The Efficacy and Safety of Treating Acquired MET Resistance Through Combinations of Parent and MET Tyrosine Kinase Inhibitors in Patients With Metastatic Oncogene-Driven NSCLC

Introduction

Acquired MET gene amplification, MET exon 14 skip mutations, or MET fusions can emerge as resistance mechanisms to tyrosine kinase inhibitors (TKIs) in patients with lung cancer. The efficacy and safety of combining MET TKIs (such as crizotinib, capmatinib, or tepotinib) with parent TKIs to target acquired MET resistance are not well characterized.

Methods

Multi-institutional retrospective chart review identified 83 patients with metastatic oncogene-driven NSCLC that were separated into the following two pairwise matched cohorts: (1) MET cohort (n = 41)-patients with acquired MET resistance continuing their parent TKI with a MET TKI added or (2) Chemotherapy cohort (n = 42)-patients without any actionable resistance continuing their parent TKI with a platinum-pemetrexed added. Clinicopathologic features, radiographic response (by means of Response Evaluation Criteria in Solid Tumors version 1.1), survival outcomes, adverse events (AEs) (by means of Common Terminology Criteria for Adverse Events version 5.0), and genomic data were collected. Survival outcomes were assessed using Kaplan-Meier methods. Multivariate modeling adjusted for lines of therapy, brain metastases, TP53 mutations, and oligometastatic disease.

Results

Within the MET cohort, median age was 56 years (range: 36-83 y). Most patients were never smokers (28 of 41, 68.3%). Baseline brain metastases were common (21 of 41, 51%). The most common oncogenes in the MET cohort were EGFR (30 of 41, 73.2%), ALK (seven of 41, 17.1%), and ROS1 (two of 41, 4.9%). Co-occurring TP53 mutations (32 of 41, 78%) were frequent. Acquired MET alterations included MET gene amplification (37 of 41, 90%), MET exon 14 mutations (two of 41, 5%), and MET gene fusions (two of 41, 5%). After multivariate adjustment, the objective response rate (ORR) was higher in the MET cohort versus the chemotherapy cohort (ORR: 69.2% versus 20%, p < 0.001). Within the MET cohort, MET gene copy number (≥10 versus 6-10) did not affect radiographic response (54.5% versus 68.4%, p = 0.698). There was no difference in ORR on the basis of MET TKI used (F [2, 36] = 0.021, p = 0.978). There was no difference in progression-free survival (5 versus 6 mo; hazard ratio = 0.64; 95% confidence interval: 0.34-1.23, p = 0.18) or overall survival (13 versus 11 mo; hazard ratio = 0.75; 95% confidence interval: 0.42-1.35, p = 0.34) between the MET and chemotherapy cohorts. In the MET cohort, dose reductions for MET TKI-related toxicities were common (17 of 41, 41.4%) but less frequent for parent TKIs (two of 41, 5%). Grade 3 AEs were not significant between crizotinib, capmatinib, and tepotinib (p = 0.3). The discontinuation rate of MET TKIs was 17% with no significant differences between MET TKIs (p = 0.315). Among pre- and post-treatment biopsies (n = 17) in the MET cohort, the most common next-generation sequencing findings were loss of MET gene amplification (15 of 17, 88.2%), MET on-target mutations (seven of 17, 41.2%), new Ras-Raf-MAPK alterations (three of 17, 17.6%), and EGFR gene amplification (two of 17, 11.7%).

Conclusions

The efficacy and safety of combining MET TKIs (crizotinib, capmatinib, or tepotinib) with parent TKIs for acquired MET resistance are efficacious. Radiographic response and AEs did not differ significantly on the basis of the underlying MET TKI used. Loss of MET gene amplification, development of MET on-target mutations, Ras-Raf-MAPK alterations, and EGFR gene amplification were molecular patterns found on progression with dual parent and MET TKI combinations.

Colonic gastrointestinal stromal tumor (GIST) presenting with colocolonic intussusception: A rare case report

An 8-year-old spayed female British bulldog was presented with vomiting, hyporexia, and large-bowel diarrhea. Abdominal ultrasound revealed a focal colonic mass with an intussusception located immediately oral to the mass. The intussusception encompassed the ascending and transverse colon and was non-reducible. Colonic resection and anastomosis were completed to include the intussusception and colonic mass. Histopathological examination of the mass demonstrated a spindle cell neoplasm arising within the muscular wall of the intussuscepted segment that obliterated normal architecture. Mild-to-moderate cytoplasmic immunoreactivity of the tumor cell population for CD117 and smooth muscle actin was consistent with a diagnosis of a gastrointestinal stromal tumor. The dog described herein remains alive and free of progressive disease at the time of writing. Key clinical message: The entire gastrointestinal tract should be evaluated in any animal with gastrointestinal symptoms. A gastrointestinal stromal tumor remains a plausible differential diagnosis, regardless of the intestinal segment affected, and tumorassociated intussusception is a rare but urgent clinical finding.

Unilateral primary carcinoma of the kidney with central nervous system invasion and vertebral lysis in a cat

Case summary

A young adult female spayed domestic shorthair cat presented for acute hindlimb weakness and anorexia with a 1-month history of lethargy, hyporexia and weight loss. A mass was palpable in the caudolateral abdomen and the left hindlimb was diffusely edematous. Abdominal ultrasound showed hydronephrosis of the left kidney with suspected hydroureter and heterogeneous tissue in the dorsal abdomen. CT evaluation confirmed a mass extending from the left kidney through the lumbar musculature with hydronephrosis, aortic attenuation, caudal vena caval thrombosis and lysis of vertebrae 4 and 5. Fine-needle aspiration of the mass suggested squamous cell carcinoma. Owing to clinical deterioration, euthanasia was elected. At necropsy, the left kidney was firmly adhered to the lumbar region with tissue that obliterated the musculature and surrounded the aorta and vena cava. There was hydronephrosis of the left kidney. Histopathologic evaluation of the mass revealed islands of neoplastic epithelial cells separated by fibrous connective tissue and areas of gradual keratinization with rare squamous metaplasia. The histologic diagnosis was invasive carcinoma with desmoplasia and vascular invasion.

Relevance and novel information

Primary carcinomas of the kidney in cats are rare and this report documents a progression of disease not previously reported in cats. This is the second reported case of a primary carcinoma of renal origin with features of squamous cell carcinoma in a cat, and the first with lumbar and vascular invasion. This is also the first use of kidney injury molecule-1 to help investigate tumor differentiation in cats.

Vascular Disorders of Pregnancy Increase Susceptibility to Neonatal Pulmonary Hypertension in High-Altitude Populations

BACKGROUND

Preeclampsia and fetal growth restriction increase cardiopulmonary disease risk for affected offspring and occur more frequently at high-altitude (≥2500 m). Retrospective studies indicate that birth to a preeclampsia woman at high altitude increases the risk of pulmonary hypertension (PH) in later life. This prospective study asked whether preeclampsia with or without fetal growth restriction exaggerated fetal hypoxia and impaired angiogenesis in the fetal lung, leading to neonatal cardiopulmonary circulation abnormalities and neonatal or infantile PH.

METHODS AND RESULTS

We studied 79 maternal-infant pairs (39 preeclampsia, 40 controls) in Bolivia (3600-4100 m). Cord blood erythropoietin, hemoglobin, and umbilical artery and venous blood gases were measured as indices of fetal hypoxia. Maternal and cord plasma levels of angiogenic (VEGF [vascular endothelial growth factor]) and antiangiogenic (sFlt1 [soluble fms-like tyrosine kinase]) factors were determined. Postnatal echocardiography (1 week and 6-9 months) assessed pulmonary hemodynamics and PH. Preeclampsia augmented fetal hypoxia and increased the risk of PH in the neonate but not later in infancy. Pulmonary abnormalities were confined to preeclampsia cases with fetal growth restriction. Maternal and fetal plasma sFlt1 levels were higher in preeclampsia than controls and positively associated with PH.

CONCLUSIONS

The effect of preeclampsia with fetal growth restriction to increase fetal hypoxia and sFlt1 levels may impede normal development of the pulmonary circulation at high altitude, leading to adverse neonatal pulmonary vascular outcomes. Our observations highlight important temporal windows for the prevention of pulmonary vascular disease among babies born to highland residents or those with exaggerated hypoxia in utero or newborn life.

Hepatic Dicrocoelium dendriticum infection in a miniature horse

A miniature horse which died following humane seizure from an Ontario farm was emaciated with serous atrophy of fat. Autopsy revealed hepatic atrophy and moderate periportal fibrosis. Eggs and trematodes seen in the liver were identified as Dicrocoelium dendriticum. This appears to be the first reported case of infection of equids in North America with Dicrocoelium dendriticum.

Hepatic alveolar hydatid disease (Echinococcus multilocularis) in a boxer dog from southern Ontario

A 2-year-old boxer dog from southern Ontario was evaluated because of acute onset lethargy. Exploratory laparotomy revealed a hemorrhagic, destructive, liver mass. Histology, immunohistochemistry, and polymerase chain reaction confirmed Echinococcus multilocularis as the cause of the hepatic mass. This constitutes the first description of endemic E. multilocularis in Ontario.

Commentary

Veterinary pathologists working as toxicologic pathologists in academic settings fill many vital roles, such as diagnosticians, educators, and/or researchers. These individuals have spent years investigating pathology problems that mainly or exclusively focus on the reactions of cells, organs, or systems to toxic materials. Thus, academic toxicologic pathologists are uniquely suited both to help trainees understand toxicity as a cause of pathology responses and also to provide expert consultation on toxicologic pathology. Most toxicologic pathologists in academia are employed at colleges of medicine or veterinary medicine, even though specific toxicologic pathology faculty appointments are uncommon in Europe and North America. Academic toxicologic pathologists typically receive lower financial compensation than do toxicologic pathologists in industry, but academic positions generally provide alternative rewards, such as higher workplace autonomy and scheduling flexibility, professional enrichment through student interactions, and enhanced opportunities for collaborative research and advanced diagnostic investigations. Regular participation by academic toxicologic pathologists in professional training opportunities (eg, as pathology and toxicology instructors in medical and veterinary medical courses, graduate programs, and residencies) offers an important means of engendering interest and inspiring veterinarians to select toxicologic pathology and toxicology as their own areas of future expertise.

A prospective study of sheep and goat abortion using real-time polymerase chain reaction and cut point estimation shows Coxiella burnetii and Chlamydophila abortus infection concurrently with other major pathogens

From 2009 to 2011, 163 sheep and 96 goat abortion submissions were received at the Animal Health Laboratory, University of Guelph, Ontario, Canada, for gross and histologic examination, as well as real-time polymerase chain reaction (PCR) testing for Chlamydophila abortus and/or Coxiella burnetii. Additional testing included immunohistochemistry for Toxoplasma gondii and Chlamydophila spp., routine bacterial culture and selective culture for Campylobacter spp., examination of modified acid-fast–stained placenta smears, enzyme-linked immunosorbent assay testing for Chlamydophila spp., and virus isolation. The final diagnosis made for each case by individual pathologists, based on gross and histologic lesions, as well as ancillary testing, was used as a standard to determine the significance of C. abortus and C. burnetii infection. Coxiella burnetii was identified by real-time PCR in 113 of 163 (69.0%) and 72 of 96 (75%) sheep and goat abortion submissions, respectively, but was considered to be significant in causing abortion in only 11 of 113 (10%) sheep and 15 out of 72 (21%) goat submissions that tested positive. Chlamydophila abortus was identified by real-time PCR in 42 of 162 (26%) and 54 of 92 (59%) sheep and goat submissions, respectively, but was considered the cause of the abortion in 16 of 42 (38%) sheep and 34 of 54 (63%) goat submissions that tested positive. Optimal sensitivity and specificity cut points for the real-time PCR copy number for C. abortus and C. burnetii were determined using the final pathology diagnosis as the reference test.

Concentration of lipocalin region of collagen XXVII alpha 1 in the serum of dogs with hemangiosarcoma

BACKGROUND

Hemangiosarcoma (HSA) is a common malignancy of dogs with characteristic early, aggressive metastasis. Diagnosis of HSA is challenging because of lack of sensitive and specific diagnostic tests.

HYPOTHESIS

Specific proteins that are increased in serum of dogs with HSA might represent useful biomarkers of the disease.

ANIMALS

Thirty-four dogs with HSA and 42 healthy dogs from the Ontario Veterinary College Teaching Hospital.

METHODS

This case-control study compared serum proteins in dogs with HSA and healthy dogs. Proteins were separated by 2-dimensional difference gel electrophoresis and identified by liquid chromatography and tandem mass spectrometry.

RESULTS

Western blot analysis showed that serum collagen XXVII peptide concentration in serum of dogs with large metastatic HSA burdens (1,488, 231-3,754 DU; median, minimum-maximum); was, on average, 9.5-fold higher than in healthy dogs (156; 46-2,101 DU). While concentrations for dogs with osteosarcomas (678; 124-3,251 DU), lymphomas (423; 92-2,777 DU), carcinomas (1,022; 177-3,448 DU), and inflammatory disease were also increased, values were consistently lower than those for HSA. Receiver operating characteristic curves revealed an estimated area under the curve of 83% for HSA cases whereas areas for other neoplastic and nonneoplastic diseases were nondiscriminatory. Serum collagen XXVII peptide concentration before splenectomy (1,350; 1,156-1,929 DU) was reduced after tumor removal (529; 452-562 DU) and chemotherapy but increased in 2 dogs with tumor recurrence (511-945 DU; 493-650 DU).

CONCLUSIONS AND CLINICAL IMPORTANCE

Collagen XXVII peptide might be useful for diagnosis and monitoring of advanced HSA.

The 'straight to test' initiative reduces both diagnostic and treatment waiting times for colorectal cancer: outcomes after 2 years

AIM

This study aimed to determine whether a 'straight to test'(STT) strategy for 2-week wait (2 wk) referrals for suspected colorectal cancer (CRC) reduced the time to diagnosis and treatment for patients with CRC.

METHOD

Consecutive 2-week referrals for suspected CRC over a period of 2 years from February 2007 were analysed. The times to the first diagnostic test and treatment and the cancers identified were analysed for those going to STT or the outpatient clinic.

RESULTS

Of 662 patients having a 2 wk referral, 519 (78.4%) were suitable for the hospital colorectal telephone triage service, 121 (18.3%) patients went to STT and 502 (75.8%) were seen in the clinic. Of these 401 (79.8%) underwent diagnostic tests and 25 (6.2%) had CRC and in 12 (2.9%) patients other cancers were detected. In the STT group, 7 (5.8%) patients were diagnosed with CRC. The median time to first diagnostic test was 12 days (IQR 9-13) in the STT pathway, compared with 23 days (17-31) in those seen in the clinic (P < 0.0001). The median time to first treatment was 40 (32-48) days for those via STT, compared to 46 (28-55) days for those seen in the clinic (P = 0.004). A total of 162 CRC were diagnosed during the study period of whom 34 (20.9%) were 2 wk referrals (5.1% of all suspected CRC 2 wk referrals), and 14 (2.1%) other cancers were detected via this pathway.

CONCLUSION

STT speeds up the patient pathway by reducing the time to diagnosis and treatment for patients with CRC.

Prostatic Abscess in a Neutered Cat

A 6-year-old, male castrated domestic shorthair cat was presented for evaluation of lethargy, vomiting, anorexia, and constipation. Physical examination revealed an elevated body temperature and an extramural colonic mass. Abdominal ultrasonography demonstrated a hypoechoic mass measuring 2.2 cm in maximum dimension immediately caudal to the bladder. Cytological evaluation of a fine-needle aspirate confirmed the mass was a prostatic abscess. Abdominal celiotomy and prostatic omentalization were successful in resolving clinical abnormalities. Feline prostatic abscessation is a rare condition that has not been previously reported and may have a good outcome if treated early and appropriately.

Natural and experimental infection of neonatal calves with Clostridium difficile

Clostridium difficile toxins were associated with calf diarrhea in a recent retrospective study; however, no causal relationship has been prospectively investigated. This infection study tested whether the oral inoculation of neonatal calves with a toxigenic strain of C. difficile (PCR-ribotype 077) results in enteric disease.

Fourteen 6–24 h old male colostrums-fed Holstein calves, received either three doses of C. difficile (1.4 × 10⁸ ± 3.5 × 10⁸ cfu) (n = 8) or sterile culture broth (n = 6). Calves were euthanized on day 6 or after the onset of diarrhea, whichever came first. Fecal and intestinal samples were blindly cultured for C. difficile, and tested for its toxin A/B (C. difficile TOX A/B II ELISA, Techlab). PCR-ribotyping was used to compare inoculated and recovered isolates.

Diarrhea was observed in all control calves and 3/8 of inoculated calves (p = 0.03), but it did not occur in calves that tested positive for C. difficile toxins. Fecal toxins were identified only from two controls. PCR-ribotyping confirmed the presence of C. difficile PCR-ribotype 077 in samples of all inoculated calves, but not from controls. The identification of five other PCR-ribotypes in 3/8 (37.5%) and 2/6 (33.3%) of inoculated and control calves, respectively, indicated early natural infection (≤24 h of age). Five of 14 cecal samples had C. difficile (p = 0.01). In conclusion, the oral administration of C. difficile PCR-ribotype 077 to neonatal calves resulted in fecal/intestinal colonization but not in detection of toxins, or signs of enteric disease. Further studies are required to investigate the clinical relevance of C. difficile in calves.

Inflammatory aural polyp in a horse

An inflammatory aural polyp was identified in a 1-year-old standardbred filly, which presented with otorrhea and head rubbing. The polyp was removed by traction-avulsion, and the filly showed no subsequent signs of otorrhea. Aural polyps have not been reported in horses, but they are commonly seen in companion animals and humans.

Fifty ways to leave your rubber: how men in Mombasa rationalise unsafe sex

OBJECTIVE

To explore the reasons why men who have sex with sex workers in Kenya refuse to use condoms in order to develop potential interventions that might help to overcome these barriers.

METHODS

We conducted participant observations over a period of 2 months in the bars, discos, shebeens, and guesthouses of Mombasa, Kenya, where many of the sexual transactions are initiated.

RESULTS

Analysis of the participant observations revealed at least 50 reasons for not using a condom, which we grouped into six categories: condoms are not pleasurable, condoms are defective, condoms are harmful, condoms are unnecessary, condoms are too hard to use, and external forces prohibit using condoms.

CONCLUSIONS

Some of the reasons men say they do not use condoms would be difficult to affect directly. Others are the result of gaps in knowledge and have not been impacted through better communication strategies. Finally, some of the reasons for not using condoms, such as men's weaknesses, and the loss of pleasure, could possibly be addressed through the introduction of female controlled devices. However, the most important conclusion of this paper is that men who pay for sex do so because it is pleasurable and many men do not find the male condom pleasurable. Therefore, messages targeted at men who have sex with sex workers may not be 100% successful if they only emphasise the benefits of condom use as disease control.

An investigation of the etiology of a mild diarrhea observed in a group of grower/finisher pigs

An investigation into a mild diarrhea in a group of grower/finisher pigs was carried out in order to determine the etiology. A tiamulin injection and a carbadox-medicated ration were given to pens of pigs in a 2 x 2 factorial experimental design. Pens of pigs were assessed a score, based on the consistency of the feces in the pen, each week. The clinical investigation looked for the intestinal pathogens Brachyspira pilosicoli, B. hyodysenteriae, Lawsonia intracellularis, Salmonella spp., Yersinia spp., transmissible gastroenteritis virus, and rotavirus. Despite a rigorous investigation, the diarrhea was not attributed to any pathogen. A mild colitis was noted among pigs necropsied while affected with diarrhea. Improved diagnostic tools may allow a more effective response to an outbreak of mild disease, while at the same time reducing the amount of antimicrobials used in swine production.

Expression of immunoreactive glutathione S-transferases in hepatic neoplasms induced by aflatoxin B1 or 1,2-dimethylbenzanthracene in rainbow trout (Oncorhynchus mykiss)

The expression of immunoreactive glutathione S-transferase (GST) was examined in hepatic neoplasms induced in rainbow trout by aflatoxin B1 (AFB) or 1,2-dimethylbenzanthracene (DMBA). Tumors were induced in adult trout by continuous dietary exposure to 8 p.p.b. AFB1 for 12 months or embryo bath exposure to DMBA (5 p.p.m. for 24 h, 3 times with 12 h intervals between exposures). Polyclonal antiserum specific for the two major trout hepatic GST subunits in trout liver was produced by immunizing rabbits with affinity-purified trout GST. Hepatocellular, cholangiolar and mixed neoplasms as well as foci of hepatocellular alteration were examined for GST immunoreactivity by the PAP technique. The majority of lesions were GST-deficient (AFB treated, 67%; DMBA treated, 54%), whereas GST expression was induced in 21% (AFB treated) and 31% (DMBA treated) of altered hepatic foci. The GST-induced foci were consistently small (AFB treated, 0.07 +/- 0.05 mm2; DMBA treated, 0.02 +/- 0.01 mm2) and none had progressed beyond the altered focus stage. The majority of larger advanced lesions (adenomas and carcinomas) were GST deficient (AFB treated, 2.33 +/- 0.35 mm2; DMBA treated, 2.95 +/- 0.59 mm2). These studies demonstrate that induced GST expression occurs in some small populations of hepatocytes, but not in larger advanced stages of malignant progression of aflatoxin- or PAH-induced hepatic neoplasms in rainbow trout.