Impact of tumor growth rate during preceding treatment on tumor response to nivolumab or irinotecan in advanced gastric cancer

Background

Nivolumab (NIVO) and irinotecan (IRI) are standard treatments for refractory advanced gastric cancer (AGC); however, it is unclear which drug should be administered first or in which cases. The tumor growth rate (TGR) during preceding treatment is reported to be associated with tumor response in metastatic colorectal cancer patients treated with regorafenib or trifluridine/tipiracil, suggesting that TGR may be useful for drug selection. Therefore, we evaluated the association between TGR during preceding treatment and the tumor response to NIVO or IRI.

Patients and methods

We retrospectively evaluated consecutive AGC patients treated with NIVO or IRI and divided them into slow-growing (Slow) and rapid-growing (Rapid) groups according to TGR and the presence or absence of new lesions (NL+/NL−, respectively) during preceding treatment (Slow group: NL− with low TGR <0.30%/day; Rapid group: NL+ or high TGR ≥0.30%/day).

Results

A total of 117 patients (Rapid/Slow groups, 72/45; NIVO/IRI groups, 32/85) were eligible. All baseline characteristics except peritoneal metastases were similar between patients treated with NIVO and IRI in the Rapid and Slow groups. The response rate was significantly higher in patients treated with NIVO compared with IRI [31%/3%; odds ratio (OR), 13.8; P = 0.01; adjusted OR, 52; P = 0.002] in the Slow group, but there was no difference between patients treated with NIVO and IRI (5%/8%; OR, 0.68; P = 0.73; adjusted OR, 0.94; P = 0.96) in the Rapid group. Disease control rate, progression-free survival, and overall survival were consistent with these results.

Conclusions

Our findings suggest that NIVO treatment is a more favorable option for patients with slow-growing tumors, and NIVO and IRI are similarly recommended for patients with rapid-growing tumors in refractory AGC. TGR and NL emergence during preceding treatment may be helpful for drug selection and warrant further investigation.

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NIVO and IRI are standard treatments for refractory AGC, although it is unclear which should be administered first.

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TGR may be useful for drug selection, therefore we evaluated the association between TGR and the tumor response to NIVO or IRI.

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In the Slow group, the response rate (RR) was significantly higher in patients treated with NIVO compared with IRI.

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In the Rapid group, there was no significant difference in RR between the NIVO and IRI groups.

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TGR and NL emergence during preceding treatment may be useful for drug selection.

Pathological Features of Complete Atrioventricular Block in Dogs with Lymphocytic Myocarditis

The cardiac conduction system was examined histologically in 12 canine cases of lymphocytic myocarditis with complete atrioventricular (AV) block. Histological analysis showed active myocarditis characterized by intense infiltration of mononuclear cells, primarily lymphoid, associated with degeneration and necrosis of the adjacent cardiomyocytes. Additionally, there was healing or healed myocarditis manifested by disappearance of cardiomyocytes and replacement fibrosis. This destructive inflammatory process of lymphocytic myocarditis involved the whole of the AV conduction system, resulting in loss and deletion of the conduction fibres, as well as the myocardium of all chambers. Such total or subtotal destruction of the AV conduction system caused by the inflammatory changes was thought to have set the stage for blocking AV conduction of cardiac impulses, but the aetiology of the lymphocytic myocarditis was not elucidated.

Spermatogonial Nature of the Germ Cell Component of Canine Testicular Mixed Germ Cell-Sex Cord Stromal Tumours

The present study has characterized the germ cell component of canine testicular mixed germ cell-sex cord stromal tumours (MGSCTs) by examining the histological nature and histochemical and immunohistochemical features using gonocytic and spermatogonial cellular markers, c-Kit, placental alkaline phosphatase (PLAP), protein gene product 9.5 (PGP9.5), Sal-like protein 4 (SALL4), and the periodic acid-Schiff (PAS) reaction. Histologically, all 45 examples of MGSCTs were classified as spermatocytic seminomas (SSs) and Sertoli cell tumours in combination. The germ cell component of all MGSCTs was negative by PAS staining. Immunohistochemically, PLAP immunoreactivity was lacking in the germ cell component of all MGSCTs, which is not consistent with a gonocytic origin. The germ cell component was positive for PGP9.5 and SALL4 in all MGSCTs and positive for c-Kit in 53% of MGSCTs, which is consistent with the phenotype of spermatogonia. Furthermore, the germ cell component in 71% of MGSCTs had moderate immunoreactivity for SALL4, which is suggestive of a spermatogonial phenotype. Conversely, 29% of cases had a minor population of germ cells showing strong SALL4 immunoreactivity, suggesting a phenotype similar to prespermatogonia. The results suggest that the germ cell component of canine MGSCTs is morphologically classified as SS, with the majority of cases showing the spermatogonial phenotype and some cases containing a small population of prespermatogonia.

Improvement of hepatocyte recovery from rat liver subjected to 1-hour warm ischemic injury by using citrate phosphate dextrose added to euro-collins perfusion solution

Warm ischemia (WI)-related injury interferes with recovery of primary hepatocyte after collagenase digestion of surgically resected or non-heart-beating donor livers as human cell sources. We speculated that digestion is impaired due to reduced microcirculation, caused by microembolism after WI. We sought to improve hepatocyte recovery after WI using a rat model. Anesthetized 9-week-old male Sprague-Dawley rats underwent a midline abdominal incision to insert a 22-gauge cannula into the portal vein. WI was initiated by ligating both the cannula and the hepatic artery. We compared Euro-Collins (EC) perfusion solution with 2 anticoagulants-heparin or citrate phosphate dextrose (CPD)-versus ethylene glycol tetraacetic acid (EGTA) combined with Ca(2+)- and Mg(2+)-free Hank's solution (CM-free Hank's solution). Use of CM-free Hank's solution yielded only 0.75 ± 0.15 × 10(8) and 0.82 ± 0.20 × 10(8) cells at 30 and 60 minutes WI respectively. However, CPD, but not heparin, added to the EC solution produced the best cell recovery (CPD: 2.15 ± 0.38 × 10(8); heparin: 1.63 ± 0.31 × 10(8)). During macroscopic observation, CPD added to EC solution also demonstrated best blood flushing. CPD added to EC solution achieved greater hepatocyte recovery than CM-free Hank's solution by restoring microcirculation during flushing of blood from liver tissue subjected to WI.

Tumour endothelial marker-1 is expressed in canine Haemangiopericytomas

The aim of this study was to characterize immunohistochemically 18 cases of canine haemangiopericytoma (CHP) using two new candidate markers for pericytes, tumour endothelial marker (TEM)-1 and new glue (NG)-2, as well as the conventional mesenchymal cellular markers, vimentin, α-smooth muscle actin (α-SMA), desmin and von Willebrand factor (vWF). Because pericytes may have the same origin as endothelial or smooth muscle cells or the same differentiation potential as myofibroblasts, 17 cases of leiomyosarcoma (LMS), 20 cases of haemangiosarcoma (HS) and three cases of myofibroblastic sarcoma (MFS) were also examined. Expression of TEM-1 by >10% of the neoplastic population was observed in 94.4% (17/18) of haemangiopericytomas, 23.5% (4/17) of LMSs, 30.0% (6/20) of HSs and 66.7% (2/3) of MFSs. NG-2 expression by >10% of the neoplastic population was observed in 16.7% (3/18) of haemangiopericytomas, 52.9% (9/17) of LMSs, 0% (0/20) of HSs and 33.3% (1/3) of MFSs. Vimentin was expressed by all of tumours. In haemangiopericytoma, the incidence of positive immunoreactivity in >10% of the neoplastic population was 5.6% (1/18) for both α-SMA and desmin and 0% (0/18) for vWF. Considering the phenotypic features of cells expressing TEM-1, CHPs are thought to originate from immature vascular mural cells sharing their phenotype with myofibroblasts. NG-2 expression may be a phenotype of smooth muscle cells rather than pericytes in dogs.

Histopathological and immunohistochemical evaluation of malignant potential in canine aortic body tumours

In order to verify the malignant potential of aortic body tumours (ABTs) in dogs, 13 cases of canine ABT were studied histopathologically and immunohistochemically. The cases were divided into two groups according to the presence or absence of metastases to other organs at necropsy examination (metastasis group [n = 9] and non-metastasis group [n = 4]). The mean tumour weight:body weight ratio (TW:BW; g/kg) in the metastasis group (9.3 ± 6.7) was significantly higher than that in the non-metastasis group (1.5 ± 1.7) (P <0.05). In both groups, the neoplastic cells had malignant features including pleomorphism, anisocytosis and anisokaryosis, and mononuclear giant cells were present, showing invasion through the capsule and into the vascular lumen and other adjacent tissues. The mitotic index (MI), mean nuclear area (NA) for size value and coefficient of variation of the nuclear area (CVNA) for anisonucleosis did not differ significantly between the two groups. These findings show that anaplastic characteristics are present regardless of the tumour size or the presence or absence of metastases, suggesting that these tumours are generally malignant or potentially malignant. Immunohistochemical analysis using neuroendocrine markers including neuron-specific enolase, chromogranin A and S100 revealed no obvious differences in labelling intensity of neoplastic cells related to the presence or absence of metastases or associated with the mean TW:BW, MI, NA or CVNA value, indicating that immunohistochemistry has no practical value for determining the tumour grade of canine ABTs.

The effect of pimobendan on left atrial pressure in dogs with mitral valve regurgitation

BACKGROUND

The effects of pimobendan on left atrial pressure (LAP) in dogs with mitral valve disease (MR) have not been documented in a quantitative manner.

OBJECTIVE

The objective was to document and study the short-term effects of pimobendan on LAP and echocardiographic parameters in MR dogs.

ANIMALS

Eight healthy Beagle dogs weighing 10.0-14.7 kg (3 males and 5 females; aged 2 years) were used.

METHODS

Experimental, cross-over, and interventional study. Dogs with surgically induced MR received pimobendan at either 0.25 mg/kg or 0.50 mg/kg p.o. q12h for 7 days and then, after a 7-day wash-out period, the other dosage. LAP was measured for 30 minutes at baseline and again on days 1, 2, 4, and 7 of pimobendan administration.

RESULTS

Mean LAP was significantly decreased after the administration of 0.25 mg/kg (15.81 ± 5.44 mmHg to 12.67 ± 5.71 mmHg, P < .001) and 0.50 mg/kg (15.76 ± 5.45 mmHg to 10.77 ± 5.23 mmHg, P < .001). Also, the 0.50 mg/kg group led to a significantly lower LAP (P < .01) compared with the 0.25 mg/kg group. Significant reduction was seen for the first time 4 days after the administration of 0.25 mg/kg and a day after the administration of 0.50 mg/kg.

CONCLUSIONS AND CLINICAL IMPORTANCE

Pimobendan decreased LAP in a dose-dependent manner in dogs with acute MR caused by experimental chordal rupture. This study did not evaluate adverse effects of high-dose pimobendan, and additional studies in clinical patients are warranted.

Phase I dose escalation and pharmacokinetics study of intravenous aflibercept plus irinotecan, 5-fluorouracil, and folinic acid (FOLFIRI) in patients with metastatic colorectal cancer

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Background: Aflibercept (AF), a recombinant fusion protein, is a potent inhibitor of vascular endothelial growth factor. This study assessed the safety, dose limiting toxicities (DLTs), recommended dose (RD), and the pharmacokinetics (PK) of AF in combination with FOLFIRI.

Methods: This was an open-label, sequential-cohort, dose-escalation study of intravenous AF administered every 2 weeks, in combination with FOLFIRI (fixed doses) in patients (pts) with metastatic colorectal cancer (MCRC). Two dose levels (DL) of AF (2 and 4 mg/kg) were set, and 3-6 pts were to be recruited in each DL. DLTs were to be evaluated in the first 2 cycles. RD was defined as the highest AF dose at which <33% of all evaluable pts experienced DLTs. After establishment of RD, 10 additional pts were treated at RD. PK of AF, irinotecan, SN38, and 5-FU were studied in cycle 1.

Results: 16 pts (3 at 2 mg/kg and 13 at 4 mg/kg) with MCRC were treated (M/F, 10/6; median age, 57.0 [47-69]; and ECOG PS 0/1, 9/7), and all had received prior chemotherapies. A total of 131 cycles of AF + FOLFIRI were administered at the two DLs of AF (2 and 4 mg/kg). No DLT was observed. The most common all-causality grade 3/4 adverse events were neutropenia (75.0 %) including one febrile neutropenia after DLT evaluation period and hypertension (25.0%). There was no major safety issue at the RD. Response rate and progression free survival at RD (N=13 pts) was 7.8% and 7.6 month, respectively.

Conclusions: RD was determined as 4 mg/kg in this first clinical study of AF in Japanese pts with MCRC. The combination of AF (4 mg/kg) and FOLFIRI was well tolerated in line with results of prior overseas studies. The PK results in Japanese patients showed similar tendency to those reported in patients from other regions of the world.

[Table: see text]

Complete Atrioventricular Block Associated with Lymphocytic Myocarditis of the Atrioventricular Node in Two Young Adult Dogs

A histological investigation of the atrioventricular (AV) conduction system was performed in two young adult dogs with complete AV block. In both cases, infiltration of lymphocytes and plasma cells into the AV node and loss and disappearance of the conduction fibres were observed. Such inflammatory lesions of the AV conduction system were associated with complete AV block. The aetiology of these changes and the cause of its location at the AV node were not elucidated.

Application of the RTOG recursive partitioning analysis classification to brain metastases from colorectal cancer

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Background: Colorectal cancer infrequently causes brain metastases (BMs). Recently, the incidence of BMs from colorectal cancer (CRC) has been reported to be increasing as 3 % of all metastatic CRCs, especially in patients (pts) with lung metastases (LMs). The RTOG previously developed three prognostic classes for BMs using a recursive partitioning analysis (RPA) classification, including Karnofsky performance status, controlled primary tumor, extracranial metastases, and an age. However, the relevance of this classification for CRC remains unclear, because only a few CRC pts were included in the RTOG database. The present studies retrospectively evaluate the usefulness of RPA classification for BMs from CRC. Methods: The subjects were consecutive 290 metastatic CRCs without symptomatic BMs who treated with any chemotherapy initiated in our institution between 2002 and 2005. The treatment of BMs, including whole brain radiation therapy (WBRT), surgery, and stereotactic radiosurgery (SRS), were indicated for pts whose life expectancy was considered to exceed 3 months (M). Results: BMs were detected in 20 pts out of 133 (15%) with LMs at base line, with a median follow-up time of 17.7 M. In the remaining 157 pts, BMs were found in 3 pts out of 41(7%) who had developed LMs during follow-up and 2 pts out of 116 (2%) without LMs. In total, overall incidence of BMs was 9% (25/ 290). Median duration from the diagnosis of LMs to BMs was 12 M (range: 4.4–33.6). According to RPA, the 25 pts with BMs were classified into Class I 0 (0%), Class II 12 (48%) and Class III 13 (52%). Treatments for BMs were performed to all pts of Class II, and to 6 pts (46%) of Class III. Median overall survivals from detecting BMs were Class II 9.7 M and Class III 3.0 M (logrank test; p=0.02). In the 18 pts treated for BMs, median BMs progression-free survival of Class II and Class III were 3.0 M and 3.1 M. Conclusions: It is suggested that the incidence of BMs from CRC is more common than previously reported. Overall survivals for BMs reproduce the results from RPA classification.

No significant financial relationships to disclose.

A Histological Study of the Cardiac Conduction System in Canine Cases of Mitral Valve Endocardiosis with Complete Atrioventricular Block

The cardiac conduction system was examined histologically in four canine cases of endocardiosis of the mitral valve (MV) with complete atrioventricular (AV) block. In all cases, moderate to severe reduction of the conduction fibres due to fibrous or fibro-fatty replacement was observed in the penetrating and branching portions of the AV bundle. In addition, degenerative and fibrotic lesions were commonly seen at the upper portions of the left and right bundle branches. These changes in the AV conduction system were associated with marked degeneration and fibrosis of the base of the central fibrous body and the upper part of the ventricular septum. The degenerative and sclerotic changes of the AV junctional region, affecting the AV bundle and bundle branches, were qualitatively similar to those in age-matched control dogs, but were more severe. It is possible that the pathological process occurred as a result of ageing and may have been exaggerated or accelerated by the abnormal mechanical forces created by excessive motion of the prolapsed MV and the long-term haemodynamic stresses of mitral regurgitation, resulting in interruption of the AV conduction system to produce complete AV block. Conduction abnormalities represent a possible complication in some canine cases of MV endocardiosis.

The Anatomical Basis of Complete Atrioventricular Block in Cats with Hypertrophic Cardiomyopathy

The cardiac conduction system was examined histologically in 13 feline cases of hypertrophic cardiomyopathy (HCM) with complete atrioventricular (AV) block. Marked degeneration and fibrous replacement of the AV conduction system were consistently observed in the combined regions of the branching portion of the AV bundle and the upper portion of the left bundle branch. These changes were associated with extensive fibrosis of the central fibrous body and endocardial and myocardial fibrosis in the upper border of the ventricular septum. Chondrometaplastic lesions or osseous lesions, or both, present in the base of the central fibrous body, compressed the underlying penetrating or branching (or both) portions of the AV bundle, causing apparent reduction of the conduction fibres. The pathological process and the nature and predilection sites of the lesions resembled those associated with ageing in human patients with complete AV block. It is possible that the pathological process in the cats was fundamentally related to the normal ageing phenomenon and may have been exacerbated by mechanical forces created by the cardiac hypertrophy associated with HCM.

Surgical management of a double-chambered right ventricle and chylothorax in a Labrador retriever

A 22-month-old, male Labrador retriever was presented with anorexia, dyspnoea, and fainting. The dog was diagnosed with a double-chambered right ventricle and tricuspid valve dysplasia using echocardiography and cardiac catheterisation. A marked bilateral pleural effusion was also present and chemical analysis of the fluid confirmed the diagnosis of chylothorax. Using echocardiography, a pressure gradient of 87.1 mmHg was found between the proximal and distal chambers of the double-chambered right ventricle. Initiation of cardiopulmonary bypass allowed the anomalous muscle bundle that divided the right ventricle into two chambers to be resected via a right ventriculotomy. The fainting completely resolved postoperatively, and this treatment seemed quite effective in the reduction of pressure overload ascribable to ejection disturbance. Because the tricuspid dysplasia was not corrected in the first operation, the postoperative chyle effusion was reduced but did not cease. A combination of thoracic duct ligation and passive pleuroperitoneal shunting was effective in the resolution of the chyle effusion.