Molecular response assessment using circulating tumor DNA (ctDNA) in advanced solid tumors

The therapeutic landscape for patients with advanced malignancies has changed dramatically over the last twenty years. The growing number of targeted therapies and immunotherapeutic options available have improved response rates and survival for a subset of patients, however determining which patients will experience clinical benefit from these therapies in order to avoid potential toxicities and reduce healthcare costs remains a clinical challenge. Cell-free circulating tumor DNA (ctDNA) is shed by tumor cells into systemic circulation and is already an integral part of routine clinical practice for the non-invasive tumor genotyping in advanced non-small cell lung cancer as well as other malignancies. The short half-life of ctDNA offers a unique opportunity to utilize early on-treatment changes in ctDNA for real-time assessment of therapeutic response and outcome, termed molecular response. Here, we provide a summary and review of the use of molecular response for the prediction of outcomes in patients with advanced cancer, including the current state of science, its application in clinic, and next steps for the development of this predictive tool.

Association Between Availability of Molecular Genotyping Results and Overall Survival in Patients With Advanced Nonsquamous Non-Small-Cell Lung Cancer

PURPOSE

Current guidelines recommend molecular genotyping for patients newly diagnosed with metastatic nonsquamous (mNSq) non-small-cell lung cancer (NSCLC). The association between availability of molecular genotyping before first line (1L) therapy and overall survival (OS) is not known.

METHODS

We conducted a real-world cohort study using electronic health records in patients newly diagnosed with mNSq NSCLC. Cox proportional-hazards multivariable regression models were constructed to examine the association between OS and test result availability before 1L therapy, adjusting for covariates. Additional analyses were conducted to assess the consistency and strength of the relationship. Multivariable logistic regression models were used to examine the association between concurrent tissue and plasma testing (v tissue alone) and result availability.

RESULTS

Three hundred twenty-six patients were included, 80% (261/326) with results available before 1L (available testing group), and 20% (65/326) without results available (unavailable testing group). With 14.2-month median follow-up, patients in the available testing group had significantly longer OS relative to the unavailable testing group (adjusted hazard ratio, 0.43; 95% CI, 0.30 to 0.62; P < .0001). The adjusted odds of availability of results before 1L therapy was higher with concurrent tissue and plasma testing (v tissue testing alone; adjusted odds ratio, 2.06; 95% CI, 1.09 to 3.90; P = .026).

CONCLUSION

Among patients with mNSq NSCLC in a real-world cohort, availability of molecular genotyping results before 1L therapy was associated with significantly better OS. Concurrent tissue and plasma testing was associated with a higher odds of availability of results before 1L therapy. These findings warrant renewed attention to the completion of molecular genotyping before 1L therapy.

Improving comprehensive genotyping in patients with newly diagnosed non-squamous NSCLC: Results from a prospective trial of a behavioral nudge intervention

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Background: Despite current guidelines, less than 50% of patients with metastatic (m) non-squamous (NSq) NSCLC undergo comprehensive molecular genotyping. At our institution, based on improved comprehensiveness of genotyping with use of concurrent tissue (T) and plasma (P) next generation sequencing (NGS), we designed an electronic medical record (EMR)-based “nudge intervention” to auto-generate an order for P NGS at the time of initial consultation, while T NGS was carried out reflexively based on institutional pathways. Methods: A prospective study was conducted at the Abramson Cancer Center and 2 community sites within the University of Pennsylvania Health System after IRB approval. A provider team-focused EMR-based “nudge intervention” was designed to order P NGS at the time of new patient consultation. Eligible patients for the nudge were identified using an EMR based checklist, that included 3 criteria i. newly diagnosed, ii. treatment naïve, iii. mNSq NSCLC. Results from the intervention period (4/2021-12/2021) were compared to baseline data from similar patients treated at our institution between 01/2019 and 03/2021. Categories of NCCN guideline recommended molecular genotyping were defined as: i) comprehensive: EGFR, ALK, BRAF, ROS1, MET, RET, NTRK testing, and ii) incomplete or no testing performed. The proportion of patients with comprehensive molecular genotyping prior to 1st-line therapy were compared in the pre- and post-intervention groups using the chi-square test. Results: 526 patients with mNSq NSCLC were included in this analysis: 381 in the pre-intervention cohort, 145 in the post-intervention cohort. After implementation of the EMR-based nudge, a higher proportion of patients underwent concurrent T+P testing resulting in improved comprehensive molecular genotyping. In addition, a greater proportion of patients had comprehensive genotyping available prior to 1st-line therapy in the post-intervention vs pre-intervention cohort (Table). Conclusions: Across 3 practice sites, a provider team-focused EMR-based nudge intervention was associated with a significantly higher proportion of patients with mNSq NSCLC undergoing comprehensive molecular genotyping, both overall and prior to 1st-line therapy. These findings demonstrate that behavioral, EMR-based nudges can promote guideline concordant diagnostic testing at both community and academic sites and should be studied further as a tool to improve rates of molecular testing in NSCLC.[Table: see text]

Efficacy of osimertinib in patients with EGFR mutant lung cancer harboring the uncommon exon 19 deletion, L747_A750>P

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Background: EGFR exon 19 deletions (del19) are largely considered to have uniform sensitivity to EGFR tyrosine kinase inhibitors (TKIs). Approximately 70% of del19 tumors harbor the most common deletion, E756_A750del; however, many “uncommon” variants comprise the remainder of this group. In preclinical studies, the uncommon del19, L747_A750 > P, demonstrates diminished sensitivity to the third generation TKI, osimertinib [. Identifying differences in clinical outcomes with osimertinib treatment could have therapeutic implications for patients (pts) with EGFR del19 non-small cell lung cancer (NSCLC). Methods: We conducted a multi-center retrospective cohort study of pts with metastatic EGFR del19 NSCLC treated with osimertinib. We compared progression free survival (PFS, time from TKI initiation to clinically significant growth of existing lesions or new lesions on imaging or death) and overall survival (OS) of pts with tumors harboring E746_A750del and L747_A750 > P who received osimertinib in the first line (1L) or in second or later lines of therapy and were T790M+ (≥2L). The Kaplan Meier method and Cox model were used to estimate PFS and OS, and multivariable logistic regression was used to estimate the odds of achieving PFS > 12 months. Multivariable analyses adjusted for baseline covariates- age, sex, race, and smoking. Results: From March 2013 to December 2021, 86 pts with EGFR E746_A750del and 36 with L747_A750 > P were treated with osimertinib. For 1L osimertinib, E746_A750del was associated with significantly prolonged PFS vs. L747_A750 > P (median 21.3 months (95% CI 17.0-31.7) vs. 11.7 months (10.8-29.4)) in the adjusted analysis (hazard ratio [HR] 0.52 [95% CI, 0.28-0.98, p = 0.043]). Pts with the common del19 mutation were more likely to achieve PFS > 12 months with 1L osimertinib than those with the L747_A750 > P mutation (Odds Ratio 4.14 (1.41-12.15), p 0.0097). OS exhibited a similar trend with a median OS that that was not reached (NR) at 40 months of follow-up among those with E746_A750del vs 26 months for L747_A750 > P (adjusted HR 0.52 [95% CI, 0.23-1.19], p = 0.120). For pts treated with ≥2L osimertinib, there was also a trend towards favorable PFS and OS for pts with tumors harboring E746_A750del. Conclusions: The del19 mutation L747_A750 > P is associated with inferior PFS compared to the common E746_A750del mutation in pts treated with 1L osimertinib. Understanding differences in osimertinib efficacy among EGFR del19 subtypes could alter management of these pts in the future.[Table: see text]

Association of comprehensive molecular genotyping and overall survival in patients with advanced non-squamous non-small cell lung cancer

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Background: Current guidelines recommend comprehensive molecular genotyping for newly diagnosed patients (pts) with metastatic non-squamous (non-Sq) NSCLC. We have previously demonstrated that concurrent plasma (P) and tissue (T) based next-generation sequencing (NGS) improves detection of clinically actionable mutations in pts with advanced NSCLC. We analyzed the impact of concurrent T+P NGS on comprehensiveness of molecular genotyping and on overall survival (OS). Methods: A retrospective cohort study of pts with newly diagnosed stage IV non-Sq NSCLC who received therapy at our institution between 01/2019 and 12/2020 was performed. Categories of NCCN guideline testing were defined, i) comprehensive: EGFR, ALK, BRAF, ROS1, MET, RET, and NTRK testing, ii) incomplete: 2-6 genes tested, and iii) no testing performed. The proportion of pts with comprehensive molecular testing performed, prior to 1st-line therapy and by detection modality (T NGS vs. T+P NGS), were compared using Fisher’s exact test. Median OS was estimated using Kaplan-Meier methodology from diagnosis to death or censored at most recent follow-up. Results: 335 patients were included in this analysis, 98.5% (330/335) underwent molecular testing: either comprehensive: n = 291 (86.9%), incomplete testing: n = 39 (11.6%); or no testing n = 5 (1.5%). Testing with T NGS was completed in 32.7% (108/330); 67.2% (222/330) underwent concurrent T+P NGS. These groups were well balanced for baseline characteristics, with the exception of a higher number of never smokers in T+P vs. T NGS (30.2% vs. 14.8%, p < 0.0001). Proportion of pts with comprehensive molecular testing was higher among pts with T+P NGS: 99.5% (221/222) vs. T NGS: 64.8% (70/108), p < 0.0001. All pts with T+P NGS testing had results available prior to 1st line therapy; 100% (204/204) compared to 60.7% (51/84) for T NGS, p < 0.0001. With median follow up of 20.5 months (mos, range 0.3 - 33.1), median OS was 18.6 mos. Median OS for pts tested with T+P NGS vs T alone was numerically longer at 23.2 vs. 14.1 mos, but not statistically significant (p = 0.078). However, regardless of testing modality, patients with comprehensive molecular genotyping had superior OS compared to those with incomplete or no testing (22.1 mos vs. 11.6 mos, p = 0.017). The institution of oral targeted therapy had no bearing on this difference in OS (test for interaction, p = 0.6509). Conclusions: Performance of concurrent T+P NGS testing was associated with a higher likelihood of comprehensive molecular genotyping, as well as improved availability of results, including prior to first line therapy. Patients with comprehensive genotyping have improved OS compared to patients with incomplete or no testing. These results support implementation of a concurrent T+P NGS approach upon initial diagnosis of metastatic non-Sq NSCLC.

Incorporation of plasma-based next-generation sequencing to improve guideline-concordant molecular testing in patients with newly diagnosed metastatic nonsquamous non-small cell lung cancer

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Background: Current NCCN guidelines recommend comprehensive molecular profiling for all newly diagnosed patients with metastatic non-squamous NSCLC to enable the delivery of personalized medicine. We have previously demonstrated that incorporation of plasma based next-generation gene sequencing (NGS) improves detection of clinically actionable mutations in patients with advanced NSCLC (Aggarwal et al, JAMA Oncology, 2018). To increase rates of comprehensive molecular testing at our institution, we adapted our clinical practice to include concurrent use of plasma (P) and tissue (T) based NGS upon initial diagnosis. P NGS testing was performed using a commercial 74 gene assay. We analyzed the impact of this practice change on guideline concordant molecular testing at our institution. Methods: A retrospective cohort study of patients with newly diagnosed metastatic non-squamous NSCLC following the implementation of this practice change in 12/2018 was performed. Tiers of NCCN guideline concordant testing were defined, Tier 1: complete EGFR, ALK, BRAF, ROS1, MET, RET, NTRK testing, Tier 2: included above, but with incomplete NTRK testing, Tier 3: > 2 genes tested, Tier 4: single gene testing, Tier 5: no testing. Proportion of patients with comprehensive molecular testing by modality (T NGS vs. T+P NGS) were compared using one-sided Fisher’s exact test. Results: Between 01/2019, and 12/2019, 170 patients with newly diagnosed metastatic non-Sq NSCLC were treated at our institution. Overall, 98.2% (167/170) patients underwent molecular testing, Tier 1: n = 100 (59%), Tier 2: n = 39 (23%), Tier 3/4: n = 28 (16.5%), Tier 5: n = 3 (2%). Amongst these patients, 43.1% (72/167) were tested with T NGS alone, 8% (15/167) with P NGS alone, and 47.9% (80/167) with T+P NGS. A higher proportion of patients underwent comprehensive molecular testing (Tiers 1+2) using T+P NGS: 95.7% (79/80) compared to T alone: 62.5% (45/72), p < 0.0005. Prior to the initiation of first line treatment, 72.4% (123/170) patients underwent molecular testing, Tier 1: n = 73 (59%), Tier 2: n = 27 (22%) and Tier 3/4: n = 23 (18%). Amongst these, 39% (48/123) were tested with T NGS alone, 7% (9/123) with P NGS alone and 53.6% (66/123) with T+P NGS. A higher proportion of patients underwent comprehensive molecular testing (Tiers 1+2) using T+P NGS, 100% (66/66) compared to 52% (25/48) with T NGS alone (p < 0.0005). Conclusions: Incorporation of concurrent T+P NGS testing in treatment naïve metastatic non-Sq NSCLC significantly increased the proportion of patients undergoing guideline concordant molecular testing, including prior to initiation of first-line therapy at our institution. Concurrent T+P NGS should be adopted into institutional pathways and routine clinical practice.