Houvras, Yariv

TPS3164 Background: TUB-030 is a novel antibody-drug conjugate (ADC) targeting 5T4, an oncofetal antigen expressed in various solid tumors with limited expression in healthy tissues. TUB-030 leverages optimized biophysical properties, an effector-silenced antibody, and an exatecan payload to maximize the therapeutic index and minimize off-target toxicities. Preclinical studies demonstrated potent anti-tumor activity, including long-lasting tumor regression at doses as low as 1 mg/kg and durable responses even in tumors with low 5T4 expression. Methods: 5-STAR 1-01 is a multicenter, first-in-human dose escalation and dose optimization Phase I/IIa clinical trial designed to investigate safety, tolerability, pharmacokinetics (PK), and efficacy of the anti-5T4 ADC TUB-030 in patients with advanced and metastatic solid tumors. Eligible patients have one of the following tumor types: head and neck squamous cell carcinomas (HNSCC), non-small-cell lung cancer (NSCLC), small cell lung cancer, pleural mesothelioma, triple-negative breast cancer, HR+/HER2- breast cancer, esophageal cancer, gastric cancer, pancreatic adenocarcinoma, colorectal cancer, bladder cancer, prostate cancer, cervical cancer, osteosarcoma, or soft tissue sarcomas and must have exhausted available standard-of-care therapies. Phase I is an open-label, single-arm dose escalation trial, with administration every 21 days. Dose escalation follows an accelerated titration design (ATD) transitioning to Bayesian optimal interval (BOIN) upon predefined toxicity thresholds. Backfill cohorts are planned in NSCLC and HNSCC to further evaluate the safety and efficacy profile at, or near, the maximum tolerated dose (MTD). Primary endpoints include safety and tolerability of TUB-030 as monotherapy, determination of the MTD and the recommended phase II doses; secondary endpoints assess pharmacokinetics, immunogenicity, and preliminary clinical activity using RECIST v1.1 criteria. Exploratory endpoints include analysis of circulating tumor DNA. In phase IIa, dose-optimization will evaluate two dose levels in select indications in order to identify the optimal dose for further development. Enrollment of approximately 130 patients across the US and Canada is planned, with dose escalation currently underway. This study investigates TUB-030, a novel 5T4 targeted ADC as a therapy for advanced/metastatic solid tumors. Clinical trial information: NCT06657222 .

e23309 Background: BCMA-directed T-cell–engaging therapies have been introduced into clinical practice for the treatment of TCE RRMM. While efficacious, such treatments are associated with safety considerations such as cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), and serious infections. These treatments also vary in reported efficacy, administration processes, and hospitalization requirements. The aim of this study is to quantify patient preferences and tradeoffs regarding these attributes. Methods: A discrete choice experiment (DCE) was designed to elicit preference weights corresponding to seven attributes related to efficacy (objective response rate [ORR], overall survival [OS]), safety (all-grade CRS, all-grade ICANS, serious infections) and treatment procedures (treatment administration, hospitalization requirements). Attribute levels were based on plausible ranges of potential values. Patients in the United States (US) with a physician-confirmed diagnosis of TCE RRMM were recruited. Pre-test interviews with patients were conducted and the final survey deployed online in 2023. A random-parameters logit model was used to estimate preference weights. Conditional relative importance (CRI) was calculated to rank the relative importance of each attribute. The minimum acceptable benefit (MAB) and maximum acceptable risk (MAR) were calculated to estimate the tradeoffs between efficacy and safety attributes. Results: The sample included 200 respondents (mean [standard deviation] age: 61 [6.4] years; 43% female; 46% White; 10% African American). A total of 197 participants reported having responded to prior treatment, of whom 195 had relapsed or become refractory. In the DCE, a 24-month increase in OS was found to be the most important attribute, with a CRI of 32.0%. Next most important were avoiding a 60% risk of serious infection (CRI 17.3%), avoiding 14-day hospitalization requirements (CRI 15.0%), and a 38% increase in ORR (CRI 13.7%). A treatment that could be started immediately and administered weekly or up to every 4 weeks was preferred over a CAR T-like procedure with a waiting period. Fewer initial hospitalization days was significantly preferred over more hospitalization days. The MABs for OS when the risk of serious infection was increased from 20% to 60%, CRS from 40% to 95%, and ICANS from 3% to 20% were 24.2, 17.1, and 18.0 months, respectively. When OS was increased from 12 to 36 months, the estimated MARs for serious infections, CRS, and ICANS were > 60%, > 95%, and > 20%, respectively. Conclusions: This study highlights US patient preferences regarding treatment attributes for TCE RRMM. Treatment benefits and risks and the mutual tradeoffs considered by patients should be evaluated when developing and selecting therapeutic approaches.

Background As therapeutic advances have increased life expectancy for patients (pts) with relapsed/refractory (RR) multiple myeloma (MM), second primary malignancies (SPMs) have become an increasingly important safety consideration. Prior studies have demonstrated that treatment with alkylators, autologous stem cell transplantation, and immunomodulatory drugs (IMiDs), specifically lenalidomide, are associated with increased risk of SPM. Pts who are triple-class exposed (TCE), defined as prior exposure to an IMiD, a proteasome inhibitor (PI), and an anti-CD38 monoclonal antibody (mAb), represent an increasingly large subgroup of RRMM pts. The objective of this study was to describe the incidence and characteristics of SPMs in Medicare-insured pts with TCE RRMM initiating a new line of therapy (LOT). Methods Adult pts with an incident diagnosis (Dx) of MM (≥2 outpatient Dx 30-365 days apart OR ≥1 inpatient Dx AND 6 months of continuous eligibility prior to initial Dx) during the study period (Nov 14, 2006-Dec 31, 2020) who were TCE (≥1 claim each for an IMiD, a PI, and an anti-CD38 mAb) were selected from the Center for Medicare and Medicaid Services Chronic Conditions Data Warehouse (TCE pts were assumed to have RRMM based on exposure). The first LOT after TCE was defined as the index LOT and the associated date of initiation was defined as the index date. Pts with SPMs prior to the index date were excluded. SPMs were identified based on having ≥2 outpatient Dx of SPM (of the same cancer type) 30-365 days apart OR ≥1 inpatient Dx of SPM. Dx of SPM included Dx of invasive malignancies or myelodysplastic syndromes (MDS), excluding MM, Waldenström macroglobulinemia, plasma cell leukemia, non-melanoma skin cancers, or primary bone malignancies that were preceded by a Dx of bone metastases. The incidence of SPM was calculated per 100 person years (PY) of follow-up, considering only the first SPM for each pt. Cumulative incidence of SPM (with death as a competing risk) was also calculated. For pts who experienced SPM, overall survival (OS) and measures of healthcare resource utilization (HRU) and costs (in 2021 USD, on a per patient per month [PPPM] basis) were calculated. Results A total of 3,088 TCE RRMM pts were identified, of whom 989 had no evidence of SPM prior to the index date (Table). These 989 pts had a mean age of 75.2 years, a mean of 2.9 prior LOTs and a mean of 3.1 years since MM Dx. Over a median follow-up of 7.1 months, 166 pts (19.3 per 100 PY) experienced an SPM, including 93 (10.8 per 100 PY) with a solid tumor and 73 (8.5 per 100 PY) with a hematologic malignancy. The latter included 27 (3.1 per 100 PY) with acute myeloid leukemia (AML) and 18 (2.1 per 100 PY) with MDS. The cumulative incidence of SPM (95% confidence interval [CI]) at 12, 24, and 36 months was 15.2% (12.8-17.9%), 19.7% (16.8-22.8%), and 23.8% (20.2-27.6%), respectively (Figure). Median (95% CI) OS from SPM Dx was 7.9 months (5.4-10.9). Kaplan-Meier estimated probability of survival (95% CI) at 12, 24, and 36 months following SPM Dx was 40.3% (31.6-48.9%), 27.6% (18.6-37.4%), and 9.5% (2.1-23.8%), respectively. Mean (95% CI) total costs after SPM were $22,514 ($19,105-$26,404) PPPM. Conclusions The incidence of SPM in Medicare-insured TCE RRMM pts is high. Many SPMs in these pts, such as AML, are life-threatening and may interfere with or prevent MM treatment. Pts with SPMs have poor survival and high HRU and costs. With increasing OS for RRMM pts due to therapeutic advancements, there is a need for effective treatments that are not associated with increased risk of SPMs.

Abstract Hepatic cysts are fluid‐filled lesions in the liver that are estimated to occur in 5% of the population. They may cause hepatomegaly and abdominal pain. Progression to secondary fibrosis, cirrhosis, or cholangiocarcinoma can lead to morbidity and mortality. Previous studies of patients and rodent models have associated hepatic cyst formation with increased proliferation and fluid secretion in cholangiocytes, which are partially due to impaired primary cilia. Congenital hepatic cysts are thought to originate from faulty bile duct development, but the underlying mechanisms are not fully understood. In a forward genetic screen, we identified a zebrafish mutant that developed hepatic cysts during larval stages. The cyst formation was not due to changes in biliary cell proliferation, bile secretion, or impairment of primary cilia. Instead, time‐lapse live imaging data showed that the mutant biliary cells failed to form interconnecting bile ducts because of defects in motility and protrusive activity. Accordingly, immunostaining revealed a disorganized actin and microtubule cytoskeleton in the mutant biliary cells. By whole‐genome sequencing, we determined that the cystic phenotype in the mutant was caused by a missense mutation in the furinb gene, which encodes a proprotein convertase. The mutation altered Furinb localization and caused endoplasmic reticulum (ER) stress. The cystic phenotype could be suppressed by treatment with the ER stress inhibitor 4‐phenylbutyric acid and exacerbated by treatment with the ER stress inducer tunicamycin. The mutant liver also exhibited increased mammalian target of rapamycin (mTOR) signaling. Treatment with mTOR inhibitors halted cyst formation at least partially through reducing ER stress. Conclusion : Our study has established a vertebrate model for studying hepatic cystogenesis and illustrated the contribution of ER stress in the disease pathogenesis.

9089 Background: RET fusions are targetable oncogenic drivers in 1–2% of non-small cell lung cancer (NSCLC). ARROW (NCT03037385) supported the US FDA approval of pralsetinib, a highly potent oral selective RET inhibitor for RET-altered NSCLC and thyroid cancer. Here, we present updated results for a larger population of patients with RET fusion–positive NSCLC enrolled in ARROW. Methods: ARROW is a phase 1/2 open-label study conducted at 84 sites in 13 countries. Phase 2 expansion cohorts included patients with RET fusion–positive NSCLC. Initially, all treatment-naïve patients were not candidates for platinum-based therapy, a requirement removed by protocol amendment in July 2019. Primary objectives are overall response rate (ORR; blinded independent central review [BICR] per RECIST v1.1), assessed for patients with baseline measurable disease, and safety. Results: Updated analyses were completed as of Nov 6, 2020 (data cut-off), for patients who initiated pralsetinib 400 mg QD by May 22, 2020 (enrollment cut-off). Efficacy results, including analyses for treatment-naïve patients enrolled after eligibility criteria were revised to allow candidates for platinum-based therapy, are shown in the Table. Conclusions: Pralsetinib showed rapid, potent, and durable clinical activity in patients with RET fusion-positive NSCLC (regardless of prior therapies), including poor prognosis patients not eligible for platinum-based therapy. Overall, pralsetinib was well-tolerated. These data highlight the need for RET testing early in the course of disease to identify candidates who may benefit from treatment with pralsetinib. Clinical trial information: NCT03037385. [Table: see text]

Abstract Background: Stage IVC (metastatic) anaplastic thyroid cancer (ATC) has a median overall survival (OS) of only 1.9 months. Single agent paclitaxel has modest activity in ATC. In pre-clinical studies, CS-7017 inhibited ATC proliferation through a novel mechanism–activation of PPAR-γ, followed by sequential upregulation of RhoB, then p21. Moreover, CS-7017 augmented the proapoptotic effects of paclitaxel. Based on these results, a multicenter study was conducted to determine if CS-7017+paclitaxel might prove safe and effective in advanced ATC. Design: A Phase 1 study was conducted to determine the Phase 2 dose. In Phase 1, patients received CS-7017 orally BID for one week (run-in phase), followed by a 3 h iv infusion of paclitaxel (175 mg/m2) every 3 weeks in combination with BID CS-7017. CS-7017 doses were escalated (0.15, 0.3, or 0.5 mg). Tissue biopsies were obtained at baseline and at one and three weeks for immunohistochemistry of PPAR-γ responsive proteins; serum CS-7017 PK studies were also performed. Results: Nineteen patients were enrolled, but 4 were not dosed (3 due to progression, 1 ineligible). Seven participated in CS-7017 dose levels 1a/1b (0.15 mg BID), six in dose level 2 (0.3 mg BID), and two in dose level 3 (run-in phase only–0.5 mg BID). Demographics: Of the 15 treated patients, 10 (67%) were women. Median age was 59 years (range: 43-82) Efficacy: Of 15 patients receiving drug, one had a confirmed partial response (PR) lasting from Day 69 to Day 175, and eight had stable disease (SD) as their best response. Median Time to Progression in 7 patients at Dose Level 1 was 49 days, but 70 days in Dose Level 2 (43% prolongation); corresponding median survival was 99 (0.15 mg BID) vs. 140 days (0.3 mg BID, 42% increase). Median peak CS-7017 blood level was 8.6 ng/mL (range: 5.1 to 13.7) for Level 1 and 22.0 ng/mL (17.0 to 31.5) for Dose Level 2. Adverse Events: Ten patients had AEs ≥ Grade 3, with two (anemia and localized edema) related to CS-7017. Thirteen events of fluid retention/edema were reported in 8 patients, with only 2 events of CTCAE grade ≥ 3. Eight patients had ≥ one SAE, with one (anemia) due to CS-7017. One SAE (anaphylactic reaction) was related to paclitaxel. No dose limiting toxicity was observed. Immunohistochemistry: Biopsies were available on 7 patients. PPAR-γ, RXR-α, RhoB were present in all; Angiopoietin-like 4 was induced by CS-7017. Conclusions: Combination therapy with CS-7017 and paclitaxel was tolerated and has biologic activity in patients with metastatic anaplastic thyroid carcinoma, with initial exploratory data suggesting a dose-dependent improvement in time to progression and survival in response to escalating CS-7017 dosage. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1278. doi:10.1158/1538-7445.AM2011-1278