Splenic Hemangiosarcoma Case Study: Sam Fisher

Splenic Hemangiosarcoma Case Study: Sam Fisher

After FidoCure® enabled treatment, Sam exceeded the 5-7  month median survival time for splenic hemangiosarcoma by living over one year beyond diagnosis.

Introduction

Hemangiosarcoma (HSA) is a highly malignant tumor  arising from endothelial cells. These cells are derived  from bone marrow precursors, classified as angiogenesis,  inflammation or adipogenesis subtypes, and can develop  lesions in any type of tissue containing vascular structures. HSA is a very common tumor in dogs representing  2-5% of all cancerous lesions and more than 50% of all  splenic malignancies in the species. Although all breeds  can be affected, male dogs from large breeds, such as  German Shepherds, Golden Retrievers and Labrador  Retrievers, particularly middle-aged to older dogs (~10  years-old), are more commonly affected.  

HSA can develop in any tissue or structure of the body,  with the most common sites being the spleen, heart,  liver, skin and subcutaneous tissues. Visceral HSA  is more common than dermal HSA and is associated  with a poorer prognosis due the high rate of metastasis.  Unfortunately, metastases commonly occur in the liver, omentum, and/or lungs, but they can occur anywhere  throughout the body.  Dogs with HSA have nonspecific clinical signs usually  associated with primary tumor development and internal  hemorrhage which is common with visceral lesions due  to tumor rupture. These cases often present to a veterinary emergency service for marked lethargy or collapse,  and emergency surgery may follow after identifying a  hemoabdomen or mass on abdominal ultrasound.

Histopathologic examination is the standard method for  definitive diagnosis. Just after diagnosis, clinical staging  diagnostics are often performed to evaluate the extent  of disease and appropriate treatment options. CBC,  biochemistry, coagulation profiles, urinalysis, three-view  thoracic radiographs, abdominal ultrasound and echocardiography are usually recommended.

The standard treatment for dogs with HSA is surgical  removal of the primary lesion. Systemic therapy is usually  recommended after surgery due to the high metastatic  rate and aggressive nature of HSA. Doxorubicin is the  most widely used chemotherapy agent for treatment of  canine HSA. Doxorubicin may be used as a single agent or  incorporated into a number of combinatorial protocols.  Metronomic cyclophosphamide or chlorambucil with or  without NSAIDs are also commonly considered systemic  therapeutic options for canine HSA

Despite surgical and medical treatment options, the  prognosis for visceral hemangiosarcoma remains poor.  Surgical removal followed by systemic chemotherapy  leads to a median survival time of 5-7 months with only  about 10% of patients surviving to one year. More recent  molecular data and therapeutic options may offer a  potential improvement in patient survival or prognostic guidance by incorporating both tumor biology and  behavior with genomic indications.

History, Initial Assessment  and Surgery

Sam Fisher, a 10-year-old male neutered Labrador  Retriever, was presented to the Cornell University Veterinary Specialists in June 2019 due to sudden and marked  lethargy. An abdominal ultrasound identified the presence of a hemoabdomen and Sam’s family elected to  pursue emergency surgery. Surgery revealed a ruptured  splenic mass which was surgically removed via splenectomy. Given the potential for neoplasia, a liver biopsy was  performed from an adjacent liver lobe that was subjectively, grossly irregular in appearance.  The entire spleen and liver biopsy were submitted for  histopathologic evaluation. Histopathology of the splenic  lesion was consistent with a diagnosis of hemangiosarcoma. Moderate anisocytosis and anisokaryosis was  noted with multifocal necrosis and hemorrhage as well  as a mitotic count of 6. The liver biopsy revealed mild  hepatocellular vacuolar degeneration, but no evidence  of neoplasia. Subsequently, Sam’s family was referred to  a veterinary medical oncologist at The Veterinary Cancer  Center for additional staging and treatment options.

Post-Operative Evaluation  and Treatment Plan

On July 9, 2019, after discussion of available treatment  options, Sam’s family elected to start metronomic therapy with cyclophosphamide (16 mg PO SID) and deramaxx (37.5 mg PO SID). In addition to chemotherapy,  Sam’s family decided to pursue FidoCure®  genomic  diagnostics on the splenic tumor tissue.

FidoCure®  Analysis

The tumor tissue was sent for genomic (DNA) and transcriptomic (RNA) sequencing and in August 2019, the  findings were reported. Genomic analysis revealed alterations of BRAF and N-RAS.

N-RAS is a single member of the RAS family of proteins  involved primarily in regulating cell division. N-RAS  belongs to a class of genes known as oncogenes that play  important roles in cell division, cell differentiation and  apoptosis. Activating N-RAS mutations lock the enzyme  in an active state causing increased cellular proliferation  via hyper-activating MAPK and PI3K signaling pathways.

Somatic mutations in the N-RAS gene are involved in  the development of several types of cancer. The Q61R  mutation, as in Sam’s case, has been widely investigated  in many human cancers, such as: malignant melanoma,  carcinomas, hematopoietic and lymphoid tumors . In  dogs, the Q61R mutation has been identified in hemangiosarcoma, oral melanoma and oral acanthomatous  ameloblastoma. In both species, this mutation is often  associated with generalized therapeutic resistance,  however ongoing trials are exploring the benefit of both  upstream and downstream effector protein targeted  inhibition.

BRAF is a gene which codes for the BRAF protein kinase  which is part of the MAPK/ERK cellular signaling pathway.  In humans, the aligned position (V168L) to Sam’s mutation  (V105L), has been shown as a driver in lung cancer. This  mutation leads to over phosphorylation of downstream  proteins (MEK) which in turn can propagate unregulated  cell growth and proliferation. Treatment with tyrosine  kinase inhibitors (TKIs) that target MEK and BRAF have  shown improved efficacy over traditional approaches in  some human malignancies harboring these mutations.

Findings based on RNA (transcriptomic) expression  profiling were consistent with overexpression of CDK4,  JAK1, KDR, KIT, MEK1/2, and mTOR. CDK4 is the gene encoding cyclin dependent kinase 4. This family of  proteins plays a critical role in cell cycle regulation, and  dysregulation of this pathway has been identified as a driver for increased cell proliferation.

JAK1 is a gene that encodes a JAK1 protein member of a  protein kinase family, activating and recruiting targets  such as STAT proteins. The JAK-STAT pathway plays a role  in cellular proliferation and tumorigenesis.

KDR is one of the subtypes of the family of vascular endothelial growth factor receptors (VEGFR). These receptors  primarily bind a ligand called vascular endothelial growth  factor (VEGF) leading to angiogenesis (the development  of new blood vessels), stimulation and activation of  PLC-gamma, and downstream signaling pathways such  as PI3K/AKT. Upregulation of KDR and VEGF may lead to  an increase in cell cycle progression and a therapeutic  opportunity for drugs that inhibit angiogenesis.

KIT, or stem cell growth factor receptor, is a receptor  tyrosine kinase involved in a number of cellular proliferation and growth processes. KIT activation results in  increased intracellular signaling through several pathways including PI3K, MAPK and STAT, ultimately leading  to cell proliferation and survival. c-KIT has been implicated in the pathogenesis of multiple human neoplastic diseases, and it’s mutations lead to a constitutively  activated KIT product in the absence of ligand. Activating  c-KIT mutations and aberrant KIT expression have also  been described in canine cutaneous mast cell tumors.  c-KIT mutations have been identified in the juxtamembrane domain, in exon 11, of canine MCTs and consist of  internal tandem duplications and deletions in 30% to  50% of all intermediate- to high-grade mast cell tumors.

MEK is a gene that codes for the protein MEK1. This is  a downstream protein that belongs to the MAPK/ERK  signaling pathway. Overexpression of this gene may result  in tumor cell growth, proliferation, and survival. Targeted  inhibitors that prevent overactivity and dysregulated  signaling of this protein may be successful approaches  to treating MEK driven cancers.

MTOR encodes a serine-threonine kinase protein which  is a downstream component of the PI3K cellular signaling pathway, a pathway important in regulating the cell  cycle. The activity of mTOR has been implicated in human  and canine cancer because of potentiating signals for  neovascularization and cell growth. Upregulation of mTOR  and the PI3K pathway promotes cell cycle progression  and survival.

FidoCure®  Treatment

The FidoCure®  Precision Medicine Report including genomic and transcriptomic analysis arrived on  August 8, 2019, and indicated potential benefit from the  incorporation of targeted therapy into Sam’s medical  approach. After discussing the rationale of combinatorial approaches, the following targeted therapies were  prescribed by Sam’s veterinary oncologist: • Imatinib 10 mg/kg/day (465 mg PO q 24 hours) • Rapamycin (mTOR inhibitor) 0.1 mg/kg/day (4.5 mg PO q 24 hours) Beginning in August 2019, these medications were  administered orally by Sam’s family at home. Sam  continued metronomic therapy (combination of cyclophosphamide and Deramaxx) until this treatment was  discontinued in October 2019. Rapamycin was subsequently discontinued in November 2019 due to gastrointestinal side effects. Overt metastatic disease was  not definitively diagnosed, although a restaging abdominal ultrasound in December 2019 did reveal two small  nodules in the mesentery. Sam’s family elected to monitor these lesions via imaging and continue therapy with  imatinib. Sam was able to tolerate therapy well and  maintain a high quality of life until his passing in July 2020.

Conclusion  

Sam retained a high quality of life for thirteen  months after incorporating FidoCure® enabled diagnostics and treatment. By living over one year beyond diagnosis of this  incredibly challenging cancer, Sam surpassed the  commonly reported median survival time (5-7  months) for dogs with hemangiosarcoma treated  with splenectomy and chemotherapy. Additionally,  after incorporating FidoCure® enabled diagnostics  and treatment, Sam and his family were able to have  additional, quality time together.

What Sam’s Vet Said

“ With the FidoCure®  treatment, we were able to not only control Sam’s cancer  for some time but also do so with minimal side effects. Sam was able to enjoy  a good quality of life for about a year which is longer than what is historically  reported for those treated with injectable chemotherapy."                                                                                            — Dr. Dorothy Jackson Girimonte, DVM, DACVIM

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