A phase 1 study of PARP-inhibitor ABT-767 in advanced solid tumors with BRCA1/2 mutations and high-grade serous ovarian, fallopian tube, or primary peritoneal cancer

Purpose This phase 1 study examined safety, pharmacokinetics (PK), and efficacy of the poly(ADP-ribose) polymerase (PARP) inhibitor ABT-767 in patients with advanced solid tumors and BRCA1/2 mutations or with high-grade serous ovarian, fallopian tube, or primary peritoneal cancer. Methods Patients received ABT-767 monotherapy orally until disease progression or unacceptable toxicity. Dose was escalated from 20mg once daily to 500mg twice daily (BID). Dose-limiting toxicities, recommended phase 2 dose (RP2D), food effect, objective response rate, and biomarkers predicting response were determined. Results Ninety-three patients were treated with ABT-767; 80 had a primary diagnosis of ovarian cancer. ABT-767 demonstrated dose-proportional PK up to 500mg BID and half-life of 2h. Food had no effect on ABT-767 bioavailability. Most common grade 3/4 treatment-related adverse events were nausea, fatigue, decreased appetite, and anemia. Anemia showed dose-dependent increase. RP2D was 400mg BID. Objective response rate by RECIST 1.1 was 21% (17/80) in all evaluable patients and 20% (14/71) in evaluable patients with ovarian cancer. Response rate by RECIST 1.1 and/or CA-125 was 30% (24/80) in patients with ovarian cancer. Mutations in BRCA1 or BRCA2, homologous recombination deficiency (HRD), and platinum sensitivity were associated with tumor response. Median progression-free survival was longer for HRD positive (6.7months) versus HRD negative patients (1.8months) with ovarian cancer. Conclusions ABT-767 had an acceptable safety profile up to the established RP2D of 400mg BID and dose-proportional PK. Patients with BRCA1 or BRCA2 mutation, HRD positivity, and platinum sensitivity were more sensitive to ABT-767

A phase 1 study of PARP-inhibitor ABT-767 in advanced solid tumors with BRCA1/2 mutations and high-grade serous ovarian, fallopian tube, or primary peritoneal cancer

Purpose This phase 1 study examined safety, pharmacokinetics (PK), and efficacy of the poly(ADP-ribose) polymerase (PARP) inhibitor ABT-767 in patients with advanced solid tumors and BRCA1/2 mutations or with high-grade serous ovarian, fallopian tube, or primary peritoneal cancer. Methods Patients received ABT-767 monotherapy orally until disease progression or unacceptable toxicity. Dose was escalated from 20 mg once daily to 500 mg twice daily (BID). Dose-limiting toxicities, recommended phase 2 dose (RP2D), food effect, objective response rate, and biomarkers predicting response were determined. Results Ninety-three patients were treated with ABT-767; 80 had a primary diagnosis of ovarian cancer. ABT-767 demonstrated dose-proportional PK up to 500 mg BID and half-life of ~2 h. Food had no effect on ABT-767 bioavailability. Most common grade 3/4 treatment-related adverse events were nausea, fatigue, decreased appetite, and anemia. Anemia showed dose-dependent increase. RP2D was 400 mg BID. Objective response rate by RECIST 1.1 was 21% (17/80) in all evaluable patients and 20% (14/71) in evaluable patients with ovarian cancer. Response rate by RECIST 1.1 and/or CA-125 was 30% (24/80) in patients with ovarian cancer. Mutations in BRCA1 or BRCA2, homologous recombination deficiency (HRD), and platinum sensitivity were associated with tumor response. Median progression-free survival was longer for HRD positive (6.7 months) versus HRD negative patients (1.8 months) with ovarian cancer. Conclusions ABT-767 had an acceptable safety profile up to the established RP2D of 400 mg BID and dose-proportional PK. Patients with BRCA1 or BRCA2 mutation, HRD positivity, and platinum sensitivity were more sensitive to ABT-767

Co-Culture of Amphibian Adrenal Cells: A Model of Medullary Control of Corticosteroidogenesis

115 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1999.Chromaffin-adrenocortical cellular interactions have become recognized as an important component of adrenocortical regulation, however, the mechanisms by which chromaffin cells modulate adrenocortical function are not well understood. To study chromaffin-adrenocortical cellular interactions directly, we developed primary frog (Rana pipiens) adrenal co-cultures. In these co-cultures, chromaffin cells extend processes that project toward or onto adrenocortical cells, mimicking their organization in vivo and indicating a potential for interaction between the two cell types. Furthermore, cultured chromaffin cells secrete norepinephrine, epinephrine and serotonin and respond to carbamylcholine, potassium, and veratridine stimulation; adrenocortical cells secrete a1dosterone and corticosterone and retain ACTH-responsiveness. To test whether chromaffin cells affect adrenocortical steroidogenesis, we used veratridine to selectively activate chromaffin cells. Prolonged chromaffin cell activation (24--96 hr) using 50 muM veratridine increased the number of contacts between chromaffin and adrenocortical cells and increased corticosterone secretion on days 3 (950%), and 4 (350%). alpha 2- and beta1,2-adrenergic and dopaminergic antagonists decrease corticosterone and aldosterone secretion while alpha2- and beta1,2-adrenergic agonists increase steroid secretion, suggesting that catecholamines mediate chromaffin-adrenocortical cellular interactions via these adrenergic receptor subtypes. Adrenocortical cell Fos protein expression was increased by chromaffin cell activation with 2 mM carbamylcholine (37%) or 50 muM veratridine (25%), demonstrating that chromaffin cell activation affects adrenocortical cells at the transcriptional level. The dynamic behavior of chromaffin and adrenocortical cells was assessed using time lapse microscopy. The effects of chromaffin cell activation on chromaffin cell morphology were evident within 30 minutes of verutridine treatment and included the establishment of growth cones, varicosities and rounded soma. Additionally, significant neurite outgrowth and branching, most often toward adrenocortical cells, was routinely observed, in contrast to control cultures. In both control and veratridine-treated cultures, substantial migration of adrenocortical cells towards chromaffin cells occurred, suggesting the presence of a trophic factor originating in the neuronal cells. Our results provide further evidence for reciprocal interactions between chromaffin and adrenocortical cells that affect cellular differentiation and modulation of steroid secretion. Furthermore, chromaffin and adrenocortical cells show activity-related plasticity that is likely to be important during development and in maintaining homeostasis.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

CTNI-76. EFFICACY OF BRAF INHIBITOR PLIXORAFENIB (FORE8394) IN RECURRENT, PRIMARY CENTRAL NERVOUS SYSTEM TUMORS (PCNST)

Abstract Plixorafenib, a selective potent BRAFi, is uniquely designed to disrupt BRAF dimers and evade paradoxical MAPK pathway activation. Thus, it inhibits both V600 and non-V600 BRAF alterations and may be less prone to toxicities and resistance typical of approved BRAFi. An approved BRAFi, when used with MEKi, has ORR 33% with mDOR 13.6=months and ORR=50% with DOR of 6-29 months in V600+ HGG and LGG, respectively (dabrafenib US Prescribing Information, 2023). Phase 1/2a is a single-arm study (NCT02428712) in patients (n=113) with BRAF-altered advanced tumors to assess safety, PK, and efficacy of oral plixorafenib 900-3600 mg/day alone or with cobicistat (CYP3A4/P-gp inhibitor). Symptomatic TEAEs (rash, pyrexia, myalgia) were low grade and infrequent relative to approved BRAFi. This pre-specified analysis (31Mar2023) was in MAPKi-naïve adults with BRAFV600+ PCNST. 22 patients with PCNST received plixorafenib: 9 LGG, 1 glioneuronal tumor (LGG/GNT; 5 V600+), 12 HGG (10 V600+). Treatment-emergent AEs (TEAEs, ≥ 20%) were limited to LFT changes, G1 increased creatinine, fatigue, headache, and nausea. Only one G3 event (increased ALT) occurred at the RP2D (n=7) showing better tolerability than dabrafenib. 10 BRAFV600+ MAPKi-naïve adults with PCNST (median age 45 yrs, 6 females, 9 non-Hispanic) were efficacy evaluable: 6 HGG (4 glioblastoma, 1 epithelioid glioblastoma, 1 anaplastic astrocytoma); 4 LGG/GNT (1 each: ganglioglioma, pilocytic astrocytoma, xanthoastrocytoma, neuroepithelial tumor). Prior anti-cancer treatments included surgery (8/10), radiotherapy (8/10), and systemic therapy (8/10, including temozolomide [n=8], bevacizumab [n=2], carboplatin [n=1], dendritic cell vaccine [n=1]). 1 was treatment-naïve (unresectable; declined radiation/chemotherapy). ORR=60% (6/10) including HGG=67% (4/6), LGG/GNT=50% (2/4); median time to response=1.94 months; 4/6 responders with DOR > 9 months; mPFS=34.1 months; median follow-up=10.3 months; 4/10 ongoing. Plixorafenib has a benign safety profile and leads to a high ORR and durable response in MAPKi-naïve BRAFV600+ PCNST. A phase 2 study is ongoing to confirm these findings (NCT05503797)