A phase I/II study of LOAd703, a TMZ-CD40L/4-1BBL-armed oncolytic adenovirus, combined with nab-paclitaxel and gemcitabine in advanced pancreatic cancer

4138

Background: Due to its low tumor immunogenicity and immunosuppressive microenvironment, pancreatic ductal adenocarcinoma (PDAC) remains an immunotherapeutic challenge. LOAd703, an oncolytic adenovirus with transgenes encoding TMZ-CD40L and 4-1BBL, has been shown to lyse tumor cells selectively, induce anti-tumor cytotoxic T-cell responses, reduce myeloid-derived suppressor cell (MDSC) infiltration, and induce tumor regression in preclinical studies. Methods: In this phase I/II trial, patients with unresectable or metastatic PDAC were treated with intratumoral injections of LOAd703 and standard intravenous nab-paclitaxel/gemcitabine (nPG) chemotherapy. Starting on cycle 1 day 15 of nPG, LOAd703 was injected with image guidance into the primary pancreatic tumor or a metastasis every 2 weeks for 6 injections. In the event of sustained tumor control, subjects were eligible to receive up to 6 more injections. Three dose levels of LOAd703 were investigated using a BOIN dose escalation design. Primary endpoints were safety and feasibility. Results: Of the 22 subjects enrolled, 21 received at least 1 LOAd703 injection, and 18 received at least 3 LOAd703 injections (the a priori definitions of evaluability for dose limiting toxicity [DLT] and efficacy, respectively). Of the 21 subjects injected, median age was 61, 81% had stage IV disease, and 57% had already received chemotherapy for advanced disease. Median CA 19-9 was 1494. Of the 18 response evaluable subjects, 3 were treated at dose level 1 (5x10e10 VP), 4 at dose level 2 (1x10e11 VP), and 11 at dose level 3 (5x10e11 VP). The most common adverse events (AEs) attributable to LOAd703 were fever, chills, nausea, and increased liver enzymes. AEs were short-lived and grade 1/2, except for a grade 3 transaminase elevation in one subject receiving dose level 3 (the only DLT). Objective response rate (ORR) among those treated at the highest dose level was 55% (5/11 subjects), thus meeting the predefined criterion for efficacy. Among all response evaluable patients, overall response rate (ORR) was 44%, and disease control rate (DCR) was 94%. CA 19-9 decreased by ≥50% in 61% of evaluable patients. Median overall survival (OS) among the 21 subjects receiving at least 1 LOAd703 injection was 8.7 months. The proportion of T effector memory cells increased after initiation of on-protocol treatment (p = 0.0232) while the proportion of T regulatory cells and myeloid-derived suppressor cells decreased (p = 0.0410, p = 0.0256, respectively). Conclusions: Combining intratumoral injections of LOAd703 with standard nPG chemotherapy was safe and feasible. The target response rate at the highest dose level was met, and treatment-emergent immune responses were observed. A follow-up clinical trial combining LOAd703, nPG, and the anti-PDL-1 inhibitor atezolizumab is underway. Clinical trial information: NCT02705196.

Minimal residual disease assessment in colorectal cancer (MiRDA-C)

TPS236

Background: Detection of circulating tumor DNA (ctDNA) in the bloodstream is emerging as a novel marker for identifying of radiographically occult microscopic or minimal residual disease (MRD) in colorectal cancer (CRC) patients (pts) after curative intent treatments. Accumulating data suggest that ct-DNA defined MRD is a highly specific prognostic biomarker for future recurrences with a lead time of several months and prospective clinical trials are being conducted using ct-DNA defined MRD as an integral biomarker for improving risk stratification for adjuvant chemotherapy decision making. However, large scale, prospective data regarding kinetics of ctDNA-defined MRD with accurate pre-analytical methodology for plasma isolation and paired clinical data are limited. Methods: In this multi-center, prospective observational study, 1,000 pts with resectable CRC (stages II – IV) without other active malignancies undergoing therapy with curative intent will be enrolled any time from time of diagnosis up to start of adjuvant therapy (or ≤ 3 months post curative surgery, whichever is earlier). All therapeutic and surveillance visits decisions are at the discretion of the treating physicians. Serial biospecimens including blood (in Cell-Free DNA BCT tubes) to be processed to plasma and buffy coat in ≤ 2 days and formalin fixed tumor tissue will be collected at key time points until the time of radiographic recurrence or up to 5 years of surveillance. Blood draws will be at study entry, after each line of neoadjuvant therapy, post-surgery, during and after adjuvant therapy in addition to each surveillance visit. These blood draws will be coordinated with pts’ standard of care visits in order to minimize additional venipunctures. Relevant clinical data including demographics, cancer history, treatment details and outcomes, serum tumor markers and genomic data will be collected at each time point. Samples will be evaluated retrospectively with a primary objective of evaluating sensitivity and specificity of post-operative MRD for radiographic recurrences utilizing Guardant Health’s Reveal assay. Other key objectives include evaluating ctDNA kinetics with neoadjuvant and adjuvant therapies and to correlate with outcomes. The study is active, and enrollment is ongoing. Clinical trial information: NCT04739072.

A phase I trial targeting advanced or metastatic pancreatic cancer using a combination of standard chemotherapy and adoptively transferred nonengineered, multiantigen specific T cells in the first-line setting (TACTOPS)

4622

Background: Immunotherapy is emerging as a potent therapy for a range of hematologic malignancies and solid tumors. To target pancreatic carcinoma we have developed an autologous, non-engineered T cell therapy using T cell lines that simultaneously target the tumor-associated antigens (TAAs) PRAME, SSX2, MAGEA4, NY-ESO-1 and Survivin. These multiTAA-specific T-cell lines could be consistently prepared by culturing PBMCs in the presence of a Th1-polarizing/pro-proliferative cytokine cocktail, and adding autologous pepmix-loaded DCs as APCs. Methods: Patients with locally advanced or metastatic pancreatic adenocarcinoma who achieved cancer control with three months of standard chemotherapy were eligible to receive up to 6 infusions of multiTAA T-cells (fixed dose - 1x107 cells/m2). While also continuing the same chemotherapy, T-cells were given at monthly intervals from month four, onwards. The primary study endpoints were safety and feasibility of completing all 6 planned infusions, with secondary and tertiary endpoints including anti-tumor effects, patient survival, in vivo expansion and T cell persistence of the infused cells as well as recruitment of the endogenous immune system. Results: Between June 2018 and December 2019, we treated 13 patients with multiTAA T-cells. For 12/13 patients, we generated sufficient cells for all 6 planned doses; 2 doses were available for the remaining patient. Of the 13 patients, 8 maintained cancer control for a longer than expected duration, compared to historical controls. With administration of T-cells, 3 of these 8 patients had partial responses and 1 patient had a radiographic complete response (per RECIST). These responses were seen in patients with metastatic cancer. Notably, no patient had infusion-related systemic- or neuro-toxicity. Thus, infusion of autologous multiTAA-targeted T cells directed to PRAME, SSX2, MAGEA4, NY-ESO-1 and Survivin has been safe and provided durable clinical benefit to patients with pancreatic adenocarcinoma. Conclusions: Autologous, TAA cytotoxic T-cells can reliably be generated and safely administered to patients in conjunction with standard of care chemotherapy. In some patients, addition of T-cells may extend duration of first line therapy cancer control and induce additional tumor responses, and activation of the endogenous immune system has been documented in all patients. Exploration in a higher phase study is warranted. Clinical trial information: NCT03192462 .

A phase I/II study combining a TMZ-CD40L/4-1BBL-armed oncolytic adenovirus and nab-paclitaxel/gemcitabine chemotherapy in advanced pancreatic cancer: An interim report

716

Background: Pancreatic ductal adenocarcinoma (PDAC) has been highly resistant to immunotherapeutics to date. LOAd703, an oncolytic adenovirus with transgenes encoding TMZ-CD40L and 4-1BBL, has been shown to lyse tumor cells selectively, induce anti-tumor cytotoxic T-cell responses, reduce myeloid-derived suppressor cell (MDSC) infiltration, and induce tumor regression in preclinical studies. Methods: In this phase I/II trial, patients with unresectable or metastatic PDAC are treated with LOAd703 intratumoral injections and standard nab-paclitaxel/gemcitabine (nab-P/G) chemotherapy. Starting on cycle 1 day 15 of nab-P/G, LOAd703 is injected with image guidance into the primary pancreatic tumor or a metastasis every 2 weeks for 6 injections. In the event of sustained tumor control, subjects are eligible to receive 6 more injections. Three dose levels of LOAd703 are being investigated using a BOIN dose escalation design. Primary endpoints are safety and feasibility. Secondary endpoints include response rate and overall survival. Results: To date, 13 subjects are evaluable for safety and feasibility. Three patients were treated at dose 1 (5x10e10 VP), 4 subjects at dose 2 (1x10e11 VP), and 6 subjects at dose 3 (5x10e11 VP). The most common adverse events (AEs) attributed to LOAd703 have been fever, chills, nausea, and increased transaminases. AEs have been transient and grade 1-2, with the exception of a grade 3 transaminase elevation in 1 subject receiving dose 3 (the only dose-limiting toxicity observed thus far). During protocol treatment, circulating MDSCs decreased in 8/13 subjects while effector memory T-cells increased in 10/13. ELISPOT analyses showed a rise in tumor antigen-specific T-cells in 10/13 subjects. At the lowest dose level, best response was stable disease, and 6/10 patients who received higher LOAd703 doses have had partial responses. Only 1 patient has had progressive disease as best response. Conclusions: Adding LOAd703 to nab-P/G has been safe and feasible. Treatment-emergent immune responses have been demonstrated in most subjects, with a notable proportion having objective anti-tumor responses. Clinical trial information: NCT02705196.

Outcomes among minority patients with stage IV colorectal cancer in the Harris County Health System

e18039

Background: Colorectal cancer (CRC) mortality has declined over the last three decades, but significant racial disparities in CRC survival continue to be reported, especially for stage IV disease. Hypothesizing that these disparities arise from differences in access to care rather than tumor biology, we examined treatment patterns and outcomes among minority patients evaluated and treated for stage IV CRC in an academic safety net health system. Methods: The Harris Health System is an integrated health delivery network that utilizes tax revenue to care for predominantly minority and uninsured residents of Harris County, Texas. As the largest Harris Health facility and an affiliate of the Dan L. Duncan Comprehensive Cancer Center at Baylor College of Medicine, Ben Taub Hospital delivers cancer care through multidisciplinary subspecialty clinics and a robust patient assistance program. We performed a retrospective analysis of minority patients diagnosed with stage IV CRC between 1/2010 and 12/2012 who were evaluated and treated at Ben Taub Hospital. Results: We identified 103 patients of whom 40% were black, 49% were Hispanic, and 12% were Asian or Middle Eastern. 65% spoke English as their preferred language; 74% were uninsured and covered by the Harris Health Plan, a financial assistance program for individuals with incomes under 300% of the federal poverty level. 85% of patients received cancer-directed therapy, of whom 99% received standard chemotherapy with a best response rate of 67% and a disease control rate of 87%. Median overall survival was 20.7 months for all patients and 23.0 months for patients who received chemotherapy. Conclusions: The Harris Health System provides the health delivery infrastructure through which minority patients with significant socioeconomic challenges obtain financial assistance and access to quality cancer care in an academic setting, thereby leading to clinical outcomes comparable to those of the predominantly Caucasian and insured populations studied in randomized control trials. Efforts to resolve disparities in CRC outcomes should focus on improving access of at-risk populations to comprehensive cancer care.

Identification of educational gaps among oncologists who treat patients with pancreatic cancer

431

Background: Pancreatic ductal adenocarcinoma (PDA) is the fourth-most common cause of cancer-related death in the United States, with only 7.7% of patients surviving beyond 5 years. Given the poor outcomes associated with PDA, it is imperative that patients with PDA receive optimal care. Continuing medical education (CME) offers an effective means to improve physician performance, and CME programs are most effective when they address areas of greatest need. This study was conducted to identify and quantify the educational gaps in PDA management that can potentially be addressed with CME. Methods: A case-vignette survey instrument was developed to assess physicians’ practices related to PDA. Case vignettes are a validated means of assessing healthcare provider practice patterns. The survey instrument included three patient cases: 1) A 50 year-old man with resectable PDA; 2) a 75 year-old man with locally advanced, unresectable PDA; and 3) a 55 year-old woman with metastatic PDA. Each case was followed by a series of questions designed to assess medical decision-making, physician/patient communication, and barriers to optimal practice. Results: Survey responses were collected from 150 US oncologists in July 2016 (19% at academic centers). Several key educational gaps were identified. For Case 1, 44% of oncologists did not select an evidence-based adjuvant chemotherapy regimen from a list of options. For Case 2, in which the patient had developed metastases and neuropathy after first-line therapy, 57% of respondents did not select an evidence-based second-line option, and 35% selected a regimen with oxaliplatin. For Case 3, only 18% of oncologists recommended an initial diagnostic evaluation that included a biopsy, chest imaging, and liver function tests. Finally, for all 3 cases, little emphasis was placed on enrolling patients in clinical trials. Conclusions: This study identified appreciable discrepancies between respondents’ recommendations and standard evidence-based guidelines for treating all stages of PDA. Well-designed CME programs may help bridge the educational gaps among practicing oncologists and ultimately improve adherence to national guidelines.

Trends in multimodality therapy for gastric cancer post-MAGIC

148

Background: Althoughmultimodality therapy (MMT) is recommended for most patients with resectable gastric cancer, no single approach has been established as standard. As such, little is known about current national practice patterns and MMT treatment sequencing for patients with gastric cancer. Methods: This was a retrospective cohort study of ≥ T2 and/or node positive gastric cancer patients treated with MMT using the National Cancer Database (2006-2012). Patients were categorized based on type of MMT (chemotherapy, concurrent chemoradiation (cXRT), or both chemotherapy and cXRT) and treatment sequence (preoperative, postoperative, or perioperative). Accuracy of pre-treatment clinical nodal staging was ascertained by comparison to pathologic nodal staging in patients treated with upfront surgery. Multivariable Cox regression was used to evaluate the association between overall risk of death and MMT type and sequence. Results: Among 4,857 patients, 14.1% were treated perioperatively, 48.0% preoperatively, and 37.9% postoperatively. Rates of chemotherapy, cXRT, and both chemotherapy and cXRT were 32.1%, 53.4%, and 14.5%. Among patients treated with upfront surgery, sensitivity, specificity, PPV, and NPV of clinical nodal staging were 70.7%, 88.8%, 92.1%, and 62.2%, respectively. Over the study period, use of cXRT decreased (61.8% 2006 vs 52.0% 2012; trend test, p < 0.001) while use of chemotherapy increased (23.6% vs 35.7%; trend test, p < 0.001) and use of both chemotherapy and cXRT did not change. There was an increase in the use of perioperative treatment (8.1% vs 17.4%; trend test, p < 0.001) while postoperative treatment decreased (44.4% vs 31.1%; trend test, p < 0.001). After multivariable modeling, neither type of MMT nor treatment sequence was associated with risk of death. Conclusions: Although current national practice patterns favor pre- and perioperative treatment, one third of patients were treated with upfront surgery. Survival was not associated with MMT type or sequence. However, given the high false negative rate of clinical nodal staging and high non-completion rate of postoperative treatment (50% in MAGIC trial), efforts to improve gastric cancer outcomes should focus on increasing use of preoperative therapy.

Pathologic nodal response in gastric cancer: Do all patients need adjuvant therapy?

107

Background: Recent data from the MAGIC trial show that pathologically positive lymph nodes (ypN+) despite neoadjuvant (NA) chemotherapy are associated with poorer survival. Although the use of NA therapy has increased, pathologic disease response to multimodality therapy (MMT) and its impact on outcome have not been well-defined. Methods: This retrospective cohort study of the National Cancer Database included patients with cN+ gastric cancer who underwent NA therapy followed by surgical resection between 2006 and 2012. Patients were categorized by NA treatment (chemotherapy or concurrent chemoradiation). Pre-treatment clinical (cN) and pathologic nodal staging (ypN) were used to determine downstaging rates from cN+ to ypN0. The association between overall risk of death and NA treatment, nodal response, and the use of adjuvant therapy was evaluated with multivariable Cox regression. Results: Among 1,489 patients with cN+ gastric cancer receiving NA therapy, 45.5% were treated with chemotherapy and 54.5% with chemoradiation. Rates of nodal downstaging were 29.9% for chemotherapy and 45.4% for chemoradiation. On multivariable analysis, treatment sequence and type were not associated with risk of death. Median survival was significantly lower in patients with ypN+ compared to those with ypN0 disease (27.7 vs 79.7 months; log-rank, p < 0.001).Among patients with ypN+ disease (n = 918), median survival was greater if adjuvant therapy was received (32.6 months vs. 25.3 months, log-rank, p < 0.001); adjuvant therapy was associated with a 19% decreased risk of death (Hazard Ratio [HR] 0.81; 95% CI 0.66-0.99), with further reduction among those who underwent a margin negative resection (HR 0.73; 95% CI 0.58-0.92). In patients with ypN0, adjuvant therapy was not associated with a lower risk of death. Conclusions: Over one third of node-positive gastric cancers demonstrated pathologic nodal downstaging with NA treatment, with chemoradiation yielding a higher response than chemotherapy. Patients with ypN+ had worse survival, and appeared to benefit from adjuvant therapy. Future gastric cancer trials should better define the role for NA chemoradiation and help individualize the use of adjuvant therapy based on nodal response.