Lower Objective Response Rate Research Articles

The Role of the EZH2 and H3K27me3 Expression as a Predictor of Clinical Outcomes in Salivary Duct Carcinoma Patients: A Large-Series Study With Emphasis on the Relevance to the Combined Androgen Blockade and HER2-Targeted Therapy.

ObjectiveSalivary duct carcinoma (SDC) is a highly aggressive and uncommon tumor arising not only de novo but also in pleomorphic adenoma. Androgen receptor (AR)- and HER2-targeted therapy have recently been introduced for SDC as promising treatment options; however, no predictive biomarkers have yet been established. EZH2 and H3K27me3 are closely linked to the development and progression of various cancers, and EZH2 is also expected to be a desirable therapeutic target. We therefore explored the clinicopathological and prognostic implications of EZH2 and H3K27me3 in a large cohort of SDC patients, focusing on their impact on the therapeutic efficacy of AR- or HER2-targeted therapy.Materials and MethodsThe EZH2 and H3K27me3 immunohistochemical expression and EZH2 Y646 gain-of-function mutation status were examined in 226 SDCs, and the relationship with the clinicopathological factors as well as clinical outcomes were evaluated within the three groups depending on the treatment: AR-targeted (combined androgen blockade with leuprorelin acetate and bicalutamide; 89 cases), HER2-targeted (trastuzumab and docetaxel; 42 cases), and conventional therapy (112 cases).ResultsEZH2 and H3K27me3 were variably immunoreactive in most SDCs. A positive correlation was found between the expression of EZH2 and H3K27me3. The EZH2 expression in the SDC component was significantly higher than that in the pre-existing pleomorphic adenoma component. EZH2 Y646 was not identified in any cases. EZH2-high cases more frequently had an advanced clinical stage and aggressive histological features than EZH2-low cases. An EZH2-high status in patients treated with AR-targeted therapy was associated with a significantly shorter progression-free and overall survival as well as a lower objective response rate and clinical benefit rate. In addition, a H3K27me3-high status in patients treated with AR-targeted therapy was related to a shorter overall survival. Conversely, there was no association between the EZH2 and H3K27me3 expression and the clinical outcomes in the conventional or HER2-targeted therapy groups.ConclusionsA high expression of EZH2 and H3K27me3 in SDC might be a predictor of a poor efficacy of AR-targeted therapy. Our data provide new insights into the role of EZH2 and H3K27me3 in therapeutic strategies for SDC.

The Systemic Inflammatory Response Identifies Patients with Adverse Clinical Outcome from Immunotherapy in Hepatocellular Carcinoma.

Simple SummaryThe investigation of predictive and prognostic markers is pivotal in patients affected by hepatocellular carcinoma treated with immune-checkpoint-inhibitors. Inflammation has a central role in hepatocellular carcinoma development and progression; however, its role in influencing outcomes in the context of immunotherapy has not been fully elucidated yet. In the following study, we investigated the prognostic role of bloods derived inflammatory markers and we found that they predict survival and response of patients treated with immunotherapy for advanced hepatocellular carcinoma.Systemic inflammation is a hallmark of cancer, and it has a pivotal role in hepatocellular carcinoma (HCC) development and progression. We conducted a retrospective study including 362 patients receiving immune check-point inhibitors (ICIs) across three continents, evaluating the influence of neutrophiles to lymphocytes ratio (NLR), platelets to lymphocytes ratio (PLR), and prognostic nutritional index (PNI) on overall (OS), progression free survival (PFS), and radiologic responses. In our 362 patients treated with immunotherapy, median OS and PFS were 9 and 3.5 months, respectively. Amongst tested inflammatory biomarkers, patients with NLR ≥ 5 had shorter OS (7.7 vs. 17.6 months, p < 0.0001), PFS (2.1 vs. 3.8 months, p = 0.025), and lower objective response rate (ORR) (12% vs. 22%, p = 0.034); similarly, patients with PLR ≥ 300 reported shorter OS (6.4 vs. 16.5 months, p < 0.0001) and PFS (1.8 vs. 3.7 months, p = 0.0006). NLR emerged as independent prognostic factors for OS in univariate and multivariate analysis (HR 1.95, 95%CI 1.45–2.64, p < 0.001; HR 1.73, 95%CI 1.23–2.42, p = 0.002) and PLR remained an independent prognostic factor for both OS and PFS in multivariate analysis (HR 1.60, 95%CI 1.6–2.40, p = 0.020; HR 1.99, 95%CI 1.11–3.49, p = 0.021). Systemic inflammation measured by NLR and PLR is an independent negative prognostic factor in HCC patients undergoing ICI therapy. Further studies are required to understand the biological mechanisms underlying this association and to investigate the predictive significance of circulating inflammatory biomarkers in HCC patients treated with ICIs.

Soluble PD-L1 as a predictive biomarker in lung cancer: a systematic review and meta-analysis.

Background: We performed a meta-analysis to evaluate the association between soluble PD-L1 (sPD-L1)and survival outcomes and treatment response in lung cancer. Methods & methods: Eligible studies were obtained by searching PubMed, EMBASE and Web of Science. Pooled effect estimates were calculated for overall survival (OS), progression-free survival (PFS) and objective response rate (ORR). Results: Twelve eligible studies with 1188 lung cancer patients were included. High sPD-L1 was significantly associated with worse OS (hazard ratio [HR]=2.20;95% CI: 1.59-3.05;p<0.001) and PFS (HR=2.42;95% CI: 1.72-3.42;p<0.001) in patients treated with immune checkpoint inhibitors (ICIs). Meanwhile, high sPD-L1 predicted worse OS (HR=1.60;95% CI: 1.31-1.96;p<0.001) and lower ORR (odds ratio=0.52;95% CI: 0.35-0.80;p=0.002) in patients treated with non-ICI therapies. Conclusion: sPD-L1 is a potential predictive biomarker of lung cancer.

Surgical Conversion for Initially Unresectable Locally Advanced Hepatocellular Carcinoma Using a Triple Combination of Angiogenesis Inhibitors, Anti-PD-1 Antibodies, and Hepatic Arterial Infusion Chemotherapy: A Retrospective Study.

BackgroundRecent research has shown that selected patients with initially unresectable hepatocellular carcinoma (HCC) are able to achieve conversion to resectable disease through systemic or local therapy. Combination regimens comprised of drugs with different mechanisms of action have shown better outcomes than single-drug or single-approach-based treatments; however, to date, combination regimens investigated as part of conversion therapy strategies have been two drug combinations with reported issues of relatively low surgical conversion and objective response rates. In this study, we investigated the efficacy and safety of triple combination therapy with angiogenesis inhibitors, programmed death-1 inhibitors and hepatic arterial infusion chemotherapy for surgical conversion of advanced HCC.MethodsThis was a single-center, retrospective, single-arm study of patients with unresectable HCC who received at least one cycle of triple combination therapy with an oral anti-angiogenic drug, programmed death-1 inhibitors and hepatic arterial infusion chemotherapy between August 2019 and August 2020. Endpoints included the overall response rate (ORR), surgical conversion rate, time to response and safety. Treatment response was assessed using the modified Response Evaluation Criteria in Solid Tumors (mRECIST) and RECIST v1.1.ResultsIn total, 34 patients were included in this study, of whom 25 completed treatment evaluation. The best ORR was 96.0% (24/25); 48.0% (n = 12) had a complete response, 48.0% (n = 12) had a partial response, and 4.0% (n = 1) had stable disease. The median time to response was 50.5 (95% CI, 31.02–64.00) days and the surgical conversion rate was 60% (15/25). Of the 25 patients, 56.0% (n = 14) received surgical resection and 28.0% (n = 7) had a pathologic complete response. Toxic side effects were manageable.ConclusionA triple combination therapy regimen of angiogenesis inhibitors, programmed death-1 inhibitors and hepatic arterial infusion chemotherapy showed significant therapeutic effect with an extremely high surgical conversion rate in patients with initially unresectable HCC.

Efficacy and Safety of PD-1 Inhibitor Plus Rituximab in Patients with Relapsed or Refractory Diffuse Large B-Cell Lymphoma

Background:Patients with relapsed or refractory diffuse large B-cell lymphoma (r/r DLBCL) who are ineligible for or progressed from autologous stem-cell transplantation have poor outcomes and few treatment options. Programmed cell death-1 (PD-1) inhibitor monotherapy has limited efficacy in pretreated DLBCL. Previous study has demonstrated that pembrolizumab plus R-CHOP was effective and safe as first-line treatment in patients with DLBCL and in vitro data suggests that rituximab acts partly via antibody-dependent cellular cytotoxicity, which may be enhanced by programmed cell death-1 (PD-1) blockade. Here, we report the preliminary results of a real-world, single-arm study investigating efficacy and safety of PD-1 inhibitor plus rituximab for r/r DLBCL.Methods:This is a real-world, single-center, single-arm study enrolling patients who received at least one dose of PD-1 inhibitor combined with rituximab as salvage therapeutic regimen after R-CHOP treatment in Cancer Hospital, Chinese Academy of Medical Science & Peking Union Medical College. Eligible patients received PD-inhibitors in combination with rituximab (375 mg/m2, q3w) for 6 cycles followed by maintenance therapy of PD-1 inhibitors plus rituximab (q8w) for 6 cycles until unacceptable toxicity, disease progression, death, or completion of 2-year treatment. The outcomes included objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), overall survival (OS) and safety. Responses were assessed by Lugano 2014 criteria, and PD-L1 staining (22C3) was performed at a validated central laboratory. Genomic analysis was performed including next generation sequencing (NGS) based sequence variant detection, copy number analysis and structural variant detection.Results:Between Oct 16, 2018, and May 10, 2021, 34 patients were enrolled and received at least one dose of both PD-1 inhibitor including toripalimab (n=24), pembrolizumab (n=3), nivolumab (n=3) and sintilimab (n=4), combined with rituximab. Key baseline characteristics included median age 56.5 (range 20-78) years; stage III/IV disease 58.8%; elevated LDH 41.2%; IPI ≥3 47.1%; median number of prior treatment regimen 2 (range 1-4); primary chemotherapy-refractory disease after R-CHOP 73.5%; median interval from last rituximab administration 5 (range 0.7-26) months. Histology included 30 DLBCL NOS (88.2%; 11 GCB, 19 non-GCB by Han's algorithm), 4 primary mediastinal B-cell lymphoma (PMBCL; 11.8%). Patients received a median of four (range 1-24) doses of PD-1 inhibitor and rituximab. Eight patients (6 DLBCL-NOS, 2 PMBCL) remained on treatment at the time of data cutoff on Jul 5, 2021.With a median follow-up of 21.3 months (95% CI: 9.6-24.2), 16 (53.3%; 95% CI: 34.3%-71.7%) of 30 patients with DLBCL-NOS had an objective response, with 2 (6.7%) having a complete response and 14 (46.7%) achieving a partial response. The median DOR was 16.8 (95%CI: 2.8-NR) months. The median PFS was 2.9 (95%CI: 1.5-18.5) months, and median OS was 25.3 (95%CI: 9.9-NR) months. The 1-year PFS and OS rates were 34.1% (95%CI: 17.3%-51.8%) and 73.6% (95%CI: 49.8%-87.4%), respectively. All of 4 PMBCL cases achieved CR, and their PFS were 21.2, 21.6, 22.9 and 29.2 months, respectively. Overall, 19 of 34 patients had available baseline biopsy samples for NGS analysis. Patients with TET2 mutations had higher ORR (100% versus 31.3%, p=0.058) and longer PFS (NR versus 1.6 months, p=0.019) while patients with β2-MG mutations had lower ORR (0% versus 53.3%, p=0.1) and shorter PFS (1.0 versus 2.8 months, p=0.0025). In addition, patients with BCL2 alteration/amplification/rearrangement had inferior OS than those BCL2 wild-type patients (5.0 versus 17.4 months, p=0.024). PD-L1 expression at baseline had no impact on response and survival. Most treatment-related adverse events were grade 1-2 including rash and neutropenia. Treatment was discontinued in 3 patients (2 interstitial pneumonia and 1 hypophysitis).Conclusion:PD-1 inhibitor combined with rituximab was effective and well tolerated in r/r DLBCL, achieving promising ORR and long-term remission. Further investigation is warranted. DisclosuresNo relevant conflicts of interest to declare.

Large-scale genomic sequencing reveals adaptive opportunity of targeting mutated-PI3Kα in early and advanced HER2-positive breast cancer.

BackgroundFew studies have discussed the contradictory roles of mutated‐PI3Kα in HER2‐positive (HER2+) breast cancer. Thus, we characterised the adaptive roles of PI3Kα mutations among HER2+ tumour progression.MethodsWe conducted prospective clinical sequencing of 1923 Chinese breast cancer patients and illustrated the clinical significance of PIK3CA mutations in locally advanced and advanced HER2+ cohort. A high‐throughput PIK3CA mutations‐barcoding screen was performed to reveal impactful mutation sites in tumour growth and drug responses.Results PIK3CA mutations acted as a protective factor in treatment‐naïve patients; however, advanced/locally advanced patients harbouring mutated‐PI3Kα exhibited a higher progressive disease rate (100% vs. 15%, p = .000053) and a lower objective response rate (81.7% vs. 95.4%, p = .0008) in response to trastuzumab‐based therapy. Meanwhile, patients exhibiting anti‐HER2 resistance had a relatively high variant allele fraction (VAF) of PIK3CA mutations; we defined the VAF > 12.23% as a predictor of poor anti‐HER2 neoadjuvant treatment efficacy. Pooled mutations screen revealed that specific PI3Kα mutation alleles mediated own biological effects. PIK3CA functional mutations suppressed the growth of HER2+ cells, but conferred anti‐HER2 resistance, which can be reversed by the PI3Kα‐specific inhibitor BYL719.ConclusionsWe proposed adaptive treatment strategies that the mutated PIK3CA and amplified ERBB2 should be concomitantly inhibited when exposing to continuous anti‐HER2 therapy, while the combination of anti‐HER2 and anti‐PI3Kα treatment was not essential for anti‐HER2 treatment‐naïve patients. These findings improve the understanding of genomics‐guided treatment in the different progressions of HER2+ breast cancer.

Objective Response to First-Line Treatment as a Predictor of Overall Survival in Metastatic Breast Cancer: A Retrospective Analysis from Two Centers over a 25-Year Period

Introduction: The purpose of this study was to study the efficacy of subsequent treatment lines for metastatic breast cancer (MBC), as well as the association between radiologic objective response rate (ORR) and overall survival (OS). Methods: In this retrospective study, consecutive patients treated for MBC in two centers in Greece from January 1, 1992, to December 31, 2016, were identified and clinicopathologic data regarding tumor characteristics and administered treatments were collected. The efficacy per treatment line in terms of ORR, progression-free survival (PFS) and OS, as well as the prognostic value of ORR at first line were investigated. Results: A total of 977 patients with MBC were identified; 950 received any treatment. At first line, ORR was 43.5%, PFS 11.4 months (95% CI 10.4–12.4), and median OS 52.4 months (95% CI 47.7–57.1). Lower ORR and shorter PFS were observed with each subsequent line. Median OS was significantly longer for patients that had an objective response at first line, 61.9 months (95% CI 51.1–69.7) for responders versus 41.3 months (95% CI 44.1–63.3) for nonresponders (p < 0.001). In multivariable analysis, failure to achieve an objective response was an independent predictor of poor survival (hazard ratio 1.70, 95% CI 1.34–2.15, p < 0.001). Conclusion: Late treatment lines for MBC seem to have limited efficacy, while response to first-line therapy is associated with long-term survival. The latter should be considered in the treatment strategy of patients with MBC.

Prognostic Value of BIM Deletion in EGFR-Mutant NSCLC Patients Treated with EGFR-TKIs: A Meta-Analysis.

Background Resistance to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) is inevitable in EGFR-mutant non-small-cell lung cancer (NSCLC) patients. A germline 2903 bp deletion polymorphism of Bcl-2-like protein 11 (BIM) causes reduced expression of proapoptotic BH3-only BIM protein and blocks TKI-induced apoptosis of tumor cells. Yet the association between the deletion polymorphism and response to EGFR-TKI treatment remains inconsistent among clinical observations. Thus, we performed the present meta-analysis. Methods Eligible studies were identified by searching PubMed, Embase, and ClinicalTrials.gov databases prior to March 31, 2021. Hazard ratios (HRs) and 95% confidence intervals (CIs) of progression-free survival (PFS) and overall survival (OS) and odds ratios (ORs) and 95% CIs of objective response rate (ORR) and disease control rate (DCR) were calculated by using a random effects model. Sensitivity, metaregression, and publication bias analyses were also performed. Results A total of 20 datasets (3003 EGFR-mutant NSCLC patients receiving EGFR-TKIs from 18 studies) were included. There were 475 (15.8%) patients having the 2903-bp intron deletion of BIM and 2528 (84.2%) wild-type patients. BIM deletion predicted significantly shorter PFS (HR = 1.35, 95% CI: 1.10-1.64, P = 0.003) and a tendency toward an unfavorable OS (HR = 1.22, 95% CI: 0.99-1.50, P = 0.068). Patients with deletion polymorphism had lower ORR (OR = 0.60, 95% CI: 0.42-0.85, P = 0.004) and DCR (OR = 0.59, 95% CI: 0.38-0.90, P = 0.014) compared with those without deletion. Conclusion BIM deletion polymorphism may confer resistance to EGFR-TKIs and can be used as a biomarker to predict treatment response to EGFR-TKIs in EGFR-mutant NSCLC patients from Asian populations.

Impact of weight loss on treatment with PD-1/PD-L1 inhibitors plus chemotherapy in advanced non-small-cell lung cancer.

Programmed cell death-1 (PD-1)/programmed death-ligand 1 (PD-L1) inhibitors plus chemotherapy have become the standard first line of treatment in patients with advanced non-small-cell lung cancer (NSCLC). However, few studies have explicitly focused on the impact of weight loss on the efficacy of PD-1/PD-L1 inhibitors plus chemotherapy. Thus, we evaluated the clinical implications of weight loss on the survival outcomes in patients who received this treatment. We conducted a retrospective review of medical records of patients with advanced NSCLC who were treated with PD-1/PD-L1 inhibitors plus chemotherapy from December 2018 to December 2020. Significant weight loss was defined as an unintentional weight loss of 5% or more over 6months. We evaluated the progression-free survival (PFS) and overall survival (OS) of patients with or without weight loss. Among the 80 included patients, 37 (46%) had weight loss, and were associated with a lower objective response rate (30 vs 51%, P < 0.05), poorer PFS (2.3 vs 12.0months, P < 0.05), and poorer OS (10.8 vs 23.9months, P < 0.05) than those without weight loss. The Cox proportional-hazard ratios (95% confidence interval) of weight loss were 1.77 (1.01-3.10) for PFS and 2.90 (1.40-6.00) for OS, with adjustments for Eastern Cooperative Oncology Group performance status, PD-L1 tumour proportion score, histology, and central nervous system metastases. Pre-treatment weight loss may reduce treatment efficacy and shorten survival time in patients receiving PD-1/PD-L1 inhibitors plus chemotherapy. Early evaluation and intervention for weight loss might improve oncological outcomes in patients with advanced NSCLC.

715P Nivolumab in pretreated metastatic penile squamous cell carcinoma: Results of the penile cohort from the French AcSé prospective program

Cisplatin-based chemotherapy has shown benefits in the first line setting in patients (pts) with advanced or metastatic penile squamous cell carcinoma (PSCC). However, there is no standard second line treatment. AcSé Nivolumab (N) is a French exploratory program assessing the value of anti-PD1 immunotherapy in pts with rare cancers (NCT03012581). AcSé N is a single arm basket phase II multicentric study aiming to investigate efficacy and safety of N monotherapy. Pts with relapsing/refractory PSCC were eligible after at least 1 line of chemotherapy in radical or palliative settings in a dedicated cohort. Primary endpoint was objective response rate (ORR) at 12 weeks according to RECIST v1.1. Pts received N 240mg IV q2w for a max of 2 years, until disease progression (PD) or intolerable toxicity. Secondary endpoints included progression free survival (PFS), overall survival (OS), best ORR, and safety. 43 PSCC pts were enrolled. Median age was 63, ECOG PS 0/1 in 24%/76% of pts. N was used in 2nd line (35% of pts), 3rd line (44%), and 4th line or beyond (19%). The median number of previous lines of chemotherapy was 2. Metastastic sites were lymph nodes (47%), lung (24%), liver (8%), and bone (6%). The median number of cycles was 5. With a median follow up of 7.9 months (mo), 40 pts (93%) had discontinued N. The 12-week ORR was 14% (4 partial response [PR]), 32% of pts had stable disease (SD), and 54% PD. In intention-to-treat population, the best ORR was 14% (2 CR + 4 PR) with SD in 16% of pts. At the time of analysis, 39 pts (90%) had PD, the 6-month PFS rate was 27.9% (95% CI [17.3; 45.1]), and median PFS 2.9 mo (95% CI [2.3; 5.3]). Moreover, 28 pts (65%) had died (all in PD), the 12-month OS rate was 34.5% (95% CI [22.1; 53.7]), and median OS 8.5 mo (95% CI [4.5; 18.4]). Overall, 3 pts (7%) had at least one grade ≥3 AE. We report the largest prospective study of anti-PD1 immunotherapy in advanced PSCC. Despite a low ORR of 14%, the median OS of 8.5 mo is higher than reported in most studies. These results are encouraging for pts without alternative validated treatments. The value of HPV status as predictive factor will be investigated.

Regorafenib plus toripalimab in patients with metastatic colorectal cancer: a phase Ib/II clinical trial and gut microbiome analysis

SummaryThis is a phase Ib/II study of regorafenib plus toripalimab for colorectal cancer. The objective response rate (ORR) is 15.2% and the disease control rate is 36.4% in evaluable patients with recommended phase II dose (80 mg regorafenib plus toripalimab). The median progression-free survival (PFS) and the median overall survival are 2.1 months and 15.5 months, respectively. Patients with liver metastases have lower ORR than those without (8.7% versus 30.0%). All patients (3/3) with lung-only metastasis respond, whereas no patients (0/4) with liver-only metastasis respond. 94.9% and 38.5% of patients have grade 1 and grade 3 treatment-related adverse events, respectively. Gut microbiome analysis of the baseline fecal samples shows significantly increased relative abundance and positive detection rate of Fusobacterium in non-responders than responders. Patients with high-abundance Fusobacterium have shorter PFS than those with low abundance (median PFS = 2.0 versus 5.2 months; p = 0.002).

Injectable Supramolecular Hydrogel for Locoregional Immune Checkpoint Blockade and Enhanced Cancer Chemo-Immunotherapy.

Immunotherapy has revolutionized the therapeutic modalities of cancer treatment but is severely limited by a low objective response rate and the risk of immune-related side effects. Herein, an injectable supramolecular hydrogel is developed for local delivery of the DPPA-1 peptide (a d-peptide antagonist with a high binding affinity to programmed cell death-ligand 1 (PD-L1)) and doxorubicin (DOX). On the one hand, DOX could kill tumor cells directly and also induce immunogenic cell death to provoke the antitumor immune response. On the other hand, the DPPA-1 peptide could locoregionally block the PD-1/PD-L1 pathway to potentiate T-cell-mediated immune responses and minimize side effects. Eventually, by local injection of this supramolecular hydrogel, the synergistic cancer therapeutic effect was evaluated, showing promise in improving the objective response rate of immunotherapy and minimizing its systemic side effects.

DNA Damage Repair Status Predicts Opposite Clinical Prognosis Immunotherapy and Non-Immunotherapy in Hepatocellular Carcinoma.

Immune checkpoint inhibitors(ICIs) that activate tumor-specific immune responses bring new hope for the treatment of hepatocellular carcinoma(HCC). However, there are still some problems, such as uncertain curative effects and low objective response rates, which limit the curative effect of immunotherapy. Therefore, it is an urgent problem to guide the use of ICIs in HCC based on molecular typing. We downloaded the The Cancer Genome Atlas-Liver hepatocellular carcinoma(TCGA-LIHC) and Mongolian-LIHC cohort. Unsupervised clustering was applied to the highly variable data regarding expression of DNA damage repair(DDR). The CIBERSORT was used to evaluate the proportions of immune cells. The connectivity map(CMap) and pRRophetic algorithms were used to predict the drug sensitivity. There were significant differences in DDR molecular subclasses in HCC(DDR1 and DDR2), and DDR1 patients had low expression of DDR-related genes, while DDR2 patients had high expression of DDR-related genes. Of the patients who received traditional treatment, DDR2 patients had significantly worse overall survival(OS) than DDR1 patients. In contrast, of the patients who received ICIs, DDR2 patients had significantly prolonged OS compared with DDR1 patients. Of the patients who received traditional treatment, patients with high DDR scores had worse OS than those with low DDR scores. However, the survival of patients with high DDR scores after receiving ICIs was significantly higher than that of patients with low DDR scores. The DDR scores of patients in the DDR2 group were significantly higher than those of patients in the DDR1 group. The tumor microenvironment(TME) of DDR2 patients was highly infiltrated by activated immune cells, immune checkpoint molecules and proinflammatory molecules and antigen presentation-related molecules. In this study, HCC patients were divided into the DDR1 and DDR2 group. Moreover, DDR status may serve as a potential biomarker to predict opposite clinical prognosis immunotherapy and non-immunotherapy in HCC.

Abstract 1560: Targeting RNA-binding protein HuR to improve anti-PD-1 immunotherapy response in breast cancer

Abstract Breast cancer has been considered as a less immune-sensitive disease. Patients with metastatic breast cancer have a particularly low objective response rate (ORR) to anti-PD-1/PD-L1 therapy (3%~24%). It will be valuable to improve the treatment efficacy of anti-PD-1 immunotherapy in breast cancer. Recent studies reported that exosomal PD-L1 derived from tumor cells mediated immune surveillance evasion by interacting with the PD-1 receptor on T cells and contributed to the low ORR in anti-PD-1/PD-L1 immunotherapy.The RNA-binding protein Hu antigen R (HuR) is a member of the embryonic lethal abnormal vision (ELAV) family that is overexpressed in a variety of cancers and promotes tumorigenesis by interacting with a subset of oncogenic mRNAs, including PD-L1 mRNA. HuR also plays an important role in the exosome secretion process by regulating RAB27B mRNA. In this study, we aim to identify HuR biological functions in the cancer-immune system and evaluate the combination strategy using a HuR inhibitor with an anti-PD-1 antibody in breast cancer. We show here the direct binding of HuR protein to PD-L1 mRNA in human breast cancer cell line MDA-MB-231 by Ribonucleoprotein immunoprecipitation (RNP-IP). We also show that PD-L1 protein expression level is decreased in HuR knockout clones and in exosomes derived from HuR knockout clones. HuR knockout downregulates exosome secretion with decreased size in MDA-MB-231 cells. KH-3 is a small molecule identified from several chemical libraries that disrupts the binding of HuR and its target mRNAs.To test the combination strategy using a HuR inhibitor and anti-PD-1 antibody in vivo, we established the EMT6 orthotopic mouse breast cancer model. A combination treatment with HuR inhibitor KH-3 and anti-PD-1 antibody inhibits tumor growth and prolongs survival in this breast cancer model. In conclusion, we preliminarily explored the role of HuR in the cancer-immune system, we showed that HuR may be a promising therapeutic target to overcome immune evasion and improve immunotherapy response in breast cancer. Citation Format: Qi Zhang, Xiaoqing Wu, Lan Lan, Lanjing Wei, Liang Xu. Targeting RNA-binding protein HuR to improve anti-PD-1 immunotherapy response in breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1560.

P-167 Efficacy of PD-1 inhibitors for colorectal cancer and polyps in Lynch syndrome patients

Programmed death-1 (PD-1) blockade is effective for colorectal cancer (CRC) with deficient mismatch repair (dMMR) or high microsatellite instability (MSI-H). We aimed to explore its effects on CRCs and colonic polyps in Lynch syndrome (LS) patients. LS patients with CRC who had evaluable tumors and received ≥2 cycles of PD-1 inhibitors were included. PD-1 inhibitors were given as a monotherapy or in combination with other therapies including radiotherapy, chemotherapy, and targeted therapy. Polyps that remained after the treatment were sequenced. Correlations of treatment responses with clinicopathological characteristics and genomic profiles were analyzed. A total of 33 LS patients were included, with a median age of 37 years. The median duration of follow-up was 11.6 months (range, 1.4 to 36.3). The objective response rate (ORR) was 60.6% (n=20), including 21.2% (n=7) complete responses (CRs) and 39.4% (n=13) partial responses (PRs). Three cases of LS CRCs displaying pMMR/MSS or discordant MMR/MSI status were not responsive despite with a moderate/high tumor mutation burden (TMB). Patients carrying deletion/splice-site variants in germline MMR genes had a higher response rate than those with other mutations (100% vs 50.0%, P=0.027). Mucinous differentiation and TMB < 25/Mb were associated with a lower ORR. Four patients had pathologically confirmed remaining adenomas ranging from 8mm to 15mm after the treatment, which were found to be MSS and had a low TMB. PD-1 inhibitors are highly effective for dMMR/MSI-H LS CRCs, but not for pMMR/MSS LS CRCs or those displaying discordant MMR/MSI status. LS polyps that exhibit pMMR/MSS are insensitive to anti-PD-1 treatment.

Clinicopathologic Features and Response to Therapy of NRG1 Fusion-Driven Lung Cancers: The eNRGy1 Global Multicenter Registry.

Although NRG1 fusions are oncogenic drivers across multiple tumor types including lung cancers, these are difficult to study because of their rarity. The global eNRGy1 registry was thus established to characterize NRG1 fusion-positive lung cancers in the largest and most diverse series to date. From June 2018 to February 2020, a consortium of 22 centers from nine countries in Europe, Asia, and the United States contributed data from patients with pathologically confirmed NRG1 fusion-positive lung cancers. Profiling included DNA-based and/or RNA-based next-generation sequencing and fluorescence in situ hybridization. Anonymized clinical, pathologic, molecular, and response (RECIST v1.1) data were centrally curated and analyzed. Although the typified never smoking (57%), mucinous adenocarcinoma (57%), and nonmetastatic (71%) phenotype predominated in 110 patients with NRG1 fusion-positive lung cancer, further diversity, including in smoking history (43%) and histology (43% nonmucinous and 6% nonadenocarcinoma), was elucidated. RNA-based testing identified most fusions (74%). Molecularly, six (of 18) novel 5' partners, 20 unique epidermal growth factor domain-inclusive chimeric events, and heterogeneous 5'/3' breakpoints were found. Platinum-doublet and taxane-based (post-platinum-doublet) chemotherapy achieved low objective response rates (ORRs 13% and 14%, respectively) and modest progression-free survival medians (PFS 5.8 and 4.0 months, respectively). Consistent with a low programmed death ligand-1 expressing (28%) and low tumor mutational burden (median: 0.9 mutations/megabase) immunophenotype, the activity of chemoimmunotherapy and single-agent immunotherapy was poor (ORR 0%/PFS 3.3 months and ORR 20%/PFS 3.6 months, respectively). Afatinib achieved an ORR of 25%, not contingent on fusion type, and a 2.8-month median PFS. NRG1 fusion-positive lung cancers were molecularly, pathologically, and clinically more heterogeneous than previously recognized. The activity of cytotoxic, immune, and targeted therapies was disappointing. Further research examining NRG1-rearranged tumor biology is needed to develop new therapeutic strategies.

Assessment of sacituzumab govitecan (SG) versus treatment of physician’s choice (TPC) cohort by agent in the phase 3 ASCENT study of patients (pts) with metastatic triple-negative breast cancer (mTNBC).

1077 Background: In pts with pretreated mTNBC, standard-of-care chemotherapy is associated with low objective response rates (ORRs) and short median progression-free survival (PFS). SG is an antibody-drug conjugate composed of an anti–Trop-2 antibody coupled to the cytotoxic SN-38 payload via a proprietary, hydrolyzable linker. SG received accelerated FDA approval for treatment of pts with mTNBC who have received ≥2 prior therapies for metastatic disease. The confirmatory phase 3 ASCENT study (NCT02574455) in pts with relapsed/refractory mTNBC demonstrated a significant survival benefit of SG over TPC (median PFS: 5.6 vs 1.7 mo, HR 0.41, P&lt; 0.0001; median overall survival [OS]: 12.1 vs 6.7 mo, HR 0.48, P&lt; 0.0001) with a tolerable safety profile. Here we summarize efficacy results for SG vs each TPC agent in ASCENT to examine how each TPC agent performed individually. Methods: Pts had mTNBC refractory to or progressing after ≥2 prior standard chemotherapy regimens. Pts were randomized 1:1 to receive SG (10 mg/kg intravenously on days 1 and 8, every 21 days) or single-agent TPC (eribulin, vinorelbine, capecitabine, or gemcitabine). Primary endpoint was PFS per RECIST 1.1 by independent review in brain metastases-negative (BMNeg) pts. Secondary endpoints were ORR per RECIST 1.1, duration of response, OS, and safety. Outcomes for each of the agents in the TPC arm were analyzed and compared with SG. Results: Of 529 pts enrolled, 468 were BMNeg. Among pts in the TPC cohort (n = 233), eribulin was the most commonly chosen chemotherapy (n = 126), followed by vinorelbine (n = 47), capecitabine (n = 31), and gemcitabine (n = 29). Treatment with eribulin, vinorelbine, capecitabine, and gemcitabine resulted in shorter median PFS vs SG (2.1, 1.6, 1.6, and 2.7 vs 5.6 mo, respectively); similar results were observed for median OS (6.9, 5.9, 5.2, and 8.4 vs 12.1 mo), ORR (5%, 4%, 6%, and 3% vs 35%), and clinical benefit rate (CBR; 8%, 6%, 10%, and 14% vs 45%). Key grade ≥3 treatment-related adverse events (TRAEs) with TPC overall vs SG included neutropenia (33% vs 51%), leukopenia (5% vs 10%), fatigue (5% vs 3%), and anemia (5% vs 8%). Key grade ≥3 TRAEs with eribulin vs SG included neutropenia (30% vs 51%), leukopenia (5% vs 10%), fatigue (5% vs 3%), anemia (2% vs 8%), and peripheral neuropathy (2% vs none), respectively. The safety profiles of vinorelbine, capecitabine, and gemcitabine combined were consistent with that of TPC overall and with eribulin. One treatment-related death was reported for the TPC arm (eribulin) and none with SG. Conclusions: The efficacy benefit observed with SG vs TPC in pts with mTNBC was retained when evaluating each TPC chemotherapy agent individually. These results confirm that SG should be considered as a new standard of care in pts with pretreated mTNBC. Clinical trial information: NCT02574455 .

Phase II study of binimetinib with imatinib in patients with unresectable KIT-mutant melanoma.

TPS9594 Background: Immune checkpoint inhibitors (ICI) have transformed treatment for patients (pts) with advanced melanoma, as have BRAF/MEK inhibitors for pts with BRAF V600-mutant melanoma. However, pts with acral or mucosal melanomas are in particular need of more options given a lower objective response rate (ORR) to ICI, and lower incidence of BRAF V600 driver mutation. Such BRAF mutations are found in only 5-10% of acral/mucosal melanomas, while KIT mutations/amplifications are found in 10-20%. Even when present, a KIT alteration does not guarantee response to KIT inhibition, with only about one-third responding as previously shown in 3 phase II studies. A significant number of KIT-mutant melanomas have been shown to demonstrate NF1 or SPRED1 loss, with recent preclinical work showing that such alterations are associated with the loss of negative suppression of RAS, resulting in RAS activation and MEK dependence. We hypothesize that NF1 or SPRED1 loss cooperates with KIT mutations to drive melanomagenesis and resistance to KIT inhibition, and propose to target this vulnerability with a combination approach to targeted therapy. This phase II study will be the first to evaluate the efficacy and safety of binimetinib plus imatinib in pts with KIT-mutant melanoma. Methods: This is an investigator-initiated phase II study of binimetinib in combination with imatinib in pts with BRAF V600 WT, KIT-mutant unresectable melanoma who have progressed on or who are ineligible for ICI (NCT04598009). Pts will be ≥18 yo with performance status ECOG 0-2, and have unresectable Stage IIIB/C/D or Stage IV melanoma that is BRAF V600 WT and KIT-mutant by CLIA-certified testing platform. Pts will have progressed on prior ICI or other standard-of-care (SOC) therapies, or be ineligible for or unable to tolerate SOC therapies. Pts with brain metastasis will be eligible if clinically stable and determination made that no CNS-specific treatment is required prior to study start. Pts previously treated with a MEK inhibitor will be excluded. A Simon 2-stage Minimax design will be used; the null hypothesis that the true response rate is 0.1 will be tested against a one-sided alternative. 15 pts will be accrued in the first stage. If there are £1 responses, the study will be stopped. Otherwise, 10 additional pts will be accrued for a total of 25. The null hypothesis that the true response rate is 0.1 will be rejected if ≥6 responses are observed. This yields a type I error rate of 0.05 and power of 0.8017 when the true response rate is 0.3.Primary endpoint: ORR (RECIST). Secondary endpoints: duration of response, progression-free survival, overall survival, clinical benefit rate (CR, PR, or SD ≥16 weeks), safety profile (CTCAE). Exploratory objectives to include investigations of association between clinical response and baseline NF1 and SPRED1 status, and of pathologic correlates of acquired resistance. Study began enrolling pts in December 2020 and is ongoing. Clinical trial information: NCT04598009.

A Low Tumor Mutational Burden and PTEN Mutations Are Predictors of a Negative Response to PD-1 Blockade in MSI-H/dMMR Gastrointestinal Tumors.

This study performed a comprehensive molecular characterization of microsatellite instability-high (MSI-H)/mismatch repair-deficient (dMMR) gastrointestinal (GI) tumors to elucidate predictors of response to PD-1 blockade. Forty-five patients with MSI-H/dMMR GI tumors, including gastric cancer, colorectal cancer, cholangiocarcinoma, small intestine cancer, pancreatic cancer, and duodenal cancer, receiving PD-1 blockade were analyzed. We conducted the genomic profiling of GI tumors by whole-exome sequencing or targeted next-generation sequencing. The tumor microenvironment was evaluated by transcriptomic analysis and multiplex fluorescence IHC. Patients with low tumor mutational burdens (TMBs) had lower objective response rates (ORRs; 0% vs. 48.8%) and a significantly shorter progression-free survival (PFS; 2.3 vs. 15.6 months; HR, 6.20; P = 0.002) than those with high TMBs. Among common gene alterations in GI tumors, only PTEN mutations, which were mutually exclusive with a low TMB, were significantly associated with a lower ORRs than wild-type PTEN (21.4 vs. 54.8%; odds, 4.45; P = 0.045). Compared with wild-type PTEN, PTEN mutations in the phosphatase domain were associated with significantly lower ORRs (12.5 vs. 54.8%; P = 0.049), shorter PFS (2.6 vs. 15.6 months; HR, 5.04; P < 0.001), lower intratumoral CD8+ T-cell levels, higher intratumoral CD204+ macrophage levels, and PI3K/AKT/mTOR pathway enrichment, whereas PTEN mutations in the C2 domain were not. Low TMBs and PTEN mutations, especially mutations in the phosphatase domain associated with an immunosuppressive environment, were mutually exclusive and might be negative predictors of PD-1 blockade responses in patients with MSI-H/dMMR GI tumors.

Immune checkpoint inhibitors (ICI) in advanced upper tract and lower tract urothelial carcinoma (UC): A comparison of outcomes.

406 Background: Despite anatomical and biological differences, upper and lower tract UC (UTUC; LTUC) are usually managed similarly. Modern era clinical trial data comparing their outcomes with ICI are conflicting. We hypothesized that response and outcomes would be similar in patients (pts) with advanced UTUC and LTUC. Methods: We performed a retrospective cohort study collecting demographic, clinicopathologic, treatment, and outcome data for pts with advanced UC receiving ICI (2013-2020) across 24 centers (US; Europe). We compared objective response rate (ORR), overall survival (OS), and progression-free survival (PFS) between pts with UTUC and LTUC. Uni- / multi- variable logistic and Cox regression were used to assess the effect of UTUC on ORR, OS, and PFS. Stratified subgroup analyses were performed according to histology (pure, mixed) and line of treatment (first-line, subsequent). Results: A total of 984 pts were identified, and 707, 717, and 738 were included in ORR, OS, and PFS analyses, respectively. After exclusions, the UTUC group comprised of 130 pts (vs. 616 in LTUC) with median age 71 (40-92) (vs. 70 [32-93]), 62% men (vs. 76%), 41% never smokers (vs. 29%), 62% with history of prior radical surgery for primary tumor (vs. 52%), and 29% with liver metastases (vs. 18%). Table shows results of ORR, OS, and PFS analyses. In the overall population, pts with UTUC and LTUC receiving ICI had comparable ORR, OS, and PFS. Pts with mixed-histology UTUC had significantly lower ORR (adjusted OR 0.20, 95%CI 0.05-0.91) and shorter PFS (adjusted HR 1.66, 95%CI: 1.06-2.59) vs. mixed-histology LTUC. Conclusions: Pts with advanced UTUC and LTUC receiving ICI have similar response and outcomes, except for pts with mixed-histology UTUC vs LTUC. Subset analysis of primary tumor location in ongoing clinical trials can validate our data, while biomarker work is ongoing. [Table: see text]