Safety and Activity of Varlilumab, a Novel and First-in-Class Agonist Anti-CD27 Antibody, in Patients With Advanced Solid Tumors

2017 ◽  
Vol 35 (18) ◽  
pp. 2028-2036 ◽  
Author(s):  
Howard A. Burris ◽  
Jeffrey R. Infante ◽  
Stephen M. Ansell ◽  
John J. Nemunaitis ◽  
Geoffrey R. Weiss ◽  
...  
Keyword(s):  
T Cell ◽  
Antitumor Activity ◽  
Solid Tumors ◽  
T Cell Activation ◽  
Dose Escalation ◽  
Costimulatory Molecule ◽  
Progression Free Survival ◽  
Advanced Solid Tumors ◽  
Free Survival ◽  
Metastatic Rcc

Purpose CD27, a costimulatory molecule on T cells, induces intracellular signals that mediate cellular activation, proliferation, effector function, and cell survival upon binding to its ligand, CD70. Varlilumab is a novel, first-in-class, agonist CD27 antibody that stimulates the CD27 pathway, which results in T-cell activation and antitumor activity in tumor models. This first-in-human, dose-escalation and expansion study evaluated the safety, pharmacology, and activity of varlilumab in patients with advanced solid tumors. Methods In a 3 + 3 dose-escalation design (n = 25), patients received a single dose of varlilumab (0.1, 0.3, 1.0, 3.0, or 10 mg/kg intravenously) with a 28-day observation, followed by up to five multidose cycles (one dose per week for 4 weeks), depending on tumor response. Expansion cohorts were initiated at 3.0 mg/kg in patients with melanoma (n = 16) and renal cell carcinoma (RCC; n = 15). Primary objectives were to assess the safety and the maximum tolerated and optimal biologic doses of varlilumab. Secondary objectives were to evaluate the pharmacokinetics, pharmacodynamics, and clinical antitumor activity of varlilumab. Results Exposure to varlilumab was linear and dose proportional across dose groups. Only one patient experienced a dose-limiting toxicity—grade 3 transient asymptomatic hyponatremia at the 1.0-mg/kg dose level. Treatment-related adverse events were generally grade 1 or 2 in severity. Evidence of biologic activity consistent with CD27 stimulation—chemokine induction, T-cell stimulation, regulatory T cell depletion—was observed at all dose levels. A patient with metastatic RCC experienced a partial response (78% shrinkage, progression-free survival > 2.3 years). Eight patients experienced stable disease > 3 months, including a patient with metastatic RCC with progression-free survival of > 3.9 years. Conclusion Dose escalation of varlilumab to 10 mg/kg was well tolerated without identification of a maximum tolerated dose. Varlilumab was biologically and clinically active.

Phase I dose escalation study of recombinant interleukin-21 (rIL-21; BMS-982470) in combination with nivolumab (anti-PD-1; BMS-936558; ONO-4538) in patients (pts) with advanced or metastatic solid tumors.

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. TPS3112-TPS3112 ◽  
Author(s):  
Laura Quan Man Chow ◽  
Michael S. Gordon ◽  
Theodore F. Logan ◽  
Scott J. Antonia ◽  
Shailender Bhatia ◽  
...  
Keyword(s):  
T Cell ◽  
Antitumor Activity ◽  
Phase I ◽  
Solid Tumors ◽  
Clinical Outcomes ◽  
Dose Escalation ◽  
Fixed Dose ◽  
Weekly Schedule ◽  
Advanced Solid Tumors ◽  
Biologic Activity

TPS3112 Background: Programmed death-1 (PD-1) is an immune checkpoint receptor that attenuates T-cell activation by binding to its ligands, PD-L1 and PD-L2. Nivolumab, a PD-1 receptor blocking antibody, has shown durable antitumor activity in pts with various solid tumors in two phase I clinical trials. The cytokine rIL-21 has also shown antitumor activity in selected solid tumors. We hypothesized that combining rIL-21-induced stimulation of T-cell and NK-cell function in conjunction with T-cell checkpoint blockade using nivolumab could enhance biologic activity resulting in improved clinical outcomes, as compared with either agent alone. We describe a novel phase I study investigating the biologic activity and clinical outcomes of the combination in pts with advanced solid tumors. Methods: This ongoing study (N=160) includes a dose escalation phase (Part 1) using a 3 + 3 design followed by an expansion phase (Part 2). In Part 1 (N=60), successive pt cohorts with advanced solid tumors are being treated with escalating doses of rIL-21 (10, 30, 50, 75, or 100 µg/kg IV) on two distinct schedules (Arms A and B) in combination with fixed-dose nivolumab (3 mg/kg q 2 weeks) in 6 week cycles. Arm A administers rIL-21 on a weekly schedule, given on day 1 in weeks 1–4 of the 6 week cycle. Arm B administers rIL-21 at 3x per week during weeks 1 and 3 of the 6 week cycle. In Part 2, pts with renal cell carcinoma (N=50) or non-small cell lung carcinoma (N=50) will each be randomized to treatment at the maximum tolerated dose (MTD) or maximum administered dose, if no MTD is determined, for Arm A or Arm B. Therapy for pts who are stable or responding in Parts 1 and 2 may be continued for up to 2 years or until treatment discontinuation criteria are met. Primary objectives are to evaluate the safety of rIL-21 + nivolumab, and to define the MTD of the 2 schedules. Secondary and exploratory objectives include a preliminary assessment of the antitumor activity, pharmacokinetics, immunoregulatory activity (peripheral blood, tumor) and immunogenicity of this combination. Clinical trial information: NCT01629758.

A phase I study of CD40 agonist ABBV-927 plus OX40 agonist ABBV-368 with or without the PD-1 inhibitor budigalimab in patients with advanced solid tumors.

2020 ◽  
Vol 38 (15_suppl) ◽  
pp. TPS3147-TPS3147
Author(s):  
John D. Powderly ◽  
Anthony Tolcher ◽  
Patricia LoRusso ◽  
Martha Elizabeth Blaney ◽  
Daniel Dacosta ◽  
...  
Keyword(s):  
T Cell ◽  
Solid Tumors ◽  
T Cell Activation ◽  
Cell Activation ◽  
Group Performance ◽  
Costimulatory Molecule ◽  
Eastern Cooperative Oncology Group ◽  
Cell Activity ◽  
Advanced Solid Tumors ◽  
Disease Specific

TPS3147 Background: CD40 is a key costimulatory molecule for both the innate and adaptive immune systems that is essential for T-cell activation and proliferation. OX40 is a costimulatory molecule that is involved in enhancing nascent immune responses and concomitantly acts to suppress regulatory T-cell activity. ABBV-927 and ABBV-368 are potent agonistic antibodies against CD40 and OX40, respectively. This open-label, Phase 1 study will evaluate the doublet combination of ABBV-927 and ABBV-368 and the triplet combination of ABBV-927, ABBV-368, and the programmed cell death protein-1 (PD-1) inhibitor budigalimab in patients with advanced solid tumors. Methods: For this study (NCT03893955), patients must be ≥18 y with an Eastern Cooperative Oncology Group performance status of 0-1. Patients must have an advanced solid tumor that has progressed on standard therapies. Disease-specific cohorts will include patients with non-small cell lung cancer (NSCLC) and triple-negative breast cancer (TNBC). Patients with NSCLC must have previously received a PD-1/PD-ligand 1 inhibitor and a platinum-based therapy and no more than one prior immunotherapy. Patients with TNBC must not have received immunotherapy. Patients with uncontrolled central nervous system metastases will be excluded. The recommended Phase 2 dose (RP2D) will first be identified with ABBV-927 + ABBV-368 in patients with solid tumors (Arm A) and will be expanded in disease-specific cohorts including TNBC. The RP2D of ABBV-927 + ABBV-368 + budigalimab will be identified in patients with NSCLC (Arm B). The primary endpoints are determination of the RP2D of ABBV-927 + ABBV-368, the RP2D of ABBV-927 + ABBV-368 + budigalimab, and overall response rate; duration of response, progression-free survival, safety, and pharmacokinetics are secondary endpoints. Screening began on 21 May 2019, and enrollment is ongoing. Clinical trial information: NCT03893955 .

FPT155-001: A phase Ia/Ib study of FPT155 (CD80-FC) in patients with advanced solid tumors.

2019 ◽  
Vol 37 (8_suppl) ◽  
pp. TPS42-TPS42
Author(s):  
Michael Millward ◽  
Hui Kong Gan ◽  
Anthony M. Joshua ◽  
James Chun-Yen Kuo ◽  
Amy Prawira ◽  
...  
Keyword(s):  
T Cell ◽  
Solid Tumors ◽  
T Cell Activation ◽  
Dose Escalation ◽  
Cell Activation ◽  
Objective Response ◽  
Advanced Solid Tumors ◽  
Multiple Tumor ◽  
Secondary Endpoints ◽  
Phase 1B

TPS42 Background: Despite recent advances in immunotherapy, many patients with advanced solid tumors are refractory to available therapies or eventually relapse. Novel immune therapies are needed with differentiated mechanisms of action that result in improved response rates and durability across a broad range of tumors. FPT155 is a first-in-class therapeutic being developed to meet this need. FPT155 is a recombinant fusion protein composed of the extracellular domain of human CD80 fused with the Fc domain of human immunoglobulin G1. It is designed to act as a potent stimulator of anti-tumor immunity through CD28 and thereby co-stimulate T cell responses only in the presence of antigenic T cell receptor (TCR) signaling. FPT155 alone does not induce spontaneous cytokine release by primary human immune cells, in contrast to a CD28 superagonist antibody that exerts TCR stimulus-independent activity. FPT155 also blocks CTLA-4 from competing for endogenous CD80, allowing CD28 signaling to prevail in T cell activation. A murine surrogate of FPT155 is a potent inhibitor of tumor growth that induces complete tumor regression in multiple tumor models, including models that are insensitive to anti-PD1 or anti-CTLA4. Methods: The FPT155-001 study is a Phase 1a/1b open-label, multicenter, dose escalation and expansion study to evaluate the safety and tolerability of FPT155 monotherapy. Phase 1a dose escalation includes an accelerated titration design followed by a standard 3+3 design until the recommended dose for Phase 1b is determined by evaluation of all available safety, pharmacokinetic (PK), and pharmacodynamic (PD) data. Eligible patients with advanced solid tumors who are refractory to all standard therapy for their malignancy will be enrolled in Phase 1a. Phase 1b dose expansion will enroll patients with select tumor types. The primary endpoint is safety in both phases. Key secondary endpoints in Phase 1a include characterization of the FPT155 PK profile and immunogenicity. Key secondary endpoints in Phase 1b include objective response rate, duration of response, progression free survival, and disease control rate. The FPT155-001 trial opened for enrollment in October 2018 and is in progress. Clinical trial information: Submitted - awaiting registration number.

AGEN1181, a clinical stage Fc-engineered anti-CTLA-4 antibody with improved therapeutic potential for the treatment of patients with advanced malignancies.

2020 ◽  
Vol 38 (15_suppl) ◽  
pp. TPS3157-TPS3157
Author(s):  
Steven O'Day ◽  
Chethan Ramamurthy ◽  
Andrea J. Bullock ◽  
Anthony B. El-Khoueiry ◽  
Lernik Ohanjanian ◽  
...  
Keyword(s):  
T Cell ◽  
Solid Tumors ◽  
T Cell Activation ◽  
Dose Escalation ◽  
First Generation ◽  
Therapeutic Potential ◽  
Phase 1 ◽  
Advanced Solid Tumors ◽  
Open Label ◽  
Phase 1 Study

TPS3157 Background: AGEN1181 is a novel Fc-optimized anti-CTLA4 antibody, currently being evaluated in an ongoing multi-center, open-label, phase 1 study in all advanced solid tumors as mono-therapy and combination with anti-PD-1 antibody, AGEN2034 (NCT03860272). AGEN1181 is Fc-engineered to harness a novel mechanism for enhanced FcγR-dependent functionality relative to first-generation CTLA-4 antibodies. In pre-clinical models, AGEN1181 enhances T cell priming, depletion of intratumoral regulatory T cells (Treg) and improved memory formation compared to first-generation anti-CTLA-4 antibodies. Most notably, AGEN1181 demonstrates improved binding to FcyRIIIA and superior T cell responsiveness in populations that only express the low affinity FcγRIIIA receptor relative to first-generation IgG1 CTLA-4 antibodies. The combination of AGEN1181 and AGEN2034 further enhances T cell activation and effector function. Methods: This phase 1 study is an open-label, multi-center dose-escalation designed to evaluate the safety, tolerability, dose limiting toxicity (DLT) PK, and pharmacodynamic profiles of patients with refractory advanced solid tumors who did not receive an anti-CTLA4 previously. The study is being conducted in 3 arms; with patients assigned using a standard 3+3 dose escalation design in the mono-therapy arms with AGEN1181 and an accelerated design in the combination with AGEN2034 arm. AGEN1181 is administered as IV infusion as mono-therapy on Day 1 of every 3 weeks (0.1,0.3,1,2,4 mg/kg), every 6-weeks (1,2,4 mg/kg) in parallel cohorts and every 6-weeks (0.1,0.3,1,2,4 mg/kg) in combination with AGEN2034 (3mg/kg Q2Weeks) until disease progression or unacceptable toxicity (maximum 2 years). All 3 Arms are open and enrolling patients. The study is expected to enroll approximately 80 evaluable patients with solid tumors. Dose reductions are not allowed in the event of AGEN1181-related toxicities. Currently 3 cohorts have been completed, first cohort in the combination arm and the fourth cohort in the monotherapy arm are enrolling. Preclinical and clinical assessment of AGEN1181 supports continued development as a potential therapy for refractory or relapsed advanced solid tumors. Clinical trial information: NCT03860272 .

scholarly journals 523 Preliminary clinical experience with XmAb20717, a PD-1 x CTLA-4 bispecific antibody, in patients with advanced solid tumors

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A553-A553
Author(s):  
Elaine Shum ◽  
Matthew Reilley ◽  
Yana Najjar ◽  
Adil Daud ◽  
John Thompson ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
T Cell ◽  
Solid Tumors ◽  
Dose Escalation ◽  
Bispecific Antibody ◽  
Objective Response ◽  
Checkpoint Blockade ◽  
List Type ◽  
Advanced Solid Tumors ◽  
Tumor Types

BackgroundXmAb20717 is a humanized bispecific monoclonal antibody that simultaneously targets PD-1 and CTLA-4. We report updated data on patients treated at the recommended expansion dose from an ongoing, multicenter, Phase 1, dose-escalation and -expansion study of intravenous XmAb20717 in patients with selected advanced solid tumors that progressed after treatment with all standard therapies or with no standard therapeutic options.MethodsA maximum tolerated dose was not reached in dose escalation. XmAb20717 10 mg/kg every 2 weeks (Q2W) was selected as the expansion dose, based on consistent T-cell proliferation in peripheral blood indicative of dual PD-1/CTLA-4 checkpoint blockade, and response to treatment (RECIST[1.1]).1 Parallel expansion cohorts included ~20 patients each with melanoma, renal cell carcinoma (RCC), non-small cell lung cancer (NSCLC), castration-resistant prostate cancer (CRPC), and a basket of tumor types without an FDA-approved checkpoint inhibitor (CI). Patients treated with 10 mg/kg in dose escalation were pooled with expansion cohorts for analysis of clinical activity and safety.ResultsAs of 9 June 2021, 110 patients, ranging in age from 39 to 89 years and 66.4% male, were treated, and 5 were continuing treatment. Patients had received a median of 4 prior systemic treatment regimens, including CI therapy for 64.5%. The objective response rate was 13.0% (10/77 patients evaluable for efficacy), including 1 complete response (melanoma [confirmed]) and 9 partial responses (confirmed: 1 melanoma, 2 RCC, 2 CRPC, 1 ovarian cancer; unconfirmed: 1 melanoma, 2 NSCLC). The CRPC responders (2/7 with RECIST-measurable disease) had confirmed PSA decreases ≥ 50% from baseline (to 0.02 and 0.3 ng/mL); neither had progression on bone scans. All responders had prior CI exposure, except those with CRPC. Robust CD4 and CD8 T-cell activation was seen. Low baseline tumoral expression of myeloid recruitment genes, including IL-8, was associated with clinical benefit. Grade ≥ 3 immunotherapy-related adverse events in ≥ 3 patients included rash (16.4%), transaminase elevations (9.1%), hyperglycemia (4.5%), acute kidney injury (3.6%), amylase and lipase increased (2.7%), and lipase increased (2.7%).ConclusionsPreliminary data indicate 10 mg/kg XmAb20717 Q2W was associated with complete and partial responses in multiple tumor types and was generally well-tolerated in these heavily pretreated patients with advanced cancer. Changes in T-cell populations in the periphery and tumor are consistent with robust dual checkpoint blockade. These findings support further development of XmAb20717 in advanced solid tumors, including metastatic prostate cancer.Trial RegistrationNCT03517488ReferencesShum E, Daud A, Reilley M, et al. Preliminary safety, pharmacokinetics/pharmacodynamics, and antitumor activity of XmAb20717, a PD-1 x CTLA-4 bispecific antibody, in patients with advanced solid tumors. JITC 2020;8(3):A247-8.Ethics ApprovalThe study was approved by each institution’s IRB.

A phase 1b, open-label, dose-escalation study to evaluate camidanlumab tesirine (Cami) as monotherapy in patients (pts) with advanced solid tumors.

2021 ◽  
Vol 39 (15_suppl) ◽  
pp. 2556-2556
Author(s):  
Igor Puzanov ◽  
Patricia LoRusso ◽  
Kyriakos P. Papadopoulos ◽  
Christopher T. Chen ◽  
Yvan LeBruchec ◽  
...  
Keyword(s):  
Antitumor Activity ◽  
Solid Tumors ◽  
Dose Escalation ◽  
Stable Disease ◽  
Single Agent ◽  
Treatment Withdrawal ◽  
Advanced Solid Tumors ◽  
Open Label ◽  
Phase 1B ◽  
Grade 3

2556 Background: Depletion of tumor-infiltrating CD25+ regulatory T cells (Tregs), which inhibit tumor-specific immune responses, could contribute to tumor eradication. Cami (ADCT-301), an anti-CD25, pyrrolobenzodiazepine-based antibody-drug conjugate, targets CD25+ Tregs. A mouse surrogate has shown potent antitumor activity in solid tumor models. Here we report preliminary data from the monotherapy arm of a phase 1b trial of Cami in pts with selected advanced solid tumors. Methods: The monotherapy dose-escalation part of this open-label study enrolled pts (aged ≥18 years) with selected advanced solid tumors and no suitable existing therapy. The primary objective was to characterize safety and tolerability, and to identify the recommended phase 2 dose of Cami monotherapy. Secondary and exploratory objectives included evaluation of preliminary antitumor activity, pharmacokinetics (PK), pharmacodynamics (PD), and immunogenicity. Pts received Cami every 3 weeks (1 cycle) with dose escalation per a 3+3 design. Disease control rate (DCR) was assessed (complete and partial responses [CR, PR] and stable disease). Results: At data cut-off (Dec 17, 2020), 44 pts were enrolled, with primary tumor types (stage IVA/B: 27 pts; 61.4%) of colorectal (15 pts; 34.1%), pancreatic (14 pts; 31.8%), head and neck, ovarian/fallopian tube, and renal cell carcinoma (all 3 pts; 6.8%), non-small cell lung cancer (2 pts; 4.5%), gastric, esophageal/GEJ, melanoma, and triple-negative breast cancer (each 1 pt; 2.3%). Median (range) age was 60.5 (33–82) years; median (range) number of prior systemic therapies was 4 (1–9). Pts received a median (range) of 2 (1–6) Cami cycles at doses of 20–150 µg/kg. Median (range) treatment duration was 22 (1–178) days. No dose-limiting toxicities were reported. The maximum tolerated dose (MTD) was not reached. All-grade treatment-emergent adverse events (TEAEs) in ≥20% pts were nausea (18 pts; 40.9%), decreased appetite and fatigue (each 16 pts; 36.4%), constipation (13 pts; 29.5%), abdominal pain (11 pts; 25%), and rash (10 pts; 22.7%). The only Grade ≥3 TEAE in ≥10% pts was anemia (5 pts; 11.4%). Grade 3 autoimmune AEs (colitis, immune-mediated AE, systemic inflammatory response syndrome) and neurologic AEs (dysphagia and asthenia, but not GBS) were reported in 3 (6.8%) and 2 (4.5%) pts, respectively. 1 (2.3%) Cami-related TEAE led to treatment withdrawal; no Cami-related TEAEs were fatal. DCR was 25% (95% CI: 11.1, 34.7); 11/44 pts attained stable disease. No pts had CR or PR. Conclusions: Dose escalation of Cami monotherapy is complete. The safety profile is encouraging and MTD was not reached. PK/PD data will be presented. 150 µg/kg is the highest dose investigated for single-agent Cami and the highest to be investigated combined with pembrolizumab in selected advanced solid tumors in the current protocol. Funding: ADC Therapeutics SA NCT03621982. Clinical trial information: NCT03621982.

A phase 1, multicenter, open-label, dose-escalation, safety, pharmacodynamic, pharmacokinetic study of Q702 with a cohort expansion at the RP2D in patients with advanced solid tumors.

2021 ◽  
Vol 39 (15_suppl) ◽  
pp. TPS2673-TPS2673
Author(s):  
Angela Tatiana Alistar ◽  
Anthony B. El-Khoueiry ◽  
Devalingam Mahalingam ◽  
Monica M. Mita ◽  
Hwankyu Kang ◽  
...  
Keyword(s):  
Solid Tumors ◽  
T Cell Activation ◽  
Pharmacokinetic Study ◽  
Dose Escalation ◽  
Cell Activation ◽  
Phase 1 ◽  
Innate Immune ◽  
Advanced Solid Tumors ◽  
Open Label ◽  
Label Dose

TPS2673 Background: Immune checkpoint inhibitors directly targeting T cell activation have been successfully used in the treatment of various malignancies, nevertheless, the durable ORRs are low for certain indications. The low ORRs have been attributed to the immune suppressive tumor microenvironment (TME), composed of innate immune suppressive components such as tumor associated macrophages (TAM) and myeloid-derived suppression cells (MDSC). The potential contributions of innate immune modulation to anti-tumor immunity, suggest the need for the novel strategies to elicit a more efficient/robust immune response against the targeted malignant cells. Axl, Mer and CSF1R receptor tyrosine kinases play vital roles in promoting an immune suppressive TME by affecting TAM and MDSC populations and by decreasing antigen presentation on tumor cells. Q702 is a novel Axl/Mer/CSF1R inhibitor, able to modulate the TAM and MDSC population leading to CD8+ T cell activation and to increase antigen presentation of the tumor cells in syngeneic animal models. Q702, as a monotherapy, shows significant tumor growth inhibition in multiple syngeneic tumor models, and demonstrates synergistic effects with anti-PD-1 treatment particularly in high myeloid containing tumor models. Interestingly, intermittent administration of Q702 monotherapy demonstrates a more favorable immune cell population changes, possibly through preventing immune exhaustion secondary to negative feedback with continuous activation. These results suggest that Q702 monotherapy or in combination with existing therapies have a good potential to become a novel treatment strategy for patients with advanced solid tumors. Methods: “A Phase 1, Multicenter, Open-label, Dose-Escalation, Safety, Pharmacodynamic, Pharmacokinetic Study of Q702 with a Cohort Expansion at the RP2D in Patients with Advanced Solid Tumors. (NCT04648254)” is open and recruiting patients at 4 US investigative sites. Patients with histologically or cytologically confirmed advanced or metastatic solid tumors, that have progressed following SOC or for which there is no SOC which confers clinical benefit are being enrolled in this study. The study follows a standard dose escalation. The study will enroll up to 78 patients. The primary endpoint is to establish safety, PK profile and define the recommended phase 2 dose. The secondary and exploratory endpoints include establishing pharmacokinetic/pharmacodynamic relationship, potential biomarkers and preliminary anti-tumor activity. Clinical trial information: NCT04648254.

A phase I study to evaluate the T-cell engager AMV564 alone and in combination with pembrolizumab in subjects with advanced solid tumors.

2020 ◽  
Vol 38 (15_suppl) ◽  
pp. 3101-3101
Author(s):  
Alexander Starodub ◽  
Sarina Anne Piha-Paul ◽  
Raghad Karim ◽  
Curtis Ruegg ◽  
Victoria Smith ◽  
...  
Keyword(s):  
Clinical Trial ◽  
T Cells ◽  
T Cell ◽  
Solid Tumors ◽  
T Cell Activation ◽  
Cell Activation ◽  
Gastroesophageal Junction ◽  
Effector Memory ◽  
Cytotoxic T Cell ◽  
Advanced Solid Tumors

3101 Background: Overcoming the immune-suppressive tumor environment induced by myeloid-derived suppressor cells (MDSC) is a major challenge in immune therapy. CD33 signaling in immature myeloid cells promotes expansion of MDSC and production of immune-suppressive factors. AMV564 is a bivalent, bispecific T-cell engager that binds CD3 and CD33. Preferential binding of AMV564 to areas of high CD33 density enables selective targeting of MDSC. Ex vivo data (Cheng 2017; Blood;130:51) and an ongoing clinical trial in acute myeloid leukemia (NCT03144245) demonstrate the ability of AMV564 to deplete MDSC while sparing monocytes and neutrophils. Methods: In this 3+3 dose escalation study, patients with advanced solid tumors receive AMV564 once daily via subcutaneous (SC) injection for 2 out of 3 wks per cycle, alone or in combination with pembrolizumab (200 mg every 3 wks). Key objectives are to evaluate AMV564 safety, identify a maximum tolerated or recommended phase 2 dose, and evaluate PK, immunophenotype of myeloid and T cell compartments, and preliminary efficacy. Results: Eleven patients have been enrolled: 8 monotherapy (3 at 15 mcg/d, 5 at 50 mcg/d) and 3 combination (5 mcg/d). Tumor types include ovarian (n = 2), small bowel, gastroesophageal junction, endometrial, rectal, penile, urothelial, squamous cell carcinoma (skin), appendiceal, and non-small cell lung. AMV564 was associated with grade (G) 1-2 injection site reactions and G1-2 fevers, which were manageable with acetaminophen and diphenhydramine, as well as G2 weight gain and G3 anemia. No dose-liming toxicity has been observed in any cohort. Three monotherapy patients (15 mcg/d) were evaluable for efficacy with ≥1 on-treatment scan; 2 had SD and 1 PD per RECIST 1.1 criteria. T cell activation, as shown by redistribution from the periphery (margination), was apparent in the first week of dosing for most patients. Compensatory myelopoiesis led to initial expansion of MDSC which were then depleted by AMV564. Increased cytotoxic T cell activation and T-helper (Th) 1 response was evidenced by increased T-bet positive CD4 and CD8 cells and controlled or decreased regulatory T cells. In some patients, effector memory CD8 cell populations (Tem and Temra) were expanded. Conclusions: AMV564 is safe and tolerable when administered SC at doses of 15 mcg/d alone and 5 mcg/d in combination with pembrolizumab. AMV564 depleted MDSC populations and altered T cell profiles consistent with activation of cytotoxic T cells and a Th1 response. Clinical trial information: NCT04128423 .

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