Rationale and Design of the Phase 3 KEYLYNK-013 Study of Pembrolizumab With Concurrent Chemoradiotherapy Followed by Pembrolizumab With or Without Olaparib for Limited-Stage Small-Cell Lung Cancer

BACKGROUND

The current standard of care for patients with newly diagnosed limited-stage small-cell lung cancer (SCLC) is concurrent chemoradiotherapy (CCRT). The prognosis remains poor due to the aggressiveness and high risk of progression or relapse of SCLC even if an initial response is achieved. Therefore, there is an urgent unmet clinical need in this population. The multicenter, phase 3, randomized, placebo-controlled, double-blind KEYLYNK-013 study evaluates the addition of pembrolizumab to CCRT followed by pembrolizumab with or without olaparib in participants with previously untreated limited-stage SCLC. (ClinicalTrials.gov: NCT04624204).

METHODS

Eligible participants aged ≥18 years with newly diagnosed, pathologically confirmed, limited-stage (ie, stage I-III) SCLC will be randomized 1:1:1 to CCRT (ie, etoposide plus carboplatin or cisplatin for 4 cycles and standard thoracic radiotherapy) plus pembrolizumab (Groups A and B) or CCRT plus placebo (Group C). In the absence of disease progression, participants will receive pembrolizumab plus placebo (Group A), pembrolizumab plus olaparib (Group B), or placebo (Group C). Dual primary endpoints are progression-free survival per RECIST version 1.1 by blinded independent central review and overall survival.

RESULTS

Enrollment began in December 2020 and is ongoing at approximately 150 sites.

CONCLUSIONS

KEYLYNK-013 will provide valuable information on the efficacy and safety of pembrolizumab plus CCRT and pembrolizumab with or without olaparib post CCRT in participants with limited-stage SCLC.

Phase I study of entinostat (Ent), atezolizumab (A), carboplatin (C), and etoposide (E) in previously untreated extensive-stage small cell lung cancer (ES-SCLC), ETCTN 10399

e20606

Background: A-CE has demonstrated improved overall survival in ES-SCLC, but there are currently no approved therapies targeting genomic alterations in SCLC. Mutations in acetyltransferases CREBBP and EP300 occur at a frequency of 15% and 13%, respectively, in SCLC, and PDX models with CREBBP mutations were demonstrated to be susceptible to targeting with HDAC inhibitors. Ent, a class I selective HDAC inhibitor, has also demonstrated clinical activity in a combination with pembrolizumab in patients with NSCLC and uveal melanoma with minimal hematologic toxicity at RP2D of 5 mg PO weekly. We conducted a phase I trial to evaluate the combination of Ent with A-CE for ES-SCLC, NCI ETCTN 10399. Methods: Patients (pts) with treatment-naïve ES-SCLC, stable or treated brain metastases, ECOG ≤2 were enrolled and treated on up to 4 dose levels of Ent. Allocation to cohorts was determined using Bayesian optimal interval (BOIN) design targeting a MTD with a DLT rate of 20%. Dose levels (DL) included Ent 2 mg, 3 mg, or 5 mg PO weekly on day (d) 1 in addition to 4 cycles of A-CE (A 1200 mg, C AUC 5, E 100 mg/m2 d 1-3) followed E+A for 1 year. Pre-treatment tissue and plasma collected for WES. Results: 3 pts were enrolled and treated at DL1 with Ent 2 mg. Pts were age 69-83, 2 male, 1 female, 2 were ECOG 1, 1 was ECOG 0, and 1 with prior SRS radiation for brain metastases. 2 of 3 experienced DLTs during cycle 1: (1) Grade (Gr) 4 febrile neutropenia after 2 doses of Ent and (1) Gr 5 sepsis after 1 dose of Ent. BOIN design required stopping accrual to dose level 1 and the trial was closed to further accrual. The pt without DLT experienced grade 3 thrombocytopenia after 2 doses of Ent, but recovered after holding cycle 1, day 15 Ent. This patient experienced Gr 3 neutropenia during cycle 2. The most common adverse events were anemia (3), neutropenia (3), thrombocytopenia (2), leukopenia (2), hypocalcemia (2). Of these, most were Gr 3-4: anemia (1), neutropenia (3), thrombocytopenia (2), leukopenia (1), hypocalcemia (1). Conclusions: The combination of low dose Ent 2 mg PO weekly + AC-E is unsafe and resulted in early onset and severe neutropenia, thrombocytopenia in the first 1-2 weeks and ≥Gr 3 neutropenia and thrombocytopenia prior to completing 2 cycles of treatment for all pts. There is no role for further exploration of entinostat with carboplatin, etoposide, and atezolizumab. Clinical trial information: NCT04631029.

Early ctDNA response assessment for prediction of platinum sensitivity in small cell lung cancer

9067

Background: Small cell lung cancer (SCLC) is an aggressive disease, characterized by inevitable chemotherapy resistance and rapid progression. We hypothesized that circulating tumor DNA (ctDNA) analysis can rapidly identify sensitivity to platinum-based therapy. Methods: Patients with SCLC at Memorial Sloan Kettering Cancer Center underwent serial plasma collections, including prior to the start of treatment and prior to Cycle 2 Day 1 of therapy (C2D1). Tumor mutations were identified from pre-treatment biopsies by MSK-IMPACT and/or pre-treatment plasma by CAncer Personalized Profiling by deep Sequencing (CAPP-Seq). Median variant allele fraction (VAF) of all mutations was monitored on subsequent blood draws using CAPP-Seq. Progression free survival (PFS) was measured from the time of first pre-treatment blood draw. Results: Plasma was collected from 19 patients treated with carboplatin and etoposide, including three who received concurrent atezolizumab. Seven were female, and mean age was 64.5 years. ctDNA was detected in 17 patients (89%), including in the two patients in our series with limited stage disease. The most common mutations were in TP53 and RB1 in 14 and 6 patients, respectively. Fourteen patients had available plasma at C2D1. At baseline prior to treatment, median VAF did not differ significantly between radiologic responders and non-responders (9.4% versus 30.3%, p = 0.35). After one cycle of chemotherapy, the VAF percent decrease was significantly more in responders versus non-responders (-96.9% versus -10.3%, p < 0.001). Median VAF was therefore significantly lower by C2D1 in patients who responded compared to non-responders (0.51% versus 27.2%, p = 0.02). Those who ultimately responded to therapy all had a > 2 fold decrease in VAF by C2D1. With a median follow-up of 180 days, PFS was significantly longer in patients with > 2 fold decrease in VAF by C2D1 (6.4 versus 1.9 months, log rank p < 0.001). Conclusions: A 2-fold decrease in plasma VAF by C2D1 predicted platinum-sensitivity in SCLC and was associated with longer PFS. ctDNA may permit early assessment of benefit and expedite alternative treatment options for those without significant decrease in median VAF after one cycle of therapy.

Molecular subtypes and clinical outcomes to initial systemic treatment in patients with small cell lung cancer

9018

Background: Investigators have proposed that differential expression of the transcription regulators ASCL1 and NeuroD1 can be used to define molecular subtypes of small cell lung cancers (SCLCs). Here we evaluate SCLC subtypes based on ASCL1 and NeuroD1 expression in patients (pts) treated with first-line (1L) chemotherapy profiled with targeted next-generation sequencing (NGS). Methods: We used NGS (MSK-IMPACT) to profile tumors from pts with SCLCs. We performed IHC to assess ASCL1 (A) or NeuroD1 (N). Objective response rate (ORR) to therapy was determined using RECIST. PFS and OS were analyzed using Kaplan-Meier. Results: 281 pts with SCLCs were profiled with NGS (102 LS-SCLC; 179 ES-SCLC). Most frequently mutated genes were TP53 (90%), RB1 (68%), KMT2D (22%), NOTCH1 (15%), FAT1 (14%), PTPRD (12%). Mutations in BIRC3, FOXL2, TENT5C, TET1, NRAS, KIT, TSHR, ESR1 were enriched in ASCL1-/NeuroD1+ (A-/N+), and mutations in KMT2D and EP300 were enriched in A-/N- (p<0.05). Copy number alterations in WWTR1, ATR, IKZF1, PALB2, PIK3CB were enriched in A-/N+ (p<0.05). IHC for ASCL1 and NeuroD1 was performed on 78 samples: 11 A-/N-, 32 A+/N-, 4 A-/N+, 31 A+/N+. Overall survival at 1 year based on subtype was 25% in A-/N- (2/9), 60% in A-/N+ or A+/N- (13/32), and 55% in A+/N+ (10/25). For the 10 pts who survived 2 years, 5 were A+/N- and 5 were A+/N+. 146 pts treated with 1L platinum had RECIST-evaluable disease. ORR was 75% (110/146; 95% CI 68-82%). Median PFS was 7 months with CR/PR and 3.5 months with SD/PD (HR 0.32; 95% CI 0.18-0.56). Median OS was 17 months with CR/PR and 11 months with SD/PD (HR 0.55; 95% CI 0.34-0.9). Mutations in RUNX1, EPHA7, CDKN2A, FLT1 and copy number alterations in FGFR1, CCND1 were enriched in patients with SD/PD (p<0.05). PFS rate at 6 months was 25% in A-N- (1/4), 60% in A-/N+ or A+/N- (9/15), and 55% in A+/N+ (6/11). For the 7 pts who survived 2 years, 3 were A+/N- and 4 were A+/N+. Conclusions: Molecular subtypes defined by ASCL1 and NeuroD1 encompass molecular characteristics that may predict patient outcomes. Further investigation is needed to delineate the underlying biological differences among the various subtypes to help define therapeutic vulnerabilities of each subtype of SCLC. Completion of IHC for ASCL1, NeuroD1 and additional key transcription factors POU2F3 and YAP1 are in progress for the entire cohort. WES and RNA sequencing are occurring in parallel and will be correlated with IHC results and clinical outcomes.

Phase I study of AMG 757, a half-life extended bispecific T-cell engager (HLE BiTE immune therapy) targeting DLL3, in patients with small cell lung cancer (SCLC)

TPS9080

Background: SCLC is an aggressive neuroendocrine tumor with poor prognosis and few treatment options. Delta-like ligand 3 (DLL3) is an inhibitory Notch ligand that is highly expressed on the surface of most SCLC tumors but minimally expressed in normal tissues. As such, DLL3 may be a promising therapeutic target. AMG 757 is an HLE BiTE immune therapy designed to redirect cytotoxic T cells to cancer cells by binding to DLL3 on cancer cells and CD3 on T cells, resulting in T cell activation and expansion and T cell-dependent killing of tumor cells. In addition to its direct antitumor effect, BiTE immune therapy can inflame the tumor microenvironment. Combining AMG 757 with a PD-1 pathway inhibitor may lead to increased antitumor activity by enabling sustained T cell-dependent killing of tumor cells. Methods: NCT03319940 is an open-label, ascending, multiple-dose, phase 1 study evaluating AMG 757 as monotherapy; the protocol was recently amended to also evaluate AMG 757 in combination with pembrolizumab. The study will include a dose exploration (monotherapy and combination) followed by a dose expansion (monotherapy). Key eligibility criteria: adult patients with relapsed/refractory SCLC whose disease progressed or recurred after at least 1 platinum-based chemotherapy regimen, ECOG performance status 0–2, at least 2 measurable lesions per modified RECIST 1.1, no untreated or symptomatic brain metastases, and adequate organ function. Primary objectives are to evaluate safety/tolerability and determine the maximum tolerated dose or recommended phase 2 dose of AMG 757 as monotherapy and in combination with pembrolizumab. Secondary objectives are to characterize pharmacokinetics and evaluate preliminary antitumor activity; exploratory objectives are to assess immunogenicity and changes in biomarkers in blood and tumor tissue. In the dose exploration phase, dose escalation/de-escalation decisions will be guided by a Bayesian logistic regression model; backfill enrollment at dose levels deemed safe and tolerable will be allowed. The study is open and recruiting patients. Clinical trial information: NCT03319940.

Real-world experience and molecular features of response to immune checkpoint blockade in patients with recurrent small cell lung cancer

8556

Background: Immune checkpoint blockade (ICB) is now a routine component of treatment in recurrent small cell lung cancer (SCLC). We evaluated the response to ICB in patients (pts) with recurrent SCLC and genomic features of response using next-generation sequencing (NGS). Methods: Pts with recurrent SCLC treated with ICB were identified. The majority of pts were treated outside of a clinical trial to focus emphasis on the real-world experience. Tumor mutation burden (TMB) and the landscape of somatic variants were determined by targeted NGS using MSK-IMPACT. Objective response rate (ORR) to ICB was determined using RECIST v1.1. PFS and OS were measured from the start of ICB and analyzed using Kaplan-Meier. Results: Between December 2013 and October 2018, 108 pts with SCLC were treated with ICB (57 subjected to NGS). Pts received PD-1 monotherapy alone (n = 28) or in combination with CTLA-4 blockade (n = 80). Median line of therapy was 2 (range 1-6). ORR was 14% (15/108, 95% CI 8-22%). From the start of ICB, median PFS was 1.4 months in non-responders and 10.8 months in responders (HR 0.2; 95% CI 0.13-0.32). Median OS was 6.3 months in non-responders and undefined in responders (range 8-44 months) (HR 0.26, 95% CI 0.16-0.44). Four responders remain on ICB treatment. TMB in the ICB-treated cohort was similar to that of an unselected cohort (n = 233) of SCLC (median 8.8 Mt/MB vs 8.2 Mt/MB, p = 0.71). Clinical benefit was enriched among those with a higher TMB (upper vs middle/lower tertile PFS HR 0.48, 95% CI 0.28-0.84, p = 0.01 and ORR 26% [5/19] vs ORR 8% [3/38]). Rates of whole genome duplication and commonly altered genes in SCLC ( TP53, RB1, KMT2C/D, NOTCH1/2/4, PTPRD, APC) were similarly distributed across responders and non-responders. Completion of whole-exome sequencing and PD-L1 testing is in progress. Conclusions: In pts with recurrent SCLC receiving routine clinical care, the ORR to ICB is comparable to reports from clinical trials. A high TMB was associated with a longer median PFS and better response. Further investigation into the genomic landscape of recurrent SCLC is needed to identify biomarkers predictive of response to ICB.

Lung cancers with mutations in EGFR exon 18: Molecular characterization and clinical outcomes in response to tyrosine kinase inhibitors

9029

Background: Little data is available to guide clinical management of individuals with less common oncogenic drivers such as exon 18 mutations (ex18m) in EGFR. To better understand the impact of these rare mutations on treatment outcomes, we reviewed clinicopathologic data in patients (pts) with ex18m treated with tyrosine kinase inhibitors (TKI) in EGFR-mutant lung cancers. Methods: Pts with EGFR ex18m were detected via molecular diagnostics using Sequenom™, FoundationOne™ or MSK IMPACT™ NGS testing from 2003-2016. We reviewed their clinical data for molecular alterations in EGFR, treatment outcomes in response to TKI (time on treatment) and median overall survival (OS). Results: We identified mutations in EGFR ex18m in 63 pts. Median age at diagnosis was 68; 63% were women; 29% never smokers. Overall, 74 ex18m were found in 63 pts, including: G719A = 38, G719S = 11, G719C = 8, E709K = 6, E709_T710delinsD = 6, E709A = 3, G719D = 2. E709 and G719 co-mutations in ex18 were found in 9 pts, and 1 pt was found to have 3 separate tumors, each with a distinct ex18m. 29/63 (46%) patients with ex18m had a co-occurring EGFR mutation: 9 with another ex18m; 20 with ex19-21m. Using our IMPACT NGS, the median number of co-mutations was 8 (range 1-17). Two out of 63 pts had a pre-treatment T790M mutation. The 25 pts with non-metastatic disease presented in the following stages: IA = 19; IB = 3; IIB = 1; IIIA = 2; IIIB = 2. 34/38 pts with metastatic disease were treated with the following first-line EGFR-TKIs: erlotinib = 28, afatinib = 5, osimertinib = 1. Median duration on TKI treatment in months was: erlotinib = 10 mo, (range 1-25), afatinib = 3 mo (range 2-9), osimertinib = 4 mo. Median OS from the date of diagnosis of metastatic disease was 22 months (95% CI 18-29). In comparison, a similar cohort of pts with sensitizing EGFR exon19del/L858R mutations had a median OS of 31 months (95% CI 28-33) (Naidoo Cancer2015). Conclusions: Almost half of ex18m occur concurrently with another EGFR mutation. Overall, ex18m pts have a shorter median OS when compared to similar patient cohorts. EGFR-TKIs appear to be an effective treatment for pts with ex18m in EGFR-mutant lung cancers.

Afatinib in patients with metastatic HER2-mutant lung cancers: An international multicenter study

9071

Background: Human epidermal growth factor 2 ( HER2, ERBB2) mutations have been identified as oncogenic drivers in 3% of lung cancers. Afatinib is an irreversible tyrosine kinase inhibitor of HER1 (EGFR), HER2 and HER4 and has been described in case reports to have activity in HER2-mutant lung cancers. However, there is little data to inform the clinical use of afatinib. Methods: We reviewed patients with metastatic HER2-mutant lung cancers treated with afatinib among 7 institutions between 2009 and 2016. The primary endpoint was investigator assessed overall response rate using RECIST v1.1. Other data collected included types of HER2mutations, duration of afatinib treatment and overall survival. Results: We identified 27 patients with metastatic HER2-mutant lung cancers treated with afatinib. Median age at diagnosis was 63 (range 40 to 84); majority were men (n = 16; 59%) and never-smokers (n = 18; 67%). All tumors were adenocarcinomas, and the majority were Stage IV at initial diagnosis (n = 16; 59%). A 12-base pair (bp) in-frame insertion YVMA in exon 20 (p.A775_G776insYVMA) was present in 16 patients (59%). In addition, there were three 9-bp insertions, two 3-bp insertions and two single bp substitutions (L755F and D769H) in exon 20; two single bp substitutions (S310F) in exon 8; one exon 17 V659E mutation; and one single-nucleotide polymorphism (Ile655Val). Median duration on afatinib was 2 months (range 1 to 27); median line of prior treatment was 3 (range 1 to 6). Eight patients had previously received trastuzumab prior to afatinib and one concurrently with afatinib. Overall response rate was 15% (n = 4; 95% CI 4 to 34%); the four partial responses lasted 5, 5, 6 and 10 months. The 3 longest partial responders had a 12-bp insertion in exon 20 (YVMA); the remaining partial responder had a 9-bp insertion in exon 20. Median overall survival from diagnosis date of metastatic disease was 23 months (95% CI 18 to 62). Conclusions: Afatinib produced partial responses in 15% of patients with metastatic HER2-mutant lung cancers, including insertion YVMA. Our findings confirm the activity of afatinib and provide data supporting a framework for its use in the care of patients with HER2-mutant lung cancers.

PD-L1 expression and response to immunotherapy in patients with MET exon 14-altered non-small cell lung cancers (NSCLC)

8512

Background: MET exon 14 skipping alterations ( METΔ14) are present in 4% of NSCLCs. Response to MET inhibition has been observed in ongoing prospective trials (44% response rate, phase 1 trial of crizotinib; Drilon et al ASCO 2016), however responses to other types or therapy, such as immunotherapy, is unknown. We evaluated the immunophenotype of METΔ14 lung cancers and response to PD-(L)-1-based immunotherapy. Methods: Pts with recurrent/metastatic NSCLC were eligible. METΔ14 was identified by broad hybrid capture-based next-generation sequencing (MSK-IMPACT). PD-L1 expression was determined by immunohistochemistry. Response to immune therapy was evaluated by RECIST v1.1. Results: 63 pts with METΔ14-positive non-small cell lung cancers were identified; 41 (65%) had sufficient tissue for PD-L1 analysis. Patient characteristics: median age 71 years, 58% female, median pack year smoking 5.85 years, histology: 73% (30/41) adenocarcinoma, 20% (8/41) pleomorphic carcinoma, 7% (3/41) squamous cell. Tumor PD-L1 expression was ≥50% in 44% (18/41, 95% CI 30-59%), 1-49% in 17% (7/41, 95% CI 8-32%), and < 1 in 39% (16/41, 95% CI 26-54%). The median age for patients with METΔ14 and PD-L1 positive (≥1%) tumors was 65 years (range 49-87); 60% (15/25) of patients were female; Histology: 72% (18/25) adenocarcinoma, 24% (6/25) sarcomatoid carcinoma, and 4% (1/25) squamous cell carcinoma. Immunotherapy was given to 15 pts: nivolumab (5), pembrolizumab (3), atezolizumab (2), durvalumab (1), and ipilimumab+nivolumab (4). The overall response rate to immunotherapy was 13% (2/15, 95% CI 3-39%). Overall response was 33% (1/3; 95% CI 6-80%) in patients with tumors PD-L1 ≥50%, and 20% (1/5, 95%CI 2-64%) in patients with tumors PD-L1 0%. Time on therapy ranged from 2 weeks to 9.6+ months. Conclusions: A substantial proportion of NSCLCs harboring METΔ14 alterations express PD-L1. Despite frequent PD-L1 expression, responses to immunotherapy were overall uncommon and lower than that observed with targeted therapy for this genomically defined subset of patients with lung cancers. Further exploration of this subset may reveal important mechanisms of immunotherapy resistance in PD-L1 expressing tumors.