Symptomatic Necrosis With Antibody-Drug Conjugates and Concurrent Stereotactic Radiotherapy for Brain Metastases

This cohort study investigates whether brain metastases that manifest after stereotactic radiotherapy with concurrent antibody-drug conjugates are associated with an increased risk of symptomatic radiation necrosis.

Multi-institutional analysis of aneuploidy and outcomes to chemoradiation and durvalumab in stage III non-small cell lung cancer

There is a need to identify predictive biomarkers to guide treatment strategies in stage III non-small cell lung cancer (NSCLCs). In this multi-institutional cohort of 197 patients with stage III NSCLC treated with concurrent chemoradiation (cCRT) and durvalumab consolidation, we identify that low tumor aneuploidy is independently associated with prolonged progression-free survival (HR 0.63; p=0.03) and overall survival (HR 0.50; p=0.03). Tumors with high aneuploidy had a significantly greater incidence of distant metastasis and shorter median distant-metastasis free survival (p=0.04 and p=0.048, respectively), but aneuploidy level did not associate with local-regional outcomes. Multiplexed immunofluorescence analysis in a cohort of NSCLC found increased intratumoral CD8-positive, PD-1-positive cells, double-positive PD-1 CD8 cells, and FOXP3-positive T-cell in low aneuploid tumors. Additionally, in a cohort of 101 patients treated with cCRT alone, tumor aneuploidy did not associate with disease outcomes. These data support the need for upfront treatment intensification strategies in stage III NSCLC patients with high aneuploid tumors and suggest that tumor aneuploidy is a promising predictive biomarker.

The Impact of Co-Alterations on Outcomes after Local Therapy for Patients with KRAS-Mutant Lung Adenocarcinoma Brain Metastases

PURPOSE/OBJECTIVE(S)

Brain metastases are common in NSCLC with up to 25% of patients having brain metastases (BMs) at the time of diagnosis and 30% developing BMs during their disease course. KRAS is an oncogenic driver in approximately 25% of lung adenocarcinomas. Genomic alterations co-occurring with KRAS are associated with distinct biological landscapes which may influence prognosis. Herein, we sought to identify correlations between genomic profiles, intracranial progression free survival (iPFS), and overall survival (OS).

MATERIALS/METHODS

We retrospectively reviewed 156 patients with KRAS-mutant lung adenocarcinoma BM who underwent SRS for their BMs at MSKCC from 2010-2022. Each patient had at least one tumor sample profiled with MSK-IMPACT, a custom FDA-cleared next-generation sequencing. Mutations, copy number alterations, and fusions were filtered for driver alterations using OncoKB. Survival outcomes were calculated from date of MRI indicating metastatic brain disease.

RESULTS

Of the 156 patients, 80 patients presented with BMs at diagnosis whereas 76 developed BMs during their disease course, with a median 2 lines of therapy prior to BM diagnosis. The most common KRAS mutation was G12C (n = 64; 41%), G12V (n = 26, 17%), G12D (n = 17; 11%), and G12A (n = 11; 7%). The most frequently co-altered genes were TP53 (n = 71, 46%), STK11 (n = 51, 33%), CDKN2A (n = 27, 17%), KEAP1 (n = 17, 11%), and SMARCA4 (n = 10, 6%). The presence of a KEAP1 co-occurring alteration was associated with inferior iPFS (HR 1.95, 95% CI 1.05 - 3.59, p = 0.035) and the presence of SMARCA4 was also associated with inferior iPFS (HR 2.28, 95% CI 1.05 - 4.95, p = 0.038). The presence of an STK11 mutation was associated with worse OS (HR 1.57, 95% 1.01 - 2.43, p = 0.045). In a multi-variate clinico-genomic model, KEAP1 and STK11 co-occurring alterations remained significantly associated with iPFS. Patients with KEAP1-altered tumors had an increased incidence of intracranial regional progression. The 24-month cumulative incidence of regional progression amongst KEAP1-altered tumors was 57% (95% CI, 29%-77%) compared with 37% (95% CI, 29%-46%) among KEAP1-wildtype tumors (P = 0.041). Patients with CDKN2A-altered tumors had an increased incidence of leptomeningeal disease (LMD) as a form of intracranial progression. The 24-month cumulative incidence of LMD amongst CDKN2A-altered tumors was 11% (95% CI, 2.7%-27%) compared with 4.1% (95% CI, 1.5%-8.8%) among CDKN2A-wildtype tumors (P = 0.023).

CONCLUSION

In our cohort of molecularly profiled KRAS-mutant lung adenocarcinoma BM patients treated with SRS, we found that co-occurring KEAP1 and STK11 were significantly associated with worse iPFS. We also observed that CDKN2A co-altered tumors had an increased incidence of LMD. These findings have implications for future efforts to personalize brain metastasis management based on comprehensive genomic profiling.

Prospective, Cell-Free Circulating Tumor DNA (ctDNA) Profiling in Locally Advanced Lung Cancer Treated with Chemoradiation

PURPOSE/OBJECTIVE(S)

Liquid biopsy for cell-free circulating tumor DNA (ctDNA) allows for non-invasive, comprehensive genomic profiling. We explored the utility prospective liquid biopsy for (ctDNA) in among non-small cell lung cancer (NSCLC) patients treated with definitive chemoradiation.

MATERIALS/METHODS

This prospective clinical cohort consists of unresectable, locally advanced NSCLC patients who had liquid biopsy testing prior to initiation of cancer therapy. Liquid biopsy testing was performed using a next-generation sequencing assay (MSK-ACCESS) which includes 129 genes and paired white blood cell sequencing. An FDA-recognized database (OncoKB) was utilized to classify alterations associated with radiation resistance (including KEAP1, NFE2L2, STK11, and PIK3CA) and radiation sensitivity (including ATM, ATR, BRCA1/2, ARID1A, MLH1 and other DNA Damage Repair Pathway alterations). We evaluated progression-free survival (PFS) from the completion of chemoradiation using the Log-rank test.

RESULTS

Among 25 patients with prospective ctDNA testing prior to therapy initiation, 17 patients had stage III disease (68%), 8 patients had stage II disease (32%), 18 patients had adenocarcinoma (72%), 7 patients had squamous cell carcinoma (28%), and 23 (92%) were former or current smokers. The median radiation dose was 60 Gy in 30 fractions (range: 55 to 66 Gy in 20 to 33 fractions). 76% of patients (n = 18) had one or more alterations detected (median: 3 alterations, range: 1 - 8) including genomic markers of radiation response in 2 patients in BRCA1/2 (n = 2) and radiation resistance in 1 patient in KEAP1. The most common driver alteration detected was KRAS in 24% of the cohort (n = 6). Among patients with baseline detectable ctDNA, the median PFS was 21.3 months and was not reached among patients without baseline ctDNA detection (HR 4.54, p = 0.04).

CONCLUSION

Using an institutional assay, the presence of baseline cell-free ctDNA appeared prognostic in patients with unresectable, locally advanced NSCLC treated with definitive chemoradiation. We also detected driver alterations and potential markers of radiation resistance and response using ctDNA testing. Prospective cell-free ctDNA profiling may offer pathways to therapy personalization among patients with locally advanced unresectable lung cancer.

Stereotactic body radiation therapy for sarcoma pulmonary metastases

BACKGROUND/PURPOSE

Stereotactic body radiation therapy (SBRT) is standard for patients with inoperable early-stage NSCLC. We hypothesized that SBRT for sarcoma pulmonary metastases would achieve high rates of local control with acceptable toxicity and that patients with oligometastatic disease may achieve prolonged survival following SBRT.

MATERIALS/METHODS

This retrospective review included consecutive patients at our institution treated with SBRT for sarcoma pulmonary metastases. Cumulative incidence of local failure (LF) was estimated using a competing risks framework.

RESULTS

We identified 66 patients treated to 95 pulmonary metastases with SBRT. The median follow-up from the time of SBRT was 36 months (95% CI 34 - 53 months). The cumulative incidence of LF at 12 and 24 months was 3.1% (95% CI 0.9 - 10.6%) and 7.4% (95% CI 4.0% - 13.9%), respectively. The 12- and 24-month overall survival was 74% (95% CI 64 - 86%) and 49% (38 - 63%), respectively. Oligometastatic disease, intrathoracic only disease, and performance status were associated with improved survival on univariable analysis. Three patients had grade 2 pneumonitis, and one patient had grade 2 esophagitis. No patients had ≥ grade 3+ toxicities.

CONCLUSION

To the best of our knowledge, this is the largest series of patients treated with SBRT for pulmonary sarcoma metastases. We observed that SBRT offers an effective alternative to surgical resection with excellent local control and low proportions of toxicity.

AI Serial Image Prediction of Progression-Free Survival (PFS) for Locally Advanced Non-Small Cell Lung Cancer (LA-NSCLC) Patients Treated with Chemoradiation (CRT) and Durvalumab Consolidation

PURPOSE/OBJECTIVE(S)

Patient outcomes with definitive CRT for LA-NSCLC remain poor, with no imaging biomarkers to predict benefit. Hence, we developed a serial image AI model using paired planning CT (pCT) and first week cone-beam CT (CBCT) to predict PFS and measured AI model fairness defined as the bias in the classification with respect to gender as a protected attribute.

MATERIALS/METHODS

Sixty-four consecutive patients with LA-NSCLC treated with concurrent CRT to 60 Gy in 30 fractions and durvalumab consolidation were analyzed. Three prediction models were created. A previously developed AI image foundation model [1] was pre-trained with unlabeled 6,402 3D CT scans sourced from institutional and the Cancer Imaging Archive and modified to predict PFS as a binarized outcome (high PFS > 6 months and low PFS < 6 months) using pCT scans. Serial image AI model was created by adding the first week CBCT scan. The third model measured tumor growth rate (TGR) as relative change in tumor and nodal volume from pCT to CBCT derived using a different published AI model [2]. Association with PFS using univariable and multivariable Cox regression after adjusting for age, gender, planning tumor volume, and smoking status were measured using TGR and the two AI model predictions using a cutoff of > 50% probability for low PFS. AI model fairness metrics area under receiver operating curve (AUROC), precision, sensitivity, and specificity were computed.

RESULTS

TGR was not associated with PFS on univariate (Hazard ratio [HR] of 1.515, 95% confidence interval [CI] of 0.32 to 7.26, p = 0.60) or multivariate analysis (HR: 1.58, 95% CI: 0.32 to 7.80, p = 0.58) and resulted in a Harrell's C-index of 54.7%. The serial image AI model prediction was associated with PFS in both univariable (HR: 2.12, 95% CI: 1.02 to 4.40, p = 0.045) and multivariable analysis (HR 2.39, 95% CI of 1.09 to 5.25, p = 0.029), and a C-index of 62.5%. The pCT AI model was associated with PFS in univariate (HR 2.06, 95% CI of 1.06 to 4.01, p = 0.034) but not in multivariable analysis (HR 1.89, 95% CI of 0.93 to 3.87, p = 0.08), and a C-index of 59.9%. The serial image AI model reduced the parity in classification compared to pCT AI model indicating higher fairness (Table I).

CONCLUSION

The multi-image AI model predicted PFS with slightly higher accuracy and resulted in higher fairness than the pCT AI model. These results underscore the potential for incorporating multi-imaging biomarkers to predict treatment response.

Very Low Dose Radiation Therapy for Indolent Lymphomas: Comparing "Big Boom" (4 Gy x 1) vs. "Boom Boom" (2 Gy x 2)

PURPOSE/OBJECTIVE(S)

Indolent lymphomas are exquisitely sensitive to radiation therapy (RT). Programs of 2 Gy x 2 were shown to be highly effective in controlling irradiated site(s). During the COVID-19 pandemic, the International Lymphoma Radiation Oncology Group (ILROG) proposed guidelines that offered substitution of the Boom Boom (BB) (2 Gy x 2) regimen with Big Boom (Big B) of 4 Gy x 1. This report compares our center's experience with both regimens.

MATERIALS/METHODS

We included patients with indolent lymphomas in this retrospective single institution study. After April 2020 both options of very low dose and choice of a standard full dose of 24 Gy were discussed with the patient. Patients were treated with a definitive or palliative intent depending on disease stage and prior therapy exposure. Patients treated with 24 Gy are not included in this report. Toxicity was reported as per CTCAE v4.0. Overall response rate (ORR) was assessed with Lugano PET criteria at the initial post-RT imaging. Differences between the two groups were examined using the Fisher's exact test and Mann-Whitney test.

RESULTS

We evaluated a total of 471 lesions in 386 patients, including 172 lesions (37%) treated with 4 Gy x 1 and 299 lesions (63%) treated with 2 Gy x 2. Table 1 summarizes the patient and treatment characteristics. Age at the time of RT and sex were not significantly different between the two groups. The BB cohort was more likely to have follicular lymphomas (FL) (66% vs 54%, p = 0.011), though the proportion of higher-grade FL was similar between cohorts. The ORR was similar (Big B = 86%, BB = 87%) at the first post-RT evaluation (median of 2.23 months from RT for both cohorts). There was no significant difference in the rate of complete response, partial response, stable disease, or progressive disease between the cohorts at initial post-RT imaging. For both regimens, no directly related short-term side effects were observed.

CONCLUSION

Both the 4 Gyx1 and 2 Gyx2 regimens demonstrated excellent ORR at the initial post-RT imaging assessment among patients with indolent lymphomas. While longer term follow-up is required to confirm durability of these findings, our initial experience suggests that 4 Gyx1 regimen recommended by ILROG during the pandemic is an effective treatment approach.

ctDNA-based detection of molecular residual disease in stage I-III non-small cell lung cancer patients treated with definitive radiotherapy

Background

Sensitive and reliable biomarkers for early detection of recurrence are needed to improve post-definitive radiation risk stratification, disease management, and outcomes for patients with unresectable early-stage or locally advanced non-small cell lung cancer (NSCLC) who are treated with definitive radiation therapy (RT). This prospective, multistate single-center, cohort study investigated the association of circulating tumor DNA (ctDNA) status with recurrence in patients with unresectable stage I-III NSCLC who underwent definitive RT.

Methods

A total of 70 serial plasma samples from 17 NSCLC patients were collected before, during, and after treatment. A personalized, tumor-informed ctDNA assay was used to track a set of up to 16 somatic, single nucleotide variants in the associated patient's plasma samples.

Results

Pre-treatment ctDNA detection rate was 82% (14/17) and varied based on histology and stage. ctDNA was detected in 35% (6/17) of patients at the first post-RT timepoint (median of 1.66 months following the completion of RT), all of whom subsequently developed clinical progression. At this first post-RT time point, patients with ctDNA-positivity had significantly worse progression-free survival (PFS) [hazard ratio (HR): 24.2, p=0.004], and ctDNA-positivity was the only significant prognostic factor associated with PFS (HR: 13.4, p=0.02) in a multivariate analysis. All patients who developed clinical recurrence had detectable ctDNA with an average lead time over radiographic progression of 5.4 months, and post-RT ctDNA positivity was significantly associated with poor PFS (p<0.0001).

Conclusion

Personalized, longitudinal ctDNA monitoring can detect recurrence early in patients with unresectable NSCLC patients undergoing curative radiation and potentially risk-stratify patients who might benefit most from treatment intensification.

Impact of TMB/PD-L1 expression and pneumonitis on chemoradiation and durvalumab response in stage III NSCLC

Although concurrent chemoradiation (CRT) and durvalumab consolidation has become a standard treatment for stage III non-small cell lung cancer (NSCLC), clinicopathologic and genomic factors associated with its efficacy remain poorly characterized. Here, in a multi-institutional retrospective cohort study of 328 patients treated with CRT and durvalumab, we identify that very high PD-L1 tumor proportion score (TPS) expression ( ≥ 90%) and increased tumor mutational burden (TMB) are independently associated with prolonged disease control. Additionally, we identify the impact of pneumonitis and its timing on disease outcomes among patients who discontinue durvalumab: compared to patients who experienced early-onset pneumonitis ( < 3 months) leading to durvalumab discontinuation, patients with late-onset pneumonitis had a significantly longer PFS (12.7 months vs not reached; HR 0.24 [95% CI, 0.10 to 0.58]; P = 0.001) and overall survival (37.2 months vs not reached; HR 0.26 [95% CI, 0.09 to 0.79]; P = 0.017). These findings suggest that opportunities exist to improve outcomes in patients with lower PD-L1 and TMB levels, and those at highest risk for pneumonitis.

Characterization of Central Nervous System Clinico-Genomic Outcomes in ALK-Positive Non-Small Cell Lung Cancer Patients with Brain Metastases Treated with Alectinib

INTRODUCTION

Highly effective brain-penetrant ALK-targeted tyrosine kinase inhibitors (TKIs) have been developed for the management of NSCLC patients with brain metastases (BM). Local therapy (LT) such as SRS or therapeutic craniotomy is increasingly being deferred for such patients. Herein we report detailed patient- and lesion-level intracranial outcomes and co-mutational genomic profiles from a cohort of NSCLC patients with BM treated with alectinib, with or without LT.

METHODS

We retrospectively reviewed ALK fusion-positive NSCLC patients with BMs who received alectinib at the diagnosis of BM from 1/2012 and 5/2021. Outcome variables included intracranial progression-free survival (iPFS), overall survival (OS), duration of TKI therapy, and CNS response rates. Genomic characteristics from tumor specimens were assessed with MSK-IMPACT, a next-generation sequencing (NGS)-based genomic profiling assay.

RESULTS

A total of 38 patients with 114 CNS lesions were included. Twelve of these patients also received contemporaneous LT (SRS, WBRT, or surgical resection). Maximal BM diameter in the TKI + LT group was greater (p < 0.003) but despite this difference, iPFS (TKI only, HR 1.21, 95 % CI 0.51-2.89; p = 0.66) and OS (TKI only, HR 5.99, 95 % CI 0.77-46.6; p = 0.052) were similar between groups and trended towards more favorable outcomes with the addition of LT. SMARCA4 co-alterations were associated with inferior OS (HR 8.76, 1.74-44.2; p = 0.009).

CONCLUSIONS

Our study demonstrated that patients with ALK fusion-positive NSCLC treated with TKI + LT had larger BM and higher likelihood of pre-treatment neurologic symptoms. Despite these differences, iPFS was similar between groups. Results should be interpreted with caution as our study was limited by an underpowered sample size. SMARCA4 co-alterations were associated with inferior OS and these findings warrant further investigation.

Analysis of Tumor Mutational Burden, Progression-Free Survival, and Local-Regional Control in Patents with Locally Advanced Non-Small Cell Lung Cancer Treated With Chemoradiation and Durvalumab

IMPORTANCE

The addition of consolidative durvalumab to chemoradiation has improved disease control and survival in locally advanced non-small cell lung cancer (NSCLC). However, there remains a need to identify biomarkers for response to this therapy to allow for risk adaptation and personalization.

OBJECTIVES

To evaluate whether TMB or other variants associated with radiation response are also associated with outcomes following definitive chemoradiation and adjuvant durvalumab among patients with locally advanced unresectable NSCLC.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study included consecutive patients with unresectable locally advanced NSCLC treated with chemoradiation and adjuvant durvalumab between November 2013 and March 2020 who had prospective comprehensive genomic profiling. This study was completed at a multisite tertiary cancer center. The median (IQR) follow-up time was 26 (21-36) months. Statistical analysis was conducted from April to October 2022.

EXPOSURES

Patients were grouped into TMB-high (≥10 mutations/megabase [mt/Mb]) and TMB-low (<10 mt/Mb) groups and were additionally evaluated by the presence of somatic alterations associated with radiation resistance (KEAP1/NFE2L2) or radiation sensitivity (DNA damage repair pathway).

MAIN OUTCOMES AND MEASURES

The primary outcomes were 24-month local-regional failure (LRF) and progression-free survival (PFS).

RESULTS

In this cohort study of 81 patients (46 [57%] male patients; median [range] age, 67 [45-85] years), 36 patients (44%) had TMB-high tumors (≥10 mt/Mb). Patients with TMB-high vs TMB-low tumors had markedly lower 24-month LRF (9% [95% CI, 0%-46%] vs 51% [95% CI, 36%-71%]; P = .001) and improved 24-month PFS (66% [95% CI, 54%-84%] vs 27% [95% CI, 13%-40%]; P = .003). The 24-month LRF was 52% (95% CI, 25%-84%) among patients with KEAP1/NFE2L2-altered tumors compared with 27% (95% CI, 17%-42%) among patients with KEAP1/NFE2L2-wildtype tumors (P = .05). On Cox analysis, only TMB status was associated with LRF (hazard ratio [HR], 0.17; 95% CI, 0.03-0.64; P = .02) and PFS (HR, 0.45; 95% CI, 0.21-0.90; P = .03). Histology, disease stage, Eastern Cooperative Oncology Group status, programmed cell death ligand 1 expression, and pathogenic KEAP1/NFE2L2, KRAS, and DNA damage repair pathway alterations were not significantly associated with LRF or PFS.

CONCLUSIONS AND RELEVANCE

In this cohort study, TMB-high status was associated with improved local-regional control and PFS after definitive chemoradiation and adjuvant durvalumab. TMB status may facilitate risk-adaptive radiation strategies in unresectable locally advanced NSCLC.

Overall survival with circulating tumor DNA-guided therapy in advanced non-small-cell lung cancer

Circulating tumor DNA (ctDNA) sequencing guides therapy decisions but has been studied mostly in small cohorts without sufficient follow-up to determine its influence on overall survival. We prospectively followed an international cohort of 1,127 patients with non-small-cell lung cancer and ctDNA-guided therapy. ctDNA detection was associated with shorter survival (hazard ratio (HR), 2.05; 95% confidence interval (CI), 1.74-2.42; P < 0.001) independently of clinicopathologic features and metabolic tumor volume. Among the 722 (64%) patients with detectable ctDNA, 255 (23%) matched to targeted therapy by ctDNA sequencing had longer survival than those not treated with targeted therapy (HR, 0.63; 95% CI, 0.52-0.76; P < 0.001). Genomic alterations in ctDNA not detected by time-matched tissue sequencing were found in 25% of the patients. These ctDNA-only alterations disproportionately featured subclonal drivers of resistance, including RICTOR and PIK3CA alterations, and were associated with short survival. Minimally invasive ctDNA profiling can identify heterogeneous drivers not captured in tissue sequencing and expand community access to life-prolonging therapy.

Radiation Therapy for IDH-Mutant Grade 2 and Grade 3 Diffuse Glioma: An ASTRO Clinical Practice Guideline

PURPOSE

This guideline provides evidence-based recommendations for adults with isocitrate dehydrogenase (IDH)-mutant grade 2 and grade 3 diffuse glioma, as classified in the 2021 World Health Organization (WHO) Classification of Tumours. It includes indications for radiation therapy (RT), advanced RT techniques, and clinical management of adverse effects.

METHODS

The American Society for Radiation Oncology convened a multidisciplinary task force to address 4 key questions focused on the RT management of patients with IDH-mutant grade 2 and grade 3 diffuse glioma. Recommendations were based on a systematic literature review and created using a predefined consensus-building methodology and system for grading evidence quality and recommendation strength.

RESULTS

A strong recommendation for close surveillance alone was made for patients with oligodendroglioma, IDH-mutant, 1p/19q codeleted, WHO grade 2 after gross total resection without high-risk features. For oligodendroglioma, WHO grade 2 with any high-risk features, adjuvant RT was conditionally recommended. However, adjuvant RT was strongly recommended for oligodendroglioma, WHO grade 3. A conditional recommendation for close surveillance alone was made for astrocytoma, IDH-mutant, WHO grade 2 after gross total resection without high-risk features. Adjuvant RT was conditionally recommended for astrocytoma, WHO grade 2, with any high-risk features and strongly recommended for astrocytoma, WHO grade 3. Dose recommendations varied based on histology and grade. Given known adverse long-term effects of RT, consideration for advanced techniques such as intensity modulated radiation therapy/volumetric modulated arc therapy or proton therapy were given as strong and conditional recommendations, respectively. Finally, based on expert opinion, the guideline recommends assessment, surveillance, and management for toxicity management.

CONCLUSIONS

Based on published data, the American Society for Radiation Oncology task force has proposed recommendations to inform the management of adults with IDH-mutant grade 2 and grade 3 diffuse glioma as defined by WHO 2021 classification, based on the highest quality published data, and best translated by our task force of subject matter experts.

Tumor volume as a predictor of cell free DNA mutation detection in advanced non-small cell lung cancer

Background

Cell free DNA (cfDNA) is an exciting biomarker with applications across the cancer care continuum. Determinants of cfDNA shedding dynamics remain an active research area. We performed a detailed analysis of tumor volume and factors associated with detection of cfDNA mutations.

Methods

Patients with advanced non-small cell lung cancers (NSCLCs) were prospectively enrolled on a plasma biomarker protocol. Next generation sequencing (NGS) was performed using a validated, bias-corrected, hybrid-capture panel assay of lung cancer-associated genes. Volume of tumor in different subsites and total tumor volume were determined through manual volume delineation using PET/CT and brain magnetic resonance imaging (MRI) imaging. The primary endpoint was detection of cfDNA mutation; secondary endpoints were overall survival (OS) and variant allele frequency (VAF).

Results

There were 110 patients included, 78 of whom had at least one mutation detected. Median total tumor volume for the entire cohort, patients with mutation detected, and patients with no mutation detected were 66 mL (range, 2-1,383 mL), 76 mL (range, 5-1,383 mL), and 45 mL (range, 2-460 mL), respectively (P=0.002; mutation detected vs. not). The optimal total tumor volume threshold to predict increased probability of mutation detection was 65 mL (P=0.006). Total tumor volume greater than 65 mL was a significant predictor of mutation detection on multivariate analysis (OR: 4.30, P=0.003). Significant predictors of OS were age (HR: 1.04, P=0.002), detection of cfDNA mutation (HR: 2.11, P=0.024), and presence of bone metastases (HR: 1.66, P=0.047).

Conclusions

Total tumor volume greater than 65 mL was associated with cfDNA mutation detection in patients with advanced NSCLC.

Minimal residual disease (MRD) detection by ctDNA in relation to radiographic disease progression in patients with stage I-III non–small cell lung cancer (NSCLC) treated with definitive radiation therapy

8540

Background: The standard of care for patients with inoperable early stage or locally advanced NSCLC is definitive stereotactic body radiotherapy (SBRT) or conventional radiation therapy (RT) with systemic therapy. Circulating tumor DNA (ctDNA) testing can be used for the assessment of MRD and predict risk of recurrence. Few studies have prospectively evaluated MRD detection and ctDNA dynamics specifically among patients with early or locally advanced NSCLC receiving definitive RT. Methods: In a prospective clinical cohort of patients with stage I-III NSCLC (n = 17), serial plasma samples (n = 70) were collected before and after SBRT as well as before, during, and after conventional RT with or without concurrent systemic therapy and adjuvant durvalumab. Patients were followed-up for a median of 29 months (range: 4 to 54 months) with the last serial plasma collected at a median of 5 months from completion of RT (range: 1 – 26 months). A personalized, tumor-informed multiplex PCR assay (Signatera™ bespoke mPCR NGS assay) was used for the detection and quantification of ctDNA and tracked 16 tumor variants among 16 patients and 15 tumor variants in one patient. This study evaluated the prognostic value of ctDNA, correlating MRD status with clinical outcomes, in addition to ctDNA clearance kinetics during RT. Results: Among 17 patients with early-stage and locally advanced NSCLC, baseline ctDNA was detected in 82% of patients (14/17). Clinical progression was confirmed radiographically for 53% (9/17). All events of clinical progression were detectable by ctDNA (sensitivity 100%, 0.63 – 1.0), with a median lead-time of 5.5 months for MRD detection compared to radiographic disease progression. Durable ctDNA clearance was observed in 29% (5/17) of patients, all of whom then remained recurrence-free until the end of follow-up (median 12 months; specificity 100%, 95% CI 0.6 – 1.0). Transient ctDNA clearance was observed in 3 patients, and recurrent ctDNA was detected before or at the time of disease progression in all 3. ctDNA status after treatment at a single time point and longitudinally were highly predictive of disease recurrence (p < 0.0001). Conclusions: ctDNA detection is feasible for patients with stage I-III NSCLC undergoing definitive chemoradiation. and can serve as a powerful predictive biomarker for disease recurrence. High baseline detection rate is essential for feasibility of a ctDNA-based MRD assay. Residual detectable ctDNA represents a powerful predictive tool to identify patients who might benefit from intensification of adjuvant therapy following definitive RT.

Clinical utility of next-generation sequencing-based ctDNA testing for common and novel ALK fusions

OBJECTIVES

Liquid biopsy for plasma circulating tumor DNA (ctDNA) next-generation sequencing (NGS) can detect ALK fusions, though data on clinical utility of this technology in the real world is limited.

MATERIALS AND METHODS

Patients with lung cancer without known oncogenic drivers or who had acquired resistance to therapy (n = 736) underwent prospective plasma ctDNA NGS. A subset of this cohort (n = 497) also had tissue NGS. We evaluated ALK fusion detection, turnaround time (TAT), plasma and tissue concordance, matching to therapy, and treatment response.

RESULTS

ctDNA identified an ALK fusion in 21 patients (3%) with a variety of breakpoints and fusion partners, including EML4, CLTC, and PON1, a novel ALK fusion partner. TAT for ctDNA NGS was shorter than tissue NGS (10 vs. 20 days; p < 0.001). Among ALK fusions identified by ctDNA, 93% (13/14, 95% CI 66%-99%) were concordant with tissue evaluation. Among ALK fusions detected by tissue NGS, 54% (13/24, 95% CI 33%-74%) were concordant with plasma ctDNA. ctDNA matched patients to ALK-directed therapy with subsequent clinical response, including four patients matched on the basis of ctDNA results alone due to inadequate or delayed tissue testing. Serial ctDNA analysis detected MET amplification (n = 2) and ALK G1202R mutation (n = 2) as mechanisms of acquired resistance to ALK-directed therapy.

CONCLUSION

Our findings support a complementary role for ctDNA in detection of ALK fusions and other alterations at diagnosis and therapeutic resistance settings.

Enhanced specificity of clinical high-sensitivity tumor mutation profiling in cell-free DNA via paired normal sequencing using MSK-ACCESS

Circulating cell-free DNA from blood plasma of cancer patients can be used to non-invasively interrogate somatic tumor alterations. Here we develop MSK-ACCESS (Memorial Sloan Kettering - Analysis of Circulating cfDNA to Examine Somatic Status), an NGS assay for detection of very low frequency somatic alterations in 129 genes. Analytical validation demonstrated 92% sensitivity in de-novo mutation calling down to 0.5% allele frequency and 99% for a priori mutation profiling. To evaluate the performance of MSK-ACCESS, we report results from 681 prospective blood samples that underwent clinical analysis to guide patient management. Somatic alterations are detected in 73% of the samples, 56% of which have clinically actionable alterations. The utilization of matched normal sequencing allows retention of somatic alterations while removing over 10,000 germline and clonal hematopoiesis variants. Our experience illustrates the importance of analyzing matched normal samples when interpreting cfDNA results and highlights the importance of cfDNA as a genomic profiling source for cancer patients.

Liquid biopsies allow the non-invasive detection of somatic mutations from tumours. Here, the authors develop and test MSK-ACCESS, an NGS-based clinical assay for identifying low frequency mutations in 129 genes and describe how it benefits patients in the clinic.

Overall survival with circulating tumor DNA-guided therapy in advanced non-small cell lung cancer

9009

Background: The effectiveness of circulating tumor DNA (ctDNA) at matching patients to life prolonging therapy has been studied mostly in small cohorts with limited follow up. The prognostic value of ctDNA alterations, particularly those absent on tissue, is also unclear. To address these questions, we studied survival outcomes in a prospective cohort of patients (N = 1002) with non-small cell lung cancer (NSCLC). Methods: Adults with metastatic or recurrent NSCLC were eligible if they had no known driver mutation or a known driver with progression following targeted therapy. Patients were enrolled at Memorial Sloan Kettering Cancer Center (New York, NY) starting October 21, 2016; analysis here is from a snapshot November 1, 2020. All patients had ctDNA sequenced via the Resolution ctDx Lung platform. To reduce inclusion of incidental germline mutations, we excluded non-functionally significant mutations with an allele frequency 35-65% that were present in gnomAD. Patients could also receive, at their provider’s discretion, tissue sequencing with MSK-IMPACT, which filters germline and clonal hematopoietic (CH) mutations with matched white blood cell sequencing. We performed survival analyses using Cox proportional hazards models from time of diagnosis of advanced disease to death, left truncating at time of study entry. Results: Of 1002 patients, 348 (35%) were treated with targeted therapy; in 181 of these (52%) the targetable alteration was detected in ctDNA. Patients treated with targeted therapy had prolonged survival whether matched by tissue-based methods (HR 0.39, 95%CI 0.30-0.51) or ctDNA (HR 0.47, 95%CI 0.37-0.61). These benefits persisted across multiple subgroups. ctDNA alterations themselves were associated with worse survival (HR 2.2, 95%CI 1.8-2.8), in a manner that scaled with allele fraction and burden. Of 401 patients with time-matched tissue sampling, 62 (15%) had ctDNA alterations that were absent on IMPACT (“unique” ctDNA alterations). Three such patients had unique ctDNA EGFR T790M mutations leading to changes in therapy. However, unique ctDNA alterations were generally associated with worse survival than no ctDNA alterations (HR 2.5, 95%CI 1.7-3.7) and even tissue-matched ctDNA alterations (HR 1.7, 95%CI 1.1-2.4). Of 98 unique ctDNA mutations, 48 (49%) were detectable in tissue at subthreshold levels, 12 (12%) were filtered by IMPACT as CH or germline, and 38 mutations (39%) were absent even at subthreshold levels. ctDNA alteration burden correlated with radiographic disease extent. In multivariate models with radiographic disease extent and other clinical variables, ctDNA alterations were the strongest independent predictor of worse survival. Conclusions: Our results show that ctDNA may match patients to life-prolonging targeted therapy and have prognostic importance. ctDNA may provide data about a patient’s cancer missed by spatially restricted tissue sequencing. Clinical trial information: NCT01775072.

Abstract 709: The utility of plasma ctDNA for detection of KRAS G12C and other mutations in lung cancers

Background: KRAS is the most common oncogene in lung cancer, but has historically been considered undruggable. The recent development of mutant-selective KRAS G12C inhibitors has for the first time created potential therapeutic opportunities for this unmet need. Simultaneously, circulating tumor DNA (ctDNA) is increasingly being used to detect targetable oncogenes in patients with metastatic lung cancers. There is limited data regarding the utility of plasma ctDNA in specifically identifying KRAS G12C mutations.

Methods: Plasma was collected from 599 patients with lung cancer seen at Memorial Sloan Kettering Cancer Center between 10/2016 and 1/2019. ctDNA sequencing was performed using the ctDX-Lung Assay (Resolution Bioscience; Kirkland, WA). Tissue DNA sequencing was carried out using the MSK-IMPACT assay.

Results: Mutations in KRAS (KRAS+) were detected in 129 patients (21.5%). Of patients with KRAS+ lung cancers, 116 had metastatic disease at the time of plasma testing. Plasma testing was carried out within 90 days of metastatic diagnosis in 92 of the 116 metastatic KRAS+ patients (79.3%), of whom 66 patients had both plasma and tissue sequencing available for comparison. 59 of the 66 patients (89.4%) had not had systemic treatment at the time of plasma testing. Average turn-around-time (TAT) for ctDNA testing in this cohort of 66 patients was 10 days, while average TAT for tissue sequencing was 22 days. ctDNA detected a KRAS mutation in 48 of the 66 patients (72.7%). A G12C mutation was found in the tissue and/or blood from 29 patients (43.9%), while 37 patients (56.1%) had other KRAS mutations. In one patient with a G12C mutation detected on plasma testing, no KRAS mutation or other known oncogenic drivers were found on tissue testing, though with limited tumor cells in the tissue sample. 75.6% of the patients with G12C mutations had KRAS detectable in the plasma, as compared to 70.3% of patients with other KRAS mutations (p=0.6). Within the cohort of patients with paired tissue and plasma testing, at a median follow-up of 202 days post-metastatic diagnosis, survival was longer in those patients without detectable KRAS in the plasma as compared to those patients with detectable plasma KRAS (log rank (Mantel-Cox), p&lt;0.001, log rank HR 7.9, 95% CI: 3.7-16.8).

Conclusion: Plasma testing was able to rapidly detect KRAS G12C mutations in the majority of patients with this alteration, which may guide G12C inhibitor therapy. In our cohort, patients that shed KRAS mutant DNA into the plasma had shorter survival.

Citation Format: Yonina R. Murciano-Goroff, Kathryn C. Arbour, Michael D. Offin, Hai-Yan Y. Tu, Emily S. Lebow, Tristan S. Shaffer, Caterina Bertucci, Syed A. Hosseini, Kavita Garg, Lee P. Lim, Mark Li, Jason C. Chang, Jorge S. Reis-Filho, Pedram Razavi, James M. Isbell, Gregory J. Riely, David M. Hyman, Piro Lito, Bob T. Li. The utility of plasma ctDNA for detection of KRAS G12C and other mutations in lung cancers [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 709.

Abstract 12: Characterizing KRAS G12C and other mutations in plasma ctDNA from patients with lung cancer

Background: KRAS is the most common oncogene in lung cancers, but despite decades of intense research, there are no FDA-approved drugs targeting these cancers. Recent recognition that KRAS G12C harbors a binding pocket near the mutant cysteine residue has enabled the development of a new class of allele-specific inhibitors that are currently in early-phase trials. However, the mutational landscape and clinical characteristics of KRAS G12C mutant lung cancers are not well understood. The clinical use of plasma circulating tumor DNA (ctDNA) provides an opportunity to characterize this disease.

Methods: Plasma was collected from 636 patients seen at Memorial Sloan Kettering Cancer Center between 11/2016 and 5/2019. ctDNA was extracted and analyzed using the validated 23-gene ctDx-Lung assay (Resolution Bioscience; Kirkland, WA). Categorical comparisons were carried out using Fisher’s exact test.

Results: 95 NSCLC patients were identified as having alterations in KRAS based on ctDNA analysis, of whom 93.7% were metastatic at the time of plasma testing. 81.8% and 80.6% of G12C and non-G12C patients were systemic treatment naive at the time of testing, respectively. 33 patients had KRAS G12C mutations (34.7%), and 62 had other KRAS mutations (65.3%), including mutations in G12D in 24 patients, G12V in 9 patients, Q61H in 5, G12A in 8, G12S in 7, G13C in 3, G13D in 2, G13V and G12F in one patient each, as well as both Q61L and G13C in 2 patients. 60.6% of KRAS G12C patients and 53.2% of KRAS non-G12C were female. 97% of patients with G12C mutations were former smokers as compared to 77.4% in the non-G12C group (p=0.02). Of patients with stage IV adenocarcinoma with plasma KRAS detection, 9 of 25 patients with G12C were alive at the time of data analysis (36%), while 28 of 53 (52.8%) patients with KRAS non-G12C disease were alive (p =0.23; days from metastatic diagnosis to data analysis: G12C patients: 113-608, median: 396.0; non-G12C patients: 79-2248, median: 427.5). For patients with KRAS G12C mutations, co-alterations were found in TP53 (n=12, 36.4%), as well as SNVs in ROS1 (n=2), and in ALK (n=1). In patients with non-G12C KRAS detected on plasma, co-alterations were found in TP53 (n=26, 41.9%), and PIK3CA (n=3), with additional concurrent alterations in RTKs, including one patient with EGFR K714N, one with EGFR L858R, one patient with an FGFR1 amplification, and one each with an FGFR1 and FGFR3 mutation. Alterations were also detected in MET R988C (n=1) and a MET exon 14 splice variation, with SNVs in RET (n=2), as well as in ALK, ROS1, and AKT1, with a MET as well as a RICTOR amplification in one patient each.

Conclusion: Patients with KRAS G12C mutations detected on plasma analysis were more likely to be smokers. Our data support the need for further analysis of co-alterations both in plasma and on tissue sequencing to aid the development of therapies for patients with KRAS mutations as well as to advance research on combinations of G12C inhibitors with other pathway inhibitors.

Citation Format: Yonina R. Murciano-Goroff, Emily S. Lebow, Hai-Yan Tu, Mark Li, Lee P. Lim, Kathryn C. Arbour, William Travis, David B. Solit, Marc Ladanyi, David R. Jones, Charles M. Rudin, Andres Martinez, Mackenzie L. Myers, Alexander Makhnin, Pedram Razavi, Michael D. Offin, James W. Isbell, Gregory J. Riely, David M. Hyman, Piro Lito, Bob T. Li. Characterizing KRAS G12C and other mutations in plasma ctDNA from patients with lung cancer [abstract]. In: Proceedings of the AACR Special Conference on Advancing Precision Medicine Drug Development: Incorporation of Real-World Data and Other Novel Strategies; Jan 9-12, 2020; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(12_Suppl_1):Abstract nr 12.

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.

MSK-ACCESS for noninvasive somatic mutation profiling of lung cancers utilizing circulating tumor DNA

3529

Background: Circulating cell-free DNA (cfDNA) next-generation sequencing (NGS) is a promising strategy for non-invasive molecular profiling of cancers. MSK-ACCESS (Analysis of Circulating cfDNA to Evaluate Somatic Status) is a hybridization-capture targeted NGS assay that detects somatic variants in select exons of 129 genes with matched white blood cell sequencing. We present the initial clinical experience with MSK-ACCESS among patients with advanced non-small cell lung cancer (NSCLC). Methods: Patients with stage IV NSCLC underwent prospective MSK-ACCESS testing at initial diagnosis or progression of disease on targeted therapy between June 2019 and January 2020. A subset of patients had matched tissue-based NGS testing with the MSK-IMPACT 468 gene assay. We assessed oncogenic driver detection, turnaround time, plasma-tissue concordance, and matching to therapy. National Comprehensive-Cancer Network designated driver alterations were included in evaluation of tissue-plasma concordance (EGFR, ALK, KRAS, MET, RET, BRAF, HER2, ROS1, NTRK). Turnaround time was compared by a two-sided Wilcoxon signed-rank test. Results: A total of 201 patients with NSCLC had MSK-ACCESS testing at initial diagnosis (n = 79) or following progression of disease (n = 122). The median turn-around-time from plasma collection to MSK-ACCESS report was 16 days (range: 9 – 36 days) compared to 19 days from lab receipt of tissue to report (range: 12 – 57) for MSK-IMPACT (p < 0.001). Among patients with a driver detected on MSK-ACCESS, 100% (92/92) had an identical driver detected on MSK-IMPACT. Among patients with a driver detected on MSK-IMPACT, 75% (92/123) had an identical driver detected on MSK-ACCESS. This rate was similar among patients who were treatment-naive (74%; 64/86) and had disease progression (76%, 28/37) at the time of MSK-ACCESS. MSK-ACCESS identified driver alterations that directly guided first-line targeted therapy (n = 18) with response in all patients with available radiographic follow-up (n = 10), including a patient without confirmatory tissue testing. MSK-ACCESS identified resistance alterations among patients with disease progression including EGFR T790M, EGFR C797S, ROS1 G2032R, as well as a BRAF fusion. Conclusions: MSK-ACCESS successfully identified driver alterations with high concordance to tissue-based testing, directly guided patients to therapy with clinical responses, and detected known and novel resistance mechanisms. This assay warrants further clinical development to guide and facilitate precision oncology.

Proton therapy for head and neck paragangliomas: A single institutional experience

BACKGROUND

Although slow growing, head and neck paragangliomas (HNPG) can cause significant morbidity. We evaluated the efficacy of proton therapy in the management of HNPG.

METHODS

Retrospective review of an institutional proton therapy experience of treating patients between 1997 and 2016; 37 patients and 40 tumors were included.

RESULTS

Proton therapy was delivered to a median of 50.4 Gy(RBE) (range: 45-68). Having a genetic/family predisposition for HNPG was associated with multifocal tumors (P = .02) and younger diagnosis age (P = .02). Twenty-six (70%) patients had symptom improvement posttreatment, and 65% of treated tumors showed ≥20% volumetric shrinkage. The 5-year recurrence-free and overall survival rates were both 97%. Grade 2 to grade 3 toxicities (54%) included subjective hearing impairment (19%), middle ear inflammation (14%), and dry mouth (8%). There were no grade 4-5 toxicities.

CONCLUSIONS

Patients with HNPGs can be effectively and safely treated with proton therapy with excellent tumor control, successful volumetric tumor reduction, and symptomatic improvement.