Bastos, Bruno R.

Abstract Background GSK3β serine/threonine kinase regulates metabolism and glycogen biosynthesis. GSK3β overexpression promotes progression and resistance through NF-κB and p53 apoptotic pathways. GSK3β inhibits immunomodulation by downregulating PD-L1 and LAG-3 checkpoints and increasing NK and T-cell tumor killing. 9-ING-41, a small-molecule, selective GSK3β inhibitor, showed preclinical activity in chemo-resistant PDX glioblastoma models, including enhanced lomustine antitumor effect. Methods Refractory malignancies (n = 162) were treated with 9-ING-41 monotherapy (n = 65) or combined with 8 cytotoxic regimens after prior exposure (NCT03678883). Recurrent gliomas (n = 18) were treated with 9-ING-41 IV TIW q21day cycles at 3.3, 5, 9.3, 15 mg/kg, as monotherapy or combined with lomustine 30 mg/m² PO weekly q84day cycles. Primary objective was safety. Results RP2D of 15 mg/kg IV TIW was confirmed across all 9 regimens, no accentuated chemotherapy toxicity noted. Glioma subtypes included: 13 glioblastoma, 2 anaplastic astrocytomas, 1 anaplastic oligodendroglioma, 1 astrocytoma. Median age 52 (30–69) years; 6 female, 12 male; median ECOG 1 (0–2); median recurrences 3 (1–6). All received upfront radiation/temozolomide (18/18), plus salvage nitrosoureas (15/18), bevacizumab (8/18), TTFields (6/18), or immunotherapy (4/18). IDH/mutation(3/18); 1p19q/codeletion(1/18); MGMT/methylated(1/18). Four received 9-ING-41 monotherapy, 14 concurrent with lomustine. No severe toxicities were attributed to 9-ING-41, only mild vision changes (9/18, 50%), or infusion reactions (4/18, 22%). Lomustine-related toxicities: G3/4 thrombocytopenia (3/14, 21%), G1/2 fatigue (4/14, 28%). Median days on therapy was 55 (4–305); 1 partial response (>50%) was noted. Median OS was 5.5 (95% CI: 2.8–11.4) months and PFS-6 was 16.7%. Conclusion 9-ING-41 plus/minus lomustine is safe and warrants further study in glioma patients.

Abstract BACKGROUND GSK3β serine/threonine kinase regulates metabolism and glycogen biosynthesis. GSK3β overexpression promotes tumor progression and resistance through NF-κB and p53 apoptotic pathways. GSK3β inhibits immunomodulation by downregulating checkpoints, e.g. PD-L1 and LAG-3, and increasing NK and T-cell mediated tumor killing. 9-ING-41 is a small-molecule, potent, selective GSK3β inhibitor with preclinical activity. In chemoresistant PDX glioblastoma models, 9-ING-41 enhanced lomustine antitumor effect. METHODS Patients with refractory malignancies were treated with 9-ING-41 monotherapy (n=65) or combined with 8 cytotoxic regimens after prior exposure (n=162) in the first-in-human study (NCT03678883). The recurrent gliomas subset was treated with 9-ING-41 monotherapy IV TIW q21day cycles at 3.3, 5, 9.3, 15mg/kg, or combined with lomustine 30 mg/m² PO weekly q84day cycles. Primary objective was safety and tolerability. RESULTS An RP2D of 15mg/kg IV TIW was confirmed across all 9 regimens, no accentuation of chemotherapy toxicity noted. Of 18 glioma patients enrolled, 13 were glioblastoma, 2 anaplastic astrocytomas, 1 anaplastic oligodendroglioma, and 1 diffuse astrocytoma; 6 female, 12 male; median age 52 (30-69) years; median ECOG was 1 (0-2). All received initial radiation and temozolomide (18/18), prior salvage therapies included nitrosoureas (15/18), bevacizumab (8/18), TTFields (6/18), checkpoint inhibitor (4/18). Median recurrences 3 (1-6). NGS alterations included: IDH/wildtype (11), IDH/mutation(3); 1p19q/codeletion(10); MGMT/unmethylated(11), MGMT/methylated(1); EGFR/amplification(6), EGFR/v3mutation(3), TERT/mutation(6), PTEN/loss(3), NF1/rearrangement(2), ATRX/loss (2), TP53/mutation(4), CDKN2A/deletion(2), RB1/loss(1), PALB2/mutation(10). Four patients received 9-ING-41 monotherapy, 14 concurrently treated with lomustine. No SAEs or grade 3/4 AEs attributed to 9-ING-41 noted, only G1/2 vision changes (9/18, 50%), infusion reactions (4/18, 22%). Lomustine-related toxicities included G3/4 thrombocytopenia (3/14, 21%), and G1/2 fatigue (4/14, 28%). Median therapy duration was 55 (4-305); 1 partial response ( >50%) noted with 9-ING-41/lomustine. Median PFS and OS were 1.9 (0.3-11.1) and 6.0 (1.6-16.6) months, respectively. CONCLUSIONS 9-ING-41 plus/minus lomustine is safe and warrants further study in glioma patients.

2051 Background: GSK-3β, a serine/threonine kinase, is a key regulator of metabolism and glycogen biosynthesis. GSK-3β aberrant overexpression promotes tumor progression and chemotherapy resistance through NF-κB and p53-mediated apoptotic pathways. GSK-3β inhibition impacts immunomodulation through downregulation of checkpoints, such as PD-L1 and LAG-3, and increasing NK and T-cell mediated killing of tumor cells. 9-ING-41 is a small-molecule potent selective GSK-3β inhibitor with preclinical antitumor activity against several tumor types. In chemoresistant PDX models of glioblastoma (GBM), 9-ING-41 enhanced the antitumor effect of CCNU and CPT-11. Methods: In the first-in-human study (NCT03678883), patients (pts) with refractory malignancies received 9-ING-41 monotherapy (n = 65) or in combination with one of 8 cytotoxic regimens after prior treatment with the same chemotherapy (n = 162). We report the subset of pts with recurrent gliomas treated with 9-ING-41 monotherapy IV twice a week in 21-day cycles at different dose levels (3.3, 5, 9.3, 15mg/kg), or in combination with lomustine 30 mg/m² orally once weekly in 84-day cycles. Primary objective was safety and tolerability. Results: An RP2D of 15mg/kg IV was confirmed across all 9 regimens, no accentuation of chemotherapy-related toxicity noted. Of 18 glioma patients enrolled, 13 were GBM, 2 anaplastic astrocytomas, 1 diffuse astrocytoma, and 1 anaplastic oligodendroglioma. Four patients received single agent 9-ING-41, 14 treated concurrently with lomustine. Demographics: 6 female, 12 male; median age 52 (30-69) years; median ECOG was 1 (0-2). All received first-line radiation and temozolomide (18/18), prior therapies for recurrences included nitrosoureas (15/18), bevacizumab (8/18), TTFields (6/18), immune checkpoint inhibitor (4/18). Median recurrences 3 (1-6). Genomic alterations from available NGS reports included: IDH WT (11), IDH mutation (3), MGMT promoter unmethylated (11), MGMT promoter methylated (1), 1p19q co-deletion (10), EGFR amplification (6), EGFR v3 mutation (3), TERT promoter mutation (6), PTEN loss (3), NF1 rearrangement (2), ATRX loss (2), TP53 mutated (4), CDKN2A deletion (2), RB1 loss (1), PALB-2 mutation (10). No SAEs or grade 3/4 AEs attributed to 9-ING-41 were noted; AEs included G1/2 transient vision changes (9/18, 50%), infusion reactions (4/18, 22%). Side effects from lomustine included: G3/4 thrombocytopenia (3/14, 21%), and G1/2 fatigue (4/14, 28%). Best overall response: 1 minimal response (-43%) after 2 cycles of 9-ING-41 and lomustine. Median days on therapy was 55 (4-305), 4/18 (22%) were stable for 20 weeks or longer. Conclusions: These results show 9-ING-41 alone or in combination is safe and warrants further study in glioma patients. Clinical trial information: NCT03678883.

Uveal melanoma is a rare form of melanoma with particularly poor outcomes in the metastatic setting. In contrast with cutaneous melanoma, uveal melanoma lacks BRAF mutations and demonstrates very low response rates to immune-checkpoint blockade. Our objectives were to study the transcriptomics of metastatic uveal melanoma with the intent of assessing gene pathways and potential molecular characteristics that might be nominated for further exploration as therapeutic targets. We initially analyzed transcriptional data from The Cancer Genome Atlas suggesting PI3K/mTOR and glycolysis as well as IL6 associating with poor survival. From tumor samples collected in a prospective phase II trial (A091201), we performed a transcriptional analysis of human metastatic uveal melanoma observing a novel role for epithelial-mesenchymal transition associating with survival. Specifically, we nominate and describe initial functional validation of neuropillin-1 from uveal melanoma cells as associated with poor survival and as a mediator of proliferation and migration for uveal melanoma in vitro. These results immediately nominate potential next steps in clinical research for patients with metastatic uveal melanoma.

3507 Background: Overexpression of GSK-3β, a serine/threonine kinase, is associated with advanced stage malignancies, aggressive tumor growth, and chemotherapy resistance. 9-ING-41 is a GSK-3β inhibitor with significant broad spectrum pre-clinical antitumor activity, including chemotherapy-resistant models. This first-in-human study (NCT03678883) is evaluating the safety, pharmacokinetics (PK), and efficacy of 9-ING-41 monotherapy and in combination with chemotherapy in patients (pts) with refractory malignancies. Methods: 9-ING-41 is given intravenously (IV) twice-weekly as a single-agent (21-day cycle) or combined with gemcitabine, gemcitabine/nab-paclitaxel, carboplatin, carboplatin/paclitaxel, doxorubicin, lomustine or irinotecan in patients previously treated with the same chemotherapy. Results: As of Jan 2020, 101 pts were enrolled. Tumor types: 25 pancreatic (PDAC), 14 colorectal (CRC), 10 non-small cell lung cancer (NSCLC), 8 GBM and other gliomas, 7 melanoma, 5 appendiceal, 4 breast (BC), 30 others. Seven single agent dose levels (DL) completed (1, 2, 3.3, 5, 7, 9.3, 12.4 mg/kg) without any 9-ING-41-attributable SAEs. 9-ING-41 attributable AEs include: transient visual change (color perception; n = 29), starting at DL 3 (3.3mg/kg), all G1/2; infusion reactions (n = 14), all G1/2, starting at DL 5 (7mg/kg). 9-ING-41’s mean terminal half-life is 12-20 hrs. Cmax and AUC0-72, are dose proportional with no accumulation. One BRAFV600K-mutated melanoma with > 20 brain metastases, post checkpoint/BRAF/MEK failure has an ongoing CR starting at cycle 2 and sustained after 9 months on treatment. 32 (31%) pts had SD as best response (6 PDAC, 6 CRC, 3 appendiceal, 2 BC, 2 salivary gland, 2 melanoma, 1 Merkel cell, 2 GBM/glioma, 1 RCC, 1 HCC, 1 NSCLC, 1 esophageal, 1 parotid gland, 1 nasopharyngeal, 1 peritoneal, 1 T cell-ALL). 8 pts remained on study treatment > 5 months (1 melanoma, 3 PDAC, 1 appendiceal, 1 GBM, 1 peritoneal, 1 salivary gland) with median treatment duration of 198 days (range 163-261). 32 pts continue to receive 9-ING-41. Conclusions: 9-ING-41 has dose-proportional PK, is well tolerated with significant antitumor activity as monotherapy and in combination with chemotherapy in pts with refractory tumors. 1 ongoing CR was observed in a refractory BRAF-mutated melanoma. A biologically active dose has been reached, although MTD has not been determined. Enrollment is ongoing. Clinical trial information: NCT03678883 .

Abstract Purpose: The surface receptor MET is highly expressed on primary uveal melanoma; MET inhibitors demonstrated early clinical signals of efficacy in slowing uveal melanoma growth. The primary objective of our study was to compare the progression-free survival rate at 4 months (PFS4) of patients with uveal melanoma treated with cabozantinib or chemotherapy. Patients and Methods: Patients with metastatic uveal melanoma and RECIST measurable disease were randomized 2:1 to receive either cabozantinib (arm 1) versus temozolomide or dacarbazine (arm 2) with restaging imaging every two cycles. Cross-over from arm 2 to cabozantinib after progression was allowed (arm 2X). Available tumor specimens were analyzed by whole-exome sequencing (WES) and results were correlated with outcome. Results: Forty-six eligible patients were accrued with 31, 15, and 9 in arms 1, 2, and 2X, respectively. Median lines of prior therapy, including hepatic embolization, were two. Rates of PFS4 in arm 1 and arm 2 were 32.3% and 26.7% (P = 0.35), respectively, with median PFS time of 60 and 59 days (P = 0.964; HR = 0.99). Median overall survival (OS) was 6.4 months and 7.3 months (P = 0.580; HR = 1.21), respectively. Grade 3–4 Common Terminology Criteria for Adverse Events were present in 61.3%, 46.7%, and 37.5% in arms 1, 2, and 2X, respectively. WES demonstrated a mean tumor mutational burden of 1.53 mutations/Mb and did not separate OS ≤ or >1 year (P = 0.14). Known mutations were identified by WES and novel mutations were nominated. Conclusions: MET/VEGFR blockade with cabozantinib demonstrated no improvement in PFS but an increase in toxicity relative to temozolomide/dacarbazine in metastatic uveal melanoma.

9506 Background: Survival is poor in mUM and treatment options are limited. MET kinase is over-expressed on UM and the MET inhibitor cabo showed activity in an early trial. Methods: A091201 was a 2:1 randomized phase II study testing progression-free survival (PFS) of cabo (60 mg daily) vs chemo (DTIC/TMZ). We studied baseline metastatic tumor samples (n = 19; 1 lung, 18 liver) by whole exome sequencing (WES) and RNAseq. We correlated data with OS and made comparisons for mUM vs. primary tumors from TCGA (n = 80). Results: 46 patients were accrued with 96% and 63% with liver metastases and elevated LDH, respectively. Toxicities were similar to prior reports of cabo and chemo. The trial stopped at interim analysis due to no difference in PFS (p = 0.964; HR = 0.99) or OS (p = 0.580; HR = 1.21). WES showed tumor mutational burden of 46±4 (mean±SEM) and did not separate OS at 1 year (p = 0.14, two-sided Wilcoxon rank sum test) in A091201. Recurrent known mutations included GNAQ/11, SF3B1, BAP1; novel mutations included GOLGA6L10, PKD1L3, and FAM228B. Gene expression signatures differed significantly between A091201 and TCGA cohorts including MET signaling (p = 7.87e-22), T cell-inflamed (p = 0.004), homologous recombination deficiency (p = 0.004), proliferation (p = 0.009) and hypoxia (p = 5.2e-10) (two-sided Student’s t-test). Tumor immune cell enrichment analysis revealed significant differences with lower M1:M2 macrophage (p = 1.2e-10) and higher Tregs (p = 6.0E-21) in mUM relative to TCGA (two-sided Wilcoxon rank sum test). Epithelial-mesenchymal transition gene expression signature was significantly associated with worse OS in A091201 (p = 0.02) with angiogenesis signature trending toward significance (p = 0.21) (log-rank test). OS separated by differentially expressed genes with OS ≤ 1 year associating with increased expression of the angiogenesis/immune-associated molecule neuropilin 1. Conclusions: These results provide insights between primary and mUM indicating potential novel therapeutic approaches. Support: U10CA180821, U10CA180882, T32GM007019, Exelixis. https://acknowledgments.alliancefound.org ; Clinical trial information: NCT01835145.