McWilliams, Robert R.

Abstract Purpose: Small-bowel adenocarcinoma (SBA) is rare, and no standard of care exists for metastatic disease beyond first-line FOLFOX/CAPOX. SBA has higher rates of microsatellite instability (MSI-H) and T-lymphocyte infiltration than other gastrointestinal cancers. We hypothesize that pembrolizumab, a PD-1 inhibitor, will induce antitumor response. Patients and Methods: Patients with previously treated advanced SBA received pembrolizumab 200 mg i.v. every 3 weeks until disease progression (PD), toxicity, or 35 doses maximum. Primary endpoint was confirmed overall response rate (ORR) with secondary progression-free survival (PFS), overall survival (OS), and toxicity assessment endpoints. Outcomes were stratified by tumor location, microsatellite stability (MSS) or instability (MSI-H), and PD-L1 level. Results: Forty patients were treated for a median duration of four cycles (range, 1–35). All patients are off study treatment due to PD (75%), death (10%), 35 cycles completed (8%), refusal (3%), and adverse effects (AEs, 5%). Three confirmed partial responses [PRs; 8%; 95% confidence interval (CI), 2–20] did not meet predefined success criteria of ORR 30%. Median OS (7.1 months; 95% CI, 5.1–17.1) and median PFS (2.8 months; 95% CI, 2.7–4.2) were similar across primary tumor sites. One confirmed PR (3%) was seen in patients with low MSS/MSI tumors and correlated with high tumor mutation burden (TMB). Fifty percent of patients with MSI-H tumors achieved PR and remain alive without progression. Twenty-five patients (63%) had grade ≥3 AEs and 11 patients (28%) had grade 4/5 AEs. Conclusions: In the largest study of SBA to date, pembrolizumab did not induce the hypothesized response rate; however, we did identify responses in key biomarker-selected cohorts.

Abstract Abstract Importance: The benefit of routine screening for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in patients with cancer before cancer-directed therapies is unclear. Herein, we characterize the outcomes of a cohort of cancer patients diagnosed with Coronavirus Disease 2019 (COVID-19) by routine screening in comparison with those diagnosed based on clinical suspicion or exposure history (non-routine screening). Objective: To describe and compare the outcomes of cancer patients diagnosed with COVID-19 on routine screening vs. non-routine screening at a multi-site tertiary cancer center. To identify risk factors for COVID-19-related hospital admission. Design: A multi-site prospective observational study was conducted between March 18 and July 31, 2020. Setting: Three major and 5 satellite campuses of the Mayo Clinic Cancer Center. Participants: Adult patients diagnosed with active cancer within the past five years and confirmed SARS-CoV-2 infection were included. Primary Outcomes and Measures: Clinical and laboratory data were assessed as independent variables. The primary outcome was COVID-19-related hospital admission. Secondary outcomes included intensive care unit (ICU) admissions and all-cause mortality. Results: Between March 18 and July 31, 2020, 5452 patients underwent routine screening in the outpatient setting, 44 (0.81%) were diagnosed with COVID-19. Routine screening detected additional 19 patients from inpatient and pre-procedural settings; 161 patients were diagnosed with COVID-19 based on non-routine screening. The median age of the entire cohort at diagnosis was 54 years, and 95 patients (42.2%) were female. COVID-19 related-hospitalization rate (17.5% vs. 26.7%, p=0.14), ICU admission (1.6% vs. 5.6%, p=0.19), and mortality (4.8% vs. 3.7%, p=0.72) were not significantly different between routine screening and non-routine screening groups. In the multivariable analysis, age ≥ 60 years (odds ratio: 4.4, p=0.023) and an absolute lymphocyte count ≤1.4 × 109/L (odds ratio: 9.2, p=0.002) were independent predictors of COVID-19-related hospital admission. Conclusions and Relevance: The COVID-19 positivity rate was low based on routine screening. Comparing the outcome with the non-routine screening cohort, there was no significant difference. These results led to an important practice change at our cancer center. We currently follow a testing strategy based on symptoms, exposure, risk factors, and clinical judgment. Citation Format: Zhuoer Xie, Antoine N. Saliba, Jithma Abeykoon, Umair Majeed, Daniel Almquist, Julia Wiedmeier-Nutor, Evandro Bezerra, Xavier Andrade-Gonzalez, Ashley Hickman, Karl Sorenson, Sagar Rakshit, Christopher Wee, Sri Tella, Anuhya Kommalapati, Nadine Abdallah, Joshua Pritchett, Mariza De Andrade, Dipesh Uprety, Andrew Badley, Joleen Hubbard, Naseema Gangat, Carrie A. Thompson, Thomas Witzig, Robert R. McWilliams, Konstantinos Leventakos, Thorvardur R. Halfdanarson. Outcomes of COVID-19 in patients with cancer: Results of a prospective observational comparison of routine screening strategy versus testing based on clinical suspicion [abstract]. In: Proceedings of the AACR Virtual Meeting: COVID-19 and Cancer; 2021 Feb 3-5. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(6_Suppl):Abstract nr S06-03.

239 Background: After trastuzumab (T) approval for advanced HER2-positive E/GEJ-AC, HER2 testing has increased in patients (pts) with resectable disease. Neoadjuvant carboplatin/paclitaxel chemoradiation (nCP-CRT) is a common therapy approach. We performed the largest evaluation, to our knowledge, of the prognostic impact of HER2 in E/GEJ-AC pts treated with nCP-CRT. Methods: We retrospectively reviewed medical records of all trimodality-eligible (T2+ or N+) pts with E/GEJ-AC who started nCP-CRT (usually 50.4 Gy) with planned surgery at Mayo Clinic (2014-2019). HER2 was tested using standard criteria for HER2 positivity (ie, immunohistochemistry 3+ or amplification by in situ hybridization). Clinicopathologic data and time to recurrence (TTR), disease free survival (DFS), overall survival (OS), survival after recurrence (SAR), and pathologic complete response (pCR – ie, no residual tumor in primary or nodes) were collected. Kaplan Meier and multivariate Cox analysis were used. Results: Of 161 consecutive eligible pts, HER2 status was available in 107 pts (HER2-positive n=26, HER2-negative n=81) of whom n=82 had surgery and n=19 had pCR. Most tumors were clinical T3 (80%) or N+ (81%), histologic grade 3 of 3 (62%). HER2 positivity was significantly associated with lower grade, but not with age, clinical T or N, or ECOG performance status (PS). A similar proportion of HER2-positive ( vs negative) pts had surgery. Among pts who had surgery, pCR rates were lower in HER2-positive ( vs negative) pts (11% [2/19] vs 27% [17/63]). After a median follow up of 23 mo, DFS and TTR were significantly shorter in HER2 positive ( vs negative) pts, independent of other pretreatment covariables (Table). Yet OS was comparable. Lung recurrence was enriched in HER2 positive ( vs negative) pts. Among pts with recurrence, SAR was longer in HER2-positive vs -negative pts. A total of 53% (10/19) of previously HER2-positive pts received T-based therapy after recurrence, and these pts were the drivers of favorable SAR (median 22 mo in n=10 HER2-positive pts who received T vs 11 mo in n=9 HER2-positive pts who did not receive T vs 11 mo in n=40 HER2-negative pts; P log-rank=.01). Conclusions: HER2 positivity ( vs negativity) is independently associated with shorter TTR and DFS, but more comparable OS. The adverse association of HER2 on tumor response and TTR may have been largely overcome through enhanced survival after recurrence, although OS data are maturing. These data may have implications for the design of endpoints in future curative-intent anti-HER2 trials. [Table: see text]

Abstract Purpose: To compare the clinical characteristics and overall survival (OS) of germline mutation carriers in homologous recombination repair (HRR) genes and noncarriers with pancreatic ductal adenocarcinoma (PDAC). Experimental Design: Germline DNA from 3,078 patients with PDAC enrolled in a prospective registry at Mayo Clinic between 2000 and 2017 was analyzed for mutations in 37 cancer predisposition genes. Characteristics and OS of patients with mutations in eight genes (ATM, BARD1, BRCA1, BRCA2, BRIP1, PALB2, RAD51C, and RAD51D) involved in HRR were compared with patients testing negative for mutations in all 37 genes. Results: The 175 HRR mutation carriers and 2,730 noncarriers in the study had a median duration of follow-up of 9.9 years. HRR mutation carriers were younger (median age at diagnosis: 63 vs. 66 years, P < 0.001) and more likely to have metastatic disease at diagnosis (46% vs. 36%, P = 0.004). In a multivariable model adjusting for sex, age at diagnosis, and tumor staging, patients with germline HRR mutations had a significantly longer OS compared with noncarriers [HR, 0.83; 95% confidence interval (CI), 0.70–0.97; P = 0.02]. Further gene-level analysis demonstrated that germline ATM mutation carriers had longer OS compared with patients without germline mutations in any of the 37 genes (HR, 0.72; 95% CI, 0.55–0.94; P = 0.01). Conclusions: This study demonstrates that germline mutation carrier status in PDAC is associated with longer OS compared with noncarriers. Further research into tumor biology and response to platinum-based chemotherapy in germline mutation carriers with PDAC are needed to better understand the association with longer OS.

Abstract Background: Focal adhesion kinase (FAK) is consistently hyperactivated in multiple tumor types including PDAC. Our preclinical work showed that FAK and PD-1 inhibitors elicit significant tumor regression, and that combining FAK and PD-1 inhibitors with gemcitabine achieves a maximal response. This suggests the need for a cytotoxic agent to bolster antigen presentation. Defactinib is an orally available, well-tolerated, potent FAK inhibitor. Methods: This study included a dose escalation phase (all solid tumors) and dose expansion phase (metastatic PDAC). A 3+3 design with five dose levels was used in the dose escalation phase. For the expansion phase, 10 PDAC patients with stable disease on front-line gemcitabine/nab-paclitaxel were enrolled in the Maintenance cohort (A), while 10 patients who progressed on at least one line of therapy were enrolled in the Refractory cohort (B). Pre and on-treatment biopsied were collected from all PDAC patients. The primary endpoint was to determine the recommended phase 2 dose (RP2D). Secondary endpoints included safety, toxicity, objective response rate, progression-free survival (PFS) and overall survival (OS). The exploratory endpoints included developing a molecular and immune profile for treatment response. Results: In dose escalation, the common low grade (G1/2) treatment-emergent adverse events included fatigue, anorexia, nausea and vomiting. No DLTs were seen. The RP2D was defactinib 400mg twice daily, gemcitabine 1000 mg/m2 days 1, 8 and pembrolizumab 200mg day 1 of a 21-day cycle. Safety and toxicity results in the escalation cohort were reported at the 2018 ASCO Annual Meeting. Among 8 evaluable PDAC patients enrolled on the dose escalation phase, we observed 1 (13%) partial response (PR), 3 (38%) stable disease (SD), 4 (50%) progressive disease (PD). In the Maintenance cohort, 1 (10%) PR, 6 (60%) SD, and 3 (30%) PD were observed. Two patients in the Maintenance cohort remain on study, and the median time on treatment was 4.6 months. In the Refractory cohort, 5 (50%) had SD, 4 (40%) PD, 1 not evaluable; median PFS was 2.9 months and median OS was 7.6 months. Interestingly, two confirmed PR patients both have MSS disease. Paired biopsies in PDAC patients show increased proliferating CD8+ T cells, while Tregs, macrophages, and stromal density decrease with treatment. Conclusions: The combination regimen was well tolerated. Encouraging efficacy signals were observed in both Maintenance and Refractory cohorts. Updated outcomes and correlative analyses are forthcoming. Citation Format: Andrea Wang-Gillam, Robert McWilliams, A. Craig Lockhart, Benjamin R Tan, Rama Suresh, Kian-Huat Lim, Katrina S. Pedersen, Nikolaos Trikalinos, Olivia Aranha, Haeseong Park, Lee Ratner, Nicholas Boice, David G. Denardo. Phase I study of defactinib combined with pembrolizumab and gemcitabine in patients with advanced cancer: Experiences of pancreatic ductal adenocarcinoma (PDAC) patients [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 CT118.

Abstract Immunotherapy targeting immune checkpoints has become a common approach for many types of cancer but currently there are no reliable biomarkers to predict and monitor treatment response. Immunohistochemical staining of PD-L1, which was initially developed as a companion diagnostic, is problematic due to tumor heterogeneity, variations in specimen preparation and multiple scoring schemes. There is, therefore, a critical need for a better biomarker to guide the use of immunotherapy to improve clinical outcomes. We previously reported that higher levels of Bim and CX3CR1/granzyme B in CD8+ T cells were associated with increased response to PD-1 blockade therapy in patients with melanoma; high levels of Bim were also prognostic of poor survival in melanoma patients. In this study, we investigated the roles of Bim and CX3CR1/granzyme B in patients receiving PD-1 blockade therapy (i.e. pembrolizumab) for small bowel adenocarcinoma as part of planned correlative analysis of the ACCRU clinical trial, NCT02949219. Patients with unresectable or metastatic biopsy-proven small bowel adenocarcinoma (excluding ampulla of Vater and appendix) who had at least one prior line of systemic chemotherapy were eligible for the trial. Pembrolizumab (200 mg) was administered over 30 minutes intravenously every 3 weeks until unacceptable toxicity, disease progression, or patient refusal. All patients underwent peripheral blood collection at baseline prior to initiation of treatment and then after 3 cycles of treatment. Levels of Bim and CX3CR1/granzyme B in circulating T cells were quantified by flow cytometry using patients' peripheral blood mononuclear cells. Data was analyzed via Cox proportional hazards model, Wilcoxon Rank-Sum test, and Kaplan Meier curves using SAS 9.4. A total of 35 eligible patients were included in the analysis. Three patients had confirmed response (all partial responses) and 10 had stable disease as their best overall response. Seven patients had disease progression around the second blood draw. The median time from baseline to the second blood draw was 9 weeks. Lower levels of Bim in CD8+CD11ahi T cells at baseline on the percentage scale were associated with treatment response (median 54.5% vs. 79.5%; p=0.0087) and disease control (partial response plus stable disease; median 71.2% vs. 81.3%; p=0.0104) but higher levels led to worse progression-free survival (hazard ratio=1.05, 95% confidence interval 1.01-1.08; p=0.0051). In addition, positive changes in CX3CR1/granzyme B in CD8+CD11ahi T cells from baseline were associated with better overall survival (median 20.2 months vs. 3.7 months, p=0.0086). The levels of PD-1 and Ki-67 in CD8+CD11ahi T cells were not associated with treatment response or survival. In conclusion, Bim and CX3CR1/granzyme B are biomarkers that associate with response and survival benefits respectively of PD-1 blockade therapy. This preliminary data calls for a larger-scale, prospective study to validate their predictive and prognostic utilities. Citation Format: Mojun Zhu, Henan Zhang, Nathan R. Foster, Haidong Dong, Tanios S. Bekaii-Saab, Brandy L. Jaszewski, Patrick M. Boland, Michael J. Overman, Katrina Pedersen, Robert R. McWilliams, Academic and Community Cancer Research United (AACRU). Bim and CX3CR1/granzyme B in circulating CD8+ T cells are predictive biomarkers for PD-1 blockade therapy [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 4467.

9055 Background: There is increasing evidence that paclitaxel and carboplatin are clinically active in the treatment of metastatic melanoma (MM). Nab-P is an albumin-bound paclitaxel with ability to bind SPARC (secreted protein acid rich in cysteine), that is overexpressed in MM and associated with poor prognosis. This study explores the clinical activity of the combination of nab-P and C in patients (pts) with stage IV melanoma and SPARC correlatives. Methods: A parallel phase II trial was conducted in pts with unresectable stage IV melanoma, who were either chemotherapy naïve (CN) or were previously treated (PT). A treatment regimen consisting of nab-P (100 mg/m2) and C (AUC 2) was administered on days 1, 8, and 15 of a 28 day cycle. The primary aim of this study was to assess whether tumor response rate (CR + PR by RECIST) was ≤15% vs ≥35% in the CN group and ≤5% vs ≥ 20% in the PT cohort. Major eligibility criteria: ≥18 years of age, ECOG PS ≤2, adequate organ function, platinum or taxane naive, peripheral neuropathy < grade 2, and no untreated brain metastasis; no pregnant and/or nursing women. Tumor tissue was tested for SPARC and level 3 immunohistochemical staining was considered positive. Results: 76 pts (41-CN and 35 PT) enrolled from 11/2006 - 7/2007, 3 pts (2-CN, 1-PT) cancelled prior to starting treatment. The median number of cycles administered was 4 (range 1–18-CN and 1–10-PT). There were 11 (28.2%) confirmed responses (1 CR and 10 PRs) in the CN cohort (90% CI: 16.7–42.3%) and 3 (8.8%) confirmed responses (3 PRs) in the PT cohort (90% CI: 2.5–21.3%). Median PFS was 4.5 months (CN) and 4.1 months (PT). Median OS was 11.1 months (CN) and 10.9 months (PT).The most common severe toxicities in both groups (CTCAE ≥ grade 3) included neutropenia, thrombocytopenia, neuro-sensory, fatigue, nausea, and vomiting. PFS was not affected by SPARC positivity; however, based on limited data there is some evidence that OS may be longer with tumoral SPARC positivity (10.0 vs 12.8 mo; SPARC negative vs SPARC positive). Conclusions: The weekly combination of nab-P and C appears to be well tolerated with promising clinical activity as front line or salvage therapy in pts with MM. SPARC positivity may be associated with improved OS. No significant financial relationships to disclose.

e20013 Background: Recent evidence suggests that patients with advanced cancer exhibit an underlying anti-tumor immune response that is continuously attenuated by regulatory T cells (Treg). Depletion of Treg using conventional chemotherapy may be feasible and clinically beneficial. C-reactive protein (CRP) is reported to rise/fall with initiation/termination of the immune response, and may be a surrogate for the periodicity of Treg proliferation that could be utilized for timing of anti-proliferative therapy. Timed delivery of chemotherapy therapy based on CRP cycling may deplete Treg and yield clinical benefit. Methods: We conducted a pilot clinical for 12 patients with metastatic melanoma who underwent serial CRP measurements (every 2–3 days) for 2 weeks. The CRP oscillation cycle was identified and chemotherapy with temozolomide (200mg/m2 for 5 days, every 28 days) was initiated at the estimated peak of plasma CRP. Patients were evaluated for clinical and immune response endpoints every 8 weeks until progression. Results: All 12 patients (median age 61; 4 female; 7 with M1c disease) exhibited oscillating CRP levels with an average periodicity of 7.8 days. Only 11 patients were treated (1 patient had rapid tumor progression). The two patients who remain progression-free for >2 years (1 PR, 1 CR), were treated in the pre-peak section of the CRP cycle, distinctly separate from the other patients treated post CRP-peak (all progressed <5 months). Presented are peripheral blood immunological laboratory correlates (cellular and cytokine) to CRP oscillation. Conclusions: These data suggest that patient clinical outcome may be dependent on the timing of therapy relative to an individual patient's immune response cycle and outline the dynamic equilibrium of systemic immune homeostasis in patients with advanced melanoma. Further investigations of these observations are under way. [Table: see text]