Diverse and precision therapies open new horizons for patients with advanced pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a common cause of cancer-related death, and most patients are with advanced disease when diagnosed. At present, despite a variety of treatments have been developed for PDAC, few effective treatment options are available; on the other hand, PDAC shows significant resistance to chemoradiotherapy, targeted therapy, and immunotherapy due to its heterogeneous genetic profile, molecular signaling pathways, and complex tumor immune microenvironment. Nevertheless, over the past decades, there have been many new advances in the key theory and understanding of the intrinsic mechanisms and complexity of molecular biology and molecular immunology in pancreatic cancer, based on which more and more diverse new means and reasonable combination strategies for PDAC treatment have been developed and preliminary breakthroughs have been made. With the continuous exploration, from surgical local treatment to comprehensive medical management, the research-diagnosis-management system of pancreatic cancer is improving. This review focused on the variety of treatments for advanced PDAC, including traditional chemotherapy, targeted therapy, immunotherapy, microenvironment matrix regulation as well as the treatment targeting epigenetics, metabolism and cancer stem cells. We pointed out the current research bottlenecks and future exploration directions.

Update on optimal management for pancreatic cancer: expert perspectives from members of the Australasian Gastrointestinal Trials Group (AGITG) with invited international faculty

INTRODUCTION

Pancreatic cancer remains a challenging malignancy due to the high proportion of patients diagnosed at advanced stages and the limited treatment options. This article discusses recent evidence in the management of both localized and advanced pancreatic cancer and offers an expert opinion on current best practice.

AREAS COVERED

For patients with localized disease, the evidence for adjuvant chemotherapy is discussed as well as emerging neoadjuvant approaches for resectable, borderline resectable, and locally advanced disease. Advances in metastatic disease are discussed including cytotoxic chemotherapy, targeted therapies, and the role of genomic testing to identify patients with molecular alterations. Reviewed literature included journal publications, abstracts presented at major international oncology meetings, and ongoing clinical trials databases.

EXPERT OPINION

Pancreatic cancer is a devastating diagnosis and despite recent advances has a very poor prognosis. Only a minority of patients, 20%, are diagnosed with potentially curable disease. The shifting paradigm toward neoadjuvant therapy may improve resectability and survival rates; however, robust evidence is required. Thus far, there has only been limited progress in advanced stage disease. Genomic testing may potentially identify more treatment targets although limited to small subgroups.

The biological underpinnings of therapeutic resistance in pancreatic cancer

In this review, Beatty et al. discuss recent advances in our understanding of the biological underpinnings of pancreatic ductal adenocarcinoma (PDAC) and dissect therapeutic targets that are intrinsic to PDAC and those that are defined by noncancer cells, including stromal cells, immune cells, and microbes.

Pancreatic ductal adenocarcinoma (PDAC) is a leading cause of cancer-related mortality in the United States and has only recently achieved a 5-yr survival rate of 10%. This dismal prognosis reflects the remarkable capacity of PDAC to effectively adapt to and resist therapeutic intervention. In this review, we discuss recent advances in our understanding of the biological underpinnings of PDAC and their implications as targetable vulnerabilities in this highly lethal disease.

Molecular characteristics of BRCA1/2 and PALB2 mutations in pancreatic ductal adenocarcinoma

INTRODUCTION

Poly-(ADP)-ribose polymerase (PARP) inhibitors are successfully used for treatment of BRCA-mutated (mut) breast cancers and are under extensive evaluation for BRCA- and PALB2-mutated pancreatic ductal adenocarcinoma (PDAC). However, the optimal treatment regimen for BRCA/PALB2-mutated PDCA has yet to be established. Moreover, limited data are available on the association of BRCA/PALB2 gene alterations with other comutations and immunological biomarkers.

MATERIAL AND METHODS

Tumour samples of 2818 patients with PDAC were analysed for BRCA1/2 PALB2 mutations and other genes by next-generation sequencing (NGS) (MiSeq on 47 genes, NextSeq on 592 genes). TMB was calculated based on somatic non-synonymous missense mutations. MSI-H/dMMR was evaluated by NGS, and PD-L1 expression was determined using immunohistochemistry.

RESULTS

In 4.2% (n=124) of all PDAC samples BRCA mutations have been detected. BRCA2 mutations were more commonly observed than BRCA1 mutations (3.1%(n=89) vs 1.1% [n=35], p<0.0001). BRCA2 mutation was associated with an older age (64 vs 61 years for wild-type (wt), p=0.002) and PALB2 mutation was observed more frequently in female than in male patients. BRCA and PALB2 mutations were associated with MSI-H/dMMR compared with wt (BRCA: 4.8% vs 1.2%, p=0.002; PALB2: 6.7% vs 1.3 %, p=0.18), PD-L1 expression of >1.0% (BRCA: 21.8% vs wt 11.2%, p<0.001, PALB2: 0.0% vs 12.4 %, p=0.38) and high TMB (BRCA: mean 8.7 vs 6.5 mut/MB, p<0.001; PALB2: 10.6 mut/Mb vs 6.6 mut/Mb, p=0.0007). Also, PD-L1 expression and TMB differed between BRCA and PALB2 mutation and wt samples in MSS tumours (p<0.05). BRCA-mutated and PALB2-mutated PDACs were characterised by a different mutational profile than was observed in wt tumours.

CONCLUSIONS

BRCA and PALB2 mutations were found in a significant subgroup of PDACs. These mutations were associated with a distinct molecular profile potentially predictive for response to immune-checkpoint inhibitor therapy. Therefore, these data provide a rationale to evaluate PARP inhibitors in combination with immune-checkpoint inhibitors in patients with BRCA/PALB2-mutated PDAC.

PARP inhibition in treatment of pancreatic cancer

INTRODUCTION

Tumor control and survival of patients with metastatic pancreatic ductal adenocarcinoma (PDAC) has improved with more effective polychemotherapies. The identification of novel therapeutic targets is strongly needed in order to propose maintenance therapies that improve quality of life while maintaining tumor control.

AREAS COVERED

PDAC with mutations in homologous recombination repair genes such as BRCA are particularly sensitive to platinum agents. Recently, the potential role of poly(ADP-ribose) polymerase (PARP) inhibitors was suggested. The POLO study has shown that olaparib was efficient and well-tolerated as maintenance therapy in patients with germline BRCA1/2 mutation and a metastatic PDAC controlled after a platinum-based induction chemotherapy.

EXPERT OPINION

The demonstration of olaparib efficacy in patients with metastatic PDAC and BRCA germline mutation has paved the way for maintenance with a targeted therapy. Further studies are needed to assess; the potential role for PARPI in earlier forms of PDAC, those with somatic or more rare BRACness signatures, to overcome primary or secondary resistances to PARPi, and to combine them with other antitumoral agents.