ROS1 Tyrosine Kinase Inhibitors Research Articles

Abstract LB182: Mutagenesis screens support potential best-in-class profile for selective, brain-penetrant, and TRK-sparing ROS1 inhibitor NVL-520

Abstract Introduction. ROS1 fusions are recurrent oncogenic drivers in non-small cell lung cancer (NSCLC). Tyrosine kinase inhibitors (TKIs) crizotinib, entrectinib, and repotrectinib have been approved for the treatment of ROS1-positive NSCLC. Response to these TKIs can be limited by emergence of drug resistance, with ~40% of patients acquiring on-target ROS1 mutations at progression on crizotinib. NVL-520 is an investigational, brain-penetrant, and TRK-sparing ROS1 TKI designed to maintain activity for ROS1 mutations that confer resistance to approved therapies. To investigate suppression of resistance by NVL-520, we performed two N-ethyl-N-nitrosourea (ENU) mutagenesis screens and determined the frequency and identity of resistance mutations following treatment with NVL-520 versus earlier-generation ROS1 TKIs. Methods. Cells were treated with ENU for 1 day followed by crizotinib, entrectinib, repotrectinib, or NVL-520 for 28 days. Frequency of resistance indicates the fraction of wells that proliferated on day 28 despite continuous TKI treatment. Resistance mutations in the ROS1 kinase domain were identified by Sanger sequencing. Resistant clones harboring ROS1 kinase-domain mutations were expanded and used to profile the inhibitory activity of ROS1 TKIs. Results. The first ENU screen was performed on Ba/F3 CD74-ROS1, simulating a first-line treatment setting. NVL-520 at an unbound drug concentration (Cunbound) of 8.2 nM yielded 1 resistant clone among 480 replicate wells (frequency of resistance = 0.2%). The second screen was performed on Ba/F3 CD74-ROS1 G2032R, which is the most common point mutation after progression on previous-generation therapies, simulating a later-line treatment setting. NVL-520 at Cunbound of 41 nM yielded 6 resistant clones among 480 replicate wells (frequency of resistance = 1.3%). These NVL-520 concentrations (8.2 - 41 nM) were well within its average Cunbound of 166 nM at the recommended phase 2 dose (RP2D) of 100 mg once daily. None of the 7 resistant clones harbored ROS1 kinase-domain mutations, suggesting an off-target resistance mechanism. Crizotinib, entrectinib, and repotrectinib at their respective average human Cunbound yielded frequencies of resistance ranging from >33% to 100% in at least one of the screens, indicating that they were less effective than NVL-520 at suppressing resistance in these screens. Conclusion. NVL-520 was highly effective at suppressing resistance in ENU mutagenesis screens simulating first-line (CD74-ROS1) and later-line (CD74-ROS1 G2032R) treatment. The screens did not reveal any novel ROS1 mutations that could confer resistance to NVL-520 at the RP2D. The broad preclinical activity against ROS1 and diverse ROS1 mutations, together with its brain penetrance and TRK-sparing design, suggests NVL-520 as a potential best-in-class ROS1 therapy. Citation Format: Anupong Tangpeerachaikul, Franklin Gu, Henry E. Pelish. Mutagenesis screens support potential best-in-class profile for selective, brain-penetrant, and TRK-sparing ROS1 inhibitor NVL-520 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB182.

ROS1 Positive Non-Small Cell Lung Cancer Patient with Brain Metastases Who Overcame Crizotinib Resistance with Lorlatinib: Case Report

Background: ROS1-positive patients account for 1-2% of non small cell lung cancer (NSCLC) cases. Crizotinib is the first tyrosine kinase inhibitor (TKI) indicated in first line treatment of ROS1-rearranged NSCLC. However, crizotinib resistance is frequent within the first 12 months of treatment. Lorlatinib is a novel tyrosine kinase inhibitor of ROS-1 recently indicated for metastatic or locally advanced crizotinib-resistant NSCLC. Case report: We report a case of a 43-year-old female patient with no medical history, diagnosted with stage IVB NSCLC including asymptomatic brain metastasis, and harboring ROS1 rearrangement. Within the first three months of starting crizotinib, the patient showed on CT scan evaluation new bone and brain metastases. Lorlatinib in the second line revealed a noteworthy improvement in metastasis and primary lesion. Conclusion: Brain metastases frequently occur in ROS1-rearranged NSCLC at the time of diagnosis and treatment course. However the efficacy of crizotinib might not translate to intracranial control of the disease, one of the cause of resistance to this drug.

Clinical outcomes of ROS1-positive non-small cell lung cancer with limited access to ROS1-tyrosine kinase inhibitors (TKIs): experience from an Indian tertiary referral centre.

ROS1 as a driver mutation is observed in approximately 1%-2% of all non-small cell lung cancer (NSCLC). Given its rarity, we share our experience regarding ROS1-positive NSCLC including the access to ROS1 tyrosine kinase inhibitors (TKIs) in a low-middle income country like India. It is a retrospective analysis of ROS1-positive NSCLC patients registered between January 2015 to December 2021 for demographics, treatment patterns and outcomes i.e., overall survival (OS) and progression free survival (PFS). Baseline characteristics were available for 70 patients of 78 patients positive for ROS1 by fluorescent in situ hybridisation. Median age at presentation was 52 years, 39 (55.7%) were males, most (51, 72.86%) were non-smokers and ten patients (14.3%) had poor Eastern Cooperative Oncology Group (ECOG) performance status (PS) i.e., PS >2 at presentation. A total of 67 patients receiving cancer directed therapy were analysed for survival. The first line (1L) therapies included - ROS1 TKIs in 38, chemotherapy in 20, epidermal growth factor receptor TKI in eight and chemotherapy-bevacizumab in one only. ROS1 TKI was provided to 20 patients as part of an assistance programme. The median OS for patients who received ROS1 TKI was not attained (95% CI 37.85-NA), while it was 8.11 (95% CI 6.31-NA) months for those who did not (HR-0.1673). The median PFS for the 1L ROS1 TKI compared to the no-TKI group was 27.07 (95% CI 24.28-NA) months versus 5.78 (95% CI 3.42-12) months (HR: 0.2047). Poor ECOG PS at presentation was the only independent prognosticator for survival. Using ROS1 TKI improves clinical outcomes in all-comers though statistically not significant. To further improve outcomes, future trials should pay special attention to patients with poor PS and find a way to increase the current limited access to TKI.

Repotrectinib in ROS1 Fusion–Positive Non–Small-Cell Lung Cancer

BackgroundThe early-generation ROS1 tyrosine kinase inhibitors (TKIs) that are approved for the treatment of ROS1 fusion–positive non–small-cell lung cancer (NSCLC) have antitumor activity, but resistance develops in tumors, and intracranial activity is suboptimal. Repotrectinib is a next-generation ROS1 TKI with preclinical activity against ROS1 fusion–positive cancers, including those with resistance mutations such as ROS1 G2032R.MethodsIn this registrational phase 1–2 trial, we assessed the efficacy and safety of repotrectinib in patients with advanced solid tumors, including ROS1 fusion–positive NSCLC. The primary efficacy end point in the phase 2 trial was confirmed objective response; efficacy analyses included patients from phase 1 and phase 2. Duration of response, progression-free survival, and safety were secondary end points in phase 2.ResultsOn the basis of results from the phase 1 trial, the recommended phase 2 dose of repotrectinib was 160 mg daily for 14 days, followed by 160 mg twice daily. Response occurred in 56 of the 71 patients (79%; 95% confidence interval [CI], 68 to 88) with ROS1 fusion–positive NSCLC who had not previously received a ROS1 TKI; the median duration of response was 34.1 months (95% CI, 25.6 to could not be estimated), and median progression-free survival was 35.7 months (95% CI, 27.4 to could not be estimated). Response occurred in 21 of the 56 patients (38%; 95% CI, 25 to 52) with ROS1 fusion–positive NSCLC who had previously received one ROS1 TKI and had never received chemotherapy; the median duration of response was 14.8 months (95% CI, 7.6 to could not be estimated), and median progression-free survival was 9.0 months (95% CI, 6.8 to 19.6). Ten of the 17 patients (59%; 95% CI, 33 to 82) with the ROS1 G2032R mutation had a response. A total of 426 patients received the phase 2 dose; the most common treatment-related adverse events were dizziness (in 58% of the patients), dysgeusia (in 50%), and paresthesia (in 30%), and 3% discontinued repotrectinib owing to treatment-related adverse events.ConclusionsRepotrectinib had durable clinical activity in patients with ROS1 fusion–positive NSCLC, regardless of whether they had previously received a ROS1 TKI. Adverse events were mainly of low grade and compatible with long-term administration. (Funded by Turning Point Therapeutics, a wholly owned subsidiary of Bristol Myers Squibb; TRIDENT-1 ClinicalTrials.gov number, NCT03093116.)

Clinical Perspectives on the Evolution of Non-small Cell Lung Cancer Treatment With Immuno-oncology and ROS1 Tyrosine Kinase Inhibitors

The non-small cell lung cancer (NSCLC) treatment landscape has rapidly evolved over the last two decades. The addition of immuno-oncology (I-O) and targeted agents has improved treatment options for patients with non-metastatic and metastatic NSCLC; however, there remains significant unmet need. In this symposium, Jürgen Wolf, University Hospital Cologne, Germany; Tina Cascone, MD Anderson Cancer Center, Houston, Texas, USA; and Jose Luis Campo-Cañaveral de la Cruz, Puerta de Hierro Majadahonda University Hospital, Madrid, Spain, discussed the increasingly complex NSCLC treatment landscape, and how the latest data may impact treatment selection. This symposium focused on I-O monotherapy and I-O combinations in treatment-naïve metastatic NSCLC, as well as the application of I-O in non-metastatic or resectable NSCLC in the neoadjuvant, peri-operative, and adjuvant settings. In addition, the latest data regarding treatment options for patients with targetable alterations, such as ROS1, were discussed, with a focus on next generation tyrosine kinase inhibitors (TKI), and how these may impact treatment selection in the future. The role of the surgeon as part of the multidisciplinary team was also discussed, with particular attention to assessment and definition of surgical complexity, as well as the importance of close collaboration and communication between the multidisciplinary team (MDT) and the patient, to ensure they are receiving the optimal treatment at the right time to improve outcomes.

Abstract C148: Type II ROS1 inhibitors and their liability on ROS1 rearranged non-small cell lung cancer with L2086F mutation

Abstract Introduction: Fusion oncoproteins involving the ROS1 receptor tyrosine kinase have been established as validated therapeutic targets in non-small cell lung cancer. FDA-approved ROS1 tyrosine kinase inhibitors (TKIs) such as crizotinib and entrectinib have shown substantial response rates in these patients, leading to improved outcomes. Historically, the solvent-front ROS1 kinase mutation, G2032R, was a recurrent resistance liability to first generation ROS1 TKI. Next-generation TKIs, including NVL-520, repotrectinib, and taletrectinib are active against the ROS1 G2032R and shown activity in both treatment-naïve and ROS1 G2032R acquired resistance setting. We and others showed that ROS1 L2086F a mutation in catalytic-spine 6 within the kinase domain confers resistance to all first and next-generation type I binding mode TKIs. Cabozantinib, a type II ROS1 inhibitor, is the only FDA-approved TKI that has showed clinical activity against ROS1 L2086F. Recent reports indicated that gilteritinib, an FLT3 TKI, exhibits activity against ALK L1256 (homologous to ROS1 L2086F). In this study, we investigated the efficacy of gilteritinib compared to cabozantinib in ROS1 L2086F resistance model systems. Methods: We tested the effectiveness of ROS1 TKI compared to gilteritinib in Ba/F3 cell lines expressing CD74-ROS1 and EZR-ROS1 resistant mutations. Additionally, we quantified the efficacy of cabozantinib and gilteritinib in ROS1 L2086F using soft agar assays. We engineered CRISPR-Cas9 genome-edited CUTO-28 cells expressing endogenous L2086F mutation, and to validate the activity of gilteritinib and cabozantinib against ROS1 L2086F. Results: The ROS1 kinase mutations F2004C, G2032R and L2086F are resistant to entrectinib inhibition. Cabozantinib, consistent with our previous published data, retains inhibitory activity against ROS1 G2032R and ROS1 L2086F, however the ROS1 F2004C mutation imposes cabozantinib-resistance. Gilteritinib, intriguingly, is active with IC50 ≤ 25 nM against ROS1 F2004C and ROS1 L2086F but not ROS1 G2032R. Immunoblotting studies showed on-target inhibition of ROS1 auto-phosphorylation and effector ERK1/2 activation in the case of ROS1 L2086F mutant cells treated with cabozantinib and gilteritinib. Conclusion: Gilteritinib demonstrates inhibitory activity against ROS1 L2086F mutation. Currently, patients with ROS1 L2086F resistance can be treated with cabozantinib as a second-line treatment option. The preclinical data presented herein suggest that gilteritinib could be an additional, potentially viable alternative to target the highly resistant ROS1 L2086F mutation. Additional studies are needed to explore the use of gilteritinib for ROS1 rearranged NSCLC. Citation Format: Rajat Thawani, Clare Keddy, Matteo Repetto, Kristen Jones, Katelyn Nicholson, Zoe Beach, Alexander Drilon, Monika Davare. Type II ROS1 inhibitors and their liability on ROS1 rearranged non-small cell lung cancer with L2086F mutation [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C148.

Abstract PR003: Repotrectinib in patients with ROS1 fusion-positive (ROS1+) non-small cell lung cancer (NSCLC): Update from the pivotal phase 1/2 TRIDENT-1 trial

Abstract Introduction: Repotrectinib, a next-generation ROS1 tyrosine kinase inhibitor (TKI), has demonstrated durable activity and manageable safety in patients (pts) with locally advanced/metastatic ROS1+ NSCLC in the pivotal phase 1/2 TRIDENT-1 trial (NCT03093116). We report efficacy with a minimum follow-up of 14 months (mo) from start of treatment in two ROS1+ NSCLC primary efficacy cohorts and safety in all pts treated at the recommended phase 2 dose (RP2D). Methods: Pts with ROS1+ NSCLC were assigned to 4 cohorts by treatment history: TKI-naïve, 1 TKI and no chemo, 1 TKI and 1 platinum-based chemo, and 2 TKIs and no chemo. Repotrectinib RP2D was 160 mg once daily for 14 days, then 160 mg twice daily. Phase 2 primary endpoint was confirmed objective response rate (cORR) by Blinded Independent Central Review per RECIST v1.1. Secondary endpoints included duration of response (DOR), progression-free survival (PFS), intracranial ORR, cORR in TKI-pretreated pts with ROS1 G2032R NSCLC, and safety. Efficacy analyses included pts with ≥14 mo follow-up. Safety assessments included pts treated at RP2D across all study cohorts. Results: At data cutoff (December 19, 2022), median (range) follow-up in the primary efficacy cohorts was 24.0 (14.2–66.6) mo in the TKI-naïve cohort (n=71) and 21.5 (14.2–58.6) mo in the 1 prior TKI and no chemo cohort (n=56). In the TKI-naïve cohort, cORR was 79% (95% CI, 68–88). Median (95% CI) DOR was 34.1 (25.6–not estimable [NE]) mo; estimated 12- and 18-mo DOR rates were 83% (73–93) and 79% (68–90), respectively. Median PFS (95% CI) was 35.7 (27.4–NE) mo; estimated 12- and 18-mo PFS rates were 77% (66–87) and 70% (59–81), respectively. In the 1 prior TKI and no chemo cohort, cORR was 38% (95% CI, 25–52). Median DOR (95% CI) was 14.8 (7.6–NE) mo; estimated 12-mo DOR rate was 56% (34–77). Median PFS (95% CI) was 9.0 (6.8–19.6) mo; estimated 12-mo PFS rate was 41% (27–56). The median (range) time to response was 1.8 (0.9–5.6) mo in the TKI-naïve cohort and 1.8 (1.6–3.6) mo in the 1 prior TKI and no chemo cohort. Among pts with measurable brain metastasis at baseline, intracranial ORR was 89% (95% CI, 52–100) in the TKI-naïve cohort (n=9), and 38% (95% CI, 14–68) in the 1 prior TKI and no chemo cohort (n=13). In pts with TKI-pretreated ROS1 G2032R NSCLC (n=17), cORR was 59% (33–82). Among pts receiving repotrectinib at RP2D (n=426), treatment-emergent adverse events (TEAEs) occurred in 422 (99%), most commonly dizziness (62%). Grade ≥3 TEAEs occurred in 216 (51%) and were considered treatment-related in 122 (29%). TEAEs led to dose reduction and treatment discontinuation in 38% and 7% of pts, respectively. Additional analysis in CNS efficacy and by subsequent therapies will be presented. Conclusion: With a minimum follow-up of 14 mo in TRIDENT-1, repotrectinib continued to demonstrate durable efficacy in pts with ROS1+ NSCLC, including intracranial activity, in both TKI-naïve and 1 prior TKI and no chemo cohorts. Safety in pts treated at RP2D was manageable, consistent with previous reports in all treated pts. Prior:WCLC(Sep 10). Citation Format: Jessica J Lin, Byoung Chul Cho, D. Ross Camidge, Sang-We Kim, Benjamin Solomon, Rafal Dziadziuszko, Benjamin Besse, Koichi Goto, Adrianus Johannes de Langen, Jürgen Wolf, Ki Hyeong Lee, Sanjay Popat, Christoph Springfeld, Misako Nagasaka, Enriqueta Felip, Nong Yang, Shun Lu, Steven Kao, Vamsidhar Velcheti, Parneet Cheema, Shanna Stopatschinskaja, Minal Mehta, Denise Trone, Felipe Ades, Christophe Y. Calvet, Alexander Drilon. Repotrectinib in patients with ROS1 fusion-positive (ROS1+) non-small cell lung cancer (NSCLC): Update from the pivotal phase 1/2 TRIDENT-1 trial [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr PR003.

Preliminary Results of Phase 2 Open Label Study of Lorlatinib Monotherapy in Relapsed/Refractory ALK + Lymphomas Previously Treated with Other Tyrosine Kinase Inhibitors

Introduction: Both aggressive T and B cell lymphoma may harbour Anaplastic Lymphoma Kinase (ALK) translocations: ALK+ Anaplastic Large Cell lymphoma (ALCL) offer a good outcome with first line therapy with 5-year survival of 79%, but relapses occur in half of the patients (pts) and salvage therapy still represents a challenge for clinicians; ALK+ large B cell lymphoma (LBCL) are very rare cases but with dismal prognosis. In addition other hematologic neoplasms can be caused by ALK fusions. Crizotinib, an ALK/MET tyrosine kinase inhibitor (TKI), provides long-term response in up to 70% relapsed/refractory (R/R) ALK+ ALCL and can obtain a similar but less durable response rates in ALK+ LBCL. In both cases the loss of response to crizotinib is frequently a fatal event. Lorlatinib, a selective ALK and ROS1 TKI, demonstrated preclinical inhibition of all reported ALK kinase domain mutations responsible for resistance to Crizotinib. Methods: From 2019 to 2022 six relapsed/refractory ALK + neoplasm pts previously treated with at least one ALK-inhibitor were enrolled in a phase 2 open label monocentric study with lorlatinib monotherapy (EudraCT2016-003970-41): Three patients had diagnosis of ALK+ LBCL (# 1, 2, 3) and 2 (#5 and #6) had ALK+ ALCL. One patient (#4) with an ALK+ histiocytosis was also included. Median age was 22 years (range 19-57), Ratio M/F was 1, all pts were in stage IV. Median prior therapy lines was 3 (range 2-5); all pts previously received Crizotinib, two pts received also Alectinib and 1 Ceritinib as TKI treatment. Lorlatinib was administered daily at dose of 100 mg. Clinical, laboratory, radiological and molecular data were collected at screening and during scheduled follow-up. Response was evaluated with 18F-FDG PET/CT (and with contrast enhanced (ce) CT scan) according Lugano Classification, and with ALK RT-PCR on peripheral blood and bone marrow. Side effects were classified according to CTCAEv4.03. PFS and OS were determined from Lorlatinib start to relapse and/or death. The primary endpoint was the evaluation of ORR considering 18F-FDG PET/CT scan and ALK- RT-PCR. Secondary endpoints were: PFS, OS, toxicity, QoL. Results: ALK rearrangement fusion pattern was detected in 6/6 pts: 3 pts with LBCL harboured Clathrin-ALK (CTCL::ALK) rearrangement and 2 ALCL pts the ATIC::ALK fusion; the ALK+ histiocytosis patient harbored an EML4::ALK rearrangement. Median follow-up was 13.7 months (IQR 22-55). At month +1 (M1) 3/6 patients had complete response (CR) defined as complete metabolic and complete radiologic response (CMR/CR) according to PET/CT scans and ALK RT-PCR negativity. The remaining 3 pts had a partial response (PR), for an Overall Response Rate (ORR) of 100% (95%CI: 0.6-1.0). One pt is still on treatment and in CR at 45 months, receiving Lorlatinib 100 mg daily with neither toxicities nor need for Allogenic Stem Cell Transplantation (ASCT); 2 CR pts underwent ASCT after 1 month, resumed lorlatinib after ASCT and are still in CR. 2 pts with PR relapsed within month +3: one pt received salvage therapy without benefit, the other one underwent ASCT but progressed 3 months later. Both pts had ALK+ BCL with CTCL-ALK rearrangement. 1 pts in PR AT M1 (ALK+ istiocytosis) obtain CR at M3 after surgical resection of a residual lung mass and is still receiving Lorlatinib at month 36. Median PFS and OS were not reached: PFS at 6 and 12 months is 83% and 62% respectively; OS at 6 and 12 months is 83% and 55%. Safety: 2/6 pts had thrombocytopenia grade 1, whereas 3/6 pts showed grade I-II hypertriglyceridemia/hypercholesterolemia and muscle cramps. Conclusions: Lorlatinib represents a safe and effective salvage therapy for ALK+ Lymphoma patients failing first line TKI treatment. The obtainment of CR at M1 seems to represent a pivotal prognostic factor. Lorlatinib also offers a promising bridging regimen to salvage ASCT especially for ALK+ BCL patients, with high response rates and no additional toxicities, .

Repotrectinib's Clinical Benefit and Its Brain Penetration in a Patient with Meningeal Carcinomatosis from G2032R-Mutated ROS-1 Positive Non-Small Cell Lung Cancer.

In this work, we report on a clinically significant response of meningeal carcinomatosis to repotrectinib in a woman with a heavily pretreated ROS1-rearranged non-small cell lung cancer (NSCLC) that harbored the concomitant solvent front G2032R mutation. Meningeal carcinomatosis has a higher incidence in oncogene addicted NSCLC due to increased life expectancy, yet no report has ever documented the activity of repotrectinib in this context. In line with its activity, we documented the presence of the drug at potentially active concentrations in the cerebrospinal fluid. Nevertheless, the short-lived response reported by our patient highlights the importance for novel ROS1-tyrosine kinase inhibitors (TKIs) to be specifically developed to be able to penetrate the blood-brain barrier.

Pan-tumor survey of ROS1 fusions detected by next-generation RNA and whole transcriptome sequencing

BackgroundTwo ROS1 tyrosine kinase inhibitors have been approved for ROS1 fusion positive (ROS1+) non-small cell lung cancer (NSCLC) tumors. We performed a pan-tumor analysis of the incidence of ROS1 fusions to assess if more ROS1+ patients who could benefit from ROS1 TKIs could be identified.MethodsA retrospective analysis of ROS1 positive solid malignancies identified by targeted RNA sequencing and whole transcriptome sequencing of clinical tumor samples performed at Caris Life Science (Phoenix, AZ).ResultsA total of 259 ROS1+ solid malignancies were identified from approximately 175,350 tumors that underwent next-generation sequencing (12% from targeted RNA sequencing [Archer]; 88% from whole transcriptome sequencing). ROS1+ NSCLC constituted 78.8% of the ROS1+ solid malignancies, follow by glioblastoma (GBM) (6.9%), and breast cancer (2.7%). The frequency of ROS1 fusion was approximately 0.47% among NSCLC, 0.29% for GBM, 0.04% of breast cancer. The mean tumor mutation burden for all ROS1+ tumors was 4.8 mutations/megabase. The distribution of PD-L1 (22C3) expression among all ROS1+ malignancies were 0% (18.6%), 1%-49% (29.4%), and ≥ 50% (60.3%) [for NSCLC: 0% (17.8%); 1–49% (27.7%); ≥ 50% (53.9%).The most common genetic co-alterations of ROS1+ NSCLC were TP53 (29.1%), SETD2 (7.3%), ARIAD1A (6.3%), and U2AF1 (5.6%).ConclusionsROS1+ NSCLC tumors constituted the majority of ROS1+ solid malignancies with four major fusion partners. Given that > 20% of ROS1+ solid tumors may benefit from ROS1 TKIs treatment, comprehensive genomic profiling should be performed on all solid tumors.

Differential network analysis of ROS1 inhibitors reveals lorlatinib polypharmacology through co-targeting PYK2

Multiple tyrosine kinase inhibitors (TKIs) are often developed for the same indication. However, their relative overall efficacy is frequently incompletely understood and they may harbor unrecognized targets that cooperate with the intended target. We compared several ROS1 TKIs for inhibition of ROS1-fusion-positive lung cancer cell viability, ROS1 autophosphorylation and kinase activity, which indicated disproportionately higher cellular potency of one TKI, lorlatinib. Quantitative chemical and phosphoproteomics across four ROS1 TKIs and differential network analysis revealed that lorlatinib uniquely impacted focal adhesion signaling. Functional validation using pharmacological probes, RNA interference, and CRISPR-Cas9 knockout uncovered a polypharmacology mechanism of lorlatinib by dual targeting ROS1 and PYK2, which form a multiprotein complex with SRC. Rational multi-targeting of this complex by combining lorlatinib with SRC inhibitors exhibited pronounced synergy. Taken together, we show that systems pharmacology-based differential network analysis can dissect mixed canonical/non-canonical polypharmacology mechanisms across multiple TKIs enabling the design of rational drug combinations.

56P SLC34A2-ROS1 L2026M+G2032R confers resistance to ROS1 tyrosine kinase inhibitors in Ba/F3 cells through a reduced ATP binding pocket volume

56P SLC34A2-ROS1 L2026M+G2032R confers resistance to ROS1 tyrosine kinase inhibitors in Ba/F3 cells through a reduced ATP binding pocket volume

177P Dissecting the molecular landscape of resistance to ROS1 tyrosine kinase inhibitors with improved NSCLC pre-clinical models

177P Dissecting the molecular landscape of resistance to ROS1 tyrosine kinase inhibitors with improved NSCLC pre-clinical models

Evolution of acquired resistance in a ROS1+ KRAS G12C+ NSCLC through the MAPK pathway

Patients with metastatic NSCLC bearing a ROS1 gene fusion usually experience prolonged disease control with ROS1-targeting tyrosine kinase inhibitors (TKI), but significant clinical heterogeneity exists in part due to the presence of co-occurring genomic alterations. Here, we report on a patient with metastatic NSCLC with a concurrent ROS1 fusion and KRAS p.G12C mutation at diagnosis who experienced a short duration of disease control on entrectinib, a ROS1 TKI. At progression, the patient continued entrectinib and started sotorasib, a small molecule inhibitor of KRAS p.G12C. A patient-derived cell line generated at progression on entrectinib demonstrated improved TKI responsiveness when treated with entrectinib and sotorasib. Cell-line growth dependence on both ROS1 and KRAS p.G12C was further reflected in the distinct downstream signaling pathways activated by each driver. Clinical benefit was not observed with combined therapy of entrectinib and sotorasib possibly related to an evolving KRAS p.G12C amplification identified on repeated molecular testing. This case supports the need for broad molecular profiling in patients with metastatic NSCLC for potential therapeutic and prognostic information.

Yes-associated protein 1 mediates initial cell survival during lorlatinib treatment through AKT signaling in ROS1-rearranged lung cancer.

Tyrosine kinase inhibitors (TKIs) that target the ROS proto-oncogene 1, receptor tyrosine kinase (ROS1) gene have shown dramatic therapeutic effects in patients with ROS1-rearranged non-small-cell lung cancer (NSCLC). Nevertheless, advanced ROS1-rearranged NSCLC is rarely cured as a portion of the tumor cells can survive the initial stages of ROS1-TKI treatment, even after maximum tumor shrinkage. Therefore, understanding the mechanisms underlying initial cell survival during ROS1-TKI treatment is necessary to prevent cell survival and achieve a cure for ROS1-rearranged NSCLC. In this study, we clarified the initial survival mechanisms during treatment with lorlatinib, a ROS1 TKI. First, we established a patient-derived ezrin gene-ROS1-rearranged NSCLC cell line (KTOR71). Then, following proteomic analysis, we focused on yes-associated protein 1 (YAP1), which is a major mediator of the Hippo pathway, as a candidate factor involved in cell survival during early lorlatinib treatment. Yes-associated protein 1 was activated by short-term lorlatinib treatment both in vitro and in vivo. Genetic inhibition of YAP1 using siRNA, or pharmacological inhibition of YAP1 function by the YAP1-inhibitor verteporfin, enhanced the sensitivity of KTOR71 cells to lorlatinib. In addition, the prosurvival effect of YAP1 was exerted through the reactivation of AKT. Finally, combined therapy with verteporfin and lorlatinib was found to achieve significantly sustained tumor remission compared with lorlatinib monotherapy in vivo. These results suggest that YAP1 could mediate initial cell resistance to lorlatinib in KTOR71 cells. Thus, combined therapy targeting both YAP1 and ROS1 could potentially improve the outcome of ROS1-rearranged NSCLC.

8 Oral - Safety and preliminary clinical activity of NVL-520, a highly selective ROS1 inhibitor, in patients with advanced ROS1 fusion-positive solid tumors

8 Oral - Safety and preliminary clinical activity of NVL-520, a highly selective ROS1 inhibitor, in patients with advanced ROS1 fusion-positive solid tumors

2LBA Late Breaking - Pivotal topline data from the phase 1/2 TRIDENT-1 trial of repotrectinib in patients with ROS1+ advanced non-small cell lung cancer (NSCLC)

Background: Repotrectinib is a next-generation ROS1 tyrosine kinase inhibitor (TKI) currently under evaluation in the global phase 1/2 TRIDENT-1 trial (NCT03093116). We report updated results in TKI-naïve and -pretreated patients with advanced, ROS1 fusion-positive (ROS1+) NSCLCs.

The association between ROS1 rearrangement and risk of thromboembolic events in patients with advanced non-small cell lung cancer: a multicenter study in China

BackgroundAccording to several studies, ROS1 rearrangement is associated with thrombotic risk in non-small cell lung cancer (NSCLC). However, there is no clear understanding of the predictors and prognostic impact of thromboembolic events (TEEs) in patients with advanced ROS1 rearrangement NSCLC.MethodsA total of 47 newly diagnosed advanced NSCLC patients with ROS1 rearrangement from four Chinese hospitals were retrospectively included and were evaluated for TEEs incidence, characteristics, predictors, as well as response to therapies and overall survival (OS).ResultsOf the 47 enrolled patients, 23.4% (n = 11) patients developed TEEs. Among them, 7 of 11 patients (64%) developed pulmonary embolism (PE), and 5 patients (45%) experienced recurrent TEEs. In multivariate analysis, D-dimer was associated with the occurrence of TEEs in ROS1 rearranged NSCLC (HR 1.16, 95% CI 1.08–1.23, P < 0.001). Median progression-free survival (PFS) after first-line ROS1 tyrosine kinase inhibitors (TKIs) therapy was significantly longer in patients without TEEs than in those developing TEEs (26 months vs. 12 months, P = 0.0383). Furthermore, patients with TEEs had a shorter OS period than those without TEEs (29.8 months vs. not estimable, P = 0.0647).ConclusionThe results of this multicenter study indicated that advanced NSCLC patients with ROS1 rearrangement were more likely to experience PE and TEEs recurrence. And patients with TEEs tended to have a worse prognosis. Furthermore, an elevated D-dimer level suggested a hypercoagulable state in NSCLC patients with ROS1 rearrangement.

MET gene amplification is a mechanism of resistance to entrectinib in ROS1+ NSCLC.

ROS1 tyrosine kinase inhibitors (TKIs) have demonstrated significant clinical benefit for ROS1+ NSCLC patients. However, TKI resistance inevitably develops through ROS1 kinase domain (KD) modification or another kinase driving bypass signaling. While multiple TKIs have been designed to target ROS1 KD mutations, less is known about bypass signaling in TKI-resistant ROS1+ lung cancers. Utilizing a primary, patient-derived TPM3-ROS1 cell line (CUTO28), we derived an entrectinib-resistant line (CUTO28-ER). We evaluated proliferation and signaling responses to TKIs, and utilized RNA sequencing, whole exome sequencing, and fluorescence in situ hybridization to detect transcriptional, mutational, and copy number alterations, respectively. We substantiated in vitro findings using a CD74-ROS1 NSCLC patient's tumor samples. Last, we analyzed circulating tumor DNA (ctDNA) from ROS1+ NSCLC patients in the STARTRK-2 entrectinib trial to determine the prevalence of MET amplification. CUTO28-ER cells did not exhibit ROS1 KD mutations. MET TKIs inhibited proliferation and downstream signaling and MET transcription was elevated in CUTO28-ER cells. CUTO28-ER cells displayed extrachromosomal (ecDNA) MET amplification without MET activating mutations, exon 14 skipping, or fusions. The CD74-ROS1 patient samples illustrated MET amplification while receiving ROS1 TKI. Finally, two of 105 (1.9%) entrectinib-resistant ROS1+ NSCLC STARTRK-2 patients with ctDNA analysis at enrollment and disease progression displayed MET amplification. Treatment with ROS1-selective inhibitors may lead to MET-mediated resistance. The discovery of ecDNA MET amplification is noteworthy, as ecDNA is associated with more aggressive cancers. Following progression on ROS1-selective inhibitors, MET gene testing and treatments targeting MET should be explored to overcome MET-driven resistance.

105P Pan-tumor survey of ROS1 fusions detected by next-generation RNA sequencing

Two ROS1 tyrosine kinase inhibitors have been approved for ROS1 fusion-positive (ROS1+) non-small cell lung cancer (NSCLC). We performed a pan-tumor analysis of the incidence and characteristics of ROS1 fusions across all solid tumors.