Hyperprogression Under Immune Checkpoint-Based Immunotherapy—Current Understanding, The Role of PD-1/PD-L1 Tumour-Intrinsic Signalling, Future Directions and a Potential Large Animal Model

Immune evasion is a major challenge for the development of successful cancer treatments. One of the known mechanisms is the expression of immune checkpoints (ICs)—proteins regulating the immune cells activation. The advent of immunotherapy using monoclonal antibodies (mAbs) to block the immune checkpoint receptor-ligand interaction brought about a landslide improvement in the treatment responses, leading to a prompt approval of such therapeutics. In recent years, it was discovered that a subset of patients receiving IC blockade treatment experienced a previously unknown pattern of treatment response called hyperprogression (HP), characterised by rapid deterioration on initialisation of the therapy. HP represents an urgent issue for clinicians and drug developers, while posing questions about the adequacy of the current clinical trial process. Here, we briefly summarise the state of knowledge and propose new directions for research into HP mechanisms, focusing on tumour-intrinsic signalling of IC proteins malignantly expressed by cancer. We also discuss the potential role of spontaneously occurring canine cancer in the assessment of immunotherapeutics, which can provide the missing link between murine and human studies

Paraneoplastic leukocytosis in a dog following liposarcoma resection

A 10-year-old, female, neutered cocker spaniel presented for surgical debulking of an axillary and cranial thoracic wall liposarcoma. Pre-surgical blood analysis demonstrated anaemia (packed cell volume 17%), leukocytosis (white blood cell count 43.95 × 10 9/L) and thrombocytopenia (15 × 10 9/L), with platelet loss secondary to chronic intra-lesional haemorrhage or immune-mediated destruction, and concomitant Staphylococcus pseudintermedius urinary tract infection. A blood transfusion and antibiotics were administered before surgery. Within 48 hours after surgery, an extreme leukocytosis (white blood cell count 170 × 10 9/L), involving a severe left shift neutrophilia (95 × 10 9/L) was observed; this resolved within 10 days. Serum granulocyte-colony stimulating factor levels were similar to controls. The extreme leukocytosis was suspected to be related to a paraneoplastic leukaemoid reaction combined with an expected postoperative mild leukocytosis. Further investigation into the pathophysiology underlying similar cases is required. One month after surgery, all haematological abnormalities had normalised, and metronomic chemotherapy with chlorambucil commenced.</p

Four dimensional CT excretory Urography as an Accurate Technique for Diagnosis of Canine Ureteral Ectopia

Computed tomographic (CT) excretory urography is commonly used to investigate canine ureteral ectopia (UE). Modern technology allows time-resolved CT imaging (four-dimensional CT excretory urography [4D-CTEU]) over a distance exceeding the detector collimation. Objectives of this prospective, observational, diagnostic accuracy study were to evaluate the diagnostic accuracy of CT excretory urography (CTEU) and 4D-CTEU for UE in dogs with lower urinary tract signs, assess the influence of pelvis positioning, and to determine the significance of the ureterovesical junction (UVJ) angle for UE diagnosis. Thirty-six dogs, with a total of 42 normotopic ureters, 27 intramural ectopic ureters, and three extramural ectopic ureters, underwent CTEU and 4D-CTEU with randomized pelvis positioning. Randomized CTEU and 4D-CTEU studies were scored by two observers for ureteral papilla location and murality on a grading scheme. Interobserver agreement, sensitivity, and specificity for ureter topia status and diagnosis were calculated. Computed tomographic excretory urography showed moderate interobserver agreement for the left ureter and perfect for the right ureter, whereas 4D-CTEU showed bilateral nearly perfect agreement between both observers. When comparing CTEU versus confirmed diagnosis, there was a sensitivity and specificity of 73% and 90.2%, respectively, whereas 4D-CTEU showed a sensitivity and specificity of 97% and 94.6%, respectively. An obtuse UVJ angle is significantly more commonly observed in ectopic intramural than normotopic ureters and is significantly associated with increased diagnostic confidence of UE. The use of a wedge to angle the pelvis did not increase the diagnostic confidence in determining ureteral opening position. Four-dimensional CT excretory urography is an accurate and reliable diagnostic technique to investigate UE as cause of urinary incontinence in dogs that is slightly superior to CTEU

Candidate circulating microRNA biomarkers in dogs with chronic pancreatitis:MicroRNA BIOMARKERS CANINE PANCREATITIS

BACKGROUND: Pancreatitis is an important cause of disease and death in dogs. Available circulating biomarkers are not sufficiently sensitive and specific for a definitive diagnosis.HYPOTHESIS: Circulating microRNAs would be differentially expressed in dogs with chronic pancreatitis and could have potential as diagnostic biomarkers.ANIMALS: Healthy controls (n = 19) and dogs with naturally occurring pancreatitis (n = 17).METHODS: A retrospective case-control study. Dogs with pancreatitis were included if they satisfied diagnostic criteria for pancreatitis as adjudicated by 3 experts. MicroRNA was extracted from stored serum samples and sequenced. Reads were mapped to mature microRNA sequences in the canine, mouse, and human genomes. Differentially expressed microRNAs were identified and the potential mechanistic relevance explored using Qiagen Ingenuity Pathway Analysis (IPA).RESULTS: Reads mapping to 196 mature microRNA sequences were detected. Eight circulating microRNAs were significantly differentially expressed in dogs with pancreatitis (≥2-fold change and false discovery rate &lt;0.05). Four of these mapped to the canine genome (cfa-miR-221, cfa-miR-222, cfa-miR-23a, and cfa-miR-205). Three mapped to the murine genome (mmu-miR-484, mmu-miR-6240, mmu-miR-101a-3p) and 1 to the human genome (hsa-miR-1290). Expression in dogs with pancreatitis was higher for 7 microRNAs and lower for mmu-miR-101a-3p. Qiagen IPA demonstrated a number of the differently expressed microRNAs are involved in a common pancreatic inflammatory pathway.CONCLUSIONS: The significantly differentially expressed microRNAs represent promising candidates for further validation as diagnostic biomarkers for canine pancreatitis.</p

Comparative characterization of two monoclonal antibodies targeting canine PD-1

Monoclonal antibodies targeting immune checkpoints have revolutionizedoncology. Yet, the effectiveness of these treatments varies significantly amongpatients, and they are associated with unexpected adverse events, includinghyperprogression. The murine research model used in drug development fails torecapitulate both the functional human immune system and the populationheterogeneity. Hence, a novel model is urgently needed to study theconsequences of immune checkpoint blockade. Dogs appear to be uniquelysuited for this role. Approximately 1 in 4 companion dogs dies from cancer, yetno antibodies are commercially available for use in veterinary oncology. Here wecharacterize two novel antibodies that bind canine PD-1 with sub-nanomolaraffinity as measured by SPR. Both antibodies block the clinically crucial PD-1/PDL1 interaction in a competitive ELISA assay. Additionally, the antibodies weretested with a broad range of assays including Western Blot, ELISA, flowcytometry, immunofluorescence and immunohistochemistry. The antibodiesappear to bind two distinct epitopes as predicted by molecular modeling andpeptide phage display. Our study provides new tools for canine oncologyresearch and a potential veterinary therapeutic