Predicting response to neoadjuvant chemotherapy with liquid biopsies and multiparametric MRI in patients with breast cancer

Accurate prediction of response to neoadjuvant chemotherapy (NAC) can help tailor treatment to individual patients' needs. Little is known about the combination of liquid biopsies and computer extracted features from multiparametric magnetic resonance imaging (MRI) for the prediction of NAC response in breast cancer. Here, we report on a prospective study with the aim to explore the predictive potential of this combination in adjunct to standard clinical and pathological information before, during and after NAC. The study was performed in four Dutch hospitals. Patients without metastases treated with NAC underwent 3 T multiparametric MRI scans before, during and after NAC. Liquid biopsies were obtained before every chemotherapy cycle and before surgery. Prediction models were developed using penalized linear regression to forecast residual cancer burden after NAC and evaluated for pathologic complete response (pCR) using leave-one-out-cross-validation (LOOCV). Sixty-one patients were included. Twenty-three patients (38%) achieved pCR. Most prediction models yielded the highest estimated LOOCV area under the curve (AUC) at the post-treatment timepoint. A clinical-only model including tumor grade, nodal status and receptor subtype yielded an estimated LOOCV AUC for pCR of 0.76, which increased to 0.82 by incorporating post-treatment radiological MRI assessment (i.e., the "clinical-radiological" model). The estimated LOOCV AUC was 0.84 after incorporation of computer-extracted MRI features, and 0.85 when liquid biopsy information was added instead of the radiological MRI assessment. Adding liquid biopsy information to the clinical-radiological resulted in an estimated LOOCV AUC of 0.86. In conclusion, inclusion of liquid biopsy-derived markers in clinical-radiological prediction models may have potential to improve prediction of pCR after NAC in breast cancer.

Abstract 6701: 6-color Crystal Digital PCR for the high-plex detection of 10 ESR1 mutations in breast cancer

Introduction. ESR1 mutations have emerged as a key mechanism of resistance to endocrine therapy in estrogen-receptor-positive (ER+) breast cancer, thus detection of ESR1 mutations is crucial to monitor during patient treatment. We evaluated a novel 12plex breast cancer assay for the detection of 10 ESR1 mutations and AKT1 E17K in plasma cell-free DNA (cfDNA) using 6-color Crystal Digital PCRTM (naica® system, Stilla Technologies, France). We further compared the results with our previously reported ESR1 NAPA assay for D538G, Y537S, Y537C and Y537N mutations (Stergiopoulou et al, Cancers, 2021).

Patients and Methods. Using the 6-color Crystal Digital PCRTM breast cancer 12plex assay, we analyzed 35 plasma cfDNA samples from ER+ breast cancer patients and 10 plasma cfDNA from healthy donors (HD). We also analyzed the same cfDNA samples using the ESR1 NAPA assay.

Results. The Stilla 6-color breast cancer assay revealed in 5/35 (14,3%) ER+ cfDNA samples the AKT1_E17K and ESR1 D538G mutations. ESR1 D538G was detected in 4/35 ER+ cfDNA samples with the ESR1 NAPA assay. Direct comparison between Crystal Digital PCR™ and the ESR1 NAPA assay revealed a high concordance (97.1%) for 34/35 samples tested, for the detection of the D538G mutation, and with a higher sensitivity for the Stilla 6-color breast cancer assay. The ESR1 mutations Y537S, Y537C and Y537N were not detected by either method in any of the plasma-cfDNA samples. No AKT1 E17K or ESR1 mutations were detected in cfDNA from HD plasma.

Conclusions. The naica® system 12plex ESR1 assay is quantitative, highly sensitive and easy to perform using plasma-cfDNA samples. The use of highly multiplexed Crystal Digital PCR™ shows great promise for clinical utility for ER+ breast cancer patient monitoring.

Key words: Circulating tumor DNA; Crystal Digital PCR™, ESR1 mutations; liquid biopsy; mutation monitoring, 6-color multiplexing;

Citation Format: Stavroula Smilkou, Aliki Ntzifa, Dimitra Stergiopoulou, Quentin Blache, Myrtille Remy, Cecile Jovelet, Allison Mallory, Evi Lianidou. 6-color Crystal Digital PCR for the high-plex detection of 10 ESR1 mutations in breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6701.

Circulating Tumor DNA Genomics Reveal Potential Mechanisms of Resistance to BRAF-Targeted Therapies in Patients with BRAF-Mutant Metastatic Non-Small Cell Lung Cancer

PURPOSE

The limited knowledge on the molecular profile of patients with BRAF-mutant non-small cell lung cancer (NSCLC) who progress under BRAF-targeted therapies (BRAF-TT) has hampered the development of subsequent therapeutic strategies for these patients. Here, we evaluated the clinical utility of circulating tumor DNA (ctDNA)-targeted sequencing to identify canonical BRAF mutations and genomic alterations potentially related to resistance to BRAF-TT, in a large cohort of patients with BRAF-mutant NSCLC.

EXPERIMENTAL DESIGN

This was a prospective study of 78 patients with advanced BRAF-mutant NSCLC, enrolled in 27 centers across France. Blood samples (n = 208) were collected from BRAF-TT-naïve patients (n = 47), patients nonprogressive under treatment (n = 115), or patients at disease progression (PD) to BRAF-TT (24/46 on BRAF monotherapy and 22/46 on BRAF/MEK combination therapy). ctDNA sequencing was performed using InVisionFirst-Lung. In silico structural modeling was used to predict the potential functional effect of the alterations found in ctDNA.

RESULTS

BRAF^V600E ctDNA was detected in 74% of BRAF-TT-naïve patients, where alterations in genes related with the MAPK and PI3K pathways, signal transducers, and protein kinases were identified in 29% of the samples. ctDNA positivity at the first radiographic evaluation under treatment, as well as BRAF-mutant ctDNA positivity at PD were associated with poor survival. Potential drivers of resistance to either BRAF-TT monotherapy or BRAF/MEK combination were identified in 46% of patients and these included activating mutations in effectors of the MAPK and PI3K pathways, as well as alterations in U2AF1, IDH1, and CTNNB1.

CONCLUSIONS

ctDNA sequencing is clinically relevant for the detection of BRAF-activating mutations and the identification of alterations potentially related to resistance to BRAF-TT in BRAF-mutant NSCLC.

Outcomes in oncogenic-addicted advanced NSCLC patients with actionable mutations identified by liquid biopsy genomic profiling using a tagged amplicon-based NGS assay

Circulating tumor DNA (ctDNA)-based molecular profiling is rapidly gaining traction in clinical practice of advanced cancer patients with multi-gene next-generation sequencing (NGS) panels. However, clinical outcomes remain poorly described and deserve further validation with personalized treatment of patients with genomic alterations detected in plasma ctDNA. Here, we describe the outcomes, disease control rate (DCR) at 3 months and progression-free survival (PFS) in oncogenic-addicted advanced NSCLC patients with actionable alterations identified in plasma by ctDNA liquid biopsy assay, InVisionFirst®-Lung. A pooled retrospective analysis was completed of 81 advanced NSCLC patients with all classes of alterations predicting response to current FDA approved drugs: sensitizing common EGFR mutations (78%, n = 63) with T790M (73%, 46/63), ALK / ROS1 gene fusions (17%, n = 14) and BRAF V600E mutations (5%, n = 4). Actionable driver alterations detected in liquid biopsy were confirmed by prior tissue genomic profiling in all patients, and all patients received personalized treatment. Of 82 patients treated with matched targeted therapies, 10% were at first-line, 41% at second-line, and 49% beyond second-line. Acquired T790M at TKI relapse was detected in 73% (46/63) of patients, and all prospective patients (34/46) initiated osimertinib treatment based on ctDNA results. The 3-month DCR was 86% in 81 evaluable patients. The median PFS was of 14.8 months (12.1–22.9m). Baseline ctDNA allelic fraction of genomic driver did not correlate with the response rate of personalized treatment (p = 0.29). ctDNA molecular profiling is an accurate and reliable tool for the detection of clinically relevant molecular alterations in advanced NSCLC patients. Clinical outcomes with targeted therapies endorse the use of liquid biopsy by amplicon-based NGS ctDNA analysis in first line and relapse testing for advanced NSCLC patients.

Outcome and molecular landscape of patients with PIK3CA-mutated metastatic breast cancer

BACKGROUND

α-Selective phosphatidylinositol 3-kinase (PI3K) inhibitors improve outcome in patients with PIK3CA-mutated, hormone receptor-positive (HR+)/Her2- metastatic breast cancer (mBC). Nevertheless, it is still unclear how to integrate this new drug family in the treatment landscape.

PATIENTS AND METHODS

A total of 649 patients with mBC from the SAFIR02 trial (NCT02299999), with available mutational profiles were selected for outcome analysis. PIK3CA mutations were prospectively determined by next-generation sequencing on metastatic samples. The mutational landscape of PIK3CA-mutated mBC was assessed by whole-exome sequencing (n = 617). Finally, the prognostic value of PIK3CA mutations during chemotherapy was assessed in plasma samples (n = 44) by next-generation sequencing and digital PCR.

RESULTS

Some 28% (104/364) of HR+/Her2- tumors and 10% (27/255) of triple-negative breast cancer (TNBC) presented a PIK3CA mutation (P < 0.001). PIK3CA-mutated HR+/Her2- mBC was less sensitive to chemotherapy [adjusted odds ratio: 0.40; 95% confidence interval (0.22-0.71); P = 0.002], and presented a worse overall survival (OS) compared with PIK3CA wild-type [adjusted hazard ratio: 1.44; 95% confidence interval (1.02-2.03); P = 0.04]. PIK3CA-mutated HR+/Her2- mBC was enriched in MAP3K1 mutations (15% versus 5%, P = 0.0005). In metastatic TNBC (mTNBC), the median OS in patients with PIK3CA mutation was 24 versus 14 months for PIK3CA wild-type (P = 0.03). We further looked at the distribution of PIK3CA mutation in mTNBC according to HR expression on the primary tumor. Some 6% (9/138) of patients without HR expression on the primary and 36% (14/39) of patients with HR+ on the primary presented PIK3CA mutation (P < 0.001). The level of residual PIK3CA mutations in plasma after one to three cycles of chemotherapy was associated with a poor OS [continuous variable, hazard ratio: 1.03, 95% confidence interval (1.01-1.05), P = 0.007].

CONCLUSION

PIK3CA-mutated HR+/Her2- mBC patients present a poor outcome and resistance to chemotherapy. Patients with PIK3CA-mutated TNBC present a better OS. This could be explained by an enrichment of PIK3CA mutations in luminal BC which lost HR expression in the metastatic setting.

TRIAL REGISTRATION

SAFIR02 trial: NCT02299999.

Efficacy of tyrosine kinase inhibitors (TKIs) based on the ALK resistance mutations on amplicon-based liquid biopsy in ALK positive non-small cell lung cancer (NSCLC) patients (pts)

3055

Background: Acquired ALK resistance mutations (mut.) are the main mechanism of tyrosine kinase inhibitor (TKI) resistance (30-50%). While next-generation TKIs are more active on mut. than earlier TKIs, compound ALK resistance are associated with failure to next-generation TKIs. We evaluated the clinical utility of detecting ALK resistance mutations in blood to predict TKI efficacy. Methods: ALK positive advanced NSCLC pts were prospectively enrolled between Oct. 2015 and Aug. 2018 in 8 French institutions. Prospective samples were collected; ctDNA was analyzed by amplicon-based Inivata InVisionFirst-Lung. Results: A total of 101 pts with advanced ALK positive NSCLC were enrolled and 328 samples collected. In samples collected at TKI failure (N=74), we detected 9 single and 7 complex (≥2) ALK resistance mut. (22%), associated with EML4-ALK variant 3 (38%) vs. variant 2 (13%) vs. variant 1 (none); 30% had other somatic mut. (mainly TP53 and KRAS, PI3KCA, MET, etc.). No mutations were detected in 48% of samples (ctDNA neg). ALK mut. were more frequent after 2nd/3rd generation TKI (43% post-lorlatinib (7), 29% post-2nd gen. (31), 11% post-crizotinib (36)). ALKG1202R was the most common, as single (n=3) or complex mut. (n=4). The median overall survival (mOS) was 100.4 mo. (95% CI 41.9-158.9) and the median progression free-survival (mPFS) to subsequent line was 2.8 mo. (0.7-4.9). Patients with ctDNA neg had mOS of 105 mo. (39.3-172.1) vs. 58.5 mo. (33.1-84.0) if ≥1 ALK mut. vs. 44.1 mo. (20.0-68.2) if others ( P=0.001). Pts with the complex ALK mut. had worse OS compared to singles ALK mut. (mOS 26.9 mo. vs. 58.5 mo., P=0.001); ALK complex mut. were associated with poor efficacy to subsequent therapy (PFS <3 mo. in 57%; no cases with PFS >6 mo.) vs. single mut., with longer PFS (PFS >6 mo. in 56%). Detectable ALKG1202R mut. were associated with shorter median OS (58.3 mo.; 7.9-109.1) vs. overall population; 86% of cases developed rapid PD (PFS <3mo.) to subsequent therapy with only one durable response to lorlatinib (PFS >6mo.). Conclusions: The absence of ctDNA mutations at TKI failure was associated with prolonged OS, whereas complex ALK mutations at TKI failure may predict resistance to subsequent therapy. Larger and specifically designed studies should be performed to validate these findings.

Circulating tumor DNA analysis (ctDNA) for genomic testing in NSCLC patients with isolated CNS progression

2015

Background: Genomic DNA profiles are mandatory in advanced, treatment naive non-small cell lung cancer (NSCLC) patients (pts) and strongly recommended at progression (PD) on personalized treatment. In pts with PD limited to central nervous system (CNS), tissue biopsy is difficult and the performance of ctDNA is unknown. Methods: Clinical, molecular, imaging data of NSCLC pts included in 2 prospective studies from 01.2016 to 11.2018 at Gustave Roussy were collected. Inclusion criteria were: stage IV disease and any known tissue genomic alteration (GA) EGFR, ALK, BRAF, KRAS, HER2, ROS1, MET, PIK3CA, TP53. Plasma ctDNA collected at baseline/PD were analyzed by next-generation sequencing (NGS-InVisionFirst™-Lung) in 3 groups: pts with isolated CNS (iCNS), extra-CNS only (noCNS) or both combined (cCNS) disease. iCNS was defined as any PD to CNS, while stable/absent extra-CNS metastases (mts). ctDNA was considered positive if ≥1 GA was found. ctDNA in cerebrospinal fluid (CSF) were also collected. Results: Out of 245 pts with ≥1 ctDNA: 56 had iCNS (66 samples), 97 noCNS (127 samples) and 92 cCNS (107 samples). In this cohort, 60% were female, median age 60 years, 47% smokers; 92% had adenocarcinoma. The median number of mts sites was 3 in noCNS/cCNS groups. Proportions of tissue GA at baseline were (iCNS vs noCNS/cCNS): EGFR (50% vs 44%), ALK (30% vs 11%), BRAF (4% vs 12%), KRAS (5% vs 15%), HER2 (2% vs 5%), ROS1 (5% vs 4%). Tyrosine kinase inhibitors were used in 73% iCNS vs 61% noCNS/cCNS. Local brain treatments were performed in 43% (n = 24) vs 32% (n = 29) and leptomeningeal mts (LM) detected in 34% (n = 19) vs 8% (n = 9), in iCNS and cCNS, respectively. CtDNA was positive (+) in 52% in iCNS vs 84% in noCNS and 92% in cCNS (p < 0.0001). In iCNS, there was a non-significantly higher proportion of + ctDNA in pts with LM vs only brain disease (59 vs 48%, P = 0.44). 12/56 pts of iCNS group had serial ctDNA, being collected also at time of cCNS. In 25% of cases, a negative ctDNA at time of iCNS shifted to + at time of cCNS. In 12 iCNS pts, ctDNA was + in 6 (50%) plasma and in 10 (83%) paired CSF (p = 0.193). Conclusions: Detection of GA by plasma ctDNA is lower in NSCLC pts with isolated CNS PD. Alternative strategies (as CSF analysis) should be explored.

Real-World Utility of an Amplicon-Based Next-Generation Sequencing Liquid Biopsy for Broad Molecular Profiling in Patients With Advanced Non-Small-Cell Lung Cancer

PURPOSE

To assess the feasibility and utility of circulating tumor DNA (ctDNA) by amplicon-based next-generation sequencing (NGS) analysis in the daily clinical setting in a cohort of patients with advanced non-small-cell lung cancer (NSCLC), as an alternative approach to tissue molecular profiling.

PATIENTS AND METHODS

In this single-center prospective study, treatment-naïve and previously treated patients with advanced NSCLC were enrolled. Clinical validation of ctDNA using amplicon-based NGS analysis (with a 36-gene panel) was performed against standard-of-care tissue molecular analysis in treatment-naïve patients. The feasibility, utility, and prognostic value of ctDNA as a dynamic marker of treatment efficacy was evaluated. Results of tissue molecular profile were blinded during ctDNA analysis.

RESULTS

Of 214 patients with advanced NSCLC who were recruited, 156 were treatment-naïve patients and 58 were pretreated patients with unknown tissue molecular profile. ctDNA screening was successfully performed for 91% (n = 194) of all patients, and mutations were detected in 77% of these patients. Tissue molecular analysis was available for 111 patients (52%), and tissue somatic mutations were found for 78% (n = 87) of patients. For clinically relevant variants, concordance agreement between ctDNA and tumor tissue analysis was 95% among 94 treatment-naïve patients who had concurrent liquid and tumor biopsy molecular profiles. Sensitivity and specificity were 81% and 97%, respectively. Of the 103 patients with no tissue available, ctDNA detected potential actionable mutations in 17% of patients; of these, 10% received personalized treatment. ctDNA kinetics correlated with response rate and progression-free survival in 31 patients treated with first-line platinum-based chemotherapy.

CONCLUSION

These real-world data from a prospective study endorse ctDNA molecular profile by amplicon-based NGS as an accurate and reliable tool to detect and monitor clinically relevant molecular alterations in patients with advanced NSCLC.

Abstract 2953: Overall survival results of the single-institution molecular screening MOSCATO trial in hard-to-treat advanced cancers

Background: MOSCATO 01 (NCT01566019) is a non-randomized single institution prospective clinical trial evaluating clinical benefit of integrating comprehensive molecular profiling into clinical practice to guide treatment in advanced cancers relapsing after standard therapies. The primary outcome of this trial has been previously published. We hereby evaluate the effect of having an actionable molecular alteration on overall survival (OS) in the adult patients (pts) included in MOSCATO 01 trial, and, among those with an actionable alteration, the effect of receiving a targeted therapy matched to a molecular alteration on OS. Methods: Survival data of pts who gave written consent to be included in MOSCATO 01 trial were used for this analysis. OS was defined from date of inclusion to death, or last visit at the institution. The Inverse Probability-of-Censoring Weighting method with a propensity score was used to estimate causal effects in a COX MODEL. For actionable alteration effect, propensity score included age, sex, Royal Marsden Hospital prognostic score. For targeted therapy effect, the same variables were used for propensity score and an additional landmark time was set at 2 months to take lead guarantee-time bias into account. Actionable molecular alterations were defined by a weekly molecular tutor board. Results: Between December 2011 and March 2016, among 1035 pts included in MOSCATO trial, 948 had a tumor biopsy. Of 843 pts where molecular portrait was successful, an actionable molecular alteration has been identified in 411 pts. Of the 411 pts with actionable molecular alteration, 199 received targeted therapy matched to the identified genomic alteration. At the cut-off date of June 2017, survival data was obtained for a total of 906 pts (396 out of 411 pts with an actionable alteration and 493 out of 624 pts without). After median follow-up of 9.2 months (4.7-20.4 months), 749 deaths were observed and median OS was 7.4 months. In the MOSCATO 01 trial, pts with an actionable molecular alteration had a significantly worse OS than pts without (HR=1.51 [1.38,1.64], p&lt;0.001). Among pts with an actionable alteration, pts who received a matched targeted therapy did not have a significantly improved OS (HR=0.81 [0.65,1.01], p=0.06). Conclusion: In MOSCATO 01 trial, pts with an actionable target had significantly worse OS, while pts with a targeted treatment did not have a significantly better OS than those without. Randomized controlled trials are needed to evaluate whether customizing targeted therapy to pts with advanced tumors harboring actionable molecular alterations could improve OS.

Citation Format: Yolla El Dakdouki, Adrien Allorant, Loic Verlingue, Ludovic Lacroix, Etienne Rouleau, Nathalie Auger, Stefan Michiels, Thierry Debaere, Fabrice Andre, Gilles Vassal, Cecile Jovelet, Lambros Tselikas, Jean-Charles Soria, Antoine Hollebecque, Christophe Massard. Overall survival results of the single-institution molecular screening MOSCATO trial in hard-to-treat advanced cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2953.

Abstract 4581: Feasibility of an amplicon-based liquid biopsy for ALK and ROS1 fusions in advanced non-small cell lung cancer (NSCLC) patients

INTRODUCTION Circulating tumor DNA (ctDNA) is a surrogate material for somatic mutation detection, such as EGFR, BRAF or KRAS mutations in NSCLC patients, however the applicability of this technique for ALK and ROS1 fusion detection is poorly described. The aim of this combined analysis was to evaluate an amplicon-based ctDNA technology in a cohort of ALK and ROS1 positive NSCLC patients. METHODS ALK and ROS1 positive NSCLC patients were prospectively enrolled or retrospective specimens selected, to be included across 6 international centres. ALK/ROS1 positive status was determined by standard of care (FISH/IHC or NGS). The analysis of EML4-ALK fusions (variant 1,2,3) and ROS1 fusions (with partner genes CD74, SLC34A2, SDC4 and EZR) was performed using the InVision™ platform. RESULTS Patients included (n=65; 59 ALK, 6 ROS1): 35 (55%) females, 40 (63%) non-smokers, median age of 59 years, stage IV disease (88%) adenocarcinoma (97%). All patients were ALK/ROS positive by IHC (32), FISH (45) and/or tissue NGS (10). Samples (n=98) were collected across multiple timepoints. In total, 31 patients were fusion positive (25 ALK, 6 ROS1). Among treatment-naïve patients, sensitivity was 78% for ALK and 100% for ROS1. In contrast, fusions were detected in minority of samples (7/57) in patients responding to treatment. In patients with ctDNA positive ALK fusion (n=25): 8 patients (32%) presented the EML4-ALK variant 1; 2 (8%) the variant 2 and 15 (60%) the variant 3. In the ROS1 population (n=6), rearrangement with chromosome 5, resulting in CD74-ROS1 was seen in 4 of cases and translocation with chromosome 4 to generate SLC34A2-ROS1 occurred in 2 of cases. All patients had unique DNA fusion junctions identified and will be described, providing an insight at the DNA level of the molecular mechanisms leading to ALK and ROS1 driven lung cancers. Breakpoint microhomology was observed at the fusion junction in 50% of cases, ranging from 1 to 7bp. A 4bp insertion of non-templated DNA was seen in one case, with the remaining 47% of cases most likely the result of non-homologous end joining. Evidence for enrichment of microhomologous sequences and clustering of breaks within the introns will be investigated and reported at the conference. CONCLUSION The detection of ALK and ROS1 fusions using the amplicon-based NGS Invision liquid biopsy platform is feasible in routine clinical practice. Good sensitivity for clinically actionable ALK and ROS structural rearrangements in untreated advanced NSCLC patients was demonstrated.

Citation Format: Laura Mezquita, Yuebi Hu, Karen Howarth, Cecile Jovelet, David Planchard, Ludovic Lacroix, Aurelie Swalduz, Sandra Ortiz-Cuaran, Virginie Avrillon, Vincent Plagnol, John Beeler, Katherine Baker-Neblett, Greg Jones, Nitzan Rosenfeld, Clive Morris, Emma Green, Edward S. Kim, Maurice Perol, Pierre Saintigny, Stephen V. Liu, Geoff R. Oxnard, Benjamin Besse. Feasibility of an amplicon-based liquid biopsy for ALK and ROS1 fusions in advanced non-small cell lung cancer (NSCLC) patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4581.

Evaluation of liquid biopsies for molecular profiling in untreated patients with stage III/IV non-small cell lung cancer (NSCLC)

11540

Background: Molecular profiling is limited by tumour heterogeneity and access to sufficient tissue for comprehensive analysis. Circulating tumour DNA (ctDNA) can be used as a minimally-invasive liquid biopsy for mutation detection, quantification and monitoring for personalised treatment strategies. Methods: We recruited 110 patients into a prospectively-designed study for Stage III/IV NSCLC patients intended to initiate 1stline platinum-based chemotherapy. Blood collections (10ml K2-EDTA) were performed prior to treatment and analysed by InVision (enhanced tagged-amplicon sequencing) using a 34-gene panel. Tissue biopsies, when available, were analysed by NGS (Ion-Torrent, Sanger) for concordance analysis. To evaluate correlation with outcome, repeat blood collections were performed in selected patients. Results: 110 NSCLC pts were included (61% male, 14% never-smoker, and 70% adenocarcinoma). ctDNA profiling detected mutations in 83 pts (79%). TP53 (44%), KRAS (17%), STK11 (18%; 11/19 with KRAS/STK11) and EGFR (10%) were the commonest abnormalities detected. Additionally, MET (6%), ERBB2 (6%), PIKC3A (6%) and BRAF (4%) mutations and EGFR, MET, ERBB2 amplifications were detected in 2% of patients, respectively. 20% of the mutations detected in ctDNA were observed at < 0.5% allele fraction, with 6% between 0.03%-0.25% AF. Tissue was available in 44 pts; somatic mutations were detected in 73%. Tissue & liquid concordance was 92.3%. 10 pts (23%) reported as tissue negative had a positive liquid biopsy. 33 advanced NSCLC patients were evaluated for longitudinal serial ctDNA monitoring up to cycle 4 of chemotherapy; the ratio of mutated molecules between D1 and D42 was significantly correlated with change in RECIST 1.1 measurement at D42 (p-value = 0.002625 CI 95% 0.298, 0.875). Conclusions: ctDNA can be used as a ‘liquid biopsy’ for molecular profiling of NSCLC patients to detect clinically relevant and actionable mutations when tissue biopsy is unavailable. Liquid biopsies can be used longitudinally and may provide an early surrogate for response evaluation by radiographic RECIST.

Evaluation of liquid biopsies for molecular profiling in patients with advanced non-small cell lung cancer (NSCLC) in the relapse treatment setting

11532

Background: Molecular profiling is limited by access to sufficient tumor tissue for comprehensive analysis and due to tumor heterogeneity, the complete range of tumor DNA abnormalities may not be represented nor accurately reflect the clinical evolution of disease. Circulating tumor DNA (ctDNA) can be used as a minimally-invasive liquid biopsy for the detection, quantification and monitoring of molecular abnormalities for personalized treatment strategies. Methods: In a prospectively designed program, to date, we have recruited 227 advanced NSCLC patients having received prior therapy, with unknown molecular profile at time of blood collection. Blood collections (10ml K2-EDTA) were performed to assess molecular profile prior to or at time of relapse. Repeat samples were performed on patients initiated on treatment and followed for up to 18months. Patient samples were analyzed with InVision (enhanced tagged-amplicon sequencing) using a 34 gene panel. Interim analysis performed with full descriptive summary statistical analyses to be presented at conference. Results: ctDNA profiling detected somatic mutations in 182pts (80.2%), predominantly located in TP53 (46%), EGFR (28%), KRAS (11%) and STK11 (7%, half of which had concurrent KRAS). Of note, clinically actionable mutations were detected: T790M (25pts, median 1.4% AF), ERBB2 (8 pts), MET (8pts) and BRAF (4pts) providing eligibility for new therapy options. 20pts including 12 EGFR/T790M+ve were evaluated for ctDNA monitoring up to 18 months (median 10m); correlation between dynamic change in mutation allele fraction and clinical response was observed, especially predictive of relapse to treatment. 10 patients demonstrated SD/PR response to osimertinib treatment with T790M detection at low allele fraction (7/10 < 1% AF with 1pt at 0.08% AF). Conclusions: ctDNA can be used as a non-invasive ‘liquid biopsy’ for molecular profiling of NSCLC patients to detect clinically relevant and actionable mutations when tissue biopsy is unavailable. Liquid biopsies can be repeated as needed where tissue is not feasible, providing real-time information to support personalised treatment.

Osimertinib benefit in EGFR-mutant NSCLC patients with T790M-mutation detected by circulating tumour DNA

Background

Approximately 50% of epidermal growth factor receptor (EGFR) mutant non-small cell lung cancer (NSCLC) patients treated with EGFR tyrosine kinase inhibitors (TKIs) will acquire resistance by the T790M mutation. Osimertinib is the standard of care in this situation. The present study assesses the efficacy of osimertinib when T790M status is determined in circulating cell-free tumour DNA (ctDNA) from blood samples in progressing advanced EGFR-mutant NSCLC patients.

Material and methods

ctDNA T790M mutational status was assessed by Inivata InVision™ (eTAm-Seq™) assay in 48 EGFR-mutant advanced NSCLC patients with acquired resistance to EGFR TKIs without a tissue biopsy between April 2015 and April 2016. Progressing T790M-positive NSCLC patients received osimertinib (80 mg daily). The objectives were to assess the response rate to osimertinib according to Response Evaluation Criteria in Solid Tumours (RECIST) 1.1, the progression-free survival (PFS) on osimertinib, and the percentage of T790M positive in ctDNA.

Results

The ctDNA T790M mutation was detected in 50% of NSCLC patients. Among assessable patients, osimertinib gave a partial response rate of 62.5% and a stable disease rate of 37.5%. All responses were confirmed responses. After median follow up of 8 months, median PFS by RECIST criteria was not achieved (95% CI: 4-NA), with 6- and 12-months PFS of 66.7% and 52%, respectively.

Conclusion(s)

ctDNA from liquid biopsy can be used as a surrogate marker for T790M in tumour tissue.

Abstract 3192: Liquid biopsies for molecular profiling of mutations in non-small cell lung cancer patients lacking tissue samples

Introduction: Approximately 30% of patients with an adenocarcinoma of the lung have an actionable driver mutation. Further understanding the molecular mechanisms of acquired resistance to targeted therapies provides key information for determining subsequent treatment options. Access to tumor tissue to perform either the initial molecular profile or at the point of acquired resistance, however, is often limited. Circulating tumor DNA (ctDNA) can be used as a minimally invasive method for the detection and quantification of molecular abnormalities. We performed a prospective study to assess molecular alterations in the ctDNA of NSCLC patients in whom the initial molecular profile or profile at acquired resistance was unknown due to lack of tumor tissue biopsy or insufficient cellularity in the biopsy.

Methods: Plasma samples were collected from 52 pre-treated advanced NSCLC patients at the Gustave Roussy. DNA was extracted from &lt; 5 ml of plasma and analysed using Inivata's enhanced TAm-SeqTM assay covering regions from 35 cancer-related genes. Sequences were generated using Illumina sequencing. We also analysed plasma taken following treatments prescribed after the original molecular profile detected using plasma ctDNA.

Results: From July 2015 to October 2015, 52 patients were included (63% female, 37% never-smoker, 95% diagnosed with an adenocarcinoma subtype, 95% with stage IV disease, and 54% had EGFR mutant tumors of which 68% had mutations in exon 19 and 32% had mutations in exon 21). ctDNA profiling was successfully performed for all patients, and mutations were detected in 38 of 52 patients. The median number of mutations detected in plasma samples was 1. Within the EGFR mutant subpopulation, T790M mutations were identified including 8 acquired cases (with a concomitant C797S mutation in 1 case) and 1 primary T790M mutation. Of these patients, 5 started personalised treatment with AZD9291 based on the results of ctDNA analysis. In the other 18 patients with EGFR mutant tumors, no acquired mutations associated with resistance were detected. Other results encompassed: 2 plasma samples with EGFR mutation exon 18 (G719A, G719C) leading to initiation of afatinib in one case, 1 case with EGFR mutation exon 21 (L861Q), 1 patients with ERBB2 exon 20 insertion, 3 KRAS mutant detected in plasma (G12C, G12S, G12F), 2 STK11 mutant samples, and 1 patient with a MET mutation (exon 14) who subsequently started crizotinib.

Conclusions: ctDNA analysis with Inivata's enhanced TAm-Seq™ provides an alternative method of ‘liquid biopsy’ for obtaining molecular profile of mutations present in NSCLC patients in the absence of an invasive tissue biopsy. Liquid biopsy identified cancer mutations in 73% of the study population, and 18% of those patients subsequently received treatment tailored to the plasma ctDNA detected mutations. An update on the analysis of 75 patients will be presented during the conference.

Citation Format: Jordi Remon, Jean Charles Soria, David Planchard, Cecile Jovelet, Chloe Pannet, Ludovic Lacroix, Annas Gazzah, Andrew Lawson, Sarah Smalley, Kenth Howarth, David Gale, Emma Green, Vincent Plagnol, Nitzan Rosenfeld, Ken Oulassen, Nathalie Chaput, Benjamin Besse. Liquid biopsies for molecular profiling of mutations in non-small cell lung cancer patients lacking tissue samples. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3192.

Variation in transplacental transfer of tyrosine kinase inhibitors in the human perfused cotyledon model

BACKGROUND

The use of tyrosine kinase inhibitors (TKis) during pregnancy in humans remains rare, and little data are available on their transplacental passage. Erlotinib and gefitinib are the first-line targeted therapy in case of stage IV nonsmall-cell lung cancer with an EGFR-activating mutation. There are no data available regarding the comparative use of these TKis in pregnant patients. We aimed to compare the transplacental transfer of gefitinib, imatinib and erlotinib, using the ex vivo method of human perfused cotyledon, and to determine the placental accumulation of TKis.

MATERIALS AND METHODS

Term placentas were perfused after delivery with gefitinib, imatinib and erlotinib at targeted maternal concentrations around the steady-state plasma trough concentration (i.e. 500, 1000 and 1500 ng/ml, respectively). Samples from fetal and maternal circulations were collected in order to monitor TKis concentrations. Main transfer parameters such as fetal transfer rate (FTR), clearance index (CI) and placental uptake were assessed.

RESULTS

Mean FTR of gefitinib, imatinib and erlotinib were 16.8%, 10.6% and 31.4%, respectively. Mean CI of gefitinib, imatinib and erlotinib were 0.59, 0.48 and 0.93, respectively. Placental uptake in cotyledon was 0.030% %, 0.010% and 0.003% for gefitinib, imatinib and erlotinib, respectively, corresponding to a mean mass of 27.7 µg for gefitinib, 15.7 µg for imatinib and 6.8 µg for erlotinib.

CONCLUSION

The results suggest that TKis cross the placenta at therapeutic level. Particularly, erlotinib crosses the placenta at a higher rate than gefitinib or imatinib. All of them have a very low placental uptake. These data may suggest that gefitinib should be preferred to erlotinib for the treatment of pregnant woman with lung cancer harboring an EGFR-activating mutation, during the second and third trimesters of pregnancy.