DOTA-based plectin-1 targeted contrast agent enables detection of pancreatic cancer in human tissue

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive and lethal malignancy with extremely poor patient survival rates. A key reason for the poor prognosis is the lack of effective diagnostic tools to detect the disease at curable, premetastatic stages. Tumor surgical resection is PDAC first-line treatment, however distinguishing between cancerous and healthy tissue with current imaging tools remains a challenge. In this work, we report a DOTA-based fluorescent probe targeting plectin-1 for imaging PDAC with high specificity. To enable heterogeneous functionalization of the DOTA-core with multiple targeting peptide units and the fluorophore, a novel, fully clickable synthetic route that proceeds in one-pot was developed. Extensive validation of the probe set the stage for PDAC detection in mice and human tissue. Altogether, these findings may pave the way for improved clinical understanding and early detection of PDAC progression as well as more accurate resection criteria.

Extensive preclinical validation of combined RMC-4550 and LY3214996 supports clinical investigation for KRAS mutant pancreatic cancer

Over 90% of pancreatic cancers present mutations in KRAS, one of the most common oncogenic drivers overall. Currently, most KRAS mutant isoforms cannot be targeted directly. Moreover, targeting single RAS downstream effectors induces adaptive resistance mechanisms. We report here on the combined inhibition of SHP2, upstream of KRAS, using the allosteric inhibitor RMC-4550 and of ERK, downstream of KRAS, using LY3214996. This combination shows synergistic anti-cancer activity in vitro, superior disruption of the MAPK pathway, and increased apoptosis induction compared with single-agent treatments. In vivo, we demonstrate good tolerability and efficacy of the combination, with significant tumor regression in multiple pancreatic ductal adenocarcinoma (PDAC) mouse models. Finally, we show evidence that ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) can be used to assess early drug responses in animal models. Based on these results, we will investigate this drug combination in the SHP2 and ERK inhibition in pancreatic cancer (SHERPA; ClinicalTrials.gov: NCT04916236) clinical trial, enrolling patients with KRAS-mutant PDAC.

Bcl3 Couples Cancer Stem Cell Enrichment With Pancreatic Cancer Molecular Subtypes

BACKGROUND & AIMS

The existence of different subtypes of pancreatic ductal adenocarcinoma (PDAC) and their correlation with patient outcome have shifted the emphasis on patient classification for better decision-making algorithms and personalized therapy. The contribution of mechanisms regulating the cancer stem cell (CSC) population in different subtypes remains unknown.

METHODS

Using RNA-seq, we identified B-cell CLL/lymphoma 3 (BCL3), an atypical nf-κb signaling member, as differing in pancreatic CSCs. To determine the biological consequences of BCL3 silencing in vivo and in vitro, we generated bcl3-deficient preclinical mouse models as well as murine cell lines and correlated our findings with human cell lines, PDX models, and 2 independent patient cohorts. We assessed the correlation of bcl3 expression pattern with clinical parameters and subtypes.

RESULTS

Bcl3 was significantly down-regulated in human CSCs. Recapitulating this phenotype in preclinical mouse models of PDAC via BCL3 genetic knockout enhanced tumor burden, metastasis, epithelial to mesenchymal transition, and reduced overall survival. Fluorescence-activated cell sorting analyses, together with oxygen consumption, sphere formation, and tumorigenicity assays, all indicated that BCL3 loss resulted in CSC compartment expansion promoting cellular dedifferentiation. Overexpression of BCL3 in human PDXs diminished tumor growth by significantly reducing the CSC population and promoting differentiation. Human PDACs with low BCL3 expression correlated with increased metastasis, and BCL3-negative tumors correlated with lower survival and nonclassical subtypes.

CONCLUSIONS

We demonstrate that bcl3 impacts pancreatic carcinogenesis by restraining CSC expansion and by curtailing an aggressive and metastatic tumor burden in PDAC across species. Levels of BCL3 expression are a useful stratification marker for predicting subtype characterization in PDAC, thereby allowing for personalized therapeutic approaches.

Precision Therapy of Pancreatic Cancer: From Bench to Bedside

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC), with a mortality rate of 94% and a 5-year-survival rate of only 8%, is one of the deadliest cancer entities worldwide, and early diagnostic methods as well as effective therapies are urgently needed.

SUMMARY

This review summarizes current clinical procedure and recent developments of oncological therapy in the palliative setting of metastatic PDAC. It further gives examples of successful, as well as failed, targeted therapy approaches and finally discusses promising ongoing research into the decade-old question of the "undruggability" of KRAS.

KEY MESSAGES

Bench-driven concepts change the clinical landscape from "one size fits all" towards precision medicine. With growing insight into the molecular mechanisms of pancreatic cancer the era of targeted therapy in PDAC is gaining a new momentum.

Variants That Affect Function of Calcium Channel TRPV6 Are Associated With Early-Onset Chronic Pancreatitis

BACKGROUND & AIMS

Changes in pancreatic calcium levels affect secretion and might be involved in development of chronic pancreatitis (CP). We investigated the association of CP with the transient receptor potential cation channel subfamily V member 6 gene (TRPV6), which encodes a Ca²⁺-selective ion channel, in an international cohort of patients and in mice.

METHODS

We performed whole-exome DNA sequencing from a patient with idiopathic CP and from his parents, who did not have CP. We validated our findings by sequencing DNA from 300 patients with CP (not associated with alcohol consumption) and 1070 persons from the general population in Japan (control individuals). In replication studies, we sequenced DNA from patients with early-onset CP (20 years or younger) not associated with alcohol consumption from France (n = 470) and Germany (n = 410). We expressed TRPV6 variants in HEK293 cells and measured their activity using Ca²⁺ imaging assays. CP was induced by repeated injections of cerulein in TRPV6^mut/mut mice.

RESULTS

We identified the variants c.629C>T (p.A210V) and c.970G>A (p.D324N) in TRPV6 in the index patient. Variants that affected function of the TRPV6 product were found in 13 of 300 patients (4.3%) and 1 of 1070 control individuals (0.1%) from Japan (odds ratio [OR], 48.4; 95% confidence interval [CI], 6.3-371.7; P = 2.4 × 10^-8). Twelve of 124 patients (9.7%) with early-onset CP had such variants. In the replication set from Europe, 18 patients with CP (2.0%) carried variants that affected the function of the TRPV6 product compared with 0 control individuals (P = 6.2 × 10^-8). Variants that did not affect the function of the TRPV6 product (p.I223T and p.D324N) were overrepresented in Japanese patients vs control individuals (OR, 10.9; 95% CI, 4.5-25.9; P = 7.4 × 10^-9 for p.I223T and P = .01 for p.D324N), whereas the p.L299Q was overrepresented in European patients vs control individuals (OR, 3.0; 95% CI, 1.9-4.8; P = 1.2 × 10^-5). TRPV6^mut/mut mice given cerulein developed more severe pancreatitis than control mice, as shown by increased levels of pancreatic enzymes, histologic alterations, and pancreatic fibrosis.

CONCLUSIONS

We found that patients with early-onset CP not associated with alcohol consumption carry variants in TRPV6 that affect the function of its product, perhaps by altering Ca²⁺ balance in pancreatic cells. TRPV6 regulates Ca²⁺ homeostasis and pancreatic inflammation.

Levels of the Autophagy-Related 5 Protein Affect Progression and Metastasis of Pancreatic Tumors in Mice

BACKGROUND AND AIMS

Cells in pancreatic ductal adenocarcinoma (PDAC) undergo autophagy, but its effects vary with tumor stage and genetic factors. We investigated the consequences of varying levels of the autophagy related 5 (Atg5) protein on pancreatic tumor formation and progression.

METHODS

We generated mice that express oncogenic Kras in primary pancreatic cancer cells and have homozygous disruption of Atg5 (A5;Kras) or heterozygous disruption of Atg5 (A5^+/-;Kras), and compared them with mice with only oncogenic Kras (controls). Pancreata were analyzed by histology and immunohistochemistry. Primary tumor cells were isolated and used to perform transcriptome, metabolome, intracellular calcium, extracellular cathepsin activity, and cell migration and invasion analyses. The cells were injected into wild-type littermates, and orthotopic tumor growth and metastasis were monitored. Atg5 was knocked down in pancreatic cancer cell lines using small hairpin RNAs; cell migration and invasion were measured, and cells were injected into wild-type littermates. PDAC samples were obtained from independent cohorts of patients and protein levels were measured on immunoblot and immunohistochemistry; we tested the correlation of protein levels with metastasis and patient survival times.

RESULTS

A5^+/-;Kras mice, with reduced Atg5 levels, developed more tumors and metastases, than control mice, whereas A5;Kras mice did not develop any tumors. Cultured A5^+/-;Kras primary tumor cells were resistant to induction and inhibition of autophagy, had altered mitochondrial morphology, compromised mitochondrial function, changes in intracellular Ca²⁺ oscillations, and increased activity of extracellular cathepsin L and D. The tumors that formed in A5^+/-;Kras mice contained greater numbers of type 2 macrophages than control mice, and primary A5^+/-;Kras tumor cells had up-regulated expression of cytokines that regulate macrophage chemoattraction and differentiation into M2 macrophage. Knockdown of Atg5 in pancreatic cancer cell lines increased their migratory and invasive capabilities, and formation of metastases following injection into mice. In human PDAC samples, lower levels of ATG5 associated with tumor metastasis and shorter survival time.

CONCLUSIONS

In mice that express oncogenic Kras in pancreatic cells, heterozygous disruption of Atg5 and reduced protein levels promotes tumor development, whereas homozygous disruption of Atg5 blocks tumorigenesis. Therapeutic strategies to alter autophagy in PDAC should consider the effects of ATG5 levels to avoid the expansion of resistant and highly aggressive cells.