PD-L1 IHC Research Articles

Characterization of MCL-1 in patients with colorectal cancer (CRC): Expression, molecular profiles, and outcomes.

3085 Background: Myeloid cell leukemia 1 (MCL-1) is a member of the BCL-2 protein family and is anti-apoptotic/pro-survival in function. Dysregulation of MCL-1 expression has been reported in several solid tumors, including lung and breast cancer. In CRC, MCL-1 has been associated with resistance to chemotherapeutic drugs and multi-kinase inhibitor regorafenib. Our study aimed to characterize the molecular features associated with MCL-1 gene expression in CRC. Methods: 28,576 CRC samples were analyzed by Caris Life Sciences (Phoenix, AZ) with WTS (Illumina NovaSeq) and NextGen DNA sequencing (NextSeq, 592 Genes and NovaSEQ, WES). MCL-1 expression was stratified by quartiles where top quartile transcripts per million (TPM) were considered high (Q4) and bottom quartile low (Q1). Cell infiltration (CI) in the tumor microenvironment (TME) was estimated by RNA deconvolution analysis using QuantiSEQ. Interferon-gamma and T-cell inflamed signatures were also calculated from RNA data. X2 and Fisher-Exact tests were used, and statistical significance was determined as a P-value adjusted for multiple comparisons ( q < 0.05). Real world survival was obtained from insurance claims data and Kaplan-Meier estimates were calculated for molecularly defined patients. Results: MCL-1 expression was significantly increased in rectal tumors compared to other primary tumor sites (median TPM [mTPM] 20.8 vs 18.9 vs 18.7, in rectal vs left-sided vs right-sided, respectively, q < 0.0001). MCL-1 high tumors were associated with increased rate of PD-L1 IHC levels (Q1 vs Q4: 4.2% vs 9.7% [all CRC]; 3.7% vs 8.9% [pMMR/MSS], q < 0.0001), while MCL-1-low showed marginally increased rates of TMB-high (8.0% vs 7.0% [all CRC]; 3.3% vs 2.6% [pMMR/MSS], P < 0.05). MCL-1-high expression was associated with a higher T-cell inflamed signature and IFN score ( q < 0.0001). MCL-1 high was associated with higher mutation rates of CDKN2A, BRCA2, KRAS and GNAS, while lower mutation rates of TP53, PIK3CA, PTEN, BRAF, APC, FBXW7, AMER1, SOX9, and SMAD2 and copy number amplifications in several genes ( q < 0.05). MCL-1 high TME had higher CI of M1 and M2 macrophages, monocytes, B cells, NK cells, and T-reg infiltration, while dendritic cells and CD4+ T-cell were lower ( q < 0.05). Patients with high MCL-1 expressing CRC had longer survival (Q4 vs Q1: 33.5 vs 24.8 months, HR 0.72, 95% CI 0.67-0.77, P < 0.0001) and longer time-on-treatment with regorafenib although with limited clinical benefit (Q4 vs Q1: 2.03 vs 1.06 months, HR: 0.67, 95% CI: 0.50-0.89, P = 0.005). Conclusions: Our data show a strong correlation between distinct immune biomarkers, TME cell infiltration and MCL-1 expression in CRC. Furthermore, increased tumor MCL-1 expression improved patient prognosis and treatment outcomes. These findings suggest a key clinical role for MCL-1 as an important modulator of anti-tumor immunity and TME and a potential biomarker in CRC.

Postoperative prognosis in patients with NSCLC with different EGFR mutation sites.

e20528 Background: Lung cancer can be divided into small cell lung cancer and non-small cell lung cancer. At the same time, non-small cell lung cancer can be divided into non-small cell lung cancer with different molecular mutations. Among them, the EGFR mutation accounts for about 50% of the patients with non-small cell lung cancer in China, which is a large group of patients. The EGFR mutation has many sites and many forms of mutational subtypes, including common mutations such as L858R, and rare mutations. Although the proportion of rare mutations is small, it is still different from common mutations in patients with TKI treatment and immunity. Methods: This study collected and analyzed the data from Formalin-Fixed Paraffin-Embedded (FFPE) tissues of 330 NSCLC patients which received surgery and underwent a targeted next-generation sequencing (NGS) assay performed by 3DMed Clinical Laboratory Inc., a College of American Pathologists (CAP) certified and Clinical Laboratory Improvement Amendments (CLIA) certified laboratory of 3D Medicines Inc. between January, 2019 and June, 2022 in China, to obtain a comprehensive molecular profile of EGFR mutations. genomic alterations, tumor mutational burden (TMB) and PD-L1 expression were analyzed. Gene mutation and TMB level were analyzed by NGS, detected PD-L1 expression by using Dako PD-L1 IHC 22C3 pharmDx, Tumor Proportion Score (TPS) was used to determine expression of PD-L1. Finally, the postoperative follow-up data were also collected and analyzed in this study. Results: Therefore, we retrospectively analyzed the tissue samples of patients with non-small cell lung cancer who received surgical treatment, and carried out NGS detection and analysis, as well as postoperative follow-up. Among them, patients with EGFR mutations accounted for 51.2%. We further analyzed the TMB and PD-L1 expression levels of different EGFR mutation subtypes. First, we found that different EGFR mutation sites, whether common mutations such as L859R, 19del or unusual mutations such as S768I, There is no difference in the prognosis after operation, but it is very significant that our results show that there are two or more EGFR mutations at the same time. Conclusions: NSCLC with EGFR mutation is a very large group of patients, which should be further subdivided into different subtypes according to different EGFR mutation sites, and should perform individualized management. This study found that patients with two or more EGFR mutations and patients with EGFR single site mutations are different types of NSCLC, with different postoperative prognosis, and it may be related to the differences in the expression levels of TMB and PD-L1, which is a direction worthy of further exploration in the future.

Neoadjuvant tislelizumab, a PD-1 mAb plus nab-paclitaxel (nab-P) followed by tislelizumab plus epirubicin/cyclophosphamide (EC) for triple-negative breast cancers (TNBC): Interim analysis of clinical response in a phase 2 TREND trial.

e14623 Background: Chemo-based immunotherapy improves the prognosis of TNBC. However, the dominant population and optimal chemo-backbone of neoadjuvant immunotherapy remain undefined. Aim of TREND trial was to assess the efficacy and safety of tislelizumab in combination with nab-P and EC (nab-P-EC) in neoadjuvant therapy of TNBC. Methods: In this prospective, single-arm phase 2 clinical study, untreated TNBC patients who have clinically node-positive or at least T2 disease without distant metastasis were eligible. Before surgery, enrolled patients received tislelizumab (200 mg IV Q3W) plus weekly nab-P (100 mg/m² IV Q3W) for 12 weeks, followed by tislelizumab (200 mg IV Q3W) plus epirubicin (75 mg/m² IV Q3W) and cyclophosphamide (600 mg/m² IV Q3W) for the subsequently 12 weeks. The primary endpoint was pCR (ypT0/Tis ypN0) and secondary endpoints was objective response rate (ORR, RECIST v1.1). Combined positive score (CPS) of PD-L1 expression in pre-treatment biopsy samples was tested by PD-L1 IHC 22C3 PharmDx. Single-cell RNA sequencing, single-cell TCR sequencing, mass cytometry by time of flight, whole exome sequencing, RNA-seq and olink-assay were performed on pre- and post-treatment samples from primary tumors, metastatic lymph nodes and peripheral blood. Results: Of 43 enrolled patients from Nov 2020 to Nov 2022, 21 patients completed neoadjuvant therapy and accepted surgery in per protocol set (PPS; median age 48 years; range 25-69 years), and 16 were still on treatment. In PPS, the pCR (ypT0/is ypN0) rate was 71.43% (15/21). For different target lesions, 15 patients achieved ypT0/Tis (pCR rate = 71.43%) and 20 reached ypN0 (pCR rate = 95.24%). When stratified by CPS, pCR (ypT0/is ypN0) rate were 68.4%,72.2% and 76.9% in CPS ≥ 1, CPS ≥ 5 and CPS ≥ 10 subgroups, respectively. The ORR in PPS was 90.48% (n = 19/21, 95% CI: 68.18 - 98.33) and DCR reached 95.24% (n = 20/21, 95% CI: 74.13 - 99.75), including 9 complete response and 10 partial response. Treatment emergent adverse event (TEAE) occurred in 74.4% patients (32/43), of which 69.8% were Immune-related adverse event (irAE) (30/43). Grade ≥ 3 IrAE was 7.0% (3/43) and no treatment-related deaths were found. Conclusions: Combining tislelizumab and neoadjuvant nab-P-EC achieved favorable efficacy in TNBC, supporting that platinum-free regimen was non-inferior as a chemo-backbone. For heterogeneity of efficacy to immunotherapy, metastatic tumors in lymph nodes responded better to tislelizumab than primary tumor, suggesting that node-positive patients were potentially dominant population of neoadjuvant immunotherapy. Further results from the ongoing TREND trial and subsequent analysis of mechanism are urgently awaited. Clinical trial information: ChiCTR2000035262 .

Artificial intelligence algorithm developed to predict immune checkpoint inhibitors efficacy in non–small-cell lung cancer.

9132 Background: Many non-small cell lung cancer (NSCLC) patients with high PD-L1 IHC expression and/or high TMB level do not respond to immune-check point inhibitors (ICIs). Discovery of novel predictive biomarkers for ICI response in NSCLC continues to be a critical unmet medical need, given the expense, potential toxicity, and therapeutic delay due to ICI treatment without benefit. Methods: We developed a supervised deep learning algorithm (Deep-IO) to predict therapeutic response to ICIs in NSCLC patients from standard histology whole slide hematoxylin and eosin (H&E) images, which was trained based on ICI objective response rate. We utilized a convolutional neural network (CNN) implemented in Pytorch. The efficiency of the Deep-IO was evaluated through classification performance metrics and the area under the receiver operating characteristic curve (AUROC). The algorithm was trained and tested on 85218 tiles (size: 512x512 pixels) in 446 advanced stage NSCLC patients from the Dana Farber Cancer Institute (DFCI), all treated with ICI monotherapy. Results: The objective response rate, comprising complete and partial response, was 26% (n = 114) in the overall cohort. The DFCI patient cohort was randomly split into a training set (N=379, 85%) and a test set (N=67, 15%). The classifier’s predicted class (responder vs non-responder) probabilities at the tiles level were averaged for each patient. Quantitative evaluation of whole section test dataset shows that the developed model achieves the accuracy of 0.72, weighted average (WAVG) precision of 0.77, WAVG recall of 0.72 and WAVG F-score of 0.74 on classifying ICI non-responders from responders. Comparing with PD-L1 expression (TPS%) and TMB (mu/Mb), Deep-IO had superior predictive power for ICI response (AUROC=0.75) in the test set. The combined Deep-IO+PD-L1 scores resulted in a significantly greater AUROC value of 0.82 compared to single tests and a 32% improvement in specificity (0.88 vs. 0.56) compared to PD-L1 evaluation alone (Table). Conclusions: This proof-of-concept study shows that an artificial intelligence–powered H&E image classifier can predict ICI effectiveness in NSCLC. Deep-IO outperformed both established predictive biomarkers. We will assess Deep-IO in additional external NSCLC data sets for validation and confirmation. [Table: see text]

PD-L1 expression in Chinese patients with solid tumor and its correlation with gene alternations.

e14640 Background: Immune checkpoint blockade are recommended in more and more solid tumors for first-line or posterior treatment, and PD-L1 expression is a crucial predictive biomarker for immunotherapy. However, the expression can be influenced by many factors. Methods: A total of 1743 Chinese patients with solid tumor was retrospectively identified. The Dako PD-L1 IHC 22C3 pharmDx assay was used to detect PD-L1 protein expression. And Tumor Proportion Score (TPS) ≥ 1% was defined as positive expression, TPS ≥ 50% was defined as high expression. Genomic profiling was performed on tumor tissue and matched peripheral blood samples. Only the tumor subtypes with sufficient sample size were used for correlation analysis. Results: PD-L1 positive expression occurred in 45.6% patients and high expression occurred in 8.1% patients. The highest expression incidences occurred in cervical cancer as of 78.8%, followed by lung cancer (53.8%), esophageal cancer (53.7%) and gastric cancer (42.7%). The PD-L1 expression assessed by TPS was consistent with that assessed by Combined Positive Score (CPS) in multiple tumors. However, it was significantly different in gastrointestinal tumors, especially in colorectal cancer (TPS>1%: 30.4% vs. CPS>1: 80.6%). In addition, gene alternations including TP53, CDKN2A, LRP1B, KRAS and PIK3CA apparently occurred in patients with high PD-L1 expression. Moreover, high tumor mutation burden (TMB-H) was associated with PD-L1 positive expression in these Chinese patients. Besides, no correlation was found between microsatellite instability (MSI) and PD-L1 expression. Conclusions: Our results illustrated genomic correlates of PD-L1 expression in Chinese solid tumor patients. These findings may broaden the application of immune checkpoint blockade to patients harboring specific molecular characteristics.

Impact of CLEC3B mRNA expression on genetic landscape and immune tumor-microenvironment in NSCLC.

e20517 Background: Downregulation of C-type lectin domain family 3 member B (CLEC3B) is observed in non-small cell lung cancer (NSCLC), but its role remains largely unclear. Thus, we conducted this large scale genomic and transcriptomic analysis to gain novel insights into molecular and immunological functions of CLEC3B mRNA expression in NSCLC. Methods: Five publicly available WTS/WES NSCLC datasets (TCGA LUAD/LUSC, GSE41271, GSE66863, GSE81089, BATTLE) and the lung cancer single-cell atlas (Salcher, Cancer Cell 2022) were re-analyzed to decipher various molecular and biological aspects of CLEC3B in NSCLC. Findings were validated in a cohort of 19,982 NSCLC samples, which were centrally profiled (Caris Life Sciences, Phoenix, AZ) using WES/WTS. The cohort was stratified in quartiles according to CLEC3B mRNA expression status, with CLEC3Bhigh ( CLEC3BH) and CLEC3Blow ( CLEC3BL) expression defined as top and bottom quartile of transcripts per million (TPM) for further comparison. Immune cell fractions were calculated using QuantiSeq. Real-world overall survival (OS) was calculated using data from insurance claims. Results: CLEC3B mRNA expression was diminished in NSCLC compared to matched normal tissue (p < 0.001). Adenomatous histology was associated with higher CLEC3B expression compared to squamous/large-cell carcinomas (p < 0.005). In CLEC3B H tumors we observed lower rates of somatic mutations in TP53 (44.1 vs 81.7%), TTN (54.1 vs 79%), CDKN2A (5.2 vs 15%), but higher rates in KRAS (24 vs 7.8%) and STK11 (15.8 vs 2.69%) (all, q < 0.01), which we corroborated in our validation cohort (TP53 (52.4 vs 74.7%), CDKN2A (8.3 vs 13%), RB1 (9.2 vs 13.5%), KMT2D (3.8 vs 7.3%), KRAS (31.8 vs 25.6%), EGFR (17.2 vs 8.1%) and STK11 (15.9 vs 11.3%, all q < 0.05)). Further, CLEC3BH tumors were characterized by an immunosuppressive phenotype reflected by lower TMB and lower rates of MSI-H/dMMR, lower PD-L1 IHC expression and abundance of M2 macrophages and regulatory T-cells. Analysis of bulk and single cell transcriptomic datasets revealed that CLEC3BH was linked to endothelium-specific signaling and higher expression levels in endothelial cells. Finally, increased CLEC3B expression was associated with improved OS in the exploratory and validation cohorts. Conclusions: We herein described the molecular landscape of NSCLCs according to CLEC3B mRNA expression. We speculate that CLEC3B is mainly expressed by endothelial cells, and observed that CLEC3BH was associated with a distinct genetic profile and an immunosuppressive tumor-microenvironment. Thus, CLEC3B expression warrants further investigation as a stratification marker for NSCLC patients undergoing immune checkpoint therapy.

Impact of a pathologist-driven molecular testing protocol on veterans with non-small cell lung cancer.

e21209 Background: Precision medicine has shifted the paradigm of cancer treatment in the last two decades. Currently, with over ten targetable mutations in non-small cell lung cancer (NSCLC) and increasingly emerging biomarkers for immunotherapy, genomic testing is necessary for every NSCLC patient. However, this multiple biomarker-defined treatment approach is often compromised by many challenges including slow turnaround time (TAT), high rate of quantity not sufficient (QNS) resulting in inaccurate molecular testing or needs for second biopsy. These barriers lead to increased risk of developing medical complications from re-biopsy or treatment delay as well as additional social and financial support, which is not always available for veterans. A recent study reported that up a one third of veterans with NSCLC containing highly actionable mutations were not prescribed targeted treatment, among which, 25% of patients do not have a documented molecular testing results. Herein, we reported a pathologist-driven protocol to enhance the implement of molecular testing on guiding NSCLC treatment in veteran population. Methods: A pathologist-driven molecular testing protocol is applied West Los Angeles VA hospital since 2018. First, in preparation for diagnosis and molecular testing, tissue block will be cut in serial sections in the following priority: 2 slides for H&E, 4 slides for IHC, 2 slides for PD-L1 staining. An additional slide is made for quality control (QC) purpose before 10 additional slides are cut for molecular testing and 6 for FISH studies. The reminder of the tissue block will be cut in serial sections and preserved in a vial along with tissue shaved at initial block effacement. Every tissue block will be exhausted. Upon initial evaluation of H&E slides, the reviewing pathologist, independent of the treating oncologist, will order molecular testing including EGFR, ALK, ROS and BRAF by NGS if NSCLC is identified. PD-L1 IHC staining is also ordered automatically regardless of the histology. If a clinically actionable mutation is detected, a mutation notification is immediately sent via email by the molecular pathologist to alert the treating oncologist. Results: After implementing this protocol, we observed a decreased rate of QNS (~30% reduction) and subsequently the need for 2ndbiopsy dropped substantially. We also observed a faster TAT between initial cancer diagnosis (within 7 days) and the resulting of molecular testing to guide subsequent treatment. Conclusions: Refined tissue processing and pathologist driven ordering system can significantly impact initial management of patients with NSCLC as it reduces the rate of QNS and repeat biopsy/TAT. This protocol can be easily implemented in VA system or other community based healthcare system.

Abstract LB291: Uncovering gene fusions with 3D genomics: from clinical validation to actionable insights for undiagnosable solid tumors

Abstract Identifying gene fusions in tumor biopsies is critical for understanding disease etiology; however, clinical NGS panels often fail to yield clear genetic drivers. A key challenge is that RNA-seq does not perform well in FFPE tissue blocks due to RNA degradation and/or RNA panel design, and cannot detect breakpoints outside of the gene body, which are established clinical biomarkers with mechanistic significance and clinical utility in solid hematological cancers. We developed a novel DNA-based partner-agnostic approach for identifying fusions from FFPE tumors using 3D genomics based on Arima-HiC technology and NGS. We profiled 184 FFPE tumors across various tumor types. This cohort includes 33 tumors with known gene fusions detected by RNA panels for clinical concordance analysis. It also includes 151 FFPE tumors, including 62 CNS tumors, 59 gynecological sarcomas, and 22 solid heme tumors, with no detectable genetic drivers from prior DNA and RNA panel CLIA assays. For clinical concordance, Arima-HiC technology detected 33/33 fusions previously detected by RNA panels. For clinical validation and utility studies in our driver-negative cohort, Arima-HiC detected 1 or more fusions in 72% (109/151) of tumors. To attribute clinical significance, we compared the genes implicated in our fusion calls with NCCN and WHO guidelines, and OncoKB, and assigned which tumors had an FDA-approved therapeutic level biomarker (“Tier 1”), a biomarker targeted in an ongoing clinical trial (“Tier 2”), or a diagnostic/prognostic biomarker (“Tier 3”). Arima-HiC analysis found 33.8% (51/151) of tumors had Tier 1 biomarkers, 4.0% (6/151) had Tier 2 biomarkers, and a further 14.6% (22/151) had Tier 3 biomarkers, indicating an overall yield of clinically actionable biomarkers at 52.3%. Several cases with Tier 1-3 fusions underwent confirmatory immunohistochemistry testing for oncoprotein expression, and 91.6% (11/12) showed diffuse or focally positive staining. To highlight examples from prospectively analyzed cases from this cohort, we identified a novel PD-L1 rearrangement in a pediatric glioma tumor that was not detected by DNA or RNA panels, which we confirmed by PD-L1 IHC, and the patient was administered pembrolizumab after tumor recurrence and has since exhibited stable disease. We also identified a MYBL1 fusion in a glioma that spared the patient unnecessary chemotherapy post-resection. Our findings provide evidence of clinical concordance, validation, and utility, and underscore the need for 3D genome profiling to increase diagnostic yield by finding clinically actionable fusions in FFPE solid tumors. Citation Format: Anthony Schmitt, Kristin Sikkink, Kristyn Galbraith, Misha Movahed-Ezazi, George Jour, Matija Snuderl. Uncovering gene fusions with 3D genomics: from clinical validation to actionable insights for undiagnosable solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB291.

Abstract CT067: Pembrolizumab with and without sacituzumab govitecan as first-line treatment for metastatic non-small-cell lung cancer (NSCLC) with PD-L1 TPS ≥50%: phase 3 KEYNOTE-D46/EVOKE-03 study

Abstract Background: Sacituzumab govitecan is an antibody-drug conjugate comprising an anti-trophoblast cell-surface antigen 2 (Trop-2) antibody coupled to a potent payload, SN-38, via a proprietary, hydrolysable linker. In heavily pretreated patients with metastatic NSCLC, sacituzumab govitecan showed a durable antitumor response and was well tolerated with a 10-mg/kg dose regimen. Monotherapy with the anti-PD-1 monoclonal antibody pembrolizumab is a standard-of-care therapy for patients with previously untreated advanced/metastatic NSCLC with no sensitizing EGFR or ALK alterations and a PD-L1 tumor proportion score (TPS) ≥50%. KEYNOTE-D46 evaluates whether adding sacituzumab govitecan to pembrolizumab monotherapy can improve outcomes in patients with metastatic NSCLC with PD-L1 TPS ≥50%. Trial Design: In this phase 3, open-label, active comparator-controlled, randomized study, ~614 eligible adults with previously untreated metastatic NSCLC; no EGFR, ALK, or ROS1 alterations; PD-L1 TPS ≥50%; and measurable disease per RECIST version 1.1 will be randomized 1:1 to receive either pembrolizumab 200 mg Q3W for up to 35 cycles plus sacituzumab govitecan 10 mg/kg on days 1 and 8 of each Q3W cycle (no maximum treatment duration) or pembrolizumab 200 mg Q3W for up to 35 cycles. Randomization is stratified by ECOG PS (0 vs 1), histology (squamous vs nonsquamous), and geographic region (East Asia vs North America/Western Europe/Australia vs Rest of World). Treatment continues until PD, death, unacceptable toxicity, or another treatment discontinuation criterion is met, or (for pembrolizumab) completion of 35 cycles. Dual primary endpoints are PFS per RECIST version 1.1 by blinded independent central review (BICR) and OS. Secondary endpoints include ORR and duration of response per RECIST version 1.1 by BICR, safety, and patient-reported outcomes. Radiographic imaging occurs at baseline; weeks 6, 12, 18, and 24 from randomization; every 9 weeks thereafter through week 51; and then once every 12 weeks until BICR-confirmed PD or the start of new anticancer treatment, pregnancy, withdrawal of consent, or death. PD-L1 expression status is assessed at a central laboratory using PD-L1 IHC 22C3 pharmDx (Agilent, Santa Clara, CA). Health-related quality of life is assessed using validated patient-reported outcome instruments including the EORTC Quality of Life Questionnaire-Core 30 and Quality of Life Questionnaire-Lung Cancer 13. AEs are assessed according to National Cancer Institute Common Terminology Criteria for Adverse Events version 5.0. Enrollment started on December 9, 2022 and is currently ongoing. Citation Format: Mor Moskovitz, Isamu Okamoto, Peng Chen, Jilpa Patel, Sabeen Mekan, M. Catherine Pietanza, Yalin Zhu, Renata Eiras, Marcello Tiseo. Pembrolizumab with and without sacituzumab govitecan as first-line treatment for metastatic non-small-cell lung cancer (NSCLC) with PD-L1 TPS ≥50%: phase 3 KEYNOTE-D46/EVOKE-03 study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT067.

Study of PD-L1 Expression in Tumours Based on Site and Histology of Tumour – The Experience of a Tertiary Referral Laboratory

Background: PD-L1 IHC test is used as a predictive biomarker using FDA-approved assays to select patients likely to benefit from immunotherapy in several advanced-stage tumors. We aim to present our data regarding the prevalence and expression pattern of PD-L1 across various tumors based on site and histology and compare them with those of the reported literature. Material and Methods: A retrospective study of 301 cases of various tumors at different sites was done for PD-L1 IHC using the 22С3 pharmDx assay on the recommended platform.Results: Out of 237 non small cell lung carcinoma cases, 14.7% were squamous and 85.2% were of nonsquamous histotype, with adenocarcinomas comprising the majority (82.2%). Fifty-seven percent of non small cell lung carcinoma was PD-L1 positive, 28.6% showed high expression. Sixty percent of the squamous and 56.4% of the non-squamous histotypes showed positive immunoexpression. Amongst non-squamous types, 56.4% of adenocarcinomas and 66.6% of sarcomatoid carcinomas were positive. At metastatic sites, 54.3% of on small cell lung carcinoma were positive. In head and neck squamous cell carcinoma, the majority (10/11) of cases were from the oral cavity; 81.8% of total cases were positive, 27.2% were strong expressors. For other sites, the number of cases showing PD-L1 immunopositivity is as follows: oesophageal squamous cell carcinoma (2/6), gastric adenocarcinoma (2/6), triple negative breast carcinoma (0/3), urothelial carcinoma (2/5), gall bladder (2/5), pancreatico-biliary (2/11), and colorectal (2/17) adenocarcinomas. In these tumors, PD-L1 immunoexpression did not differ significantly by age or gender. Conclusion: Our study showed PD-L1 immunopositivity in 57% of non small cell lung carcinoma and 81.8% of head and neck squamous cell carcinoma, which is comparable to international studies. Further studies with larger sample sizes are needed to see their expression pattern in tumors at other sites and with different histologies.

Abstract 970: Clinical analysis of patients (pts) with lung cancer treated with anti-PD1/PDL1 therapy

Abstract Background: Characterization of Lung cancer treated with anti-PD1/PDL1 therapy was approach to predict the clinical benefit. This research is a prospective and observational study of long-term immunization therapy safety in routine clinical practice in lung cancer. Methods: This study obtained 395 Chinese patients lung cancer patients who underwent surgical resection or biopsies from January 2020 to January 2022. It is aimed to evaluated the value of TMB, MSI, and PD-1 expression in the pts subset that was therapy at anti-PD1/PDL1 therapy(n=47), other anticancer therapies (n=348) included chemoradiation therapy(55%), docetaxel(18%), EGFR-TKIs (16%), pemetrexed (5%) etc. Results: In this cohort, lung cancer pts treated with anti-PD1/PDL1 therapy had a higher proportion of MSI-H than others (7.7% vs 3.4%). PD-L1 High expression in two groups (anti-PD1/PDL1 therapy vs others) about in 19.1%(n=9) vs 10.6% (n=37), and low expression in 8.9% (n =31) vs 10.6% (n=5) pts. Median TMB was 13 mut/Mb from anti-PD1/PDL1 therapy and 9.6 mut/Mb from other therapy. Conclusions: Lung cancer pts were integrated after to immunotherapy vs other therapy, most pts received multiple subsequent anticancer therapies. In this study, immune-related biomarker analysis of lung cancer populations with multiple treatment methods may help improve the efficacy of precise treatment in lung cancer. Table Other therapy(n = 348) Anti-PD1/PDL1 therapy(n = 47) PD-L1 IHC High 10.6% 19.1% PD-L1 IHC Low 8.9% 10.6% TMB Median (mut/Mb) 9.6 13.0 MSS Status 76.0% 74.4% MSI Low Status 20.7% 17.9% MSI High Status 3.4% 7.7% Citation Format: Xin Zhao, Siyao Liu, Junyan Su. Clinical analysis of patients (pts) with lung cancer treated with anti-PD1/PDL1 therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 970.

Abstract 5702: Ovarian cancer tumor microenvironment and atezolizumab (atezo) clinical activity: IMagyn050 sub-study

Abstract Background: Tumor biomarkers such as CD8 density and location (i.e., immune inflamed phenotype) and immune rich molecular subtype have been linked to immune checkpoint blockade (ICB) overall survival (OS) in different cancers. The IMagyn050 trial (NCT03038100), which evaluated the efficacy of Atezo vs placebo (Pla) with carboplatin, paclitaxel and bevacizumab (CPB) in front line ovarian cancer patient (pts), did not meet its co-primary endpoints of PFS in ITT or PD-L1+ (Moore et al. JCO 2021). In the current IMagyn050 substudy we assessed potential predictive tumor immune biomarkers for Atezo clinical benefit. Methods: FFPE tumors from the biomarker evaluable population were tested for PD-L1 IHC, CD8/PanCK IHC (total CD8 T cells and immune location phenotypes [inflamed, excluded, desert]) and RNA-seq (to derive molecular subtypes, biological pathways and cellular components [xCELL]) in tissue from baseline (n=860), on-treatment (OT, 9 weeks, n=233), intra- (n=8) and inter-lesion (n=12) matched samples. Hazard ratio (HR) interaction test from multivariate adjusted Cox-regression analysis for PFS and OS was performed to test predictive biomarkers. Results: While tumors with CD8 T cells, immunoreactive molecular subtypes or immune inflamed phenotype were enriched for PD-L1+, only pts with immune inflamed tumors showed improved OS Atezo benefit (HR 0.67). Improved Atezo PFS/OS benefit was also observed in pts with whose tumors had high oxidative phosphorylation (OXPHOS, HR: 0.72/0.65) and UV Response (UV, HR: 0.64/0.58) but not IFNγ response. Plasma B cells were linked to improved OS Atezo benefit vs Pla (HR 0.53). We leveraged OT samples from pts in the neoadjuvant cohort to assess treatment effect on the tumor microenvironment. Analyses showed that CPB reduced tumor proliferation and increased tumor immune inflammation (CD8 T cells, PD-L1 and IFNα/IFNγ response), further increased by Atezo. Immune inflammation is challenging in ovarian cancer due to extensive tumor heterogeneity. Prevalence of tumor biomarkers varied by anatomic locations: total CD8, CD8 localization and molecular subtypes. Inter- and intra-lesion biomarker status within the same pt showed PD-L1 and plasma B cells as most consistent. Molecular subtypes and immune phenotypes had moderate intra-lesion agreement but discordant between lesions. PD-L1 and OXPHOS were the only biomarkers linked to Atezo benefit regardless of anatomical location. Conclusion: This comprehensive exploratory study suggests that DNA damage, OXPHOS, plasma B cells and immune inflamed tumors, but not molecular subtypes or total CD8 T cells, may predict Atezo + CPB OS. This treatment promotes immune inflammation in OC tumors. Notably, we found that several biomarkers are highly heterogeneous. Our findings highlight the challenges of achieving durable clinical benefit from targeted immunotherapy in ovarian cancer pts. Citation Format: Venkatesh Krishnan, Ching-Wei Chang, Habib Hamidi, Michael A. Bookman, Charles Landen, Tashanna Myers, Hiroaki Kajiyama, Sakari Hietanen, Lyndsay Willmott, Premal Thaker, Cagatay Taskiran, Jalid Sehouli, Victor Khor, Yvonne Lin Liu, Sandro Pignata, Kathleen Moore, Luciana Molinero. Ovarian cancer tumor microenvironment and atezolizumab (atezo) clinical activity: IMagyn050 sub-study. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5702.

Abstract 3383: Liquid biopsy for PDL-1 status by analysis of cfRNA: Clinical data from a large community practice

Abstract PD-L1 testing via immunochemistry has become a widely used tool to predict response to immune checkpoint inhibitor (ICI) therapy in many tumor types. However this marker can be expressed heterogeneously, and can vary with time, treatment effects, and local factors including cytokine expression. Gene expression profiles of immunologically active genes are currently being studied to more accurately predict response to ICI treatment. To evaluate a potentially more straightforward way to accomplish this, we utilized an assay of cfRNA in plasma for PD-L1, utilizing a real-time PCR based assay (Circulogene, Inc, Birmingham, AL). The demonstrated limit of detection for PD-L1 RNA was 1 copy/ul. Results were reported as either not detected, or low at over 1%, or high at over 50%. We used the PCR 30th percentile Ct value corresponding to a tissue IHC PD-L1 of>50%, and the 66th percentile Ct value corresponding to a tissue PD-L1 expression of >1%. We then collected data on over 400 patients over a two year period at a large community oncology practice and at a university clinic (Florida Cancer Specialists and Atrium Health/Wake Forest-Baptist Comprehensive Cancer Center) who had a clinical necessity for molecular testing in a commercially available setting with a CLIA certified lab. In some cases the corresponding tissue PD-L1 testing was also available, and may have been either positive or negative.To date 41 patients have been found to have high levels of cfRNA for PD-L1. Their clinical course has been analyzed using the electronic medical record. Some patients have received standard of care therapy, and some have been given CPI therapy with or without chemotherapy, if the attending oncologist felt this to be the best palliative option. These include tumors such as CRPC, metastatic low grade neuroendocrine carcinoma and HR+ metastatic breast carcinoma, that have rarely been treated successfully with CPI therapy. Tumor types - all are stage IV solid tumor patients: 19 NSCLC, 7 breast carcinoma, 3 colorectal cancer, 3 castrate resistant prostate carcinoma, 9 other tumor types.Data collection for tumor response or clinical benefit on the 41 patients is ongoing and will be presented at the meeting, and compared to published CPI response data using standard tissue IHC testing. Citation Format: Lowell L. Hart, Magali Van den Bergh. Liquid biopsy for PDL-1 status by analysis of cfRNA: Clinical data from a large community practice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3383.

Expression of PD-L1 in triple negative breast cancer

Introduction: The second leading cause of cancer deaths in women is breast cancer. Breast cancer awareness has increased due to mammography screenings. The aim of study is to evaluate the prevalence of PD-L1 expression in TNBC cases and to correlate it with clinicopathological parameters. Method: PDL1 expression is measured by immunohistochemical technique using Dako kits, PD-L1 IHC 22C3 pharm Dx, on 44 paraffin block samples from Duhok municipal labs. If the specimen has a combined positive score (CPS) of 10 or higher, it expresses PD-L1. Age groups, grades, kinds, stages, and PDL1, lymph node involvement are studied. Results: 44 cross-sectional patients, mean and SD (47.7±14) years old. (54.5%) of patients in middle age group, (63.6%) at grade III, majority (88.6%) have IDC type and (75%) have negative PDL1, (63.6%) have KI69 less than 20, (70.5%) at stage T2, and (45.5%) have N1 lymph node involvement. There is significant association between PDL1 and Ki67, (100%) of patients with positive PDL1 have Ki67 more than 20 while (15.2%) of patients with negative PDL1 have Ki67 more than 20. Conclusion: 75% of middle-aged individuals with grade III had negative PDL1. All PDL1-positive patients have Ki67 above 20. Different research employ 1%, 5%, or 10% cutoff values, which affects PDL1.

Genomic and transcriptomic insights into the precision treatment of pulmonary enteric adenocarcinoma

BackgroundPulmonary enteric adenocarcinoma (PEAC) is a rare subtype of lung adenocarcinoma. More investigations about precision therapy in PEAC were required to improve the prognosis. Methods: Twenty-four patients with PEAC were enrolled in this study. Tumor tissue samples were available from 17 patients for both DNA and RNA based next-generation sequencing, PD-L1 IHC staining and PCR-based microsatellite instability (MSI) analysis. Results: TP53 (70.6%) and KRAS (47.1%) were the most frequently mutated genes in PEAC. For KRAS mutations, the prevalence of G12D (37.5%) and G12V (37.5%) was higher than G12A (12.5%) and G12C (12.5%). Actionable mutations in receptor tyrosine kinase (including one EGFR and two ALK mutations), PI3K/mTOR, RAS/RAF/MEK, homologous recombination repair (HRR) and cell cycle signaling pathways were identified in 94.1% of patients with PEAC. While PD-L1 expression was observed in 17.6% (3/17) patients, no MSI-H patients were identified. Transcriptomic data showed that two patients with positive PD-L1 expression had relatively high immune infiltration. In addition, prolonged survival was obtained with the treatment of osimertinib, ensartinib, and immunotherapy combined with chemotherapy in two EGFR-mutated, one ALK-rearranged, and one PD-L1 expressed patients, respectively. Conclusion: PEAC is a disease of genetic heterogeneity. The administration of EGFR and ALK inhibitors was effective in patients with PEAC. PD-L1 expression and KRAS mutation type may be used as predictive biomarkers for immunotherapy in PEAC. This study provided both theoretical basis and clinical evidence for PEAC.

Abstract P3-06-02: TATEN TRIAL (SOLTI-1716) Targeting non-Luminal disease by PAM50 with pembrolizumab + paclitaxel in Hormone Receptor-positive/HER2-negative (HR+/HER2-) metastatic breast cancer (MBC): interim analysis

Abstract Background Within HR+/HER2- disease, patients with non-luminal subtypes of breast cancer (HER2-enriched [HER2-E] and Basal-like) have poorer prognosis than those with luminal subtypes, may be more sensitive to chemotherapy, and have higher expression of immune-related genes and tumor infiltrating lymphocytes (TILs). Here, we report the interim efficacy and safety data of the TATEN trial (NCT04251169), the first study designed to evaluate pembrolizumab and paclitaxel in HR+/HER2-negative, PAM50 non-luminal, metastatic breast cancer (MBC). Methods TATEN is a single-arm, multicenter phase II study evaluating pembrolizumab in combination with paclitaxel in patients with HR+/HER2-, PAM50 non-luminal, MBC. Key inclusion criteria include progression to prior CDK4/6 inhibitors, presence of measurable disease by RECIST V1.1, no prior chemotherapy for MBC, and ECOG 0-1. Patients receive pembrolizumab at 200 mg every 3 weeks (on D1 of each 21-day cycle, beginning at cycle 1) in combination with weekly paclitaxel at 80 mg/m2, beginning at cycle 2. The primary endpoint is to evaluate overall response rate (ORR), defined as the rate of complete (CR) and partial response (PR) according to RECIST V1.1. Secondary endpoints include clinical benefit rate (CBR; CR + PR + stable disease >24 weeks), progression free survival, overall survival, safety, and predictive biomarkers. Tumor samples collected during advanced/metastatic disease are mandatory to assess PAM50 and other translational endpoints. This study had a planned interim analysis after 15 patients were evaluable for ORR based on a Simon’s two stage design with 80% power and a type I error rate of 0.05. Stage I of the trial would be considered successful if at least 6 patients achieved a PR and/or CR. In that case, the trial would recruit up to 46 evaluable patients for a target ORR ≥ 41. Here we report results from the patients who received at least one dose of combination treatment and had a first, post-baseline, tumor assessment according to RECIST v1.1 (evaluable population). Results From July 2020 to December 2021, 119 patients were screened, and 25 PAM50 non-luminal tumors were identified (21%). From these, 17 (68%) patients were recruited, and 15 were evaluable for primary endpoint. Two patients discontinued the trial before the first dose of pembrolizumab and paclitaxel, because of clinical progressive disease (PD). Baseline patient characteristics were as follows: median age 53 years (range: 40-77), ECOG 0 52.9%, de novo MBC at diagnosis 29.4%, and visceral disease 64.7% (including 53.3% with liver metastasis). Ten patients had received paclitaxel treatment in the adjuvant setting. Regarding PAM50 intrinsic subtype, two patients had basal-like and 13 HER2-E tumors. At the time of data cut-off (May 17,2022), 8 patients (53.3%) had stopped their treatment because of PD and 2 (13.3%) due to toxicity. Five patients (33.3%) were still on treatment. The ORR was 53.3 % (8 of 15, 95% CI 26.6-78.7), meeting the pre-specified ORR for the first stage of the trial. The CBR was 86.6% (13 of 15, 95%CI 59.5-98.34), and median PFS was 7.5 months (95% CI: 5.6 – 10.2). Overall, all patients experienced treatment-related adverse events (TRAEs) of any grade, while 53.3% of patients experienced grade 3 TRAEs. No grade 4 or 5 TRAEs were reported in the evaluable population. Correlative analysis including gene expression analysis and centralized TILs scoring and PD-L1 IHC will be presented. Conclusions The first stage of TATEN combining pembrolizumab with paclitaxel after progression to CDK4/6 inhibitors in patients with HR+/HER2-negative, PAM50 non-luminal MBC met its pre-specified endpoint. Completion of the stage II part of the trial with the inclusion of up to 46 patients is warranted to assess the activity of this combination in this group of patients. Correlative studies to find predictive biomarkers of response to this regimen are ongoing and will be presented at the meeting. This study was funded by MSD. Citation Format: Aleix Prat, Tomás Pascual, Montserrat Muñoz, Cristina Hernando, Silvia Vazquez, Salvador Blanch, Manuel Alva, Mafalda Oliveira, Esther Sanfeliu, Lorea Villanueva, Fara Brasó-Maristany, Nuria Chic, Eva Ciruelos. TATEN TRIAL (SOLTI-1716) Targeting non-Luminal disease by PAM50 with pembrolizumab + paclitaxel in Hormone Receptor-positive/HER2-negative (HR+/HER2-) metastatic breast cancer (MBC): interim analysis [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P3-06-02.

Abstract PD11-04: PD11-04 Primary results of SOLTI-1503 PROMETEO phase 2 trial of Combination of Talimogene Laherparepvec (T-VEC) with Atezolizumab in patients with residual breast cancer after standard neoadjuvant multi-agent chemotherapy

Abstract Background: Residual disease (RD) following neoadjuvant chemotherapy (NAC) in early HER2-negative breast cancer (BC) remains an unmet medical need. However, no therapies to date have tested their activity directly in chemo-resistant RD. Here, we hypothesized that combining an oncolytic virus such as T-VEC with atezolizumab may offer clinical benefit in patients (pts) with RD after standard NAC. To our knowledge, PROMETEO is the first trial that examines the activity of immunotherapy in pts with RD prior to surgery. Methods: PROMETEO (NCT03802604) is a single-arm, open-label, multicenter phase II trial. Women with triple-negative BC (TNBC) or hormone receptor-positive/HER2-negative (HR+/HER2-) BC with baseline (i.e., before NAC) ki67 ≥ 20% were eligible. RD was confirmed with a magnetic resonance imaging (MRI) showing a tumor diameter ≥ 10 mm and a core-biopsy detecting the presence of invasive cells. Before surgery, T-VEC was administered intratumorally on week 1 (106 pfu/mL), then in week 4 and every 2 weeks thereafter (108 pfu/mL) for 4 injections. Atezolizumab (840 mg) was administered intravenously every 2 weeks for 4 infusions, starting at week 4. Surgery was performed in < 3 weeks after completing the treatment. The primary objective was to evaluate the efficacy of the combination, measured by the rate of residual cancer burden (RCB) class 0/1 at surgery. Tumor samples collected at 5 timepoints (before NAC, during screening period, after first dose of T-VEC, after first dose of T-VEC and atezolizumab and at surgery) were mandatory to assess gene expression, tumor-infiltrating lymphocytes (TILs), immune cells PD-L1 IHC (SP142), tumor mutational burden (TMB) by FoundationOne and other translational endpoints. Results: Between Dec 2018 to Feb 2022, 28 pts were enrolled: 20 pts with HR+/HER2- disease and 8 pts with TNBC. Median age was 47 (range 31-71) and 71% of pts were premenopausal. At diagnosis before NAC, clinical stage II disease represented 60.7%, cN+ 60.7%, median Ki-67 was 37.5% (range 20%-95%), high TILs (≥10%) 37%, median TMB was 3 (0-19) and only 1 of 27 pts (3.7%) had a PD-L1-positive tumor. After NAC, mean tumor size by MRI was 28.3 mm (10-93). Two pts discontinued from the trial (1 withdrawal of consent and 1 COVID infection). The completion of 5 cycles of treatment was achieved by 73% of pts. The overall RCB-0/1 rate was 25% (7 of 28, 95% IC 10.7 – 44.9%), all with RCB 0 (pathologic complete response [pCR]). The pCR rate was 30% in HR+/HER2- disease and 12.5 % in TNBC. Radiological response by MRI was achieved by 3 of 28 pts (10.7%). Interestingly, none of the 7 pts with a pCR had radiological response (stable disease n=5, progressive disease [PD] n=2). Six pts (21.4%) had radiological PD and had RCB 2/3. Overall, 27 (96%) patients had at least one treatment-emergent adverse event (TEAE) of any grade. Most common grade 1 or 2 AEs were fever (11 pts, 39.3%), ALT increased (9 pts, 32.1%), AST increased (8 pts, 28.6%), arthralgia (6 pts, 21.4%) and anemia (6 pts, 21.4%). Grade 3 reversible neutropenia occurred in 1 patient. Across all pts, significant increases (p< 0.001) in TILs, immune genes and immune PDL1+ cells were observed after 1 dose of TVEC, 1 dose of the combination and at surgery. Intrinsic subtype changes at surgery occurred in 73.1% of cases, mostly (46.1%) Luminal A/B converting to Normal-like. At surgery, 19 of 26 (73.1%) of tumors were PDL1+. Conclusions: Two months of T-VEC in combination with atezolizumab induced a pCR in a subgroup of pts with chemoresistant HER2- breast cancer. This effect is probably related to the immune activation provoked by the combined treatment. Interestingly, a high discrepancy was observed between the pre-surgical radiological imaging and the actual surgical pathological report. Pre-operative window-of-opportunity trials in this context might provide important clues regarding the activity of novel treatment strategies. Citation Format: Tomás Pascual, Maria Vidal, Juan Miguel Cejalvo, Estela Vega, Esther Sanfeliu, Sergi Ganau, Ana Julve, Esther Zamora, Ignacio Miranda, Ana Delgado, Begoña Bermejo, Luis de la Cruz-Merino, Manel Juan, Patricia Galván, Xavier Gonzalez-Farré, Juan Manuel Ferrero-Cafiero, Patricia Villagrasa, Mafalda Oliveira, Aleix Prat. PD11-04 Primary results of SOLTI-1503 PROMETEO phase 2 trial of Combination of Talimogene Laherparepvec (T-VEC) with Atezolizumab in patients with residual breast cancer after standard neoadjuvant multi-agent chemotherapy [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD11-04.

Abstract P2-23-17: Programmed death ligand-1 expression in triple-negative breast cancer from Nigeria

Abstract Introduction: The incidence of triple negative breast cancer (TNBC) in West Africa appears to mirror the higher incidence of the disease among African American women in the United States. However, there remains a paucity of molecular data on TNBC from sub-Saharan Africa, despite the emergence of effective immunotherapies. Methods: Consecutive patients diagnosed with invasive breast cancer between March 2018-Jan 2020 were identified from a prospective clinical database and paired biobank at Obafemi Awolowo University Teaching Hospital (OAUTH). All specimens were processed and fixed in formalin within 60 minutes of excision by a trained pathologist. Tissue sections (4μm thick) representative of tumor were selected for routine evaluation of estrogen, progesterone and human epidermal growth factor receptor-2 expression by immunohistochemistry. This was performed at OAUTH with adequate controls according to the ASCO/CAP guidelines and verified at an outside institution for quality assurance. Additional sections from the FFPE blocks of TNBC specimens were further stained using the Dako PharmDx 22C3 PD-L1 commercial assay according to manufacturer protocols at Dalhousie University. External on-slide controls included tonsil, PD-L1 negative TNBC, and PD-L1 positive TNBC. PD-L1 expression was scored using the combined positive score (CPS), which is the number of 22C3 staining tumour cells, lymphocytes, and macrophages divided by the number of viable tumour cells, multiplied by 100. The threshold for a positive result was a CPS of ≥10 as per manufacturer instructions and institutional protocol. Research ethics board approval as well as data and material transfer agreements between institutions was obtained for this study. Results: From 85 cases, 32 were TNBC (37.6%). The mean age and BMI were 49.6±SD 7.7 and 26.2±5.7, respectively. The majority of patients presented with locally advanced disease (64.2% Stage III, 14.2% Stage IV). Seventy-nine percent (78.5%) of patients received an average of five cycles of neoadjuvant chemotherapy (SD 2.3). From 32 TNBC specimens, 27 had available FFPE tissue blocks, and of those, 24 had interpretable PD-L1 IHC for inclusion in the analysis. A total of 37.5% (9/24) of cases demonstrated a CPS ≥10. Conclusions: Over a third of breast cancer specimens in this Nigerian cohort were triple negative, 37.5% of which had PD-L1 CPS scores of ≥10. These results suggest a large proportion of patients in Nigeria may benefit from access to immunotherapy. This is the first reported incidence of PD-L1 expression in breast cancer from sub-Saharan Africa. Citation Format: Olalekan Olasehinde, Funmilola Wuraola, Aleksandra Kajetanowicz, Gilllian Bethune, Marcia Edelweiss, Peter Ntiamoah, Oluwole Odujoko, Avinash Sharma, Victoria Mango, Peter Kingham, Olusegun Alatise, Gregory Knapp. Programmed death ligand-1 expression in triple-negative breast cancer from Nigeria [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-23-17.

SETD2 gene expression and the molecular landscape of colorectal cancer (CRC).

184 Background: SETD2, a key methyltransferase modulating histone 3 gene transcription, has been shown to act as a tumor suppressor gene by reducing oxidative stress, colonic inflammation and tumorigenesis in animal models. SETD2 gene expression has been reported to be significantly downregulated in CRC and linked with poorer patient survival. Additionally, SETD2 plays an important role in DNA repair and loss of function mutations have been associated with increased tumor mutational burden (TMB), mismatch repair (MMR) deficiency, and benefit from immunotherapy. Hence, we aimed to characterize the molecular features associated with SETD2 gene expression in CRC. Methods: 15,425 CRC tumors tested at Caris Life Sciences (Phoenix, AZ) with NextGen Sequencing on DNA (592 genes or whole exome sequencing), RNA (whole transcriptome sequencing), and IHC were analyzed. SETD2-high and -low expression were defined as ≥ top and < bottom quartile of SETD2 transcripts per million (TPM), respectively. Cell infiltration in the tumor microenvironment (TME) was estimated by QuantiSEQ. Mann-Whitney U and X2/Fisher-Exact tests were applied where appropriate, with P-values adjusted for multiple comparisons ( q < .05). Gene expression profiles were analyzed for transcriptional signatures predictive of response to immunotherapy (T cell-inflamed) and MAPK pathway activation (MPAS). Real-world overall survival information was obtained from insurance claims data and Kaplan-Meier estimates were calculated for molecularly defined patients. Results: SETD2 expression was significantly increased in left-sided/rectal compared to right-sided tumors (median TPM [mTPM] 55.8 vs 51.1, q < .001). SETD2 mutations were associated with reduced SETD2 expression in pMMR/MSS CRC (mTPM 37.9 vs 54.3 in WT, q < .001), although not statistically significant in dMMR/MSI-H CRC (mTPM 43.6 vs 51.7 in WT, P = .17). Compared to SETD2-high tumors, SETD2-low was associated with increased rates of TMB-high (10.4% vs 8.2%, P = .009), dMMR/MSI-H (7.3% vs 5.6%, P = .02), and PD-L1 IHC levels (4.4% vs 2.5%, q < .002). Only minor differences in gene mutation and copy number rates were observed between SETD2-high and -low tumors , whereas SETD2-high TME was associated with increased immune cell infiltration, including neutrophils, B cells, NK cells, M2 macrophages, and dendritic cells ( q < .05). SETD2-high was also associated with increased T cell-inflamed and MPAS signatures (152% and 159% median increase, respectively, q < .001), regardless of tumor MMR status. Among dMMR/MSI-H CRC, SETD2-high tumors receiving immune checkpoint inhibitors had longer time-on-treatment (HR: 0.39, 95% CI: 0.2-0.76, P = .005) and a trend towards longer OS (HR: 0.29, 95% CI: 0.07-1.2, P = .069). Conclusions: Our data show distinct immune biomarkers and TME cell infiltration associated with SETD2 gene expression in CRC. These findings support a key role for SETD2 in modulating anti-tumor immunity and TME.

The impact of combined PD-L1 positive score on clinical response to nivolumab in patients with advanced esophageal squamous cell carcinoma.

Nivolumab is recommended for patients with advanced esophageal squamous cell carcinoma (aESCC) refractory or intolerant to fluoropyrimidine- and platinum-based chemotherapy regardless of the tumor proportion score (TPS). However, the role of combined positive score (CPS) in predicting nivolumab efficacy remains unclear. We aimed to study whether TPS or CPS is a more suitable biomarker for predicting nivolumab efficacy in these patients. We retrospectively collected data from patients with aESCC treated with fluoropyrimidines and platinum and subsequently received nivolumab monotherapy between January 1, 2014 and September 15, 2020. Next, we evaluated the efficiencies of TPS and CPS in predicting the clinical response to nivolumab using PD-L1 IHC 22C3 pharmDx assay. This study included 50 patients (CPS groups: ≥ 10/1-10/ < 1, n = 24/18/8, respectively; TPS groups, ≥ 10%/1%-10%/ < 1%, n = 17/8/25, respectively). The median progression-free survival was 3.2, 2.5, and 1.5months in the ≥ 10, 1-10 [hazard ratio (HR) vs. CPS of ≥ 10 group, 1.01; p = 0.98; adjusted HR, 1.33; p = 0.56], and < 1 CPS groups (HR vs. CPS of ≥ 10 group, 3.44; p = 0.006; adjusted HR, 1.67; p = 0.41), respectively. For the patients with CPS of ≥ 10/1-10/ < 1 and TPS of ≥ 10%/1%-10%/ < 1%, the objective response rate was 30%/25%/0% and 36%/0%/19% and the disease control rate was 60%/50%/12% (p = 0.06) and 65%/40%/38% (p = 0.30), respectively. This study suggests that a CPS of < 1 is not a strong predictor of efficacy but can predict the absence of response to nivolumab in patients with aESCC.