrinkage. Most AEs were grades 1-2 with fatigue (37%) being the most common. 4 Grade 3/4 AEs occurred in the nivo and ipi arm (hyperglycemia, weakness, diarrhea x 2) and 4 grade 3/4AEs occurred in the nivo arm (DKA, hyperglycemia, rash, fatigue). Pretreatment biopsies have been obtained in all patients and blood has been collected on all patients for correlative analysis. Conclusions: In a heavily pretreated GIST population, responses and disease control with both nivo and nivo + ipi were observed. To date, the drugs have been well tolerated and no new safety signals have been observed in this disease state. Clinical trial information: NCT02880020.

Retrospective analysis of adjuvant treatment for localized, operable uterine leiomyosarcoma

11072

Background: Surgery is the standard of care for uterine leiomyosarcoma, but recurrence rates are high and outcomes are poor. Standard adjuvant treatment of localized uterine leiomyosarcoma(uLMS) has not yet been established as clinical trials to address this question have been small or hindered by slow accrual. Methods: We reviewed the medical records of patients with uLMS who underwent upfront surgery between 2000-2018. We evaluated the clinical characteristics and adjuvant therapy on outcomes. Patient characteristics and treatment outcomes were described using descriptive statistics. Kaplan-Meier survival analysis was used for DFS. Cox proportional hazard regression was used to compare difference between groups. Results: 59 patients with a median age of 52 years were analyzed and the median time from surgery to adjuvant treatment was 47 days. 48/59 (81.4%) underwent TAH-BSO. 64.4% were FIGO stage I, 16.9% were stage II and 6.7% were stage III. The median tumor size was 11 cm (range: 3-21cm) and the median mitotic rate was 13 mitoses/ 10 high-power fields (HPF), (range: 1-63). 34/59 (57.6%) of patients received adjuvant chemotherapy +/- radiation therapy and 25 patients (42.3%) did not receive adjuvant treatment. With a median follow-up time of 42.8 months, 42 patients (71.2%) had disease relapse and 15 (35.7%) had pulmonary metastases. The median disease-free survival (mDFS) for all patients was 23.1 months. Any adjuvant treatment (chemotherapy or radiation) had a trend toward longer mDFS than no adjuvant treatment (36.6 vs 13.6 months, p = 0.14). Patients who had adjuvant chemotherapy had a non-significant longer mDFS compared to who did not receive any adjuvant treatment (33.8 vs 13.6 months, p = 0.18). Patients with stage I disease had trend towards higher mDFS in the chemotherapy group, it was not statistically significant (29.7 vs 16.6 months, p = 0.59). Multivariate analysis found that the independent prognostic factors for worse DFS included tumor size larger than 10 cm, and mitotic rate over 10/ 10HPF. More morcellated specimens were found in non-adjuvant treatment arm (36%) compare to 8% in adjuvant arm. In the non-treatment arm, 14 patients had recurrences within 6 months. Conclusions: In a retrospective uLMS population, the mDFS was 23.1 months. Tumor size > 10cm and mitotic rate > 10/10 HPF were independent prognostic factors for lower DFS. The non-treatment group had a significantly higher number of patient with morcellization and relapsed within 6 months, confounding analyses of the impact of adjuvant chemotherapy.

A phase 1 and randomized controlled phase 2 trial of the safety and efficacy of the combination of gemcitabine and docetaxel with ontuxizumab (MORAb-004) in metastatic soft-tissue sarcomas

Background

Ontuxizumab, a humanized monoclonal antibody, targets endosialin (tumor endothelial marker 1 [TEM‐1] or CD248), which is expressed on sarcoma cells and is believed to be involved in tumor angiogenesis. This is the first trial to evaluate ontuxizumab in patients with sarcoma.

Methods

Part 1 was an open‐label, dose‐finding, safety lead‐in: 4, 6, or 8 mg/kg with gemcitabine and docetaxel (G/D; 900 mg/m² gemcitabine on days 1 and 8 and 75 mg/m² docetaxel on day 8). In part 2, patients were randomized in a double‐blind fashion in 2:1 ratio to ontuxizumab (8 mg/kg) or a placebo with G/D. Randomization was stratified by 4 histological cohorts.

Results

In part 2 with 209 patients, no significant difference in progression‐free survival between ontuxizumab plus G/D (4.3 months; 95% confidence interval [CI], 2.7‐6.3 months) and the placebo plus G/D (5.6 months; 95% CI, 2.6‐8.3 months) was observed (P = .67; hazard ratio [HR], 1.07; 95% CI, 0.77‐1.49). Similarly, there was no significant difference in median overall survival between the 2 groups: 18.3 months for the ontuxizumab plus G/D group (95% CI, 16.2‐21.1 months) and 21.1 months for the placebo plus G/D group (95% CI, 14.2 months to not reached; P = .32; HR, 1.23; 95% CI, 0.82‐1.82). No significant differences between the treatment groups occurred for any efficacy parameter by sarcoma cohort. The combination of ontuxizumab plus G/D was generally well tolerated.

Conclusions

Ontuxizumab plus G/D showed no enhanced activity over chemotherapy alone in soft‐tissue sarcomas, whereas the safety profile of the combination was consistent with G/D alone.

Endosialin is involved in tumor blood vessel formation and is expressed on sarcoma tumor cells. This phase 1/2 randomized controlled trial shows that ontuxizumab, an endosialin‐directed monoclonal antibody, does not enhance efficacy in sarcomas when it is combined with chemotherapy (gemcitabine and docetaxel), although the combination is generally well tolerated.

A Pilot Trial of the Combination of Transgenic NY-ESO-1-reactive Adoptive Cellular Therapy with Dendritic Cell Vaccination with or without Ipilimumab

PURPOSE

Transgenic adoptive cell therapy (ACT) targeting the tumor antigen NY-ESO-1 can be effective for the treatment of sarcoma and melanoma. Preclinical models have shown that this therapy can be improved with the addition of dendritic cell (DC) vaccination and immune checkpoint blockade. We studied the safety, feasibility, and antitumor efficacy of transgenic ACT with DC vaccination, with and without CTLA-4 blockade with ipilimumab.

PATIENTS AND METHODS

Freshly prepared autologous NY-ESO-1-specific T-cell receptor (TCR) transgenic lymphocytes were adoptively transferred together with NY-ESO-1 peptide-pulsed DC vaccination in HLA-A2.1-positive subjects alone (ESO, NCT02070406) or with ipilimumab (INY, NCT01697527) in patients with advanced sarcoma or melanoma.

RESULTS

Six patients were enrolled in the ESO cohort, and four were enrolled in the INY cohort. Four out of six patients treated per ESO (66%), and two out of four patients treated per INY (50%) displayed evidence of tumor regression. Peripheral blood reconstitution with NY-ESO-1-specific T cells peaked within 2 weeks of ACT, indicating rapid in vivo expansion. Tracking of transgenic T cells to the tumor sites was demonstrated in on-treatment biopsies via TCR sequencing. Multiparametric mass cytometry of transgenic cells demonstrated shifting of transgenic cells from memory phenotypes to more terminally differentiated effector phenotypes over time.

CONCLUSIONS

ACT of fresh NY-ESO-1 transgenic T cells prepared via a short ex vivo protocol and given with DC vaccination, with or without ipilimumab, is feasible and results in transient antitumor activity, with no apparent clinical benefit of the addition of ipilimumab. Improvements are needed to maintain tumor responses.

Phase 1/2 study of epacadostat in combination with ipilimumab in patients with unresectable or metastatic melanoma

Background

Epacadostat is a potent inhibitor of the immunosuppressive indoleamine 2,3-dioxygenase 1 (IDO1) enzyme. We present phase 1 results from a phase 1/2 clinical study of epacadostat in combination with ipilimumab, an anti-cytotoxic T-lymphocyte-associated protein 4 antibody, in advanced melanoma (NCT01604889).

Methods

Only the phase 1, open-label portion of the study was conducted, per the sponsor’s decision to terminate the study early based on the changing melanoma treatment landscape favoring exploration of programmed cell death protein 1 (PD-1)/PD-ligand 1 inhibitor-based combination strategies. Such decision was not related to the safety of epacadostat plus ipilimumab. Patients received oral epacadostat (25, 50, 100, or 300 mg twice daily [BID]; 75 mg daily [50 mg am, 25 mg pm]; or 50 mg BID intermittent [2 weeks on/1 week off]) plus intravenous ipilimumab 3 mg/kg every 3 weeks.

Results

Fifty patients received ≥1 dose of epacadostat. As of January 20, 2017, 2 patients completed treatment and 48 discontinued, primarily because of adverse events (AEs) and disease progression (n = 20 each). Dose-limiting toxicities occurred in 11 patients (n = 1 each with epacadostat 25 mg BID, 50 mg BID intermittent, 75 mg daily; n = 4 each with epacadostat 50 mg BID, 300 mg BID). The most common immune-related treatment-emergent AEs included rash (50%), alanine aminotransferase elevation (28%), pruritus (28%), aspartate aminotransferase elevation (24%), and hypothyroidism (10%). Among immunotherapy-naive patients (n = 39), the objective response rate was 26% by immune-related response criteria and 23% by Response Evaluation Criteria in Solid Tumors version 1.1. No objective response was seen in the 11 patients who received prior immunotherapy. Epacadostat exposure was dose proportional, with clinically significant IDO1 inhibition at doses ≥25 mg BID.

Conclusions

When combined with ipilimumab, epacadostat ≤50 mg BID demonstrated clinical and pharmacologic activity and was generally well tolerated in patients with advanced melanoma.

Trial registration

ClinicalTrials.gov identifier, NCT01604889. Registration date, May 9, 2012, retrospectively registered.

Electronic supplementary material

The online version of this article (10.1186/s40425-019-0562-8) contains supplementary material, which is available to authorized users.

Patient (pt) experiences with avelumab in treatment-naive metastatic Merkel cell carcinoma (mMCC): Qualitative interview findings from a registrational clinical trial

90

Background: MCC is a rare, aggressive skin cancer with a poor prognosis. Avelumab is the only anti–PD-L1 monoclonal antibody approved for treatment of mMCC. This qualitative research embedded in a clinical trial aimed to explore pt experiences on treatment with avelumab. Methods: All treatment-naive pts with mMCC entering the registrational, open-label, multicenter trial to investigate the clinical activity and safety of avelumab were invited to participate in optional, semistructured, 30-min phone interviews at baseline (prior to study drug administration) and at weeks 13 and 25. Interviews were conducted by trained professionals, audio-recorded, transcribed, and analyzed using a qualitative software package, ATLAS.ti V7. Key concepts identified from the baseline interview for each pt were assessed during follow-up interviews. Results: A total of 29 pts (mean age, 71 y; 76% male) completed the baseline interview; 19 pts (6 in USA, 4 in France, 5 in Italy, 3 in Germany, 1 in Australia) had ≥1 follow-up interview. The baseline interviews revealed the negative psychological burden on pts living with a symptomless disease and the hope for avelumab to be a successful therapy. Over the course of the trial, most pts reported an increased or continued sense of hope and willingness to fight MCC. Pts who self-reported their disease to be improved (n=12) also reported being stable or experiencing improvements in their ability to do their daily activities and in their physical well-being and having more energy than before starting avelumab. They also reported worrying less and being optimistic. Six pts among the 7 who reported their condition as stable (n=4) or worsened (n=3) reported a worsening of their physical well-being. Nine pts reported fatigue/tiredness on the day of and the day after receiving the avelumab infusion. The reported baseline and longitudinal experiences were similar across pts from all countries. Conclusions: This qualitative study alongside a registrational trial showed that pts experienced perceptible benefits in their physical and psychological well-being following treatment success with avelumab in mMCC. Clinical trial information: NCT02155647 part B.

Healthcare resource utilization in first-line immunotherapies for patients with metastatic melanoma

137

Background: Immunotherapies (I/Os) have demonstrated improved overall survival vs. chemotherapy for patients (pts) with metastatic melanoma (MM). However, little is known about the comparative health care resource utilization (HCRU) among different I/Os. This study examined the real world HCRU across different I/Os: PD-1 inhibitors (pembrolizumab (PEM) or nivolumab (NIVO), PD-1), CTLA-4 inhibitor (ipilimumab, IPI), and combination of I/Os (IPI+NIVO). Methods: A retrospective observational study was conducted using a large US payer claims data. Adults with ≥2 claims for MM and ≥1 claim for metastasis were identified between 1/1/2012 and 6/30/2017 and followed through 9/30/2017. All pts had pharmacy and medical claims and ≥6 months pre-index enrollment. HCRU was calculated per pt per month (PPPM) and by percentages across PD-1, IPI, IPI+NIVO from Index date until the first occurrence of: change in regimen, end of continuous enrollment, or end of study period. Adjusted odds ratios (OR) for HCRU were estimated using logistic regressions to control for baseline patient characteristics. Results: On average, pts in the PD-1 cohort (n = 255) were older than those in IPI (n = 555) and IPI+NIVO (n = 88) cohorts (mean 68 vs 63 and 63, both p < 0.05) and had less brain metastasis (22% vs 34% and 31%, p < 0.05 and p = 0.11, respectively). During 1L therapy, fewer PD-1 pts had any hospitalization (HOSP, 25.9% vs 39.8% and 45.5%, both p < 0.05), fewer HOSPs PPPM (mean 0.06 vs 0.10 and 0.14, both p < 0.05), and fewer ER visits PPPM (mean 0.09 vs 0.13 and 0.18, both p < 0.05) compared to IPI and IPI+NIVO, respectively. Any 30-day re-HOSP and ER visits were numerically lower with PD-1 compared with IPI and IPI+NIVO, but not statistically significant (13.7% vs 19.1% and 18.2%; 40.0% vs 47.0% and 50.0% respectively). Adjusting for baseline characteristics, pts treated with IPI and IPI+NIVO were more likely to have a HOSP than PD-1s (OR = 2.10, 95% CI, 1.44-3.07; and 2.35; 95% CI, 1.32-4.12, both p < 0.01). Conclusions: Pts treated with IPI or IPI+NIVO had significantly increased odds of being hospitalized and higher HOSP and ER visits PPPM compared to PD-1s. Further studies are warranted to confirm these findings.

HSR19-095: Healthcare Resource Utilization and Costs in Patients Treated with Systemic Therapies in Metastatic Melanoma

Background: The treatment (tx) landscape for patients (pts) with metastatic melanoma (MM) has changed dramatically from systemic chemotherapy (chemo) to novel therapies, including targeted therapies (TT) and immunotherapies (IO mono- and combination therapy) in recent years. Healthcare resource utilization (HCRU) and cost data are needed to further evaluate tx in a value-based healthcare system. The study aimed to describe HCRU and total cost of care among first line (1L) US MM pts treated with IO, TT, or chemo. Methods: A retrospective observational study was conducted using a U.S. claims database. Adults with ≥2 claims for melanoma and ≥1 claim for metastasis between January 1, 2012 and June 30, 2017 were identified. Pts had pharmacy and medical enrollment ≥6 months pre and ≥3 months post 1L tx start. Per pt per month (PPPM) HCRU and costs were calculated by 1L tx drug class: PD-1, CTLA-4, CTLA-4+PD-1, mono-TT, combo-TT, and chemo. Adjusted odds ratios (OR) for HCRU were estimated by logistic regressions, and adjusted costs were estimated by generalized linear models to control for differences in pt characteristics across groups. Results: Among 1,599 MM pts (255 PD-1, 555 CTLA-4, 88 CTLA-4+PD-1, 210 mono-TT, 102 combo-TT, 389 chemo), mean age ranged from 59–68 years across tx groups, and the majority was male (62%). Any hospitalization during 1L was less frequent among PD-1 (26%) compared to 35%–46% of all other groups (all P<.05). CTLA-4, CTLA-4+PD-1, and combo-TT had increased odds of hospitalization compared to PD-1 (adjusted ORs: 2.10, 2.35, 2.15, respectively; all P<.05). Total adjusted PPPM costs were significantly lower for PD-1 compared to CTLA-4, CTLA-4+PD-1 and combo-TT and higher compared to mono-TT and chemo (Table 1). Conclusions: Hospitalizations represent an important healthcare resource for MM pts and were lowest among PD-1. Total monthly costs varied substantially across 1L regimens and were significantly lower in PD-1 compared to CTLA-4, CTLA-4+PD-1, and combo-TT. HCRU and costs differentiate 1L MM regimens.

Abstract P2-09-08: Imprime PGG, a novel innate immune modulator, combined with pembrolizumab in a phase 2 multicenter, open label study in chemotherapy-resistant metastatic triple negative breast cancer (TNBC)

Background: CPI monotherapy provides substantial clinical benefit to patients (pts) in multiple cancers, yet response rates are limited (˜15-30%) and fails to benefit the majority. In these pts there is limited or no ongoing T cell-based immune response. Imprime PGG (Imprime), a novel beta glucan derived from Saccharomyces, may expand the clinical benefit of CPI therapy by stimulating an anti-cancer immune response. Acting as a pathogen-associated molecularpattern (PAMP), Imprime enlists innate immune functions including cytotoxic effector mechanisms, reversal of immunosuppression and cross-talk with the adaptive immune system.Imprime-mediated innate immune activation requires formation of an immune complex with naturally-occurring anti-beta glucan antibodies (ABA); sufficient ABA levels is required for complex formation. Imprime is now being studied in combination with pembrolizumab (KEYTRUDA®,Pembro), a humanized mAb against PD-1 which has been previously studied in TNBC pts.

Methods: In this study of patients who previously failed chemotherapy for metastatic TNBC, Imprime is being used in combination with Pembro in a Simon 2 stage design. Asample size of 12 evaluable pts in Stage 1 was planned.Evaluable pts received at least one dose of study treatment (tx), had measurable disease at baseline per RECIST v1.1, had at least one post-baseline scan or discontinued tx as a result of progressive disease, death, or a tx-related adverse event before the first post-baseline scan.Pts received Imprime (4 mg/kg IV days 1, 8, 15 of each 3-week cycle) + Pembro 200 mg on D1 of each cycle. Criteria to advance to Stage 2 were ≤4 grade 3/4 AEs during the first tx cycle (other than infusion reactions) and ≥1 objective response. Study primary endpoints are ORR and safety; secondary endpoints are TTR, CRR, DoR, PFS, and OS. Exploratory endpoints include ORR and PFS per irRECIST. Biopsies and blood samples are being collected to assess tx impact on immune activating events at the tumor site and in the periphery.

Results: A review of efficacy and safety data was conducted at the end of Stage 1. Thirteen pts (12 evaluable) were enrolled into Stage 1. Safety review noted 2 grade 3 adverse events that met protocol definition of Stage 1 events (1 pt: cellulitis and 1 pt: pleural infusion; both unrelated to treatment). Two events lead to 2 pts discontinuing treatment (infusion reaction and pancreatitis) and only 1 autoimmune event was observed (pancreatitis). Observed efficacy responses in the evaluable pts included 1 complete response (CR; ongoing) and 2 partial responses (PR; ongoing). Secondary efficacy endpoints have not been assessed. Early translational results support proposed MOA and analysis of Stage 1 translational data is ongoing.

Conclusion: The use of Imprime with Pembro was well tolerated and met both safety and efficacy requirements to move forward with Stage 2 of the study. No significant safety concerns were identified in Stage 1. Further investigation is thus warranted and enrollment into Stage 2 is ongoing. Updated data will be presented.

Citation Format: O'Day S, Borges V, Chmielowski B, Rao R, Abu-Khalaf M, Stopeck A, Lowe J, Mattson P, Breuer K, Gargano M, Bose N, Uhlik M, Graff J, Chisamore M, Cox J, Osterwalder B. Imprime PGG, a novel innate immune modulator, combined with pembrolizumab in a phase 2 multicenter, open label study in chemotherapy-resistant metastatic triple negative breast cancer (TNBC) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-09-08.

A combination of irinotecan/cisplatinum and irinotecan/temozolomide or tumor-targeting Salmonella typhimurium A1-R arrest doxorubicin- and temozolomide-resistant myxofibrosarcoma in a PDOX mouse model

Myxofibrosarcoma (MFS) is the most common sarcomas in elderly patients and is either chemo-resistant or recurs with metastasis after chemotherapy. This recalcitrant cancer in need of improved treatment. We have established a patient-derived orthotopic xenograft (PDOX) of MFS. The MFS PDOX model was established in the biceps femoris of nude mice and randomized into 7 groups of 7 mice each: control; doxorubicin (DOX); pazopanib (PAZ); temozolomide (TEM); Irinotecan (IRN); IRN combined with TEM; IRN combined with cisplatinum (CDDP) and Salmonella typhimurium A1-R (S. typhimurium A1-R). Treatment was evaluated by relative tumor volume and relative body weight. The MFS PDOX models were DOX, PAZ, and TEM resistant. IRN combined with TEM and IRN combined with CDDP were most effective on the MFS PDOX. S. typhimurium A1-R arrested the MFS PDOX tumor. There was no significant body weight loss in any group. The present study suggests that the combination of IRN with either TEM or CDDP, and S. typhimurium have clinical potential for MFS.

Efficacy and Safety of First-line Avelumab Treatment in Patients With Stage IV Metastatic Merkel Cell Carcinoma: A Preplanned Interim Analysis of a Clinical Trial

Importance

Merkel cell carcinoma (MCC) is an aggressive skin cancer that is associated with poor survival outcomes in patients with distant metastatic disease. Results of part A of the JAVELIN Merkel 200 trial (avelumab in patients with Merkel cell carcinoma) showed that avelumab, an anti-programmed cell death ligand 1 (PD-L1) antibody, demonstrated efficacy in second-line or later treatment of patients with metastatic MCC (mMCC).

Objective

To evaluate the efficacy and safety of avelumab as first-line treatment for patients with distant mMCC.

Design, Setting, and Participants

JAVELIN Merkel 200 part B is an international, multicenter, single-arm, open-label clinical trial of first-line avelumab monotherapy. Eligible patients were adults with mMCC who had not received prior systemic treatment for metastatic disease. Patients were not selected for PD-L1 expression or Merkel cell polyomavirus status. Data were collected from April 15, 2016, to March 24, 2017, and enrollment is ongoing.

Interventions

Patients received avelumab, 10 mg/kg, by 1-hour intravenous infusion every 2 weeks until confirmed disease progression, unacceptable toxic effects, or withdrawal occurred.

Main Outcomes and Measures

Tumor status was assessed every 6 weeks and evaluated by independent review committee per Response Evaluation Criteria in Solid Tumors version 1.1. The primary end point was durable response, defined as an objective response with a duration of at least 6 months. Secondary end points include best overall response, duration of response, progression-free survival, safety, and tolerability.

Results

As of March 24, 2017, 39 patients were enrolled (30 men and 9 women; median age, 75 years [range, 47-88 years]), with a median follow-up of 5.1 months (range, 0.3-11.3 months). In a preplanned analysis, efficacy was assessed in 29 patients with at least 3 months of follow-up; the confirmed objective response rate was 62.1% (95% CI, 42.3%-79.3%), with 14 of 18 responses (77.8%) ongoing at the time of analysis. In responding patients, the estimated proportion with duration of response of at least 3 months was 93% (95% CI, 61%-99%); duration of response of at least 6 months, 83% (95% CI, 46%-96%). First-line avelumab treatment was generally well tolerated, and no treatment-related deaths or grade 4 adverse events occurred.

Conclusions and Relevance

High rates of response to first-line avelumab therapy in patients with distant mMCC build on previously reported antitumor activity after second-line or later treatment, and maturing progression-free survival data suggest that responses are durable. These data further support avelumab's approval in the United States and European Union and use as a standard-of-care treatment for mMCC.

Trial Registration

clinicaltrials.gov Identifier: NCT02155647.

Patterns of sensitivity to a panel of drugs are highly individualised for undifferentiated/unclassified soft tissue sarcoma (USTS) in patient-derived orthotopic xenograft (PDOX) nude-mouse models

Undifferentiated/unclassified soft tissue sarcoma (USTS) is a recalcitrant disease; therefore, precise individualised therapy is needed. Toward this goal, we previously established patient-derived orthotopic xenograft (PDOX) models of USTS in nude mice. Here, we determined the extent of uniqueness of drug response in a panel on USTS PDOX models from 5 different patients. We previously showed that 3 of the 5 patients were resistant to doxorubicin (DOX) despite DOX being first-line therapy. Two weeks after orthotopic tumour implantation, PDOX mouse models were randomised into five groups: untreated control, DOX, gem-citabine/docetaxel (GEM/DOC), pazopanib (PAZ), temozolomide (TEM). Three PDOX cases were completely resistant to DOX. TEM had high efficacy for 4 USTS PDOX models, including DOX-resistant cases. GEM/DOC and PAZ were effective in three USTS PDOX. One case was completely resistant to TEM. Two cases were completely resistant to PAZ. The results showed the drug sensitivity pattern for each USTS PDOX was highly individualised and that at least one effective drug could be found for each. The PDOX model could be effective in precise individualised drug sensitivity testing which is especially important for heterogeneous cancers such as USTS, and can give the patient a greater chance to be treated with an effective drug.

Direct costs associated with adverse events of systemic therapies for advanced melanoma: Systematic literature review

BACKGROUND

Treatments for advanced melanoma are associated with different adverse events (AEs), which may be costly to manage. This study aimed to evaluate direct costs associated with managing treatment-related AEs for advanced melanoma through a systematic literature review.

METHODS

Systematic searches were conducted of the PubMed, Embase, Cochrane, BIOSIS, and EconLit medical literature databases to identify studies providing estimates of direct costs and health care resource utilization for the management of AEs of melanoma treatments, published between January 1, 2007, and February 23, 2017. Gray literature searches also were conducted. Studies reporting direct costs for patients with advanced melanoma that were published in English between 2007 and 2017 were eligible. Studies were systematically screened in 2 phases by 2 independent reviewers. Study design details and data on direct costs by country were extracted.

RESULTS

Seven studies evaluating the cost of AEs in patients with advanced melanoma were included; most estimated the costs for grade 3 or 4 events. In a United States study, monthly AE costs constituted 36.9% of overall health care costs for dacarbazine, 30.3% for paclitaxel, 9.2% for temozolomide, 6.4% for vemurafenib, and 4.0% for ipilimumab. A multicountry study found the greatest cost per event to be for grade 3 or 4 AEs associated with ipilimumab, including colitis (A$1471 [Australia]-&OV0556;3313 [France]) and diarrhea (£2836 [United Kingdom]), and chemotherapy (neutropenia/leukopenia in Germany [&OV0556;1744] and Italy [&OV0556;804]). Across studies, cost drivers for the most expensive AEs to manage were requiring hospitalization or use of expensive outpatient medications and/or procedures (eg, erythropoietin and blood transfusions for anemia). Some currently available therapies were not available during the research period, and their associated AEs are not reflected. Results may not be comparable across countries. For some studies, resource-use estimates reflect practice patterns from a limited number of centers, limiting generalizability.

CONCLUSION

Costs for managing each type of AE associated with the treatment of advanced melanoma are substantial. Effective treatments with improved safety profiles may help reduce total AE management costs.

Abstract CT008: A pilot trial of the combination of transgenic NY-ESO-1-reactive adoptive cellular therapy with dendritic cell vaccination with or without ipilimumab in patients with sarcoma and melanoma

Background: Transgenic adoptive cell therapy (ACT) targeting the tumor antigen NY-ESO-1 can be effective for the treatment of sarcoma and melanoma. Preclinical models have shown that this therapy can be improved with the addition of dendritic cell (DC) vaccination and immune checkpoint blockade. In this study, we report the results of the safety, feasibility, and antitumor efficacy of this approach alone and in combination with the CTLA-4 blockade with ipilimumab.

Methods: NY-ESO-1 specific T-cell receptor (TCR) transgenic lymphocytes were adoptively transferred together with NY-ESO-1 peptide-pulsed DC vaccination in HLA-A*0201-positive subjects with (ESO, NCT02070406) or without ipilimumab (INY, NCT01697527) in patients with advanced sarcoma and melanoma under Investigator New Drug IND#15167. Patients received autologous retrovirally TCR-transduced T cells following a lymphodepleting preparative chemotherapy regimen. NY-ESO-1157-165 peptide-pulsed autologous DCs were administered on Days 1, 14 and 30, and low-dose IL-2 was given twice daily for 7-14 days. In the INY cohort, ipilimumab (1mg/kg) was given on day 0 or 1, and every three weeks for a maximum of four doses. Response rates were evaluated by RECIST.

Results: Four patients with synovial sarcoma, two patients with melanoma, one patient with osteosarcoma, one patient with liposarcoma, and one patient with malignant peripheral nerve sheath tumor were enrolled into these cohorts. Two patients (one treated per ESO, and another treated per INY) experienced cytokine release syndrome requiring hospitalization. Patients treated per INY had significantly higher serum levels of the cytokine FLT-3L. Two out of four patients treated per INY, and four out of six patients treated per ESO demonstrated an objective clinical response by day 30. One patient treated per ESO (17%) has had an ongoing complete response for 3 years. One patient was treated per ESO and, following disease progression after an objective clinical response, was subsequently enrolled in INY. TCR sequencing of dextramer-positive cells demonstrated that the NY-ESO TCR integrated across a highly polyclonal population of endogenous TCR clonotypes. Tracking of transgenic T cells to the tumor and acquisition of PD-1 expression was demonstrated by TCR sequencing and immunohistochemistry of on-treatment biospies, respectively.

Conclusions: ACT of fresh NY-ESO-1 transgenic T cells prepared via a short ex vivo protocol and given with DC vaccination and low dose IL-2, with or without ipilimumab, is feasible and results in transient antitumor activity, with no apparent clinical benefit of the addition of ipilimumab. Improvements are needed to maintain tumor responses.

Citation Format: Theodore S. Nowicki, Beata Berent-Maoz, Rong Rong Huang, Xiaoyan Wang, Gardenia Cheung-Lau, Paula Kaplan-Lefko, Paula Cabrera, Justin Tran, Ignacio Baselga Carretero, Catherine S. Grasso, Siwen Hu-Lieskovan, Bartosz Chmielowski, Begoña Comin-Anduix, Arun Singh, Antoni Ribas. A pilot trial of the combination of transgenic NY-ESO-1-reactive adoptive cellular therapy with dendritic cell vaccination with or without ipilimumab in patients with sarcoma and melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr CT008.

Selumetinib in Combination With Dacarbazine in Patients With Metastatic Uveal Melanoma: A Phase III, Multicenter, Randomized Trial (SUMIT)

Purpose Uveal melanoma is the most common primary intraocular malignancy in adults with no effective systemic treatment option in the metastatic setting. Selumetinib (AZD6244, ARRY-142886) is an oral, potent, and selective MEK1/2 inhibitor with a short half-life, which demonstrated single-agent activity in patients with metastatic uveal melanoma in a randomized phase II trial. Methods The Selumetinib (AZD6244: ARRY-142886) (Hyd-Sulfate) in Metastatic Uveal Melanoma (SUMIT) study was a phase III, double-blind trial ( ClinicalTrial.gov identifier: NCT01974752) in which patients with metastatic uveal melanoma and no prior systemic therapy were randomly assigned (3:1) to selumetinib (75 mg twice daily) plus dacarbazine (1,000 mg/m2 intravenously on day 1 of every 21-day cycle) or placebo plus dacarbazine. The primary end point was progression-free survival (PFS) by blinded independent central radiologic review. Secondary end points included overall survival and objective response rate. Results A total of 129 patients were randomly assigned to receive selumetinib plus dacarbazine (n = 97) or placebo plus dacarbazine (n = 32). In the selumetinib plus dacarbazine group, 82 patients (85%) experienced a PFS event, compared with 24 (75%) in the placebo plus dacarbazine group (median, 2.8 v 1.8 months); the hazard ratio for PFS was 0.78 (95% CI, 0.48 to 1.27; two-sided P = .32). The objective response rate was 3% with selumetinib plus dacarbazine and 0% with placebo plus dacarbazine (two-sided P = .36). At 37% maturity (n = 48 deaths), analysis of overall survival gave a hazard ratio of 0.75 (95% CI, 0.39 to 1.46; two-sided P = .40). The most frequently reported adverse events (selumetinib plus dacarbazine v placebo plus dacarbazine) were nausea (62% v 19%), rash (57% v 6%), fatigue (44% v 47%), diarrhea (44% v 22%), and peripheral edema (43% v 6%). Conclusion In patients with metastatic uveal melanoma, the combination of selumetinib plus dacarbazine had a tolerable safety profile but did not significantly improve PFS compared with placebo plus dacarbazine.

Individualized doxorubicin sensitivity testing of undifferentiated soft tissue sarcoma (USTS) in a patient-derived orthotopic xenograft (PDOX) model demonstrates large differences between patients

Doxorubicin (DOX) is often first-line treatment of undifferentiated/unclassified soft tissue sarcoma (USTS). However, the DOX response rate for USTS patients is low. Individualized precision-medicine technology that could identify DOX responders as well as non-responders would be of high value to cancer patients. In the present study, we established 5 patient-derived orthotopic xenograft (PDOX) nude mouse models from 5 USTS patients and evaluated the efficacy of DOX in each PDOX model. USTS's were grown orthotopically in the right thigh of nude mice to establish the PDOX models. Two weeks after implantation, the mouse models were randomized into two groups of 8 mice each: untreated control; and DOX (3 mg/kg, i.p., once a week for 2 weeks). DOX showed significant growth inhibition in only 2 USTS PDOX models out of 5 (p = 0.0054, p = 0.0055, respectively) on day 14 after initiation. DOX was ineffective in the other 3 PDOX models. However, even in the DOX-sensitive cases, DOX could not regress the PDOX tumors responding to treatment. The present study has important implications since this is the first in vivo study to compare the DOX sensitivity for USTS on multiple patient tumors. We showed that only two of five USTS were responsive to DOX, despite DOX being first line chemotherapy for USTS. The 3 resistant cases should not be treated with DOX clinically, in order to spare the patients' unnecessary toxicity. This PDOX model is useful for precise individualized drug sensitivity testing, especially for rare heterogeneous recalcitrant sarcomas such as USTS.

Targeting methionine with oral recombinant methioninase (o-rMETase) arrests a patient-derived orthotopic xenograft (PDOX) model of BRAF-V600E mutant melanoma: implications for chronic clinical cancer therapy and prevention

The elevated methionine (MET) use by cancer cells is termed MET dependence and may be the only known general metabolic defect in cancer. Targeting MET by recombinant methioninase (rMETase) can arrest the growth of cancer cells in vitro and in vivo. We previously reported that rMETase, administrated by intra-peritoneal injection (ip-rMETase), could inhibit tumor growth in a patient-derived orthotopic xenograft (PDOX) model of a BRAF-V600E mutant melanoma. In the present study, we compared ip-rMETase and oral rMETase (o-rMETase) for efficacy on the melanoma PDOX. Melanoma PDOX nude mice were randomized into four groups of 5 mice each: untreated control; ip-rMETase (100 units, i.p., 14 consecutive days); o-rMETase (100 units, p.o., 14 consecutive days); o-rMETase+ip-rMETase (100 units, p.o.+100 units, i.p., 14 consecutive days). All treatments inhibited tumor growth on day 14 after treatment initiation, compared to untreated control (ip-rMETase, p<0.0001; o-rMETase, p<0.0001; o-rMETase+ip-rMETase, p<0.0001). o-rMETase was significantly more effective than ip-rMETase (p = 0.0086). o-rMETase+ip-rMETase was significantly more effective than either mono-therapy: ip-rMETase, p = 0.0005; or o-rMETase, p = 0.0367. The present study is the first demonstrating that o-rMETase is effective as an anticancer agent. The results of the present study indicate the potential of clinical development of o-rMETase as an agent for chronic cancer therapy and for cancer prevention and possibly for life extension since dietary MET reduction extends life span in many animal models.

Tumor-targeting Salmonella typhimurium A1-R combined with temozolomide regresses malignant melanoma with a BRAF-V600E mutation in a patient-derived orthotopic xenograft (PDOX) model

Melanoma is a recalcitrant disease in need of transformative therapuetics. The present study used a patient-derived orthotopic xenograft (PDOX) nude-mouse model of melanoma with a BRAF-V600E mutation to determine the efficacy of temozolomide (TEM) combined with tumor-targeting Salmonella typhimurium A1-R. A melanoma obtained from the right chest wall of a patient was grown orthotopically in the right chest wall of nude mice to establish a PDOX model. Two weeks after implantation, 40 PDOX nude mice were divided into 4 groups: G1, control without treatment (n = 10); G2, TEM (25 mg/kg, administrated orally daily for 14 consecutive days, n = 10); G3, S. typhimurium A1-R (5 × 10⁷ CFU/100 μl, i.v., once a week for 2 weeks, n = 10); G4, TEM combined with S. typhimurium A1-R (25 mg/kg, administrated orally daily for 14 consecutive days and 5 × 10⁷ CFU/100 μl, i.v., once a week for 2 weeks, respectively, n = 10). Tumor sizes were measured with calipers twice a week. On day 14 from initiation of treatment, all treatments significantly inhibited tumor growth compared to untreated control (TEM: p < 0.0001; S. typhimurium A1-R: p < 0.0001; TEM combined with S. typhimurium A1-R: p < 0.0001). TEM combined with S. typhimurium A1-R was significantly more effective than either S. typhimurium A1-R (p = 0.0004) alone or TEM alone (p = 0.0017). TEM combined with S. typhimurium A1-R could regress the melanoma in the PDOX model and has important future clinical potential for melanoma patients.

A phase 2 study of ontuxizumab, a monoclonal antibody targeting endosialin, in metastatic melanoma

Objectives Ontuxizumab (MORAB-004) is a first-in-class monoclonal antibody that interferes with endosialin function, which is important in tumor stromal cell function, angiogenesis, and tumor growth. This Phase 2 study evaluated the 24-week progression-free survival (PFS) value, pharmacokinetics, and tolerability of 2 doses of ontuxizumab in patients with metastatic melanoma. Patients and methods Patients with metastatic melanoma and disease progression after receiving at least 1 prior systemic treatment were randomized to receive ontuxizumab (2 or 4 mg/kg) weekly, without dose change, until disease progression. Results Seventy-six patients received at least 1 dose of ontuxizumab (40 received 2 mg/kg, 36 received 4 mg/kg). The primary endpoint, 24-week PFS value, was 11.4% (95% Confidence Interval [CI]: 5.3%-19.9%) for all patients (13.5% for 2 mg/kg and 8.9% for 4 mg/kg). The median PFS for all patients was 8.3 weeks (95% CI: 8.1-12.3 weeks). One patient receiving 4 mg/kg had a partial response, as measured by Response Evaluation Criteria in Solid Tumors v1.1. Twenty-seven of 66 response evaluable patients (40.9%) had stable disease. The median overall survival was 31.0 weeks (95% CI: 28.3-44.0 weeks). The most common adverse events overall were headache (55.3%), fatigue (48.7%), chills (42.1%), and nausea (36.8%), mostly grade 1 or 2. Conclusions Ontuxizumab at both doses was well tolerated. The 24-week PFS value was 11.4% among all ontuxizumab-treated patients. The overall response rate was 3.1% at the 4 mg/kg dose, with clinical benefit achieved in 42.4% of response evaluable patients. Efficacy of single-agent ontuxizumab at these doses in melanoma was low.

A randomized phase 2 study of nivolumab monotherapy versus nivolumab combined with ipilimumab in patients with metastatic or unresectable gastrointestinal stromal tumor (GIST)

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Background: The therapy with tyrosine kinase inhibitors changed the prognosis of patients with advanced GIST. Unfortunately, most of the tumors become resistant to therapy and patients succumb to the disease. New therapies for this patient population are needed. Here we report interim analyses of safety and efficacy in advanced GIST patients treated with immunotherapy. Methods: Patients with advanced/metastatic GIST progressing on at least imatinib were enrolled on a randomized, parallel group, unblinded phase 2 trial of either nivolumab(nivo) (240 mg Q2wks) or nivo (240 mg Q2wks) with ipilimumab(ipi) (1mg/kg Q6wks) for up to 2 years. The primary endpoint was the objective response rate (ORR) of nivo alone or nivo + ipi by RECIST 1.1 criteria. Patients were randomized 1:1 and the response was assessed every 8 weeks. With a sample size of 20 per group, an exact binomial test with a nominal 0.050 one-sided significance level will have 82% power to detect the difference between the null hypothesis response rate 1.5% and the alternative response rate of 15%. Secondary objectives are to ascertain the PFS, CBR, RR by Choi criteria and safety. Blood and biopsies are also being collected. Results: To date, 14 patients (median # of prior therapies: 4) have started on trial and 8 remain on treatment. In the nivo only arm, 3/7 patient had SD for a CBR of 42.8 %. The median PFS of the nivo arm was 8 weeks. In the nivo + ipi arm, 1/5(20%) patients had a PR and 1/5 have SD for a CBR of 40%; 2 patients were censored. The median PFS of the nivo + ipi arm was 8.43 weeks. 1 patient in the nivo arm had grade 3 fatigue and 1 patient in the nivo + ipi arm had grade 3 diarrhea. Pretreatment biopsies have been obtained in all patients and blood has been collected on all patients for correlative analysis. Conclusions: In a heavily pretreated GIST population, durable responses and disease control were observed. To date, the drugs have been well tolerated and no new safety signals have been observed in this disease state. Clinical trial information: NCT02880020.

Endocrinopathies with use of cancer immunotherapies

BACKGROUND

Immunomodulatory therapies, including CTLA-4 and PD-1 inhibitors, provide a directed attack against cancer cells by preventing T cell deactivation. However, these drugs also prevent the downregulation of auto-reactive T cells, resulting in immune-related adverse events (IRAEs). Reports show a varied incidence of endocrine IRAEs, ranging from 0% to 63%.

OBJECTIVE

To describe the frequency and clinical characteristics of endocrine IRAEs in patients taking cancer immunomodulatory therapies.

DESIGN

Retrospective cohort study.

PATIENTS

A total of 388 patients aged ≥18 years who were prescribed ipilimumab, nivolumab and/or pembrolizumab between 2009 and 2016 at our institution.

MEASUREMENTS

Biochemical criteria were used to define endocrine IRAEs, including thyroid, pituitary, pancreas and adrenal dysfunction, following use of immunomodulatory therapies.

RESULTS

Fifty endocrine IRAEs occurred in our cohort, corresponding to a rate of 12.9%. The most common endocrine IRAEs were thyroid dysfunction (11.1%), with a lower incidence of pituitary dysfunction (1.8% of patients).

CONCLUSIONS

Over 12% of patients receiving ipilimumab, nivolumab and/or pembrolizumab in our study sample developed an endocrine IRAE. Patients who undergo treatment with immunomodulatory therapies should be monitored for the development of endocrine IRAEs.

LXR/ApoE Activation Restricts Innate Immune Suppression in Cancer

Therapeutic harnessing of adaptive immunity via checkpoint inhibition has transformed the treatment of many cancers. Despite unprecedented long-term responses, most patients do not respond to these therapies. Immunotherapy non-responders often harbor high levels of circulating myeloid-derived suppressor cells (MDSCs)-an immunosuppressive innate cell population. Through genetic and pharmacological approaches, we uncovered a pathway governing MDSC abundance in multiple cancer types. Therapeutic liver-X nuclear receptor (LXR) agonism reduced MDSC abundance in murine models and in patients treated in a first-in-human dose escalation phase 1 trial. MDSC depletion was associated with activation of cytotoxic T lymphocyte (CTL) responses in mice and patients. The LXR transcriptional target ApoE mediated these effects in mice, where LXR/ApoE activation therapy elicited robust anti-tumor responses and also enhanced T cell activation during various immune-based therapies. We implicate the LXR/ApoE axis in the regulation of innate immune suppression and as a target for enhancing the efficacy of cancer immunotherapy in patients.