Citations

Abstract Background: Mutations in RAS is reported in embryonal rhabdomyosarcoma (ERMS). Upregulation of IGF2/IGF1R axis and IGF2 overexpression is a common finding. Targeting RAS downstream is associated with high toxicity. Combination therapies targeting parallel pathways is necessary to overcome treatment resistance. Dual inhibition of RAS downstream and IGF2/IGF1R axis can be a potential mechanism of targeted treatment. The efficacy of this mechanism was studied using a microcancer 3D exvivo tumor cell viability assay in a KRAS mutant ERMS. Design: Tumor was collected for a high-risk pediatric ERMS patient. Comprehensive genomic analysis, for identification of targetable genomic alterations, was performed by integrating WES, MPseq and RNAseq. Tumor spheroids grown in 3D environment were tested against multiple single drugs and combinations. The tumor viability was assed employing the Cell Titer Glow Luminescent Cell Viability Assay. Results were expressed as nMATP and were shown as drug-response curve exhibiting the ATP concentration changes at Cmax. Results: Genomic findings included an oncogenic KRAS (G12D) mutation. BAY-293 has a partial cell killing response as a single agent. Given to the presence of IGF2 over-expression, IGF2/IGF1R pathway was targeted by linsitinib. Addition of BAY-293 to linsitinib led to enhanced effectiveness of this agent (Table 1). Conclusion: Combination of comprehensive genomic profiling and a laboratory-based 3D micro-cancer model using the patient’s own tumor is an effective way to determine drug efficacy. Targeting RAS pathway by single agents, increases the possibility of resistance. Dual targeting of downstream pathways by MEK and PI3K pathway inhibition is highly toxic, and the clinical usage of this combination is limited. Our results have indicated inhibition of IGF-1R/IGF2 axis in combination with other agents targeting RAS pathway, can be a potential method to address these limitations. ABEL 1. Summary of molecular alterations and targeting methods Molecular alteration Drug Target Kill% at Cmax KRAS (G12D) Mutation BAY-293 RAS-SOS1 interaction 55.3 Trametinib MEK1/2 88.3 Selumetinib MEK1/2 76 Paxalisib PI3K/mTOR 89.7 Samotolisib PI3K/mTOR 92.9 Copanlisib PI3K 95.2 Perifosine AKT 89.2 IGF2 Over-expression Linsitinib IGF-1R/InsR 84.1 BMS-754807 IGF-1R/InsR 67.4 NTRK2 mutation Larotrectinib NTRK 41.9 KMT2D mutation Panobinostat HDAC 85.3 Combinations Kill% at Cmax BAY-293+Selumetinib 100 BAY-293+Samotolisib 100 BAY-293+Paxalisib 99.7 BAY-293+Linsitinib 97.5 Selumetinib+Samotolisib 93.1 Citation Format: Dorsay Sadeghian, Wan-Hsin Lin, James Smadbeck, Alan Panheiter, Michael Barrett, Alexa F. Mccune, Giannoula Karagouga, Sarah Johnson, Ryan W. Feathers, Faye R. Harris, Lindsey Kinsella, Taylor Berry, John Cheville, Panos Anastasiadis, Candace Granberg, Patricio Gargollo, Vasmatzis George. Dual inhibition of RAS and the IGF2/IGF1R pathways: a potential targeting strategy for RAS-mutated embryonal rhabdomyosarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3391.

e20005 Background: iAEs such as cytokine release syndrome (CRS) and neurotoxicity (NT) are common with CAR T cell therapies such as ide-cel; CRS and NT observed with ide-cel are generally low grade and manageable with tocilizumab (toci) and corticosteroids. Identifying iAE risk with sensitivity and specificity is challenging, suggesting multifactorial etiology and limitations evaluating dynamic processes at specific timepoints. Macrophage activation syndrome (MAS; per CTCAE) has a specific molecular profile representing a homogeneous subgroup within CRS, tending to be more severe/refractory to front-line management. Using longitudinal data on post-infusion soluble factors we aimed to develop a candidate post-infusion inflammatory risk score based on MAS molecular signature and determine associations with pt baseline characteristics. Methods: Statistical learning tools were applied to the longitudinal profile of 34 factors measured over 28 d after ide-cel infusion in 291 pts from KarMMa (NCT03361748) and KarMMa-2 (NCT03601078) to extract features describing the profiles. Unsupervised machine learning-based clustering was applied to these features and enrichment for MAS cases within each cluster was assessed. A metric describing membership in a cluster of interest was used as a candidate post-infusion inflammatory risk score for further correlative analyses. Results: Pts with MAS had cytokine profiles consistent with high levels of pro-inflammatory signalling across multiple inflammatory cell types. Cytokine profiles of MAS were qualitatively similar to those of CRS/NT; however, unsupervised clustering showed a distinct group of pts with MAS. A metric of similarity to the MAS-enriched cluster was defined as a candidate post-infusion inflammatory risk score, posited to identify pts more likely to have more severe/refractory iAEs. This inflammatory risk score positively correlated with CRS and NT grades and frequency of toci usage (Kruskal-Wallis test; all P < 0.001). A prototype predictive model based on baseline pt and clinical characteristics strongly correlated with post-infusion inflammatory risk score (Pearson; ρ = 0.88). Low blood counts, higher tumor burden, and elevated levels of inflammatory markers on the day of ide-cel infusion were associated with a higher inflammatory risk score. Conclusions: A molecular profile of severe/refractory iAEs was preliminarily identified in ide-cel treated pts with MM. This profile enabled derivation of a candidate post-infusion inflammatory risk score and a prototype predictive model of this risk score based on pt baseline characteristics was developed. These results may help identify pts at risk for severe/refractory iAEs, who may be potential candidates for closer monitoring or novel interventions, and warrant further study. Clinical trial information: NCT03361748 , NCT03601078 .

Abstract Patients with multiple myeloma (MM) who do not respond to initial therapy have worse outcomes than primary responders, and effective treatments are lacking in this population. However, the outcomes of primary refractory disease in the modern treatment era have not yet been studied. We reviewed patients with MM treated with triplet/quadruplet therapy at our institution to assess the incidence of primary refractory disease and the impact of salvage therapies in this population. We identified 1127 patients, of whom 1086 were evaluated for hematologic responses after 4 to 6 cycles. Of these, 93.3% (1013) had evidence of response, whereas 6.7% (73) had primary refractory disease. With a median overall survival (OS) of 51.3 months, patients with primary refractory disease had an increased risk of shorter survival in univariable and multivariable analyses (hazard ratio [HR], 3.5 [95% confidence interval (CI), 2.5-4.9]; HR, 4.3 [95% CI, 2.6-6.9], respectively). In the subgroup analysis of patients with primary refractory disease, those who received second-line autologous stem cell transplantation (ASCT) had increased second progression-free survival (20.9 vs 8.1 months; P &lt; .01) and second OS (74.7 vs 31.3 months; P = .02) compared with patients who did not. We conclude that early progression remains a significant factor for shorter OS in the current era, and salvage ASCT could be the most beneficial option for this population.

10514 Background: FAP is the most common hereditary adenomatous polyposis syndrome and, if left untreated, will lead to colorectal cancer development in nearly all patients. Chronic inflammation, driven in part by the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway, may promote polyp formation. Enteric-selective inhibition of the JAK/STAT pathway may provide a treatment for FAP. Lorpucitinib is an oral, small molecule, potent pan-JAK inhibitor with favorable enteric-selective properties. Here, we report the efficacy, safety, and pharmacokinetic (PK) results from a phase 1b study of lorpucitinib in patients with FAP (NCT05014360). Methods: Patients aged ≥18 years with ≥6 polyps ≥2 mm in diameter in the rectum or colon with FAP ( APC germline mutation or obligate carrier) received lorpucitinib 75 mg twice daily for 24 weeks. The primary objective was to evaluate the effect of lorpucitinib on colorectal polyp burden at Week 24, assessed by endoscopy at baseline and Week 24. Secondary objectives were safety, PK, and biomarker assessments of lorpucitinib activity. Results: Overall, 42 (23 pre-colectomy; 19 post-colectomy) patients with FAP were enrolled, with a median age of 33 (range, 19-61) years. No clear effect on polyp burden was observed at Week 24. Gut mucosal and polyp concentrations of lorpucitinib were much higher than plasma concentrations, indicating an enteric-selective distribution. Mean sigmoid colon, rectum, and polyp concentrations of lorpucitinib at Week 8 were 112-, 473-, and 108-fold higher, respectively, than the observed maximum plasma concentration at Week 8 (1 hour). At Week 8, lorpucitinib achieved JAK tyrosine kinase inhibition in mucosal biopsies as evidenced by a median 37% reduction in normalized pSTAT-3 levels. Lorpucitinib reduced serum-based inflammatory biomarkers such as C-reactive protein and serum amyloid A by Week 16 of therapy. Some patients reported an improvement of clinical symptoms such as less frequent bowel movements and less blood in the stool. The most common adverse events (AEs) were abdominal pain (16%), bilirubin increased (13%), headache (13%), lipase increased (13%), and diarrhea (13%). There were no treatment-related serious AEs, grade 3 treatment-emergent AEs, serious infections, or venous thromboembolisms. Conclusions: These results show that lorpucitinib had no clear effect on polyp burden. The study found that lorpucitinib is safe and exhibits an enteric-selective distribution in FAP patients. Inhibition of JAK tyrosine kinase signaling was associated with reduced STAT-3 phosphorylation in mucosal biopsies from FAP patients. While reductions observed in polyp burden were not clinically significant, lorpucitinib treatment lowered levels of several serum inflammatory biomarkers. Treatment with lorpucitinib was safe and well tolerated, and may improve clinical symptoms associated with FAP. Clinical trial information: NCT05014360 .

9065 Background: Rearranged during transfection ( RET) gene alterations are the oncogenic driver in diverse tumor types, including RET fusions identified in 1-2% of non-small cell lung cancers (NSCLC). While RET-selective tyrosine kinase inhibitors (TKIs) selpercatinib and pralsetinib are effective, acquired drug resistance remains a challenge. Here, we report the initial results from the RETgistry, an international consortium aimed at elucidating mechanisms of resistance to RET TKIs across RET-altered solid tumors. Methods: This was a retrospective analysis performed across 16 institutions. Patients (pts) were eligible if they had advanced solid tumor harboring an oncogenic RET alteration, received ≥1 RET TKI with disease progression, and underwent resistant tumor or liquid biopsy for next-generation sequencing (NGS). Results: A total of 103 time-distinct biopsies (62 tissue, 30 plasma, 11 paired tissue/plasma) were included in analysis, obtained from 88 pts with progression on a RET-selective TKI [selpercatinib (n = 70), pralsetinib (n = 14), selpercatinib and pralsetinib sequentially (n = 4)]. Pts had the following tumor types: 72 NSCLC (69% KIF5B-RET, 21% CCDC6-RET, 10% other RET fusion), 13 medullary thyroid cancer (TC) (54% RET M918T, 46% other RET mutation), and 2 papillary and 1 anaplastic TC (all, RET fusion). Median age was 58 (range, 21-86); 48% were male with 89% never/light smokers. Median duration of RET TKI preceding biopsies [first-line, n = 32 (31%); second-line, n = 42 (41%); third-/greater-line, n = 29 (28%)] was 16.5 months (mos) (95% CI, 14.0-19.6); median PFS was 14.1 mos (95% CI, 9.3-17.0). Resistant biopsies were obtained at median 15.0 mos from TKI initiation (range, 1.8-58.8). Acquired RET mutations were detected in 14 (14%), most common being G810 substitutions in 12 (12%). Potential off-target resistance gene alterations identified in 43 cases (42%) included MET amplification (14%), BRAF V600E or fusion (2%), KRAS gain or mutation (5%), ERBB2 amplification (2%), EGFR amplification (3%), ROS1 fusion (1%), and activating PIK3CA mutation or PTEN loss (4%). No resistant lung cancer biopsy demonstrated small cell transformation. The duration of TKI therapy (HR 0.64, p = 0.11) or PFS (HR 0.75, p = 0.33) did not differ according to the presence of on-target vs off-target resistance. NGS analyses of pre-RET-selective TKI tumors (n = 92) revealed frequent co-occurring alterations in TP53 (29%) and CDKN2A/B (12%). Conclusions: On-target resistance to RET inhibition due to acquired RET mutations was less common than off-target resistance, identified in 14%. The majority of RET TKI resistance is mediated by off-target mechanisms such as bypass receptor tyrosine kinase activation. Further studies are warranted to enable the development of therapeutic strategies to address resistance in pts with RET-altered tumors. The RETgistry accrual and data analyses continue.

9037 Background: The clinical outcomes for patients with NSCLC remain suboptimal despite recent advancements in anti-PD-1/PD-L1 immunotherapies. Thus, identification of rational combinations of novel immune checkpoint (IC) strategies is imperative. This study aimed to comprehensively characterize the expression of IC targets to inform drug development and design effective combinatorial strategies, to advance the search for optimized therapies for NSCLC. Methods: We analyzed the differential gene expression of IC targets in 537 primary lung adenocarcinoma (LUAD) samples and 59 normal lung tissue samples pre-immunotherapy receipt using RNA-sequencing data from The Cancer Genome Atlas. Gene expression of IC-targets including PDCD1 (PD-1), CD274 (PD-L1), CTLA4, TIGIT, LAG3, HAVCR2 (TIM-3), VSIR (VISTA), ICOS, CD276 (B7-H3), BTLA, IDO1, KLRD1 (CD94/NKG2A), NT5E (CD73), TNFRSF4 (OX-40), TNFRSF18 (GITR), and TNFRSF9 (4-1BB) were obtained. Differential gene expression was determined intra-tumorally by comparison of transcripts per million and inter-tumorally using the DESeq2 algorithm. Log2 fold change >0.5 and false discovery rate adjusted P<0.05 were used as criteria for significant differential expression. Hierarchical clustering was used to identify subsets of tumors with similar profiles of IC-targetable gene expression. Results: Tumors showed significantly increased expression of TNFRSF18 (GITR), NT5E (CD73), TNFRSF9 (4-1BB), LAG3, TIGIT, CTLA4, PD-1, BTLA, B7-H3, and OX-40 (Table 1). On the other hand, tumors exhibited significant downregulation of CD274 (PD-L1), HAVCR2 (TIM-3), ICOS, KLRD1 (CD94/NKG2A), and VSIR (VISTA). Hierarchical clustering revealed recurrent patterns of IC gene overexpression which were characterized by: 1) IDO1-hi, 2) CD276-mid + TNFRSF18-mid, 3) VSIR-hi, 4) CD276-hi, 5) NT5E-hi, and 6) CD276-mid + NT5E-mid. Interestingly, patterns of IC gene expression distinguish tumors from controls. Of note, high VSIR expression was specific to normal tissue rather than tumors. Conclusions: Our study identified many IC targetable genes that were significantly overexpressed in tumors. However, subsets of tumors showed distinct and segregable combinations of overexpressed IC genes. These results suggest heterogeneous mechanisms of immune evasion in NSCLC, which may explain suboptimal outcomes with anti-PD-1/PD-L1 based strategies in this patient population. Our findings emphasize the importance of biomarker-guided approaches for the optimal selection of ICs and the development of rational combinatorial immunotherapies in NSCLC.

9029 Background: Molecular biomarkers such as EML4-ALK fusion variant 3 (V3) and TP53 mutation are associated with poor prognosis in patients (pts) with anaplastic lymphoma kinase fusion positive ( ALK+) non–small cell lung cancer (NSCLC). We evaluated the effect of EML4-ALK fusion variants and TP53 mutation status on time to treatment discontinuation (TTD) of first-line (1L) treatment with a next-generation ALK tyrosine kinase inhibitor (TKI) in pts with ALK+ NSCLC in the real-world setting. Methods: Pts with advanced/metastatic NSCLC who were ALK+ in circulating tumor DNA by Guardant360 (G360) liquid biopsy test from Jan 1, 2018, to Dec 31, 2021, and received 1L monotherapy with a next-generation ALK TKI (alectinib, brigatinib, ceritinib, lorlatinib) were identified in the Guardant INFORM clinical-genomics database. Median TTD of 1L ALK TKI treatment was determined by Kaplan-Meier (KM) methods. The impact of EML4-ALK fusion variant and TP53 mutation status on TTD was evaluated. Results: Database search identified 495 pts with advanced/metastatic NSCLC who had ALK fusion by G360; of these, 214 pts received 1L treatment with a next-generation ALK TKI; 164 had G360 testing before treatment (alectinib, n=147; brigatinib, n=7; ceritinib, n=2; lorlatinib, n=8). Among these 164 pts, median age was 58.6 y, 53% were female, and 29% had baseline brain metastases. Median follow-up from start of 1L treatment was 14.8 mo. Median TTD was 19.6 mo (95% CI: 13.6–not reached [NR]). TP53 mutations were detected in 66 pts (40%). Median (95% CI) TTD in pts with TP53 mutation vs WT was 17.1 (9.5–28.5) vs 21.9 mo (14.3–NR; log-rank P=0.1712). Of 130 pts with EML4-ALK fusion variant type detected, 63 (48%) had V1, 54 (42%) V3, 8 (6%) V2, 4 (3%) V5, and 1 (1%) V8. In pts with EML4-ALK fusion V1 vs V3, median (95% CI) TTD was 19.0 (13.6–NR) vs 21.8 mo (8.7–NR; HR: 0.73; log-rank P=0.3039), with the KM plot showing numerically longer TTD in pts with V1 vs V3 during the first 18 mo and lines crossing at the tail end. Of 117 pts with both an EML4-ALK fusion variant (V1/V3) and TP53 data, 21 (18%) had both V3 and a TP53 mutation. Pts with co-occurring EML4-ALK V3 and TP53 mutation had the shortest TTD (median TTD 8.7 [3.9–NR; HR: 2.59; P=0.0219]; Table). Conclusions: Among pts with NSCLC and ALK fusion, co-occurrence of EML4-ALK V3 and TP53 mutation is common and associated with poor prognosis and high risk of early discontinuation of 1L treatment with a next-generation ALK TKI, most likely due to disease progression. Additional novel or combination therapies are warranted for this subpopulation. [Table: see text]

9004 Background: Despite advances in first-line (1L) immunotherapy ± CT, most patients (pts) with aNSCLC experience disease progression, necessitating novel strategies. Dato-DXd is an antibody drug conjugate (ADC) composed of a humanized anti-TROP2 IgG1 monoclonal antibody covalently linked to a topoisomerase I inhibitor payload via a plasma-stable tetrapeptide-based cleavable linker. Dato-DXd had encouraging efficacy and manageable safety in heavily pretreated aNSCLC. Dato-DXd + immunotherapy yielded greater preclinical activity than either agent alone. Methods: TROPION-Lung02 (NCT04526691) is a phase 1b, global, dose-escalation and -expansion study evaluating Dato-DXd (4 or 6 mg/kg) + pembro 200 mg ± Pt-CT (cisplatin 75 mg/m2 or carboplatin AUC 5) every 21 days across 6 cohorts. Pts in escalation may have received ≤2 prior lines of therapy for aNSCLC. Pts in expansion were primarily treatment (tx) naive (pts receiving Dato-DXd + pembro may have ≤1 prior Pt-based tx). The primary objective is to assess safety and tolerability, including dose-limiting toxicities (DLTs). Secondary objectives include evaluation of efficacy, pharmacokinetics, and immunogenicity. Results: As of the Oct 31, 2022, data cutoff (DCO), 120 pts were treated. All cohorts met DLT criteria to move to escalation. Median age was 65 years. PD-L1 expression was <1%, 1%-49%, and ≥50% in 40%, 33%, and 26% of pts, respectively. Median tx duration was 4.6 mo, with 55% receiving tx at DCO. The most frequent any-grade (gr) tx-emergent adverse events (TEAEs) were nausea (45%) and stomatitis (45%). Gr ≥3 TEAEs occurred in 61% of pts; most frequent were neutrophil count decreased (8%) and amylase increased (8%). TEAEs that were serious, associated with discontinuation, or associated with death occurred in 31%, 24% (16% associated with Dato-DXd), and 6% of pts, respectively. Dose reductions due to TEAEs associated with Dato-DXd occurred in 17%. Drug-related interstitial lung disease occurred in 12 pts (10%; 9 gr 1/2; 3 gr 3). The objective response rate (ORR) with 1L Dato-DXd + pembro doublet and Dato-DXd + pembro + Pt-CT triplet tx was 60% (95% CI, 36%-81%; 12 [2 unconfirmed]/20) and 55% (95% CI, 39%-70%; 23 [5 unconfirmed]/42), respectively. The ORR for any line of therapy was 38% (95% CI, 25%-54%; 18 [2 unconfirmed]/47) with doublet and 47% (95% CI, 34%-60%; 28 [5 unconfirmed]/60) with triplet tx. In both subsets, the disease control rate was 85% and median duration of response was not reached. Responses were observed in all 3 PD-L1 expression level subgroups. Although immature, median progression-free survival (95% CI) was 10.8 (8.3-15.2) and 7.8 mo (5.5-NE) with doublet and triplet tx, respectively. Conclusions: Dato-DXd + pembro ± Pt-CT demonstrated tolerable safety with notable 1L activity in this first and largest dataset with an ADC + immunotherapy ± Pt-CT in aNSCLC pts. Clinical trial information: NCT04526691 .