anti-CTLA4 Monoclonal Antibody Research Articles

A first-in-human, phase I, dose-escalation study to evaluate pharmacokinetics, safety, and tolerability of KD6001, a novel anti-CTLA-4 monoclonal antibody (mAb) in patients with advanced solid tumors.

e14501 Background: KD6001, a novel fully human anti-CTLA4 IgG1 monoclonal antibody, exhibits immunomodulatory effects, enhances T-cell-mediated antitumor immune response and shows promising activity in preclinical models of solid tumors. Here we present the pharmacokinetics, safety and tolerability data from the phase 1 study of KD6001 (NCT05230290) in patients with advanced solid tumors. Methods: patients were enrolled in a 3+3 dose escalation phase 1 study with the following pre-defined KD6001 cohorts: 0.2mg/kg, 1mg/kg, 3mg/kg or 6mg/kg, every 2 weeks via intravenous infusion for 4 cycles. The primary objective was to evaluate the safety and tolerability of KD6001 and determine the MTD/RP2D. The secondary objectives were to measure antitumor activity, immunogenicity and pharmacokinetics (PK). All AEs are graded using NCI CTCAE v5.0. Efficacy assessments are per RECIST 1.1. Blood samples are obtained for pharmacokinetics (PK) and for immunogenicity assessments, measured by the development of anti-drug antibodies. Results: The study had been completed. Thirteen pts with melanoma had been enrolled and treated at 0.2 mg/kg (n = 1), 1mg/kg (n = 3), 3 mg/kg (n = 6) and 6mg/kg (n = 3) at Beijing Cancer Hospital. The average age was 57.2 years (range 34-68). Baseline ECOG scores were 0 (n = 5), 1(n = 8) with all pts. Seven pts (53.85%) received ≥ 2 lines of previous systemic therapies and 12 pts (92.31%) received previous PD-1/PD-L1 treatment. KD6001 was well-tolerated with no dose-limiting toxicities (DLTs) observed, nor was the MTD reached at the highest doses administered. All the thirteen pts had at least one adverse event during treatment, and eleven of them (84.62%) had Treatment Related Adverse Events (TRAEs), most of which were Grades 1-2. There were no permanent drug discontinuation or deaths due to adverse events. Pharmacokinetic analysis indicated a linear correlate between the drug exposure (Cmax, AUC0-t and AUC0-inf) and study drug dosages evaluated. The geometric mean T1/2 was 10 days (CV%: 31%). The peak concentration and exposure level increased proportionally to dose from 0.2mg/kg to 6 mg/kg. No anti-drug antibodies were detected in any of the patient’s serum samples. Clinical efficacy was observed in 12 evaluable pts: 3 patients at 3mg/kg had a stable disease (SD) and 1 patient at 3mg/kg had a confirmed partial response (PR). The ORR of the 3mg/kg dose group was 16.7% (1/6), the DCR was 66.67% (4/6). The median PFS was 109 days and the median OS was not reached. Conclusions: KD6001 showed promising antitumor activity and a tolerable safety profile in patients with advanced solid tumors. Hence, 3mg/kg was selected as the RP2D. Clinical trial information: NCT05230290 .

A phase I/II study of KD6001, a novel fully human anti-CTLA4 IgG1 monoclonal antibody, in combination with toripalimab in patients with advanced melanoma.

9527 Background: Anti-CTLA4 and anti-PD-1 immunotherapies have changed the treatment landscape of patients (pts) with advanced or metastatic melanoma. However, there is still a need to develop an anti-CTLA-4 antibody with further improved safety and efficacy profile. KD6001, a novel fully human anti-CTLA4 IgG1 monoclonal antibody that exhibits immunomodulatory effects, enhances T-cell-mediated anti-tumor immune response, and shows preliminary anti-tumor activity as monotherapy in a FIH phase I trial in pts with advanced solid tumors. Here we report a new study result of KD6001 in combination with toripalimab, an anti-PD-1 monoclonal antibody, in pts with advanced melanoma (KD6001CT02). Methods: KD6001CT02 is a phase I/II study conducted in advanced melanoma. This study consists of dose escalation and dose expansion phases. The primary objective is to evaluate the safety and tolerability of KD6001 in combination with toripalimab and determine the MTD/RP2D. The secondary objectives are to measure antitumor activity, immunogenicity, and pharmacokinetics (PK). Results: As of 15 Dec 2023, 29 pts with melanoma were enrolled (dose escalation n=6 and dose expansion n=23), including 9 (31.0%) acral, 9 (31.0%) nonacral cutaneous, 8 (27.6%) mucosal, and 3 (10.3%) unknown primary subtypes. 18 of them had no brain metastases. The median age was 56 yrs (range 41-78 yrs). The majority of pts previously received anti-PD-1/L1 therapy (16/29, 55.2%) and 27.6% of them received ≥3 lines of therapy. No dose-limiting toxicity or ≥Gr 3 adverse events (AEs) were reported in the dose escalation phase. The study did not reach MTD. 26 (89.7%) pts had treatment-related adverse events (TRAEs), with ≥Gr 3 TRAEs occurring in 3 (10.3%) pts and were well manageable. All other TRAEs were Gr 1 or 2. There were no death events due to TRAEs. No novel safety signals were seen other than the previously reported safety profile of treatment with a combined inhibition of CTLA-4 and PD-1. At data cutoff, among 13 efficacy-evaluable pts without brain metastases, the unconfirmed and confirmed objective response rates (ORR) were 38.5% and 23.1%, respectively. The disease control rate (DCR) was 76.9%. Among 3 pts with confirmed partial response (PR) , 2 pts were mucosal melanoma and 1 patient was nonacral cutaneous melanoma. Among 7 pts who received KD6001 as the ≥2 line treatment and all failed anti-PD-1/L1 therapy, the unconfirmed and confirmed ORR were 57.1% and 42.9%, respectively. DCR was 85.7%. The median PFS and OS were not reached. Conclusions: KD6001 in combination with toripalimab for treatment of advanced melanoma was safe, well-tolerated and showed anti-tumor activity in pts with advanced melanoma. Preliminary analysis indicates that KD6001 combined with toripalimab is efficacious in pts who have progressed after previous anti-PD-1/L1 therapy and in pts with mucosal melanoma. Clinical trial information: NCT05723432 .

Effect of anti CTLA-4 and PD-1 monoclonal antibodies on systemic SDF-1 and galectin-3 levels through NLRP3 and MyD-88 pathways in preclinical models.

Effect of anti CTLA-4 and PD-1 monoclonal antibodies on systemic SDF-1 and galectin-3 levels through NLRP3 and MyD-88 pathways in preclinical models.

'Immunotherapeutic Strategies for Intra-cranial Metastatic Melanoma - a Meta-analysis and Systematic Review'.

Immune-activating anti-CTLA4 and anti-PD1 monoclonal antibodies (alone or in combination) are being used to treat advanced melanoma patients and can lead to durable remissions, and long-term overall survival may be achieved in between 50-60% of patients. Although intracranial metastases are very common in melanoma (about 50-75% of all patients with advanced disease), most of the pivotal prospective clinical trials exclude patients with intra-cranial metastases, certainly if their lesions are symptomatic and steroid-requiring and the degree of sensitivity of intra-cranial melanoma to immunotherapy remains uncertain, and requires further investigation especially in view of the demonstrable activity of RAF-MEK inhibitors in this clinical setting and the emergence of stereotactic radiotherapy. Our study aimed to evaluate the efficacy and toxicity of immunotherapy against advanced melanoma patients with brain metastases. In terms of comparative studies, only retrospective analyses could be identified. Based on 3 retrospective studies, treatment of patients with melanoma brain metastases with immunotherapeutic approaches improves overall survival substantially compared with supportive measures alone (no active anticancer treatment). The efficacy of targeted therapy appeared to be comparable to that of immune therapy in terms of overall survival, based on a small number of patients. The combination of concurrent radiation therapy to the brain and systemic immunotherapy led to improved overall survival compared to radiotherapy alone, suggesting potential synergism between the approaches, and combination treatment could be delivered safely. Our review supports the use of immunotherapeutic strategies for these patients although treatment efficacy appears to be lower for symptomatic lesions. In view of the extremely high efficacy of stereotactic radiotherapy approaches in the brain, understanding the interaction between radiotherapy and immunotherapy is vital and should be an area of active investigation.

Anti CTLA-4 and PD-1 monoclonal antibodies increases systemic SDF-1 and galectin-3 levels and reduces myocardial strain through NLRP3 and MyD-88 pathways

Abstract Background Immune checkpoint inhibitors (ICIs) have significantly changed the oncology clinic in recent years, improving survival expectations in cancer patients. ICI therapy have a broad spectrum of side effects from endocrinopathies to cardiovascular diseases. Purpose In this study, pro-inflammatory and pro-fibrotic effects of short-term ICIs therapy in preclinical models were analyzed. Methods Firstly, in a human in vitro model, human cardiomyocytes co-cultured with hPBMC were exposed to ICIs (with CTLA-4 or PD-1 blocking agents, at 200 nM) for 72h. After treatment, production of DAMPs and 12 cytokines were analyzed in the supernatant through colorimetric and enzymatic assays. C57/Bl6 mice were treated with CTLA-4 or PD-1 blocking agents (15 mg/kg) for 10 days. Before (T0), after three days (T3) and after treatments (T10), ejection fraction, fractional shortening, radial and longitudinal strain were calculated by using bidimensional echocardiography (Vevo 2100,Fujfilm). Fibrosis, necrosis, hypertrophy and vascular NF-kB expression were analyzed through Immunohistochemistry. Myocardial expression of DAMPs (S100- Calgranulin, Fibronectin and Galectine-3), MyD88, NLRP3 and twelve cytokines have been analyzed. Systemic levels of SDF-1, IL-1β and IL-6 were analyzed before, during and after ICIs therapy. Results Radial and longitudinal strain were decreased after 10 days of ICIs therapy. Histological analysis of NF-kB expression shows that short-term anti-CTLA-4 or anti-PD-1 treatment increased vascular and myocardial inflammation. No myocardial hypertrophy was seen with the exception of the pembrolizumab group. Myocardial fibrosis and expression of galectin-3, pro-collagen 1-α and MMP-9 were increased after treatment with all ICIs. Both anti-CTLA-4 or anti-PD-1 treatments increased the expression of DAMPs, NLRP3 inflammasome and MyD88 and induced both in vitro and in vivo the secretion of IL-1β, TNF-α and IL-6. Systemic levels of SDF-1, IL-1β and IL-6 were increased during and after treatment with ICIs. Conclusions Short therapy with PD-1 and CTLA-4 blocking agents increases vascular expression of NF-kB, systemic SDF-1, IL-1β, IL-6 levels and myocardial NLRP3, MyD88 and DAMPs expression in preclinical models. A pro-inflammatory cytokine storm was induced in myocardial tissues and in cultured cardiac cells after ICIs therapy. The overall picture of the study suggests new putative biomarkers of ICIs-mediated systemic and myocardial damages potentially useful in clinical cardioncology.

Abstract 15045: Anti CTLA-4 and PD-1 Monoclonal Antibodies Increases Systemic SDF-1 and Galectin-3 Levels and Reduces Myocardial Strain Through NLRP3 and MyD-88 Pathways

Background: Immune checkpoint inhibitors (ICIs) have significantly changed the oncology clinic in recent years, improving survival expectations in cancer patients. ICI therapy have a broad spectrum of side effects from endocrinopathies to cardiovascular diseases. In this study, pro-inflammatory and pro-fibrotic effects of short-term ICIs therapy in preclinical models were analyzed. Methods: Firstly, human cardiomyocytes co-cultured with hPBMC were exposed to ICIs (with CTLA-4 or PD-1 blocking agents, at 200 nM) for 72h. After treatment, production of DAMPs and 12 cytokines were analyzed in the supernatant through enzymatic assays. C57/Bl6 mice were treated with CTLA-4 or PD-1 blocking agents (15 mg/kg) for 10 days. Before (T0), after three days (T3) and after treatments (T10), ejection fraction, fractional shortening, radial and longitudinal strain were calculated by using bidimensional echocardiography (Vevo 2100,Fujfilm). Fibrosis, necrosis, hypertrophy and vascular NF-kB expression were analyzed through Immunohistochemistry. Myocardial expression of DAMPs, MyD88, NLRP3 and twelve cytokines have been analyzed. Systemic levels of SDF-1, IL-1β and IL-6 were analyzed before, during and after ICIs therapy. Results: Radial and longitudinal strain were decreased after 10 days of ICIs therapy. Histological analysis of NF-kB expression shows that short-term anti-CTLA-4 or anti-PD-1 treatment increased vascular and myocardial inflammation. No myocardial hypertrophy was seen with the exception of the pembrolizumab group. Myocardial fibrosis and expression of galectin-3, pro-collagen 1-α and MMP-9 were increased after treatment with all ICIs. Both anti-CTLA-4 or anti-PD-1 treatments increased the expression of DAMPs, NLRP3 and MyD88 and induced both in vitro and in vivo the secretion of IL-1β, TNF-α and IL-6. Systemic levels of SDF-1, IL-1β and IL-6 were increased during and after treatment with ICIs. Conclusions: Short therapy with PD-1 and CTLA-4 blocking agents increases vascular expression of NF-kB, systemic SDF-1, IL-1β, IL-6 levels and myocardial NLRP3, MyD88 and DAMPs expression in preclinical models. A pro-inflammatory cytokine storm was induced in myocardial tissues after ICIs therapy.

2244P Anti CTLA-4 and PD-1 monoclonal antibodies increases systemic SDF-1 and galectin-3 levels through NLRP3 and MyD-88 pathways in preclinical models

2244P Anti CTLA-4 and PD-1 monoclonal antibodies increases systemic SDF-1 and galectin-3 levels through NLRP3 and MyD-88 pathways in preclinical models

E010 Checkpoint inhibitor-induced rheumatological adverse events: real-world experience from Northeast England

Abstract Background/Aims Immune checkpoint inhibitors (CPIs), in the form of either single agent anti-PD1 or combination therapy with anti-PD1/anti-CTLA4 monoclonal antibodies, are widely used in clinical practice. Whilst CPI-induced rheumatological immune-related adverse events (RirAEs) are relatively infrequent compared to other toxicities (8-12%), increasing CPI use in oncology settings means a growing number of patients are affected. As part of an audit of inter-specialty referrals, we evaluated patients developing new musculoskeletal symptoms on CPI treatment and the breadth of specialist-confirmed RirAEs. Methods Two sources of data were reviewed. First, consecutive consultant-confirmed RirAE cases in our rheumatological service between 2017 and 2022 (referred to as the ‘RirAE cohort’) were evaluated. Second, an observational cohort of 50 consecutive oncology patients treated with CPIs from 2019-2022 in whom symptom questionnaires had been completed (“Oncology cohort”) was reviewed. Local audit registration/safeguarding approvals were obtained. Medical records were reviewed by two medical professionals, and anonymised data analysed in a spreadsheet. Results 24 patients were identified in the RirAE cohort, of whom most presented with arthritis (Table 1). Amongst 50 patients in the Oncology cohort, 20 (40%) reported new-onset/worsening musculoskeletal symptoms on a questionnaire (“MSK-symptomatic Oncology Cohort”). Three of these were referred, diagnosed and counted amongst the RirAE cohort. Of the remaining 17, 6 were identified as having developed musculoskeletal pain by consulting oncologists; the remaining 11 were not objectively identified as having experienced potential musculoskeletal toxicity (Table 1). Conclusion Confirmed RirAEs comprised predominately seronegative, oligoarticular presentations with notable PMR overlap. In the oncology setting, the self-reported joint symptoms of 20/50 (40%) patients were identified by a physician and 3/9 of these (33%) were referred for a specialist opinion. RirAEs may be more common than appreciated amongst CPI recipients, and the extent of low-grade inflammatory arthritis unreported or “hidden” amongst other irAEs is not clear. Early evaluation of new-onset musculoskeletal symptoms in CPI recipients, and close cross-specialty collaboration, could reduce morbidity for patients who already face significant health challenges. Disclosure A. Gault: None. K. Williams: None. C. Stewart: None. A.E. Anderson: None. R. Plummer: None. A.G. Pratt: None.

Neo-Adjuvant immunotherapies: Bladder cancer as a platform for drug development targeting mucosal immunity

Bacillus Calmette-Guerin (BCG) is a live attenuated Mycobacterium bovis strain, originally developed as a vaccine against tuberculosis. It is also the only bacterial cancer therapy approved by the US Food & Drug Administration for clinical use. BCG is delivered in the bladder, shortly after tumour resection, for patients with high-risk non-muscle invasive bladder cancer (NMIBC). Modulating mucosal immunity by exposing the urothelium to intravesical BCG has been the main therapeutic strategy for high-risk NMIBC over the last three decades. Thus, BCG provides a benchmark for the clinical development of bacteria—or other live attenuated pathogens—as cancer therapy. Currently, a myriad of immuno-oncology compounds is under clinical evaluation in BCG-unresponsive and BCG-naïve patients as an alternative therapy in the context of worldwide BCG shortages. For patients with non-metastatic muscle-invasive bladder cancer (MIBC), studies investigating neoadjuvant immunotherapy with either anti–PD-1/PD-L1 monoclonal antibodies in monotherapy or in combination with anti–CTLA-4 monoclonal antibodies have shown overall efficacy and acceptable safety profiles prior to radical cystectomy. Emerging clinical investigations are testing synergistic approaches by combining intravesical delivery of drugs with systemic immune checkpoint blockades in the neoadjuvant setting for patients with MIBC. Such novel strategy aims to prime a local anti-tumour immunity and reduce distant metastatic relapses by enhancing a systemic adaptive anti-tumour immune response. Here, we present and discuss some of the most promising clinical trials developing such novel therapeutic approaches.

Abstract 4850: High salt diet induced tumor initiating stem cells mediate breast cancer progression

Abstract High-salt (sodium chloride) diets have been associated with several chronic inflammatory diseases. While the role of chronic inflammation in cancer is well established, the specific role of high salt diet in carcinogenesis is unknown. Previous studies with syngeneic murine breast cancer models, both in our laboratory and others, have shown that high salt (HS) diet induced tumor regression through inflammatory activation of anti-tumor adaptive immune responses. We tested this counter-intuitive and suspiciously beneficial role of HS diet by performing sequential passage studies in preclinical murine models. Six week old mice were placed on high salt diet for 2 weeks prior to injection with syngeneic 4T1 and Py230 triple negative breast cancer cells (into BALB/c and C57Bl/6J mice, respectively, referred to as passage-1). Tumors were harvested after four weeks of injection. The cancer cells depleted of immune cells were collected from these harvested tumors and reinjected into new non-tumor bearing mice. This cycle was repeated three times. In passage-1 cohort, by day 28, HS diet induced reduced tumor progression in both 4T1-BALB/c (267 ± 59 mm3) and Py230-C57Bl/6J (238 ± 54 mm3) as compared to regular salt (RS) diet cohort (611 ± 94 mm3 and 473 ± 69 mm3, respectively; p<0.05 for both). However, in passage-4 cohort, by day 28, HS diet induced significantly higher tumor progression in both 4T1-BALB/c (806 ± 91 mm3) and Py230-C57Bl/6J (743 ± 81 mm3) models, as compared to regular salt (RS) diet cohort (577 ± 83 mm3 and 462 ± 77 mm3, respectively; p<0.05 for both). Cellular analysis by flow cytometry revealed that there was a 12-19 fold increase in tumor initiating stems cells (TISCs) in passage-4 HS diet cohort compared to RS diet cohort. Mechanistic studies have demonstrated that there was increased TGFβ expression on TISCs obtained from passage-4 HS diet cohort which correlated with enhanced exhaustion phenotype (CTLA4+) of tumor infiltrating adaptive immune cells (CD4 and CD8 T cells) in this cohort. Co-treatment with anti-TGFβ and anti-CTLA4 monoclonal antibodies (mAb) in passage-4 HS diet cohort, significantly reduced tumor progression (p<0.05), as compared to treatment with either mAb alone. Taken together, these data demonstrated that chronic HS diet leads to expansion of TGFβ expressing TISCs leading to host immune exhaustion and tumorigenesis. Importantly, anti-TGFβ mAb exerted a favorable synergistic effect to enhance the anti-tumor efficacy of immune check-point inhibitors. Citation Format: Lisa Tucker, Sonya Reid, Jeffrey C. Rathmell, Venkataswarup Tiriveedhi. High salt diet induced tumor initiating stem cells mediate breast cancer progression. [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 4850.

Cutaneous Melanoma and Hormones: Focus on Sex Differences and the Testis.

Cutaneous melanoma, the most aggressive type of skin cancer, remains one the most represented forms of cancer in the United States and European countries, representing, in Australia, the primary cause of cancer-related deaths. Recently, many studies have shown that sex disparities previously observed in most cancers are particularly accentuated in melanoma, where male sex is consistently associated with an increased risk of disease progression and a higher mortality rate. The causes of these sex differences rely on biological mechanisms related to sex hormones, immune homeostasis and oxidative processes. The development of newer therapies, such as immune checkpoint inhibitors (ICIs) (i.e., anti-PD-1 and anti-CTLA-4 monoclonal antibodies) has dramatically changed the treatment landscape of metastatic melanoma patients, though ICIs can interfere with the immune response and lead to inflammatory immune-related adverse events (irAEs). Recently, some studies have shown a potential adverse influence of this immunotherapy treatment also on male fertility and testicular function. However, while many anticancer drugs are known to cause defects in spermatogenesis, the effects of ICIs therapy remain largely unknown. Notwithstanding the scarce and conflicting information available on this topic, the American Society of Clinical Oncology guidelines recommend sperm cryopreservation in males undergoing ICIs. As investigations regarding the long-term outcomes of anticancer immunotherapy on the male reproductive system are still in their infancy, this review aims to support and spur future research in order to understand a potential gonadotoxic effect of ICIs on testicular function, spermatogenesis and male fertility.

Impact and Novel Perspective of Immune Checkpoint Inhibitors in Patients with Early and Intermediate Stage HCC.

Simple SummaryThe prognostic evaluation and therapeutic management of hepatocarcinoma (HCC) is based on the Barcelona Liver Cancer Clinic (BCLC). In the past years, immunotherapy has become a mainstay of first-line treatment in advanced HCC and further treatment options are underway. Beyond this, the scientific community is more and more focusing on immunotherapeutic approaches in earlier HCC stages. The purpose of this review is to describe the rationale for immunotherapeutic approaches and the studies conducted with immunotherapy in patients with early and intermediate stage HCC.Surgery and radiofrequency ablation remain the gold standard to achieve cure in patients with hepatocellular carcinoma (HCC). After a decade in which only sorafenib was available for advanced and metastatic HCC, the emergence of other molecularly targeted drugs and immune checkpoint inhibitors (ICIs) has significantly improved the patients` prognosis. In particular, the use of ICIs has shown promising results and has revolutionized the treatment algorithm in HCC patients. Indeed, preclinical and clinical data have documented a high density of immunosuppressive cells and an increased expression of the programmed death-1 (PD-1) receptor and cytotoxic T-cell associated protein-4 (CTLA-4) in HCC. However, despite these observations, no validated biomarker is available and the molecular groundwork responsible for response to ICIs remains elusive. The anti-CTLA4 monoclonal antibody tremelimumab and the anti-PD-1 monoclonal antibodies nivolumab and pembrolizumab were the first ICIs to be tested in HCC. Recently, the combination of the anti-programmed death-ligand 1 (PD-L1) inhibitor atezolizumab and the anti-vascular endothelial growth factor (VEGF) antibody bevacizumab demonstrated an improvement in patient outcome compared to sorafenib, becoming the standard of care in the frontline setting of advanced disease. Other immunotherapeutic agents such as pembrolizumab or the combination nivolumab-ipilimumab have shown promising results that have to be confirmed in phase III studies. Currently, the combination of different ICIs (i.e., ipilimumab, durvalumab) and anti-angiogenic agents (i.e., regorafenib, lenvatinib) is currently being tested in several trials and will hopefully revolutionize the treatment of HCC. To date, numerous studies are underway evaluating ICIs in adjuvant and neoadjuvant settings to improve survival in early and intermediate stages. Thus, this review focuses on the rationale for ICIs and their potential use for early or intermediate HCC stages.

Early Regulatory and Memory T Cell Profiles Post-ASCT in the Presence of Checkpoint Inhibitor (Nivolimumab+Ipilimumab) Double Therapy in Patients with High-Risk Multiple Myeloma

BACKGROUNDMultiple myeloma (MM) is a hematological malignancy characterized by the uncontrolled growth of clonal plasma cells. High-dose chemotherapy followed by autologous stem cell transplantation (ASCT) is now standard of care for newly diagnosed MM patients with improved outcome. However, high-risk MM patients relapse after 1 to 2 years post-ASCT. Immune checkpoint blockade using nivolumab (Nivo), an anti-PD1 monoclonal antibody or ipilimumab (Ipi), an anti-CTLA4 monoclonal antibody, as single agents have achieved durable responses in patients with advanced solid tumors. RATIONALEIn a murine melanoma model, Nivo or Ipi monotherapy partially reduced tumor burden, whereas combined Nivo and Ipi therapy eliminated tumor burden. In patients with advanced cancers such as melanoma and non-small lung cancer, combined Nivo+Ipi resulted in superior clinical efficacy compared to patients treated with single agents. Since monotherapy with Nivo did not show an objective response rate in relapsed/refractory MM patients, we hypothesized that high-risk MM patients treated with consolidation therapy consisting of Nivo plus Ipi post-ASCT would achieve a more durable response and improve progression-free survival. OBJECTIVEWhile the objective of the clinical trial focused on safety and efficacy of the combination therapy approach, our study focused on blood immune analysis by flow cytometry, and particularly on the regulatory (Treg) and memory T cell compartments. STUDY DESIGNIn a phase Ib-IIA study, patients were grouped into 6 cohorts (7 patients each) with various hematological malignancies. This abstract focuses on results from the transplant-naive high-risk MM group: those carrying 1q amplifications, 1p, 13q, or p53 deletions, high-risk GEP 70 scores, t(4;14), t(14;16) and t(14;20), or hypodiploidy). Peripheral blood (PB) samples obtained from patients at time of initial screening served as a baseline (PB0). The patients underwent hematopoietic progenitor cell (HPC) mobilization (high-dose cyclophosphamide, dexamethasone and etoposide followed by filgrastim), apheresis, conditioning with melphalan 200 mg/m2, and HPC reinfusion. Starting 2-4 wks later, they were administered double therapy (Ipi. 1mg/kg; 6 doses at week 1, 4, 7, 10, 16, 22 and Nivo. 3 mg/kg; 12 doses at week 1, 4, 7, 10, 12, 14, 16, 18, 20, 22, 24, 26). PB was collected just prior to any treatment at various time points (see Figure), and normal healthy donor PB served as population standards for flow cytometry. PRELIMINARY RESULTSThis information includes the reported % mean + interquartile range data for the high risk MM group up to week 26, given that the study is still on-going. Thus far, the gated % of Tregs CD4+RO+CD25+CD127- decreased throughout the therapy: 1.4%, (PB0), 0.1%, (PB4), 0.3%, (PB7), 0.4%, (PB18), 0.1%, (PB26). Moreover, the CD4+CD39+RO+ (Memory) Tregs initially decreased and then rebounded with double therapy administration: 69%, (PB0), 54% (PB4), 68% (PB7), 68% (PB18), and 51% (PB26). Moreover, the percent of CTLA4+RO+ Tregs was altered after the first combination treatment: 3.2% (PB0), 1.3% (PB4), 0% (PB7), but was restored by PB18 (3.0%) and PB26 (3.6%). Similar results were observed in the absolute numbers of these populations. Furthermore, there was a marked increase in CD4+ effector memory (EM) T cells at PB4 (5.5%) and PB18 (4.5%) compared to PB0 (4.0%). And CD8+ EM T cells were not affected at PB4 (1.1%) and PB18 (1%), compared to PB0 (1.1%). In contrast, both CD8+ and CD4+ central memory (CM) T cell compartments were low at all time points. Interestingly, while CD4+CCR7+RO- terminally differentiated (TEMRO-) T cells did not recover to PB0 levels, the %CD8+CCR7+RO- TEMRO- T cells steadily increased up to PB18, but then decreased by PB26: 1.8% (PB0), 2.4%(PB7), 2.5%(PB18), and 1.2%(PB26). Similar results were observed using the absolute number of cells. CONCLUSIONSCombination Nivo+Ipi checkpoint inhibitors can decrease the presence of memory Tregs overall as well as CTLA4+ Tregs. In addition, the approach was able to increase the percentage and absolute numbers of the CD4/CD8 EM T cell compartments, but did not affect the CD4/CD8 CM T cell compartments, thus enabling the immune system to potentially still be able to target cancer cells while in therapy. Finally, the increase in CD8+ TEMRO- T cells were consistent with the exhaustion of longer surviving EM T cells. [Display omitted] DisclosuresBiran:Celgene, Amgen: Consultancy, Speakers Bureau; Takeda: Speakers Bureau. Richter:Amgen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Speakers Bureau; Takeda: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Speakers Bureau. Siegel:Celgene, Takeda, Amgen Inc, Novartis and BMS: Consultancy, Speakers Bureau; Merck: Consultancy. Skarbnik:Gilead: Speakers Bureau; Genentech: Speakers Bureau; Abbvie: Other: Ad board, Speakers Bureau; Novartis: Speakers Bureau; Seattle Genetics: Speakers Bureau.

Introducing immunotherapy for advanced hepatocellular carcinoma patients: Too early or too fast?

Advanced hepatocellular carcinoma (HCC) is the most frequent liver cancer. Immunotherapy has been explored in this disease in order to improve survival outcomes. Nowadays, scientific research is focusing especially on immune checkpoint inhibitors, in particular anti-PD1, anti-PD-L1 and anti-CTLA4 monoclonal antibodies (mAbs), as single-agent or in combination with other immunotherapy agents, target therapies, anti-vascular endothelial growth factor (VEGF) and other agents targeting specific molecular pathways. Other immunotherapy strategies have been assessed or are under investigation in advanced HCC, namely cytokines, adoptive cell therapy, oncolytic virus, cancer vaccines. Each treatment presents specific efficacy and toxicity profiles, strictly related to their mechanism of action and to advanced HCC tumour microenvironment (TME). The aim of this review is to outline the state-of-the-art of immunotherapy in advanced HCC treatment, highlighting data on already investigated treatment strategies, safety and toxicity (including HBV/HCV-related HCC), and ongoing clinical trials focusing on new promising therapeutic weapons.

Biological and molecular studies on specific immune cells treated with checkpoint inhibitors for the thera-personal approach of breast cancer patients (ex-vivo study).

The study was designed to optimize the condition for producing an effective dendritic cell (DCs) based immunotherapy by using DCs and T lymphocytes together with tumor-infiltrating lymphocytes (TILs) and tumor-infiltrating DCs (TIDCs), treated with anti-PD1 and anti-CTLA4 monoclonal antibodies. This mixture of immune cells was co-cultured with autologous breast cancer cells (BCCs) isolated from 26 BC females. There was a significant upregulation of CD86 and CD83 on DCs (p = 0.001 and 0.017, respectively), similarly upregulation of CD8, CD4 and CD103 on T cells (p = 0.031, 0.027, and 0.011, respectively). While there was a significant downregulation of FOXP3 and combined CD25.CD8 expression on regulatory T cells (p = 0.014 for both). Increased CD8/Foxp3 ratio (p < 0.001) was also observed. CD133, CD34 and CD44 were downregulated on BCCs (p = 0.01, 0.021, and 0.015, respectively). There was a significant increase in interferon-γ (IFN-γ, p < 0.001), lactate dehydrogenase (LDH, p = 0.02), and a significant decrease in vascular endothelial growth factor (VEGF, p < 0.001) protein levels. Gene expression of FOXP3 and Programmed cell death ligand 1 (PDL-1) were downregulated in BCCs (p < 0.001, for both), similarly cytotoxic T lymphocyte antigen-4 (CTLA4, p = 0.02), Programmed cell death 1 (PD-1, p < 0.001) and FOXP3 (p < 0.001) were significantly downregulated in T cells. Ex-vivo activation of immune cells (DCs, T cells, TIDCs, and TILs) with immune checkpoint inhibitors could produce a potent and effective BC immunotherapy. However, these data should be validated on an experimental animal model to be transferred to the clinical setting.

Combination of radiotherapy and suppression of Tregs enhances abscopal antitumor effect and inhibits metastasis in rectal cancer

BackgroundDistant metastasis is the major cause of mortality in patients with locally advanced rectal cancer (LARC) following neoadjuvant chemoradiotherapy. Local radiotherapy can trigger an abscopal response to metastatic tumor cells....

Abstract 4551: Preclinical characterization of novel anti-CTLA-4 prodrug antibodies with an enhanced therapeutic index

Abstract Background: Blockade of the CTLA-4 pathway with ipilimumab (IPI) as monotherapy or in combination with nivolumab (anti–PD-1) is an effective treatment for a variety of cancers. To enhance the therapeutic index of CTLA-4–directed therapy, a proprietary Probody® therapeutics (PB-Tx) technology platform was used to generate anti–CTLA-4 monoclonal antibodies (mAbs) with a masking peptide to attenuate CTLA-4 binding in the periphery. Increased protease activity in the tumor microenvironment is hypothesized to preferentially cleave the masking peptide. Here, we describe the preclinical characterization of 2 novel anti–CTLA-4 PB mAbs: anti–CTLA-4 PB (BMS-986249) is a peptide-masked version of IPI, and anti–CTLA-4 nonfucosylated (NF) PB (BMS-986288) is a peptide-masked version of anti–CTLA-4 NF, which has enhanced antibody-dependent cellular cytotoxicity (ADCC) and regulatory T-cell (Treg) depletion compared with IPI. Methods: Antibody binding to CD16 was studied by surface plasmon resonance. IL-2 release from staphylococcal enterotoxin B (SEB)–stimulated normal human peripheral blood mononuclear cells (PBMCs) and CD4+ T cells was measured; ADCC function was evaluated by IL-2–activated, NK-cell–induced lysis of CD4+ T cells or activated CD4+Foxp3+ Tregs. Tumor growth was measured in transgenic (human CTLA-4 knock-in) mice implanted with MC38 tumors. Peripheral pharmacodynamic (PD) markers (ICOS, Ki-67) of anti–CTLA-4 activity were assessed using Tregs and effector T cells from the spleens of treated mice. PD was evaluated in cynomolgus (CYNO) macaques after administration of customized adenovirus-5 vector vaccines. Results: With the masking peptide intact, both anti–CTLA-4 PB and anti–CTLA-4 NF PB showed decreased activity vs IPI and anti–CTLA-4 NF, respectively, in non–protease containing in vitro assays. Anti–CTLA-4 PB exhibited a 40-fold reduction in CTLA-4 binding affinity vs IPI and decreased activity in SEB-activated PBMCs. Anti–CTLA-4 NF PB showed decreased ADCC activity vs anti–CTLA-4 NF in vitro. When tested in a MC38 tumor model, anti–CTLA-4 PB and anti–CTLA-4 NF PB showed equivalent antitumor activity to IPI and anti–CTLA-4 NF, respectively. Both anti–CTLA-4 PB and anti–CTLA-4 NF PB showed equivalent intratumoral PD activity and reduced peripheral PD activity relative to their parental mAbs. Similarly, anti–CTLA-4 PB and anti–CTLA-4 NF PB resulted in reduced inflammation and peripheral PD responses relative to their parental mAbs in CYNO macaques. Conclusion: These data demonstrate the potential of the PB-Tx technology platform to improve the therapeutic indices of anti–CTLA-4 PB and anti–CTLA-4 NF PB relative to their parental mAbs. The safety and antitumor activity of anti–CTLA-4 PB (NCT03369223) and anti–CTLA-4 NF PB (NCT03994601) are being investigated in patients with advanced solid cancers in ongoing phase 1 studies. Citation Format: John Engelhardt, Rahima Akter, John Loffredo, Natalie Bezman, Paula So, Kimberly Tipton, Bryan Irving, James West, Wendy Freebern, Todd Bunch, Karen Price. Preclinical characterization of novel anti-CTLA-4 prodrug antibodies with an enhanced therapeutic index [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4551.

Biomarkers of Prognosis and Efficacy of Anti-angiogenic Therapy in Metastatic Clear Cell Renal Cancer.

In the last decades, the prognosis of metastatic renal cell carcinoma (mRCC) has remarkably improved following the advent of the “targeted therapy” era. The expanding knowledge on the prominent role played by angiogenesis in RCC pathogenesis has led to approval of multiple anti-angiogenic agents such as sunitinib, pazopanib, axitinib, cabozantinib, sorafenib, and bevacizumab. These agents can induce radiological responses and delay cancer progression for months or years before onset of resistance, with a clinically meaningful activity. The need for markers of prognosis and efficacy of anti-angiogenic agents has become more compelling as novel systemic immunotherapy agents have also been approved in RCC and can be administered as an alternative to angiogenesis inhibitors. Anti PD-1 monoclonal antibody nivolumab has been approved in the second-line setting after tyrosine kinase inhibitors failure, while combination of nivolumab plus anti CTLA-4 monoclonal antibody ipilimumab has been approved as first-line therapy of RCC patients at intermediate or poor prognosis. In this review article, biomarkers of prognosis and efficacy of antiangiogenic therapies are summarized with a focus on those that have the potential to affect treatment decision-making in RCC. Biomarkers predictive of toxicity of anti-angiogenic agents have also been discussed.

313P - Immunotherapy application for advanced cancers: One institution experiences since 2016 to 2019

BackgroundImmunotherapy has brought clinical benefits in several kinds of advanced cancers, including melanoma, renal cell carcinoma, non-small cell lung cancer, gastric cancer, HNSCC, esophageal cancer, hepatocellular carcinoma, and urinary tract cancers. Reliable biomarkers, best sequencing, and novel combinations for cancer immunotherapy warrant further investigation. Our group will present immunotherapy experiences for advanced cancers since 2016 to 2019 to show possible clinical impacts, choices of several combinations, toxicity profiles, favorable cancer types, and potential biomarkers exploratio. MethodsSince Jan 2016 to Feb 2019, we reviewed the details of immunotherapy(anti-PD1or anti-PDL1 or anti-CTLA4 monoclonal antibody) application from cancer patients in Yin-lin Branch of National Taiwan University Hospital. ResultsTotal 153 refractory cancer patients were collected due to previous or current use of immunotherapy. 69 patients received pembrolizumab(33 with triweekly 2 mg/kg & 36 with triweekly 200 mg); 74 received nivolumab(from 20 mg totally to 3 mg/kg biweekly); 2 ever received pembrolizumab and then nivolumab with ipilimumab; 1 ever received pembrolizumab and then pembrolizumab with ipilimumab; 5 received atezolizumab(2 NSCLC, 1 SCLC, 2 urinary tract cancers); 2 durvalumab (NSCLC). The cancer types were listed as following: 32 NSCLC(11 SCC, 19 adenocarcinoma, 1 adenosquamous, 1 pleomorphic); 2 SCLCs; 30 HNSCC(1 HPV, 29 non-HPV); 5 NPC; 15 esophageal cancers; 6 gastric cancers(1 with MSI-H); 2 high grade serous ovary cancer; 1 skin basal cell carcinoma; 1 thymic cancer; 36 HCC; 3 intra-hepatic cholangiocarcinoma; 2 malignant peripheral nerve sheath tumors; 8 urinary tract cancers; 1 RCC; 2 liver neuroendocrine tumors; 1 adrenal carcinoma; 1 breast cancer; 1 mesothelioma; 2 melanoma; 1 primary CNS lymphoma; 1 Papilla of Vater cancer(HER2 amplification and high TMB). The overall clinical benefits were 85%(130/153) and objective response rates were 43%(66/153).Table313PTableCancer typesORRCommentsUrinary tract cancers7/8(87.5%)With Avastin and chemotherapyEsophageal cancer9/15(60%)Afatinib with anti-PD1NSCLC19/32(59%)KN189/IMpower150 in Adeno; CM227 in SCCHNSCC14/30(47%)Afatinib with anti-PD1(easy autoimmune cholestasis and interstitial pneumonitis with pembrolizumab)HCC9/36(25%)With metronomic therapy, Avastin, or chemotherapySCLC1/2(50%)+/-AvastinNPC2/5(40%)Biomarkers neededGC1/6(17%)Responder in MSI-HPapilla of Vater cancer1 stable diseaseHER2 amplification and high TMBSkin cancer1/1High TMBCholangiocarcinoma0/3Combinations searchingRCC1/1With anti-angiogenesis TxPCNSL1/1Rituximab with nivolumab ConclusionsIn one institutional experiences, immunotherapy combinations for refractory advanced cancers have brought encouraging responses and clinical benefits, esp. in urinary tract cancer, esophageal cancers, NSCLC, HNSCC, HCC(the top 5 cancer types endemic in Yun-lin), NPC, skin cancers, primary CNS lymphoma, and cancers with MSI-H or high TMB. Individual combinations, biomarkers, sequencing, and toxicities may be explored in different kinds of advanced cancers to reach favorable outcomes. Legal entity responsible for the studyIRB in National Taiwan University Hospital. FundingHas not received any funding. DisclosureThe author has declared no conflicts of interest.

Oncolytic Newcastle disease virus expressing a checkpoint inhibitor as a radioenhancing agent for murine melanoma.

BackgroundMonoclonal antibodies (mAbs) targeting negative regulators, or checkpoint molecules (e.g. PD1/PD-L1 & CTLA4), of anti-tumoural T cells have demonstrated clinical efficacy in treating several neoplastic diseases. While many patients enjoy remarkable responses to checkpoint inhibitors, a majority show adverse effects. Understanding how checkpoint inhibitors may augment established chemotherapy or radiotherapy regimens or other immunotherapies like oncolytic viruses may lead to better clinical outcomes measured by improved efficacy with reduced toxicity. Here, we assess how Newcastle disease virus (NDV), an oncolytic virus in clinical testing, may interact with radiotherapy to enhance checkpoint inhibitor blockade.MethodsAn immunocompetent B16-F10 murine melanoma model, generally considered to be a poorly immunogenic or “cold” tumour, was utilised to query whether combining localised radiotherapy with NDV may be more effective than either therapy alone in controlling tumours in mice treated with anti-PD1 or anti-CTLA4 monoclonal antibodies. We also investigated whether localised administration of a checkpoint inhibitor through an intratumoural injection of NDV that expresses anti-CTLA4 single-chain variable fragment (scFv) is comparable to systemic administration of anti-CTLA4 when combined with radiation in mediating its anti-tumour efficacy. Response rates were characterised by measuring tumour size over time, observation of complete tumour regression, and overall survival.FindingsOur results show that combining NDV plus radiotherapy with checkpoint inhibitors (PD1 or CTLA4 targeted mAbs) results in significantly better complete tumour regression rates with an abscopal effect in a murine model of melanoma than either single therapy combined with checkpoint inhibitors. Finally, we also show that localised administration of a recombinant NDV expressing anti-CTLA4 plus radiation is comparable to systemic anti-CTLA4 plus radiation in mediating its anti-tumour effect as assayed by survival benefit.InterpretationOur results show that oncolytic NDV plus radiotherapy work together with checkpoint inhibitors to enhance tumour clearance of murine melanoma. NDV is an effective radiotherapy dose-sparing and immunotherapeutic agent capable of transgenic, in vivo expression of an anti-CTLA4 targeted scFv antibody with the potential to spare systemic exposure.FundingThe National Institutes of Health grant HHSN272201400008C supported the work. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.