Limited Clinical Efficacy with Potential Adverse Events in a Pilot Study of Autologous Adoptive Cell Therapy in Canine Oral Malignant Melanoma

Adoptive cell therapy (ACT) has been studied in several human and canine cancers with some promising clinical outcomes but not in canine oral malignant melanoma (OMM). Our manuscript aimed to explore one kind of ACT, the ex vivo-expanded autologous immune cell infusion in canine OMM, as this tumor remains a treatment dilemma. The study recruited dogs with histopathological diagnoses of oral malignant melanoma, generated their peripheral blood mononuclear cells, expanded them into predominantly non-B non-T cells via stimulations of IL-15, IL-2, and IL-21, and then re-infused the cells into tumor-bearing dogs. Ten dogs were enrolled; three dogs did not report any adverse events; three had a mildly altered appetite; one had a mildly increased liver index, while the other three developed suspected anaphylaxis at different levels. The median progression-free interval was 49 days. Dogs with progressive disease during treatment had a shorter survival. This pilot study indicates limited efficacy with potential adverse events of this ACT. Most recruited patients were in a later stage and had macroscopic disease, which might affect the treatment efficacy. Further exploration of this cell therapy in an adjuvant setting, with adequate protocol modification and standardization, could still be considered.

Relationship of microsatellite instability to mismatch repair deficiency in malignant tumors of dogs

BACKGROUND

Microsatellite instability (MSI) is a type of genomic instability caused by mismatch repair deficiency (dMMR) in tumors. Studies on dMMR/MSI are limited, and the relationship between dMMR and MSI is unknown in tumors of dogs.

OBJECTIVES

We aimed to identify the frequency of dMMR/MSI by tumor type and evaluate the relationship between dMMR and MSI in tumors of dogs.

ANIMALS

In total, 101 dogs with 11 types of malignant tumors were included.

METHODS

We extracted DNA from fresh normal and tumor tissues. Twelve microsatellite loci from both normal and tumor DNA were amplified by PCR and detected by capillary electrophoresis. Each microsatellite (MS) was defined as MSI if a difference in product size between the tumor and normal DNA was detected. The dMMR was evaluated by immunohistochemistry with formalin-fixed paraffin-embedded tumor tissues. Next, we confirmed whether dMMR induces MSI by serial passaging of MMR gene knockout cell lines for 3 months.

RESULTS

Microsatellite instability was detected frequently in oral malignant melanoma. The number of MSI-positive markers was higher in cases with dMMR than in those with proficient MMR (P < .0001). Statistical analysis indicated that the occurrence of MSI in FH2305 might have relevance to dMMR. Furthermore, MSI occurred in dMMR cell lines 3 months after passaging.

CONCLUSIONS AND CLINICAL IMPORTANCE

Microsatellite instability and dMMR more frequently were found in oral malignant melanoma than in other tumors, and dMMR has relevance to MSI in both clinical cases and cell lines.

Curative Intent Surgery of Oral Malignant Melanoma and Regional Lymph Node Biopsy Assessment in 25 Dogs: 2006-2017

Medical records were searched for dogs that had received curative intent surgery for oral malignant melanoma and ipsilateral excisional regional lymph node biopsy. Twenty-seven dogs were operated on and 25 dogs of these dogs met the inclusion criteria of signalment, post-excision margin status, presence of metastasis for each biopsied lymphocentrum, survival time post-excision, presence of recurrence or metastasis at follow-up or at death/euthanasia, location of the primary tumor, and any postoperative adjuvant treatment. These 25 dogs had complete tumor excision with tumor-free margins and 19 (76%) had postoperative adjuvant therapy. Median survival time after excision for the dogs in this study was 335.5 days. Results of this study support previous work that documents prolonged survival time following complete excision of oral malignant melanoma with tumor-free surgical margins in dogs. Additionally, 4 dogs (16%) had histologically confirmed regional lymph node metastasis at the time of definitive surgery.

Difference in outcome between curative intent vs marginal excision as a first treatment in dogs with oral malignant melanoma and the impact of adjuvant CSPG4-DNA electrovaccination: A retrospective study on 155 cases

Canine oral malignant melanoma is locally invasive and highly metastatic. At present, the best option for local control is en bloc excision followed by radiation if excision margins are incomplete. Adjuvantly, the role of chemotherapy is dubious while immunotherapy appears encouraging. This retrospective study evaluated 155 dogs with oral malignant melanomas (24 stage I, 54 stage II, 66 stage III and 11 stage IV) managed in a single institution. The aim was to evaluate the differences in median survival time (MST) and disease-free interval (DFI) between dogs which, at presentation, were treated surgically with a curative intent (group 1) vs those marginally excised only (group 2). MST in group 1 was longer than in group 2 (594 vs 458 days), but no significant difference was found (P = .57); a statistical difference was, however, found for DFI (232 vs 183 days, P = .008). In the subpopulation of vaccinated dogs, the impact of adjuvant anti-CSPG4 DNA electrovaccination was then evaluated (curative intent, group 3, vs marginal, group 4); a significant difference for both MST (1333 vs 470 days, respectively, P = .03) and DFI (324 vs 184 days, respectively, P = .008) was found. Progressive disease was significantly more common in dogs undergoing marginal excision than curative intent excision for both the overall population (P = .03) and the vaccinated dogs (P = .02). This study pointed out that, after staging, wide excision together with adjuvant immunotherapy was an effective approach for canine oral malignant melanoma.

Mismatch repair deficiency in canine neoplasms

The DNA mismatch repair (MMR) system preserves genomic stability by identifying and repairing mismatched nucleotides in the DNA replication process. The dysfunction of the MMR system, also known as mismatch repair deficiency (dMMR), is implicated as a predictive biomarker for the efficacy of immune checkpoint blockade therapy regardless of the tumor type in humans. This study aimed to evaluate the immunolabeling of MMR proteins in canine tumors and to identify the types of tumors having dMMR. First, we performed immunohistochemistry in 8 different canine tumors (oral malignant melanoma, high-to-intermediate grade lymphoma, mast cell tumor, malignant mammary gland tumor, urothelial carcinoma, hepatocellular carcinoma, osteosarcoma, and hemangiosarcoma) with 15 samples each to analyze the immunolabeling of canine mismatch repair proteins (MSH2, MSH6, and MLH1) using anti-human monoclonal antibodies. We found that more than half of canine oral malignant melanoma (60%) and hepatocellular carcinoma (53%) samples and fewer of the other canine tumors had loss of immunolabeling in ≥1 MMR protein (ie, evidence of defective MMR proteins, based on the definition of dMMR in the humans). Antibodies against human MSH2, MSH6, and MLH1 were cross-reactive with the corresponding canine protein as confirmed using MMR gene knockout canine cell lines. Further studies are required to investigate the clinical outcomes in canine spontaneous tumors with dMMR to determine the potential for immune checkpoint blockade therapy for these tumor types.

Oral malignant melanoma

Malignant melanoma in the head and neck area is rare. The incidence of oral malignant melanomas of the head and neck is approximately four per 10 million populations per year. They are derived from epidermal melanocytes and are most frequently seen on the palate and maxillary gingiva. They are asymptomatic initially but become painful with progress and enlargement. Later, they are associated with ulceration, bleeding, mobility of tooth, paresthesia and ill-fitting prosthesis. The diagnosis is often delayed due to silent growth and development of the lesion. Oral malignant melanomas are associated with poor prognosis due to their invasive and metastasizing tendencies. This case report is presented to emphasize the role of a dentist in identifying the pigmented lesions of the oral cavity.

Prevalence of malignant melanoma in anatomical sites of the oral cavity: A meta-analysis

Oral malignant melanoma (OMM) is a very rare disease entity accounting <1% of all other melanomas. Till date, no comprehensive meta-analysis has been conducted regarding the prevalence of malignant melanoma in the oral cavity. Therefore, the present meta-analysis was conducted to update on the prevalence of malignant melanoma in anatomical sites of the oral cavity. Literature search was performed to congregate reports of last 10 years using databases, such as PubMed and ScienceDirect. The search strings used were "palate," "buccal," "gingiva," "gum," "maxillary," "mandibular," "lip," "tongue," "melanoma," "oral melanoma," "malignant melanoma," "prognosis," "risk factors," "noncutaneous" and "diagnosis" of OMM by combining terms using the Boolean operators. MedCalc 16.4.3 software was used for the analysis. "Random effects model" was used in the analysis due to significant heterogeneity in the studies. Proportion method was used to analyze the prevalence. Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed to report the analysis. Out of 130 studies screened, 19 were included in the meta-analysis and a total of 1323 patients were included. The median age of the patients was found to be 61.87 ± 7.78 years (confidence interval 53.8-67 years). All the screened studies showed significant heterogeneity in gender as well as tumor sites (P < 0.0001). Palate (34.29%) was the most commonly affected site in OMM patients. Overall, the results of the meta-analysis suggest that palate is the most prevalent site in OMM. Furthermore, OMM is high in patients between the fifth and sixth decade of life with a male predominance.

Oral malignant melanoma: An aggressive clinical entity - Report of a rare case with review of literature

Melanomais one of the most dreaded and aggressive neoplasms, being derived from epidermal melanocytes. The majority of melanomas are seen to involve the skin, and primary mucosal melanomas account for less than 1% of all melanomas. Oral malignant melanomas (OMM) are asymptomatic at the initial presentation, but later they become painful with growth and expansion. In the late stages, the patient may present with ulceration, bleeding, tooth mobility, paresthesia, ill-fitting prosthesis, and delayed healing of the extraction sockets. Diagnosis is often delayed due to asymptomatic clinical presentation, with silent progression of the lesion. OMM are associated with poor prognosis due to their invasive and metastasizing tendencies. The condition has poor survival rates, and metastatic melanomas show even worse prognosis. The 5-year survival rate for OMM ranges 4.5–29%, with 18.5 months being the mean survival rate. The tumor is best managed by wide surgical resection; however, consideration should also be made for adjunctive therapies such as chemotherapy, immunotherapy, and radiotherapy. Recurrences may be seen even 10–15 years after the primary therapy. This paper aims to present an interesting report of aggressive OMM in a 50-year-old male patient and emphasizes the role of dental professionals in maintaining a high degree of vigilance for the pigmented lesions of the oral cavity. Pigmented lesions of uncertain origin should be routinely biopsied to rule out malignancy. Early diagnosis of this dreadful entity entails thorough history taking, physical examination, and radiographic features coupled with histopathology.

Oral malignant melanoma: a rare case with unusual clinical presentation

Primary Oral malignant melanoma is a rare tumor with an indigent prognosis. This is a case report of 47-year-old Sudanese female diagnosed as Oral malignant melanoma of the mandible with an unusual pattern of growth and clinical presentation. Furthermore, a possibility of intraosseous origin is suggested.

Malignant melanoma of gingiva: Report of a rare case

According to the World Health Organization, oral malignant melanoma (OMM) is a rare disease, accounting for only 0.8% of all melanomas, 8% of head and neck melanomas, and up to 0.5% of all oral malignancies. OMM presents as a pigmented lesion with asymmetrical borders, irregular surface characteristics, and a distinct color. Melanoma-associated pigmented lesion of the oral cavity does not possess clinical specificity and frequently divert the clinical diagnosis; hence, differential diagnosis becomes mandatory. Furthermore, the unpredictable pathophysiological behavior and delayed detection, contributes for poor prognosis of the disease. As a result, the 5 years survival rate is only 10–25%. Commonly OMM is seen in maxillary gingiva of males. However, we report a rare case of a middle-aged female having pigmentations and growth over mandibular gingiva.

Oral malignant melanoma: A case report with review of literature

Oral mucosal melanoma is a rare malignancy with the tendency to metastasize and locally invade tissues more readily than other malignant tumor of the oral cavity. It occurs approximately four times more frequently in the oral mucosa of the upper jaw usually on the palate or alveolar gingiva. The chameleonic presentation of malignant melanoma, its asymptomatic condition, rarity of the lesion, poor prognosis and the necessity of a highly specialized treatment are factors that should be seriously considered by the involved health care provider. Herein we report a rare and interesting case of oral malignant melanoma of the maxillary anterior gingiva, which was clinically and histopathologically diagnosed with a brief review of literature, has been discussed.

Oral malignant melanoma: A report of two cases with BRAF molecular analysis

Primary oral malignant melanoma is a rare condition, accounting for 1.3–1.4% of all melanomas, usually presenting with an aggressive clinical behavior. The present study reports the clinicopathological findings of two cases of oral malignant melanoma and discusses the epidemiology, diagnosis and current therapeutic approaches for this uncommon condition. In the first case the patient presented with a pigmented lesion located on the lower mucosal lip. The patient showed no nodal metastases and therefore, underwent a wedge resection. After seven months, the patient presented with neck lymph nodes and multiple visceral metastases. Molecular analysis of BRAF, using a pyrosequencing approach, revealed the presence of BRAF V600E mutation. The patient developed multiple visceral metastases, but refused treatment and was lost to follow-up. In the second case, no BRAF V600E mutation was found, but the patient exhibited a pigmented patch in the lower gingival mucosa, which was excised by surgical treatment. The patient was followed up by an oncologist, but did not undergo an additional therapy and is currently alive with no evidence of visceral metastases at one year following the diagnosis.

Pigmented lesion with characteristics of malignancy: a case report

Pigmentations of the oral mucosa include a range of lesions or conditions that manifest as changes in the color of oral tissues; these changes may show melanocytic activity. A melanotic macule is a small, well-circumscribed melanocytic benign lesion. It can occur on the lips and intraorally and ranges in color from brown to black. Microscopically, it is characterized by elevated levels of melanin production by basal melanocytes, which appear normal in terms of number, morphology, and distribution. A 48-year-old woman sought treatment for a pigmented lesion that had been present for 4 months. Intraoral examination revealed a non-homogenous brownish spot (measuring 0.7 cm) with irregular borders on the left side of the soft palate. Since the lesion had an atypical clinical appearance, melanocytic nevus, oral melanoacanthoma, and oral malignant melanoma were considered in differential diagnoses. After an incisional biopsy, the lesion was diagnosed as a melanotic macule. Due to their varying clinical appearance, benign pigmented lesions can be mistaken for malignant tumors, especially when the lesions exhibit similar coloration, symmetry, and borders. Through this report on a case with atypical clinical characteristics, we aim to reinforce the ubiquitous nature of oral pigmented lesions, and the importance of employing different approaches to diagnosing these lesions.

Oral malignant melanoma: A silent killer?

Oral malignant melanomas are extremely rare lesions and occur commonly in the maxillary gingiva more frequently on the palate with fewer incidences in the mandibular gingiva. Though these lesions are biologically aggressive, they often go unnoticed since they are clinically asymptomatic in the early stages and usually present merely as a hyperpigmented patch on the gingival surface. These lesions if diagnosed at an early in situ stage are potentially curable and definitely have a better prognosis, but unfortunately as they are clinically asymptomatic, it results in delayed diagnosis thus making the prognosis extremely poor. This paper presents the case of a patient who visited our department with the complaint of darkened patches on the gums and his concern was purely aesthetic. There were no symptoms associated with the hyperpigmented lesions and hence the patient did not approach us earlier. When the lesions grew larger and were unsightly, the patient has seeked dental advice. Histopathologic investigation confirmed the diagnosis as ‘Oral Malignant Melanoma’. Though aggressive therapy was instilled immediately, unfortunately, the patient succumbed to death within a few months after diagnosis as the lesion was highly invasive. Due to the biologically aggressive but clinically silent nature of progression of the lesion, the importance of maintaining a high index of suspicion and early detection and diagnosis for any pigmented gingival lesions cannot be overemphasised. Diagnosis must be based on thorough detailed history and valid histologic evidence.

Malignant melanoma of the mandibular gingiva

Oral malignant melanoma is an infrequent neoplasia making up less than 1% of all melanomas, which exhibits much more aggressive behavior than those found on the skin. We present an aggressive case of oral malignant melanoma located on the mandibular gingiva in a 24-year-old male patient, who developed metastases to not only the regional lymph nodes but also the lungs and liver. The advanced stage of the disease contraindicated any surgical intervention and palliative chemotherapy was planned.