Pathological treatment response has different prognostic implications for pancreatic cancer patients treated with neoadjuvant chemotherapy or chemoradiotherapy

Identification of tumour regression in neoadjuvantly treated pancreatic cancer is based on divergent and nonspecific criteria

AIMS

Following the increased use of neoadjuvant therapy for pancreatic cancer, grading of tumour regression (TR) has become part of routine diagnostics. However, it suffers from marked interobserver variation, which is mainly ascribed to the subjectivity of the defining criteria of the categories in TR grading systems. We hypothesized that a further cause for the interobserver variation is the use of divergent and nonspecific morphological criteria to identify tumour regression.

METHODS AND RESULTS

Twenty treatment-naïve pancreatic cancers and 20 pancreatic cancers treated with neoadjuvant chemotherapy were reviewed by three experienced pancreatic pathologists who, blinded for treatment status, categorized each tumour as treatment-naïve or neoadjuvantly treated, and annotated all tissue areas they considered showing tumour regression. Only 50%-65% of the cases were categorized correctly, and the annotated tissue areas were highly discrepant (only 3%-41% overlap). When the prevalence of various morphological features deemed to indicate TR was compared between treatment-naïve and neoadjuvantly treated tumours, only one pattern, characterized by reduced cancer cell density and prominent stroma affecting a large area of the tumour bed, occurred significantly more frequently, but not exclusively, in the neoadjuvantly treated group. Finally, stromal features, both morphological and biological, were investigated as possible markers for tumour regression, but failed to distinguish TR from native tumour stroma.

CONCLUSION

There is considerable divergence in opinion between pathologists when it comes to the identification of tumour regression. Reliable identification of TR is only possible if it is extensive, while lesser degrees of treatment effect cannot be recognized with certainty.

Pathological Complete Response in Patients With Resected Pancreatic Adenocarcinoma After Preoperative Chemotherapy

Importance

Preoperative chemo(radio)therapy is increasingly used in patients with localized pancreatic adenocarcinoma, leading to pathological complete response (pCR) in a small subset of patients. However, multicenter studies with in-depth data about pCR are lacking.

Objective

To investigate the incidence, outcome, and risk factors of pCR after preoperative chemo(radio)therapy.

Design, Setting, and Participants

This observational, international, multicenter cohort study assessed all consecutive patients with pathology-proven localized pancreatic adenocarcinoma who underwent resection after 2 or more cycles of chemotherapy (with or without radiotherapy) in 19 centers from 8 countries (January 1, 2010, to December 31, 2018). Data collection was performed from February 1, 2020, to April 30, 2022, and analyses from January 1, 2022, to December 31, 2023. Median follow-up was 19 months.

Exposures

Preoperative chemotherapy (with or without radiotherapy) followed by resection.

Main Outcomes and Measures

The incidence of pCR (defined as absence of vital tumor cells in the sampled pancreas specimen after resection), its association with OS from surgery, and factors associated with pCR. Factors associated with overall survival (OS) and pCR were investigated with Cox proportional hazards and logistic regression models, respectively.

Results

Overall, 1758 patients (mean [SD] age, 64 [9] years; 879 [50.0%] male) were studied. The rate of pCR was 4.8% (n = 85), and pCR was associated with OS (hazard ratio, 0.46; 95% CI, 0.26-0.83). The 1-, 3-, and 5-year OS rates were 95%, 82%, and 63% in patients with pCR vs 80%, 46%, and 30% in patients without pCR, respectively (P < .001). Factors associated with pCR included preoperative multiagent chemotherapy other than (m)FOLFIRINOX ([modified] leucovorin calcium [folinic acid], fluorouracil, irinotecan hydrochloride, and oxaliplatin) (odds ratio [OR], 0.48; 95% CI, 0.26-0.87), preoperative conventional radiotherapy (OR, 2.03; 95% CI, 1.00-4.10), preoperative stereotactic body radiotherapy (OR, 8.91; 95% CI, 4.17-19.05), radiologic response (OR, 13.00; 95% CI, 7.02-24.08), and normal(ized) serum carbohydrate antigen 19-9 after preoperative therapy (OR, 3.76; 95% CI, 1.79-7.89).

Conclusions and Relevance

This international, retrospective cohort study found that pCR occurred in 4.8% of patients with resected localized pancreatic adenocarcinoma after preoperative chemo(radio)therapy. Although pCR does not reflect cure, it is associated with improved OS, with a doubled 5-year OS of 63% compared with 30% in patients without pCR. Factors associated with pCR related to preoperative chemo(radio)therapy regimens and anatomical and biological disease response features may have implications for treatment strategies that require validation in prospective studies because they may not universally apply to all patients with pancreatic adenocarcinoma.

Preoperative chemotherapy, radiotherapy and surgical decision-making in patients with borderline resectable and locally advanced pancreatic cancer

Surgical resection combined with systemic chemotherapy is the cornerstone of treatment for patients with localized pancreatic cancer. Upfront surgery is considered suboptimal in cases with extensive vascular involvement, which can be classified as either borderline resectable pancreatic cancer or locally advanced pancreatic cancer. In these patients, FOLFIRINOX or gemcitabine plus nab-paclitaxel chemotherapy is currently used as preoperative chemotherapy and is eventually combined with radiotherapy. Thus, more patients might reach 5-year overall survival. Patient selection for chemotherapy, radiotherapy and subsequent surgery is based on anatomical, biological and conditional parameters. Current guidelines and clinical practices vary considerably regarding preoperative chemotherapy and radiotherapy, response evaluation, and indications for surgery. In this Review, we provide an overview of the clinical evidence regarding disease staging, preoperative therapy, response evaluation and surgery in patients with borderline resectable pancreatic cancer or locally advanced pancreatic cancer. In addition, a clinical work-up is proposed based on the available evidence and guidelines. We identify knowledge gaps and outline a proposed research agenda.

Persister cell phenotypes contribute to poor patient outcomes after neoadjuvant chemotherapy in PDAC

Neoadjuvant chemotherapy can improve the survival of individuals with borderline and unresectable pancreatic ductal adenocarcinoma; however, heterogeneous responses to chemotherapy remain a significant clinical challenge. Here, we performed RNA sequencing (n = 97) and multiplexed immunofluorescence (n = 122) on chemo-naive and postchemotherapy (post-CTX) resected patient samples (chemoradiotherapy excluded) to define the impact of neoadjuvant chemotherapy. Transcriptome analysis combined with high-resolution mapping of whole-tissue sections identified GATA6 (classical), KRT17 (basal-like) and cytochrome P450 3A (CYP3A) coexpressing cells that were preferentially enriched in post-CTX resected samples. The persistence of GATA6hi and KRT17hi cells post-CTX was significantly associated with poor survival after mFOLFIRINOX (mFFX), but not gemcitabine (GEM), treatment. Analysis of organoid models derived from chemo-naive and post-CTX samples demonstrated that CYP3A expression is a predictor of chemotherapy response and that CYP3A-expressing drug detoxification pathways can metabolize the prodrug irinotecan, a constituent of mFFX. These findings identify CYP3A-expressing drug-tolerant cell phenotypes in residual disease that may ultimately inform adjuvant treatment selection.

Tailoring Adjuvant Chemotherapy to Biologic Response Following Neoadjuvant Chemotherapy Impacts Overall Survival in Pancreatic Cancer

BACKGROUND

The role of postoperative chemotherapy in patients with resected pancreatic cancer who receive neoadjuvant treatment is unknown. Clinicians use changes in CA19-9 and histopathologic scores to assess treatment response. We sought to investigate if CA19-9 normalization in response to NAT can help guide the need for postoperative treatment.

METHODS

Patients with elevated baseline CA19-9 (CA19-9 > 37U/mL) who received NAT followed by surgery between 2011 and 2019 were retrospectively reviewed. Treatment response was determined by CA19-9 normalization following NAT and histopathologic scoring. The role of postoperative chemotherapy was analyzed in light of CA19-9 normalization and histopathologic response.

RESULTS

We identified and included 345 patients. Following NAT, CA19-9 normalization was observed in 125 patients (36.2%). CA19-9 normalization was associated with a favorable histopathologic response (41.6% vs 23.2%, p < 0.001) and a lower ypT (p < 0.001) and ypN stage (p = 0.003). Receipt of adjuvant chemotherapy was associated with improved overall survival in patients in whom CA19-9 did not normalize following NAT (26.8 vs 16.4 months, p = 0.008). In patients who received 5FU-based NAT and in whom CA19-9 did not normalize, receipt of 5FU-based adjuvant chemotherapy was associated with improved OS (p = 0.014).

CONCLUSION

CA19-9 normalization in response to NAT was associated with favorable outcomes and can serve as a biomarker for treatment response. In patients where CA19-9 did not normalize, receipt of postoperative chemotherapy was associated with improved OS. These patients also benefited from additional 5FU-based postoperative chemotherapy following 5FU-based NAT.

Targeted therapy for pancreatic ductal adenocarcinoma: Mechanisms and clinical study

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive and lethal malignancy with a high rate of recurrence and a dismal 5-year survival rate. Contributing to the poor prognosis of PDAC is the lack of early detection, a complex network of signaling pathways and molecular mechanisms, a dense and desmoplastic stroma, and an immunosuppressive tumor microenvironment. A recent shift toward a neoadjuvant approach to treating PDAC has been sparked by the numerous benefits neoadjuvant therapy (NAT) has to offer compared with upfront surgery. However, certain aspects of NAT against PDAC, including the optimal regimen, the use of radiotherapy, and the selection of patients that would benefit from NAT, have yet to be fully elucidated. This review describes the major signaling pathways and molecular mechanisms involved in PDAC initiation and progression in addition to the immunosuppressive tumor microenvironment of PDAC. We then review current guidelines, ongoing research, and future research directions on the use of NAT based on randomized clinical trials and other studies. Finally, the current use of and research regarding targeted therapy for PDAC are examined. This review bridges the molecular understanding of PDAC with its clinical significance, development of novel therapies, and shifting directions in treatment paradigm.

Neoadjuvant therapy for pancreatic cancer

Patients with localized pancreatic ductal adenocarcinoma (PDAC) are best treated with surgical resection of the primary tumour and systemic chemotherapy, which provides considerably longer overall survival (OS) durations than either modality alone. Regardless, most patients will have disease relapse owing to micrometastatic disease. Although currently a matter of some debate, considerable research interest has been focused on the role of neoadjuvant therapy for all forms of resectable PDAC. Whilst adjuvant combination chemotherapy remains the standard of care for patients with resectable PDAC, neoadjuvant chemotherapy seems to improve OS without necessarily increasing the resection rate in those with borderline-resectable disease. Furthermore, around 20% of patients with unresectable non-metastatic PDAC might undergo resection following 4-6 months of induction combination chemotherapy with or without radiotherapy, even in the absence of a clear radiological response, leading to improved OS outcomes in this group. Distinct molecular and biological responses to different types of therapies need to be better understood in order to enable the optimal sequencing of specific treatment modalities to further improve OS. In this Review, we describe current treatment strategies for the various clinical stages of PDAC and discuss developments that are likely to determine the optimal sequence of multimodality therapies by integrating the fundamental clinical and molecular features of the cancer.

Cancer-cell-derived sialylated IgG as a novel biomarker for predicting poor pathological response to neoadjuvant therapy and prognosis in pancreatic cancer

BACKGROUND

Neoadjuvant therapy (NAT) is increasingly applied in pancreatic ductal adenocarcinoma (PDAC); however, accurate prediction of therapeutic response to NAT remains a pressing clinical challenge. Cancer-cell-derived sialylated immunoglobulin G (SIA-IgG) was previously identified as a prognostic biomarker in PDAC. This study aims to explore whether SIA-IgG expression in treatment-naïve fine needle aspirate (FNA) biopsy specimens could predict the pathological response (PR) to NAT for PDAC.

METHODS

Endoscopic ultrasonography-guided FNA biopsy specimens prior to NAT were prospectively obtained from 72 patients with PDAC at the Johns Hopkins Hospital. SIA-IgG expression of PDAC specimens was assessed by immunohistochemistry. Associations between SIA-IgG expression and PR, as well as patient prognosis, were analyzed. A second cohort enrolling surgically resected primary tumor specimens from 79 patients with PDAC was used to validate the prognostic value of SIA-IgG expression.

RESULTS

SIA-IgG was expressed in 58.3% of treatment-naïve FNA biopsies. Positive SIA-IgG expression at diagnosis was associated with unfavorable PR and can serve as an independent predictor of PR. The sensitivity and specificity of SIA-IgG expression in FNA specimens in predicting an unfavorable PR were 63.9% and 80.6%, respectively. Both positive SIA-IgG expression in treatment-naïve FNA specimens and high SIA-IgG expression in surgically resected primary tumor specimens were significantly associated with shorter survival.

CONCLUSIONS

Assessment of SIA-IgG on FNA specimens prior to NAT may help predict PR for PDAC. Additionally, SIA-IgG expression in treatment-naïve FNA specimens and surgically resected primary tumor specimens were predictive of the prognosis for PDAC.