Molina, Julian R.

7073 Background: In preclinical studies, combinations of bortezomib and RT result in synergistic tumor killing (Cancer Chemother Pharmacol. 2007;59:207-15). Our group reported the results from the phase I portion of this study previously (J Clin Oncol. 200;28 (suppl; abstr 7085)). Based on these data, we undertook a phase II study of bortezomib in combination with paclitaxel/CBCDA and RT. Methods: Based on results from our previously reported phase I trial, systemic therapy included bortezomib (1.2 mg/m² IV days 1,4,8,11), paclitaxel (175 mg/m² IV day 2), and carboplatin (CBCDA; AUC=6 day 2) given every 3 weeks for 2 cycles. Thoracic radiotherapy (RT) included 60Gy/30 daily fractions starting day 1. The primary endpoint was the 12-month survival rate. If 41 or more of these 60 patients (68%) were alive at least 12 months after study entry, the trial would be deemed as positive and further study would be warranted. Results: 27 pts were enrolled to the phase II portion: M/F=17/10; stage IIIA/IIIB=13/14; ECOG PS 0/1=9/18; and median age: 58 (range 43-79). 18 pts (67%) completed therapy per protocol. At a planned interim analysis, 23 of 26 evaluable patients (88.5%, 95% CI: 70-98%) survived for at least 6 months, which exceeded the boundary of 21 or more needed to continue to full accrual. This trial could have continued per protocol, but was closed early due to slow accrual. With a median follow-up of 15.0 months in the 17 patients still alive, the 12-month survival rate was 71% (95% CI: 49 – 85). The median OS was 19 months (95% CI: 11 – no upper). Grade 3 or higher adverse events (regardless of attribution) were reported in 22 (82%) patients. Grade 4/5 adverse events were reported in 15 (56%) patients. There was one grade 5 event (pneumonitis). The most common (5 or more patients) grade 3/4 adverse events were fatigue (22%), leukopenia (63%), neutropenia (67%), and thrombocytopenia (44%). Conclusions: The addition of bortezomib resulted in high levels of severe hematologic toxicity, but also demonstrated evidence of activity with a 12-month survival rate of 71% and a median OS of 19 months. Further testing of this regimen in a larger study appears warranted.

14044 Background: XL647 is an orally bioavailable small molecule inhibitor of multiple receptor tyrosine kinases involved in tumorigenesis, angiogenesis, and metastasis, including EGFR/ErbB1, ErbB2/HER2, VEGFR2/KDR, and EphB4. In a previous Phase I study, the MTD was 350 mg when XL647 was dosed orally for 5 consecutive days every 14 days. Of 41 pts treated, one pt with NSCLC achieved a PR and 14 pts had prolonged stable disease (3.5–14+ months). The purpose of the present study is to determine the MTD of XL647 administered orally on a continuous daily schedule. Methods: Pts are enrolled in successive cohorts to receive XL647 daily for repeated 28 day cycles. PK sampling is performed to determine Cmax, and AUC at each dose level. Plasma samples are analyzed by ELISA for mechanism-of-action related molecules. Eyebrow hair bulbs are being evaluated by IHC to monitor effects of XL647 on signal transduction pathways downstream of EGFR. Tumor response is assessed every 8 weeks by RECIST. Pts remain on study until PD or unacceptable AEs. Results: Twelve pts have been enrolled. The starting dose was 75 mg (n=3) and has been escalated to150 mg (n=3), 200 mg (n=3) and 300 mg (n=3). To date, dose escalation continues as no DLTs have occurred and the MTD has not been determined. Ten pts remain on study, including 4 with stable disease for at least 3 months. In cohort 2, eyebrow samples from 3 pts were analyzed. XL647 caused a significant reduction in the phosphorylation of the EGFR downstream signaling kinases AKT (up to 73%) and ERK (up to 78%) in 2/3 and 3/3 pts, respectively. Preliminary analysis of potential plasma protein biomarkers from pts in cohorts 1 and 2 showed a trend towards upregulation of PlGF plasma levels in 4/6 pts during XL647 treatment. Conclusions: XL647 is well-tolerated when administered daily at doses tested to date. Dose escalation will continue until the MTD is defined. Analysis of eyebrow samples demonstrated its feasibility as a potential surrogate epidermal tissue for assessing inhibition of EGFR downstream targets by XL647. Updated safety, PK and pharmacodynamic results will be presented. [Table: see text]

7547 Background: Sorafenib is a multikinase inhibitor with single-agent activity in previously treated NSCLC. In an effort to evaluate its single agent activity in previously untreated NSCLC, the NCCTG undertook a front-line “window of opportunity” study. Materials and Methods: Patients with stage IIIB (pleural effusion) or stage IV NSCLC received sorafenib dosed at 400 mg BID continuously, with a cycle defined as 4 weeks. Patients were evaluated weekly during the first 2 cycles with those who progressed rapidly going on to receive standard chemotherapy. Based on a two-stage Fleming design, if only at most 1 confirmed response was observed in the first 20 patients enrolled to stage I, the regimen would be considered ineffective. If 2 or more responses were observed, the study would proceed to stage 2 and accrue an additional 22 patients. If 5 or more confirmed responses were observed, the regimen would be recommended for further testing. Results: The study did not meet the stage I efficacy criteria (only 1 confirmed partial response in the first 20 patients) and was permanently closed after enrolling 25 evaluable patients [15 females, 10 males; 4 stage IIIB, 21 stage IV; median age 67 (45–85)]. 2 patients are still receiving treatment (14 and 15 months). No grade 3 or higher hematologic adverse events were observed. Thirteen (52%) patients had a grade 3 non-hematologic adverse event with fatigue (20%), diarrhea (8%), and dyspnea (8%) being the most common. There was one grade 4 pulmonary hemorrhage. A total of 3 (12%) PRs; and 7 (28%) SD were observed in the 25 patients 7 (28%) patients were progression- free at 24 weeks. Median survival and median time to progression were 8.8 and 2.9 months respectively. Conclusion: While the pre- specified efficacy endpoints were not met, the objective response rate of 12% and median survival of 8.8 months suggest that single agent sorafenib has activity similar to two-drug combinations. The feasibility and utility of the “window of opportunity” design in estimating the activity of novel compounds was demonstrated. Finally, the single-agent activity of sorafenib argues for combination studies with standard chemotherapy agents. No significant financial relationships to disclose.

3598 Background: Drug resistance to topotecan can be the result of BCRP/ABCG2 expression. BCRP is a member of the ABC transporter family that pumps anticancer drugs out of the cell. Lapatinib is a potent and selective dual inhibitor of epidermal growth factor receptor (EGFR or ErbB1) and ErbB2 (Her2/Neu). 4-aminoquinazoline tyrosine kinase inhibitors have been shown to enhance the cytotoxicity of topotecan through inhibition of BCRP-mediated drug efflux in cancer cells. Methods: Thirty-seven patients with advanced stage cancers were enrolled at escalating dose levels of lapatinib and topotecan in cohorts IA, IB and IIB (MTD). Treatment schedule included lapatinib (750 - 1500 mg/d) daily for 21 (cohort IA) or 28 days (cohort IB) and topotecan (2.4 - 4.0 mg/ m2), days 1, 8 and 15; cycles were repeated every 28 days. Three patients were treated at each dose level, 18 on cohort IA, 9 on cohort IB and 10 at MTD (cohort IIB). Assessments of toxicity were performed with each cycle and clinical response was determined per RECIST criteria every other cycle. Results: The MTD for cohorts IA and IB was reached at a dose of 1250 mg of lapatinib and 3.2 mg/m2 of IV topotecan on days 1, 8 and 15. No DLT were seen during the dose escalation stage of cohorts IA and IB. Ten patients were enrolled at the MTD. There were no grade 4+ events. Thirteen grade 3+ events, considered to be related to treatment, were seen in 6 patients. The most common grade 3+ toxicities included dehydration (2) diarrhea (2), nausea (3), vomiting (2), neutropenia (1), thrombocytopenia (1), and fatigue (1). No abnormalities in left ventricular ejection fraction were noted. Stable disease was seen in 46% of the 37 patients. Conclusions: The combination of lapatinib and topotecan is a well-tolerated regimen. The MTD for the combination is lapatinib 1,250 mg orally once daily for 21 or 28 days and topotecan 3.2 mg/m2 on days 1, 8 and 15. Pharmacokinetic analysis for drug interaction will be available for presentation at the meeting. Supported in part by GSK and Mayo Clinic No significant financial relationships to disclose.

Abstract Purpose Preclinical and clinical data have shown promise in using antiangiogenic agents to treat malignant pleural mesothelioma (MPM). We conducted this phase II study to evaluate the efficacy and toxicity of single-agent pazopanib in patients with MPM. Materials and Methods Patients with MPM who had received 0–1 prior chemotherapy regimens were eligible to receive pazopanib at a dose of 800 mg daily. The primary endpoint was progression-free survival rate at 6 months (PFS6), with a preplanned interim analysis for futility. Secondary endpoints included overall survival (OS), PFS, adverse events assessment and clinical benefit (complete response, partial response [PR], and stable disease [SD]). Results Thirty-four evaluable patients were enrolled, with a median age of 73 years (49–84). The trial was closed early because of lack of efficacy at the preplanned interim analysis. Only 8 patients (28.6%; 95% confidence interval [CI], 13.2–48.7%) in the first 28 evaluable were progression-free at 6 months. PFS6 was 32.4% (95% CI, 17.4–50.5). There were 2 PR (5.9%) and 16 SD (47.1%). The overall median PFS and OS were 4.2 months (95% CI, 2.0–6.0) and 11.5 months (95% CI: 5.3–18.2), respectively. The median PFS and OS for the previously untreated patients was 5.4 months (95% CI, 2.7–8.5) and 16.6 months (95% CI, 6.6–30.6), respectively; and 2.0 months (95% CI, 1.3–4.2) and 5.0 months (95% CI: 3.0–11.9), respectively, for the previously treated patients. Grade 3 or higher adverse events were observed in 23 patients (67.6%). Conclusion Single-agent pazopanib was poorly tolerated in patients with MPM. The primary endpoint of PFS6 was not achieved in the current study. ClinicalTrials.gov identification number. NCT00459862. Implications for Practice Single-agent pazopanib did not meet its endpoint in this phase II trial in malignant mesothelioma. Pazopanib is well tolerated in mesothelioma patients with a manageable toxicity profile. There is a need to better identify signals of angiogenesis that can be targeted in mesothelioma. Encouraging findings in frontline treatment warrant further investigations in combination with chemotherapy or immunotherapy.

82 Background: Use of immune checkpoint inhibitors (ICI) in metastatic solid malignancies can occasionally result in a complete response (CR). There is limited long-term data regarding outcomes for patients who achieve a CR on ICIs. Methods: We screened the Mayo Clinic electronic medical record using an institutional database query program to identify patients whose records contained keywords such as “pembrolizumab” and “complete response” or “no evidence of disease.” Patients were included if they had measurable metastatic solid tumor disease prior to initiation of ICI and if they had a CR defined by two consecutive imaging studies at least twelve weeks apart. Exclusion criteria included oligometastatic disease treated with locoregional therapy or presence of a second confounding malignancy. Results: One-hundred four patients with a CR on pembrolizumab met criteria. Most (71.1%) patients had melanoma and 63/103 (61.2%) received had received the ICI during the first line of metastatic systemic therapy. Additional characteristics are in Table. At a median follow-up of 35.8 months (6.1-87.7), patients had received ICI for a median of 12.1 months (1.5-46.7). The vast majority of patients who stopped ICI did so electively (for reasons other than disease progression). Of 88 elective discontinuations, only 7 patients had disease recurrence after a median follow-up from start of ICI of 40.5 months. Conclusions: Patients with a metastatic solid malignancy who achieve a CR to pembrolizumab appear to maintain remissions off therapy, with low rates of relapse. Further outcomes will be explored, including analyzing and characterizing a sub-group of “hyper-responders” and patients receiving other ICI agents. [Table: see text]

Context.— Pulmonary carcinoids are classified as typical or atypical by assessing necrosis and mitoses, which usually cannot be adequately assessed on small biopsies. Ki-67 is not currently used to grade pulmonary carcinoids, but it may be helpful to determine preliminary grade in biopsies. However, the rate at which Ki-67 could underestimate or overestimate grade on small biopsies has not been well studied. Objective.— To compare Ki-67 labeling obtained on small biopsies to subsequent resection. Design.— Ki-67 was performed on paired biopsy and resection specimens from 55 patients. Slides were scanned using Aperio ScanScope. Labeling index was determined using automated hot spot and tumor tracing methods. Results.— The study included 41 typical and 14 atypical carcinoids. Atypical carcinoids were larger and had more distant metastases. Death from disease occurred in 3 patients (all had atypical carcinoids). Median hot spot Ki-67 labeling index was greater in resection compared with biopsy by 0.7% (P = .02). Median tumor tracing Ki-67 was lower in resection compared with biopsy by 0.5% (P < .001). Receiver-operating characteristic analysis showed similar hot spot Ki-67 cutoffs to predict atypical histology (3.5% for biopsy, 3.6% for resection; area under the curve [AUC], 0.75 and 0.74, respectively). Different optimal cutoffs were needed for tracing method based on biopsy (2.1%; AUC, 0.75) compared with resection (1.0%; AUC, 0.67). Conclusions.— Hot spot Ki-67 tends to underestimate grade on small biopsies, whereas grade is overestimated by tumor tracing. Hot spot Ki-67 cutoff of 3.5% predicted atypical histology for both biopsy and resection. Different biopsy and resection cutoffs were necessary for tumor tracing, which would make clinical implementation more difficult.

Introduction Despite more robust attempts to deliver chemotherapy in the outpatient setting, certain regimens for hematologic malignancies require inpatient hospitalization for treatment and monitoring clinical status. Increased length of stay (LOS) for planned chemotherapy admissions leads to increased healthcare utilization and decreased patient satisfaction. We sought to identify potentially modifiable risk factors for increased LOS. Methods Planned chemotherapy admissions to the inpatient hematology services at Mayo Clinic (Rochester, MN) from October 2018 through March 2019 were reviewed. We included patients who had treatment plans based on four pre-specified common regimens for acute myeloid leukemia, relapsed non-Hodgkins lymphoma and multiple myeloma. Patients who remained in the hospital for lack of caregiver support were excluded. Patient characteristics, including age, malignancy type, and chemotherapy regimen were recorded. Encounter characteristics included day of week of admission, time of admission, time chemotherapy plan initiated, and whether or not all necessary procedures (labs, vascular access, chemo orders) were completed prior to admission. Primary outcome was LOS. Secondary outcome was time to treatment initiation (TTI) after admission. Results There were 100 planned admissions for patients receiving four regimens: cytarabine consolidation, EPOCH, ICE, VDT-PACE, during the six month review period. Thirty-six admissions did not occur as planned (regimen changed, rescheduled, or disease progression). Of the remaining 66 admissions, 11 outliers were excluded from primary analysis. Baseline characteristics are summarized in Table 1. Univariate analysis with independent t-test found no difference in LOS for patients who had physician chemotherapy orders in place prior to admission. To the contrary, we detected a non-significant trend toward longer mean length of stay for patients that were not seen in clinic on day of admission (Table 2). On ANOVA, there was a statistically significant difference in LOS when comparing Monday admissions 3.93 days (95% CI 3.07 to 4.79) vs Friday 5.25 days (95% CI, 4.86 to 5.64), but not between any other days. There were no statistically significant differences in TTI when comparing by day of week, physician order status, or chemotherapy regimen. Again, a non-significant trend toward increased TTI was observed for patients not seen in clinic on the same day as admission. Conclusions This study serves as a starting point towards identifying modifiable factors that are essential to delivery of safe, satisfying inpatient care to our hematological malignancy patients.Our noteworthy finding regarding patients who were admitted on Friday having a longer LOS than those admitted on Monday requires further exploration. This study is ongoing with mature data to be presented at the meeting. Disclosures No relevant conflicts of interest to declare.

144 Background: Small cell lung cancer (SCLC) is highly responsive to cytotoxic therapy and can be cured in early stages of disease. In this setting, disparities in patient refusal despite provider recommendations are unknown. Methods: All incident limited stage (LS)-SCLC cases from the National Cancer Database were identified from 2004 to 2014. Logistic regression was used to determine factors associated with treatment refusal. Results: 65,664 patients (pts) were identified with LS-SCLC: 44% male, median age 68 years. 3.4% of pts refused radiation and 3.8% refused chemotherapy. The proportion of chemotherapy refusal increased over the study period: 3% in 2004-2006 compared to 5.4% in 2013-2014 [odds ratio (OR) 1.76, 95% confidence interval (CI) 1.55-2.01]; this was not observed for radiation. In multivariate analysis, women were more likely to refuse radiation (OR 1.18, 95% CI 1.06-1.32) and chemotherapy (OR 1.30, 95% CI 1.19-1.43) than men. Women who accepted treatment had higher overall survival compared to those who refused radiation (19.8 vs 5.2 months) or chemotherapy (17.4 vs 3.9 months) (both p < 0.001). Hispanic, Black, and Asian pts were not more likely to refuse treatment than White pts. Older pts were more likely to refuse radiation (OR 1.09 per year, 95% CI 1.08-1.09) and chemotherapy (OR 1.10 per year, 95% CI 1.09-1.11). Charlson comorbidity index (CCI) of 2 was associated with more frequent treatment refusal compared to CCI of 0 (radiation OR 1.96, 95% CI 1.68-2.30; chemotherapy OR 1.54, 95% CI 1.34-1.76). Medicaid as primary insurance predicted a higher risk of refusal compared to private insurance for radiation (OR 2.36, 95% CI 1.81-3.07) and chemotherapy (OR 2.23, 95% CI 1.78-2.80). Treatment at an academic facility predicted a lower risk of radiation refusal (OR 0.71, 95% CI 0.59-0.84) but not chemotherapy refusal. Conclusions: Female sex, comorbidities, and Medicaid insurance were predictors of treatment refusal in LS-SCLC, suggesting that socioeconomic and sex disparities may affect treatment decisions in this life-threatening disease. Further research to identify reasons for refusal via patient and provider interviews can improve care of vulnerable populations with potentially curable cancer.