Immunother Cancer Research Articles

DELTA-1: A global, multicenter, phase 2 study of ITIL-168, an unrestricted autologous tumor-infiltrating lymphocyte (TIL) cell therapy, in adult patients with advanced cutaneous melanoma.

TPS9594 Background: Patients (pts) with advanced (unresectable or metastatic) cutaneous melanoma and persistent disease after checkpoint inhibitor therapy have poor outcomes and limited treatment options, highlighting a significant unmet medical need (Schadendorf D et al. Lancet. 2018;392:971-984). Investigational autologous TIL cell therapies have shown promise in this population, partly attributable to their intrinsic and patient-specific antitumor activity (Borch TH et al. J Immunother Cancer. 2020;8:e000668). Made from each patient’s digested and cryopreserved tumor, ITIL-168 is an autologous TIL cell therapy manufactured to offer an unrestricted T-cell receptor repertoire. A single-center, compassionate use clinical series demonstrated the feasibility and clinical utility of an earlier version of ITIL-168, with a high overall response rate among pts previously treated with PD-1 inhibitor (PD-1i) therapy (58%, n = 12; Pillai M et al. Ann Oncol. 2021;32[suppl 5]:S882). DELTA-1 (NCT05050006) is a global, multicenter phase 2 study to evaluate efficacy and safety of ITIL-168 in pts with cutaneous melanoma relapsed or refractory to a PD-1i, pts intolerant to a PD-1i, and pts whose current best response to a PD-1i is stable disease. Methods: Pts aged ≥18 years with histologically confirmed advanced cutaneous melanoma, ECOG performance status 0-1, and adequate organ function will be enrolled in 1 of 3 cohorts. Cohort 1 (n≈80) will include pts who relapsed after or were refractory to ≥1 prior line of systemic therapy, including a PD-1i and, if BRAF-mutated, a BRAFi ± MEKi. Cohorts 2 and 3 (n≈25 each) will include pts intolerant to PD-1i and those with stable disease after ≥4 doses of PD-1i, respectively. After tumor resection for TIL harvest, pts must have ≥1 remaining measurable lesion per RECIST 1.1. Pts with uveal, acral, or mucosal melanoma, prior allogeneic transplant or cell therapy, and with central nervous system (CNS) disorder or symptomatic and/or untreated CNS metastases are ineligible. Pts will receive 5 days of lymphodepleting chemotherapy (cyclophosphamide ×2 days overlapping with fludarabine ×5 days) followed by a single ITIL-168 infusion (≥5×109 cells) and supportive short-course, high-dose IL-2. The primary endpoint is objective response rate (ORR) per central review. Secondary endpoints include duration of response, progression-free survival, overall survival, disease control rate, TIL persistence, and safety. Hypothesis testing of ORR will be performed for cohort 1. The primary analysis will occur when all pts in the cohort 1 modified intent-to-treat population have been followed for ≥6 months after the first posttreatment disease assessment. DELTA-1 opened for enrollment in September 2021. Updated site information will be given at the time of presentation. Clinical trial information: NCT05050006.

Davoceticept (ALPN-202), a PD-L1-dependent CD28 costimulator and dual checkpoint inhibitor, in combination with pembrolizumab in patients with advanced malignancies (NEON-2).

TPS2683 Background: Despite successes with checkpoint inhibition (CPI) in a wide range of tumors, most demonstrate primary or acquired resistance, warranting better therapeutic strategies. PD-1 is now recognized to effect much of its benefit by disinhibiting CD28 signaling – a mechanism expected to require intra-tumoral engagement of CD28 by its ligands CD80/CD86. Davoceticept (ALPN-202), a variant CD80 vIgD-Fc fusion protein, was engineered to provide tumor localizing PD-L1-dependent CD28 agonism, while inhibiting PD-L1 and CTLA-4. Davoceticept has demonstrated superiority to CPI-only therapies in both in vitro and in vivo tumor models, while also demonstrating additional benefit in combination with targeted PD-1 axis blockade (Lewis et al. (2019) J Immunother Cancer 7(S1): P467). The benefit appeared at least additive in models of poorly immunogenic tumors, suggesting the possibility of meaningful clinical benefit where CPI therapeutic efficacy is limited, such as noninflamed tumors. Single agent safety and tolerability of davoceticept has been demonstrated along with pharmacodynamic evidence of CD28 engagement with immune checkpoint inhibition (Moser et al. (2021) J Clin Oncol 39(s15): 2547). Methods: NEON-2 is an open-label dose escalation and expansion study of davoceticept combined with pembrolizumab in adults with advanced solid tumors or lymphoma that was initiated in June 2021 (NCT04920383). Eligibility includes tumors where single agent PD-(L)1 antagonists are SOC, are refractory or resistant to standard therapies (including approved CPIs), or have no standard or curative therapy. The study employs a standard 3+3 dose escalation design with two schedules, Q1W and Q3W of davoceticept. Pembrolizumab is given per label at 400 mg IV Q6W. Objectives include evaluation of safety and tolerability, identification of the recommended phase 2 dose(s) (RP2D), PK, PD, exploratory predictive biomarker analysis (i.e., PD-L1, CD28, CD80 and CD86 expression, as well as immunophenotyping of immune cell populations on treatment) and preliminary anticancer activity of davoceticept in combination with pembrolizumab. Disease assessments are evaluated by RECIST v1.1 for solid tumors or by Lugano Classification for lymphoma. Efficacy endpoints include ORR, duration of response and disease control rate. Once the RP2D combination is identified, tumor-specific expansion cohorts of ̃ 30- 35 patients will be performed, including histologies that have not been demonstrated to be CPI responsive, as well as those where CPIs are approved SOC. The 0.1 mg/kg cohorts have been completed without DLT. Enrollment to the 0.3 mg/kg cohorts began in September 2021. Clinical trial information: NCT04920383.

Phase 2 trial of enoblituzumab plus retifanlimab or tebotelimab in first-line treatment of patients (pts) with recurrent or metastatic squamous cell carcinoma of the head and neck (R/M SCCHN).

TPS6102 Background: Head and neck cancer accounts for ̃900,000 cases and over 400,000 annual deaths worldwide as of 2021. Pts with R/M SCCHN have a poor prognosis with median overall survival <1 year. Programmed death (PD)-protein 1 (PD-1) and PD-ligand 1 (PD-L1) blockade has shown antitumor activity in advanced SCCHN. Enoblituzumab (MGA271) is an investigational monoclonal antibody (mAb) that binds B7-homolog 3 (B7-H3) with enhanced binding to the activating Fc gamma receptor CD16A, particularly the low-affinity allele CD16A-158. B7-H3 is overexpressed in many cancers, including SCCHN, but not in most normal tissues. Retifanlimab (MGA012, INCMGA00012) is an investigational anti-PD-1 mAb, blocking binding of PD-L1 or PD-ligand 2 (PD-L2) to PD-1. Tebotelimab (MGD013) is an investigational, Fc-bearing bispecific, tetravalent DART® molecule designed to bind PD-1 and lymphocyte activation gene 3, inhibiting their interaction with PD-L1 or PD-L2 and major histocompatibility complex class II. In vitro data suggest that both retifanlimab and tebotelimab have potential to sustain enoblituzumab-mediated immune activation and antitumor activity (Obara G, et al. Ann Oncol. 2021;32[suppl 5]:S814). Combination of enoblituzumab with retifanlimab or tebotelimab sustained the ability of natural killer cells and CD8+ T cells to produce interferon gamma upon restimulation. Both retifanlimab and tebotelimab enhanced enoblituzumab-dependent cytotoxicity targeting B7-H3–expressing tumor cells. In a phase 1/2 study, the combination of enoblituzumab with pembrolizumab was well tolerated (Aggarwal C, et al. J Immunother Cancer. 2022 [under review]). The overall response rate in anti-PD-1/PD-L1–naïve pts with SCCHN (post platinum) was 33% (6/18), including 1 confirmed complete and 5 confirmed partial responses, warranting further development of this combination in R/M SCCHN. Methods: This is an open-label, nonrandomized study in first-line treatment of pts with R/M SCCHN. Approximately 50 pts with PD-L1 combined positive score (CPS) ≥1 will receive enoblituzumab 15 mg/kg plus retifanlimab 375 mg and 30 pts with CPS <1 will receive enoblituzumab 15 mg/kg plus tebotelimab 600 mg. Dosing is once every 3 weeks with tumor assessment at the end of Cycle 2 and every 3 cycles thereafter. Pts with no prior systemic therapy for R/M SCCHN are eligible. Pts who completed systemic therapy >6 months before the study, if given as part of multimodal treatment for locally advanced disease, are eligible. In the tebotelimab cohort, safety data will be reviewed for dose-limiting toxicities through Cycle 2 Day 7 on the first 12 pts (2 mini cohorts of 6 pts each). All pts will be followed for survival after the last dose of study drug. The first pt was enrolled in March 2021, and 28 pts are on treatment as of January 19, 2022. Clinical trial information: NCT04634825.

Pembrolizumab (pembro) plus dabrafenib (dab) and trametinib (tram) in BRAFV600E/K-mutant melanoma: Long-term follow-up of KEYNOTE-022 parts 1, 2, and 3.

9516 Background: KEYNOTE-022 (NCT02130466) was a phase 1/2 study of pembro + dab + tram or pembro + tram in patients (pts) with unresectable stage III/IV melanoma (parts 1-3) or solid tumors (parts 4 and 5). In previous analyses of pts with BRAFV600E/K -mutant melanoma, pembro + dab + tram was shown to have manageable safety in parts 1-3, albeit with a higher incidence of TRAEs in part 3, and substantially improved PFS, DOR, and OS vs placebo + dab + tram in part 3, although the primary end point of a statistically significant improvement in PFS was not met. Long-term follow-up of pts with BRAFV600E/K-mutant melanoma in parts 1-3 are presented. Methods: Eligible pts were ≥18 y with unresectable stage III/IV BRAFV600E/K-mutant melanoma, ≥1 measurable lesion per RECIST v1.1, ECOG PS 0/1, and no prior systemic therapy for advanced disease. In parts 1 and 2, which involved dose finding and confirmation, pts received pembro 2 mg/kg IV Q3W + dab 150 mg PO BID + tram 2 mg PO QD (MTD). In part 3, pts were randomized 1:1 to pembro + dab + tram at MTD or placebo + dab + tram. Primary end points were safety, tolerability, and MTD (parts 1 and 2); ORR per RECIST v1.1 by investigator review (part 2); and PFS per RECIST v1.1 by investigator review (part 3). Data cutoff was July 14, 2021. Results: Median (range) study follow-up was 72.9 mo (68.4-84.5) in parts 1 and 2 (n = 15) and 61.2 mo (50.7-67.5) for all pts (n = 120; 60 each arm) in part 3. Safety of pembro + dab + tram in parts 1 and 2 was consistent with prior reports; grade 3/4 TRAEs occurred in 11 pts (73%), and no additional DLTs occurred. ORR in parts 1 and 2 was 67% (95% CI, 38-88), which was similar to that reported at an earlier data cut (73% [95% CI, 45-92]); median DOR was 19.4 mo (95% CI, 2.8-NR), median OS was NR (95% CI, 10.3-NR), 48-mo OS rate was 60%, median PFS was 15.2 mo (95% CI, 4.2-NR), and 48-mo PFS rate was 28% (Ribas A et al. Nat Med. 2019;25:936-940). In part 3, median PFS was 17.0 mo (95% CI, 11.3-NR) for pembro + dab + tram vs 9.9 mo (95% CI, 6.7-15.6) for placebo + dab + tram (HR, 0.46; 95% CI, 0.29-0.74) and 24-mo PFS rate was 47% vs 16%, and median OS was 46.3 mo (95% CI, 23.9-NR) vs 26.3 mo (95% CI, 18.2-38.6); and 24-mo OS rate was 63% vs 52%, respectively. ORR was 65% (95% CI, 52-77) for pembro + dab + tram vs 72% (95% CI, 59-83) for placebo + dab + tram; median DOR was 30.2 mo (95% CI, 14.1-NR) vs 12.1 mo (95% CI, 6.0-15.7). Safety in part 3 was similar to prior reports; grade 3-5 TRAEs occurred in 42 pts (70%) in the pembro + dab + tram arm vs 27 pts (45%) in the placebo + dab + tram arm (Ferrucci PF et al. J Immunother Cancer. 2020;8:e001806). No additional grade 5 TRAEs occurred (1 grade 5 pneumonitis had occurred at prior analysis). Conclusions: At long-term follow-up, first-line pembro + dab + tram continued to show improved PFS, DOR, and OS compared with placebo + dab + tram in pts with BRAFV600E/K-mutant melanoma. TRAEs were more common with pembro + dab + tram but no new safety signals were identified. Clinical trial information: NCT02130466.

Pathologic response after induction chemo-immunotherapy with single or double immune checkpoint inhibition in locally advanced head and neck squamous cell carcinoma (HNSCC): Expansion cohorts of the CheckRad-CD8 trial.

6064 Background: Targeting the immune checkpoint CTLA-4 in addition to PD-1/PD-L1 alone did not increase efficacy in HNSCC, whereas this has not been studied in combination with chemotherapy. Induction chemo-immunotherapy followed by pathologic response-based patient selection for chemotherapy-free radioimmunotherapy was efficient in locally advanced HNSCC (J Immunother Cancer. 2022 Jan;10(1):e003747). The expansion cohorts of the CheckRad-CD8 trial studied safety and efficacy of induction chemo-immunotherapy with increased dose or without CTLA-4 inhibition. Methods: Patients with previously untreated stage III-IVB (AJCC 8th edition) HNSCC were eligible for this multicenter phase II trial. Induction chemo-immunotherapy of the main cohort (MC) consisted of a single cycle of cisplatin 30mg/m² d1-3, docetaxel 75mg/m² d1, durvalumab 1500mg fix dose d5 and tremelimumab 75mg fix dose d5. Patients in expansion cohort 1 (EC1) received this combination with high dose tremelimumab 300mg fix dose d5 and patients in expansion cohort 2 (EC2) received no tremelimumab. In EC1 and EC2 prophylactic G-CSF was recommended. Patients with at least 20% increase of intratumoral CD8+ immune cell density or pathological complete response (pCR) in the re-biopsy entered chemotherapy-free radioimmunotherapy up to a total dose of 70Gy. The current analysis focuses on toxicity and pathologic response after induction chemo-immunotherapy. Results: Between Sep 2018 and Sep 2021, 80 patients were enrolled in the MC (one excluded), 20 in EC1 and 20 in EC2 (one excluded) subsequently. In the MC, EC1 and EC2 a total of 56%, 50%, 58% were stage IV and 29%, 30%, 26% had p16 positive oropharyngeal tumors. Baseline median intratumoral CD8+ immune cell density was 395/mm², 505/mm² and 763/mm² in MC, EC1 and EC2. After induction chemo-immunotherapy 41 (52%), 12 (60%) and 11 (58%) of the patients had pCR in the re-biopsy in MC, EC1 and EC2. Patients with residual tumor after induction therapy had a median intratumoral CD8+ immune cell density of 670/mm², 781/mm² and 1605/mm², which was a median increase by factor 3.0, 2.1 and 4.8 in the corresponding patients’ tissue samples. In the cohorts MC, EC1 and EC2 the overall rate of grade 3-4 adverse events per patient was 1.38, 1.35 and 0.58. The corresponding rate of non-hematologic adverse events per patient was 0.84, 0.95 and 0.37, respectively. Conclusions: Neither increase of tremelimumab dosage nor its omission did significantly affect pathologic response to induction chemo-immunotherapy with cisplatin/ docetaxel/ durvalumab. Non-hematologic toxicity was slightly increased for high dose tremelimumab and clearly decreased without tremelimumab. The role of concomitant administration of tremelimumab with radiotherapy cannot be assessed until the final study analysis. Clinical trial information: NCT03426657.

A phase 1 study of CD38-bispecific antibody (XmAb18968) for patients with CD38 expressing relapsed/refractory acute myeloid leukemia and T-cell acute lymphoblastic leukemia.

TPS7070 Background: Outcomes of adults with relapsed/refractory T-cell acute lymphoblastic leukemia (T-ALL) and acute myeloid leukemia (AML) have remained poor. CD38 is a transmembrane glycoprotein with several important functions including its role in immune escape of tumor cells [Chillemi A et al. Front Immunol 2017, Furano A et al. J Immunol 1990]. Several studies have demonstrated that CD38 is expressed in T-ALL and AML and is targetable with CD38 blocking agents [Naik J et al. Haematologica 2019, Bride KL et al. Blood 2018, Tembhare et al. J Immunother Cancer 2020]. XmAb18968 is a novel CD38-CD3 bi-specific T-cell engager with Fc domain modified to minimize Fcγ receptor binding and non-selective T-cell activation resulting in reduced cytokine release without compromising target cell killing. We hypothesize that targeting CD38 in relapsed/refractory T-ALL and AML would be safe and feasible using XmAb18968. Methods: This is an investigator-sponsored multi-institutional phase I study evaluating the safety and tolerability of XmAb18968. Patients aged 18 years or above with relapsed/refractory T-ALL or AML (including measurable residual disease relapse), CD38 expression ≥ 20% by flow cytometry, and adequate organ function will be eligible. Major exclusion criteria are hematopoietic cell transplantation within 6 months of enrollment, active acute graft-versus-host disease, and acute promyelocytic leukemia. The primary objective is to determine the recommended phase 2 dose (RP2D) and toxicity profile of XmAb18968. The secondary objectives include determination of response rates, duration of response, survival and pharmacokinetics. Exploratory objectives include correlation of responses with genomic profile, characterizing changes in serum cytokines and phenotypic expression of activated T-cells and leukemic cells, correlation of the phenotypic expression with changes in the transcriptome at the single-cell level, proteomics evaluation of cytokine secretion at the single-cell level and correlation of response with N-glycan profiling, quantitative site-occupancy and direct glycopeptide analysis. The study will follow 3+3 design. Dose escalation will proceed in two separate groups: Group A for subjects with T-ALL and Group B for subjects with AML. Patients will be entered sequentially to each dose level [0.8mg cohort, 1mg cohort, 1.3mg cohort, 1.5mg cohort). The observation period for dose-escalation will be 28-days. RP2D will be defined as the highest dose level at which none of the 3 treated subjects, or no more than 1 of the 6 treated subjects’ experiences a dose limiting toxicity. A minimum of 24 and a maximum of 60 patients will be enrolled. The study is being conducted at 6 sites in United States and is currently open for enrollment. Clinical trial information: NCT05038644.

Circulating tumor DNA as a predictive biomarker in Merkel cell carcinoma

Circulating tumor DNA as a predictive biomarker in Merkel cell carcinoma

Abstract P046: NKG2A and HLA-E define a novel alternative immune checkpoint axis in bladder cancer

Abstract Background: Bladder cancer is characterized by a poor prognosis, with muscle-invasive cases harboring a 34-76% 10-year recurrence-free survival rate [1]. Neoadjuvant PD-1/PD-L1 blockade strategies have recently been approved by the US Food and Drug Administration for bladder cancer treatment, yet only achieving a complete response rate of 31-37%, thereby suggesting additional mechanisms of resistance [2]. HLA-E is a known inhibitor of NKG2A+ CD8 T cells and NK cell responses. A monoclonal antibody binding to the NKG2A receptor has been developed and proven to restore CD8 T cell and NK cell responses in head and neck cancer, with ongoing clinical trials across multiple tumor indications [3,4]. We evaluated the potential role of the HLA-E/NKG2A inhibitory pathway in modulating T cell immunity in bladder cancer. Methods: CyTOF was performed on CD8+ T cells from fresh bladder tumors (n=6), as well as on expanded CD8+ T cells from bladder-draining lymph nodes (n=11) and tumors (n=8). Flow cytometry (n=25) and single-cell RNA-sequencing (scRNAseq) (n=13) were performed on cells from fresh bladder tumors. Results: Mechanisms of tumor escape from CD8+ T cell recognition include impairment of antigen presentation. Accordingly, we found a significant reduction of HLA class I expression on tumors. However, expression of DNAM-1-activating ligands (e.g. CD112,CD155) on bladder tumors was retained, indicating a possible role for TCR-independent activation pathways traditionally ascribed to natural killer (NK) cells. Using mass cytometry and scRNAseq, we observed that acquisition of NKG2A on tumor-derived PD-1+ CD8+ T cells promotes tissue-resident memory features alongside diminished CD28 expression and significantly weaker sensitivity to CD3/CD28-signaling. However, NKG2A+ CD8 T cells possess a proliferative advantage with enhanced expression of DNAM-1 and cytolytic machinery. Strikingly, we found that NKG2A+PD-1+ CD8 T cells are strongly activated in response to HLA class I-deficient tumors compared to their NKG2A− PD-1+ CD8 T cell counterparts. TCR-independent NK-like function by NKG2A+ CD8 T cell is partly mediated by the DNAM-1 pathway and inhibited by HLA-E. NKG2A+ CD8 T cell functions are restored upon NKG2A blockade, where efficiency positively correlates with HLA-E expression on bladder tumors. Discussion: Collectively, our data indicate that NKG2A+ CD8 T cells display a strong capacity for TCR-independent activation that enables them to circumvent bladder tumor evasion mechanisms. NKG2A+ CD8 T cells lack expression of CD28 suggesting a lower susceptibility to PD-1-mediated inhibition. Our data suggest a need for thorough reappraisal of current protocols that assess CD8 T cell exhaustion and for strategies to restore their antitumor functions.

T cell fat catabolism: A novel target for kynurenine?

T cell fat catabolism: A novel target for kynurenine?

A Novel Bispecific T Cell Engager (UMG2-BTCE) Targeting CD1a-CD3ε Is Effective Against Cortical-Derived Acute Lymphoblastic Leukemia

Caterina Riillo*and Daniele Caracciolo*equally contributed to the work.Background: T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive and orphan hematological disease derived from malignant transformation of thymic T cell precursors. At present, the prognosis of relapsed/refractory patients remains poor. While immunotherapy has significantly improved the outcome of B cell acute lymphoblastic leukemia (B-ALL), the lack of tumor-restricted T cell antigens hampers its efficacy in T-ALL. (Caracciolo D, Riillo C, et al. Therapeutic afucosylated monoclonal antibody and bispecific T-cell engagers for T-cell acute lymphoblastic leukemia. J Immunother Cancer. 2021) Therefore, the development of novel immune-therapeutics is eagerly awaited.CD1a is a cell surface glycoprotein restricted to cortical T-ALL subtype expressed only by cortical thymocytes and Langerhans's cells among human healthy tissue and might represent a valuable therapeutic target for the treatment of T-ALL. On this basis, we develop an asymmetric monovalent 2 +1 bispecific T cell engager (BTCE) derived from a novel humanized UMG2 mAb directed against an original CD1a epitope selectively expressed by cortical T-ALL cells.Methods.To evaluate if UMG2 recognizes a specific CD1a epitope, HEK293T cell line, negative for CD1a expression, has been transfected with a plasmid encoding for CD1a (HEK293T/CD1a) and with a negative control vector and UMG2 reactivity has been evaluated by flow cytometry. A competitive binding assay between UMG2 and commercially available CD1a antibodies was performed. The UMG2 expression profile was evaluated on healthy donor peripheral blood cells and on a panel of cortical T-ALL cell lines. To develop a UMG2 targeting immunotherapeutic construct with a limited unspecific T cell activation, an asymmetric 2+1 UMG2-CD3 bispecific T cell engager (BTCE) was generated using knobs into holes technology. UMG2-CD3 BTCE in vitro T cell-mediated activity was evaluated on HEK293T CD1a antigen-negative cell line, on HEK293T/CD1a, on patient-derived and T-ALL cell lines, co-cultured with healthy donors derived peripheral blood mononuclear cells (PBMCs), CD4/CD8 depleted and CD56 enriched lymphocytes at 10:1 E:T ratio.T cell activation, degranulation, proliferation, and pro-inflammatory cytokine secretion were assessed by flow cytometry on primary blasts and on T-ALL cells with effector lymphocytes.To evaluate UMG2-CD3 BTCE anti-tumor activity against CD1a expressing T-ALL cell line in vivo, Hu-PBMCs NSG mouse model was generated, and tumor growth was assessed by fluorescent imaging probe.ResultsUMG2 mAb recognizes a previously uncharacterized CD1a epitope and does not compete with any of the commercially available anti-CD1a mAbs. While a strong UMG2 reactivity is observed on both patient-derived samples and T-ALL cells, no binding is found on normal blood cells, indicating the tumor-restricted pattern of reactivity of UMG2.UMG2-CD3 BTCE specifically binds CD1a on leukemic cells and activates CD3ε downstream signaling pathway on T lymphocytes, as demonstrated by the concentration-dependent increase of T cell proliferation, cytotoxic degranulation (CD107a), expression of cell surface activation markers (CD25, CD69), and pro-inflammatory cytokine secretion (IL-2, TNF-α, IFN-γ).UMG2-CD3 BTCE mediates strong and concentration-dependent specific T cell re-directed cytotoxicity only on CD1a expressing leukemic cells in the presence of T lymphocytes. Minimal UMG2-CD3 BTCE residual anti-tumor activity is observed in CD4/CD8 depleted and CD56 enriched lymphocytes, while CD56 depleted and Fc-blocked PBMCs are able to induce an anti-T-ALL activity comparable to total PBMCs, demonstrating that UMG2-BTCE could not recruit monocytes and NK cells through Fc-FcyR interaction by reducing the risk of immune-mediated adverse events. Most importantly, in an in vivo of immune-humanized NSG mice engrafted with human T-ALL cells, UMG2-BTCE significantly inhibits tumor growth translating into the survival advantage of treated animals.Conclusion: Taken together, all these results provide a framework for the clinical development of UMG2-CD3 BTCE potentially offering a novel therapeutic path for cortical-derived T-ALL. DisclosuresNo relevant conflicts of interest to declare.

Immunotherapy Targeting ST2/IL-33 Signaling in Myeloid Leukemia Stem Cells

▪Therapies for acute myeloid leukemia (AML) has barely changed over 30 years, while treatment for other blood cancers have made remarkable leaps forward. Recent advances in genomics have allowed molecular targeted therapies (i.e. FLT3-ITD, IDH, c-KIT inhibitors) extending survival, but most patients still succumb (Burd et al. Nat Med 2020). Therefore, developing more efficient, less toxic, and immune-based therapies for AML is an urgent unmet need. Previous studies showed that stromal cell-derived IL-33 stimulates myeloproliferative neoplasms (Mager et al. J Clin Invest 2015). Stimulation-2 (ST2), IL-33 receptor, contributes to leukemia stem cells (LSCs) survival in Cbfb-MYH11 mice (Wang et al . Sci Rep 2019). We showed that ST2 blockade enhanced graft versus leukemia activity against MLL-AF9 egfp AML after hematopoietic cell transplantation (Zhang et al . Sci Transl Med 2015). We and others, also, found that ST2 is expressed on normal murine and human hematopoietic stem cells (HSCs), respectively (Capitano et al. Blood Cells Mol Dis 2020; Alt et al. Biol Blood Marrow Transplant 2019). These data suggest a leukemia-promoting role of ST2/IL-33 signaling.To determine clinical relevance of ST2 in AML, we generated Kaplan-Meier curves using TCGA (n=173) and TARGET AML (n=187) databases. Decreased survival was observed in patients with high IL1RL1 (ST2 gene) which was validated in an independent database (AMLCG 1999 trial, n=417) (Fig. 1A). Since ST2 is expressed on HSCs, we interrogated if ST2 is expressed on LSCs defined as CD34 +CD38 - in the Princess Margaret Leukemia biobank (n=192), and found ST2 is higher on LSCs vs CD34 -CD38 +/- cells (Fig. 1B). We then sought to analyze ST2 on bone marrow samples comparing complete responders vs refractory patients to note that ST2 expression was increased in refractory patients' LSCs (Fig. 1C). To scrutinize the role of ST2 in initiating leukemogenesis, we performed limiting dilution transplantation using 500, 200, and 50 Lin -Sca-1 +c-KIT +-sorted LSCs from WT vs ST2 -/- MLL-AF9 egfp transduced cells. Frequency of LSCs in ST2 -/- cells was decreased by ~15-fold as opposed to WT cells [1:2141 (1:546-1:8405) vs 1:145 (1:75-1:283), p=3.37e-05] (Fig. 2A). We also tested leukemia maintenance, secondary transplantations from the primary recipients resulted in leukemia growth delay in ST2 -/- vs WT cells which was confirmed in tertiary transplantations (Fig. 2B-E). Self-renewal ability of LSCs is correlated to reactive oxygen species (ROS) (Testa et al. Exp Hematol 2016), and we found that ROS levels in ST2 -/- leukemic cells are markedly diminished in contrast to WT leukemic cells (Fig. 2F). ST2 deficiency in leukemic cells arrests G2/S/M cell cycle progression in LSCs (Fig. 2G-J). These data indicated that ST2 is indispensable for initiating and maintaining LSCs in MLL-AF9 AML.We next developed murine and human Fc-silenced-bispecific antibodies engaging mouse or human ST2 and CD3 (BsAb) built on the IgG[L]-scFv platform with proven ability to drive T cells into human tumors for effective tumor ablation (Santich et al. Sci Transl Med 2020; Park et al. J Immunother Cancer 2021) (Fig. 3A, 3E). Both BsAbs showed >90% purity by HPLC, stability under heat stress and low endotoxin. Animals did not exhibit any in vivo toxicity at BsAb doses of 0.4, 2, 5, 10 μg ip q 3 days x 6 doses (not shown). In the immunocompetent MLL-AF9 mice, murine anti-ST2 BsAb (BC281) treatment (10 μg i.p, 4 days post-AML challenge and given every three days for a total of 6 injections) resulted in extended survival compared to isotype control mice (Fig. 3B). Leukemic cells and LSCs were accordingly decreased in treated vs control group (Fig. 3C-D). We modeled humanized leukemic mice with MOLM-14 egfp cells and weekly injection of human CD8 + T cells in NOD.Cg-Prkdc scid Il2rg tm1Wjl/SzJ (NSG) mice (Fig. 3F). Animals treated with human anti-ST2 BsAb (BC282), using a similar regimen as for the immunocompetent model, led to better survival when compared to animals treated with mutated non-functional anti-ST2 BsAb (BC283) (Fig. 3G). Frequency of MOLM-14 egfp cells was lower in the BC282 vs BC283 group (Fig. 3H). These results suggested that anti-ST2 BsAbs can inhibit AML growth to improve survival.We concluded that ST2 is a potential therapeutic target, and ST2-specific T cell engaging BsAbs represent promising immunotherapeutics for AML. [Display omitted] DisclosuresCheung: Medical University of South Carolina: Patents & Royalties: inventor on the ST2 bispecific antibody patent application; Y-mabs Therapeutics and Abpro-Labs Inc: Patents & Royalties: inventor on multiple patents filed by MSK, including those licensed to Ymabs Therapeutics, Biotec Pharmacon, and Abpro-labs; Eureka Therapeutics: Membership on an entity's Board of Directors or advisory committees. Paczesny: Medical University of South Carolina: Patents & Royalties: inventor on the ST2 bispecific antibody patent application.

Subcutaneous Epcoritamab in Patients with Relapsed/Refractory Chronic Lymphocytic Leukemia: Preliminary Results from the Epcore CLL-1 Trial

Background: Small molecules such as Bruton tyrosine kinase (BTK) and B-cell lymphoma 2 (BCL2) inhibitors have transformed the management of chronic lymphocytic leukemia (CLL). However, such treatments are not curative, and patients (pts) with relapsed or refractory (R/R) CLL following multiple targeted treatments present an emergent challenge with very limited therapeutic options. In addition, success rates of autologous T-cell-based therapies in CLL have been disappointing. In vitro data in CLL cells suggest potentially high efficacy of bispecific T-cell engagers (Martens et al, J Immunother Cancer 2020), but clinical data are extremely limited.Epcoritamab (GEN3013; DuoBody ®-CD3×CD20) is a bispecific antibody that can induce potent activation and cytotoxic activity of CD4+ and CD8+ T cells to specifically eliminate CD20-expressing cells (van der Horst et al, Blood Cancer J 2021). In the first-in-human trial in R/R B-cell non-Hodgkin lymphoma (B-NHL; EPCORE NHL-1; NCT03625037), epcoritamab showed manageable safety and meaningful antitumor activity across a range of aggressive and indolent B-NHLs. The most common treatment-emergent adverse events (AEs) were pyrexia (69%), cytokine release syndrome (CRS; 59%), and injection-site reaction (47%); CRS events were all grade 1-2 and most occurred in cycle 1 (Clausen et al, J Clin Oncol 2021). However, as CLL is characterized by presence of (high numbers of) circulating tumor cells, acquired T-cell dysfunction, and variable expression of CD20, data obtained in B-NHL are difficult to extrapolate to CLL. Herein we present the first results from the dose-escalation part of a phase 1b/2 trial evaluating epcoritamab in pts with R/R CLL.Methods: In this open-label, multicenter, phase 1b/2 trial, toxicity and efficacy of epcoritamab are investigated in adults with R/R CLL (EPCORE CLL-1; NCT04623541). Eligible pts previously received ≥2 lines of systemic antineoplastic therapy, including treatment with (or intolerance to) a BTK inhibitor. Epcoritamab is subcutaneously administered via 1-mL injections in 4-week cycles as follows: once weekly in cycles 1-3, every 2 weeks in cycles 4-9, and monthly in cycles ≥10 until progression or unacceptable toxicity. Step-up dosing during cycle 1 (ie, priming dose followed by an intermediate dose, then full doses) is used in combination with steroid prophylaxis to reduce the risk of CRS. In the dose-escalation part, pts with R/R CLL received epcoritamab at 2 full-dose levels (24 and 48 mg) according to a modified 3+3 design. Primary end points of the dose-escalation part included dose-limiting toxicities (DLTs) during the first 28-day treatment cycle and the incidence and severity of AEs, CRS, immune effector cell-associated neurotoxicity syndrome (ICANS), and tumor lysis syndrome (TLS).Results: The first pt was enrolled on November 30, 2020. As of July 12, 2021, 7 pts with R/R CLL received epcoritamab subcutaneously administered at 2 full-dose levels: 24 mg (n=3) and 48 mg (n=4). Six pts completed the DLT evaluation period, and 5 pts had a full response assessment. Pts had received a median of 4 lines of prior therapy (range, 2-5). Six of 7 pts had poor-risk features of del(17p), TP53 mutations, or both. Three of 7 pts had bulky disease.No DLTs occurred at 24 or 48 mg. The most common treatment-emergent AEs (>30%) were CRS (100%), fatigue (71%), injection-site reaction (43%), and nausea (43%). All pts experienced CRS in the first cycle, but no CRS events were higher than grade 2. No cases of ICANS were observed. TLS was not observed. Antileukemic activity has been observed at both dose levels, with partial responses in 3 of 5 pts. Updated clinical and pharmacokinetic data, including data for additional pts treated with epcoritamab, will be presented.Conclusions: These data suggest that epcoritamab is well tolerated in pts with R/R CLL at dose levels up to 48 mg and has clinical activity in pts with high-risk features. The expansion part of this study in pts with R/R CLL and Richter syndrome will open later this year. DisclosuresKater: Janssen, AstraZeneca: Other: Ad Board, steering committee, Research Funding; BMS, Roche/Genentech: Other: Ad Board, , Research Funding; Genmab, LAVA: Other: Ad Board, Steering Committee; Abbvie: Honoraria, Other: Ad Board, Research Funding. Niemann: CSL Behring, Genmab, Takeda, Octapharma: Consultancy; Abbvie, AstraZeneca, Janssen: Consultancy, Research Funding; Novo Nordisk Foundation: Research Funding. Hutchings: Roche: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; Novartis: Research Funding; Incyte: Research Funding; Janssen: Honoraria, Research Funding; Genmab: Consultancy, Honoraria, Research Funding; Celgene: Research Funding; Genentech: Honoraria, Research Funding. Chen: Genmab: Current Employment. Rios: Genmab: Current Employment. Palenski: AbbVie: Current Employment. Li: Genmab: Current Employment. Mato: AbbVie: Consultancy, Research Funding; Adaptive Biotechnologies: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; MSKCC: Current Employment; Genmab: Research Funding; Johnson and Johnson: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; LOXO: Consultancy, Research Funding; Nurix: Research Funding; DTRM BioPharma: Consultancy, Research Funding; TG Therapeutics: Consultancy, Other: DSMB, Research Funding; BeiGene: Consultancy, Research Funding; Acerta/AstraZeneca: Consultancy, Research Funding; AstraZeneca: Consultancy; Sunesis: Consultancy, Research Funding.

A Phase 1 Study of XmAb18968, a CD3-CD38 Bispecific Antibody for the Treatment of Patients with Relapsed/Refractory Acute Leukemia and T Cell Lymphoblastic Lymphoma

Background:Outcomes of adults with relapsed/refractory T-cell acute lymphoblastic leukemia or lymphoma (T-ALL or T-LBL respectively) and acute myeloid leukemia (AML) have remained poor despite the availability of newer agents. CD38 is a 45 kDa transmembrane glycoprotein expressed by lymphoid and myeloid cells with several important functions including a role in immune escape from tumor cells [Chillemi A et al. Front Immunol 2017, Furano A et al. J Immunol 1990]. Several studies have demonstrated that CD38 is expressed in tumor cells of patients with T-ALL and AML and potentially targetable using CD38 blocking agents [Naik J et al. Haematologica 2019, Bride KL et al. Blood 2018, Tembhare et al. J Immunother Cancer 2020, Farber M et al. ASH 2018]. XmAb18968 is structurally distinct CD3-CD38 bi-specific T-cell engager with a full fragment crystallizable (Fc) domain modified to minimize Fcγ receptor binding and non-selective activation of T cells and other immune effector cells. XmAb18968 has optimized relative affinities for both CD3 and CD38 which results in reduced cytokine release without compromising target cell killing. We hypothesize targeting CD38 in relapsed/refractory- T-cell ALL/LBL and AML is safe and feasible using XmAb18968, a novel CD3-CD38 bispecific antibody.Study design and methods:This is an investigator-sponsored multi-institutional phase I study evaluating the safety and tolerability of XmAb18968. Patients aged 18 years or above with T-ALL, T-LBL or AML (including undifferentiated leukemia and bi phenotypic leukemia), in relapsed/refractory status (at least one line of prior therapy) including measurable residual disease relapse, CD38 expression ≥ 20%, and adequate organ function will be eligible. Major exclusion criteria are hematopoietic cell transplantation (HCT) within 6 months of enrollment, active acute GVHD, veno-occlusive disease, and acute promyelocytic leukemia. The study is planned to be conducted at 6 sites in United States.The primary endpoint is to determine the recommended phase 2 dose (RP2D) and toxicity profile of XmAb18968. The secondary endpoints include determination of response rates, duration of response, survival and pharmacokinetics. Exploratory endpoints include correlation of responses with genomic profile, assessment of serum cytokine response, identifying the changes in phenotypic expression of activated T-cells and leukemic cells, correlation of the phenotypic expression with changes in the transcriptome at the single-cell level, proteomics evaluation of cytokine secretion at the single-cell level and correlation of response with N-glycan profiling, quantitative site-occupancy and direct glycopeptide analysis.The study will follow 3+3 design for dose escalation and de-escalation in case of dose limiting toxicity (DLT). Dose escalation will proceed in two separate groups: Group A for subjects with T-ALL and T-LBL and Group B for subjects with AML. Patients will be entered sequentially to each dose level, starting with the first dose level. The DLT observation period for dose-escalation will be 28-days. RP2D will be defined as the highest dose level at which none of the first 3 treated subjects, or no more than 1 of the first 6 treated subjects experience a DLT. A minimum of 24 and a maximum of 60 patients will be needed for the dose escalation phase. DisclosuresGuru Murthy: Curio Sciences: Honoraria; Techspert: Consultancy; Qessential: Honoraria; CancerExpertNow: Honoraria; DAVA Oncology: Honoraria; TG Therapeutics: Other: Advisory board meeting; Cardinal health: Honoraria; Guidepoint: Consultancy. Johnson: Miltenyi Biotec: Research Funding. Abedin: AltruBio: Research Funding; Amgen: Honoraria; Agios: Honoraria; Helsinn: Research Funding; Pfizer: Research Funding; Astellas Pharma Inc.: Research Funding; Actinium: Research Funding. Stock: Pfizer: Consultancy, Honoraria, Research Funding; amgen: Honoraria; agios: Honoraria; jazz: Honoraria; kura: Honoraria; kite: Honoraria; morphosys: Honoraria; servier: Honoraria; syndax: Consultancy, Honoraria; Pluristeem: Consultancy, Honoraria. Shah: Precision Biosciences: Consultancy; Kite, a Gilead Company: Consultancy, Honoraria, Other: Expenses, Research Funding; Pharmacyclics/Janssen: Honoraria, Other: Expenses; Acrotech/Spectrum: Honoraria; BeiGene: Consultancy, Honoraria; Amgen: Consultancy; Pfizer: Consultancy, Other: Expenses; Novartis: Consultancy, Other: Expenses; Bristol-Myers Squibb/Celgene: Consultancy, Other: Expenses; Adaptive Biotechnologies: Consultancy; Servier Genetics: Other; Jazz Pharmaceuticals: Research Funding; Incyte: Research Funding. Leonard: Amgen: Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees. Pratz: Agios: Consultancy; BMS: Consultancy, Honoraria; Novartis: Consultancy; Astellas: Consultancy, Honoraria, Research Funding; Cellgene: Consultancy, Honoraria; Millenium: Research Funding; University of Pennsylvania: Current Employment; Abbvie: Consultancy, Honoraria, Research Funding. Luger: Syros: Honoraria; Agios: Honoraria; Daiichi Sankyo: Honoraria; Jazz Pharmaceuticals: Honoraria; Brystol Myers Squibb: Honoraria; Acceleron: Honoraria; Astellas: Honoraria; Pfizer: Honoraria; Onconova: Research Funding; Celgene: Research Funding; Biosight: Research Funding; Hoffman LaRoche: Research Funding; Kura: Research Funding. Badar: Pfizer Hematology-Oncology: Membership on an entity's Board of Directors or advisory committees. Atallah: Novartis: Consultancy, Honoraria, Research Funding; Amgen: Consultancy; Abbvie: Consultancy, Speakers Bureau; Takeda: Consultancy, Research Funding; BMS: Honoraria, Speakers Bureau; Pfizer: Consultancy, Research Funding.

65 Identification of frequently presented non-mutated tumor-specific immunogens for the development of both off-the-shelf and personalized vaccines without need for tumor biopsy

BackgroundVaccines have little chance of destroying heterogeneous tumor cells since they rarely induce polyclonal T-cell responses against the tumor. The main challenge is the accurate identification of tumor targets recognizable by T cells. Presently, 6–8% of neoepitopes selected based on the patients‘ tumor biopsies are confirmed as real T cell targets.1 2. To overcome this limitation, we developed a computational platform called Personal Antigen Selection Calculator (PASCal) that identifies frequently presented immunogenic peptide sequences built on HLA-genetics and tumor profile of thousands of real individuals.3 Here we show the performance of PASCal for the identification of both shared and personalized tumor targets in metastatic colorectal cancer (mCRC) and breast cancer subjects.MethodsExpression frequency of the tumor-specific antigens (TSAs) ranked in PASCal’s database (based on 7,548 CRC specimen) was compared to the RNA-sequencing data of CRC tumors obtained from TCGA. Using PASCal, 12 shared PEPIs (epitopes restricted to at least 3 HLA class I alleles of a subject from an in silico cohort) derived from 7 TSAs were selected as frequent targets (calculated probability: average 2.5 [95%CI 2.4–2.8] TSAs/patient). Spontaneous immune responses against each of the twelve 9mer peptides were determined by ELISpot using PBMCs of 10 mCRC subjects who participated in the OBERTO-101 study.4 PEPIs selected for a breast cancer subject based on her HLA genotype were also tested.ResultsEach of the 106 tumors analyzed expressed at least 13, average 15 of the 20 top-ranked TSAs in PASCal’s database confirming their prevalence in CRC. 7/10 subjects had spontaneous CD8+ T-cell responses against at least one peptide selected with PASCal. Each peptide (12/12) was recognized by at least one patient. Patients‘ T-cells reacted with average 3.6/12 (30%) peptides confirming the expression of average 2.8 [95%CI 1.0–4.6] TSAs (n=10). After HLA-matching, among the subjects for whom we could select at least 4 PEPIs (average 5) from the list of 12 peptides (n=6), average 2.5 (50%) peptides were positive. Of the 12 PEPIs selected with PASCal for a breast cancer subject, we detected spontaneous T-cell responses against 9 PEPIs, indicating that at least 75% of the selected peptides were present in the subject’s tumor and were recognized by T-cells.ConclusionsPASCal platform accommodates both tumor- and patient heterogeneity and identifies non-mutated tumor targets that may trigger polyclonal cytotoxic T-cell responses. It is a rapid tool for the design of both off-the-shelf and personalized cancer vaccines negating the need for tumor biopsy.ReferencesWells DK, van Buuren MM, Dang KK, et al. Key parameters of tumor epitope immunogenicity revealed through a consortium approach improve neoantigen prediction. Cell 2020:183(3):818–34.e13.Bulik-Sullivan B, Busby J, Palmer CD, et al. Deep learning using tumor HLA peptide mass spectrometry datasets improves neoantigen identification. Nat Biotech 2018:37:55–63.Somogyi E, Csiszovszki Z, Lorincz O, et al. 1181PDPersonal antigen selection calculator (PASCal) for the design of personal cancer vaccines. Annal Oncol 2019:30(Supplement_5):v480-v81.Hubbard J, Cremolini C, Graham R, et al. P329 PolyPEPI1018 off-the shelf vaccine as add-on to maintenance therapy achieved durable treatment responses in patients with microsatellite-stable metastatic colorectal cancer patients (MSS mCRC). J ImmunoTher Cancer 2019:7(1):282.

283 TIM-3 blockade modulates the tumor microenvironment improving the outcome of preclinical pediatric diffuse midline glioma models

BackgroundDiffuse Midline Gliomas (DMGs), encompassing Diffuse Intrinsic Pontine Gliomas (DIPGs), are the most aggressive pediatric brain tumors. Their meager survival has not changed despite the combination of radiotherapy with targeted therapies emphasizing the urgent need for effective treatments. Recent research suggested that the DIPG tumor microenvironment is neither highly immunosuppressive nor inflammatory.1 These analyses showed the lack of infiltrating lymphocytes and the abundance of CD11b+ cells. TIM-3 is a member of the T-cell immunoglobulin and mucin domain protein family expressed on multiple immune cell types, including T cells, Treg, NK cells, monocytes, dendritic cells, and microglia, where it potently regulates not only adaptive immunity but also innate immunity.2–3 Therefore, TIM-3 inhibitors could challenge several components in the tumor microenvironment, thereby providing potentially effective treatment for DMGs.MethodsNP53 and XFM murine DIPG cell lines were used for animal experiments in immunocompetent orthotopic models. The tumors were processed by mechanical and enzymatic digestion and immune populations were analyzed by a flow cytometry panel. Antibodies against NK cells (NK1.1), CD4 (GK1.5), CD8 (CD8β) were used for animal depletion experiments alone or in combination.ResultsIn silico assessment of TIM-3 expression in DIPG datasets showed a robust expression of this gene. Moreover, single-cell sequencing analyses of DIPG biopsies uncover its expression in the myeloid compartment (especially in microglia). In vivo efficacy studies showed that treatment with anti-TIM-3 antibody significantly increased the overall survival in two DIPG immunocompetent orthotopic animal models (doubling the median), lead to long-term survivors free of disease (50%) and showed immune memory. Analyses of CD45+ populations in the tumor microenvironment showed a significant increase in microglia, granulocytes, NK and CD8+ cells corresponding with a NK and T-cell activate phenotypes in treated-mice. In addition, we have a substantial decrease in the Treg population, which causes an increase in the CD8/Treg ratio. CD4 and CD8 T-cell depletion led to a significant but not total loss of treatment efficacy. NK cells depletion also reduced the effectiveness of this therapy, albeit to a lesser extent than CD4-CD8 depletion. We are currently investigating the role of microglia in the outcome of the treatment.ConclusionsOur data uncovered TIM-3 as a potential target for the treatment of DIPG tumors. Inhibition of this molecule led to a potent antitumor effect mediated by a profound tumor microenvironment remodelling.ReferencesLieberman NAP, DeGolier K, Kovar HM, et al. Characterization of the immune microenvironment of diffuse intrinsic pontine glioma: implications for development of immunotherapy. Neuro Oncol 2019;21(1):83–94. doi:10.1093/neuonc/noy145.Acharya N, Sabatos-Peyton C, Anderson AC. Tim-3 finds its place in the cancer immunotherapy landscape. J Immunother Cancer 2020;8(1):e000911. doi:10.1136/jitc-2020-000911.Wolf Y, Anderson AC, Kuchroo VK. TIM3 comes of age as an inhibitory receptor. Nat Rev Immunol 2020;20(3):173–185. doi:10.1038/s41577-019-0224-6

59 Associations between KIR/KIR-ligand genotypes and clinical outcome for patients with advanced solid tumors receiving BEMPEG plus nivolumab combination therapy in the PIVOT-02 trial

BackgroundHigh-dose IL2 therapy has shown clinical benefit in metastatic melanoma and renal cell carcinoma, however only in a select subset of patients. Bempegaldesleukin (BEMPEG), a novel CD122-preferential IL2 pathway agonist, preferentially binds the heterodimeric IL2βγR predominantly expressed on NK and CD8 T cells and minimizes binding to the IL2αR expressed on immunosuppressive Tregs. BEMPEG monotherapy in Phase I clinical trials induced proliferation and activation of NK cells in the blood and tumor microenvironment.1 NK activation is dependent on the balance of inhibitory and excitatory signals transmitted by NK receptors, including Fc-gamma receptors (FCγRs) and killer immunoglobulin-like receptors (KIRs) along with their KIR-ligands. The repertoire of KIRs/KIR-ligands an individual inherits and the single-nucleotide polymorphisms (SNPs) of FCγRs can influence NK cell function and affect responses to immunotherapies.2–4 Thus, we sought to investigate whether distinct immunogenotypes are associated with clinical response of patients enrolled in PIVOT-02, a Phase II study of BEMPEG plus nivolumab.Methods200 patients with advanced solid tumors enrolled in PIVOT-02 who were not previously treated with immunotherapy (immunotherapy-naïve, ‘IO’) had DNA available for genotyping and clinical data for correlative analyses. All patients received 0.006mg/kg BEMPEG plus 360mg nivolumab every 3 weeks.5 KIR/KIR-ligand gene status was assessed by real-time SYBR green PCR melt-curve analyses and PCR-SSP. FCγR SNP status was determined using Taqman primers/probes for FCγR2A, and FCγR3A and FCγR2C were determined using RNaseH primers/probes.6 Clinical outcome parameters included objective response rate (ORR), progression-free survival (PFS), and tumor shrinkage (TS, defined as best objective response <0% by RECIST). Preliminary statistical analyses were done using a chi-square test, log-rank test, and Wilcoxon rank-sum test, respectively.ResultsKIR2DL2+/C1+ IO patients observed significantly greater TS (p=0.015) and a trend towards improved ORR (p=0.060) and increased PFS (p=0.058) compared to IO patients who were not KIR2DL2+/C1+. IO patients who were KIR2DL2+/C1+/KIR3DL1+/Bw4+ showed significantly improved ORR (p=0.014) and greater TS (p=0.044) compared to IO patients who were not KIR2DL2+/C1+/KIR3DL1+/Bw4+, with no significance found for PFS in these patients. FCγR polymorphisms did not influence ORR/PFS/TS.ConclusionsNK cells may play an important role in the anti-tumor efficacy of BEMPEG plus nivolumab, and NK activation is influenced by certain immunogenotypes. Similar to previous findings,2–4 the status of KIR2DL2+/C1+ and KIR2DL2+/C1+/KIR3DL1+/Bw4+ was associated with the response to BEMPEG plus nivolumab treatment in the PIVOT-02 trial. The potential to utilize these genotypes in clinical decision-making for immunotherapy treatment requires further investigation.Trial RegistrationClinicalTrialsgov NCT02983045ReferencesBentebibel S-E, et al. A first-in-human study and biomarker analysis of NKTR-214, a Novel IL2βγ-Biased cytokine, in patients with advanced or metastatic solid tumors. Cancer Discov 2019;9:711–21.Erbe AK, et al. Follicular lymphoma patients with KIR2DL2 and KIR3DL1 and their ligands (HLA-C1 and HLA-Bw4) show improved outcome when receiving rituximab. J Immunother Cancer 2019;7(1):70.Erbe AK, et al. Neuroblastoma patients’ KIR and KIR-Ligand genotypes influence clinical outcome for dinutuximab-based immunotherapy: A report from the Children’s Oncology Group. Clin Cancer Res 2018;24(1):189–96.Erbe AK, et al. FCGR polymorphisms influence response to IL2 in metastatic renal cell carcinoma. Clin Cancer Res 2017;23(9):2159–68.Diab A, et al. Bempegaldesleukin (NKTR-214) plus nivolumab in patients with advanced solid tumors: Phase I dose-escalation study of safety, efficacy, and immune activation (PIVOT-02). Cancer Discov 2020;10:1–16.Erbe AK, et al. Genotyping single nucleotide polymorphisms and copy number variability of the FCGRs expressed on NK cells. Methods Mol Biol 2016;1441:43–56.Ethics ApprovalThe study was conducted in accordance with Good Clinical Practice guidelines and the Declaration of Helsinki. The Protocol (online only) was approved by independent ethics committees and the relevant institutional review board at each site. All patients provided written informed consent.

909P A phase II study of the anti-programmed cell death-1 (PD-1) antibody penpulimab in patients with metastatic nasopharyngeal carcinoma (NPC) who had progressed after two or more lines of chemotherapy: Updated results

Nasopharyngeal carcinoma (NPC) is a rare, but geographically distributed tumor with a high incidence in South China and Southeast Asia. Penpulimab had demonstrated encouraging anti-tumor activity and favorable safety profile in NPC patients with disease progression after ≥ 2 prior lines of therapy in the previous report (Chen et al, J Immunother Cancer 2020). We updated the latest long term efficacy and safety data.

Highlights from Recent Cancer Literature

Highlights from Recent Cancer Literature

Abstract 1858: SBT6290, a systemically administered Nectin4-directed TLR8 ImmunoTAC™ product candidate, is designed for tumor-localized activation of myeloid cells

Abstract SBT6290 is a novel product candidate comprised of a selective TLR8 agonist conjugated to a Nectin4-specific monoclonal antibody, designed for systemic delivery and tumor-localized activation of myeloid cells. Nectin4 is a cell surface adhesion molecule that is overexpressed in multiple solid tumor types including bladder, triple negative breast, squamous head and neck, and non-small cell lung cancers, with limited expression in normal tissues. Nectin4-expressing solid tumors display substantial myeloid cell infiltrate. Activation of these myeloid cells in the tumor microenvironment has emerged as a promising approach in overcoming resistance mechanisms to current cancer immunotherapies. TLR8 is highly expressed in myeloid cell types prevalent in human tumors, including conventional dendritic cells (DCs) and macrophages. TLR8 agonism in human myeloid cells activates a broad spectrum of anti-tumor immune mechanisms, including proinflammatory cytokine production, repolarization of suppressive myeloid cells, and the priming of CTL responses. Here, we show that SBT6290 activates human myeloid cells by SBT6290 in a Nectin4-dependent manner and that a SBT6290 mouse surrogate confers single agent anti-tumor activity in preclinical studies. In vitro studies with human immune cells demonstrate that SBT6290 induces multiple anti-tumor immune mechanisms including proinflammatory cytokine and chemokine production, inflammasome activation, direct activation of DCs and indirect activation of T and NK cell cytolytic activity. This activity is Nectin4-specific and requires SBT6290 engagement of Fcγ receptors on the surface of myeloid cells to facilitate uptake of the conjugate into myeloid cells. Notably, SBT6290 is >100-fold more active than free, unconjugated TLR8 agonist and demonstrates activity on tumor cells with Nectin4 overexpression that correlates with levels found in primary tumor samples. Nectin4 was recently described to be a ligand for T cell immunoreceptor with Ig and ITIM domains (TIGIT), an inhibitory receptor considered to be a promising new target for cancer immunotherapy (J Immunother Cancer. 2020; 8(1): e000266). The SBT6290 binding domain blocks the interaction between TIGIT and Nectin4, potentially contributing to the T and NK cell activation induced by SBT6290. Systemic administration of a SBT6290 surrogate in mice bearing Nectin4-expressing tumors results in intra-tumoral myeloid and T cell activation and increased overall survival. The preclinical data described here demonstrate the potential for SBT6290 to drive anti-tumor responses and support continued preclinical development of SBT6290 for Nectin4-expressing tumors. Citation Format: Michael R. Comeau, Heather Metz, Brenda Stevens, Damion Winship, Jamie Brevik, Marcus Rhodehamel, Monica Childs, Elsa Hay, Jenny Chang, Li-Qun Fan, Hengyu Xu, Jonathan Grey, Jeffrey Adamo, Ben Setter, Ray Carillo, Sean W. Smith, Phil Tan, Robert Dubose, Yvette Latchman, Peter Baum, Valerie Odegard. SBT6290, a systemically administered Nectin4-directed TLR8 ImmunoTAC™ product candidate, is designed for tumor-localized activation of myeloid cells [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 1858.

Effects of baseline lactate dehydrogenase (LDH), interferon gamma (IFN-g) expression, and tumor mutational burden (TMB) on treatment response to first-line atezolizumab (A) + vemurafenib (V) and cobimetinib (C) in BRAFV600 mutation–positive advanced melanoma.

9523 Background: The phase 3 IMspire150 study showed that first-line A+V+C improved investigator-assessed PFS vs placebo (P)+V+C in BRAFV600E/K mutation–positive advanced melanoma (hazard ratio 0.78; P=.0249). Prior biomarker analyses showed that IFN-g or TMB > 10 mut/Mb were associated with greater PFS benefits with A+V+C (Lewis et al. J ImmunoTher Cancer 2020;8:A188-A189). We further evaluated the association of these biomarkers with outcomes. Methods: Exploratory recursive partitioning analysis (RPA) was used to model associations between PFS and age ( < 65 vs ≥65 y), Eastern Cooperative Oncology Group performance status (0 vs 1), liver metastases (yes vs no), metastatic sites (≤3 vs > 3), sum of longest tumor diameters ( < 44 mm vs ≥44 mm), baseline LDH (normal [n] vs elevated [e]), TMB ( < 10 vs ≥10 mut/Mb), PD-L1 (negative vs positive), and IFN-g (high [h; > Quartile 3; Q3] vs intermediate [ > Q1 and ≤Q3] vs low [≤Q1]). Time-to-event analyses were summarized using Kaplan-Meier estimates. Results: The RPA analysis included 208/256 (81.3%) patients (pts) from the A+V+C arm of IMspire150 for whom LDH, TMB, IFN-g, and PD-L1 data were available. RPA showed that LDH was associated with PFS. In pts treated with A+V+C and n-LDH, h-IFN-g signature was associated with longer PFS and higher rates of objective response (OR) and complete response (CR) vs low/intermediate (l/i) IFN-g (2-y PFS: 59% vs 38%; ORR: 77% vs 69%; CR: 38% vs 15%, respectively); TMB ≥10 mut/Mb was associated with more favorable outcomes in pts with e-LDH (Table). In contrast, neither IFN-g nor TMB discriminated PFS outcomes in n-LDH or e-LDH pt subgroups receiving P+V+C. Pts with e-LDH and TMB < 10 mut/Mb had poor PFS outcomes, with 2-y PFS rates of 9% and 3% and lower rates of OR (51% and 62%) and CR (5% and 9%) in the A+V+C and P+V+C arms, respectively. Similar trends were observed for duration of response (DOR), and for the subset of pts with BRAFV600E mutation–positive melanoma. A+V+C improved PFS vs P+V+C across all subgroups with the exception of e-LDH and TMB < 10. Conclusions: IFN-g and TMB discriminated PFS benefit in pts receiving A+V+C but not for those receiving P+V+C. Durable responses were observed for pts treated with A+V+C in the n-LDH + h-IFNg subgroups.[Table: see text]