Role of Resin Microsphere Y90 Dosimetry in Predicting Objective Tumor Response, Survival and Treatment Related Toxicity in Surgically Unresectable Colorectal Liver Metastasis: A Retrospective Single Institution Study

Purpose: To Evaluate the correlation between tumor dosimetric parameters with objective tumor response (OR) and overall survival (OS) in patients with surgically unresectable colorectal liver metastasis (CRLM) undergoing resin-based Ytrrium-90 selective internal radiation therapy (Y90 SIRT). Materials and Methods: 45 consecutive patients with CRLM underwent resin-based Y90 SIRT in one or both hepatic lobes (66 treated lobes total). Dose volume histograms were created with MIM Sureplan® v.6.9 using post-treatment SPECT/CT. Dosimetry analyses were based on the cumulative volume of the five largest tumors in each treatment session and non-tumoral liver (NTL) dose. Receiver operating characteristic (ROC) curve was used to evaluate tumor dosimetric factors in predicting OR by Response Evaluation Criteria for Solid Tumors at 3 months post-Y90. Additionally, ROC curve was used to evaluate non-tumoral liver dose as a predictor of grade ≥ 3 liver toxicity and radioembolization induced liver disease (REILD) 3 months post Y90. To minimize for potential confounding demographic and clinical factors, univariate and multivariate analysis of survival with mean tumor dose as one of the factors were also performed. Kaplan-Meier estimation was used for OS analysis from initial Y90 SIRT. Results: 26 out of 45 patients had OR with a median OS of 17.2 months versus 6.8 months for patients without OR (p < 0.001). Mean tumor dose (TD) of the five largest tumors was the strongest predictor of OR with an area under the curve of 0.73 (p < 0.001). Minimum TD, and TD to 30%, 50%, and 70% of tumor volume also predicted OR (p’s < 0.05). Mean TD ≥ 100 Gy predicted a significantly prolonged median OS of 19 vs. 11 months for those receiving TD < 100 Gy (p = 0.016). On univariate analysis, mean TD < 100 Gy, presence of any genomic mutation, presence of MAPK pathway mutation, bilobar hepatic metastases and diffuse metastatic disease (>10 lesions per liver lobe) were found to be predictors of shorter median OS. On multivariate analysis, mean TD < 100 Gy, presence of any genomic mutation, and diffuse hepatic metastatic disease were found to be independent predictors of shorter OS. Overall, six (13.3%) patients developed grade ≥ 3 liver toxicity post Y90 of whom two (4.4%) patients developed REILD. No dose threshold predicting grade ≥ 3 liver toxicity or REILD was identified. Conclusions: Mean TD ≥ 100 Gy in patients with unresectable CRLM undergoing resin-based Y90 SIRT predicts OR and prolonged OS.

Clinical activity of durvalumab for patients with advanced mismatch repair-deficient and repair-proficient endometrial cancer. A nonrandomized phase 2 clinical trial

BackgroundIn this study, we assessed the activity of durvalumab, an antibody to programmed death ligand-1, in two cohorts of women with advanced endometrial cancers (AEC)—mismatch repair proficient (pMMR) and mismatch repair deficient (dMMR).MethodsA multicenter phase two study was performed in women with AEC with pMMR tumor progressing after one to three lines of chemotherapy and women with AEC with dMMR tumor progressing after zero to three lines of chemotherapy. Mismatch repair status was based on immunohistochemistry expression. All women received durvalumab 1500 mg given every 4 weeks until progression or unacceptable toxicity. The primary endpoint was objective tumor response by RECIST V.1.1 modified for immune-based therapeutics.ResultsSeventy-one women were recruited: 35 dMMR and 36 pMMR. Median follow-up was 19 vs 21 months in dMMR versus pMMR, respectively. Median age was 67 years. Histology in dMMR versus pMMR included endometrioid (94% vs 57%) and serous (0% vs 31%) and was high grade in 26% vs 74%. The objective tumor response rate (OTRR) in the dMMR cohort was 47% (17/36, 95% CI 32 to 63), including 6 complete responses and 11 partial responses (PRs)) vs 3% in the pMMR cohort (1/35, 95% CI 1 to 15, PR). In the dMMR cohort, durvalumab was the first-line therapy in 58% (OTRR 57%) and the second-line therapy in 39% (OTRR 38%). Median progression-free survival was 8.3 months in the dMMR cohort vs 1.8 months in the pMMR cohort. The 12-month overall survival (OS) rate was 71% in dMMR vs 51% in pMMR, with median OS not reached for dMMR vs 12 months for pMMR. Immune-related adverse events occurred in 14 women, mostly grades 1–2.ConclusionDurvalumab monotherapy showed promising activity and acceptable safety in AEC with dMMR regardless of prior lines of chemotherapy, but activity was limited in AEC with pMMR.Trial registration numbersANZGOG1601, ACTRN12617000106336, and NCT03015129.

Biochemical Tumor Marker Status and Its Role in Treatment Response in Patients Who Received High-Specific-Activity I-131 MIBG in Advanced Pheochromocytoma and Paraganglioma (PPGL): Results From a Pivotal Phase 2 Clinical Trial

Background: High-specific-activity iodine-131 meta-iodobenzylguanidine (HSA I-131 MIBG; AZEDRA®) has been approved for the treatment of adult and pediatric patients (pts) 12 years and older with iobenguane scan positive, unresectable, locally advanced or metastatic PPGL who require systemic anticancer therapy. We have previously presented data showing improved biomarker responses in pts treated with HSA I-131 MIBG. Here we report the impact of biomarker status on the study primary endpoint and objective tumor response. Methods: Pts with iobenguane-avid PPGL who were ineligible for surgery, failed prior therapy or not candidates for chemotherapy, and on a stable antihypertensive medication regimen were treated. Pts received up to two therapeutic doses, each at ~18.5 GBq (or 296 MBq/kg for pts ≤62.5 kg), administered ~90 days apart. Biomarkers were analyzed at baseline and over a 12-month efficacy period. Confirmed biochemical responses (at least ≥ 50% decrease in abnormal tumor marker value for all hypersecreted biomarkers) required subsequent responses to be identical to or better compared with the previous assessment. The primary endpoint was clinical benefit, defined as the proportion of pts with at least 50% reduction of all antihypertensive medication(s) for ≥6 months beginning during the efficacy period. The secondary endpoint, confirmed objective tumor response by RECIST, was also evaluated. Results: 68 pts received at least one therapeutic dose of HSA I-131 MIBG. For all pts with hypersecretory tumors (with a baseline biochemical marker level of ≥1.5× ULN) (n=60), a comparison of biomarker response with antihypertensive therapy yielded a correlation coefficient of 0.35 (P = 0.006; Fisher exact P = 0.012). For pts with norepinephrine only-hypersecreting tumors (n=31), a correlation coefficient of 0.47 (P = 0.008; Fisher exact P = 0.015) was observed. The overall biomarker response also correlated with objective tumor response (n=55) yielding a correlation coefficient of 0.36 (P = 0.007; Fisher exact P = 0.012) for all pts with hypersecreted biomarkers. Pts who were not biochemical hypersecretors for any biomarker (n=6) had only one responder for the primary endpoint and no objective tumor responses. Conclusions: The biomarker data from this study establish a moderate but statistically significant correlation between biomarker response following treatment with HSA I-131 MIBG and objective tumor response and durable reduction of antihypertensive therapy. This correlation was improved with norepinephrine only-hypersecreting tumors in pts with unresectable, locally advanced or metastatic PPGL.

CTC counts as a biomarker of prognosis and response in metastatic castration-resistant prostate cancer (mCRPC) from the CARD trial.

161 Background: In the prospective CARD trial (NCT02485691), cabazitaxel significantly improved radiographic progression-free survival (rPFS) and overall survival (OS) versus abiraterone or enzalutamide in patients with metastatic castration-resistant prostate cancer who had received docetaxel and progressed within 12 months with the alternative androgen-signaling-targeted inhibitor. Here we analyzed circulating tumor cell (CTC) counts as a biomarker of prognosis and response to therapy. Methods: Blood samples collected at screening (SC), Cycle 2 (C2) Day 1, and end of therapy were sent to Epic Sciences for CTC analysis. The association between CTC counts, defined as any cytokeratin-positive, CD45-negative cell, and clinical outcomes were pre-specified and analyzed using a multivariate Cox model for time-to-events (rPFS, OS) or a Χ2 test for categorical outcomes (objective tumor response). Results: Of the 255 patients randomized, 237 (92.9%) had evaluable samples at SC and 213 (83.5%) at C2. CTCs ≥ 1 were detected in 204 samples at SC (86%) and 178 samples at C2 (84%), with a median (interquartile range) count per mL of blood of 4.1 (1.3–14.2) and 5.2 (1.5–17.3), respectively. At baseline, higher CTC counts were associated with higher values of lactate dehydrogenase (P = 0.014), alkaline phosphatase (P < 0.001), and prostate-specific antigen (P < 0.001). High CTC counts, measured as a continuous variable at SC (all arms combined) were associated with a shorter OS (P = 0.03), but not rPFS (P = 0.7). However, favorable changes in absolute CTC count from SC to C2, all arms combined, were associated with longer rPFS (P = 0.03). Conversion from high (≥ 3) to low (< 3) CTC count at C2 or maintenance of a low CTC count at C2 was associated with objective tumor response (P = 0.007). Analysis of the associations of CTC androgen receptor variant 7, chromosomal instability, heterogeneity status (Shannon Index), single-cell genotypes (e.g. retinoblastoma/phosphatase and tensin homolog copy-loss), and the presence of CTCs with small-cell/neuroendocrine morphology is ongoing. Conclusions: This preplanned analysis of the CARD trial confirms that baseline CTC counts, measured by Epic Sciences platform, are prognostic. Moreover, early favorable changes in CTC counts from baseline to C2 are associated with response to therapy. Funding: Sanofi. Clinical trial information: NCT02485691.

Enhanced efficacy of mesothelin-targeted immunotoxin LMB-100 and anti–PD-1 antibody in patients with mesothelioma and mouse tumor models

LMB-100 is an immunotoxin targeting the cell surface protein mesothelin, which is highly expressed in many cancers including mesothelioma. Having observed that patients receiving pembrolizumab off protocol after LMB-100 treatment had increased tumor responses; we characterized these responses and developed animal models to study whether LMB-100 made tumors more responsive to antibodies blocking programmed cell death protein 1 (PD-1). The overall objective tumor response in the 10 patients who received PD-1 inhibitor (pembrolizumab, 9; nivolumab, 1) after progression on LMB-100 was 40%, and the median overall survival was 11.9 months. Of the seven evaluable patients, four had objective tumor responses, including one complete response and three partial responses, and the overall survival for these patients was 39.0+, 27.7, 32.6+, and 13.8 months. When stratified with regard to programmed death ligand 1 (PD-L1) expression, four of five patients with tumor PD-L1 expression had objective tumor response. Patients with positive tumor PD-L1 expression also had increased progression-free survival (11.3 versus 2.1 months, P = 0.0018) compared with those lacking PD-L1 expression. There was no statistically significant difference in overall survival (27.7 versus 6.8 months, P = 0.1). LMB-100 caused a systemic inflammatory response and recruitment of CD8+ T cells in patients’ tumors. The enhanced antitumor effects with LMB-100 plus anti–PD-1 antibody were also observed in a human peripheral blood mononuclear cell–engrafted mesothelioma mouse model and a human mesothelin–expressing syngeneic lung adenocarcinoma mouse model. LMB-100 plus pembrolizumab is now being evaluated in a prospective clinical trial for patients with mesothelioma.

Pressurized IntraPeritoneal Aerosol Chemotherapy (PIPAC)-directed treatment of peritoneal metastasis in end-stage colo-rectal cancer patients

BackgroundPressurized IntraPeritoneal Aerosol Chemotherapy (PIPAC) represents a novel approach to intraperitoneal chemotherapy. Hereby results, obtained with PIPAC in patients with advanced peritoneal metastasis (PM) from colorectal cancer (CRC), are presented.MethodsData from CRC patients (n = 24) included in the prospective PIPAC-OPC1 and PIPAC-OPC2 trials are reported. Oxaliplatin 92 mg/m2 was administered at 4-6-week intervals. A CE certified nebulizer was used to aerosolize the chemotherapeutics. Outcome criteria were objective tumor response, survival and adverse events.ResultsRetrospective analysis of 74 PIPAC procedures carried out in 24 consecutive patients with PM from CRC included from October 2015 to February 2019. Five patients had still the primary tumor in situ, and 22 patients had received palliative systemic chemotherapy. Nineteen patients completed more than two PIPAC procedures, and objective tumor response according to the histological Peritoneal Regression Grading Score (PRGS) was observed in 67% of the patients, while 21% had stable disease. Four patients (21%) had complete response (mean PRGS = 1 and negative cytology). We recorded a median survival of 37.6 (range 7.3–48.9) months from the time of PM diagnosis, whereas it was 20.5 (range 0.13–34.7) months following the first PIPAC session. Minor postoperative complications were noted, and few were considered causally related to the PIPAC treatment. However, two cases of severe postoperative complications were recorded (urosepsis and iatrogenic bowel perforation).ConclusionsPIPAC with low-dose oxaliplatin can induce objective tumor regression in selected patients with advanced PM from colorectal cancer.

Evaluation of Ki67 and other predictors of survival in metastatic neuroendocrine tumor (NET) to the liver treated with Y90 radioembolization.

e15687 Background: Ki67 index is a predictor of survival in patients with metastatic neuroendocrine tumor (NET). The purpose of this study is to evaluate Ki67 index and other potential predictors of overall survival (OS) in patients with NET metastases to the liver treated with Y90 radioembolization. Methods: In an institutional review board-approved retrospective study, consecutive patients with NET metastases to the liver who were treated with Y90 radioembolization from 2013-2018 at a single institution were evaluated. Patients with documented Ki67 index were stratified according to 2017 World Health Organization (WHO) grading based on Ki67 index (G1: < 3%, G2: 3-20%, G3: > 20%). Age, gender, and objective tumor response on post Y90 imaging were also evaluated as potential predictors of survival after Y90. Objective tumor response was evaluated at 1 and/or 3 months post Y90 with multiphase MRI utilizing Response Evaluation Criteria for Solid Tumors (RECIST). Overall survival (OS) from time of Y90 was analyzed using Kaplan-Meier estimation. Predictors of survival were evaluated using log-rank test with p < 0.05 as the statistically significant level. SPSS software v. 25 (IBM Corporation, Armonk, NY) was used for all statistical analysis. Results: A total of 77 patients were identified; 36 (47%) had a documented Ki67 index from either their primary tumor, liver metastasis, or both. Primary tumor site included pancreatic (n = 10), small bowel (n = 7), pulmonary (n = 5), gastric (n = 3), large bowel (n = 3), and renal (n = 1). A primary site was not identified in several patients (n = 7).G1 tumors comprised 31% (n = 11) of patients, while G2 and G3 tumors made up 50% (n = 18) and 19% (n = 7) of the cohort, respectively. Median overall survival (OS) of the entire cohort was 51.1 months. Median OS in patients was 63.0 months in G1 tumors, 51.1 months in G2 tumors, and 3.1 months in G3 tumors (p < 0.001). Objective response on initial MRI follow-up after Y90 radioembolization also predicted prolonged OS (51.2 months versus 17.9 months, p < 0.001). Age at time of diagnosis and gender were not predictors of survival after Y90 radioembolization. Conclusions: WHO grading based on KI67 index and objective tumor response appear to be predictors of prolonged survival in patients with metastatic NET to the liver treated with Y90 radioembolization.