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PURPOSE Adagrasib, a KRAS G12C inhibitor, has demonstrated clinical activity in patients with KRAS G12C -mutated non–small-cell lung cancer (NSCLC) and colorectal cancer (CRC). KRAS G12C mutations occur rarely in other solid tumor types. We report evaluation of the clinical activity and safety of adagrasib in patients with other solid tumors harboring a KRAS G12C mutation. METHODS In this phase II cohort of the KRYSTAL-1 study (ClinicalTrials.gov identifier: NCT03785249 ; phase Ib cohort), we evaluated adagrasib (600 mg orally twice daily) in patients with KRAS G12C -mutated advanced solid tumors (excluding NSCLC and CRC). The primary end point was objective response rate. Secondary end points included duration of response, progression-free survival (PFS), overall survival, and safety. RESULTS As of October 1, 2022, 64 patients with KRAS G12C -mutated solid tumors were enrolled and 63 patients treated (median follow-up, 16.8 months). The median number of prior lines of systemic therapy was 2. Among 57 patients with measurable disease at baseline, objective responses were observed in 20 (35.1%) patients (all partial responses), including 7/21 (33.3%) responses in pancreatic and 5/12 (41.7%) in biliary tract cancers. The median duration of response was 5.3 months (95% CI, 2.8 to 7.3) and median PFS was 7.4 months (95% CI, 5.3 to 8.6). Treatment-related adverse events (TRAEs) of any grade were observed in 96.8% of patients and grade 3-4 in 27.0%; there were no grade 5 TRAEs. TRAEs did not lead to treatment discontinuation in any patients. CONCLUSION Adagrasib demonstrates encouraging clinical activity and is well tolerated in this rare cohort of pretreated patients with KRAS G12C -mutated solid tumors.

425082 Background: KRAS, a mediator of signalling pathways essential for cellular growth, proliferation, and survival, is the most frequently mutated oncogene in cancer. Notably, KRAS mutations occur in ~90% of pancreatic cancers, of which ~2% are KRASG12C mutations. Other gastrointestinal (GI) tumors also harbor KRASG12C mutations, such as biliary tract cancer (BTC; 1%) and appendiceal cancer (3–4%), and they are also seen in non-GI tumors, such as endometrial and ovarian cancer (1–2%). Adagrasib, a covalent KRASG12C inhibitor that irreversibly and selectively binds KRASG12C in its inactive state, was selected for favorable properties, including long half-life (23 h), dose-dependent pharmacokinetics, and central nervous system penetration. Methods: KRYSTAL-1 is a multicohort phase 1/2 study (NCT03785249) evaluating adagrasib in patients (pts) with advanced solid tumors harboring a KRASG12C mutation. Here we report data from a phase 2 cohort evaluating adagrasib monotherapy administered orally at 600 mg BID in pts with unresectable or metastatic KRASG12C-mutated solid tumors (excluding non-small cell lung cancer and colorectal cancer), including pancreatic ductal adenocarcinoma (PDAC), BTC, other GI, and non-GI tumors. Study objectives include evaluation of clinical activity (ORR, DCR, DOR, PFS, OS) and safety. Results: As of October 1, 2022, 64 pts with KRASG12C-mutated solid tumors were enrolled and 63 were treated with adagrasib (median follow-up, 16.8 months); of these, 21 pts had PDAC, 12 BTC, 16 other GI tumors (9 appendiceal, 4 gastro-esophageal junction/esophageal, 3 small bowel), and 14 non-GI tumors (5 ovarian, 4 unknown primary, 3 endometrial, 1 breast, 1 glioblastoma). Overall, median age was 65 years, 61% had ECOG PS 1, and median prior lines of systemic therapy was 2. Among 57 pts with measurable disease (blinded independent central review), ORR was 35.1% (20/57; all partial responses); DCR was 86.0% (49/57); median DOR was 5.3 months (n=20; 95% CI 2.8–7.3); median PFS was 7.4 months (95% CI 5.3–8.6); and median OS was 14.0 months (n=64; 95% CI 8.5–18.6). Among 21 pts with PDAC, ORR was 33.3% (7/21); DCR was 81.0% (17/21); median PFS was 5.4 months (95% CI 3.9–8.2); and median OS was 8.0 months (95% CI 5.2–11.8). Among 12 pts with BTC, ORR was 41.7% (5/12); DCR was 91.7% (11/12); median PFS was 8.6 months (95% CI 2.7–11.3); and median OS was 15.1 months (95% CI 8.6–not estimable). Overall (n=63), treatment-related adverse events (TRAEs) of any grade were observed in 96.8% of pts (most commonly [≥20%] nausea [49.2%], diarrhea [47.6%], fatigue [41.3%], vomiting [39.7%]), grade 3 TRAEs in 25.4%, and grade 4 TRAEs in 1.6%. No grade 5 TRAE occurred. Conclusions: Adagrasib is well tolerated and demonstrates promising clinical activity in pretreated pts with PDAC, BTC, and other solid tumors harboring a KRASG12C mutation. Clinical trial information: NCT03785249 .

AbstractBackgroundThe accuracy of the eighth AJCC ypTNM staging system on the prognosis of gastric cancer (GC) patients after neoadjuvant therapy (NAT) is controversial. This study aimed to develop and validate a novel staging system using the log odds of positive lymph nodes scheme (LODDS).MethodsA retrospective analysis of 606 GC patients who underwent radical gastrectomy after neoadjuvant therapy was conducted as the development cohort. (Fujian Medical University Affiliated Union Hospital (n = 183), Qinghai University Affiliated Hospital (n = 169), Mayo Clinic (n = 236), Lanzhou University First Hospital (n = 18)). The validation cohort came from the SEER database (n = 1701). A novel ypTLoddsS (ypTLM) staging system was established using the 3‐year overall survival. The predictive performance of two systems was compared. ResultsTwo‐step multivariate Cox regression analysis in both cohorts showed that ypTLM was an independent predictor of overall survival of GC patients after neoadjuvant therapy (HR: 1.57, 95% CI: 1.30–1.88, p < 0.001). In the development cohort, ypTLM had better discrimination ability than ypTNM (C‐index: 0.663 vs 0.633, p < 0.001), better prediction homogeneity (LR: 97.7 vs. 70.9), and better prediction accuracy (BIC: 3067.01 vs 3093.82; NRI: 0.36). In the validation cohort, ypTLM had a better prognostic predictive ability (C‐index: 0.614 vs 0.588, p < 0.001; LR: 11,909.05 vs. 11,975.75; BIC: 13,263.71 vs 13,328.24; NRI: 0.22). The time‐dependent ROC curve shows that the predictive performance of ypTLM is better than ypTNM, and the analysis of the decision curve shows that ypTLM achieved better net benefits. ConclusionA LODDS‐based ypTLM staging system based on multicenter data was established and validated. The predictive performance was superior to the eighth AJCC ypTNM staging system.

Cancer stem cells (CSC) within non–small cell lung carcinoma (NSCLC) tumors drive NSCLC progression, metastasis, relapse, and intrinsic chemoresistance. Understanding the mechanisms that support the malignant phenotypes of NSCLC CSCs may provide insights for improved NSCLC therapeutic interventions. Here, we report that expression of RAB27B, a small GTPase, is significantly upregulated in NSCLC CSCs when compared with bulk cancer cells (BCC). Short hairpin RNA–mediated knockdown of RAB27B leads to a loss of stem cell marker gene expression and reduced NSCLC spheroid growth, clonal expansion, transformed growth, invasion, and tumorigenicity. We find that NSCLC CSCs secrete significantly more extracellular vesicles (EV) than BCCs, and that this is RAB27B-dependent. Furthermore, CSC-derived EVs, but not BCC-derived EVs, induce spheroid growth, clonal expansion, and invasion in BCCs. Finally, RAB27B is required for CSC-derived EV-induced stemness in BCCs. Taken together, our results indicate that RAB27B is required for maintenance of a highly tumorigenic, cancer-initiating, invasive stem-like cell population in NSCLC and RAB27B is involved in propagating EV-mediated communication from NSCLC CSCs to BCCs. Our findings further suggest that inhibition of RAB27B-dependent EV secretion may be a potential therapeutic strategy for NSCLC. Significance: Expression of RAB27B in CSCs leads to elevated levels of EVs that mediate communication between CSCs and BCCs that maintains a stem-like phenotype in NSCLC cells.

Abstract Oncologic viruses (OV) can induce tumor death through both direct oncolysis and immune-mediated destruction. Our study investigates the use of a novel OV with a Vesicular Stomatitis Virus (VSV) vector modified to express interferon-beta (IFN-b) and Tyrosinase Related Protein 1 (TYRP1) (VSV-IFNb-TYRP1). VSV is an attractive vector since humans are not naturally infected with VSV; thus, pre-existing immunity is minimal. IFN-b leads to increased T-cell responses and tumor cell apoptosis, while TYRP1, a melanocyte differentiation antigen, increases immunogenicity of the therapy. We conducted a Phase 1 clinical trial with a 3+3 design in patients with metastatic uveal melanoma. VSV-IFNb-TYRP1 was injected into a liver metastasis under image guidance, then administered on the same day as a single intravenous (IV) infusion. IV doses started at dose level (DL) 1 1 × 1010 TCID50, then escalated to DL2 3 × 10 10, DL3 1 × 1011, and DL4 3 × 1011. The dose delivered intratumorally (IT) varied based on the IV dose. The primary endpoints were safety and maximum tolerated dose (MTD). Efficacy was a secondary endpoint. Correlative studies focused on understanding viral pharmacokinetics (PK) and immunological responses induced by VSV-IFNb-TYRP1 therapy. Twelve patients with previously treated metastatic uveal melanoma were enrolled. Median follow up was 19.1 months. Four DLs were evaluated with one patient at DL4 experiencing dose limiting toxicities (DLTs), including decreased platelet count (grade 3), increased aspartate aminotransferase (AST), and cytokine release syndrome (CRS). Non-DLTs at DL4 were fatigue, fever, CRS, hematological toxicities (decreased platelets and lymphocytes), and AST elevation. Four patients had stable disease (SD) and 8 had progressive disease (PD) as their best response. ELIspot data show that three of the four patients with response to TYRP1 also had a response to gp100, suggesting possible epitope spreading. These four patients received immune checkpoint inhibitor treatment as the next line of therapy, which led to clinical benefit for two patients. Our study evaluated VSV-IFNb-TYRP1 administered via IT and IV routes in a previously treated population of metastatic uveal melanoma patients and found no major safety events. Although there were no clear objective responses to VSV-IFNb-TYRP1, dose-dependent immunogenicity to melanoma antigens was seen. While OV response alone is not sufficient for clinical benefit, the evidence of epitope spreading is encouraging. Future studies of VSV-IFNb-TYRP1 will evaluate combinations with other therapies. Citation Format: Katherine E. Smith, Adam Weisbrod, Carrie Strand, Jacob Allerd, Jose S. Pulido, Alysha Newsom, Lianwen Zhang, Nandakumar Packiriswamy, Heather Montane, Lisa Kottschade, Anastasios Dimou, Yiyi Yan, Markovic Svetomir, Kah Whye Peng, Richard G. Vile, Matthew S. Block, Roxana S. Dronca. Phase I trial of vesicular stomatitis virus expressing human interferon beta and tyrosinase related protein 1 (VSV-IFNb-TYRP1) in metastatic ocular melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT207.

Abstract Background: Radiation is a potent inducer of DNA double-strand breaks, and ribonucleotide reductase (RNR) is the rate-limiting enzyme in the synthesis and repair of DNA, making RNR-targeted therapy a rationale therapeutic strategy for radiosensitization. ETCTN 10388 (NCT04234568) evaluated safety and efficacy of the combination of lutetium 177 DOTATATE, a beta-emitting radionuclide in combination with triapine, a ribonucleotide reductase (RNR) inhibitor. Method: This study was a multicenter phase 1 dose escalation trial [using the Bayesian optimal interval design (BOIN)] of triapine in combination with fixed dose lutetium Lu 177 DOTATATE for well-differentiated somatostatin receptor-positive gastroenteropancreatic neuroendocrine tumor (GEP-NETs) after the failure of at least one line of prior systemic cancer treatment with an expansion cohort at the recommended phase 2 dose (RP2D). Oral triapine (100mg, 150mg, 200mg) was administered once daily on days 1-14 and Lu-177 DOTATATE [200 mCi] intravenously on day 1 of every 56-day cycle. A total of 4 cycles were administered. Response and adverse effects were assessed per RECIST and CTCAE 5.0, respectively. Exploratory correlative studies included tumor somatic and germline mutation testing, RNA sequencing, pharmacokinetics, deoxynucleosides and circulating cell free DNA analysis. Primary endpoints were safety and RP2D. Results: Overall, 31 patients were enrolled between 6 sites, 15 in the dose escalation phase and 16 in the dose expansion phase. Adverse events (AE) were assessed in all 31 patients per CTCAE 5.0. One DLT in dose level 1, seven DLTs in dose level 2, and one grade 5 DLT in dose level 3 were observed. The RP2D of the combination is triapine 150 mg QD (dose level 2) on days 1-14 in combination with Lu-177 DOTATATE on day 1 of every 56-day cycle. Detailed safety and adverse event data will be presented at the meeting. There were 28 patients evaluable for efficacy, of which 6 (21%) achieved a partial response. At 12 months, 6 patients had progressed, while 22 (86%) remained progression free. Median PFS has not been reached. PK data were available for 12 patients enrolled in the dose escalation cohort. The geometric mean (SD) AUC0-inf was 1159 (1.22) µg/L•h for the 100mg dose level and 1862 (1.76) µg/L•h for the 150 mg dose level, suggesting that exposure increased with dose, and inter-patient variability was as expected for an oral agent. Conclusion: The combination of triapine and Lu-177 DOTATATE was safe with preliminary efficacy signals, which will be further evaluated in ETCTN 10558, a randomized phase 2 study that is comparing the effectiveness of triapine and Lu-177 DOTATATE to Lu-177 DOTATATE alone. Citation Format: Aman Chauhan, Susanne Arnold, Jill Kolesar, William Carson, Heidi Weiss, Rani Jayswal, Donglin Yan, Riham El Khouli, Aman Khurana, Jan Beumer, Heloisa Soares, Mary Mulcahy, Thorvardur Halfdanarson, Daneng Li, Heather Jacene, Percy Ivy, Elise Kohn, John Wright, Larry Rubinstein, Zeta Chow, Piotr Rychahou, Mark B. Evers, Charles Kunos, Lowell Anthony, Bhavana Konda. ETCTN 10388: a first in human phase I trial of triapine and lutetium Lu 177 DOTATATE in well-differentiated somatostatin receptor-positive gastroenteropancreatic neuroendocrine tumors (GEP-NETs) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT194.

Pathogenic variants in KMT5B , a lysine methyltransferase, are associated with global developmental delay, macrocephaly, autism, and congenital anomalies (OMIM # 617788). Given the relatively recent discovery of this disorder, it has not been fully characterized. Deep phenotyping of the largest ( n = 43) patient cohort to date identified that hypotonia and congenital heart defects are prominent features that were previously not associated with this syndrome. Both missense variants and putative loss-of-function variants resulted in slow growth in patient-derived cell lines. KMT5B homozygous knockout mice were smaller in size than their wild-type littermates but did not have significantly smaller brains, suggesting relative macrocephaly, also noted as a prominent clinical feature. RNA sequencing of patient lymphoblasts and Kmt5b haploinsufficient mouse brains identified differentially expressed pathways associated with nervous system development and function including axon guidance signaling. Overall, we identified additional pathogenic variants and clinical features in KMT5B -related neurodevelopmental disorder and provide insights into the molecular mechanisms of the disorder using multiple model systems.

Cerebrovasculature is critical in maintaining brain homeostasis; its dysregulation often leads to vascular cognitive impairment and dementia (VCID) during aging. VCID is the second most prevalent cause of dementia in the elderly, after Alzheimer’s disease (AD), with frequent cooccurrence of VCID and AD. While multiple factors are involved in the pathogenesis of AD and VCID, APOE4 increases the risk for both diseases. A major apolipoprotein E (apoE) receptor, the low-density lipoprotein receptor-related protein 1 (LRP1), is abundantly expressed in vascular mural cells (pericytes and smooth muscle cells). Here, we investigated how deficiency of vascular mural cell LRP1 affects the cerebrovascular system and cognitive performance using vascular mural cell–specific Lrp1 -KO mice ( smLrp1 –/– ) in a human APOE3 or APOE4 background. We found that spatial memory was impaired in the 13- to 16-month-old APOE4 smLrp1 –/– mice but not in the APOE3 smLrp1 –/– mice, compared with their respective littermate control mice. These disruptions in the APOE4 smLrp1 –/– mice were accompanied with excess paravascular glial activation and reduced cerebrovascular collagen IV. In addition, blood-brain barrier (BBB) integrity was disrupted in the APOE4 smLrp1 –/– mice. Together, our results suggest that vascular mural cell LRP1 modulates cerebrovasculature integrity and function in an APOE genotype–dependent manner.

AbstractCheckpoint inhibitor (CPI) therapy with anti–PD-1 antibodies has been associated with mixed outcomes in small cohorts of patients with relapsed aggressive B-cell lymphomas after CAR-T failure. To define CPI therapy efficacy more definitively in this population, we retrospectively evaluated clinical outcomes in a large cohort of 96 patients with aggressive B-cell lymphomas receiving CPI therapy after CAR-T failure across 15 US academic centers. Most patients (53%) had diffuse large B-cell lymphoma, were treated with axicabtagene ciloleucel (53%), relapsed early (≤180 days) after CAR-T (83%), and received pembrolizumab (49%) or nivolumab (43%). CPI therapy was associated with an overall response rate of 19% and a complete response rate of 10%. Median duration of response was 221 days. Median progression-free survival (PFS) and overall survival (OS) were 54 and 159 days, respectively. Outcomes to CPI therapy were significantly improved in patients with primary mediastinal B-cell lymphoma. PFS (128 vs 51 days) and OS (387 vs 131 days) were significantly longer in patients with late (&gt;180 days) vs early (≤180 days) relapse after CAR-T. Grade ≥3 adverse events occurred in 19% of patients treated with CPI. Most patients (83%) died, commonly because of progressive disease. Only 5% had durable responses to CPI therapy. In the largest cohort of patients with aggressive B-cell lymphoma treated with CPI therapy after CAR-T relapse, our results reveal poor outcomes, particularly among those relapsing early after CAR-T. In conclusion, CPI therapy is not an effective salvage strategy for most patients after CAR-T, where alternative approaches are needed to improve post–CAR-T outcomes.