Bekaii‐Saab, Tanios

Abstract Background Hand-foot skin reaction (HFSR) is the most common regorafenib-induced adverse event and is in need of effective prevention and palliation. Materials and Methods The Regorafenib Dose Optimization Study (ReDOS), a four-arm, previously published trial with a 1:1:1:1 randomization scheme, was analyzed in a manner in keeping with the original protocol to assess whether clobetasol 0.05% cream (a corticosteroid) applied to the palms and soles twice per day for 8 weeks was more effective when prescribed preemptively (before the development of HFSR) versus reactively (after the development of HFSR). Patients were assessed during the first two cycles of regorafenib. Results Sixty-one patients received preemptive clobetasol, and 55 received reactive clobetasol. Groups were balanced on demographics. Over the first two cycles, no evidence of HFSR occurred in 30% with preemptive clobetasol versus 13% with reactive clobetasol (p = .03). During the first cycle, 54% and 45% of patients had no HFSR with preemptive and reactive clobetasol, respectively (p = .35). During the second cycle, 33% and 15% had no HFSR with preemptive and reactive clobetasol, respectively (p = .02). During the second cycle, rates of grade 1, 2, and 3 HFSR were 30%, 8%, and 3%, respectively, with preemptive clobetasol and 43%, 18%, and 7%, respectively, with reactive clobetasol (p = .12). Patient-reported outcomes showed HFSR compromised nearly all activities of daily living with worse quality of life in patients who received reactive versus preemptive clobetasol. No clobetasol-induced adverse events were reported. Conclusion Preemptive clobetasol might lessen regorafenib-induced hand-foot reactions compared with reactive therapy. Further confirmatory studies are needed in a larger patient cohort. Implications for Practice Regorafenib causes hand-foot skin reactions. Preemptive clobetasol, a high-potency topical corticosteroid, appears to lessen the severity of this adverse event. Although further study is needed, the favorable adverse event profile of this intervention might prompt clinicians to discuss this option with their patients.

Abstract Purpose Recent advances in molecular diagnostic technologies allow for the evaluation of solid tumor malignancies through noninvasive blood sampling, including circulating tumor DNA profiling (ctDNA). Pancreatic ductal adenocarcinoma (PDAC) has a poor prognosis, often because of late presentation of disease. Diagnosis is often made using endoscopic ultrasound or endoscopic retrograde cholangiopancreatography, which often does not yield enough tissue for next-generation sequencing. With this study, we sought to characterize the ctDNA genomic alteration landscape in patients with advanced PDAC with a focus on actionable findings. Materials and Methods From December 2014 through October 2019, 357 samples collected from 282 patients with PDAC at Mayo Clinic underwent ctDNA testing using a clinically available assay. The majority of samples were tested using the 73-gene panel which includes somatic genomic targets, including complete or critical exon coverage in 30 and 40 genes, respectively, and in some, amplifications, fusions, and indels. Clinical data and outcome variables were available for 165 patients; with 104 patients at initial presentation. Results All patients included in this study had locally advanced or metastatic PDAC. Samples having at least one alteration, when variants of unknown significance (VUS) were excluded, numbered 266 (75%). After excluding VUS, therapeutically relevant alterations were observed in 170 (48%) of the total 357 cohort, including KRAS (G12C), EGFR, ATM, MYC, BRCA, PIK3CA, and BRAF mutations. KRAS, SMAD, CCND2, or TP53 alterations were seen in higher frequency in patients with advanced disease. Conclusion Our study is the largest cohort to date that demonstrates the feasibility of ctDNA testing in PDAC. We provide a benchmark landscape upon which the field can continue to grow. Future applications may include use of ctDNA to guide treatment and serial monitoring of ctDNA during disease course to identify novel therapeutic targets for improved prognosis. Implications for Practice Pancreatic ductal adenocarcinoma (PDAC) has a poor prognosis often due to late presentation of disease. Biopsy tissue sampling is invasive and samples are often inadequate, requiring repeated invasive procedures and delays in treatment. Noninvasive methods to identify PDAC early in its course may improve prognosis in PDAC. Using ctDNA, targetable genes can be identified and used for treatment.

TPS252 Background: Tucatinib (TUC), a highly selective HER2-directed TKI recently approved for HER2+ metastatic breast cancer (MBC), is being developed as a novel therapy for patients (pts) with metastatic colorectal cancer (mCRC) and other GI tumors. While trastuzumab (Tras) with chemotherapy is standard in the 1st-line setting for metastatic HER2+ gastric or gastroesophageal junction adenocarcinoma (GEC), no anti-HER2 therapy has demonstrated an OS benefit over chemotherapy in 2nd-line, possibly due to loss of HER2 expression following Tras-based therapy. In GEC xenograft models, dual targeting of HER2 with TUC and Tras showed superior activity to either agent alone. Interim results from the MOUNTAINEER study have shown promising activity for TUC and Tras in HER2+ mCRC. The MOUNTAINEER-02 study is evaluating the efficacy and safety of TUC in combination with Tras, ramucirumab (Ram), and paclitaxel (Pac) in pts with HER2+ GEC. Methods: MOUNTAINEER-02 (NCT04499924) is a phase 2/3 study evaluating TUC and Tras with the 2nd-line standard of care, Ram and Pac. Pts receive TUC 300 mg or placebo PO BID, Tras (6 then 4 mg/kg) or placebo (IV on Days 1 and 15 of each 28-day cycle), Pac (IV on Days 1, 8, 15), and Ram (IV on Days 1 and 15). Eligible pts have locally-advanced unresectable or metastatic HER2+ GEC, have received a HER2-directed antibody, and 1 prior line of therapy for advanced disease. Pts must be ≥18 years of age, with an ECOG ≤1, and have had no prior exposure to Ram, anti-HER2 or anti-EGFR TKI, HER2-directed antibody-drug conjugates, or taxanes ≤12 months before enrollment. Due to the potential impact of TUC on Pac metabolism, the study will include an initial Pac dose finding stage. The open-label phase 2 part will determine the recommended dose of Pac (60 or 80 mg/m²) combined with TUC, Tras, and Ram in 6-12 patients, and evaluate the safety and activity of the regimen in Cohorts 2A and 2B (30 patients each). The randomized, double-blind, phase 3 part will compare the efficacy and safety of TUC and Tras (Arm 3A; ~235 patients) vs. placebo (Arm 3B; ~235 patients), both in combination with Ram and Pac, and also evaluate activity of TUC with Ram and Pac (Arm 3C; ~30 patients). The dual primary phase 3 endpoints are OS and PFS per investigator, with confirmed ORR as a key secondary endpoint. HER2 status is determined at baseline using a blood-based NGS assay, and IHC/ISH of fresh or archival tumor biopsies, if available. Pts must be HER2+ by blood-based NGS in Cohort 2A and phase 3; in Cohort 2B, pts must be HER2+ in a biopsy taken post-progression during/after 1st-line therapy, but HER2-negative by blood-based NGS. Disease assessments per RECISTv1.1 will occur q6 weeks for 36 weeks, then q9 weeks. The pharmacokinetics of TUC, Pac, and their metabolites will be evaluated in a subset of pts, including a cohort with gastrectomies. Enrollment is ongoing in the U.S. Clinical trial information: NCT04499924.

TPS155 Background: Chemotherapy in combination with targeted agents are standard-of-care options for patients for mCRC with response rates > 50% in first line. In the second line setting, efficacy of chemotherapy and targeted agents are much lower with response rates of 5% for FOLFIRI (5-fluorouracil, leucovorin, irinotecan) + bevacizumab (anti-VEGF). New treatment options are urgently needed in particular for the 50 % of patients harboring a KRAS mutation. PLK1 is a serine/threonine kinase, master regulator of the mitotic checkpoint and cell division. PLK1 is overexpressed in CRC and its overexpression is associated with poor prognostic. A genome wide RNAi screen identified PLK1 as a synthetic lethal target in KRAS mutant CRC cells, inducing cell cycle arrest and apoptosis upon inhibition. Onvansertib is an oral, highly selective PLK1 inhibitor that demonstrates single agent and synergistic activity with irinotecan and 5-FU in preclinical CRC models. Additionally, KRAS mutated versus wild-type cells showed higher sensitivity to onvansertib. PLK1 inhibition is a potential target in KRAS-mutated mCRC, and the combination of onvansertib + FOLFIRI + bevacizumab may provide a new second-line treatment option. Methods: The primary objective of this single-arm Phase 1b/2 study is to assess the safety and preliminary efficacy of onvansertib in combination with FOLFIRI and bevacizumab in the second line setting for KRAS-mutated mCRC patients. For the Phase 1b segment, a standard 3 + 3 dose-escalation design is used to determine the maximum tolerated dose or recommended phase 2 dose (RP2D) of onvansertib. As of September 15th 2020, the first two dose levels have been cleared for safety and the third is enrolling. Efficacy will be determined by objective response rate (ORR) according to RECIST v1.1 (primary endpoint), progression-free survival and reduction in KRAS allelic burden in liquid biopsies (secondary endpoints). Biomarker analyses include genomic profiling of circulating tumor DNA genomic to evaluate altered pathways that correlate with patient clinical response. Based on a one-sided one sample log-rank test with 10% Type I error, there will be at least 90% power to detect an improvement in ORR from 5% to 20% with 32 patients. Clinical trial information: NCT03829410.

TPS153 Background: The clinical benefit of approved therapies in patients (pts) with metastatic colorectal cancer (mCRC) who progress on first- and second-line chemotherapy (FOLFOX and FOLFIRI) is limited. In pts with chemotherapy-refractory RAS wild type mCRC, antibodies targeting EGFR offer a monotherapy response rate of approximately 20% and a progression-free survival (PFS) of 4 months (Price 2014). HER2 is a validated target in gastric and breast cancers, with HER2 amplification occurring in ~3–5% of pts with mCRC. Tucatinib (TUC), recently approved for HER2+ metastatic breast cancer, is a tyrosine kinase inhibitor (TKI) highly selective for HER2 with minimal inhibition of EGFR. In pt-derived xenograft models of HER2+ mCRC, the combination of TUC + trastuzumab (TRAS) showed significantly greater antitumor activity compared with either agent alone (Kulukian 2020). The MOUNTAINEER trial was initiated to evaluate the efficacy and safety of TUC in combination with TRAS in pts with HER2+ RAS wild-type mCRC. Interim analysis of the initial 26 pts enrolled in MOUNTAINEER demonstrated an objective response rate (ORR) of 52.2% (12 partial responses [PRs] in 23 evaluable pts), median duration of response of 10.4 months, with a median PFS of 8.1 months and a median overall survival (OS) of 18.7 months (Strickler 2019). Based on these results, the trial was expanded to enable better estimation of ORR and safety. Methods: MOUNTAINEER (NCT03043313) is an open-label, pivotal phase 2 trial that initially consisted of a single cohort of up to 45 pts (Cohort A) treated with TUC (300 mg BID) and TRAS (8 mg/kg IV followed by 6 mg/kg IV every 3 weeks). The trial was expanded to include an additional 70 pts randomized 4:3 into 2 cohorts: Cohort B (N = 40) who will receive TUC + TRAS, and Cohort C (N = 30) who will receive TUC monotherapy. Pts in Cohort C will be treated with TUC (300 mg orally twice daily) with the option to crossover to TUC + TRAS if an objective response is not achieved by 12 weeks, or if progressive disease develops at any time. Eligible pts have RAS wild-type and HER2+ mCRC, and must have previously received regimens that include fluoropyrimidines, oxaliplatin, irinotecan, anti-VEGF therapy, and an anti-PD-1 if the tumor has dMMR proteins or is MSI-H. Pts who have received prior HER2-directed therapies are not eligible. Additionally, pts must have measurable disease and ECOG PS of 0 to 2. The primary endpoint of this trial is confirmed ORR (per RECIST v1.1) in Cohorts A + B as assessed by blinded independent central review. Secondary endpoints include duration of response, PFS, OS, and safety and tolerability. Enrollment is ongoing in the US and planned for the EU. Clinical trial information: NCT03043313.

TPS149 Background: METamp is a secondary, or co-driving, genetic change in pts with mCRC and acquired resistance to anti-EGFR therapy, which can contribute to disease progression. In EGFR-resistant pts with mCRC and METamp, MET inhibition + an anti-EGFR agent could achieve disease control by targeting emerging MET pathway activation and maintaining EGFR pathway inhibition. Tepotinib is an oral, once-daily, highly selective, potent MET tyrosine kinase inhibitor (TKI). Tepotinib + the EGFR TKI gefitinib demonstrated improved outcomes in pts with EGFR-mutant METamp non-small cell lung cancer and acquired EGFR TKI resistance vs chemotherapy (INSIGHT: NCT01982955). In these pts, progression-free survival (PFS) was 16.6 vs 4.2 months (HR = 0.13; 90% CI: 0.04, 0.43) and overall survival (OS) was 37.3 vs 13.1 months (HR = 0.08; 90% CI: 0.01, 0.51). In pts with mCRC and acquired resistance to anti-EGFR antibody therapy due to METamp, tepotinib + anti-EGFR antibody cetuximab may be active and therefore provide an effective therapeutic option. Methods: This Phase II, multicenter, single-arm, open-label study will assess preliminary antitumor activity, safety and tolerability, and explore pharmacokinetic (PK) profiles of tepotinib + cetuximab in pts with RAS/BRAF wild-type left-sided mCRC and acquired resistance to anti-EGFR antibody-targeted therapy due to METamp. A safety run-in (6-12 pts) will evaluate the recommended Phase II dose of tepotinib to be used in combination with cetuximab (endpoint:dose-limiting toxicities). Enrollment is based on a confirmed advanced left-sided CRC diagnosis, with RAS/BRAF wild-type, documented previous anti-EGFR therapy and acquired resistance on the most recent anti-EGFR antibody and METamp confirmed by liquid and/or tissue biopsy. Pts must be ≥18 years old and have an Eastern Cooperative Oncology Group performance status of 0/1 and normal organ function. The study will screen sufficient pts to account for setting-specific METamp heterogenicity. Approximately 42 pts are planned to receive study treatment: ~22 in Cohort A (tepotinib second-line, outside US) and 20 in Cohort B (tepotinib ≥third-line, US only). Primary endpoint:investigator-assessed objective response (RECIST 1.1). Secondary endpoints are investigator-assessed duration of response (DoR) and PFS (RECIST 1.1), OS, tolerability and safety (NCI-CTCAE v5.0) and cetuximab immunogenicity (measured by antidrug antibody assays at the start and end of treatment). Additional endpoints include assessment of tepotinib and cetuximab PK profiles and expression of biomarkers of resistance (from blood and/or tissue samples). Retrospective assessment of best overall response, DoR and PFS by an independent review committee may be conducted. No formal statistical hypothesis will be tested in this exploratory study. Clinical trial information: NCT04515394.

TPS143 Background: Patients with KRAS and NRAS ( RAS) wild-type mCRC benefit from the epidermal growth factor receptor (EGFR) monoclonal antibodies (Abs) panitumumab and cetuximab, but nearly all patients experience resistance. Blood-based profiling of cell free DNA (cfDNA) can identify genomic alterations that drive acquired EGFR Ab resistance. After discontinuation of anti-EGFR Abs, acquired genomic alterations decay over time to undetectable levels. Some studies have suggested clinical benefit from EGFR Ab rechallenge, but there is limited evidence that EGFR Ab rechallenge improves survival compared to standard of care (SOC) therapies. We hypothesize that cfDNA profiling will identify patients appropriate for panitumumab rechallenge, and that these molecularly selected patients will have improved survival compared to current SOC therapies. Methods: This is a randomized phase II, open label study designed to compare the overall survival (OS) of panitumumab rechallenge versus SOC (investigator choice TAS-102 or regorafenib). Secondary objectives include comparisons of progression free survival, objective response rate, clinical benefit rate, and quality of life as measured by the linear analogue self-assessment (LASA) questionnaire. Eligible patients have radiographically measurable KRAS, NRAS, and BRAF codon 600 wild-type mCRC based on tumor tissue testing, and must have experienced progression or intolerance to treatment with a fluoropyrimidine, oxaliplatin, irinotecan, an anti-VEGF Ab, and an anti-PD-1 Ab if the tumor has mismatch repair deficiency or is MSI-H. Progression after at least 4 months treatment with an anti-EGFR Ab is required. All patients must be enrolled in the COLOMATE cfDNA screening protocol (NCT03765736) and meet molecular eligibility based on Guardant360 cfDNA profiling (absence of amplification of ERBB2, KRAS, NRAS, and MET; absence of mutations of BRAF, EGFR, ERBB2, KRAS, NRAS, and MET [mutant allele frequency > 0.5%]). Greater than 90 days must have elapsed between the most recent treatment with an anti-EGFR Ab and cfDNA profiling. Dosing for all study drugs is according to clinical SOC. 120 patients will be randomized 1:1 to panitumumab rechallenge or SOC. With 83 OS events, this study will have 80% power to detect an improvement in median OS from 6.5 to 10 months (HR=0.65; 1-sided α= 0.15). This study began enrollment in 6/2020. Recruitment is ongoing at 16 sites in the Academic and Community Cancer Research United (ACCRU) network (ACCRU-GI-1623). Clinical trial information: NCT03992456.

423 Background: Advanced PDAC remains a deadly disease with a 5-year survival rate of less than 10%. cfDNA - based next generation sequencing (NGS) may identify actionable alterations in patients with PDAC. In this study, we aim to determine the feasibility of utilizing serial cfDNA NGS testing and its potential relevance in predicting therapeutics outcomes. Methods: A total of 23 PDAC patients with PDAC cfDNA isolated from plasma collected at diagnosis and upon disease progression to first line SOC therapy and were analyzed on a 73-74 gene NGS panel (Guardant Health). Changes in molecular profiles from baseline to progression were analyzed for overall survival, progression free survival (PFS), and treatment response. PFS and OS were analyzed using the Kaplan-Meier method and the log-rank test was used to compare the survival of different groups of patients. All p-values were two-sided. Analyses were performed using R (version 3.5.1, R Foundation, Vienna, Austria). Results: In this retrospective study, the 1-year probability of survival was 71% (median 473 days) and the 1-year PFS was 14% (median 212 days). TP53 and KRAS were the most frequently mutated genes identified in baseline samples, with 78% prevalence for each. Patients with clearance of TP53 17% (3/18) patients and/or KRAS 33% (6/18) patients clones after first line therapy significantly increases PFS (p=0.0056 and p=0.037, with HR of 0.087 and 0.32, respectively). However, appearance of TP53 or KRAS alterations upon progression does not significantly affect overall survival or PFS. Conclusions: The preliminary results from this study suggest that cfDNA clearance of TP53 and/or KRAS alterations may predict for improved PFS in PDAC. Confirmation of these findings in larger studies is warranted.

413 Background: Vascular endothelial growth factor (VEGF) and VEGF receptor (VEGFR)-mediated signaling and angiogenesis contribute to the pathogenesis and progression of pancreatic adenocarcinoma (PCA).VEGF is expressed in all PCA tumors. VEGF-A/VEGFR-2 signaling plays an important role in inducing invasion and migration of PCA cells. The pVEGFR-2 is significantly associated with invasion of the anterior capsule of pancreas and arteries. In preclinical studies, the anti-tumor activity of fluoropyrimidines, but not that of gemcitabine, caused the release of bone marrow derived circulating endothelial progenitor cells (CEPs) and Tie-2 expressing monocytes (TEMs) as well as the induction of pro-angiogenic growth factors. Methods: This phase II randomized, multi-center, and double-blinded trial was designed to compare the efficacy and safety of mFOLFIRINOX/ramucirumab (Arm A) versus mFOLFIRINOX/ placebo (Arm B) as front-line therapy in recurrent or metastatic PCA patients. The primary endpoint was progression free survival (PFS) at 9 months, and the secondary endpoints included overall survival (OS) and response rate. Results: A total of 86 subjects were enrolled, 82 were eligible (42 in Arm A v. 40 in Arm B). The mean age of the subjects in the two arms were comparable (61.7 v. 63.0, respectively); 43 male, 69 Caucasian. On the univariate analysis, there was no difference in distribution between the 2 arms for age, gender, race and ethnicity. The median PFS was 5.6 in Arm A compared to 6.7 months in Arm B (one-sided log-rank, p = 0.322). At 9 months, the progression free rates were 25.1% v. 35% for Arms A and B, respectively. The mFOLFIRINOX/ramucirumab combination was well tolerated. Patients in Arm A reported a slightly higher number of adverse events (AEs) encounters, most commonly diarrhea (29 vs 28), fatigue (25 v. 25), vomiting (24 v. 14), weight loss (23 v. 17), and abdominal pain (20 v. 15). Arm A had more SAEs than Arm B (43 v. 25), with sepsis most commonly reported in both arms (3 in each), vomiting (3 v. 2), diarrhea (3 v.1) and duodenal obstruction (3 v. 0). Arm B had a slightly higher response rate (22.58%) compared to Arm A (17.65%) that was not statistically significant. The median OS in Arm A was 10.3 compared to 9.7 months for Arm B (one-sided log-rank, p = 0.094). Conclusions: In this randomized phase 2 study, the addition of ramucirumab to mFOLFIRINOX did not improve PFS, response rate, or OS as initial therapy for metastatic pancreatic cancer. FOLFIRINOX/Ramucirumab combination was well tolerated in the treatment of PCA. Clinical trial information: NCT02581215.

402 Background: Pancreas cancer is an aggressive malignancy with limited therapeutic options. Nanoliposomal irinotecan (Nal-IRI) is a preferred second-line treatment, and current guidelines recommend its use in the absence of prior irinotecan. This study aimed to assess whether patients who had received regular irinotecan derive benefit from Nal-IRI. Methods: Medical records of metastatic pancreas cancer patients who had received regular irinotecan and then Nal-IRI were reviewed. The following information was extracted from each medical record: patient demographics, confirmation of a diagnosis of exocrine pancreas cancer, initial cancer stage, dates of administration of the drugs of interest, adverse events that occurred with Nal-IRI treatment, reasons for stopping regular irinotecan, and reasons for starting and stopping Nal-IRI. The primary endpoint was overall survival after the initiation of Nal-IRI (an a priori threshold of > 4 months defined success). Survival data were censored based on date of last follow up. Direct quotes from the medical record were documented to provide insight on prescribing Nal-IRI when guidelines advised the contrary. Results: Sixty four patients met eligibility criteria with a median age of 65 years (range: 36, 80 years). Prior to Nal-IRI, 61 patients had received FOLFIRINOX, and 3 FOLFIRI. Of these, 32 patients manifested progressive disease on regular irinotecan-based therapy. Nal-IRI was prescribed with a fluoropyrimidine; only one patient received monotherapy. At time of analysis, 54 patients had died. Median overall survival from initiation of Nal-IRI was 5.1 months (95% confidence interval (CI): 5.6, 4.3, months). An exploratory comparison, based on no cancer progression with regular irinotecan versus progression, showed improved survival with Nal-IRI in the former group: 6.1 months (95% CI: 9.3, 5.1 months) versus 4.3 months (95% CI: 4.8, 2.3 months); p=0.0006. Nal-IRI adverse events occurred as expected. Qualitative data illustrated several themes, including “limited treatment options,” which appeared to drive the decision to prescribe Nal-IRI. Conclusions: Nal-IRI might be considered in pancreas cancer patients who had received regular irinotecan, particularly in the absence of disease progression with the latter.