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TPS2701 Background: Mutations in KRAS and NRAS occur in one quarter of human solid tumors. The G12D allele is the most commonly occurring variant in pancreatic, colorectal, non-small cell lung, ovarian, biliary and gallbladder cancers. ELI-002 2P is an immunotherapeutic comprised of a lymph-node targeted amphiphile (AMP)-modified G12D and G12R mutant KRAS peptides together with an AMP-modified CpG oligonucleotide adjuvant. In preclinical models, ELI-002 demonstrated increased cytotoxic KRAS-specific T cells compared to non-lymph node targeted controls using the same peptide and adjuvant. Clinical evaluation of adoptively transferred KRAS-specific T cells demonstrated objective antitumor activity (Tran 2016). Circulating tumor (ctDNA) methodology permits identification of patients with minimal residual disease (MRD) following locoregional treatment. In MRD setting, immunotherapy is anticipated to succeed as the ratio of effector T cells to target tumor cells is maximized prior to bulk visible disease. The AMPLIFY-201 study (NCT04853017) is evaluating ELI-002 in patients with KRAS mutated solid tumors with MRD. Methods: AMPLIFY-201 is an open-label, dose-escalation and expansion phase I, first in human, trial evaluating ELI-002 2P in patients with KRAS mutated tumors with MRD following standard of care therapy. The initial phase I cohort enrolls patients with colorectal and pancreatic cancer to receive multiple doses of AMP-peptides 70mcg each (1.4 mg total) admixed with AMP-CpG 0.1 mg, administered once every two weeks. Subsequent phase I cohorts will enroll patients with RAS-mutated pancreatic, colorectal, non-small cell lung, ovarian, bile duct or gallbladder cancer, who will receive a fixed dose of AMP-peptides 70 mcg each, together with escalating doses of AMP-CpG. Safety and efficacy will be summarized with descriptive statistics. The maximum tolerated dose (if any) and the recommended phase II dose (RP2D) will be determined with the dose-response activity of ELI-002 2P in eliciting functional KRAS-specific T cells. Preliminary antitumor activity will be characterized using changes from baseline in ctDNA, serum biomarkers appropriate for tumor type, and progression free survival time. Eligibility includes patients who have received standard of care locoregional treatment according to NCCN guidelines and whom have MRD persistence or relapse (ctDNA positive). Patients with colon and pancreas cancer with Stage IV oligometastatic disease (< 3 lesions in one organ) rendered surgically free of disease and with MRD, are also eligible. The dose escalation portion of the study is currently enrolling. Clinical trial information: NCT04853017.

2553 Background: ORIC-101 is a potent and selective, orally bioavailable, small molecule antagonist of the glucocorticoid receptor (GR). Preclinical studies have demonstrated that activation of GR signaling leads to decreased responsiveness to chemotherapeutics (eg, taxanes) and antiandrogens across multiple tumor types. Mechanistically, ORIC-101 inhibits GR transcriptional activity and blocks the prosurvival signals mediated by the activated nuclear hormone receptor. Methods: A 3+3 dose escalation design was used to assess safety, pharmacokinetics (PK), pharmacodynamics (PD), and select the Recommended Phase 2 Dose (RP2D) of ORIC-101 in combination with nab-paclitaxel (nab-pac; NCT03928314). ORIC-101 doses ranging from 80 to 240 mg once daily, given either intermittently or in a continuous dosing regimen, were evaluated in combination with weekly nab-pac at 75 or 100 mg/m2. Plasma PK and PD biomarkers were assessed on day 1 and after repeat dosing. PD modulation in blood-derived peripheral blood mononuclear cells (PBMCs) was assessed by RT-qPCR for GR target genes. Antitumor activity was assessed by RECIST v1.1. Results: 21 patients with 10 different solid tumors, with and without a prior taxane, were treated in 5 cohorts. ORIC-101 exposure increased with dose, with no evidence for drug-drug interaction with nab-pac. In the initial cohort at 240 mg ORIC-101 and 100 mg/m2 nab-pac, 2 patients experienced dose limiting toxicities (DLTs) of Grade 3 fatigue and Grade 4 neutropenia/thrombocytopenia, respectively. No further DLTs were observed in subsequent cohorts and the RP2D was established as 160 mg ORIC-101 dosed once daily continuously for 21 days with nab-pac 75 mg/m2 given on days 1, 8, and 15 of each 28-day cycle, without requirement for prophylactic granulocyte colony-stimulating factor (G-CSF). The most common (> 15%), all grade treatment-related adverse events (AEs) were nausea (38%), diarrhea (33%), fatigue (29%), leukopenia (29%), neutropenia (29%), anemia (24%), and 19% of patients had increased liver function tests and alopecia. Biomarker data demonstrated ORIC-101-induced reduction in GR target gene expression in PBMCs, indicating PD modulation at all dose levels of ORIC-101. Preliminary antitumor activity was observed in 3 taxane-refractory patients with breast, endometrial, and pancreatic cancers. Conclusions: The combination of ORIC-101 and nab-paclitaxel demonstrated an acceptable tolerability profile and does not require prophylactic G-CSF. PK and PD showed no evidence of drug-drug-interaction and demonstrated GR target inhibition. Preliminary antitumor activity was observed in patients with solid tumors that previously progressed on a taxane-containing regimen. Dose expansion is ongoing at the RP2D in dedicated pancreatic, ovarian, triple negative breast cancers, and tissue-agnostic cohorts. Clinical trial information: NCT03928314.

2555 Background: Myeloid-derived suppressor cells (MDSC) contribute to an immunosuppressive tumor environment and are a barrier to immune therapy. CD33 signaling in immature myeloid cells promotes expansion of MDSC and production of immunosuppressive factors. AMV564 is a potent T cell engager that selectively depletes MDSC while promoting T cell activation and proliferation, via preferential binding to areas of high CD33 density. Methods: In this 3+3 dose escalation study, patients with relapsed/refractory solid tumors for whom no recognized standard therapy exists received AMV564 once daily via subcutaneous (SC) injection on Days 1-5 and 8-12 of a 21-day cycle, either alone or in combination with pembrolizumab (200 mg IV q3w). Study endpoints included incidence and severity of adverse events (AEs), pharmacokinetics (PK), and preliminary anti-tumor activity (using RECISTv1.1 criteria). Results: As of January 29, 2021, 20 patients were dosed in 3 monotherapy dose cohorts (15, 50, and 75 mcg/day), and 10 patients were dosed in 3 combination therapy cohorts (5, 15, and 50 mcg/day). Enrolled patients were: median age 64 years, 47% female, had received median 3.5 prior lines of therapy; 7 patients (35%) had received prior checkpoint inhibitor therapy (6 monotherapy patients, 1 combination therapy patient). No dose-limiting toxicity was observed and a maximum-tolerated dose was not reached in either the monotherapy or combination therapy cohorts. The most common treatment-related AEs (occurring in > 10% of patients, in order of decreasing frequency) in the monotherapy cohort were pyrexia, injection site reactions, fatigue, anemia, hypotension, pruritis, chills, and nausea. There were 2 cases of grade 2 cytokine release syndrome (CRS) at 75 mcg/day, both of which resolved after anti-IL6 therapy and study treatment was resumed. The most common treatment-related AEs in the combination cohorts (> 10% frequency) were injection site reaction, pyrexia, fatigue, pruritis, and anemia. No cases of CRS were noted in the combination cohorts. In preliminary PK analysis, estimated median plasma half-life for AMV564 after SC injection was > 48 hours, with dose-related increases in peak plasma concentration. Clinical responses were seen with monotherapy and combination therapy, including a complete response (CR) in a monotherapy-treated patient with ovarian cancer refractory to all standard therapies and anti-PD-1 therapy. Conclusions: AMV564 was well tolerated across multiple dose levels as monotherapy and in combination with pembrolizumab. Subcutaneous injection resulted in clinically relevant plasma exposures. Single-agent and combination therapy anti-tumor activity was observed. Further exploration of AMV564 clinical efficacy in expansion cohorts is ongoing. Clinical trial information: NCT04128423.

e14545 Background: BJ-001 is the first tumor-targeting Interleukin-15 (IL-15) fusion protein, composed of an integrin-binding Arg-Gly-Asp (RGD)-4C motif, linked with a human IgG1 Fc, and then a modified sushi domain of human IL-15Rα unit and a human IL-15. Tumor-targeting is achieved with RGD-4C motif which binds to αvβ3, αvβ5, and αvβ6 integrins, commonly overexpressed in solid tumors. The molecule has shown an ability to activate Natural Killer (NK) and T cells in vitro and in pre-clinical in vivo studies. Methods: This first in-human (FIH) study has 2 phases: Phase 1a and Phase 1b. Phase 1a consists of 3 parts. In all 3 parts patients receive escalating doses of BJ-001 as a once weekly subcutaneous injection for 4 weeks in 6-week cycles. Part 1 utilizes an accelerated dose escalation design with single patient cohort for the first 3 dose levels. Part 2 uses a 3+3 dose escalation design. Part 3 uses a 3+3 dose escalation of BJ-001 but in combination with a fixed-dose PD-(L)1 inhibitor. Dose escalation will proceed based on clinical safety and tolerability data observed during the Dose Limiting Toxicity (DLT) period, i.e., Cycle 1 Days 1 through 28 for Part 1 and Cycle 1 Days 1 through 42 for Parts 2 and 3. Adult patients (ECOG PS ≤ 2) with locally advanced or metastatic solid tumors refractory to or intolerant of all existing therapies are eligible for Phase 1a. Phase 1b will enroll cohorts of adult patients with selected solid tumors known to have high levels of integrin expression at the Maximum Tolerated Dose or Recommended Phase 2 Dose of BJ-001 in combination with a PD-(L)1 inhibitor, as identified in Phase 1a, Part 3. Results: As of Jan 31, 2021, 9 patients have received BJ-001 dosing as a single agent at 0.21 µg/kg (n = 1), 0.9 µg/kg (n = 1), 3 µg/kg (n = 1), 6 µg/kg (n = 3), or 10 µg/kg (n = 3) in Phase 1a Parts 1 and 2, wherein 7 patients, including 1 patient in the 10 µg/kg cohort, have completed the DLT period. Among these 7 patients, 2 (1 in 3 µg/kg and 1 in 6 µg/kg cohorts) have stable disease and are still receiving BJ-001 treatment beyond Cycle 1. The longest duration in the study, to date, is approximately 4 cycles (over 5 months). Treatment Emergent Adverse Events (TRAEs) include injection site reactions (6/7, Grade 1-2), anorexia (2/7, Grade 1-2), cytokine release syndrome (1/7, Grade 1, resolved in 1 day), and temporal wasting (1/7, Grade 1). The AEs did not result in dose interruption or dose level adjustment. No DLTs observed to date. With escalating doses, a trend of increased post-dose NK cell counts observed, whereas Regulatory T cell (Treg) counts remained stable. Conclusions: To date, BJ-001 is well tolerated up to 6 µg/kg. The safety evaluation for 10 µg/kg is ongoing. The observed NK and Treg cell profiles are consistent with known IL-15 biology. Clinical trial information: NCT04294576.

437 Background: DZB is an oral small-molecule FGFR1/2/3 kinase inhibitor, which demonstrated antitumor activity in preclinical and clinical studies (in cholangiocarcinoma patients [pts] with FGFR2-driven tumors and in FGFR1-3-driven urothelial cancer [UC] PDX models). In CSF1-stimulated mouse bone-marrow derived macrophages, DZB reduced CSF1R phosphorylation with a maximal effect similar to the selective CSF1R inhibitor BLZ945, suggesting DZB could have an effect on tumor-associated macrophage regulation. Thus, DZB+AZB is a rationale combination to be investigated in immunogenic and FGFR-driven tumors like UC. Methods: FIDES-02 is a multi-cohort open-label Phase 1b/2 study evaluating the effect of DZB as monotherapy and DZB+AZB in combination. To determine the RP2D of DZB+AZB, a total of 26 pts with UC (N = 4) and other solid tumors (N = 22), of whom 7 pts carried various FGFR genetic aberrations (GA), were enrolled at 2 dose levels (DL) (1200 mg AZB Q3W + 200 mg [DL1] / 300 mg [DL2] DZB QD) and treated until disease progression or unacceptable toxicity. Both DLs were divided into MTD (endpoint: dose-limiting toxicity [DLT] at D21) and expansion cohorts to investigate both acute and delayed adverse events (AEs) per CTCAE v5. Results: In the MTD cohorts of both DL1 (N = 7) and DL2 (N = 6) no DLTs were observed, and the DL1 and DL2 expansion cohorts subsequently enrolled 7 and 6 pts, respectively. The most frequent treatment-emergent AEs across both DLs were fatigue (31%), nausea (27%), diarrhea (23%), the most frequent laboratory abnormalities were increased ALT (58%), and AST (50%). Non-DLT grade (G) ≥ 3 treatment-related AEs (TRAE) across both DLs were G3 diarrhea (4%), G3 nausea (4%), G3 asthenia (4%), oral fungal infection (4%) and one case of immune-related G4 nephritis (4%). Dose interruptions / reductions and discontinuations due to TRAEs occurred in 19% and 8%, respectively. Pharmacokinetic analyses demonstrated that DZB exposure parameters and AZB serum concentrations in pts treated with DZB+AZB were similar to those assessed in pts under DZB / AZB monotherapy. At data cut-off, 2 of 14 (DL1) and 7 of 12 pts (DL2) were still on treatment. Median duration of treatment in DL1 was 9.7 weeks (range, 9-25), and best overall response per investigator assessment was SD in 4 of 10 efficacy-evaluable DL1 pts. DL2 efficacy analysis was uninformative at cutoff. The combination of 1200 mg AZB Q3W with both 200 mg and 300 mg QD DZB was found to be safe and tolerable. Conclusions: The combination of DZB+AZB is safe at both investigated DLs, the RP2D has been determined as 300 mg DZB QD+1200 mg AZB Q3W. DZB can be safely dosed at its monotherapy RP2D in this novel combination with AZB. The anti-tumor efficacy of DZB+AZB is currently being investigated in adequately designed cohorts of FIDES-02 with enrichment for UC pts with FGFR GA. Clinical trial information: NCT04045613.