Clinical activity of fianlimab (REGN3767), a human anti-LAG-3 monoclonal antibody, combined with cemiplimab (anti-PD-1) in patients (pts) with advanced melanoma

9515

Background: Fianlimab and cemiplimab are two high-affinity, fully human, hinge-stabilized IgG4 monoclonal antibodies. In a Phase 1 dose escalation study, fianlimab combined with cemiplimab showed an acceptable safety profile and some clinical activity in pts with advanced malignancies. Here, we present safety and clinical activity data from two expansion cohorts of pts with advanced melanoma (anti–programmed cell death/ligand-1 [anti–PD-(L)1] naïve or experienced) who were treated with fianlimab + cemiplimab and had an opportunity for first on-treatment tumor assessment (cut-off date: Jan 4, 2021). Methods: Pts with advanced melanoma who had no prior anti–PD-(L)1 treatment (naïve) or prior anti–PD-(L)1 treatment within 3 months of screening (experienced) received fianlimab 1600 mg + cemiplimab 350 mg by IV infusion every 3 weeks. Tumor measurements were performed every 6 weeks for the first 24 weeks and subsequently every 9 weeks per RECIST v1.1. Results: 48 pts with advanced melanoma were treated with the combination therapy: 33 were anti–PD-(L)1 naïve and 15 were anti–PD-(L)1 experienced (median age: 69 years vs 59 years; male: 66.7% vs 46.7%; Caucasian: 87.9% vs 60%). The safety profile (including immune-related adverse events [AEs]) of fianlimab + cemiplimab combination therapy was similar to that of anti–PD-1 monotherapy with one exception. The rate of adrenal insufficiency, 8.3% (4/48) of pts, is similar to the rate previously observed with anti–PD-1 + anti–cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) combination therapy but higher than that observed with anti–PD-1 monotherapy. Grade ≥3 treatment-emergent AEs (TEAEs) occurred in 35.4% (17/48) of patients; Grade ≥3 serious TEAEs occurred in 22.9% (11/48) of patients; 8.3% (4/48) of patients discontinued treatment due to a TEAE. The most common TEAEs were fatigue (n = 15, 31.3%) and rash (n = 11, 22.9%). By investigator assessment, objective response rate (includes unconfirmed complete [CR] and partial responses [PR]) was 63.6% (3 CRs and 18 PRs) for anti–PD-(L)1 naïve pts and 13.3% (1 CR and 1 PR) for anti–PD-(L)1 experienced pts. Median progression-free survival and median duration of response for the anti–PD-(L)1 treatment naïve cohort have not been reached. Prognostic clinical markers and tumor biomarkers such as expression of LAG-3, PD-L1, and major histocompatibility complex II are being evaluated. Recruitment is ongoing. Conclusions: The safety profile of fianlimab + cemiplimab is similar to that observed with cemiplimab monotherapy and other anti–PD-1s, with the exception of higher rate of adrenal insufficiency. Fianlimab + cemiplimab combination has shown clinical activity for pts with advanced melanoma that is similar to anti–PD-1 + CTLA-4 combination therapy, but with lower demonstrated rates of TEAEs. Clinical trial information: NCT03005782.

First-in-human study of REGN3767 (R3767), a human LAG-3 monoclonal antibody (mAb), ± cemiplimab in patients (pts) with advanced malignancies

2508

Background: We present initial safety, pharmacokinetics (PK), and efficacy from the dose escalation study of R3767, alone (mono) or in combination with cemiplimab (REGN2810), a PD-1 mAb (combo), in pts with advanced malignancies (NCT03005782). Methods: Pts who had progressed on prior therapy(ies) and/or for whom no therapy with clinical benefit was available were enrolled; most pts had received no prior anti-PD-1/PD-L1. Pts received R3767 1, 3, 10, or 20 mg/kg every 3 weeks (Q3W) ± cemiplimab 3 mg/kg or 350 mg Q3W IV for ≤51 weeks. Crossover from mono to combo was allowed at progression. R3767 PK were evaluated. Tumor measurements were performed Q6W for the first 24 weeks and subsequently Q9W. Data cut-off date was Aug 25, 2018. Results: Mono: 27 pts (median age: 66 yr; ECOG PS: 0 [n=4], 1 [n=23]) were treated. There were no dose-limiting toxicities (DLTs). The most common treatment-emergent adverse event (TEAE) was nausea (22.2%). Grade ≥3 immune-related adverse events (irAEs) of increased alanine and aspartate aminotransferases (each 3.7%) were reported. By investigator-assessment (per RECIST 1.1; INV), best response was stable disease in 11 pts. Combo: 42 pts (median age: 60 yr; ECOG PS: 0 [n=15], 1 [n=27]) were treated. One pt treated with R3767 3 mg/kg Q3W + cemiplimab 3 mg/kg Q3W experienced DLT of grade 4 elevated blood creatine phosphokinase, associated with grade 3 myasthenia syndrome and grade 1 elevated troponin. The most common TEAEs were fatigue (33.3%) and nausea (21.4%). Grade 3 irAE of hypothyroidism (2.4%) was also reported. By INV, 2 (both small cell lung cancer) combo pts and 2 (endometrial cancer and cutaneous squamous cell carcinoma) of 12 additional pts who crossed over from mono to combo had partial responses. PK: R3767 concentrations in serum increased in a dose-dependent manner and were unaffected by combo. Conclusions: The safety profile of R3767 ± cemiplimab was generally tolerable; PK was linear. Early efficacy signals were detected despite the difficult-to-treat pt population. Biomarker studies are ongoing. R3767 20 mg/kg or 1600 mg fixed dose equivalent Q3W as mono and combo were selected for further evaluation. Clinical trial information: NCT03005782.

A study of REGN3767, an anti-LAG-3 antibody, alone and in combination with cemiplimab (REGN2810), an anti-PD1 antibody in advanced cancers

TPS41

Background: Lymphocyte activation gene 3 (LAG-3) is an immune checkpoint receptor with a biological role in T-cell regulation. Analysis of immune-cell infiltrates from human tumors show that a subset of CD4+ and/or CD8+ cells co-express LAG-3 and PD-1 and may be associated with decreased T-cell effector function and tumor escape (Baitsch, 2011; Jie, 2013). Preclinical models provide evidence that dual inhibition of LAG-3 and PD-1 blockade offer synergistic anti-tumor effects and suggest a promising immunotherapy combination that warrants clinical investigation (Woo, 2012). This first in human study will evaluate the safety and efficacy of REGN3767 alone and in combination with cemiplimab in advanced malignancies. Methods: Phase 1 study enrolling patients with advanced malignancies. Dose escalation phase employs a modified 3+3 (4+3) design to assess the tolerability and pharmacokinetics (PK) of REGN3767 monotherapy and in combination with cemiplimab. Monotherapy and combination therapy are exploring multiple escalating REGN3767 dose levels. After tolerability and PK evaluation, doses of REGN3767 will be selected for monotherapy and combination therapy tumor-specific expansion cohorts. Solid tumor expansion cohorts will enroll per Simon’s two-stage design to evaluate safety and preliminary efficacy. Lymphoma expansion cohorts will enroll 15 patients. Patients who are anti-PD-1/PD-L1 therapy naïve and experienced are eligible for separate cohorts. Patients previously exposed to anti-LAG-3 therapy are not eligible. The primary objectives are the determination of the recommended dose for expansion (dose escalation) and ORR (dose expansion). Secondary objectives include characterization of PK and immunogenicity in all patients, as well as anti-tumor efficacy in dose escalation, and safety in dose expansion. This trial is actively enrolling eligible patients in the US, UK, Ireland, and South Korea. 1. Baitsch L et al. J Clin Investig. 2011;121:2350–2360. 2. Jie HB et al. Br J Cancer. 2013;109:2629–2635. 3. Woo SR et al. Cancer Res. 2012;72(4): 917–927. Clinical trial information: NCT03005782.

Phase I study of cemiplimab, a human monoclonal antibody to programmed death (PD)-1, in Japanese patients (pts) with advanced malignancies: Results from the dose exploration

33

Background: Cemiplimab (REGN2810), a high-affinity, highly potent, human monoclonal antibody to PD-1, has demonstrated a safety profile comparable with that of other anti-PD-1 antibodies and antitumor activity in various solid tumors including cutaneous squamous cell carcinoma and non-small-cell lung cancer (NSCLC) in pts outside of Japan. We present analysis of Part 1 of a two-part, multicenter, open-label, Phase 1 study of cemiplimab in Japanese pts with advanced malignancies. Methods: Part 1 dose exploration pts received either cemiplimab 250 mg (n=6) or 350 mg (n=7) Q3W IV for up to 108 weeks. Tumor measurements were performed every 9 weeks according to RECIST 1.1. Data cut-off date was July 13, 2018. Results: Thirteen pts were enrolled: median age, 62 years (range: 33–75); 8 F. Twelve (92.3%) and 7 (53.8%) pts had received prior cancer-related systemic therapy and radiotherapy, respectively. Median duration of cemiplimab exposure was 13.1 weeks (range: 3.0–54.6). At the data cut-off date Part 1 was fully enrolled and 9 pts (69.2%) had discontinued treatment, primarily due to disease progression (n=7, 53.8%). The most common treatment-emergent adverse events (TEAEs) of any grade were contact dermatitis, rash, and viral upper respiratory tract infection, each occurring in 3 pts (23.1%). The following grade ≥3 TEAEs occurred in 1 pt (7.7%): hypophosphatemia, hyponatremia, autoimmune colitis, and dehydration; the last two events occurred in the same pt. No dose-limiting toxicities were reported. Cemiplimab serum concentrations were as expected from the reported PK characteristics of cemiplimab. Objective response rate (ORR; complete response + partial response [PR]) and disease control rate (ORR + stable disease [SD]) were 23.1% (3 PR) and 53.8% (7/13; 4 SD), respectively. Conclusions: Cemiplimab exhibited substantial antitumor activity in Japanese pts with advanced malignancies. Cemiplimab 350 mg Q3W dosing regimen was selected for the expansion studies. The safety profile was comparable with those previously reported for cemiplimab and other anti-PD-1 agents. Part 2 is open and enrolling pts with NSCLC in Japan. Clinical trial information: NCT02760498.

Potential predictive and prognostic biomarkers identified in baseline plasma samples from the VELOUR trial

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Background: Biomarkers of resistance or susceptibility to vascular endothelial growth factor (VEGF) inhibition have not been validated. Ziv-aflibercept (ZALTRAP), a fusion protein that binds and neutralizes ligands of VEGFR1 and VEGFR2 (e.g., VEGFA, PLGF, and VEGFB), is approved for the treatment of metastatic colorectal cancer (mCRC) in combination with FOLFIRI in patients who have progressed after oxaliplatin therapy. We are currently analyzing plasma samples from VELOUR, the registration trial of FOLFIRI +/- ziv-aflibercept, in an effort to identify prognostic and predictive factors. Methods: VELOUR was a prospective, multicenter, multinational, randomized (1:1), double-blind, parallel-arm phase III study conducted in 1,226 patients. Retrospective analysis of circulating proteins from 553 baseline plasma samples was performed. Samples were analyzed for levels of 98 analytes using multiplex assays and ELISA. Biomarker values were dichotomized around the median value and analyzed with respect to overall survival (OS). Results: The biomarker study sub-population was similar to the overall VELOUR population. For OS, the hazard ratio (HR) was 0.809 in the plasma biomarker population vs. HR =0.817 in the overall VELOUR population. For PFS, the HR = 0.752 in the plasma biomarker population vs. HR = 0.758 in VELOUR. Patient demographics, including ECOG status, were similar between the groups. Several biomarkers were identified as potentially predictive or prognostic (or both) of OS, with a HR<0.7 (false discovery rate of 0.05 and interaction p < 0.10). No biomarker subset corresponded to worse OS with ziv-aflibercept treatment. Conclusions: Multiple potential prognostic and predictive biomarkers were identified in VELOUR and will be presented. These results are exploratory and require prospective studies for validation. Patient subsets with elevated expression of alternative angiogenic factors or increased pro-inflammatory markers may correlate with poor outcome overall, and in some cases are not improved by addition of ziv-aflibercept treatment. Further investigation of this dataset continues, including analysis of on-treatment plasma samples in a subset of patients.

CX3CR1+ interstitial dendritic cells form a contiguous network throughout the entire kidney

Dendritic cells (DCs) interface innate and adaptive immunity in nonlymphoid organs; however, the exact distribution and types of DC within the kidney are not known. We utilized CX3CR1GFP/+ mice to characterize the anatomy and phenotype of tissue-resident CX3CR1+ DCs within normal kidney. Laser-scanning confocal microscopy revealed an extensive, contiguous network of stellate-shaped CX3CR1+ DCs throughout the interstitial and mesangial spaces of the entire kidney. Intravital microscopy of the superficial cortex showed stationary interstitial CX3CR1+ DCs that continually probe the surrounding tissue environment through dendrite extensions. Flow cytometry of renal CX3CR1+ DCs showed significant coexpression of CD11c and F4/80, high major histocompatibility complex class II and FcR expression, and immature costimulatory but competent phagocytic ability indicative of tissue-resident, immature DCs ready to respond to environment cues. Thus, within the renal parenchyma, there exists little immunological privilege from the surveillance provided by renal CX3CR1+ DCs, a major constituent of the heterogeneous mononuclear phagocyte system populating normal kidney.

The role of the class II transactivator (CIITA) in MHC class I and II regulation and graft rejection in kidney

Class II transactivator (CIITA) induces transcription of MHC class II genes, and induces class I in some cell lines. We examined the effect of CIITA deficiency on class I and II expression in mouse kidney. In CIITA knockout (CIITAKO) mice, basal class II was absent, but class I levels were mildly but significantly increased. Allogeneic stimulation or ischemic injury increased class I and II expression in kidneys of control (wild-type, WT) mice but induced only class I in CIITAKO mice. Thus, in kidney, all basal and induced class II expression was CIITA-dependent, but neither basal nor induced class I was CIITA-dependent. Rejecting kidney allografts from CIITAKO mice in CBA hosts manifested intense induction of donor class I but no donor class II expression. Rejecting kidneys from both WT and CIITAKO donors showed predominantly CD8 T-cell infiltration at days 7 and 21, with increasing tubulitis and arteritis at day 21. CIITAKO kidneys showed fewer infiltrating cells than WT kidneys at day 21. Thus CIITA-deficient kidneys have no basal and induced class II expression but display intense induction of class I expression, and evoke typical rejection lesions, although some indices of infiltration are reduced at day 21.

The immunological synapse

The adaptive immune response is initiated by the interaction of T cell antigen receptors with major histocompatibility complex molecule-peptide complexes in the nanometer scale gap between a T cell and an antigen-presenting cell, referred to as an immunological synapse. In this review we focus on the concept of immunological synapse formation as it relates to membrane structure, T cell polarity, signaling pathways, and the antigen-presenting cell. Membrane domains provide an organizational principle for compartmentalization within the immunological synapse. T cell polarization by chemokines increases T cell sensitivity to antigen. The current model is that signaling and formation of the immunological synapse are tightly interwoven in mature T cells. We also extend this model to natural killer cell activation, where the inhibitory NK synapse provides a striking example in which inhibition of signaling leaves the synapse in its nascent, inverted state. The APC may also play an active role in immunological synapse formation, particularly for activation of naïve T cells.

In vivo class II transactivator expression in mice is induced by a non-interferon-gamma mechanism in response to local injury

BACKGROUND

Tissue injury induces MHC class II expression, which could be important in the recognition of that tissue as an allograft. The class II transcriptional activator (CIITA) is the major regulator of basal and induced MHC class II expression and is essential for antigen presentation. The role of CIITA in the induction of class II by tissue injury is unknown. In this study, we examined CIITA induction in the course of acute ischemic or toxic renal injury in mice, including the role of interferon (IFN)-gamma and of the transcription factor, interferon regulatory factor (IRF)-1.

METHODS

Kidneys were injured by ischemia or by gentamicin toxicity and were then studied for changes in gene expression using Northern blot, reverse transcriptase-polymerase chain reaction, radioimmunoassay, and tissue staining. We compared wild-type (WT) mice to IFN-gamma knockout (GKO) or IRF-1 knockout mice.

RESULTS

Ischemic injury induced CIITA and class II expression in the kidney, in WT and GKO mice. Gentamicin injury also induced both CIITA and class II expression, independent of IFN-gamma, in WT and GKO mice. After ischemic injury, the induction of class II protein levels and CIITA and class II mRNA levels were induced, to a lesser degree, in IRF-1 knockout mice.

CONCLUSIONS

These data indicate that CIITA is induced by tissue injury, and probably accounts for class II induction during tissue injury. CIITA induction by injury is largely IFN-gamma independent but requires IRF-1. The similarities of the pattern of CIITA and class II induction in ischemic and toxic injury suggest that this is a stereotyped response of injured tissue and not a consequence of a particular mechanism of injury.

Assessment of ST segment depression in patients with cardiac disease after local anesthesia

This study found that dental treatment with 2% lidocaine with 1:100,000 epinephrine did not provoke myocardial ischemia, as assessed by greater than or equal to 1 mm of ST segment depression. Although in some cases systolic and diastolic blood pressure and rate pressure product increased slightly after local anesthetic administration, these changes were not statistically significant. Because these patients were medically supervised and compliant with cardiac therapy, this study suggests that such patients are not at great risk while receiving local anesthesia with 1:100,000 epinephrine for routine dental care.

Assessment of stress during periodontal surgery with intravenous sedation and with local anesthesia only

Ten patients with moderate to advanced periodontal disease were subjected to two similar periodontal surgical procedures. Each patient received either intravenous conscious sedation with local anesthesia or local anesthesia only. The stress-reducing effects of a conscious sedation regimen consisting of pentobarbital, meperidine, and diazepam were evaluated in these patients. Stress was evaluated by monitoring changes in serum cortisol, human growth hormone, and vital signs. Blood samples were obtained at 15- to 30-minute intervals throughout each procedure and were evaluated for serum cortisol and growth hormone. The conscious sedation group had significantly lower serum cortisol levels and lower systolic blood pressure, indicating that the patients having periodontal surgery with conscious sedation experienced reduced stress. Physiologic stability was maintained for each patient, indicating that this conscious sedation regimen can be used to reduce measurable parameters of stress that patients develop during periodontal surgery.

Value of antibiotic prophylaxis in periodontal surgery

THE MORBIDITY and incidence of bacteremia in periodontal surgery with or without cephalexin prophylaxis were assessed in adults on the basis of clinical evaluations and blood cultures. Cephalexin reduced the incidence of polymicrobic bacteremias. There was no correlation between objective signs of tissue healing and antibiotic coverage in treated or nontreated patients. In vitro antibiotic susceptibility data showed that cephalexin was active against the aerobic and anaerobic bacteria isolated from blood specimens taken during surgery.

Clinical and antimicrobial effect of stannous fluoride on periodontitis

The antimicrobial effect of stannous fluoride (SnF2) on suspected pathogenic morphotypes of bacterial plaque in chronic periodontal disease was assessed. Alterations in morphological groups of subgingival and supragingival plaque bacteria from three diseased sites and one periodontally healthy site were determined by darkfield microscopy in 10 male patients with advanced periodontitis. In addition, clinical indices were also measured. The three diseased sites received either 1.64% SnF2, 0.4% SnF2 or sterile saline by subgingival irrigation. The healthy site received sterile saline only. The patients were seen weekly over a 10-week period and at each appointment bacterial sampling and clinical indices were measured. Results indicated that 1.64% SnF2 caused a dramatic and sustained decrease of subgingival motile bacteria and spirochetes following irrigation. By the sixth week these bacteria returned to 50% of their original concentration. Bleeding index scores, which were significantly reduced, correlated positively to the reduction in motile bacteria and spirochetes. Sites irrigated with 0.4% SnF2 also demonstrated a similar pattern of reduction of motile bacteria and spirochetes but without their total elimination and a more rapid return to original levels. In the diseased sites receiving sterile saline there was a decrease in motile bacteria and spirochetes, corresponding with saline irrigation, which rapidly returned to baseline levels. The healthy control sites were unchanged. Supragingival plaque index scores did not correlate with the bleeding index, motile bacteria and spirochetes, or with subgingival irrigation.