Circulating tumor DNA as a marker of recurrence risk in locoregional esophagogastric cancers with pathologic complete response

452

Background: Following neoadjuvant therapy and definitive surgery, up to one-third of patients (pts) with esophageal (E), gastroesophageal junction (GEJ), and gastric (G) adenocarcinoma with a pathologic complete response (pCR) (tumor regression grade 0 [TRG0]) will experience disease recurrence, while up to one-half of pts with a near-pCR (TRG1) experience disease recurrence. Our study aims to provide real-world evidence that postoperative circulating tumor DNA (ctDNA) is prognostic of recurrence in pts with pCR or near-pCR after curative-intent neoadjuvant treatment and surgery. Methods: We identified pts from 11 institutions with stages I-III esophagogastric cancers who completed neoadjuvant therapy and had TRG0 or TRG1 scores at the time of curative-intent surgery. Postoperative plasma samples were collected for ctDNA analysis within a 16-week molecular residual disease (MRD) window after definitive surgery and serially during routine clinical follow-up from 9/19/19 to 2/21/22. MRD by ctDNA was assessed using a personalized, tumor-informed ctDNA assay (bespoke Signatera mPCR-NGS assay). The primary outcome was recurrence-free survival (RFS), measured from the date of surgery to the first documented sign of radiographic recurrence. Survival analysis was performed using the maximum likelihood bias reduction method for Cox regression in R (version 4.1) package survival. Results: We obtained 250 blood samples from 42 pts with E (n=18), GEJ (n=16), and G (n=8) adenocarcinomas who received either neoadjuvant chemoradiation or chemotherapy. 11 pts had a pCR (TRG0), and 31 pts had a near-pCR (TRG1). For pts analyzed in the post-operative, 16-week MRD window (n=21), the presence of ctDNA correlated with a higher recurrence rate (66.7%; 2/3) compared to the absence of ctDNA (11.1%; 2/18). Detectable ctDNA was associated with a significantly shorter RFS (HR 23.0, 95% CI 2.0 – 268.1; p = 0.012). 38 pts had ctDNA analyzed at any post-MRD time point (>16 weeks after surgery) over a median follow-up of 22.3 months. With additional routine ctDNA testing at any post-MRD time point, the recurrence rate was 90.0% (9/10) in ctDNA-positive pts compared to 10.7% (3/28) in ctDNA-negative pts, exhibiting a further reduction in RFS (HR 44.4; 95% CI 5.4-366.3; p<0.001). The sensitivity and specificity of the ctDNA assay at any post-operative time point was 87.5% and 96.2%, respectively. Out of 10 ctDNA-positive pts, two (20%) converted from ctDNA-positive to ctDNA-negative with subsequent treatment. Conclusions: Within the subgroup of pts with favorable pathologic responses after neoadjuvant therapy (TRG 0-1), the presence of post-operative ctDNA identified pts with elevated recurrence risk. If validated in larger cohorts this approach may be used to select pts at risk for recurrence following neoadjuvant therapy, with potential implications for direction of adjuvant therapy.

Characterization of avoidable hospital admissions in patients with lung cancer in the immunotherapy and targeted therapy era

e21133

Background: Hospitalization is the second largest contributor of cancer care spending, and over 50% of lung cancer patients are admitted to the hospital while receiving treatment. Patients who avoid hospital admission have reduced health care costs with a higher quality of life. This is the first study that characterizes the risk factors and outcomes for avoidable hospital admissions of lung cancer patients. It is the first to examine the extent to which hospitalizations from immunotherapy and targeted therapy could be avoided. Methods: A retrospective chart review of lung cancer patients admitted January 2018 through December 2018 was conducted. Demographics, disease and treatment history, admission characteristics, outcomes, and end-of-life care utilization were recorded. Following a multidisciplinary consensus review, hospitalizations were determined “avoidable” or “unavoidable.” Generalized estimating equation logistic regression models analyzed risks and outcomes associated with avoidable admissions. Kaplan-Meier estimators examined the median overall survival (mOS) between patients with and without avoidable admissions. Results: We evaluated 319 admissions from 188 patients with a median age of 66 and 16%/84% SCLC/NSCLC. Cancer-related symptoms accounted for 66% of hospitalizations; pneumonia and other infections comprised 34%, and 32% were due to cancer-related pain, vomiting, or failure to thrive (FTT). Common causes of unavoidable hospitalizations were unexpected disease progression causing symptoms, COPD exacerbation, and infection. Of the 47 hospitalizations identified as avoidable (15%), the mOS was 1.6 months; the mOS of unavoidable hospitalizations was 9.7 months (HR 2.07; 95% CI 1.34-3.19; p < 0.001). Significant reasons for avoidable admissions included cancer-related pain (p = 0.021), hypervolemia (p = 0.033), patient desire to initiate hospice services (p = 0.011), and errors in medication reconciliation or distribution (p < 0.001). Errors in medication management caused 26% of the avoidable hospitalizations. Of admissions in patients on immunotherapy (n = 102) or targeted therapy (n = 44), 9% were due to adverse effects of treatment. Patients on immunotherapy and targeted therapy were not more likely to have avoidable hospitalizations compared to patients not on the treatments (p = 0.323 and 0.133, respectively). Patients with avoidable admissions were 3.02 times more likely to enroll in hospice within 30 days of hospitalization compared to unavoidable admissions (95% CI 1.54-5.92; p = 0.001). Conclusions: Patients on immunotherapy or targeted therapy were only rarely admitted due to side effects of treatment. Hospitalizations may be avoided with more aggressive outpatient symptom management, earlier hospice discussion with at-risk patients, and outpatient pharmacist review of medications following hospital discharge.

A phase II trial of atezolizumab (anti-PD-L1) with carboplatin in patients with metastatic triple-negative breast cancer (mTNBC)

TPS1112

Background: Patients with metastatic triple negative breast cancer (mTNBC) have limited treatment options. Recent studies with a PD-L1 inhibitor and taxane based chemotherapy have demonstrated an increase in median progression free survival (PFS) in mTNBC. While taxanes target microtubules, platinum agents directly alkylate DNA and may generate additional neoantigens to enhance anti-tumor immunity via immune checkpoint inhibition. In this study, we are evaluating the combination of carboplatin with and without atezolizumab in patients with mTNBC. Serial biopsies are poised to help elucidate biological differences in responders and nonresponders. As optimal timing of adding checkpoint inhibition to chemotherapy is debatable, the randomized, crossover design will give insight into whether priming mTNBCs with DNA damaging chemotherapy results in cellular and immune changes that lead to a greater likelihood of response. Methods: This is a randomized phase II multicenter study at seven sites within the Translational Breast Cancer Research Consortium (TBCRC). Patients with mTNBC, ECOG 0-1, and 0-1 prior regimens for mTNBC are eligible. 106 patients will be randomized 1:1 to receive atezolizumab 1200 mg plus carboplatin AUC 6 (n = 53; Arm A) or carboplatin AUC 6 alone (n = 53; Arm B) every 3 weeks until intolerable toxicity or disease progression occurs. Patients receiving carboplatin alone have the option to cross over to atezolizumab upon progression (Arm Bx). Patients will undergo clinical assessment every cycle, and tumor assessment every 3 cycles with CT scan of the chest, abdomen, and pelvis and bone scan. Core biopsies of a metastatic lesion are performed at baseline and at progression. The primary endpoint is median progression free survival (PFS) with 95% confidence intervals based on RECIST 1.1. The sample size of 106 with 1:1 randomization is powered to detect a 1.5-month difference in PFS between arms (α = 0.10, β = 0.20). Secondary endpoints include overall response rate (ORR), duration of response (DOR), clinical benefit rate, and overall survival. The PFS, ORR, and DOR will also be measured by irRECIST to account for delayed effects of atezolizumab on tumor burden. The quantification of tumor infiltrating lymphocytes (TILs) will study the prognostic effects of TILs on PFS in patients receiving atezolizumab. Biopsy-derived PD-L1 expression by IHC and RNA-seq will assess treatment-induced changes, define triple-negative subtypes, and evaluate for resistance mechanisms. To date, 89 of 106 patients are enrolled. Clinical trial information: NCT03206203 .