Mechanisms of primary and secondary resistance to RET inhibitors in patients with RET-positive advanced NSCLC

Background: RET fusions are found in 1-2% of patients (pts) with advanced non-small cell lung cancer (aNSCLC). Targeted therapy with RET inhibitors (RETi) significantly improved prognosis. Molecular mechanisms of resistance are still incompletely characterized. Methods: This multicentric retrospective study included 24 centres. Eligible pts had a RET+ aNSCLC, were treated with a RETi and had at least one molecular profile by next-generation sequencing (NGS), performed before and/or after RETi, on tissue and/or plasma samples. Primary resistance under RETi was defined as disease progression (PD) within 6 months of therapy. Results: 95 patients were included with 112 biopsies: 93 at baseline, 19 at PD. 17 patients had paired NGS (baseline and PD). Median age was 65 years (range 56-72);62% were female, 54% were never smokers, 17% had brain metastasis (BM) at diagnosis. 55 patients received pralsetinib, 36 selpercatinib, 4 other RETi. Overall, median PFS under RETi was 17.1 months (95%CI 12.6-28). Primary resistance to RETi occurred in 22 (23%) patients. Primary resistant versus durable responders to RETi had non-adenocarcinoma histology in 9% vs 46% (p=0.61), smoking history in 57% vs 40% (p=0.21), BM in 5% vs 21% (p=0.1), TP53 mutations in 37% vs 22% (p=0.23). KRAS G12V mutation and SMARCA4 alterations were found only in poor responders (4.5% vs 0%, p=0.2;and 25% vs 0%, p=0.04, respectively). Among biopsies at PD (N=19, 13 liquid and 6 tissue biopsies), 7/13 (54%) liquid biopsies failed due to insufficient ctDNA. In 12 evaluable pts, 3 (25%) acquired secondary RET mutations (2 G810S and 1 S904F), 3 (25%) had novel RET rearrangements (2 in intron 11, 1 RET-DOCK1, 1 RET-CSGALNACT2) and 3 (25%) pts had off-target alterations (2 MET and 1 MYC amplification). Three pts (25%) developed novel TP53 mutations, while 3 (25%) had no novel identifiable alterations at PD. Conclusions: SMARCA4 and KRAS co-mutations may have a role in primary resistance to RETi. Secondary RET mutations, novel RET rearrangements and MET/MYC amplifications were identified after treatment with RETi. More than half of pts had insufficient ctDNA at PD, making tissue biopsy essential to identify resistance mechanisms. Legal entity responsible for the study: Institut Gustave Roussy. Funding: Has not received any funding. Disclosure: V. Fallet: Financial Interests, Personal, Advisory Board: AstraZeneca, BMS, Takeda, Roche, Pfizer, Sanofi, Sandoz, Jansen;Financial Interests, Personal, Invited Speaker: AstraZeneca, BMS, Takeda, Pfizer, MSD;Financial Interests, Personal, Expert Testimony: GSK, Boehringer. C. Audigier-Valette: Financial Interests, Personal, Advisory Role: AbbVie, AstraZeneca, Boehringer Ingelheim, Bristol Myers Squibb, Ipsen, Eli Lilly, Novartis, Pfizer, and Roche. A. Russo: Financial Interests, Personal, Advisory Board: Pfizer, AstraZeneca, MSD, Novartis;Financial Interests, Personal, Writing Engagements: AstraZeneca, Novartis. A. Calles Blanco: Financial Interests, Personal, Advisory Board: AstraZeneca, Boehringer Ingelheim, Pfizer, Roche, Lilly, Merck Sharp & Dohme, Novartis, Bristol-Myers Squibb, Takeda, Sanofi;Financial Interests, Personal, Other, Speaker honoraria: Bayer;Financial Interests, Institutional, Research Grant, Drug-only for Investigator-initiated trial: Merck Sharp & Dohme. P. Iranzo Gomez: Financial Interests, Personal, Advisory Role: Bristol-Myers Squibb Recipient, F. Hoffmann, La Roche AG, Merck Sharp & Dohme, Boehringer Ingelheim, MSD Oncology, Rovi, Yowa Kirin, Grunenthal Pharma S.A., Pfizer. M. Tagliamento: Financial Interests, Personal, Other, medical writer: Novartis, Amgen;Financial Interests, Personal, Invited Speaker, travel/accommodation: Roche, Bristol-Myers Squibb, AstraZeneca, Takeda. L. Mezquita: Financial Interests, Personal, Advisory Board: Takeda, AstraZeneca, Roche;Financial Interests, Personal, Invited Speaker: Roche, BMS, AstraZeneca, Takeda;Financial Interests, Personal, Research Grant, SEOM Beca Retorno 2019: BI;Financial Interests, Personal, Research Grant, ESMO TR Research Fellowship 2019: BMS;Financial Interests, Institutional, Research Grant, COVID research Grant: Amgen;Financial Interests, Institutional, Invited Speaker: Inivata, Stilla. C. Lindsay: Financial Interests, Institutional, Principal Investigator: Roche, Amgen, BI;Financial Interests, Personal, Advisory Role: CBPartners, Amgen. S. Ponce: Financial Interests, Institutional, Principal Investigator: Merck Sharp and Dohme, F. Hoffmann-La Roche, Foundation Medicine, PharmaMar. Personal fees: Merck Sharp and Dohme, Bristol-Myers Squibb, F. Hoffmann-La Roche, Foundation Medicine, AstraZeneca, Boehringer Ingelheim, Eli Lilly, Pfizer, Amgen, Celgene.;Financial Interests, Personal, Advisory Board: Merck Sharp and Dohme, Bristol-Myers Squibb, F. Hoffmann-La Roche, Foundation Medicine, AstraZeneca, Boehringer Ingelheim, Eli Lilly, Pfizer, Amgen, Celgene.;Non-Financial Interests, Personal, Other: Merck Sharp and Dohme, Bristol-Myers Squibb, F. Hoffmann-La Roche. M. Aldea: Financial Interests, Personal, Invited Speaker, travel/accommodation: Sandoz. All other authors have declared no conflicts of interest.

Evaluation of COVID-19 impact on DELAYing diagnostic-therapeutic pathways of lung cancer patients in Italy (COVID-DELAY study): fewer cases and higher stages from a real-world scenario.

INTRODUCTION: COVID-19 has disrupted the global health care system since March 2020. Lung cancer (LC) patients (pts) represent a vulnerable population highly affected by the pandemic. This multicenter Italian study aimed to evaluate whether the COVID-19 outbreak had an impact on access to cancer diagnosis and treatment of LC pts compared with pre-pandemic time. METHODS: Consecutive newly diagnosed LC pts referred to 25 Italian Oncology Departments between March and December 2020 were included. Access rate and temporal intervals between date of symptoms onset and diagnostic and therapeutic services were compared with the same period in 2019. Differences between the 2 years were analyzed using the chi-square test for categorical variables and the Mann-Whitney U test for continuous variables. RESULTS: A slight reduction (-6.9%) in newly diagnosed LC cases was observed in 2020 compared with 2019 (1523 versus 1637, P = 0.09). Newly diagnosed LC pts in 2020 were more likely to be diagnosed with stage IV disease (P < 0.01) and to be current smokers (someone who has smoked more than 100 cigarettes, including hand-rolled cigarettes, cigars, cigarillos, in their lifetime and has smoked in the last 28 days) (P < 0.01). The drop in terms of new diagnoses was greater in the lockdown period (percentage drop -12% versus -3.2%) compared with the other months included. More LC pts were referred to a low/medium volume hospital in 2020 compared with 2019 (P = 0.01). No differences emerged in terms of interval between symptoms onset and radiological diagnosis (P = 0.94), symptoms onset and cytohistological diagnosis (P = 0.92), symptoms onset and treatment start (P = 0.40), and treatment start and first radiological revaluation (P = 0.36). CONCLUSIONS: Our study pointed out a reduction of new diagnoses with a shift towards higher stage at diagnosis for LC pts in 2020. Despite this, the measures adopted by Italian Oncology Departments ensured the maintenance of the diagnostic-therapeutic pathways of LC pts.

Evaluation of COVID-19 impact on DELAYing diagnostic-therapeutic pathways of lung cancer patients in Italy: Real-world evidence from the COVID-DELAY study

Background: The coronavirus disease 2019 (COVID-19) had an unprecedent impact on the global health care system since March 2020. Lung cancer (LC) patients (pts) represent a vulnerable population, and diagnostic/therapeutic delays might affect the years to come. Aim of the multicenter, real-world, Italian COVID-DELAY study was to evaluate how the 2020 COVID-19 pandemic impacted on LC pts' access to diagnosis and treatment compared to pre-pandemic time. Patients and methods: All consecutive newly diagnosed LC pts referred to 25 Italian Oncology Departments between March and December 2020 were reviewed. Monthly access rate and temporal intervals between date of symptom onset, diagnosis and treatment start were analyzed and compared to the same period of 2019. Differences between the two years were analyzed using Fisher's exact test or chi-square test for categorical variables and unpaired Student t test, or the Mann-Whitney U test for continuous variables. Results: Less LC cases (1523 vs 1637, -6.9%) were diagnosed during the 2020 pandemic compared to 2019. LC pts in 2020 were more likely to be diagnosed with stage IV disease (p < 0.01) and to be current smokers (p < 0.01). A major drop of new LC cases was seen during the lockdown period (percentage drop -13.2% vs -5.1%) compared to the other months included. Moreover, a geographic migration was observed with more LC patients referring to low/ medium volume hospital in 2020 compared to 2019 (p = 0.01). Looking at pts management, no differences emerged in terms of interval between symptom onset and radiological diagnosis (p = 0.94), symptom onset and cytohistological diagnosis (p = 0.92), symptoms onset and treatment start (p = 0.40), treatment start and first radiological revaluation (p = 0.36). However, less LC patients were treated in the context of clinical trials during 2020 (5% vs 7%, p = 0.07). Conclusions: Our study pointed out a decrease of new LC cases and a shift towards a higher stage at diagnosis in 2020. Despite this, the efforts put in place by the Italian Oncology Departments ensured the maintenance of the diagnostic-therapeutic pathways of LC patients.