PD-L1 Positive Tumors Research Articles

Erdafitinib (ERDA) vs ERDA plus cetrelimab (ERDA+CET) for patients (pts) with metastatic urothelial carcinoma (mUC) and fibroblast growth factor receptor alterations (FGFRa): Final results from the phase 2 Norse study.

4504 Background: First-line (1L) therapy for cisplatin (cis)-ineligible pts with mUC remains an unmet need and includes alternative chemotherapy or anti-PD-(L)1 monotherapy for PD-L1 positive tumors. FGFRa tumors are enriched for the luminal 1 subtype with lower immune cell infiltrate and potential lower benefit from anti-PD-(L)1 monotherapy. We studied ERDA+CET in 1L, FGFRa, mUC to determine the potential impact in this setting (NCT03473743). Methods: Pts aged ≥ 18 y with mUC, susceptible FGFRa and measurable disease (no prior systemic therapy for mUC, cis-ineligible) were randomized 1:1 to once-daily ERDA 8 mg (with pharmacodynamically guided uptitration (UpT) to 9 mg) or ERDA 8 mg (no UpT) + IV CET 240 mg every 2 weeks (wks) at cycles 1-4 and 480 mg every 4 wks thereafter. Primary endpoints were investigator-assessed overall response rate (ORR) per RECIST 1.1 and safety; secondary included duration of response (DOR), time to response (TTR), progression free survival (PFS) and overall survival (OS). There were no pre-planned statistical comparisons between treatment arms. Results: As of the data cutoff, 87 pts were randomized and treated; 44 to ERDA+CET and 43 to ERDA: median age was 69 vs 72 y; visceral metastases were present in 60.0 vs 63.6%. Median follow-up time was 14.2 months (mo). ORR for ERDA+CET was 54.5% with 6 (13.6%) CRs and 12 mo OS 68%. 11/24 responders were ongoing. ORR for ERDA was 44.2% with 1 CR and 12 mo OS 56%. 9/19 responders were ongoing. 4 pts in each arm were PD-L1 positive. 3/4 (75%) PD-L1 positive pts responded to ERDA+CET vs 0 for ERDA. The most frequent treatment-emergent AEs (any grade) were hyperphosphatemia (68.9 vs 83.7%), stomatitis (59.1 vs 72.1%) and diarrhea (45.5 vs 48.8%) for ERDA+CET and ERDA respectively. Grade ≥3 treatment-related AEs occurred in 45.5 (ERDA+CET) and 46.5% (ERDA) of pts. There was one CET-related death in ERDA+CET secondary to pulmonary failure. Conclusions: Combination ERDA+CET demonstrated clinically meaningful activity and was well tolerated. These results, in 1L cis-ineligible pts, support previously described activity of ERDA monotherapy in FGFRa mUC. The safety profile was consistent with the known profile for ERDA and CET with no additive toxicity for the combination. Clinical trial information: NCT03473743 . [Table: see text]

Quantitation of the PD-1/PD-L1 axis in non-small cell lung cancer by immuno-multiple reaction monitoring.

e14656 Background: Immuno-oncology revolutionized lung cancer treatment, but predictive biomarkers of response to checkpoint inhibitors (CPI) are still lacking. Only 50% of PD-L1 positive tumors by immunohistochemistry (IHC) respond to anti-PD-L1 treatment. Analytical variability and post-translational modifications (PTM) of the PD-1 signaling associated proteins (e.g.: glycosylation), can explain some of this discrepancy. Plus, the tumor immune microenvironment (TME) is complex and PD-L1 IHC alone is a flawed surrogate its status. Mass spectrometry based technologies have the potential to overcome these challenges by integrating sensitivity, specificity and absolute quantitation of proteins and PTMs in a standardized fashion. Here, we demonstrate the advantages of using anti-peptide antibodies to purify surrogate peptides followed by liquid-chromatography (LC) and multiple reaction monitoring (MRM), herby termed as iMRM, to gain new insight into the TME. Methods: To determine the concentration of PD-L1, PD-1, PD-L2, NT5E, LCK and ZAP70, we used unique and well detectable proteolytic peptides as surrogates. Our previously described protocol (ASCO 2022, #377181) allows robust quantitation of 13 peptides and monitors the glycosylation status of PD-L1, PD-L2, and PD-1. NSCLC samples were either fresh frozen (n = 42) or FFPE (n = 77) and sometimes both (n = 17). PD-L1 quantitation by iMRM was compared to PD-L1 IHC 22C3. Results: This multiplexed iMRM assay successfully quantified the PD-1/PD-L1 axis proteins in 96% of NSCLC patients (61/63). PD-L1 glycosylation levels ranged from 82 to 100% (n = 69, median = 100%, SD = 3.7%). Only PD-1 was significantly different between the fresh frozen (mean = 11±6 amol/µg total protein) and FFPE group (mean = 5±2 amol/µg total protein, ρ = 0.0001), all other peptides showed comparable levels. In our 17 matched FF/FFPE samples, PD-L1 moderately correlated (R = 0.45, ρ = 0.045) and the other peptides did not correlate (R < 0.03). Intra/intertumoral heterogeneity, differences in cellularity and tumor origin likely contributed to this discrepancy. IMRM results correlated moderately (R = 0.56, ρ < 0.01) with PD-L1 IHC. Most of these patients were not CPI-treated, but survival data was available. A trend was noted between the concentration of certain targets and patient survival. Linear regression was used to establish a cut-off for each peptide from which an immunoscore was calculated. The immunoscore could predict long-term survival (accuracy 75.4%) irrespective of tumor staging, grade or subtype and survival was significantly associated with the immunoscore (log-rank ρ = 0.005). Conclusions: Our iMRM workflow provides a new understanding of the TME in NSCLC through the PD-1/PD-L1 axis with an easy-to-read immunoscore. A set of 60 tumors from CPI-treated patients is currently being processed to validate the clinical utility of the assay in relation with CPI-response.

Abstract 5184: Anti-HVEM mAb therapy improves antitumoral immunity both in vitro and in vivo, in a novel transgenic mouse model expressing human HVEM and BTLA molecules challenged with HVEM expressing tumors

Abstract TNFRF-14/HVEM is the ligand for BTLA and CD160 negative immune co-signaling molecules as well as viral proteins. Its expression is dysregulated with an overexpression in tumors and a connection with tumors of adverse prognosis. We developed C57BL/6 mouse models co-expressing human huBTLA and huHVEM as well as antagonistic monoclonal antibodies (mAbs) that completely prevent the interactions of HVEM with its ligands. Here, we show that the anti-HVEM18-10 mAb increases primary human αβ-T cells activity alone (CIS-activity) or in the presence of HVEM-expressing lung or colorectal cancer cells in vitro (TRANS-activity). Anti-HVEM18-10 synergizes with anti-PD-L1 mAb to activate T cells in the presence of PDL-1 positive tumors, but is sufficient to trigger T cell activation in the presence of PD-L1 negative cells. In order to better understand HVEM18-10 effect in vivo and especially disentangle its CIS and TRANS effects, we developed a knock-in (KI) mouse model expressing human BTLA (huBTLA+/+) and a KI mouse model expressing both human BTLA and human HVEM (huBTLA+/+/huHVEM+/+ (DKI)). In vivo pre-clinical experiments performed in both mouse models showed that HVEM18-10 treatment was efficient to decrease human HVEM+ tumor growth. In the DKI model, anti-HVEM 18-10 treatment induces a decrease of exhausted CD8+ T cells and regulatory T cells and an increase of Effector memory CD4+ T cells within the tumor. Interestingly, mice which completely rejected tumors (± 20%) did not develop tumors upon re-challenge in both settings, therefore showing a marked T cell-memory phenotype effect. Altogether, our preclinical models validate anti-HVEM18-10 as a promising therapeutic antibody to use in clinics as a monotherapy or in combination with existing immunotherapies (anti-PD1/anti-PDL-1/anti-CTLA-4). Citation Format: Laurent GORVEL, Clemence Demerle, Marielle Mello, Sonia Pastor, Clara Degos, Ana Zarubica, Fabien Angelis, Frederic Fiore, Jacques Nunes, Bernard Malissen, Laurent Greillier, Geoffrey Guittard, Herve Luche, Fabrice Barlesi, Daniel Olive. Anti-HVEM mAb therapy improves antitumoral immunity both in vitro and in vivo, in a novel transgenic mouse model expressing human HVEM and BTLA molecules challenged with HVEM expressing tumors. [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 5184.

Abstract PD11-11: PD11-11 Results from ALICE – Atezolizumab Combined with Immunogenic Chemotherapy in Patients with Metastatic Triple Negative Breast Cancer, a Randomized Phase IIb Trial

Abstract Background: Immune checkpoint inhibitors (CPI) have shown efficacy against metastatic triple negative breast cancer (mTNBC), but only for PD-L1 positive tumors. It is not known if so-called immunogenic chemotherapies may yield clinical relevant synergies with CPI. We addressed these issues, by conducting a trial evaluating atezolizumab (anti-PD-L1) in combination with doxorubicin, which has been reported to provoke immunogenic cell death, and low-dose metronomic cyclophosphamide, which has been reported to counter immunosuppressive cells. The pegylated liposomal form of doxorubicin (PLD) was selected to avoid steroids and allow for long term therapy in responders. To our knowledge, this is the first randomized trial reporting on the concomitant addition of CPI to antracyclines in mTNBC. Methods: The trial enrolled patients with mTNBC and maximum one previous line of chemotherapy in the metastatic setting. Patients were randomized 2:3 into arm A (n=28), receiving chemotherapy alone, or arm B (n=40), receiving chemotherapy in combination with atezolizumab (840 mg every 2nd week). The chemotherapy consisted of PLD (20mg/m2 every 2nd week) + oral cyclophosphamide (cyclo; 50mg/day, 2/4 weeks) in both arms. The per protocol (PP) population was defined as patients receiving > 3 doses of atezolizumab and >2 doses of PLD. The primary efficacy endpoint was progression-free survival (PFS) in the PP population. The protocol power analysis focused on durable response, as measured by 15 months PFS. Safety, a co-primary endpoint, was evaluated in all patients that started therapy (Full Analysis Set; FAS). Secondary endpoints included PFS in FAS, objective response rate (ORR), clinical benefit rate (CBR), durable response rate (>6 months; DRR), overall survival (OS) and biomarkers. PD-L1 status was determined retrospectively by the Ventana SP142 assay, as tumor-infiltrating immune cells with cut-off ≥ 1%. Efficacy data are given in the PP population unless stated otherwise. Hazard ratios (HR) are given with 95% confidence intervals (CI). Results: A total of 68 patients started therapy (FAS), of which 59 were in the PP population and 57% had not received previous chemotherapy in the metastatic setting. PFS was significantly improved in arm B compared to arm A in both the PP population (HR 0.57; CI 0.33-0.99; p=0.0477) and in the FAS (HR 0.56; CI 0.33-0.95; p=0.0326). Median PFS was 4.3 months in arm B versus 3.5 months in arm A. The progression-free proportion after 15 months was 14.7% (CI 6.4-30.1%) in arm B versus 0% in arm A. The ORR was 30.6%/21.7%, CBR was 52.8%/43.5% and DRR was 13.9%/4.3% in arm B/A. The PFS advantage was observed for both PD-L1+ (n=27; HR 0.58) and PD-L1- subjects (n=31; HR 0.66). All five patients without progression after 15 months belonged to arm B, and three out of these patients were PD-L1 negative. Serious adverse events occurred for 48% in arm B and 29% in arm A (FAS). The most common immune related adverse events of any grade in arm B/A were hypothyroidism (10.0%/7.1 %), pneumonitis (10.0%/3.6%), hyperthyroidism (5.0%/7.1%) and rash (7.5%/3.6%). Further biomarker analyses and assessments of immunological changes during therapy are ongoing. Conclusions: The addition of atezolizumab to PLD and low-dose metronomic cyclophosphamide significantly improved PFS. A benefit was indicated also in patients with PD-L1 negative disease. The combination regimen was well tolerated with no new safety signals. Results from the ongoing analyses of consecutive tumor and blood samples will be important to assess the hypothesized immunological effects of the chemotherapy and to investigate biomarkers associated with the response to the combined treatment. Citation Format: Jon Amund Kyte, Andreas H. Røssevold, Nikolai K. Andresen, Christina Annette Bjerre, Bjørnar Gilje, Erik Hugger Jakobsen, Sunil Xavier Raj, Ragnhild Sørum Falk, Elin Borgen, Thea Jahr, Øystein Garred, Jon Lømo, Randi Margit Mathiesen, Bjørn Naume. PD11-11 Results from ALICE – Atezolizumab Combined with Immunogenic Chemotherapy in Patients with Metastatic Triple Negative Breast Cancer, a Randomized Phase IIb Trial [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 PD11-11.

Immune checkpoint inhibitors in the peri-operative setting in renal cell carcinoma: A meta-analysis of the randomized clinical trials.

682 Background: Localized and oligometastatic resectable renal cell carcinoma (RCC) have moderate to high rates of relapse after surgery and evidence regarding the efficacy of perioperative treatments is conflicting. The risk of relapse varies across studies and there is a need to define the benefit/risk of immune checkpoint inhibitors (ICI) in this setting to optimize their use. Methods: A meta-analysis of the randomized phase 3 trials of peri-operative treatment with anti-PD-1/PD-L1 agents or anti-PD1/antiCTL4 in combination was conducted. The primary outcomes of interest were disease-free survival (DFS) and overall survival (OS). Secondary outcomes of interest were the proportion of grade 3-4 adverse events (AE) according to CTCAE 5.0. Subgroup analyses were performed according to clinically relevant characteristics. Statistical heterogeneity assumption was evaluated by the χ²-based Cochran’s Q test and quantified with the I² statistic. All statistical analyses were performed using Stata software (StataCorp LLC), version 16. Results: Published results of 4 phase 3 trials were included, involving 3393 patients. 1695 patients received ICI (anti-PD1: 900 patients; anti-PD-L1 390 patients, antiPD1/anti-CTLA4 405 patients) while 1712 received no active treatment (1297 placebo, 415 observation). ICI did not show to increase DFS (Hazard ratio (HR) 0.84 95% CI 0.69-1.03 p 0.10) or OS (HR 0.73 95% CI 0.40-1.34 p 0.31). High-grade AEs were 2.6 times more frequent in the immunotherapy arm (OR 2.64 95% CI 1.54 – 4.68 p < 0.001) while high grade treatment-related AEs were 8 times more frequent in the experimental arm (OR 8.60 95% CI 3.23-22.91 p < 0.001). Interestingly, subgroup analyses showed statistically significant differences favoring the experimental arm in females (HR 0.72 95% CI 0.55-0.93 p 0.01), in patients with sarcomatoid differentiation (HR 0.59 95% CI 0.403-0.88 p 0.010) and PD-L1 positive tumors (HR 0.74 95% CI 0.61-0.90 p 0.003). No significant effect was found in patients according to age, type of nephrectomy (radical vs. partial), and stage (M1 without evidence of disease vs M0 patients). Conclusions: The introduction of anti-PD-(L)1 +/- anti-CTLA-4 agents in the adjuvant setting of RCC might benefit selected RCC patients, although with increased toxicity. Longer follow-up of the conducted studies is needed to establish a potential benefit in long-term survival.

The redirected killing of PD-L1 positive tumor cells by the expanded mucosa-associated invariant T (MAIT) cells is mediated with a bispecific antibody targeting TCR Vα7.2 and PD-L1

Pan-T cell targeting by CD3-based T cell engagers has brought program-shift treatment and management of blood tumors. However, these modalities have been shown to provoke all types of T cells leading to cytokine storm syndrome, and activate Treg cells. Thus, modulating and potentiating the antitumor responses of a specific T cell subset was encouraged. We initially found that high purity of mucosa-associated invariant T (MAIT) cells could be expanded by the combination of plate-immobilized Vα7.2 mAb (Clone 3C10) and IL2 plus IL15. Then, we generated a novel anti-Vα7.2 TCR bsAb, Vα7.2 x PD-L1, to invoke the anti-tumor potency of these expanded MAIT cells. Furthermore, our data have demonstrated that Vα7.2 x PD-L1 could mediate the cell-to-cell conjunction between MAIT cell and tumor cell line, selectively elicit the activation, cytokine production, degranulation, and cytotoxicity of the expanded MAIT cells in the presence of target cell only. Collectively, this proof-of-concept study provides a new tool to explore the clinical potential of MAIT cells in fighting against PD-L1 positive solid tumors and suggests additional encouragement in designing novel T cell engagers targeting TCR alpha chain specific innate-like T cells subsets, other than pan CD3+ T cells.

Evaluation of the clinical molecule anti-human-PD-L1/IL-15 KD033 in the human-PD-1/PD-L1-expressing murine model demonstrates PD-L1 targeting of IL-15 in vivo

KD033 is a clinical-stage immunocytokine composed of a high-affinity anti-human-PD-L1 antibody and the human IL-15/ IL-15 receptor sushi-domain complex. We have previously shown that KD033-surrogate, the anti-mouse-PD-L1/IL-15 immunocytokine, was efficacious in several syngeneic murine tumor models including those that were refractory to anti-PD-1/PD-L1 checkpoint blockers. KD033-surrogate showed better efficacy than the combination treatment of its component, anti-PD-L1 antibody with the non-targeting IL-15. KD033-surrogate was also efficacious in both low and high PD-L1-expressing tumors. In this study, we have utilized double knock-in mice expressing functional human PD-1/PD-L1 to show that the clinical molecule, KD033, reproduced the anti-tumor efficacy observed with KD033-surrogate in the syngeneic models. KD033 was equally efficacious in reducing the growth of human-PD-L1 positive (hPDL1+) and negative (hPDL1-) MC38 murine tumors. We observed similar peripheral pharmacodynamics changes in KD033-treated mice bearing either hPDL1+ or hPDL1- MC38 tumors. However, different transcriptomic profiles were observed between KD033-treated hPDL1+ and hPDL1- MC38 tumors with marked changes involving mostly downregulated genes in hPDL1- tumors in addition to the immune-related genes changes observed in both hPDL1+ and hPDL1- MC38 tumors. Cytotoxic and myeloid cell signatures were upregulated in both tumors with relatively greater increases observed in hPDL1- MC38 tumors. These effects of KD033 treatment in PD-L1 positive and negative tumors demonstrate the role of PD-L1 in targeting of IL-15 cytokine in vivo.

Anti PD-1/Anti PDL-1 Inhibitors in Advanced Gastroesophageal Cancers: A Systematic Review and Meta-Analysis of Phase 2/3 Randomized Controlled Trials.

Importance: Immune checkpoint inhibitors (ICI) have revolutionized the treatment for gastroesophageal cancers (GEC). It is important to investigate the factors that influence the response to anti-PD-1/PD-L1 ICIs. Objective: To assess the benefits of PD-1/PD-L1 ICIs in advanced GEC and perform subgroup analysis to identify patient populations who would benefit from ICI. Data sources: PubMed, Embase, Scopus, and the Cochrane Library databases were systematically searched from database inception to September 2021 for all relevant articles. We also reviewed abstracts and presentations from all major conference proceedings including relevant meetings of the American Society of Clinical Oncology (ASCO), and the European Society for Medical Oncology (ESMO) during the last four years (2018 to 2021) and reviewed citation lists. Study selection, data extraction, and synthesis: Full articles and presentations were further assessed if the information suggested that the study was a phase 2/3 randomized controlled trial (RCT) comparing PD-1/PD-L1 inhibitor either alone, or in combination with standard therapy vs. standard therapy in advanced GEC. The full text of the resulting studies/presentations and extracted data were reviewed independently according to PRISMA guidelines. Main outcomes and measures: The main outcomes were OS, PFS, and treatment-related adverse events (TRAEs). Results: A total of 168 studies were assessed for eligibility, and 17 RCTs with 12,312 patients met the inclusion criteria. There was an OS benefit in the overall population with ICIs (HR 0.78; 95% CI 0.73–0.83 p < 0.001). Immunotherapy showed better OS benefit in males (HR 0.77 95% CI 0.72–0.83; p < 0.001) than females (HR 0.89; 95% CI 0.80–0.99 p < 0.03), esophageal primary tumors (HR 0.70 95% CI 0.64–0.76 p < 0.001) vs. gastric cancer (HR 0.84 95% CI 0.74–0.94 p 0.002) or GEJ cancer (HR 0.84 95% CI 0.72–0.98 p 0.024) and in squamous cell carcinoma (HR 0.71 95% CI 0.66–0.77 p < 0.001) vs. adenocarcinoma (HR 0.85 95% CI 0.78–0.93 p < 0.001). PD-L1 positive patients seemed to benefit more (HR 0.74 95% CI 0.67–0.82 p < 0.001) compared to PD-L1 negative patients (HR 0.86 95% CI 0.74–1.00 p < 0.043), and Asians showed OS benefit (HR 0.76 95% CI 0.67–0.87 p < 0.001) compared to their White counterparts (HR 0.92 95% CI 0.74–1.14; p 0.424). Conclusions and relevance: ICIs improve survival in advanced GEC without significantly increasing the side effects. However, certain subgroups of patients such as males, Asians, and those with esophageal primary, PD-L1 positive tumors and squamous cell carcinoma benefit more from such treatments. Further translational research is needed to understand the mechanistic links and develop new biomarkers.

LBA32 Efficacy and safety of GX-188E, a therapeutic DNA vaccine, combined with pembrolizumab in HPV 16- and/or 18- positive advanced cervical cancer (phase II): Safe and effective in both PD-L1 positive and negative

GX-188E (tirvalimogene teraplasmid) is a therapeutic DNA vaccine that encodes HPV-16 and HPV-18 E6 and E7 and induces HPV-specific T-cell responses. Pembrolizumab was approved for the treatment of advanced cervical cancer, based on an objective response rate (ORR) of 14.3% in patients with PD-L1 positive (CPS≥1). However, patients who were PD-L1 negative (CPS<1) showed no response to treatment with pembrolizumab. We aimed to investigate whether a combination of GX-188E plus pembrolizumab showed antitumor activity against advanced cervical cancer regardless of PD-L1 expression. In this open-label, single-arm, phase 2 trial, patients with HPV-16 or HPV-18 positive advanced cervical cancer, and who had progressed after standard-of-care therapy were recruited in South Korea. Patients received intramuscular 2 mg GX-188E at weeks 1, 2, 4, 7, 13, 19 and optional dose at week 46, and intravenous pembrolizumab 200 mg every 3 weeks for up to 2 years or until disease progression. The primary endpoint was ORR assessed by the blinded independent central reviewers (BICR) using RECIST v1.1. A total of 65 patients have been enrolled and 60 patients were analyzed as efficacy population based on having at least one post-baseline tumor assessment. Among 60 patients, 36 patients had PD-L1 positive tumors and 24 patients were PD-L1 negative. According to BICR evaluation, 19 of 60 patients (31.7%) achieved best overall response; 6 patients had a complete response and 13 patients had a partial response. Especially, in PD-L1 negative population with 24 patients, this combination treatment showed significant efficacy (25.0% ORR). Median DOR was 12.3 months and median OS was 17.2 months. 22 of 65 patients (33.8%) had treatment-related adverse events (TRAEs) of any grade with three patients (4.6%) presenting with grade 3 or 4 TRAEs. GX-188E vaccine combined with pembrolizumab in advanced cervical cancer was safe and tolerable, and showed significant efficacy compared with pembrolizumab alone particularly in patients with PD-L1 negative. This combination therapy could represent a new potential treatment for this patient population.

1764P The vanishing clinical value of PD-L1 status as predictive biomarker in first-line treatment of urothelial carcinoma of the bladder

Since the introduction of immune checkpoint inhibitors (ICI) for systemic treatment of metastatic urothelial carcinoma of the bladder (UCB) in 2017, the clinical value of programmed cell death 1 ligand 1 (PD-L1) as biomarker remains controversial. In 2018 European Medicines Agency (EMA) restricted approval of first-line pembrolizumab and atezolizumab in Cisplatin-ineligible patients to PD-L1 positive tumors, defined as either combined positive score (CPS) >/=10 or immune cell (IC) score 2/3. We aimed to address the clinical significance of PD-L1 positivity in patients with advanced UCB. Patients with advanced UCB were prospectively enrolled, following radical cystectomy (RC) from January 2018 to December 2020 at our tertiary referral center. Clinical outcome defined as progression free survival (PFS) and overall survival (OS) on systemic treatment was analyzed using the χ2-test, Mann-Whitney-U-test, Kaplan-Meier method and log-rank test. PD-L1-status was analyzed as CPS and IC-score in 141 patients (43.5%) with high-risk (pT3–pT4 and/or N+) or metastatic UCB. While median PFS was 17.5 months (95%CI 11.0-24.1) for PD-L1+ patients who received ICI in 1-L, PD-L1- or PD-L1+ patients who received chemotherapy in 1-L had PFS of 3.8 (IQR 2.3-5.2) and 3.4 months (95%CI 2.9-3.9), respectively.Regardless of treatment, mean OS for PD-L1+ patients was 23.7 months (95%CI 14.9-32.5) vs. 18.2 (95%CI 5.7-30.7) for PD-L1- patients (p=0.592). Median OS with 1-L ICI was 27.2 months (95%CI 12.7-41.7) vs. 17.2 months (95%CI 10.9-23.5) with 1-L chemotherapy (p=0.311). We could show that PFS largely depended on the kind of treatment given to patients, but observed no difference in OS regardless of treatment or PD-L1 status. However, the fact that PD-L1 negative patients responded to anti-PD-L1 therapy, underlines the need for reliable predictive biomarkers for agents targeting this pathway.

Clinical significance and interrelations of PD-L1 expression, Ki-67 index, and molecular alterations in sporadic medullary thyroid carcinoma from a Chinese population.

Immunotherapy shows prospects in treating advanced medullary thyroid carcinoma although controversial reports are present. Recently, histological grading has been applied to medullary thyroid carcinoma by the Ki-67 index, mitotic figures, and tumor necrosis. However, the interrelation of PD-L1 expression, the Ki-67 index, and major genetic alterations of sporadic medullary thyroid carcinoma has not been fully reported. We examined the expression of PD-L1 (SP142 and 22C3) and the Ki-67 index immunohistologically and detected the major genetic alterations by next-generation sequencing in a cohort of sporadic medullary thyroid carcinomas, studied their survival impact, and discussed their interrelation. We identified that a high Ki-67 index (> 2%) and positive RET M918T mutation were correlated with poor disease-free survival but were not correlated with PD-L1 expression. All PD-L1 positive tumors were RET M918T mutation negative, and PD-L1 expression was positively correlated with HRAS mutation. The Ki-67 index was correlated with neither PD-L1 expression nor major genetic alterations. Our results indicate that immunotherapy targeting PD-L1/PD-1 might be more effective for patients with sporadic medullary thyroid carcinoma harboring HRAS mutations.

Efficacy and safety of cadonilimab, an anti-PD-1/CTLA4 bi-specific antibody, in previously treated recurrent or metastatic (R/M) cervical cancer: a multicenter, open-label, single-arm, phase II trial (075)

Objectives: No standard of care in the 2L+ setting for women with recurrent or metastatic (R/M) cervical cancer. Cadonilimab (AK104) is a bi-specific antibody against PD-1 and CTLA4. We assessed the efficacy and safety of cadonilimab in immune checkpoint inhibitor (ICI) naïve patients (pts) with R/M cervical cancer, regardless of PD-L1 status. Methods: This multi-center, open-label, single-arm, phase II study enrolled pts with advanced cervical cancer who had progressed on or after two or fewer previous doublet chemotherapy with or without bevacizumab. Pts received cadonilimab 6 mg/kg every two weeks. The primary endpoint was ORR assessed by the independent radiological review committee (IRRC) per RECIST version 1.1, and the key secondary endpoint was the duration of response (DoR). Results: As of August 5, 2021, 111 pts had received at least one dose of cadonilimab. The median age was 52.0 years (range: 27-73 years). Thirty-six percent of pts had received two prior lines of systemic therapy, 92.8% had squamous cell disease, 56.8% had an ECOG score of 1, 25.0% had received bevacizumab. After median follow-up of 9.63 months (mo) (range: 0.7-21.4), the IRRC-assessed confirmed ORR in 100 pts evaluable for efficacy was 33.0% (95% CI: 23.9%-43.1%), with 12 (12.0%) CR and 21 (21.0%) PR. Median DoR was not reached (range: 0.95+-13.14+ mo); 6- and 12-mo DoR rates were 77.6% and 52.9%, respectively. Median PFS was 3.75 mo (95% CI: 2.00-6.41); 6-and 12 - mo PFS rates were 41.4% and 21.2%, respectively. Median OS was 17.51 mo (95% CI: 11.37 - NE); 6- and 12 - mo OS rates were 80.1% and 64.6%, respectively. Among 64 pts with PD-L1 positive tumors (CPS≥1), the ORR was 43.8% (95% CI: 31.4%-56.7%), the median PFS was 6.34 mo (95% CI: 3.12-11.17), and the median OS was not reached (95% CI: 17.51 mo-NE). Treatment-related adverse events (TRAEs) occurred in 96.4% of 111 patients. Grade 3 to 4 treatment-related adverse events occurred in 28.8% of 111 patients; the most common were anemia (7.2%) and decreased appetite (2.7%). Conclusions: Cadonilimab monotherapy is efficacious and safe as 2L+ treatment of R/M cervical cancer in ICI naïve pts, regardless of PD-L1 status. A phase III confirmatory trial to evaluate cadonilimab plus chemotherapy as 1L treatment for R/M cervical cancer is ongoing. Objectives: No standard of care in the 2L+ setting for women with recurrent or metastatic (R/M) cervical cancer. Cadonilimab (AK104) is a bi-specific antibody against PD-1 and CTLA4. We assessed the efficacy and safety of cadonilimab in immune checkpoint inhibitor (ICI) naïve patients (pts) with R/M cervical cancer, regardless of PD-L1 status. Methods: This multi-center, open-label, single-arm, phase II study enrolled pts with advanced cervical cancer who had progressed on or after two or fewer previous doublet chemotherapy with or without bevacizumab. Pts received cadonilimab 6 mg/kg every two weeks. The primary endpoint was ORR assessed by the independent radiological review committee (IRRC) per RECIST version 1.1, and the key secondary endpoint was the duration of response (DoR). Results: As of August 5, 2021, 111 pts had received at least one dose of cadonilimab. The median age was 52.0 years (range: 27-73 years). Thirty-six percent of pts had received two prior lines of systemic therapy, 92.8% had squamous cell disease, 56.8% had an ECOG score of 1, 25.0% had received bevacizumab. After median follow-up of 9.63 months (mo) (range: 0.7-21.4), the IRRC-assessed confirmed ORR in 100 pts evaluable for efficacy was 33.0% (95% CI: 23.9%-43.1%), with 12 (12.0%) CR and 21 (21.0%) PR. Median DoR was not reached (range: 0.95+-13.14+ mo); 6- and 12-mo DoR rates were 77.6% and 52.9%, respectively. Median PFS was 3.75 mo (95% CI: 2.00-6.41); 6-and 12 - mo PFS rates were 41.4% and 21.2%, respectively. Median OS was 17.51 mo (95% CI: 11.37 - NE); 6- and 12 - mo OS rates were 80.1% and 64.6%, respectively. Among 64 pts with PD-L1 positive tumors (CPS≥1), the ORR was 43.8% (95% CI: 31.4%-56.7%), the median PFS was 6.34 mo (95% CI: 3.12-11.17), and the median OS was not reached (95% CI: 17.51 mo-NE). Treatment-related adverse events (TRAEs) occurred in 96.4% of 111 patients. Grade 3 to 4 treatment-related adverse events occurred in 28.8% of 111 patients; the most common were anemia (7.2%) and decreased appetite (2.7%). Conclusions: Cadonilimab monotherapy is efficacious and safe as 2L+ treatment of R/M cervical cancer in ICI naïve pts, regardless of PD-L1 status. A phase III confirmatory trial to evaluate cadonilimab plus chemotherapy as 1L treatment for R/M cervical cancer is ongoing.

Transcriptomic Correlates of Tumor Cell PD-L1 Expression and Response to Nivolumab Monotherapy in Metastatic Clear Cell Renal Cell Carcinoma.

PD-L1 expression on tumor cells (TC) is associated with response to anti-PD-1-based therapies in some tumor types, but its significance in clear cell renal cell carcinoma (ccRCC) is uncertain. We leveraged tumor heterogeneity to identify molecular correlates of TC PD-L1 expression in ccRCC and assessed their role in predicting response to anti-PD-1 monotherapy. RNA sequencing was performed on paired TC PD-L1 positive and negative areas isolated from eight ccRCC tumors and transcriptomic features associated with PD-L1 status were identified. A cohort of 232 patients with metastatic ccRCC from the randomized CheckMate-025 (CM-025) trial was used to confirm the findings and correlate transcriptomic profiles with clinical outcomes. In both the paired samples and the CM-025 cohort, TC PD-L1 expression was associated with combined overexpression of immune- and cell proliferation-related pathways, upregulation of T-cell activation signatures, and increased tumor-infiltrating immune cells. In the CM-025 cohort, TC PD-L1 expression was not associated with clinical outcomes. A molecular RCC subtype characterized by combined overexpression of immune- and cell proliferation-related pathways (previously defined by unsupervised clustering of transcriptomic data) was enriched in TC PD-L1 positive tumors and displayed longer progression-free survival (HR, 0.32; 95% confidence interval, 0.13-0.83) and higher objective response rate (30% vs. 0%, P = 0.04) on nivolumab compared with everolimus. Both TC-extrinsic (immune-related) and TC-intrinsic (cell proliferation-related) mechanisms are likely intertwined in the regulation of TC PD-L1 expression in ccRCC. The quantitation of these transcriptional programs may better predict benefit from anti-PD-1-based therapy compared with TC PD-L1 expression alone in ccRCC.

Vγ2 x PD-L1, a Bispecific Antibody Targeting Both the Vγ2 TCR and PD-L1, Improves the Anti-Tumor Response of Vγ2Vδ2 T Cell.

The potent cytotoxic property of Vγ2Vδ2 T cells makes them attractive for adoptive T cell transfer therapy. The transfusing of the expanded Vγ2Vδ2 T cells into cancer patients shows well-tolerated, but the clinical response rates are required to be improved, implying that there is still an unmet efficacy with low toxicity for this novel anti-tumor therapy. In this study, we test the anti-tumor efficacy of a Y-body-based bispecific antibody (bsAb) Vγ2 x PD-L1 that preferentially redirects Vγ2Vδ2 T cells to combat PD-L1 positive tumor cells. With nanomolar affinity levels to Vγ2Vδ2 T cells and PD-L1+ tumor cells, Vγ2 x PD-L1 bridges a Vγ2Vδ2 T cell with a SKOV3 tumor cell to form a cell-to-cell conjugation. In a PD-L1-dependent manner, the bsAb elicits effective activation (CD25+CD69+), IFNγ releasing, degranulation (CD107a+), and cytokine production (IFNγ+ and TNFα+) of expanded Vγ2Vδ2 T cells. The activations of the Vγ2Vδ2 T cells eliminate PD-L1-expressing human cancer cell lines, including H1975, SKOV3, A375, H1299, and H2228 cells, but not PD-L1 negative cells including HEK-293 (293) cells and healthy PBMCs. Finally, we show that combining Vγ2 x PD-L1 with adoptively transferring Vγ2Vδ2 T cells inhibits the growth of existing tumor xenografts and increases the number of Vγ2Vδ2 T cells into the tumor bed. Vγ2 x PD-L1 represents a promising reagent for increasing the efficacy of adoptively transferred Vγ2Vδ2 T cells in the treatment of PD-L1 positive malignant tumors.

Abstract 6100: Chemotherapy reduces TGF-beta signaling triggered by blockade of the PD-1/PD-L1 axis

Abstract Combination of immune checkpoint blockade (ICB) with chemotherapy is becoming more commonly used for the treatment of various cancer types, including advanced non-small cell lung cancer, and triple negative breast cancer (TNBC) in patients who have PD-L1 positive tumors, among others. Although chemotherapy-ICB modalities have been shown to improve clinical responses over those observed with ICB alone, long-term disease control is achieved only in a small subset of patients. To provide a rational basis for combination therapy, and to potentially develop more effective approaches, in this study we investigated the impact of chemotherapy on the tumor microenvironment (TME) in the context of PD-1/PD-L1 axis blockade. ICB refractory murine models were utilized, including the TNBC 4T1 model and the Lewis Lung Carcinoma (LLC) model. Following treatments with anti-PD-L1, docetaxel, or the combination anti-PD-L1 plus docetaxel, tumors were collected 4 days after the last treatment to evaluate early changes in the TME. Analyses included the characterization of tumor immune infiltrates via flow cytometry, RNA expression profiling via RT-PCR, RNA in situ hybridization, and immunohistochemistry for detection of immune infiltrates, cancer-associated fibroblasts, and phospho-Smad2 signaling. RNA analysis of 4T1 and LLC tumors revealed a significant upregulation of several transforming growth factor-beta (TGF-beta) downstream target genes in the anti-PD-L1 monotherapy group. This increase was associated with enhanced expression of TGF-beta in the TME, as determined by RNA in situ hybridization, together with enhanced TGF-beta signaling denoted by increased expression of phospho-Smad2. Tumors treated with anti-PD-L1 monotherapy also exhibited increased numbers of alpha-smooth muscle actin positive fibroblasts in the TME. The effects observed with anti-PD-L1 as a monotherapy were not observed in tumors treated with docetaxel monotherapy or in those treated with the combination docetaxel plus anti-PD-L1 therapy, suggesting that upregulation of immunosuppressive TGF-beta signaling in the TME could be prevented by the addition of chemotherapy. Ongoing and future studies are aimed at understanding the mechanisms involved in the upregulation of TGF-beta signaling in the TME in response to anti-PD-L1 therapy in non-responsive tumors, the effect of various chemotherapies in this phenomenon, and the study of additional tumor models for optimization of chemotherapy-ICB modalities. Citation Format: Masafumi Iida, Lucas A Horn, Haiyan Qin, Kristen Fousek, Jeffrey Schlom, Claudia Palena. Chemotherapy reduces TGF-beta signaling triggered by blockade of the PD-1/PD-L1 axis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6100.

Abstract 335: c-KIT targeted ETBs for cancer therapy and HSC transplant conditioning

Abstract Engineered toxin bodies (ETBs) are next-generation immunotoxins that harbor an antibody-derived targeting domain and a cytotoxic payload derived from Shiga-like toxin-1 catalytic subunit A (SLTA). SLTA has been engineered to reduce innate immunogenicity and therefore increase the safety of ETBs whilst retaining potent cytotoxic properties. When targeted via a binding domain, SLTA is internalized and routes to the cytosol leading to irreversible ribosome inactivation and ultimately cell death. ETBs have been developed to treat a wide variety of cancers, including breast, lymphoma, multiple myeloma and PD-L1 positive solid tumors. This technology holds promise for non-oncology indications as well, particularly as a targeted and non-genotoxic conditioning regimen for hematopoietic stem cell (HSC) ablation to prepare patients for autologous stem cell transplant. c-KIT (CD117) is a well-known marker of hematopoietic stem and progenitor cells and is overexpressed in a high percentage of certain cancers including GIST, SCLC and AML. While tyrosine kinase inhibitors such as imatinib are effective therapies for c-KIT mutant GIST, resistance often occurs by the development of secondary mutations in the intracellular signaling domains. Thus, c-KIT represents a potential ETB target for both oncological and HSC transplant conditioning indications. Here we present data highlighting the in vitro potency and efficacy of CD117-targeting ETBs on cancer cell lines as well as on primary human CD34+ HSCs. CD117-targeted ETBs demonstrate exquisite specificity in vitro by killing only target positive CD34+ cells at picomolar potency while sparing the progenitors that lack CD117 expression. However, relatively low CD117 receptor levels on CD34+ HSCs prevent complete killing in vitro, limiting the observed efficacy. To overcome this challenge, an additional cytotoxic payload was conjugated to the ETB molecule to capitalize on ETBs’ unique internalization and routing properties to deliver a secondary mechanism of action. ETB-drug conjugates (ETB-DCs) exhibited improved cytotoxicity in vitro, especially in CD117-low target cells. Moving forward, we plan to explore both the ETB and the ETB-DC therapeutic index in vivo with a series of CD117+ tumor efficacy and HSC depletion models. Citation Format: Caleigh Howard, Shu Wiley, Wenzhao Dong, Andrea Mendiola, Veronica Partridge, Sara LeMar, Paul Amador, Amit K. Chaudhary, Joseph D. Dekker, Jay Zhao, Ross Durland, Aimee Iberg. c-KIT targeted ETBs for cancer therapy and HSC transplant conditioning [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 335.

Abstract 6152: Distinct immune gene programs associated with host tumor immunity, neoadjuvant chemotherapy and chemoimmunotherapy in resectable NSCLC

Abstract Background: Our understanding of the immunopathology of early-stage NSCLC is still limited. While neoadjuvant immunotherapeutic strategies have recently shown anti-tumor effects in resectable NSCLC, their mechanisms remain inadequately understood. Here, we explore immune programs that inform of tumor immunity and response to neoadjuvant chemotherapy and chemoimmunotherapy in localized NSCLC. Methods: Targeted immune gene sequencing using the HTG Precision Immuno-Oncology panel was performed in localized NSCLCs from three cohorts based on treatment: naïve (n=190), neoadjuvant chemotherapy (n=38) and neoadjuvant chemoimmunotherapy (n=21). Three tumor immune microenvironment (TIME) phenotypes (inflamed, cold, excluded) were derived based on CD8+ T cell infiltration. Signatures of immune cell abundance and immune genes were statistically compared based on tumoral PD-L1 expression, immune phenotypes, associated with pathological response, and were cross-compared across the three cohorts. Results: PD-L1 positive tumors exhibited increased signature scores for various lymphoid and myeloid cell subsets (both, p&amp;lt;0.05). TIME phenotypes exhibited disparate frequencies by stage, PD-L1 expression, and mutational burden. Inflamed NSCLCs displayed overall significantly heightened levels of immune signatures with the excluded group representing an intermediate state. A signature of cytotoxic T cells was associated with favorable survival in neoadjuvant chemotherapy-treated NSCLCs (p&amp;lt;0.05). Major pathological response to chemoimmunotherapy was positively associated with CD8 T cells (p&amp;lt;0.05) and Th1 cells were significantly reduced post-chemoimmunotherapy (p&amp;lt;0.001). Among the three cohorts, chemoimmunotherapy-treated NSCLCs exhibited highest scores for various immune cell subsets including T effector and B cells (both, p&amp;lt;0.05). Conclusions: Our findings highlight immune gene programs that may underlie host tumor immunity and response to neoadjuvant chemotherapy and chemoimmunotherapy in early-stage NSCLC. Citation Format: Pedro Rocha, Jiexin Zhang, Raquel Laza-Briviesca, Alberto Cruz-Bermúdez, Katsuhiro Yoshimura, Carmen Behrens, Apar Pataer, Edwin Parra-Cuentas, Cara Haymaker, Junya Fujimoto, Stephen Swisher, John Heymach, Don L. Gibbons, J Jack Lee, Boris Sepesi, Tina Cascone, Luisa M. Solis, Mariano Provencio, Ignacio I. Wistuba, Humam Kadara. Distinct immune gene programs associated with host tumor immunity, neoadjuvant chemotherapy and chemoimmunotherapy in resectable NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6152.

Abstract LB214: Discovery of EPIM-001, a tumor targeted engineered IL2 with biased IL2Rβ agonist activities

Abstract Background: The cytokine Interleukin 2 (IL2) has been approved for cancer treatment. However, its application has been limited due to severe toxicities associated with its high concentration administration. These side effects are attributed to the strong binding of IL2 to its receptor IL2Rα which is enriched on regulatory T Cells and Lung epithelial cells. We have engineered IL2 to significantly reduce IL2Rα binding and enhance IL2Rβ binding. We further developed EPIM-001, a bi-functional IL2Rβ agonist and Anti-PDL1 biologic, aiming to treat a broad set of solid tumors with improved therapeutic index. Methods: We used mSCAFold࣪, a unique protein engineering platform to redefine and improve pharmacologic properties of the cytokine through structure-based rationally designed libraries and mRNA display selection. The optimal IL2 candidate with enhanced IL2Rβ and reduced IL2Rα binding was engineered with an internally discovered anti-PD-L1 antibody to generate EPIM-001, a bispecific IL2/PD-L1 biologic drug candidate. EPIM-001 was characterized in vitro for receptor binding activity, immune cell activation, proliferation, and tumor cell killing assays. In vivo efficacy was evaluated in xenograft humanized mouse models, and PK/PD and toxicity has been studied in Non-Human Primates (NHPs). Results: We have shown that EPIM-001 is a strong agonist of IL2Rβ, with significantly reduced binding to IL2Rα. It demonstrated much stronger CD8+ T cells and NK cell activation and proliferation compared WT-IL2, whilst only weaker activation and minimal proliferation with Tregs. In vitro cell killing assays showed that EPIM-001 promoted better immune cell killing of PD-L1 expressing target cells than WT IL2. In xenograft in vivo studies, EPIM-001 has shown significant tumor growth inhibition against the human lung cancer cell line H1975, which whilst expressing high levels of PD-L1, does not respond to PD-L1/PD-1 blockade. Furthermore, in the human breast cancer cell line MDA-MB-231, EPIM-001 showed stronger tumor growth inhibition compared to Keytruda. PK/PD and toxicity studies in NHPs showed that EPIM-001 is well tolerated. EPIM-001 greatly expanded CD8+ T cells, whilst having minimal effect on TRegs and Eosinophils associated with toxicity. Conclusions: EPIM-001 is a promising immune modulating drug candidate that selectively activates CD8+ T cells and NK Cells with strong anti-tumor activity and safe profile for both immune checkpoint sensitive and insensitive PD-L1 positive tumors. Citation Format: Kehao Zhao, Sam Hassan, Yan Chen, Jenna Nguyen, Ning Jiang, Gening Zhang, Irene Li, Ryan Feng. Discovery of EPIM-001, a tumor targeted engineered IL2 with biased IL2Rβ agonist activities [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB214.

Comprehensive immune profiling unravels evolution of spatial distribution and immune repertoire in tumor microenvironment from primary to metastatic triple-negative breast cancer.

1079 Background: Immune checkpoint inhibitors (ICI) have improved PFS and OS in metastatic triple-negative breast cancer (mTNBC), but benefit is limited to PD-L1 positive tumors. Metastatic tumors are notorious for deficient immune cell infiltration and immunosuppressive features that may limit responses to ICI in mTNBC. However, the underlying mechanisms for the weak immunogenicity of the metastatic tumor immune microenvironment (TIME) and related poor ICI responses are still not well understood. The current study was designed to investigate the evolution of the TIME between paired primary and metastatic TNBCs. Methods: Spatial distribution of 37 key immune regulators using the NanoString digital spatial profiling (DSP) platform was analyzed. 452 regions of interests (ROIs) from 33 primary tumors (PT) and 29 metastatic tumors (MT) including 28 paired specimens, were selected based on CD45+ immune hotspots, and the protein expression levels of the key immune regulators were quantified within pan-cytokeratin (panCK) and CD45 masked regions, respectively. In parallel, we examined the clonality of tumor infiltrating B cell receptors by reconstructing the immune repertoire from bulk RNA-seq data. Results: Using the DSP platform, we confirmed reduced immune infiltration (e.g., CD3 and CD20) in both panCK and CD45 masked regions of MT, while CD8A and CD11c (padj = 2.8×10-7 and 2.1×10-6) expression was only observed in panCK masked regions of MT compared with PT. A significant shift in myeloid composition between PT and MT as evidenced by increased CD68 signal (padj = 5.8×10-4) in CD45 masked regions of MT was identified. Within MT, PD-L1 signal was substantially higher (padj = 0.030) in CD45 masked regions only, while PD1 counts were lower (padj = 0.035) in panCK masked regions. This suggests the limited responses to ICI for MT may stem from relatively low expression of activated and targetable T cell subsets in MT islands. In support of the lower CD20 counts in MT, immune repertoire analysis revealed B cell receptor (BCR) repertoire diversity (represented by Gini index) was substantially lower in MT than PT (p = 0.041) suggesting that the ability of B cells to recognize a wide variety of tumor antigens in MT is greatly reduced in contrast to PT. Conclusions: Through comprehensive analysis of the TIME spatial organization within paired PT and MT, a significant reduction in dendritic cell/macrophage ratios (CD11c/CD68), reduced tumor localized T cell activation (CD8, PD1, PD-L1), and reduced B cell diversity (BCR clonality) are key features of the reduced immunogenicity of the metastatic TIME in TNBC. Further work to understand key mechanistic features driving the evolution of these differences in TIME between primary and metastatic tumors are ongoing.

EA2183: A phase III study of consolidative radiotherapy in patients with oligometastatic HER2-negative esophageal and gastric adenocarcinoma.

TPS4162 Background: Advanced esophageal and gastric adenocarcinomas (EGA) have poor prognosis. Doublet chemotherapy with fluoropyrimidine and platinum agents in combination with nivolumab for PD-L1 positive tumors is now the standard first-line approach, but overall survival (OS) remains &lt; 1.5 years. A subset of EGA patients have limited burden of metastatic disease. There is accumulating evidence that patients with oligometastatic states across disease types may benefit from locoregional ablative therapies during the course of their treatment. EA2183 is the first prospective study to evaluate the potential benefits of consolidative radiotherapy (XRT) in oligometastatic EGA. Methods: This is a prospective, randomized phase 3 study evaluating the role of consolidative XRT in oligometastatic EGA. Patients with ≤3 metastases at the time of diagnosis of advanced disease are eligible for enrollment. After completion of 4 months of systemic therapy, patients whose disease has not progressed are randomized to consolidation with XRT to all sites of disease followed by continuation of systemic therapy or continuation of systemic therapy alone. Patients are able to enroll in the study at the time of diagnosis of advanced disease or after completion of induction therapy. Systemic therapy is left to the discretion of the treating physician and can include FOLFOX (5-fluorouracil, leucovorin, and oxaliplatin) or CAPOX (capecitabine, oxaliplatin) in combination with nivolumab. Unless there are contraindications to immunotherapy or a history of prior treatment with immune checkpoint inhibitors, nivolumab use is mandatory if tumor has PD-L1 combined positive score (CPS) ≥5. The goal of radiation is to consolidate gains made by chemotherapy by delivering the highest dose that maintains the greatest tumor control probability that is also safe to deliver given the anatomic and normal tissue constraints. Specific radiation dose and fractionation are recommended in the protocol but is left to the discretion of the treating radiation oncologist to choose the course that is most suitable. Radiation must be administered over a maximum of 15 treatment days to minimize systemic therapy treatment breaks. Primary endpoint is OS from the time of randomization. Secondary endpoints include progression free survival from the time of randomization and safety and tolerability of consolidative XRT. We hypothesize that consolidative XRT will prolong OS from 10 to 15.6 months (an increase in median OS of 55.6%). The study is planning to enroll 314 patients with the goal of randomizing 204 patients in a 2:1 fashion. Stratification factors include number of metastatic sites, choice of immunotherapy with relation to PD-L1 CPS, as well as time of registration to the protocol (before or after systemic therapy initiation). Enrollment to the study is ongoing. Clinical trial information: NCT04248452.