Pancreatic Cancer: A Review of Current Treatment and Novel Therapies

Pancreatic cancer is one of the leading causes for cancer-related deaths in the United States. Majority of patients present with unresectable or metastatic disease. For those that present with localized disease, a multidisciplinary approach is necessary to maximize survival and optimize outcomes. The quality and safety of surgery for pancreatic cancer have improved in recent years with increasing adoption of minimally invasive techniques and surgical adjuncts. Systemic chemotherapy has also evolved to impact survival. It is now increasingly being utilized in the neoadjuvant setting, often with concomitant radiation. Increased utilization of genomic testing in metastatic pancreatic cancer has led to better understanding of their biology, thereby allowing clinicians to consider potential targeted therapies. Similarly, targeted agents such as PARP inhibitors and immune checkpoint- inhibitors have emerged with promising results. In summary, pancreatic cancer remains a disease with poor long-term survival. However, recent developments have led to improved outcomes and have changed practice in the past decade. This review summarizes current practices in pancreatic cancer treatment and the milestones that brought us to where we are today, along with emerging therapies.

Abstract 3869: Short or long-term treatment with CDK4/6 inhibitors in patients with ER+ breast cancer: characterization and comparative analysis of resistance in seventeen XPDX models

Background: Mechanisms of resistance to CDK4/6 inhibitors (CDK4/6i) have been well studied and several alterations identified including RB loss and altered expression of related genes including CCNE1, E2F4 and CDK6. However, whether duration of clinical treatment might elicit specific mechanism(s) of CDK4/6i resistance is unclear. To better understand if duration of clinical treatment correlates with unique resistance mechanisms, we established, characterized, and compared a panel of ER+ breast XPDX models from patients who benefitted then progressed on a CDK4/6i. Patients were separated into two groups by time to progression (TTP): those who responded up to twelve months (RES12) and patients with clinical response greater than one year (RES13+).

Methods: Seventeen breast cancer XPDX models were analyzed, including eight previously described (7xRES12; 1xRES13+: SABCS2021: T Hernandez et al). Nine new models were established from seven patients: six from fluid samples with three designated as ductal (ST3105B, ST3105C, STM001B) and three lobular carcinoma (STM182, STM229, STM229B); two from lymph node biopsies (ST5676, STM127) and one from a liver core biopsy (ST4887B), all reported as ductal carcinoma. STM182 was classified as RES12 and the remaining eight as RES13+. These models were passaged and challenged with CDK4/6i to confirm resistance. Receptor expression was determined by IHC and genomic analyses including WES and RNAseq, were performed to identify mechanisms of resistance. For in vivo studies, CDK4/6i were dosed PO once daily at 50 mg/kg; endpoints included tumor volume (TV) and time from treatment initiation (TTI) with %T/C values and tumor regression reported at study completion; a %T/C of ≤20 versus control was considered sensitive. Tumor regression (%T/C<0) versus Day 0 TV was also reported.

Results: Clinical TTP for RES12 (n=8) was four to twelve months and RES13+ (n=9) from thirteen to forty-two months. All models retained ER expression in evaluated passages with similar histology compared with archival clinical samples. Sequencing identified several variants including RB1 truncations or deletions and increased gene expression in CCND1, CCNE1 and the PIK3CA/AKT pathway. Interestingly, 5/8 RES12 models reported ESR1 mutations or fusions versus 1/9 RES13+ and PIK3CA mutations were reported in 1/8 RES12 versus 5/9 RES13+. Several RES13+ models also reported variants and increased amplification in the RICTOR/TORC2 pathway versus RES12.

Conclusion: We have established, characterized, and compared a panel of seventeen breast XPDX models from fourteen female patients representing early or late acquired resistance to CDK4/6i therapy and identified potential differences in each set. These models and resulting data are useful in developing novel therapies for CDK4/6i-resistant patients.

Citation Format: Alyssa Simonson, Johnnie Flores, Morgan Lynch, Emily Carpenter, Justine Hruzek, Jim Lund, Natalia Baños Herraiz, Kyriakos Papadopoulos, Amy Vander Woude, Gladys Rodriguez, Sreenivasa Chandana, Thomas Gribbin, Nehal Lakhani, Tatiana Hernandez, Maria Jose de Miguel, Amy Lang, Michael J. Wick. Short or long-term treatment with CDK4/6 inhibitors in patients with ER+ breast cancer: characterization and comparative analysis of resistance in seventeen XPDX models. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3869.

Abstract OT2-01-01: Phase 1 study of ST101, a first-in-class peptide antagonist of CCAAT/enhancer-binding protein β (C/EBPβ), in patients with advanced solid tumors, with a phase 2 expansion in patients with hormone receptor positive breast cancer (HR+ BC)

Background: CCAAT/Enhancer Binding Protein Beta (C/EBPβ) is a transcription factor that is active during embryofetal development but held in an inactive state in most mature cells. C/EBPβ is upregulated or overactivated in multiple cancers, where it inversely correlates with disease prognosis. In breast cancer, C/EBPβ drives the expression of factors that promote tumor survival, proliferation and inhibit differentiation. ST101 is a cell-penetrating all D amino acid peptide antagonist of C/EBPβ. ST101 exposure inhibits C/EBPβ target gene expression, leading to selective tumor cell death in multiple human cancer cell lines, including hormone receptor positive breast cancer (HR+ BC) and triple negative breast cancer (TNBC), without impacting normal cell viability. In vivo, ST101 displays rapid uptake into multiple organs, the ability to cross the blood-brain barrier, and a long plasma half-life due to its resistance to proteolytic degradation. Potent ST101 anti-tumor activity, demonstrated by dose-dependent inhibition of tumor growth in subcutaneous HR+ and orthotopic TNBC xenograft models in vivo, supported advancing ST101 into clinical development.Trial design: This phase 1-2 study uses a standard 3+3 design with dose doubling for the first 4 dose levels then 50% escalations thereafter. The recommended phase 2 dose will be used in 4 expansion cohorts in specific tumor types, including HR+ BC. Patients receive intravenous ST101 once weekly.Eligibility criteria: The dose-escalation phase is enrolling patients ≥18 years of age with advanced, unresectable metastatic solid tumors refractory to or intolerant of other therapeutic options. In expansion, patients with HR+ BC must have progressed after 1-3 prior hormone-based therapies. Previous treatment with CDK 4/6 inhibitor, mTOR inhibitor, or chemotherapy is allowed as monotherapy or in combination. Specific aims: The primary objective of phase 1 is to evaluate safety and tolerability of ST101. Secondary objectives include the recommendation of a dose and regimen of ST101 for further evaluation, analysis of pharmacokinetics, assessment of several pharmacodynamic measures, and to assess preliminary efficacy. Statistical design: The recommended phase 2 dose will be used in a 15-30 patient HR+ BC expansion cohort, with a Simon 2-stage design, which requires one response to expand the cohort to 30 patients. Up to 120 patients are planned in a total of four expansion cohorts, which should be enrolling by Q3 2021.Accrual: We began recruitment in August 2020. Enrollment is ongoing, and by July 2021, 18 patients were recruited in five dose-escalation cohorts up to 6 mg/kg; a 6th cohort (9 mg/kg) is ongoing. Dose escalation should be complete by Sept 2021, and the phase 2 portion in the HR+ BC cohort will be underway (n=15-30). Please contact rob.michel@bexonclinical.com if you have a specific interest in this trial.

Citation Format: Alice S Bexon, Hendrik-Tobias Arkenau, Jeff Evans, Gerald S Falchook, Stefan N Symeonides, Meredith A McKean, Elisa Fontana, Manojkumar Bupath, Alistair McLaren, Sreenivasa Chandana, Tze-en Ding, Emerson A Lim, Jim Rotolo, Gina Capiaux, Rob Michel, Stephen Kaesshaefer, Nehal J Lakhani. Phase 1 study of ST101, a first-in-class peptide antagonist of CCAAT/enhancer-binding protein β (C/EBPβ), in patients with advanced solid tumors, with a phase 2 expansion in patients with hormone receptor positive breast cancer (HR+ BC) [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr OT2-01-01.

Abstract P06-03: ST101, a peptide targeting oncogenic transcription factor C/EBPβ: initial safety, efficacy, pharmacokinetic (PK) and pharmacodynamic (PD) data from an ongoing phase 1 dose escalation study in patients with advanced, metastatic solid tumors

Introduction: The oncogenic transcription factor CCAAT/enhancer-binding protein β (C/EBPβ) is normally active in embryofetal development, but inactive and suppressed in mature cells. Upregulation or activation of C/EBPβ in cancer promotes tumor survival and proliferation while inhibiting its differentiation. ST101 is a peptide antagonist of C/EBPβ, with anti-tumor activity in glioblastoma (GBM), breast cancer (BC), prostate cancer (PC), melanoma, and other models. ST101 penetrates the blood-brain barrier, as demonstrated in a mouse model and biodistribution studies. We have also demonstrated the tumor-specificity of ST101 in numerous in vitro cell lines. Methods: We conducted the phase 1 portion of a phase 1-2 study in patients with refractory solid tumors. The primary objective was to evaluate safety and tolerability of ST101. Secondary and exploratory objectives included PK, preliminary efficacy, and PD from serial biopsies. The study used a 3+3 design, dosing ST101 IV at 0.5, 1, 2, 4, 6, and 8 (now modified to 9) mg/kg weekly (QW). Phase 2 will include four cohorts of patients with specific cancers: HR+ breast cancer, cutaneous melanoma, GBM, and castrate-resistant PC at the recommended phase 2 dose (RP2D). Results: As of July 2021, 18 pts were enrolled, and the last cohort (9 mg/kg) is underway. Patients received a median of 6 weeks’ treatment (range 2 – 45). There were no dose-limiting toxicities, dose modifications, or SAEs related to ST101. The only adverse events (AEs) of note were G1-2 histaminergic infusion-related reactions (IRRs), largely pruritis and urticaria, managed with antihistamines, montelukast, and interruption/slowing of infusion. IRRs affected 100% pts on the 1st dose of ST101 at 4mg/kg. Montelukast was added to the antihistamine premedication regimen in the 6 mg/kg cohort, which attenuated IRRs. 66% of patients in the 6 mg/kg experienced an IRR on the first dose. The intensity and frequency of IRRs decreased with repeat dosing across all cohorts. No other AEs were consistently reported. PK was dose-proportionate, with continued exposure. There was no evidence of accumulation, and no anti-drug antibodies were detected. Tumor immunohistochemistry showed dose-proportionate staining for ST101 and a trend of decreased Ki67 staining (proliferation marker) after ST101 exposure. One confirmed partial response in a patient with metastatic cutaneous melanoma refractory to standard therapy is still on study, and 3 pts with varied histologies have had stable disease lasting 18-45 weeks (1 ongoing). Conclusions: ST101 demonstrated safety at all doses explored and evidence of efficacy across dose levels, particularly higher doses. PK and PD support a dose relationship for efficacy, and we will select a QW RP2D for the phase 2 expansion cohorts by September 2021.

Citation Format: Nehal J. Lakhani, Hendrik-Tobias Arkenau, Stefan N. Symeonides, Jeffry Evans, Meredith A. McKean, Elisa Fontana, Manojkumar Bupath, Alistair McLaren, Sreenivasa Chandana, Tze-en Ding, Emerson A. Lim, Jim Rotolo, Gina Capiaux, Rob Michel, Stephen Kaesshaefer, Alice S. Bexon, Gerald S. Falchook. ST101, a peptide targeting oncogenic transcription factor C/EBPβ: initial safety, efficacy, pharmacokinetic (PK) and pharmacodynamic (PD) data from an ongoing phase 1 dose escalation study in patients with advanced, metastatic solid tumors [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P06-03.

Recurrence and survival after curative-intent treatment for colorectal liver metastases: Implications for adjuvant liver-directed regional chemotherapy

BACKGROUND

This study investigates tumor recurrence patterns and their effect on postrecurrence survival following curative-intent treatment of colorectal liver metastases (CRLM) to identify those who stand to benefit the most from adjuvant liver-directed therapy.

METHODS

This is a retrospective analysis of all patients that underwent liver resection and/or ablation for CRLM between 2007 and 2019. Postrecurrence survival was compared between recurrence locations. Risk factors for liver recurrence were sought.

RESULTS

The study included 227 patients. Majority were treated with resection (71.0%) while combination resection/ablation (18.9%) and ablation alone (11.0%), were less common. At a median follow-up of 3.0 years, recurrence was observed in 151 (66.5%) patients. Of those, liver, lung, and peritoneal recurrence were most common at 66.9%, 49.6%, and 9.2%, respectively. Median postrecurrence survival after liver, lung, and multisite recurrence was 39.6-, 68.4-, and 33.6 months, respectively. High tumor grade (p < 0.014), perineural invasion (p = 0.002), and N0 node status (p = 0.017) of primary tumor correlated with liver recurrence on multivariate analysis.

CONCLUSIONS

Tumor grade, perineural invasion, and N0 node status of the primary tumor are associated with increased risk of liver recurrence after CRLM resection and represent a target population that may benefit the most from adjuvant liver-directed regional chemotherapy.

Abstract CT056: A Phase Ia/IIa trial of AVID100, an anti-EGFR antibody-drug conjugate

Background

AVID100, a rationally designed anti-EGFR-DM1 conjugate, showed potent activity in preclinical models, including cancer cell lines resistant to approved anti-EGFR monoclonal antibodies. In addition, AVID100 showed increased toxicity on tumor cells compared to the unconjugated antibody. There was no increased AVID100-mediated toxicity on keratinocytes.

Methods

In the completed Phase Ia segment, 24 patients with advanced or metastatic epithelial malignancies without available standard of care therapy and likely to express EGFR were enrolled into sequential dose-escalation cohorts to assess safety, tolerability, pharmacokinetic (PK) parameters, and to identify the recommended Phase II dose (R2PD) of 2 hour infusions on an every 3 week schedule. In the ongoing Phase IIa segment, preliminary antitumor activity is being assessed in expansion cohorts of patients with high EGFR expression, including triple-negative breast cancer (TNBC) (2+ expression in ≥75% or 3+ in ≥50% of tumor cells) or either squamous cell carcinoma of the head and neck (SCCHN) or squamous non-small cell lung carcinoma (sqNSCLC) (3+ expression in ≥ 50% of tumor cells). The DAKO PharmDx assay was validated and used for screening intensity of EGFR protein expression.

Results

During Phase Ia, no Cycle 1 dose limiting toxicities (DLTs) were observed in Cohorts 1-6 at doses (N) of 20 (1), 40 (1), 80 (3), 120 (3), 180 (3), and 220 (6) mg/m2. In Cohort 7 (6) (270 mg/m2; ~ 7.3 mg/kg) two patients experienced Cycle 1 DLTs (G3 asymptomatic lipase elevation, G4 reversible thrombocytopenia), exceeding the maximally tolerated dose. A third patient developed G3 reversible pneumonitis. As a result, 220 mg/m2 (~6 mg/kg) was selected as the R2PD. Tumor types in greater than one patient included: colorectal (13), breast (4), and ovarian (2). Preliminary PK results at the R2PD revealed exposure exceeding preclinically predicted therapeutic levels. Cmax increased proportionally with dose, plasma half-life was ~50 hours at the R2PD, and clearance decreased with increasing doses with saturation observed between 180-270 mg/m2. Safety and tolerability were acceptable. Other treatment-related adverse events included: infusion-related reactions that were ameliorated by premedication and infusion prolongation, rash, nausea, vomiting, fatigue, headache, anorexia, mucositis, punctate keratitis, diarrhea, elevated amylase, reversible transaminase and alkaline phosphatase elevations without other evidence of hepatotoxicity, hypomagnesemia, and hypokalemia. Prolonged disease stabilization was observed in 3 of these patients not selected for EGFR overexpression (colorectal, ovarian, cervical).

Conclusions

AVID100 is a well-tolerated anti-EGFR-DM1 conjugate with evidence for exposure levels at or above those observed for cetuximab and ado-trastuzumab emtansine. Antitumor activity is currently being evaluated in EGFR-overexpressing patients in Phase IIa.

Citation Format: Nehal Lakhani, Sreenivasa Chandana, Anthony Tolcher, Yvette Cole, Karla Rivas, Sandra Sinclair, Paul I. Nadler, Debra L. Wood, Kyri P. Papadopoulos. A Phase Ia/IIa trial of AVID100, an anti-EGFR antibody-drug conjugate [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT056.

Role of mixed lineage kinase 3 in response of head and neck squamous cancer cell lines to epidermal growth factor receptor (EGFR) inhibition

6076

Background: More efficacious treatments of head and neck squamous cancers (HNSCC) are urgently needed. HNSCC overexpress EGFR, yet the efficacy of EGFR inhibitors is marginal, with minimal effect on patient survival. Mixed lineage kinases (MLKs) are members of a large family of mitogen-activated protein kinase (MAPK) kinase kinases (MAPKKKs) that activate MAPK pathways, involving JNK, ERK 1/2 and p38 cell signaling pathways. (Gallo KA, Johnson GL, Nat Rev Mol Cell Biol. 2002;3:663–72) We explored the role of MLK3 in HNSCC as a possible therapeutic target. Methods: The requirement of MLK3 for cell proliferation and survival of HNSCC cell lines UM-SCC-38 and -47 (HPV+) (obtained from TE Carey, U Michigan) was investigated using RNA interference (siRNA) and MLK3 inhibitor K252a to inhibit the expression and activity of MLK3. Cells were also exposed to EGFR inhibitor Compound 56 at various concentrations. Proliferation was assessed with MTT after 72 h exposure. The effect of MLK3 inhibition on relevant cell signaling pathways was assessed by immunoblotting with activation-specific phosphoantibodies directed against MAPKs, the prosurvival kinase Akt and apoptotic proteins. Results: MLK3 is overexpressed in malignant HNSCC cell lines compared to normal tonsil lysate, and its expression can be inhibited by siRNA or K 252a. Inhibition of MLK3 expression is associated with downregulation of phospho-Akt and with decreased proliferation. Compound 56 inhibits proliferation at lower concentrations in HPV+ cell line UM-SCC-47 (10 microM) compared with UM-SCC-38 (25 microM), inhibits expression of pErk, and decreases expression of pAkt. Combining siRNA or K252a and compound 56 showed less pAkt expression and increased apoptosis (caspase 3 or PARP cleavage) compared with compound 56 alone. Conclusions: MLK3 may have a role in avoiding apoptosis in HNSCC cells. Its inhibition may enhance the effects of EGFR inhibition in HNSCC.

No significant financial relationships to disclose.

LeuO-mediated transcriptional derepression

To understand the coordination of gene expression in the Salmonella typhimurium ilvIH-leuO-leuABCD gene cluster, we had previously identified a 72-bp AT-rich (78% A+T) DNA sequence element, AT4, which was capable of silencing transcription in a promoter nonspecific manner. LeuO protein provided in trans relieved (derepressed) AT4-mediated gene silencing (transcriptional repression), but underlying mechanisms remained unclear. In the present communication, the 72-bp DNA sequence element is further dissected into two functional elements, AT7 and AT8. LeuO binds to the 25-bp AT7, which lies closest to the leuO promoter in the AT4 DNA. After deletion of the AT7 DNA sequence responsible for LeuO binding from AT4, the remaining 47-bp AT-rich (85% A+T) DNA sequence, termed AT8, retains the full bi-directional gene-silencing activity, which is no longer relieved by LeuO. LeuO-mediated transcriptional derepression is restored when the LeuO binding site, AT7, is placed within close proximity to the gene silencer AT8. As a pair of functionally coupled transcription elements, the presence of an equal copy number of AT7 and AT8 within proximity is important for the transcription control. The characterization provides clues for future elucidation of the molecular details whereby LeuO negates the gene-silencing activity.

Heterogeneity in 2-deoxy-D-glucose-induced modifications in energetics and radiation responses of human tumor cell lines

PURPOSE

The glucose analog and glycolytic inhibitor, 2-deoxy-D-glucose (2-DG), has been shown to differentially enhance the radiation damage in tumor cells by inhibiting the postirradiation repair processes. The present study was undertaken to examine the relationship between 2-DG-induced modification of energy metabolism and cellular radioresponses and to identify the most relevant parameter(s) for predicting the tumor response to the combined treatment of radiation + 2-DG.

METHODS AND MATERIALS

Six human tumor cell lines (glioma: BMG-1 and U-87, squamous cell carcinoma: 4451 and 4197, and melanoma: MeWo and Be-11) were investigated. Cells were exposed to 2 Gy of Co-60 gamma-rays or 250 kVP X-rays and maintained under liquid-holding conditions 2-4 h to facilitate repair. 2-DG (5 mM, equimolar with glucose) that was added at the time of irradiation was present during the liquid holding. Glucose utilization, lactate production (enzymatic assays), and adenine nucleotides (high performance liquid chromatography and capillary isotachophoresis) were investigated as parameters of energy metabolism. Induction and repair of DNA damage (comet assay), cytogenetic damage (micronuclei formation), and cell death (macrocolony assay) were analyzed as parameters of radiation response.

RESULTS

The glucose consumption and lactate production of glioma cell lines (BMG-1 and U-87) were nearly 2-fold higher than the squamous carcinoma cell lines (4197 and 4451). The ATP content varied from 3.0 to 6.5 femto moles/cell among these lines, whereas the energy charge (0.86-0.90) did not show much variation. Presence of 2-DG inhibited the rate of glucose usage and glycolysis by 30-40% in glioma cell lines and by 15-20% in squamous carcinoma lines, while ATP levels reduced by nearly 40% in all the four cell lines. ATP:ADP ratios decreased to a greater extent ( approximately 40%) in glioma cells than in squamous carcinoma 4451 and MeWo cells; in contrast, presence of 2-DG reduced ADP:AMP ratios by 3-fold in the squamous carcinoma 4451, whereas an increase was noted in the glioma cell line BMG-1. 2-DG significantly reduced the initial rates of DNA repair in all cells, resulting in an excess residual damage after 2 h of repair in BMG-1, U-87, and 4451 cell lines, whereas no significant differences could be observed in the other cell lines. Recovery from potentially lethal damage was also significantly inhibited in BMG-1 cells. 2-DG increased the radiation-induced micronuclei formation in the melanoma line (MeWo) by nearly 60%, while a moderate (25-40%) increase was observed in the glioma cell lines (BMG-1 and U-87). Presence of 2-DG during liquid holding (4 h) enhanced the radiation-induced cell death by nearly 40% in both the glioma cell lines, while significant effects were not observed in others.

CONCLUSIONS

The modifications in energetics and radiation responses by 2-DG vary considerably among different human tumor cell lines, and the relationships between energy metabolism and various radiobiologic parameters are complex in nature. The 2-DG-induced modification of radiation response does not strictly correlate with changes in the levels of ATP. However, a significant enhancement of the radiation damage by 2-DG was observed in cells with high rates of glucose usage and glycolysis, which appear to be the two most important factors determining the tumor response to the combined treatment of 2-DG + radiation therapy.