Lung cancer

Lung cancer is one of the most frequently diagnosed cancers and the leading cause of cancer-related deaths worldwide with an estimated 2 million new cases and 1·76 million deaths per year. Substantial improvements in our understanding of disease biology, application of predictive biomarkers, and refinements in treatment have led to remarkable progress in the past two decades and transformed outcomes for many patients. This seminar provides an overview of advances in the screening, diagnosis, and treatment of non-small-cell lung cancer and small-cell lung cancer, with a particular focus on targeted therapies and immune checkpoint inhibitors.

Abstract LB043: Efficacy of Lorlatinib in Treatment-Naïve Patients (pts) With ALK-Positive Advanced Non-Small Cell Lung Cancer (NSCLC) in Relation to EML4-ALK Variant Type and ALK Mutations

BACKGROUND: Lorlatinib, a 3rd generation ALK tyrosine kinase inhibitor, has shown overall and intracranial activity in ALK+ advanced NSCLC. In the randomized, multicenter, phase 3 study in pts with previously untreated ALK+ advanced NSCLC (CROWN; NCT03052608), lorlatinib resulted in a statistically significant and clinically meaningful improvement in progression-free survival (PFS) vs crizotinib.1 To identify molecular correlates of response, we performed molecular profiling of circulating free DNA (cfDNA) and tumor tissue.

METHODS: Plasma and tumor tissue samples were available from 130 and 118 pts in the lorlatinib arm, and from 125 and 104 pts in the crizotinib arm, respectively. Plasma DNA was analyzed for ALK fusions and mutations by next-generation sequencing (NGS; Guardant360, Guardant Health, Inc., Redwood City, CA, USA); tumor tissue DNA was analyzed with an ALK-mutation focused NGS panel (MolecularMD, Portland, OR, USA). Objective response rate (ORR), duration of response (DOR), and PFS were evaluated by blinded independent central review according to EML4-ALK variant type and ALK resistance mutation status.

RESULTS: At screening, 19 ALK missense mutations and 1 deletion were detected in plasma of 11 pts (5 and 6 in the lorlatinib and crizotinib arms, respectively). Most pts harbored 1 mutation, but 3 pts harbored ≥3 mutations. ALK fusions were detected in plasma of 48% of pts. EML4-ALK variants 1, 2, and 3 were detected in 14.6%, 5.4%, and 13.8% and in 20.0%, 1.6%, and 16.8% of pts, in the lorlatinib and crizotinib arms, respectively. Variants 4, 5, 7, and 8 were detected in 11.5% and 7.2% of pts, and less frequent fusion partners in 1.5% and 3.2% of pts, respectively. ORRs were generally higher in the lorlatinib arm vs the crizotinib arm, regardless of variant subtypes and/or mutational status, with no striking differences between EML4-ALK variants 1, 2, and 3 (range, 72% to 86% for lorlatinib and 50% to 76% for crizotinib). Median DOR and PFS were not reached for variants 1 and 3 in the lorlatinib arm, and ranged from 5.7 to 6.5 months, and from 7.4 to 7.6 months in the crizotinib arm, respectively.

CONCLUSION: Pts with untreated ALK+ advanced NSCLC had higher ORRs and potentially longer DOR and PFS across predefined biomarker subgroups when treated with lorlatinib compared with crizotinib in a phase 3 CROWN study. Based on pretreatment cfDNA analysis, lorlatinib led to similar clinical benefit regardless of the type of EML4-ALK variant or presence of ALK kinase mutations.

REFERENCE: 1. Shaw AT, et al. N Engl J Med. 2020;383:2018-2029.

Citation Format: Alessandra Bearz, Jean-François Martini, Jacek Jassem, Sang-We Kim, Gee-Chen Chang, Alice Shaw, Deborah Shepard, Elisa Dall'O', Anna Polli, Holger Thurm, Gerard Zalcman, Maria Rosario Garcia Campelo, Konstantin Penkov, Hidetoshi Hayashi, Benjamin J. Solomon. Efficacy of Lorlatinib in Treatment-Naïve Patients (pts) With ALK-Positive Advanced Non-Small Cell Lung Cancer (NSCLC) in Relation to EML4-ALK Variant Type and ALK Mutations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB043.

Immunotherapy in oncogene addicted non-small cell lung cancer

The use of immune checkpoint inhibitors (ICIs) targeting the programmed cell death-1 (PD-1) and programmed cell death ligand-1 (PD-L1) has led to notable changes in treatment strategies for patients with advanced non-small cell lung cancer (NSCLC) and now forms a part of standard of care treatment in patients with advanced disease. However, most patients do not respond to ICI monotherapy, which may be explained by significant variations in efficacy according to different immune and molecular profiles in tumours. Improved response rates have been observed in smokers and are associated with tumors that have high mutation loads, with a higher tendency to form neoantigens. This premise itself defies the eventual significance of ICIs for oncogene-driven NSCLC, which in general are more common in never smokers and potentially have reduced capacity for neoantigen formation. Furthermore, pivotal trials investigating ICIs in advanced NSCLC have usually excluded patients with oncogenic drivers, hence the outcome of these agents in this population is poorly characterized. In this article, we aim to review the most current evidence, encompassing clinical and preclinical data focused on a wide range of oncogene-addicted NSCLCs.

Identification of good and poor prognosis HPV associated oropharyngeal cancer based on CD103 immune cell expression in patients treated with cetuximab and radiotherapy on TROG 12.01 and De-ESCALaTE randomized trials

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Background: Trials in human papilloma virus associated oropharyngeal squamous cell carcinoma (HPVOPSCC), substituting cetuximab (CETUX) for cisplatin (CIS) with radiotherapy (RT), resulted in decreased efficacy without improved toxicity or symptom burden. We reported that high intratumoral immune cell (ITIC) CD103 expression (> 30%), a marker of tissue-resident memory T cells, is associated with better prognosis in unselected patients with HPVOPSCC treated with CIS/RT. In this study our aim was to determine whether low risk HPVOPSCC patients treated with CETUX/RT with high CD103 have a superior prognosis. Methods: TROG 12.01 and De-ESCALaTE are randomised multicentre trials that compared 70Gy RT/CETUX with 70Gy RT/CIS (weekly in TROG 12.01, 3-weekly in De-ESCALaTE) in patients with HPVOPSCC, low risk by Ang criteria: AJCC 7th Stage III (excluding T1-2N1) or stage IV (excluding N2b-c if smoking history > 10 pack years and/or distant metastases). In TROG 12.01 T4 and/or N3 patients were also excluded. Eligible patients required tumor samples available for immune cell quantification on immunohistochemistry. Data from the two trials were pooled, with analyses performed in eligible randomised patients who commenced treatment. The primary endpoint was failure-free survival (FFS) in patients receiving CETUX/ RT comparing CD103 ITIC > 30% (high) vs. < 30% (low). High/low CD103 were compared using Cox model adjusting for age, stage and trial. Results: Samples for CD103 testing were available in 159/182 patients on TROG 12.01 and 145/334 on De-ESCALaTE. ITIC CD103 expression was high in 26% of patients. The median follow-up was 3.2 years. The 3 -year failure-free survival rates in patients treated with CETUX/RT were 92% (95% CI: 78-97%) in high CD103 and 74% (95% CI: 64-82%) in low CD103, adjusted HR 0.25 (95% CI: 0.14-0.44); p < 0.001. The 3 -year overall survival (OS) in patients treated with CETUX/RT were 100% in high CD103 and 86% (95% CI: 76-92%) in low CD103, p < 0.001. Superior FFS in the high CD103 group was independent of stage. In patients treated with CIS/RT there was no significant difference in FFS (3-year 86% in high CD103 and 90% in low CD103; p = 0.55) or in OS (3-year 100% in high CD103 and 95% in low CD103; p = 0.14). The increase in failures in the low CD103 patients treated with CETUX/RT was evenly split between distant and locoregional failures. Conclusions: ITIC CD103 separates CETUX/RT treated low risk HPVOPSCC into excellent and poor prognosis subgroups. In a low risk population CIS/RT achieves excellent outcomes in both high and low ITIC CD103 groups. The high ITIC CD103 population is a rational target for future de-intensification trials.

Early circulating tumor (ct) DNA dynamics and efficacy of lorlatinib: Analysis from the CROWN study

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Background: Lorlatinib, a third-generation ALK tyrosine kinase inhibitor, significantly improved progression-free survival (PFS) and overall/intracranial responses vs crizotinib in patients (pts) with previously untreated ALK-positive advanced non-small cell lung cancer (NSCLC) in the ongoing randomized Phase 3 CROWN study (NCT03052608). To identify whether additional molecular biomarker analysis correlated with efficacy, we evaluated early ctDNA dynamics compared with clinical outcomes. Methods: Plasma samples were prospectively collected at screening (SC), week 4 (cycle 2, day 1 [C2D1]), week 24 (C7D1), and end of treatment for ctDNA analysis. ctDNA was analyzed using Guardant360CDx (Guardant Health, Inc., Redwood City, CA, USA). Mean variant allele fraction (VAF) of ALK alterations (fusions and/or mutations) and overall detected alterations at each time point and longitudinal mean change (dVAF) as (VAFC2D1) – (VAFSC) were calculated; dVAF <0 indicated decreased ctDNA at week 4. Objective tumor response and PFS were evaluated according to dVAF. These analyses were repeated vs ctDNA results at week 24. Additional correlation analyses between depth of molecular response and/or ctDNA clearance and clinical outcomes are ongoing. Results: Paired samples were available at SC and week 4 from 232 of 255 pts included in the ctDNA analysis: 118/130 (90.8%) in the lorlatinib arm and 114/125 (91.2%) in the crizotinib arm. ALK alterations were detected in 122/232 (52.6%) pts at SC (62/118 [52.5%] from the lorlatinib arm) but only 19/232 (8.2%) at week 4 (8/118 [6.8%] from the lorlatinib arm). Mean VAF of ALK alterations at week 4 was significantly decreased compared with SC in both treatment arms (lorlatinib -1.54, crizotinib -1.25; both P<0.0001; P=0.4239 between arms). In the lorlatinib arm, mean VAF at week 4 was significantly decreased compared with SC in pts with a complete or partial response (dVAF -1.53; n=47; P<0.0001), or stable disease (dVAF -1.37; n=12; P=0.0304). Similar results were observed in the crizotinib arm. In pts with dVAF <0 for ALK alterations, mean percent change from screening in tumor size was -40.8% with lorlatinib (n=59) and -38.7% with crizotinib (n=58). Only 2 pts had dVAF ≥0, both from the crizotinib arm. Median PFS for pts with dVAF <0 for ALK alterations was not reached in the lorlatinib arm (n=62), and was 7.4 months (95% CI, 7.2–9.3) in the crizotinib arm (n=58). Similar response and PFS data were observed in the analysis of dVAF for ALK alterations at week 24. Conclusions: Early ctDNA dynamics may predict lorlatinib efficacy in pts with previously untreated ALK-positive NSCLC. The magnitude of reduction in ctDNA at 4 weeks may be associated with better responses and potentially longer PFS. These findings further support the utility of dynamic ctDNA monitoring in ALK-positive NSCLC. Reference: Shaw AT, et al. N Engl J Med. 2020;383:2018-2029. Clinical trial information: NCT03052608.

Response to selpercatinib versus prior systemic therapy in patients (pts) with RET fusion+ non-small-cell lung cancer (NSCLC)

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Background: Selpercatinib, a first-in-class highly selective, potent, CNS-active RET kinase inhibitor, is approved in multiple countries for treatment of RET fusion+ lung or thyroid cancers. Selpercatinib demonstrated durable antitumor activity in previously treated pts with RET fusion+ NSCLC in an ongoing Phase 1/2 trial, LIBRETTO-001 (Besse et al., ASCO 2021). Methods: Pts with RET fusion+ NSCLC enrolled in the global, multicenter, LIBRETTO-001 trial (NCT03157128; 16 countries, 89 sites). Primary endpoint was objective response rate (ORR). Secondary endpoints included progression-free survival, duration of response, and safety. This post-hoc intrapatient analysis was based on a 30 March 2020 data cutoff date. Historical physician-reported best overall response (BOR) from last systemic therapy received prior to enrollment was compared with selpercatinib BOR by independent review committee per RECIST v1.1, with each patient serving as his/her own control. Results: In efficacy-evaluable pts (N = 218) who previously received platinum-based chemotherapy (chemo), median pt age was 61 years, the majority with ECOG of 0/1 (37%/61%), with a median of 2 (range: 1-15) prior systemic therapies. Overall, 57% of patients responded to selpercatinib while 16% responded to the immediate prior therapy. ORR improvements with selpercatinib were observed regardless of prior therapy: chemotherapy + immune checkpoint inhibitor (ICI) (57% vs 14%), single-agent ICI (48% vs 3%), or chemotherapy (58% vs 15%). A total of 108 patients (49%) did not respond to immediate prior therapy but responded to selpercatinib. Fewer patients had progressive disease as their BOR with selpercatinib (2%) compared to the immediate prior therapy (28%). The median duration of therapy for selpercatinib was notably extended compared with that of the immediate prior therapy (11.8 vs. 3.4 months, respectively). Conclusions: In pts with RET fusion+ NSCLC treated on LIBRETTO-001, systemic therapies administered prior to enrollment achieved less meaningful clinical benefit than selpercatinib. Selpercatinib demonstrated consistent efficacy regardless of the type of prior therapy. Clinical trial information: NCT03157128.

Updated overall efficacy and safety of selpercatinib in patients (pts) with RET fusion+ non-small cell lung cancer (NSCLC)

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Background: Selpercatinib, a first-in-class highly selective and potent, CNS-active RET kinase inhibitor, is approved in multiple countries for treatment of RET fusion+ lung or thyroid cancers. Here we report an update of efficacy and safety results which provide a longer follow up and increased number of patients (safety population: N = 345 vs N = 329). Methods: Pts with RET fusion+ NSCLC enrolled in the global, multicenter, ongoing LIBRETTO-001 trial (NCT03157128; 16 countries, 89 sites) were included in this analysis. Pts with the opportunity to be followed ≥6 months from their first dose were included in the efficacy-evaluable population for these analyses. Integrated analysis set (IAS) included 218 NSCLC pts with prior platinum-chemotherapy. Primary analysis set (PAS) was a subset of the IAS and included the first 105 consecutively enrolled pts. The treatment-naïve population included 48 efficacy-evaluable pts. Primary endpoint was objective response rate (ORR, RECIST v1.1) by independent review committee (IRC). Secondary endpoints included ORR by investigator, duration of response (DoR), progression-free survival (PFS), clinical benefit rate (CBR; CR+PR+SD ≥16 weeks), and safety. Safety population (N = 345) included all pts with NSCLC who received ≥1 selpercatinib dose by data cutoff (30 Mar 2020). Results: In pts with prior treatment (N = 218) and treatment-naïve (N = 48) pts, 56% and 60% were female, with a median pt age of 61 and 64 years, respectively. The ORR with selpercatinib was 57% in the IAS, 64% in the PAS, and 85% in the treatment-naïve population (Table). In both the IAS and PAS, the median DoR was 17.5 months, median PFS was 19.3 months at median follow-up of 12.0 and 15.7 months, respectively (Table). The most common treatment-emergent adverse events (TEAEs) reported in ≥25% of pts were dry mouth, diarrhea, hypertension, increased ALT/AST, edema peripheral, and fatigue. Twenty-five pts (7%) permanently discontinued due to TEAEs, with 10 pts (3%) discontinuing selpercatinib due to treatment-related AEs as per investigator. Conclusions: In this updated data set, selpercatinib continued to demonstrate durable antitumor activity in pts with RET-fusion+ NSCLC. Selpercatinib was well-tolerated with a safety profile consistent with previous reports. A global, randomized, phase 3 trial (LIBRETTO-431) evaluating selpercatinib compared with standard frontline therapy is ongoing. Clinical trial information: NCT03157128. [Table: see text]

Intracranial and extracranial efficacy of lorlatinib in patients with ALK-positive non-small-cell lung cancer previously treated with second-generation ALK TKIs

BACKGROUND

Lorlatinib, a potent, brain-penetrant, third-generation anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitor (TKI), has substantial activity against ALK-positive non-small-cell lung cancer (NSCLC). This study assessed the overall, intracranial, and extracranial efficacy of lorlatinib in ALK-positive NSCLC that progressed on second-generation ALK TKIs.

PATIENTS AND METHODS

In the ongoing phase II study (NCT01970865), patients with ALK-positive advanced NSCLC treated with ≥1 prior second-generation ALK TKI ± chemotherapy were enrolled in expansion cohorts (EXP) based on treatment history. Overall, intracranial and extracranial antitumor activity were assessed independently per modified Response Evaluation Criteria in Solid Tumors (RECIST) v1.1.

RESULTS

Of the 139 patients with ≥1 prior second-generation ALK TKI (EXP3B-5), 28 received one prior second-generation ALK TKI (EXP3B), 65 two prior ALK TKIs (EXP4), and 46 three prior ALK TKIs (EXP5). In EXP3B-5, the objective response rate (ORR) [95% confidence intervals] was 39.6% (31.4-48.2), intracranial ORR (IC-ORR) was 56.1% (42.4-69.3), extracranial ORR (EC-ORR) was 36.7% (28.7-45.3), median duration of response (DOR) was 9.6 months [5.6-16.7; IC-DOR, 12.4 (6.0-37.1); EC-DOR, 9.7 (6.1-33.3)], median progression-free survival was 6.6 (5.4-7.4) months, and median overall survival was 20.7 months (16.1-30.3). In EXP3B, the ORR was 42.9% (24.5-62.8), the IC-ORR was 66.7% (29.9-92.5), and the EC-ORR was 32.1% (15.9-52.4). In EXP4 and EXP5, the ORR was 38.7% (29.6-48.5), the IC-ORR was 54.2% (39.2-68.6), and the EC-ORR was 37.8% (28.8-47.5).

CONCLUSIONS

Lorlatinib had clinically meaningful intracranial and extracranial antitumor activity in the post-second-generation ALK TKI setting, with elevated intracranial versus extracranial ORR, particularly in patients with fewer lines of therapy.

An inverse stage-shift model to estimate the excess mortality and health economic impact of delayed access to cancer services due to the COVID-19 pandemic

AIM

Decreased cancer incidence and reported changes to clinical management indicate that the COVID-19 pandemic has delayed cancer diagnosis and treatment. This study aimed to develop and apply a flexible model to estimate the impact of delayed diagnosis and treatment on survival outcomes and healthcare costs based on a shift in the disease stage at treatment initiation.

METHODS

A model was developed and made publicly available to estimate population-level health economic outcomes by extrapolating and weighing stage-specific outcomes by the distribution of stages at treatment initiation. It was applied to estimate the impact of 3- and 6-month delays based on Australian data for stage I breast cancer, colorectal cancer, and lung cancer patients, and for T1 melanoma. Two approaches were explored to estimate stage shifts following a delay: (a) based on the relation between time to treatment initiation and overall survival (breast, colorectal, and lung cancer), and (b) based on the tumor growth rate (melanoma).

RESULTS

Using a conservative once-off 3-month delay and considering only shifts from stage I/T1 to stage II/T2, 88 excess deaths and $12 million excess healthcare costs were predicted in Australia over 5 years for all patients diagnosed in 2020. For a 6-month delay, excess mortality and healthcare costs were 349 deaths and $46 million over 5 years.

CONCLUSIONS

The health and economic impacts of delays in treatment initiation cause an imminent policy concern. More accurate individual patient data on shifts in stage of disease during and after the COVID-19 pandemic are critical for further analyses.

First-Line Lorlatinib or Crizotinib in Advanced ALK-Positive Lung Cancer

BACKGROUND

Lorlatinib, a third-generation inhibitor of anaplastic lymphoma kinase (ALK), has antitumor activity in previously treated patients with ALK-positive non-small-cell lung cancer (NSCLC). The efficacy of lorlatinib, as compared with that of crizotinib, as first-line treatment for advanced ALK-positive NSCLC is unclear.

METHODS

We conducted a global, randomized, phase 3 trial comparing lorlatinib with crizotinib in 296 patients with advanced ALK-positive NSCLC who had received no previous systemic treatment for metastatic disease. The primary end point was progression-free survival as assessed by blinded independent central review. Secondary end points included independently assessed objective response and intracranial response. An interim analysis of efficacy was planned after approximately 133 of 177 (75%) expected events of disease progression or death had occurred.

RESULTS

The percentage of patients who were alive without disease progression at 12 months was 78% (95% confidence interval [CI], 70 to 84) in the lorlatinib group and 39% (95% CI, 30 to 48) in the crizotinib group (hazard ratio for disease progression or death, 0.28; 95% CI, 0.19 to 0.41; P<0.001). An objective response occurred in 76% (95% CI, 68 to 83) of the patients in the lorlatinib group and 58% (95% CI, 49 to 66) of those in the crizotinib group; among those with measurable brain metastases, 82% (95% CI, 57 to 96) and 23% (95% CI, 5 to 54), respectively, had an intracranial response, and 71% of the patients who received lorlatinib had an intracranial complete response. The most common adverse events with lorlatinib were hyperlipidemia, edema, increased weight, peripheral neuropathy, and cognitive effects. Lorlatinib was associated with more grade 3 or 4 adverse events (mainly altered lipid levels) than crizotinib (in 72% vs. 56%). Discontinuation of treatment because of adverse events occurred in 7% and 9% of the patients, respectively.

CONCLUSIONS

In an interim analysis of results among patients with previously untreated advanced ALK-positive NSCLC, those who received lorlatinib had significantly longer progression-free survival and a higher frequency of intracranial response than those who received crizotinib. The incidence of grade 3 or 4 adverse events was higher with lorlatinib than with crizotinib because of the frequent occurrence of altered lipid levels. (Funded by Pfizer; CROWN ClinicalTrials.gov number, NCT03052608.).

Phase III study of selpercatinib versus chemotherapy ± pembrolizumab in untreated RET positive non-small-cell lung cancer

Selpercatinib, a novel, highly selective and potent, inhibitor of RET, demonstrated clinically meaningful antitumor activity with manageable toxicity in heavily pretreated and treatment-naive RET fusion-positive non-small-cell lung cancer patients in a Phase I/II clinical trial. LIBRETTO-431 (NCT04194944) is a randomized, global, multicenter, open-label, Phase III trial, evaluating selpercatinib versus carboplatin or cisplatin and pemetrexed chemotherapy with or without pembrolizumab in treatment-naive patients with locally advanced/metastatic RET fusion-positive nonsquamous non-small-cell lung cancer. The primary end point is progression-free survival by independent review. Key secondary end points include overall survival, response rate, duration of response and progression-free survival. Clinical trial registration: NCT04194944 (ClinicalTrials.gov).

Abstract CT214: CANOPY-1: Safety run-in results from phase (ph) 3 study of canakinumab (CAN) or placebo (PBO) in combination (comb) with pembrolizumab (PEM) plus platinum-based doublet chemotherapy (Ctx) as 1st line therapy in patients (pts) with advanced or metastatic NSCLC

Cytokine interleukin-1β (IL-1β) has multiple pro-tumorogenic effects on tumor microenvironment, thereby promoting carcinogenesis, tumor invasiveness, and immunosuppression. CAN is a selective IL-1β inhibitor that aims to target tumor-promoting inflammation to reduce immune suppression, thereby potentiating effects of immunotherapy with PD-1 inhibitors such as PEM. Ph 3 CANTOS study has shown IL-1β inhibition with CAN was associated with reduced incidence of lung cancer (LC) and LC mortality in pts with atherosclerosis, providing a rationale to investigate therapeutic role of CAN in LC. CANOPY-1 (NCT03631199) is a PBO-controlled, double-blind, randomized, ph 3 trial designed to evaluate efficacy and safety of PEM + Ctx ± CAN in tx naive pts with stage IIIB/IIIC (not eligible for definitive chemo-radiation curative tx) or stage IV squamous and nonsquamous NSCLC. The study was divided into 2 parts: part 1 is open labelled, safety run-in part where pts received CAN 200 mg s.c Q3W + PEM 200 mg i.v Q3W + platinum-based Ctx (as induction during first 4 cycles only); Cohort A (A, non-squamous), carboplatin + pemetrexed; Cohort B (B, non-squamous), cisplatin + pemetrexed; Cohort C (C, squamous or non-squamous), carboplatin + paclitaxel. Part 2 is randomized and evaluates efficacy and safety of CAN comb regimen vs PBO comb regimen. Primary objective of safety run-in part: recommended ph 3 dose regimen (RP3R) of CAN comb. Secondary objectives: ORR, DCR, DOR, safety, PK, and immunogenicity. As of 14 May 2019 (follow-up of ≥42 days from C1D1 unless pt discontinued earlier), 10 pts in A, 11 pts in B, and 9 pts in C were treated, of which 73% were male, median age was 63 yrs. In total, 24/30 (80%) pts enrolled were still receiving tx; primary reason for tx discontinuation was progressive disease (3 pts in A and 1 pt each in B and C) and 1 pt died due to study indication. 1 pt reported DLT during first 42 days of study tx (C: grade 3 hepatitis, not related to CAN). RP3R of CAN in comb with standard dose PEM + Ctx was 200 mg SC Q3W based on Bayesian logistic regression model (BLRM). Serious AEs regardless of causality were reported in 8 (27%) pts (2 pts in A and 3 pts each in B and C), none of which were considered to be related to CAN. Most common AEs (≥20%, any grade) across all cohorts (n=30) were nausea (37%), vomiting (30%), constipation and fatigue (each 23%), and neutrophil count decrease (20%). 14 pts (47%) experienced grade 3 AEs and 1 pt experienced grade 4 AE (cardiac tamponade [unrelated]). No fatal serious AEs were reported. AEs leading to discontinuation of one of the study drugs were reported in 3 (10%) pts (hepatitis, peripheral neuropathy, and polyneuropathy) but none were CAN related. AEs leading to dose reduction and dose interruption of one of study drugs were reported in 3 (10%) pts and 5 (17%) pts, respectively. Only 1 DLT was reported with CAN + PEM + Ctx. Based on BLRM and all relevant clinical data, the RP3R of CAN as 200 mg SC Q3W comb was considered safe and well tolerated. Enrollment for the randomized part is completed.

Citation Format: Bruce E. Johnson, Tae Min Kim, T. Jeroen N. Hiltermann, Fabrice Barlesi, Christian Grohe, Yasushi Goto, Orvar Gunnarsson, Tobias Overbeck, Noemi Reguart, Martin Wermke, Gilberto Castro Castro, Enriqueta Felip, Alastair Greystoke, Benjamin J. Solomon, Stephanie Deudon, Anne-Laure Louveau, Vanessa Passos, Daniel SW Tan. CANOPY-1: Safety run-in results from phase (ph) 3 study of canakinumab (CAN) or placebo (PBO) in combination (comb) with pembrolizumab (PEM) plus platinum-based doublet chemotherapy (Ctx) as 1st line therapy in patients (pts) with advanced or metastatic NSCLC [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT214.

Abstract CT286: CANOPY program clinical trials: Canakinumab (Cana) in patients (pts) with non-small cell lung cancer (NSCLC)

Background: In the CANTOS study, treatment (tx) with Cana (selective IL-1β inhibitor) was associated with reduced incidence and mortality of NSCLC in stable post-myocardial infarction pts with elevated high-sensitivity C-reactive protein levels. The results provided a rationale to investigate the therapeutic role of Cana in NSCLC. Methods: The phase (ph) 2, open-label CANOPY-N study (NCT03968419) is evaluating Cana or pembrolizumab (pembro) alone or in combination as neoadjuvant tx in stage IB-IIIA, tx-naive NSCLC pts eligible for primary resection (except N2 and T4 tumors) with planned surgery in 4-6 weeks (wks) from the 1st dose of study tx. Pts (~110) are randomized 2:2:1 to Cana (2 doses 200 mg SC Q3W), Cana + pembro, or pembro (2 doses 200 mg iv Q3W) for 2 three-wk cycles. Randomization (R) stratification: histology (squamous [sq] vs non-sq). Primary endpoint: major pathological response rate at time of surgery.CANOPY-A (NCT03447769), CANOPY-1 (NCT03631199), and CANOPY-2 (NCT03626545) are ph 3, multicenter, double-blind studies. In CANOPY-A (Cana in adjuvant setting), pts (~1500) with stages IIA-IIIA and IIIB (T&gt;5 cm N2), any histology, completely resected (R0) NSCLC post cisplatin-based chemotherapy (CTx) and radiation therapy (if applicable) are randomized 1:1 to Cana (200 mg SC Q3W)/placebo (PBO; SC Q3W) for 18 cycles. R stratification: AJCC/UICC v.8 stage (IIA vs IIB vs IIIA vs IIIB with T&gt;5 cm, N2 disease), histology (sq vs non-sq), region (western Europe and North America vs eastern Asia vs rest of the world). Primary endpoint: disease-free survival. CANOPY-1 and CANOPY-2 consist of Part 1 (open-label, safety run-in; enrollment complete) and Part 2 (randomized 1:1, PBO-controlled, efficacy & safety; ongoing). CANOPY-1 eligibility: pts with previously untreated stages IIIB/IIIC or IV NSCLC and known PD-L1 status (for Part 2), without EGFR sensitizing mutations and/or ALK rearrangements. Part 1 (3 cohorts of ~9 pts each, based on different platinum-CTx): to confirm the recommended phase 3 regimen (RP3R) for Cana. In Part 2, pts (~600) are randomized to Cana (200 mg SC Q3W)/PBO + pembro + CTx for 4 cycles, followed by maintenance tx (Cana/PBO + pembro ± pemetrexed) until progressive disease (PD). R stratification: PD-L1 status (tumor proportion score &lt;1% vs ≥1%), histology (sq vs non-sq), geographic region (eastern Asia vs North America + western Europe vs rest of the world). Screening has ceased as of Dec 9, 2019. In CANOPY-2, pts with stage IIIB-IV NSCLC, who received prior PD-(L)1 inhibitor therapy and platinum-based CTx, without EGFR sensitizing mutations and/or ALK rearrangements are eligible. Part 1 (~9 pts): to confirm the RP3R of Cana + docetaxel. In Part 2, pts (~226) are randomized to receive Cana (200 mg SC Q3W)/PBO + docetaxel (75 mg/m2 iv Q3W) until PD. R stratification: number of prior lines of therapy in advanced setting (1 vs 2 prior lines of therapy) and histology (sq vs non-sq). Primary endpoints: CANOPY-1 and CANOPY-2 Part 1: to confirm RP3R of the combination; CANOPY-1 Part 2: progression-free survival and overall survival (OS); CANOPY-2 Part 2: OS.

Citation Format: Luis Paz-Ares, Edward B. Garon, Tony Mok, Andrea Ardizzoni, Fabrice Barlesi, Byoung Chul Cho, Gilberto de Castro, Pedro De Marchi, Enriqueta Felip, Yasushi Goto, Alastair Greystoke, Shun Lu, Darren Wan-Teck Lim, Martin Reck, Benjamin J. Solomon, David R. Spigel, Daniel SW Tan, Michael Thomas, James Chih-Hsin Yang, Jay M. Lee, Pilar Garrido, Edward Kim, Bruce E. Johnson. CANOPY program clinical trials: Canakinumab (Cana) in patients (pts) with non-small cell lung cancer (NSCLC) [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT286.

Abstract CT025: Impact of the EML4-ALK fusion variant on the efficacy of lorlatinib in patients (pts) with ALK-positive advanced non-small cell lung cancer (NSCLC)

BACKGROUND: Lorlatinib is a selective, potent, brain-penetrant, 3rd-generation (gen) ALK/ROS1 tyrosine kinase inhibitor (TKI) preclinically active against most known ALK resistance mutations. In pts with ALK+ advanced NSCLC with disease progression following 2nd-gen ALK TKIs, lorlatinib has shown robust clinical activity and we found that tumor genotyping for ALK mutations may identify such pts more likely to respond to lorlatinib treatment. Prior analyses have suggested that EML4-ALK variant type may influence ALK TKI treatment benefit. To further identify molecular correlates of response, we performed an exploratory subgroup analysis by EML4-ALK variant type and ALK resistance mutations in pts previously treated with 2nd-gen ALK TKIs and who received the recommended Ph 2 dose of lorlatinib (100 mg once daily). METHODS: Baseline plasma samples were collected from pts with ALK+ NSCLC with ≥1 prior 2nd-gen ALK TKI enrolled in the ongoing registrational Ph 2 study (NCT01970865). Circulating free DNA (cfDNA) was analyzed using Guardant360 (Guardant Health, Inc., CA, USA) to determine EML4-ALK variant and ALK kinase domain mutations. Objective response rate (ORR) and duration of response (DOR), by independent central review, were evaluated according to EML4-ALK variant type and ALK resistance mutation status. RESULTS: ALK fusions were detectable in 64 (41.0%) of 156 pt plasma samples. EML4-ALK variants 1, 2, and 3 were detected at frequency of 17.3%, 2.6% and 15.4%, respectively. Other EML4-ALK variants (including the variant types 4, 5, 7, and 8) were also detected in 3.2% of pts, as well as some other less frequent fusion partners (e.g., KIF5B) in 2.6% of pts. Based on cfDNA, ALK resistance mutations were detected in 40 pts; of whom, 6 pts harbored EML4-ALK variant 1, 1 pt had variant 2 and 18 had variant 3. The G1202R/Del mutation was detected in 23 pts samples; of which, 15 (65.2%) also harbored EML4-ALK variant 3. ORR was 33.3% (95% CI 16.5-54.0), 75.0% (95% CI 19.4-99.4) and 45.8% (95% CI 25.6-67.2) for variants 1, 2 and 3, respectively, while median DOR was similar for pts with variant 1 or 3 (both 6.9 months). Median DOR was not reached for variant 2. Of note, no responses were observed in the pts with other types of ALK rearrangements detected. Finally, ALK fusions were not detected in the cfDNA of 92 pts (59.0%), including 12 pts who had detectable ALK mutations. Among these 92 pts, ORR was 39.1% (95% CI 29.1-49.9) and median DOR was 7.1 months (95% C 5.5-not reached). Confirmation of these results in the tumor tissue is ongoing. CONCLUSION: In this heavily pretreated group of ALK+ NSCLC pts, the presence of an ALK resistance mutation might enrich for EML4-ALK variants 1 and 3. Lorlatinib exhibited antitumor activity irrespective of EML4-ALK variant and across a variety of ALK resistance mutations.

Citation Format: Todd M. Bauer, Jean-François Martini, Benjamin Besse, Chia-Chi Lin, Ross A. Soo, Gregory J. Riely, Sai-Hong Ignatius Ou, Francesca Toffalorio, Antonello Abbattista, Holger Thurm, D. Ross Camidge, Steven Kao, Rita Chiari, Shirish Gadgeel, Enriqueta Felip, Alice T. Shaw, Benjamin J. Solomon. Impact of the EML4-ALK fusion variant on the efficacy of lorlatinib in patients (pts) with ALK-positive advanced non-small cell lung cancer (NSCLC) [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT025.

IL-15 Preconditioning Augments CAR T Cell Responses to Checkpoint Blockade for Improved Treatment of Solid Tumors

Chimeric antigen receptor (CAR) T cell therapy has been highly successful in hematological malignancies leading to their US Food and Drug Administration (FDA) approval. However, the efficacy of CAR T cells in solid tumors is limited by tumor-induced immunosuppression, leading to the development of combination approaches, such as adjuvant programmed cell death 1 (PD-1) blockade. Current FDA-approved methods for generating CAR T cells utilize either anti-CD3 and interleukin (IL)-2 or anti-CD3/CD28 beads, which can generate a T cell product with an effector/exhausted phenotype. Whereas different cytokine preconditioning milieu, such as IL-7/IL-15, have been shown to promote T cell engraftment, the impact of this approach on CAR T cell responses to adjuvant immune-checkpoint blockade has not been assessed. In the current study, we reveal that the preconditioning of CAR T cells with IL-7/IL-15 increased CAR T cell responses to anti-PD-1 adjuvant therapy. This was associated with the emergence of an intratumoral CD8⁺CD62L⁺TCF7⁺IRF4^- population that was highly responsive to anti-PD-1 therapy and mediated the vast majority of transcriptional and epigenetic changes in vivo following PD-1 blockade. Our data indicate that preservation of CAR T cells in a TCF7⁺ phenotype is crucial for their responsiveness to adjuvant immunotherapy approaches and should be a key consideration when designing clinical protocols.

Real world outcomes in KRAS G12C mutation positive non-small cell lung cancer

BACKGROUND

KRAS mutations are found in 20-30 % of non-small cell lung cancers (NSCLC) and were traditionally considered undruggable. KRAS^G12C mutation confers sensitivity to KRAS^G12C covalent inhibitors, however its prognostic impact remains unclear. This study assesses the frequency, clinical features, prevalence of brain metastases and outcomes in KRAS^G12C NSCLC in a real-world setting.

METHODS

Patients enrolled in the prospective Thoracic Malignancies Cohort (TMC) between July 2012 to October 2019 with recurrent/metastatic non-squamous NSCLC, available KRAS results, and without EGFR/ALK/ROS1 gene aberrations, were selected. Data was extracted from TMC and patient records. Clinicopathologic features, treatment and overall survival (OS) was compared for KRAS wildtype (KRAS^WT) and KRAS mutated (KRAS^mut); and KRAS^G12C and other (KRAS^other) mutations.

RESULTS

Of 1386 NSCLC patients, 1040 were excluded: non-metastatic/recurrent (526); unknown KRAS status (356); ALK/EGFR/ROS1 positive (154); duplicate (4). Of 346 patients analysed, 144 (42 %) were KRAS^mut, of whom 65 (45 %) were KRAS^G12C. All patients with KRAS^G12C were active or ex-smokers, compared to 92 % of KRAS^other and 83 % of KRAS^WT. The prevalence of brain metastases during follow-up was similar between KRAS^mut and KRAS^WT (33 % vs 40 %, p = 0.17), and KRAS^G12C and KRAS^other (40 % vs 41 %, p = 0.74). The proportion of patients receiving one or multiple lines of systemic therapy was comparable. OS was similar between KRAS^mut and KRAS^WT (p = 0.54), and KRAS^G12C and KRAS^other (p = 0.39).

CONCLUSION

Patients with KRAS^mut and KRAS^WT, and KRAS^G12C and KRAS^other NSCLC have comparable clinical features, treatment and survival. While not prognostic, KRAS^G12C may be an important predictive biomarker as promising KRAS^G12C covalent inhibitors continue to be developed.

Targeting platelets for improved outcome in KRAS-driven lung adenocarcinoma

Elevated platelet count is associated with poor survival in certain solid cancers, including lung cancer. In addition, experimental transplantation of cancer cell lines has uncovered a role for platelets in blood-borne metastasis. These studies, however, do not account for heterogeneity between lung cancer subtypes. Subsequently, the role of platelets in the major subtypes of non-small cell lung cancer (adenocarcinoma (ADC) and squamous cell carcinoma (SqCC)) is not fully understood. We utilised an autochthonous Kras^LSL-G12D/+;p53^flox/flox mouse model of lung ADC together with genetic models of thrombocytopenia to interrogate the role of platelets in lung cancer growth and progression. While thrombocytopenia failed to impact primary tumour growth, in experimental metastatic models however, thrombocytopenic mice displayed significantly extended survival. Utilising a novel thrombocytopenic immunocompromised mouse, the importance of platelets in metastatic dissemination was confirmed with human KRAS-mutant ADC cell lines. Finally, retrospective analysis of a NSCLC patient cohort revealed thrombocytosis was predictive of poor survival in ADC patients with metastatic disease. Interestingly, this association was not apparent in SqCC patients. Overall, these data highlight the possibility of patient stratification using thrombocytosis as a biomarker, and indicates opportunities for potential novel treatment strategies that combine anti-platelet and lung cancer therapies.

TP53 Status, Patient Sex, and the Immune Response as Determinants of Lung Cancer Patient Survival

Lung cancer poses the greatest cancer-related death risk and males have poorer outcomes than females, for unknown reasons. Patient sex is not a biological variable considered in lung cancer standard of care. Correlating patient genetics with outcomes is predicted to open avenues for improved management. Using a bioinformatics approach across non-small cell lung cancer (NSCLC) subtypes, we identified where patient sex, mutation of the major tumor suppressor gene, Tumour protein P53 (TP53), and immune signatures stratified outcomes in lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC), among datasets of The Cancer Genome Atlas (TCGA). We exposed sex and TP53 gene mutations as prognostic for LUAD survival. Longest survival in LUAD occurred among females with wild-type (wt) TP53 genes, high levels of immune infiltration and enrichment for pathway signatures of Interferon Gamma (INF-γ), Tumour Necrosis Factor (TNF) and macrophages-monocytes. In contrast, poor survival in men with LUAD and wt TP53 genes corresponded with enrichment of Transforming Growth Factor Beta 1 (TGFB1, hereafter TGF-β) and wound healing signatures. In LUAD with wt TP53 genes, elevated gene expression of immune checkpoint CD274 (hereafter: PD-L1) and also protein 53 (p53) negative-regulators of the Mouse Double Minute (MDM)-family predict novel avenues for combined immunotherapies. LUSC is dominated by male smokers with TP53 gene mutations, while a minor population of TCGA LC patients with wt TP53 genes unexpectedly had the poorest survival, suggestive of a separate etiology. We conclude that advanced approaches to LUAD and LUSC therapy lie in the consideration of patient sex, TP53 gene mutation status and immune signatures.

Assessing real-world outcomes in metastatic colorectal cancer with KRASG12C mutation

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Background: The KRASG12C mutation is present in 3% of colorectal cancer and is of particular interest given the recent development of specific targeting drugs. Previous data suggest KRAS (all) mutations may impact prognosis. Here we assess the clinical features and outcomes of real world patients with KRASG12C mutant metastatic colorectal cancer (mCRC) to explore any clinicopathologic associations and prognostic impact. Methods: Patients diagnosed with mCRC between January 2011 and December 2018 were included in this prospective mCRC registry. Patients with BRAF mutations, unknown or unspecified KRAS variants were excluded. Clinicopathologic features, treatment and overall survival (OS) were compared for RAS wildtype (RASWT) and KRASG12C mutant patients, and between KRASG12C and other (RASother) mutations. Results: Of 1308 patients analysed, 674 (52%) were RASmut, of whom 56 (8.3%) were KRASG12C. More patients with KRASG12C were female compared to RASother and RASWT (Table). No differences were observed in primary tumor location, number of metastatic sites and distribution of metastases. The proportion of patients undergoing metastasectomy was similar between KRASG12C and RASother, and KRASG12C and RASWT. There was no difference in the proportion of patients receiving systemic therapy. RASWT patients received more lines of therapy. Median OS was similar between KRASG12C, RASother, and RASWT: 31.7 vs 29.2 vs 31.8 months respectively (P = 0.545). Conclusions: KRASG12C mutations were observed in 4.3% of mCRC patients and in 8.3% of RAS mutant cases. Patients with KRASG12C have comparable clinical features to RASWT or RASother mCRC. Treatment and survival were also similar between groups. KRASG12C does not appear to be prognostic, but may be an important predictive biomarker as promising targeted therapies continue to be developed. [Table: see text]

Correlation between overall response rate and progression-free survival/overall survival in comparative trials involving targeted therapies in molecularly enriched populations

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Background: Randomized trials involving agents targeting oncogene addicted tumors have greatly increased over the past decade. Whether clinical response rates can predict or correlate with efficacy measures such as progression-free survival (PFS) or overall survival (OS) has not been established in molecularly enriched patient populations. In this meta-analysis, we investigated whether improvements in objective response rate (ORR) in comparative trials using targeted agents could serve as a potential surrogate endpoint for improvements in PFS or OS in populations with oncogene addicted cancer. Methods: CT.gov and MEDLINE databases were queried (using commercial text mining software I2E) for randomized, phase 3 clinical trials based on the following prospectively defined criteria: (1) use of agents targeting EGFR activating mutations (erlotinib, gefitinib, afatinib, dacomitinib, osimertinib), ALK and ROS1 rearrangements (crizotinib, ceritinib, alectinib), BRAF V600E or V600K mutations (dabrafenib), and BCR-ABL fusion protein (imatinib, dasatinib, nilotinib, ponatinib); (2) must include molecularly enriched trial populations (biomarker subgroup data included if available); (3) control arms should not include targeted agents directed towards those molecularly enriched populations. ORR, OS, and PFS data were manually extracted from the relevant studies and correlative analyses (weighted Pearson correlation) were performed. Results: 61 trials were identified with 15 ultimately meeting the prespecified criteria. ORR effect size (both the ORR difference and log odds ratio) and the log PFS hazard ratio were strongly correlated (-0.78, p-value = 0.0007). No significant correlation was found between ORR and OS. Conclusions: In our analyses, a strong correlation between ORR and PFS was found in randomized clinical trials investigating agents targeting oncogene-driven cancers. Establishing a correlation between ORR and OS was limited, most probably due to confounding factors such as treatment cross-over following progression, number of subsequent therapies and long post-progression survival in this setting. These findings further warrant the use of ORR as a surrogate for PFS in biomarker-driven studies.

Assessing the significance of KRAS G12C mutation: Clinicopathologic features, treatments, and survival outcomes in a real-world KRAS mutant non-small cell lung cancer cohort

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Background: KRASG12C mutations are present in 15% of non-small cell lung cancer (NSCLC) and have recently been shown to confer sensitivity to KRAS(G12C) inhibitors. This study aims to assess the clinical features and outcomes with KRASG12C mutant NSCLC in a real-world setting. Methods: Patients enrolled in an Australian prospective cohort study, Thoracic Malignancies Cohort (TMC), between July 2012 to October 2019 with metastatic or recurrent non-squamous NSCLC, with available KRAS test results, and without EGFR, ALK, or ROS1 gene aberrations, were selected. Data was extracted from TMC and patient records. Clinicopathologic features, treatment and overall survival was compared for KRAS wildtype ( KRASWT) and KRAS mutated ( KRASmut) patients, and between KRAS G12C ( KRASG12C) and other ( KRASother) mutations. Results: Of 1386 patients with non squamous NSCLC, 1040 were excluded for: non metastatic or recurrent (526); KRAS not tested (356); ALK, EGFR or ROS1 positive (154); duplicate (4). Of 346 patients analysed, 202 (58%) were KRASWT and 144 (42%) were KRASmut, of whom 65 (45%) were KRASG12C. 100% of pts with KRASG12C were smokers, compared to 92% of KRASother and 83% of KRASWT. The prevalence of brain metastases over entire follow-up period was similar between KRASmut and KRASWT (33% vs 40%, p = 0.17), and KRASG12C and KRASother (40% vs 41%, p = 0.74). Likewise, there was no difference in the proportion of patients receiving one or multiple lines of systemic therapy. Overall survival (OS) was also similar between KRASmut and KRASWT (p = 0.54), and KRASG12C and KRASother (p = 0.39). Conclusions: In this real-world prospective cohort, patients had comparable clinical features regardless of having a KRASmut, KRASG12C or KRASother mutation, or being KRASWT . Treatment and survival were also similar between groups. While not prognostic, KRASG12C may be an important predictive biomarker as promising KRAS G12C covalent inhibitors continue to be developed.

Selpercatinib (LOXO-292) in patients with RET-mutant medullary thyroid cancer

3594

Background: Selpercatinib (LOXO-292) is a highly selective and potent small molecule RET kinase inhibitor. Here we report an update on the efficacy and safety of selpercatinib in RET-mutant medullary thyroid cancer (MTC). Methods: Patients with RET-mutant MTC were enrolled to the Phase 1/2 LIBRETTO-001 trial (NCT03157128), a global, multicenter trial (16 countries, 89 sites). Following the Phase 1 dose escalation portion of the trial, patients received the recommended dose of 160 mg orally twice daily. Each cycle was 28 days. The primary endpoint was objective response rate (ORR) per RECIST 1.1. Secondary endpoints included duration of response (DoR) and safety. Per health authority agreement, the primary analysis set was defined as the first 55 consecutively enrolled patients previously treated with multikinase inhibitors cabozantinib and/or vandetanib. Patients naïve to cabozantinib and vandetanib treatment were analyzed separately. All analyses were based on a 16-Dec-2019 data cutoff date. Results: In the primary analysis set of prior cabozantinib and/or vandetanib-treated patients with MTC (n = 55), the ORR by investigator assessment was 62% (95% CI 47.7–74.6, n = 34/55) and the median DoR was not reached (95% CI 18.4 months–not estimable) despite a median follow-up of 14.8 months. In cabozantinib/vandetanib treatment-naïve patients (n = 88), the ORR by investigator assessment was 69% (95% CI 58.6–78.7, n = 61/88, including 2 responses pending confirmation). Of the 59 confirmed responding patients, with a median follow-up of 8 months, responses were ongoing for 57 responders at the time of the analysis. In the safety analysis set consisting of all selpercatinib dosed patients (N = 702), the most common treatment-related adverse events (TRAEs) that occurred in ≥15% of patients were dry mouth (33.3%), increased AST (24.5%), increased ALT (23.8%), hypertension (23.2%), diarrhea (19.7%), and fatigue (16.8%). Only 2% (14 of 702) of patients discontinued selpercatinib for TRAEs. Conclusions: Selpercatinib use was associated with marked and durable antitumor activity in prior cabozantinib and/or vandetanib-treated patients and in cabozantinib/vandetanib-naïve patients with RET-mutant MTC, with the majority of responses ongoing in both cohorts. Selpercatinib was well tolerated. Efficacy data assessed by independent review committee based on the 16-Dec-2019 data cutoff date will be presented. Clinical trial information: NCT03157128 .