Immune Checkpoint Inhibitors Targeting Research Articles

P08.02 Harnessing T cells to target brain metastasis

Abstract BACKGROUND Up to 60% of melanoma patients develop brain metastases (BrM). These patients have a poor prognosis and limited treatment options. Immune checkpoint inhibitors (ICI) targeting Cytotoxic T-lymphocyte-associated protein-4 (CTLA-4) and Programmed cell death protein-1 (PD-1) have revolutionized the treatment of melanoma and their efficacy has been also demonstrated in melanoma BrM. Our group previously demonstrated that ICI (combined α-PD-1 and α-CTLA-4) enhances chemokine-dependent infiltration of cytotoxic T lymphocytes (CTLs) into melanoma BrMs in preclinical models, accompanied by upregulated expression of T cell attracting chemokines in tumours. Notably, CTLs infiltrating BrM expressed only some of the chemokine receptors (CRs) interacting with ICI-induced chemokines in BrM, providing a rationale to over-express the “missing” CRs in T cells to enhance their homing to tumours in the context of adoptive T cell therapy (ACT). MATERIALS AND METHODS OT-I cells were isolated from OT-I mice and differentiated ex vivo into effector (TEF) and memory (TCM) CD8+ T cells. Tumour infiltrating lymphocytes (TILs) from B16 tumour-bearing mice treated with ICI were isolated using magnetic beads, activated and expanded ex vivo. Expression of CRs and activation markers in ex vivo cultured T cells were quantified by qPCR and/or flow cytometry. The migration of human blood CD8+ T cells towards chemokines of interest were measured in ex vivo migration assays. RESULTS The same CRs that were missing on BrM-infiltrating CTLs in vivo models were also absent from OT-I TEF (CCR7low/CD44high/CD62Llow) and TCM (CCR7high/CD44low/CD62Lhigh) cells, as well as from TILs expanded ex vivo for use in ACT. Furthermore, we observed no increase in migration of human T cells towards chemokines interacting with the “missing” CRs in comparison to the baseline migration, suggesting that these CRs are also absent from human T cells. CONCLUSION Ex vivo expanded T cells that are used in ACT are missing several CRs that are interacting with chemokines upregulated in BrM. We hypothesise that the use of genetically engineered T cells expressing the “missing” CRs in ACT has the potential to enhance ACT efficacy in combination with ICI.

1279P The prognostic value of chemotherapy-induced neutropenia (CIN) in patients with advanced non-small cell lung cancer (NSCLC) in the era of chemoimmunotherapy (CIT)

CIN was shown to be associated with a small but significant survival benefit in advanced NSCLC patients treated with chemotherapy. Since neutrophils are a form of myeloid-derived suppressor cells, which negatively regulate the function of T effector cells currently perceived as the major target of immune checkpoint inhibitors, we hypothesized that even a single episode of neutropenia may trigger a long-lasting immune response and lead to extended overall survival (OS) benefits.

CTLA-4 Synergizes With PD1/PD-L1 in the Inhibitory Tumor Microenvironment of Intrahepatic Cholangiocarcinoma.

Intrahepatic cholangiocarcinoma (ICC) is highly invasive and carries high mortality due to limited therapeutic strategies. In other solid tumors, immune checkpoint inhibitors (ICIs) target cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) and programmed death 1 (PD1), and the PD1 ligand PD-L1 has revolutionized treatment and improved outcomes. However, the relationship and clinical significance of CTLA-4 and PD-L1 expression in ICC remains to be addressed. Deciphering CTLA-4 and PD-L1 interactions in ICC enable targeted therapy for this disease. In this study, immunohistochemistry (IHC) was used to detect and quantify CTLA-4, forkhead box protein P3 (FOXP3), and PD-L1 in samples from 290 patients with ICC. The prognostic capabilities of CTLA-4, FOXP3, and PD-L1 expression in ICC were investigated with the Kaplan–Meier method. Independent risk factors related to ICC survival and recurrence were assessed by the Cox proportional hazards models. Here, we identified that CTLA-4+ lymphocyte density was elevated in ICC tumors compared with peritumoral hepatic tissues (P <.001), and patients with a high density of CTLA-4+ tumor-infiltrating lymphocytes (TILsCTLA-4 High) showed a reduced overall survival (OS) rate and increased cumulative recurrence rate compared with patients with TILsCTLA-4 Low (P <.001 and P = .024, respectively). Similarly, patients with high FOXP3+ TILs (TILsFOXP3 High) had poorer prognoses than patients with low FOXP3+ TILs (P = .021, P = .034, respectively), and the density of CTLA-4+ TILs was positively correlated with FOXP3+ TILs (Pearson r = .31, P <.001). Furthermore, patients with high PD-L1 expression in tumors (TumorPD-L1 High) and/or TILsCTLA-4 High presented worse OS and a higher recurrence rate than patients with TILsCTLA-4 LowTumorPD-L1 Low. Moreover, multiple tumors, lymph node metastasis, and high TumorPD-L1/TILsCTLA-4 were independent risk factors of cumulative recurrence and OS for patients after ICC tumor resection. Furthermore, among ICC patients, those with hepatolithiasis had a higher expression of CTLA-4 and worse OS compared with patients with HBV infection or undefined risk factors (P = .018). In conclusion, CTLA-4 is increased in TILs in ICC and has an expression profile distinct from PD1/PD-L1. TumorPD-L1/TILsCTLA-4 is a predictive factor of OS and ICC recurrence, suggesting that combined therapy targeting PD1/PD-L1 and CTLA-4 may be useful in treating patients with ICC.

Engineered extracellular vesicles for concurrent Anti-PDL1 immunotherapy and chemotherapy

Immune checkpoint inhibitors (ICI) targeting PD-1/PD-L1 have been approved for the treatment of a variety of cancers. However, the efficacy of antibody-based ICIs could be further improved by mitigating anti-drug antibodies, proteolytic cleavage, and on-target off-tumor toxicity. One strategy for accomplishing this is through the use of extracellular vesicles (EVs), cell derived submicron vesicles with many unique properties. We constructed an engineered MDA-MB-231 cell line for harvesting EVs. This was accomplished by overexpressing a high-affinity variant human PD-1 protein (havPD-1), while simultaneously knocking out intrinsic PD-L1 and beta-2 microglobulin. The engineered havPD-1 EVs reduced PD-L1 overexpressing cancer cell proliferation and induced cellular apoptosis. Moreover, the EVs were shown to efficiently block PD-L1 mediated T cell suppression. Meanwhile antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity were not observed. The havPD-1 EVs treatment resulted in robust anti-tumor activity in both preventative co-implantation and therapeutic xenograft tumor models reconstituted with human T cells. The efficacy of the havPD-1 EVs was shown to be comparable to clinical anti-PD1 monoclonal antibodies. Additionally, loading the havPD-1 EVs with a potent PARP inhibitor was shown to further augment treatment efficacy. In brief, the engineered universal EVs harboring havPD-1 proteins can be used for cancer concurrent immunotherapy and chemotherapy.

Molecular Pathology and Targeted Therapies for Personalized Management of Central Nervous System Germinoma.

Intracranial germinomas are rare tumours, usually affecting male paediatric patients. They frequently develop in the pineal and suprasellar regions, causing endocrinological disturbances, visual deficits, and increased intracranial pressure. The diagnosis is established on magnetic resonance imaging (MRI), serum and cerebrospinal fluid (CSF) markers, and tumour stereotactic biopsy. Imaging techniques, such as susceptibility-weighted imaging (SWI), T2* (T2-star) gradient echo (GRE) or arterial spin labelling based perfusion-weighted MRI (ASL-PWI) facilitate the diagnosis. Germinomas are highly radiosensitive tumours, with survival rates >90% in the context of chemoradiotherapy. However, patients with resistant disease have limited therapeutic options and poor survival. The aim of this review is to highlight the genetic, epigenetic, and immunologic features, which could provide the basis for targeted therapy. Intracranial germinomas present genetic and epigenetic alterations (chromosomal aberrations, KIT, MAPK and PI3K pathways mutations, DNA hypomethylation, miRNA dysregulation) that may represent targets for therapy. Tyrosine kinase and mTOR inhibitors warrant further investigation in these cases. Immune markers, PD-1 (programmed cell death protein 1) and PD-L1 (programmed death-ligand 1), are expressed in germinomas, representing potential targets for immune checkpoint inhibitors. Resistant cases should benefit from a personalized management: genetic and immunological testing and enrolment in trials evaluating targeted therapies in intracranial germinomas.

Abstract 29: The recently approved high-TMB criteria may introduce a sex bias in response to PD1 inhibitors

Abstract Motivation and research question: The U.S. Food and Drug Administration recently approved treatment with pembrolizumab, an immune checkpoint inhibitor (ICI) targeting PD1 (anti-PD1), for all advanced solid tumors with high tumor mutational burden (TMB), defined as ≥10 mutations/Megabase (mut/Mb). Recent studies have suggested that strength of immune selection, biomarkers of outcome, TMB levels and response to ICI treatment may differ between male and female cancer patients in some tumor types. This motivated us to examine what are the sex-specific implications, if any, of the ≥10 mut/Mb threshold on selecting patients for ICI treatment. Data &amp; Methods: We analyzed the largest ICI cohort publicly available to date (Samstein et al. 2019), including 1,070 patients treated with anti-PD1/PD-L1 monotherapy, 99 treated with anti-CTLA4 and 255 treated with an ICI combination. We focused on the nine solid tumor types with TMB and clinical response data (median follow-up of 19 months) for at least 50 patients. Results: 1.We observed a significant difference in the median TMB across sex among melanoma patients (n=130, female vs male median TMB=8.36 vs 11.81, P&amp;lt;0.02), in concordance with previous observations.2.Notably, we found that the FDA-approved threshold of ≥10 mut/Mb to select patients would result in an unwarranted sex bias in melanoma patients. This threshold successfully identifies female melanoma patients with better overall survival (hazard ratio (HR) =0.19, P&amp;lt;0.03) but fails to do so in male patients (HR=0.94, P&amp;lt;0.85), resulting in a five times higher HR in males vs females at that threshold level (interaction between sex and TMB P&amp;lt;0.03). This bias in effect size by sex is confirmed in two additional melanoma cohorts treated with anti-PD1 (Hugo et al. 2016, N=38, P&amp;lt;0.024; Liu et al. 2016, N=114, P&amp;lt;0.03; and P&amp;lt;0.01 for all three melanoma datasets combined, N=312). We do not observe this differential effect for anti-CTLA4 treatment (P&amp;lt;0.14, N=174) or for anti-PD1 + anti-CTLA4 combination (P&amp;lt;0.8, N=115) or for non-ICI treatments (P&amp;lt;0.4, N=322).3.Analysis of additional eight cancer types whose data are available in (Samstein et al 2019) points to glioblastoma (female vs male HR=0.87 vs 0.5) and cancer of unknown origin (female vs male HR= 1.03 vs 0.15), which show marked differences in the HR between male and female patients when applying the FDA threshold for TMB. However, despite these large effects, they do not achieve statistical significance, probably due to the small size of these datasets. Conclusions: The FDA-approved criteria of 10 mutations/Mb could serve as an informative biomarker for stratifying female melanoma patients but is inadequate for stratifying male patients for anti-PD1 treatment. Our results indicate that its usage is likely to introduce a sex bias in additional cancer types, which will be highly important to carefully test further in larger datasets. Citation Format: Neelam Sinha, Sanju Sinha, Kuoyuan Cheng, Sanna Madan, Alejandro Schaffer, Kenneth Aldape, Ayelet Erez, Brid M. Ryan, Eytan Ruppin. The recently approved high-TMB criteria may introduce a sex bias in response to PD1 inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 29.

Abstract 1878: Fc-enhanced anti-CTLA-4 antibody, AGEN1181: new mechanistic insights for potent antitumor immunity and combination potential in treatment-resistant solid tumors

Abstract The advent of immune checkpoint inhibitors (ICI) targeting cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), programmed cell death protein 1 (PD-1), or programmed death-ligand 1 (PD-L1) transformed the treatment landscape in a variety of human cancers. However, responses to currently approved ICI agents occur in small subsets of patients with immunogenic tumors, and resistance to ICI therapy continues to be a limiting factor to achieving optimal clinical benefits. AGEN1181 is a Fc-enhanced, clinical-stage anti-CTLA-4 antibody designed to expand therapeutic benefit to a broader patient population, including tumor types that are refractory to conventional ICI approaches. Here we show that AGEN1181 exploits a novel Fcy receptor-related mechanism of action to promote T cell-mediated antitumor immunity. In primary in vitro T cell and antigen presenting cell (APC) co-culture stimulation assays, AGEN1181 demonstrated superior T cell priming and activation that was independent of Treg depletion, and across all CD16 allele variants - in contrast to conventional IgG1 agents that showed limited activity. In PD-1 refractory tumor-bearing mouse models, a murine AGEN1181 surrogate demonstrated superior antitumor activity compared to an Fc-unmodified anti-CTLA-4 antibody. This enhanced activity was associated with improved T cell priming, intratumoral Treg depletion, increased frequency of CD8 effector memory precursor T cells, enhanced peripheral TCR clonality, and expansion of tumor-associated T cell clones. Next we evaluated the combination potential of the AGEN1181 surrogate with targeted therapies, cell therapy or checkpoint blockade in a series of treatment-resistant preclinical tumor models. Notably, this antibody induced robust tumor control and antitumor immunity when administered alongside anti-PD-1 and focal radiation, adoptive T cell therapy, or iNKT-activating therapy in the refractory B16F10 or B16F1.OVA melanoma models. In treatment-resistant KPC pancreatic ductal tumor-bearing mice, curative responses were seen in combination with chemotherapy (gemcitabine, nab-paclitaxel and cisplatin). Moreover, combinations with other ICI (e.g. anti-PD-1 or anti-TIGIT antibodies) deepened responsiveness and overcame limited activity seen with conventional ICI therapy. Importantly, antitumor immune responses could be further improved with optimal sequencing of combination therapies with AGEN1181. Together, these data demonstrate that the novel Fcy receptor-related mechanism of action employed by AGEN1181 enhances antitumor immunity and confers the potential to expand therapeutic benefit to tumors refractory to ICI therapy. Clinical responses support these findings and a phase II trial is underway in patients with a range of solid tumor types, including angiosarcoma and microsatellite stable tumors. Citation Format: Antoine J. Tanne, Claire Galand, Abdo Abou-Slaybi, Margaret Wilkens, Marilyn Marques, Serina Ng, Haiyong Han, Sylvia Dietrich, Jeremy Waight, Bishnu Joshi, Burcu Yigit, Xavier Michelet, Daniel Levey, David Savitsky, Jennifer Buell, Dhan Chand. Fc-enhanced anti-CTLA-4 antibody, AGEN1181: new mechanistic insights for potent antitumor immunity and combination potential in treatment-resistant solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1878.

Abstract 1853: A novel anti-CTLA-4 checkpoint inhibitor prodrug to address on-target off-tumor toxicity for cancer immunotherapy

Abstract As the first approved immune checkpoint inhibitor targeting CTLA-4, ipilimumab has achieved great clinical success in cancer immunotherapy, particularly in combination with anti-PD-1 therapy. However, ipilimumab can also induce severe and sometimes fatal immune-mediated adverse reactions due to autoimmune responses in normal tissues, which may involve any organ system and cause enterocolitis, hepatitis, dermatologic adverse effects, endocrinopathies, pneumonitis, and nephritis with renal dysfunction, restricting its clinical applications. Thus, development of next generation anti-CTLA-4 antibodies with enhanced antitumor efficacy and improved safety profile is urgently needed. ADG126 is a novel anti-CTLA-4 fully human IgG1 antibody prodrug generated with Adagene SAFEbody technology, which is designed to be activated preferentially in the tumor microenvironment, limiting on-target off-tumor toxicities in normal tissues. This is realized by attaching an optimized peptide through library screening to the N-terminus of the light chain consisting of a masking moiety followed by a cleavage moiety. The masking moiety functions to block ADG126 binding to CTLA-4, however, after cleavage by proteases known to be highly expressed and active in tumor tissues but not in normal tissues, the masking moiety is released, and the antibody is then activated and able to bind and inhibit CTLA-4 function in situ, which has the potential to minimize the side effects and widen the therapeutic window compared to traditional antibodies. Nonclinical pharmacological studies demonstrate that unmasked or activated ADG126 (but not masked or inactive ADG126) binds to a unique and conserved epitope of CTLA-4 with multiple species cross-reactivity and effectively blocks the CTLA-4/B7 ligands interactions. Activated ADG126 potentiates T cell activation inducing elevated IL-2 cytokine production in the presence of a primary stimulatory signal, depletes immunosuppressive Treg activity through enhanced ADCC, and reduces immunosuppressive Treg activity specifically in the tumor microenvironment to mediate anti-tumor responses. ADG126 demonstrates efficacious anti-tumor activity in multiple syngeneic murine tumor models as single agent, as well as in combination with other immune modulatory agents. Nonclinical toxicology studies demonstrate that ADG126 is well-tolerated in cynomolgus monkeys. These results suggest that the design to have activation of ADG126 prodrug preferentially in tumors may allow treatments to deliver higher efficacious dose levels specific to the local tumor microenvironment concomitant with a superior systemic safety profile compared with other traditional anti-CTLA-4 antibodies. Thus, ADG126 may hold great promises to achieve much better efficacy and safety profile for immunotherapy against a broad spectrum of human cancers. Citation Format: Guizhong Liu, Xiaohong She, Yan Li, Felix Du, Peter Luo. A novel anti-CTLA-4 checkpoint inhibitor prodrug to address on-target off-tumor toxicity for cancer immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1853.

Renal Complications Related to Checkpoint Inhibitors: Diagnostic and Therapeutic Strategies.

Immune checkpoint inhibitors (ICI) targeting CTLA-4 and the PD-1/PD-L1 axis have unprecedentedly improved global prognosis in several types of cancers. However, they are associated with the occurrence of immune-related adverse events. Despite their low incidence, renal complications can interfere with the oncologic strategy. The breaking of peripheral tolerance and the emergence of auto- or drug-reactive T-cells are the main pathophysiological hypotheses to explain renal complications after ICI exposure. ICIs can induce a large spectrum of renal symptoms with variable severity (from isolated electrolyte disorders to dialysis-dependent acute kidney injury (AKI)) and presentation (acute tubule-interstitial nephritis in >90% of cases and a minority of glomerular diseases). In this review, the current trends in diagnosis and treatment strategies are summarized. The diagnosis of ICI-related renal complications requires special steps to avoid confounding factors, identify known risk factors (lower baseline estimated glomerular filtration rate, proton pump inhibitor use, and combination ICI therapy), and prove ICI causality, even after long-term exposure (weeks to months). A kidney biopsy should be performed as soon as possible. The treatment strategies rely on ICI discontinuation as well as co-medications, corticosteroids for 2 months, and tailored immunosuppressive drugs when renal response is not achieved.

The dark side of immunotherapy.

Immunotherapy has broadened the therapeutic scope and response for many cancer patients with drugs that are generally of higher efficacy and less toxicity than prior therapies. Multiple classes of immunotherapies such as targeted antibodies and immune checkpoint inhibitors (ICI), cell-based immunotherapies, immunomodulators, vaccines, and oncolytic viruses have been developed to help the immune system target and destroy malignant tumors. ICI targeting programmed cell death protein-1 (PD-1) or its ligand (PD-L1) are among the most effective immunotherapy agents and are a major focus of current investigations. They have received approval for at least 16 different tumor types as well as for unresectable or metastatic tumors with microsatellite instability-high (MSI-H) or mismatch repair deficiency or with high tumor mutational burden (defined as ≥10 mutations/megabase). However, it is important to recognize that immunotherapy may be associated with significant adverse events. To summarize these events, we conducted a PubMed and Google Scholar database search through April 2020 for manuscripts evaluating treatment-related adverse events and knowledge gaps associated with the use of immunotherapy. Reviewed topics include immune-related adverse events (irAEs), toxicities on combining immunotherapy with other agents, disease reactivation such as tuberculosis (TB) and sarcoid-like granulomatosis, tumor hyperprogression (HPD), financial toxicity, challenges in special patient populations such as solid organ transplant recipients and those with auto-immune diseases. We also reviewed reports of worse or even lethal outcomes compared to other oncologic therapies in certain scenarios and summarized biomarkers predicting adverse events.

Impact of cancer type on the incidence of cutaneous toxicities after immune checkpoint inhibitor therapy: A population-level analysis.

e14553 Background: Cutaneous immune-related adverse events (cirAEs) from immune checkpoint inhibitor (ICI) therapy are increasing as these drugs are more widely used. Population-level studies are lacking. In this retrospective cohort study, we analyzed the primary tumor’s effect on cirAE incidence and downstream utilization of systemic immunosuppression in a national healthcare database (TriNetX). Methods: Index event was defined as day of ICI initiation; outcomes were restricted to 2 years from index. cirAEs were defined as 42 dermatoses identified in a comprehensive review of the cirAE literature (Sibaud 2018) and expert opinion. Systemic immunosuppression was classified as steroidal or non-steroidal. Primary outcomes included aggregate and cancer-specific incidence of cirAEs across the four most common cancer indications for ICI therapy (melanoma, lung, urinary, and gastrointestinal). Secondary outcomes included utilization of new steroidal or non-steroidal systemic immunosuppression. For each analysis, we excluded patients with an outcome prior to the index event. Risk ratios (RR) were calculated after 1-to-1 propensity score matching, adjusting for age at index, sex, race, ethnicity, and ICI target, with the lung cancer group as reference. Results: We identified 27,481 eligible subjects. Aggregate incidence of cirAEs across all cancer types was 23.41%, with non-specific rashes, pruritus, and drug eruptions as the most common diagnoses. Among all patients, new steroidal and non-steroidal immunosuppression use following ICI initiation was 16.1% and 4.1%, respectively. After adjusting for covariates, melanoma (RR 1.60, 95% CI 1.43-1.79, p &lt; 0.001) was associated with a higher risk of cirAE, while urinary and gastrointestinal tract cancers were not significantly different from the reference. Melanoma (RR 0.64, 95% CI 0.55-0.74), urinary tract (RR 0.71, 95% CI 0.62-0.81) and gastrointestinal tract (RR 0.46, 95% CI 0.39-0.53) cancers were all less likely to require steroidal immunosuppression (all p &lt; 0.001). However, patients with urinary tract cancer (RR 4.03, 95% CI 3.04-5.35) and melanoma (RR 2.44, 95% CI 1.75-3.40) were more likely to receive non-steroidal systemic immunosuppression (both p &lt; 0.001). Conclusions: Our results reinforce that ICI recipients commonly develop skin toxicities and provide robust evidence that melanoma is independently associated with their incidence. Furthermore, we found that patients with lung cancers received steroidal systemic immunosuppression most frequently, an intervention associated with poorer overall survival (Riudavets 2020). In contrast, patients with melanoma were more likely to receive non-steroidal immunosuppression. This study is the first population-based analysis of an irAE across tumor types and is proof-of-concept for future investigations into clinical risk factors in a large dataset.

First-line therapy in patients with metastatic renal cell carcinoma (mRCC): Results from consecutive patients over 25 years in a single institution.

e16574 Background: Immune checkpoint inhibitors (ICI) have demonstrated improved activity in metastatic renal cell carcinoma (mRCC). Real-world data comparing the effectiveness of ICI with interleukin-2 (IL-2) is limited. Methods: We retrospectively assessed consecutive patients with biopsy-proven mRCC at our institution between 1994 and 2020. Patients were classified into four groups based on first-line therapy: vascular endothelial growth factor (VEGF) inhibitors, mammalian target of rapamycin (mTOR) inhibitors, IL-2, or ICI. The primary endpoint was overall survival (OS). Kaplan-Meier method was used to compare OS between treatment groups. We used Cox proportional hazards models to adjust for prognostic covariates. Results: A total of 1424 patients were treated with first line therapy; 51% received VEGF, 3% received mTOR, 40% received IL-2, and 6% received ICI. Median follow-up was 97.6 months. Except for the mTOR group, baseline characteristics were largely balanced between the treatment groups. Median OS in the ICI group compared with IL-2, mTOR and VEGF was 40.1, 17.6, 6.3 and 14.7 months (p &lt; 0.001), respectively, and the 5-year survival rate was 36%, 20%, 9% and 14%, respectively. After adjusting for IMDC and MSKCC individual risk factors, histology, age, gender, year of treatment initiation, low sodium, and location of metastases (lung, liver, bone, lymph node), the hazard ratio (HR) (95%CI) for OS with VEGF as reference was 0.50 (0.33-0.74, p = 0.001) for ICI, 0.81 (0.70-0.92, p = 0.002) for IL2, and 1.09 (0.79-1.52, p = 0.6) for mTOR. Conclusions: In this largest single institution cohort to date, patients with mRCC who received CPI achieved longer OS.[Table: see text]

Immune checkpoint inhibitor plus anti-EGFR target therapy plus chemotherapy in patients with locally advanced penile squamous cell carcinoma.

e17016 Background: Locally advanced penile squamous cell carcinomas (PSCCs) have poor prognosis and limited therapeutic options. We aim to evaluate the safety and the efficacy of neoadjuvant therapy with anti-PD-1 immune therapy (toripalimab) plus anti-EGFR target therapy (nimotuzumab) plus chemotherapy (TIP) in locally advanced PSCCs. Methods: We retrospectively reviewed chemotherapy-naive, unresectable locally advanced PSCCs (T4NanyM0 or TanyN3M0) who received combined neoadjuvant therapy and subsequently radical surgery in Sun Yat-sen University Cancer Center between 2018 and 2020. All patients received toripalimab 240mg on day 1 plus nimotuzumab 400mg on day 1 plus standard-of-care TIP (Cisplatin 25mg/m2 on day 1 to day 3; ifosfamide 1.2g/m2 on day 1 to day 3; paclitaxel 175mg/m2 or albumin-bound paclitaxel 260mg/m2 on day 1) every 3-4 weeks. Pathologic complete response(pCR) rate and toxicity were evaluated. Progression-free survival (PFS) and overall survival (OS) were calculated by Kaplan-Meier estimation. Results: We screened 12 patients in total who had performed toripalimab plus nimotuzumab plus TIP (TNTIP) as neoadjuvant treatment and subsequently radical surgery. Median age was 51 (95% confidence interval [CI]: 44-60.5) years old. 10(83.3%) patients received 3 or 4 courses of TNTIP neoadjuvant treatment. After neoadjuvant treatment and radical surgery, 8(66.7%) patients had a pCR. 2(16.7%) patients died of disease progress or recurrence, which 1(8.3%) patient occurred bone metastases after 2 courses of TNTIP, and 1(8.3%) patient appeared recurrence after 6 months of radical surgery. The median follow-up time was 21.3 months (95%CI 19.9-22.6). Median PFS and OS were not reached. The 1-year PFS rate was 83.3% and 1-year OS rate was 91.7%. 3(25%) patients experienced grade 3 treatment-related adverse events of fatigue, anemia and neutropenia. No grade 4 or 5 adverse events or death associated with treatment. Conclusions: Compared with other therapeutic options, our results suggest that TNTIP in neoadjuvant stage effectively improve the disease control and prognosis in locally advanced PSCCs. Based on this result, we are conducting a phase II study in Sun Yat-sen University Cancer Center to further validate the efficacy and safety of TNTIP neoadjuvant regimen in locally advanced PSCCs. (ClinicalTrials.gov No. NCT04475016).

Histopathology of Gastrointestinal Immune-related Adverse Events: A Practical Review for the Practicing Pathologist.

Immune checkpoint inhibitors target checkpoint proteins with the goal of reinvigorating the host immune system and thus restoring antitumor response. With the dramatic increase in the use of checkpoint inhibitors for cancer treatment, surgical pathologists have assumed a major role in predicting the therapeutic efficacy (score based on programmed cell death ligand 1 immunohistochemistry and mismatch repair protein loss) as well as diagnosing the complications associated with these medications. Immune-related adverse events (irAEs) manifest as histologic changes seen in both the upper and lower gastrointestinal tract, and when viewed in isolation, may be morphologically indistinguishable from a wide range of diseases including infections, celiac disease, and inflammatory bowel disease, among others. Evaluation of biopsies from both the upper and lower gastrointestinal tract can aid in the distinction of gastrointestinal irAEs from their mimics. In the liver, the histologic changes of hepatic irAEs overlap with de novo diseases associated with hepatitic and cholangitic patterns of injury. The diagnosis of irAEs requires communication and collaboration from the pathologist, oncologist, and gastroenterologist. This review provides a background framework and illustrates the histologic features and differential diagnosis of gastrointestinal and hepatic irAEs.

Genetic linkage analysis using Diversity Outbred mice identifies prolactin as a host-intrinsic regulator of immune checkpoint inhibitor response

Abstract The use of immune checkpoint inhibitors (ICI) targeting CTLA-4 and PD-1 have greatly improved patient survival in metastatic melanoma, but a significant proportion of patients fail to respond to therapy. Incorporating what has been learned in autoimmune conditions, we hypothesize the host genetic background plays a significant role in determining response to immunotherapy. To implement genetic diversity, Diversity Outbred (DO) mice were crossed with C57BL/6 to generate (C57BL/6xDO)F1 mice that reliably develop B16F0 tumors after subcutaneous inoculation. (C57BL/6xDO)F1 mice (n=142) treated with combined anti-PD1/anti-CTLA-4 on days 3, 6, and 10 after inoculation show wide variation in tumor latency up to a maximum of 65 days, with 19 mice never developing tumor. Genetic linkage analysis using the R/qtl2 package shows a suggestive association within the murine prolactin family on chromosome 13. Visualization of QTL effects by DO founder identifies the NZO mouse genotype as a driver of increased tumor latency. Validation was performed using Collaborative Cross (CC) mouse lines that were either the NZO or C57BL/6 genotype within this locus. (C57BL/6xCC)F1 mice containing the NZO genotype have lower tumor burden by day 15 compared to mice with the C57BL/6 genotype, validating the locus as influential on the response to ICI. Combination of systemic prolactin treatment and ICI shows evidence of an interaction effect. Mice treated with both prolactin and ICI show lower tumor burden by day 19 versus single therapy or placebo controls. These results show that the host’s genetic background significantly contributes to response to ICI, and modulation of prolactin expression may augment ICI activity.

Management of Hematologic Adverse Events Associated With Immune Checkpoint Inhibitors.

Immune checkpoint inhibitors target suppressor receptors, including cytotoxic T-lymphocyte–associated antigen 4 (CTLA-4), programmed cell death protein 1 (PD-1), and programmed cell death ligand 1 (PD-L1). The activated T cells are not antigen specific; therefore, the blockade of the immune checkpoint may result in the development of autoimmune adverse events. The most common immune-related adverse events (irAEs) are rash, colitis, and endocrinopathies. However, irAEs that affect the hematologic system are rare and can affect red blood cells (e.g., autoimmune hemolytic anemia), white blood cells, and platelets (e.g., immune thrombocytopenia). Usually one cell line is affected; however, in some cases, multiple cell lines can be affected. Other changes in the hematologic system can also be affected (e.g., cryoglobulinemia, cytokine release syndrome). Due to the rarity and lack of recognition of these AEs, the timing, spectrum of events, and clinical presentation are poorly understood. Management of hematologic irAEs usually involves the use of steroids; however, other agents (e.g., IVIG, cyclosporine, rituximab) or procedures (e.g., plasma exchange, transfusions) can also be used.

LAG-3 expression in the inflammatory microenvironment of glioma

PurposeImmune modulatory therapies including immune checkpoint inhibitors have so far failed to result in clinically meaningful efficacy in glioma. We aimed to investigate lymphocyte activation gene 3 (LAG-3), an inhibitory receptor on immune cells and target of second-generation immune checkpoint inhibitors, in glioma.Methods97 patients with diffuse glioma (68 with glioblastoma, 29 with WHO grade II-III glioma) were identified from the Neuro-Biobank of the Medical University of Vienna. LAG-3 expression in the inflammatory microenvironment was assessed by immunohistochemistry (monoclonal anti-LAG-3 antibody, clone 17B4) and correlated to CD3+ , CD8+ , CD20+ and PD-1+ tumor-infiltrating lymphocytes (TILs) and PD-L1 expression on tumor cells.ResultsLAG-3+ TILs could be observed in 10/97 (10.3%) IDH-wildtype samples and in none of the included IDH-mutant glioma samples (p = 0.057). Further, LAG-3+ TILs were only observed in WHO grade IV glioblastoma, while none of the investigated WHO grade II–III glioma presented with LAG-3+ TILs (p = 0.03). No association of O6-methylguanine-DNA-methyltransferase (MGMT) promoter methylation and presence of LAG-3+ TILs was observed (p = 0.726). LAG-3 expression was associated with the presence of CD3+ (p = 0.029), CD8+ (p = 0.001), PD-1+ (p < 0.001) TILs and PD-L1+ tumor cells (p = 0.021), respectively. No association of overall survival with LAG-3+ TIL infiltration was evident (median OS 9.9 vs. 14.2 months, p = 0.95).ConclusionsLAG-3 is only rarely expressed on TILs in IDH-wildtype glioma and associated with active inflammatory milieu as defined by higher TIL density. Immune microenvironment diversity should be considered in the design of future immunotherapy trials in glioma.

Abstract OT-03-02: Phase 1/2 study of a novel HER2 targeting TLR7/8 immune-stimulating antibody conjugate (ISAC), BDC-1001, as a single agent and in combination with an immune checkpoint inhibitor in patients with advanced HER2-expressing solid tumors

Abstract Background: To date, no immune-based therapies beyond anti-HER2 monoclonal antibodies are approved for treating patients (pts) with HER2-driven or -expressing cancers. However, pts still develop progressive disease, and new treatment options that could achieve durable antitumor efficacy are needed. Recent studies indicate that intratumoral delivery of immunostimulatory adjuvants such as toll-like receptor (TLR) 7/8 agonists can activate tumor resident antigen-presenting cells (APCs), driving uptake, processing, and presentation of tumor neoantigens to T cells that mediate antitumor immunity. To overcome limitations associated with intratumoral delivery while leveraging superior preclinical biology, BDC-1001, a novel, systemically delivered ISAC was developed. BDC-1001 consists of an investigational biosimilar of the humanized monoclonal antibody trastuzumab that is chemically conjugated to a TLR 7/8 agonist (payload) with an intervening non-cleavable linker. BDC-1001 activates human myeloid APCs while retaining antibody-mediated effector functions such as antibody-dependent cellular cytotoxicity/phagocytosis (ADCC/ADCP). Xenograft and syngeneic tumor resistant models indicate that trastuzumab ISACs elicit potent and durable immune-mediated antitumor efficacy including complete tumor regression in a TLR- and Fc receptor-dependent manner (Ackerman et al. Cancer Res. 2019:79 [13 Suppl]; Ackerman et al. J Immunother Cancer. 2019;7:283). Importantly, BDC-1001 did not induce interstitial lung disease, cytokine release syndrome, or thrombocytopenia in non-human primate studies. A four-part phase 1/2, first-in-human study has been initiated that evaluates BDC-1001 with or without (+/-) an immune checkpoint inhibitor targeting PD-1 in pts with HER2-expressing or HER2-amplified advanced/metastatic solid tumors. Study Description: This phase 1/2 dose-escalation and dose-expansion study is enrolling up to 390 pts with advanced solid tumors that are HER2-expressing (IHC2+ or 3+ protein irrespective of gene amplification) or HER2-amplified (by in situ hybridization or next-generation sequencing) and ineligible for approved anti-HER2 treatments. The primary objectives of the dose-escalation phase are to define safety and tolerability and to determine the recommended phase 2 dose of BDC-1001 as monotherapy (Part 1) and in combination with an immune checkpoint inhibitor (Part 2). Primary endpoints of Parts 1 and 2 include incidence of 1) adverse events and severe adverse events graded according to NCI CTCAE v5.0; 2) dose-limiting toxicities within a 3+3 design; and 3) potential immune-related toxicities. BDC-1001 is administered IV over 60 min q3w at increasing doses. Once safety data are available for BDC-1001, initiation of the immune checkpoint inhibitor combination is planned. The dose-expansion phase 2 portion of the trial will evaluate preliminary antitumor activity of BDC-1001 alone (Part 3) and in combination with an immune checkpoint inhibitor (Part 4) using RECIST v1.1 and iRECIST. The primary endpoint of this dose-expansion phase is overall response rate, with secondary endpoints of duration of response, disease control rate, and progression-free survival. Exploratory objectives will evaluate pharmacokinetic parameters and pharmacodynamic biomarkers associated with drug exposure. These exploratory studies will help elucidate the mechanism of action and seek to identify biomarkers to improve selection of pts most likely to benefit from treatment with BDC-1001 +/- immune checkpoint inhibitor. This global study is currently recruiting pts. For further information, visit ClinicalTrials.gov (NCT04278144). Citation Format: Ecaterina Ileana Dumbrava, Manish R. Sharma, Richard D. Carvajal, Daniel Catenacci, Leisha A. Emens, Shirish M. Gadgeel, Glenn J. Hanna, Dejan Juric, Yoon-Koo Kang, Jeeyun Lee, Keun-Wook Lee, Bob T. Li, Kathleen Moore, Mark D. Pegram, Paula R. Pohlmann, Drew Rasco, Alexander Spira, Antoinette R. Tan, Shelley E. Ackerman, Heidi LeBlanc, David Dornan, Marcin Kowanetz, Michael N. Alonso, Edith A. Perez. Phase 1/2 study of a novel HER2 targeting TLR7/8 immune-stimulating antibody conjugate (ISAC), BDC-1001, as a single agent and in combination with an immune checkpoint inhibitor in patients with advanced HER2-expressing solid tumors [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr OT-03-02.

Combination therapy with anti-T-cell immunoglobulin and mucin-domain containing molecule 3 and radiation improves antitumor efficacy in murine hepatocellular carcinoma.

T-cell immunoglobulin and mucin-domain containing molecule 3 (TIM3) has emerged as a promising immune checkpoint inhibitor target; however, immune checkpoint inhibitor monotherapy does not benefit a substantial percentage of patients. Therefore, this study investigated the antitumor effect of anti-TIM3 therapy combined with radiation in a murine hepatocellular carcinoma (HCC) model. The effect of radiation on TIM3 expression was determined in murine and human HCC cells using western blotting, immunohistochemistry, and flow cytometry. Tumor growth and survival rate were measured to evaluate the antitumor effect of this combination therapy. Tumor immunological parameters were assessed using flow cytometry and histology. TIM3 was upregulated in tumor-infiltrating CD8+ and CD4+ T cells in radiation-treated HCa-1-implanted mice. Combination treatment significantly delayed tumor growth compared with monotherapy (P<0.01). Overall survival was improved in the combination group compared with that in the anti-TIM3 or radiation monotherapy groups (median survival time: 52days vs 26 or 38days, respectively, P<0.001). The antitumor effect of the combination treatment was associated with increased apoptosis and decreased proliferation of tumor cells and reinvigorated CD8+ T-cell activation. CD8+ T-cell depletion reversed the antitumor efficacy of the combination treatment. These findings suggest that CD8+ T cells play key roles in the therapeutic effect of the combination treatment. Anti-TIM3 and radiation combination therapy significantly improved the antitumor effect in a murine HCC model, as evidenced by inhibited tumor growth and increased overall survival. This approach could be a novel combined immune-radiotherapy strategy for HCC.

TMOD-05. EXTRACRANIAL TUMORS INFLUENCE INTRACRANIAL RESPONSE TO IMMUNE CHECKPOINT INHIBITORS IN PRE-CLINICAL MODELS OF MELANOMA BRAIN METASTASIS

Abstract Melanomas frequently spread to the brain, with up to 75% of patients developing brain metastases. Treatment of metastatic melanoma has been revolutionized by the advent of immune checkpoint inhibitors (ICI) targeting PD-1 and CTLA-4. However, responses to ICI within the immune-specialized brain environment are not well understood owing to the lack of immunocompetent animal models for the investigation of intracranial responses to checkpoint blockade. We studied the effect of ICI in a syngeneic mouse model of melanoma brain metastasis with concurrent intracranial and subcutaneous tumors. Either D3UV3 cells, derived from a UVB irradiated clone of D4M.3A melanoma cell line, or vehicle were subcutaneously injected into the flank of C57BL/6 mice. 3 days later, D3UV3 cells tagged with firefly luciferase were implanted into the striatum using stereotactic injection. Mice were then treated with anti-PD-1 antibody, anti-CTLA-4 antibody, a combination of anti-PD-1 and anti-CTLA-4 antibodies, or isotype controls. We observed striking differences in survival between mice with concurrent intracranial and subcutaneous tumors compared to intracranial tumors alone. Mice with intracranial tumors alone experienced no benefit in survival following monotherapy with anti-PD-1 (p=1) or anti-CTLA-4 (p=0.1) compared to isotype-treated mice, and only a slight benefit with combination treatment (p=0.049). In contrast, mice with concurrent tumors experienced a significant increase in overall survival with anti-CTLA-4 monotherapy (p=0.01) and combination anti-CTLA-4 and anti-PD-1 treatment (p=0.01) compared to isotype-treated mice, although treatment with anti-PD-1 alone did not increase survival (p=0.28). These results indicate that the presence of extracranial disease can modulate intracranial immune responses following checkpoint blockade. We have therefore established a pre-clinical model with concurrent intracranial and extracranial tumors to better recapitulate the clinically observed context of brain metastases. We hope this model will lead to a better understanding of the setting in which ICI is effective for patients with melanoma brain metastases.