Oral Melanoma Research Articles

The Use of Oncept Melanoma Vaccine in Veterinary Patients: A Review of the Literature.

The Oncept melanoma vaccine is xenogeneic DNA vaccine targeting tyrosinase. It is USDA approved for treatment of stage II to III canine oral melanoma and is also used off-label for melanomas arising in other locations and in other species. While the vaccine appears safe, the published data is mixed as to whether it provides a survival benefit, and the use of the vaccine is somewhat controversial in the veterinary oncology community. In this paper, the published literature describing the use of Oncept is reviewed and evaluated.

Feasibility of using dental putty-based custom molds for high-dose-rate brachytherapy of oral mucosal melanoma

PurposeTo investigate the feasibility of using dental putty to fabricate custom molds for high-dose-rate (HDR) brachytherapy of oral mucosal melanoma. Practical guidelines of using dental putty for the custom mold fabrication are presented. MethodsDose measurements were performed using radiochromic films to understand the dosimetric characteristics of dental putty. The percentage depth dose (PDD) and profile curves were obtained using a single Co-60 source located on top of a cubic volume of the dental putty. Two custom molds were fabricated for a patient with mucosal melanoma lesions, which were spread throughout the right mandibular gingiva and soft palate regions. Furthermore, pretreatment dosimetry for both lesions was performed to evaluate the delivery quality of the resulting HDR brachytherapy plans and adjust the overall dose level. ResultsPrescribed doses for the two oral cavity regions were successfully delivered with a reasonable dose uniformity. Based on the measured single-source PDD curve, the maximum dose was observed at a depth of approximately 1 mm, which indicated steep dose gradients at depths ranging from 0 to 2 mm. Furthermore, a simulation with the measured single-source two-dimensional profile revealed that a source-to-source distance of 10 mm was appropriate to generate a uniform dose distribution at a source-to-surface distance of 5 mm. ConclusionsThe use of a custom mold was found to be feasible for HDR brachytherapy while carefully considering the source-to-surface and source-to-source distances. Pretreatment delivery verification would be necessary when a uniform dose distribution is required.

Random mucosal rotating flaps for rostral to mid maxillary defect reconstruction: 26 dogs (2000-2019).

To evaluate the feasibility and the complications following single or double random mucosal rotating (transposition or interpolation) flaps for the closure of rostral to mid maxillary defects in dogs. Medical records of dogs treated with single or double random mucosal rotating flaps after maxillectomy for oral lesions or traumatic loss of tissue, were evaluated. Clinical findings, surgery performed, outcome and postoperative complications (major and minor) were extracted. Twenty-six client-owned dogs were retrospectively included. Dogs underwent maxillectomy for canine acanthomatous ameloblastomas (9), oral squamous cell carcinomas (4), peripheral odontogenic fibromas (4), oral melanomas (3), oral fibrosarcomas (2), dentigerous cysts (2) and oral osteosarcoma (1) and trauma resulting in an oronasal fistula (1). Twenty-three dogs underwent a single transposition or interpolation flap and three dogs were treated with a double transposition flap. Postoperative complications, including dehiscence or flap necrosis, occurred in six dogs. Random mucosal rotating (transposition or interpolation) flaps are versatile when used to close rostral maxillary defects in dogs. Postoperative complications appear to be more likely when these flaps are used to close mid maxillary defects.

Chemotherapy in combination with anti-PD-1 agents as adjuvant therapy for high-risk oral mucosal melanoma.

Adjuvant therapy plays a critical role in the treatment of oral mucosal melanoma (OMM). Anti-programmed cell death-1 (PD-1) agents are recommended as front-line therapy for metastatic melanoma, but their efficacy as adjuvant therapy for high-risk OMM remains unclear. A single-center, retrospective cohort study was conducted in 193 nodular-type oral mucosal melanoma (NOMM) patients who received chemotherapy alone or in combination with high-dose interferon-α2b (HDI) or anti-PD-1 agents as adjuvant therapy. Multivariate analysis was performed to identify significant prognostic factors for the 2-year overall survival (OS) and progression-free survival (PFS). Tumor thickness, ulceration and invasion level were found to be independent prognostic factors for both 2-year OS and PFS, while T-stage was only associated with OS. The 2-year OS and PFS were 43.5% and 10.9% in patients who received only chemotherapy. In comparison, the 2-year OS was improved, albeit not significantly (47.4%; p > 0.05), and PFS was significantly improved (43.6%; p = 0.0028) in patients who received chemotherapy plus HDI; and both 2-year OS (71.0%; p = 0.0118) and PFS (53.6%; p = 0.0001) were significantly improved in patients received chemotherapy plus anti-PD-1. The serious adverse event (SAE) (p < 0.0001) and discontinued treatment due to SAE (p < 0.0001) were significantly lower in patients who received anti-PD-1 than in patients who received HDI. Invasion level and tumor thickness are independent prognostic factors for NOMM. Chemotherapy plus anti-PD-1 agents seem to be the adjuvant therapy of choice for NOMM, as it is safer and more tolerable than HDI and, more importantly, it can significantly improve the OS and PFS.

Sentinel Lymph Node Biopsy Is Feasible in Dogs with Scars from Prior Local Excision of Solid Malignancies.

Simple SummarySentinel lymph node (SLN) excision is gaining relevance in the management of various canine malignancies due to its recognized impact on staging and treatment choices. However, the technologies to perform SLN mapping are only available to a few referral centers, and there is increasing demand for secondary nodal staging after prior tumor excision at the primary care institution. This retrospective study investigated the feasibility and usefulness of SLN biopsy in dogs with surgical scars resulting from the removal of various solid tumors referred for further staging and/or adjuvant treatment options. Thirty-three dogs with 34 scars underwent SLN biopsy at a median of 50 days after primary tumor excision. An SLN was identified for 31/34 scars, translating to a detection rate of 91.2%. Metastases were identified with histopathology in 13/31 dogs (41.9%) and they all had an excision of a mast cell tumor. SLN biopsy should be suggested in dogs presenting with scars from prior solid tumor excision, considering the observed detection rate and the importance of knowing the metastatic status of the SLN in oncological diseases.Sentinel lymph node (SLN) biopsy is a well-established staging tool in canine oncology. This study aims to explore the feasibility of SLN biopsy in dogs with scars from prior excised solid malignancies that were referred for further tumor staging and/or adjuvant treatment options. Mapping was either performed using radiopharmaceutical, methylene blue, and/or near-infrared fluorescent (NIRF) imaging. Thirty-three dogs with 34 scars from prior excision of the mast cell tumor (MCT) (n = 29), soft tissue sarcoma (n = 2), oral melanoma (n = 1), subungual melanoma (n = 1), and mammary adenocarcinoma (n = 1) were retrospectively enrolled. Primary treatment consisted of curative intent/wide tumor excisions in 50.0% of dogs and marginal excision in the remaining 50.0%. The median time between tumor excision and SLN biopsy was 50 days (range 17–110 days). The procedure was successful in 31/34 scars, translating to a detection rate of 91.2%. The SLN did not correspond to the regional lymph node in 19/31 scars (61.3%). SLN metastases were histologically identified in 13/31 (41.9%) dogs, all of them affected by MCT. Based on our results, SLN biopsy using lymphoscintigraphy/methylene blue and/or NIRF is feasible in dogs presenting with scars from the prior surgical excision of solid tumors, and should be suggested for accurate nodal staging.

IN SITU ORAL MELANOMA: DIAGNOSIS, TREATMENT, AND FOLLOW-UP

Oral melanoma is an aggressive cancer in which the cells display melanocytic differentiation. In situ oral melanoma is considered an extremely rare tumor and the prognosis is poor compared to its cutaneous counterpart. A 67-year-old woman was referred for evaluation of a lesion on the maxillary alveolar mucosa. Intraoral examination revealed a nondetachable black patch on the maxillary alveolar mucosa extending to the hard palate with irregular borders and well-defined limits measuring 3 × 1.5 cm. A biopsy was performed, and microscopic analysis showed moderate atypical junctional melanocytic. Immunohistochemical analysis was positive for S-100, melan-A, and melanosome. The definitive diagnosis was in situ oral melanoma and the patient was treated surgically with partial maxillectomy. A definitive obturator prosthesis was made to provide effective rehabilitation. A 15-month follow-up showed no evidence of recurrence or metastasis. Oral melanoma is an aggressive cancer in which the cells display melanocytic differentiation. In situ oral melanoma is considered an extremely rare tumor and the prognosis is poor compared to its cutaneous counterpart. A 67-year-old woman was referred for evaluation of a lesion on the maxillary alveolar mucosa. Intraoral examination revealed a nondetachable black patch on the maxillary alveolar mucosa extending to the hard palate with irregular borders and well-defined limits measuring 3 × 1.5 cm. A biopsy was performed, and microscopic analysis showed moderate atypical junctional melanocytic. Immunohistochemical analysis was positive for S-100, melan-A, and melanosome. The definitive diagnosis was in situ oral melanoma and the patient was treated surgically with partial maxillectomy. A definitive obturator prosthesis was made to provide effective rehabilitation. A 15-month follow-up showed no evidence of recurrence or metastasis.

SOLITARY FOCAL GINGIVAL PIGMENTATION - A CASE REPORT

The report involves a 26-year-old dark-skinned female patient. The extraoral examination did not show alterations, and the intraoral examination revealed a spot of approximately 3 mm with an irregular shape and smooth surface on the attached gingiva above the upper right lateral incisor. A complementary approach included imaging and anatomopathologic examinations. The clinical diagnosis was melanocytic nevus. However, the differential diagnosis included melanotic macule, melanoacanthoma, and oral melanoma. We opted for excision of the lesion. The procedure consisted of an elliptical incision where the tissue was removed with a safety margin of approximately 2 mm. A normal keratinized stratified squamous epithelium and pigments of unknown origin in the connective tissue were observed in the histopathologic report. No nevus or malignant cells were found. Thus, the diagnosis was a tattoo of undetermined nature. Therefore, there are other forms of depositions of exogenous pigments in the gingival mucosa, in addition to amalgam tattoo.

Metabolic heterogeneity protects metastatic mucosal melanomas cells from ferroptosis.

Cancer heterogeneity has been proposed to be one of the main causes of metastatic dissemination and therapy failure. However, the underlying mechanisms of this phenomenon remain poorly understood. Melanoma is an aggressive malignancy with a high heterogeneity and metastatic potential. Therefore, the present study investigated the possible association between cancer heterogeneity and metastasis in melanoma. In total, two novel Chinese oral mucosal melanoma (COMM) cell lines, namely COMM-1 and COMM-2, were established for exploring methods into preventing the loss of cellular heterogeneity caused by long-term cell culture. Each cell line was grown under two different models of culture, which yielded two subtypes, one exhibited an adhesive morphology (COMM-AD), whereas the other was grown in suspension (COMM-SUS). Compared with the COMM-AD cells, the COMM-SUS cells exhibited higher metastatic capacities and autofluorescence. Further investigations indicated that the COMM-SUS cells exhibited metabolic reprogramming by taking up lactate produced by COMM-AD cells at increased levels to accumulate NADH through monocarboxylate transporter 1, whilst also increasing NADPH levels through the pentose phosphate pathway (PPP). Additionally, increased NADH and NADPH levels in the COMM-SUS cells, coupled with the upregulation of the anti-ferroptotic proteins, glutathione peroxidase 4 and ferroptosis suppressor protein 1, enabled them to resist ferroptotic cell death induced by oxidative stress during hematogenous dissemination. The inhibition of ferroptosis was found to substantially increase the metastatic capacity of COMM-AD cells. Furthermore, suppressing lactate uptake and impairing PPP activation significantly decreased the metastatic potential of the COMM-SUS cells. Thus, the present study on metabolic heterogeneity in COMM cells potentially provides a novel perspective for exploring this mechanism underlying cancer metastasis.

ORAL MUCOSAL MELANOMA: A CASE REPORT OF A LIFE-THREATENING DISEASE

Oral mucosal melanoma (OMM) is a rare malignancy of melanocytic origin, with a poor prognosis and low overall survival. We report a case of a 45-year-old male patient who presented with an ill-defined blackish-grey nodule, sometimes as a macule, affecting the maxillary gingiva and hard palate, with painless palpable lymph nodes. No clinical evidence of other extraoral lesions was found. Serologic tests for human immunodeficiency virus 1/2 were negative, and radiographs demonstrated a bone loss near the maxillary incisors. An incisional biopsy was performed in different sites, with OMM and Kaposi's sarcoma as clinical hypotheses. The histopathologic diagnosis was consistent with OMM and the patient was referred to the oncologist. OMM is a life-threatening disease, and its overall behavior is more aggressive than its cutaneous counterpart. All potential primary sites must be investigated in cases in which the oral cavity may not be the primary site.

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

BackgroundMicrosatellite 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.ObjectivesWe aimed to identify the frequency of dMMR/MSI by tumor type and evaluate the relationship between dMMR and MSI in tumors of dogs.AnimalsIn total, 101 dogs with 11 types of malignant tumors were included.MethodsWe 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.ResultsMicrosatellite 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 ImportanceMicrosatellite 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.

Pilot Study: Assessing the Expression of Serum Lactate Dehydrogenase and Peripheral Leukocyte Ratios in Canine Oral Malignant Melanoma.

Simple SummaryThis study aimed to assess the expression of novel blood biomarkers in dogs with oral malignant melanoma, an aggressive and common oral cancer in dogs. The results of this pilot study suggest that the concentrations of lactate dehydrogenase, which can be easily measured with blood samples, are significantly higher in dogs with oral malignant melanoma. These blood biomarkers have been shown to be of prognostic value in human melanoma patients, meaning that they can act to predict the potential behaviour of the tumour. Therefore, research into our canine patients should be viewed as being potentially very valuable, as the discovery of easily measurable prognostic biomarkers could significantly further not only our understanding of the underlying physiology of melanoma itself, but also change the way veterinary surgeons investigate and treat the disease in the future. This study lays the foundations for further, more extensive investigation, into the topic.Measurement of blood biomarkers such as lactate dehydrogenase (LDH) and peripheral leukocyte ratios have been shown to be of prognostic value in human melanoma patients. Previous veterinary studies have demonstrated that changes in these values are detectable in multiple canine cancer patients. However, to the authors’ knowledge, no studies have yet demonstrated an increase in LDH in canine oral malignant melanoma patients, nor has the effect of metastasis on LDH levels been explored. This retrospective pilot study included 18 dogs, of which 10 were healthy controls, 5 OMM patients with metastasis and 3 without metastasis. Serum LDH was measured and pre-treatment peripheral leucocyte ratios were calculated. LDH was measurable within all patient groups and a statistically significant difference in LDH levels was detected between patients with OMM and healthy controls (p < 0.05); however, no significant difference was detected between patients with or without metastatic disease. This study suggests that serum LDH levels are significantly increased in dogs with OMM compared to healthy controls, paving the way for further research to investigate the prognostic value of this biomarker.

Oral melanoma: a multicenter study of 69 patients from Japan.

The purpose of this multicenter retrospective study was to investigate the demographic characteristics and treatment outcomes of patients with mucosal malignant melanoma (MM) of the oral cavity. This was a multicenter study involving 8 Japanese universities. The medical records of 69 patients who were diagnosed with primary oral MM between January 2000 and December 2020 were retrospectively analyzed. Overall survival (OS) and prognostic factors for OS were analyzed statistically. There were 40 (58.0%) males and 29 (42.0%) females, and their mean (range) age was 69.8 ± 14.6 (22-96) years old. The most common primary site was the palate (30 patients, 43.5%). Stage IVA was the most common disease stage (36 patients, 52.2%). Radical therapy was performed in 55 patients (79.7%). The 2-year and 5-year OS rates of the 69 patients were 64.6% and 42.5%, respectively. The 2-year and 5-year OS rates of the stage III patients were 85.9% and 72.5%, respectively, and those of the stage IVA patients were 56.3% and 26.0%, respectively. The 1-year OS rate of the stage IVB/IVC patients was 26.7%. The 2-year and 5-year OS rates of the radical therapy group were 74.1% and 50.5%, respectively, whereas the 2-year OS rate of the non-radical therapy group was 26.0%. An advanced T classification was the only identified prognostic factor for OS (hazard ratio: 6.312, 95% confidence interval: 1.133-38.522, p < 0.05). Early detection and radical treatment are essential for improving the prognosis of oral MM patients. Early detection and adequate radical therapy leads to the better prognosis of oral MM patients.

Overview of common oral lesions.

This article summarises common oral lesions that clinicians may face in everyday practice by categorising them by clinical presentation: ulcerated lesions, white or mixed white-red lesions, lumps and bumps, and pigmented lesions. The pathologies covered include recurrent aphthous stomatitis, herpes simplex virus, oral squamous cell carcinoma, geographic tongue, oral candidosis, oral lichen planus, pre-malignant disorders, pyogenic granuloma, mucocele and squamous cell papilloma, oral melanoma, hairy tongue and amalgam tattoo. The objective of this review is to improve clinician knowledge and confidence in assessing and managing common oral lesions presenting in the primary care setting.

Tumor-Associated Macrophages in Canine Oral and Cutaneous Melanomas and Melanocytomas: Phenotypic and Prognostic Assessment.

The tumor microenvironment is a complex system, where neoplastic cells interact with immune and stromal cells. Tumor-associated macrophages (TAMs) are considered among the most numerically and biologically noteworthy cellular components in tumors and the attention on this cellular population has been growing during the last decade, both for its prognostic role and as a potential future therapeutic target. Melanoma, particularly the oral form, despite being one of the most immunogenic tumors, bears a poor prognosis in dogs and humans, due to its highly aggressive biological behavior and limited therapeutic options. The aims of this study are to characterize and quantify TAMs (using CD163, CD204, Iba1, and MAC387) in canine melanocytic tumors and to evaluate the association of these markers with diagnosis, histologic prognostic features, presence of metastases, and outcome, and to provide preliminary data for possible future therapies targeting TAMs. Seventy-two melanocytic tumors (27 oral melanomas, 25 cutaneous melanomas, 14 cutaneous melanocytomas, and 6 oral melanocytomas) were retrospectively selected and submitted to immunohistochemistry and double immunofluorescence. Double immunolabeling revealed that most CD163+ and CD204+cells co-expressed Iba1, which labeled also dendritic cells. Iba1 was instead rarely co-expressed with MAC387. Nevertheless, the expression of macrophagic markers showed a mild to moderate association among the four markers, except for CD204 and MAC387. The number of CD163+, CD204+, and MAC387+ cells was significantly higher in oral melanomas compared to oral melanocytomas (p < 0.001; p < 0.05 and p < 0.01, respectively), whereas Iba1 was differentially expressed in cutaneous melanomas and melanocytomas (p < 0.05). Moreover, CD163, IBA1 and MAC387 expression was associated with nuclear atypia and mitotic count. The number of CD163+cells was associated with the presence of metastases and tumor-related death in oral melanocytic tumors (p < 0.05 and p = 0.001, respectively).

Unraveling the Risk Factors and Etiology of the Canine Oral Mucosal Melanoma: Results of an Epidemiological Questionnaire, Oral Microbiome Analysis and Investigation of Papillomavirus Infection

Oral mucosal melanoma (OMM) is the most common oral cancer in dogs and is very aggressive in this species; its risk factors and etiology are yet to be determined. This study aimed to unravel the risk factors for the development of OMM in dogs and to investigate the possible presence of papillomaviruses as an etiological factor. A case-control study was conducted in 15 dogs with OMM and 15 paired controls whose owners answered an epidemiological questionnaire. Oral swabs from the same dogs were subjected to 16S rRNA sequencing for microbiome analyses. In addition, DNA fragments of OMM had their DNA extracted and amplified by polymerase chain reaction in an attempt to detect canine papillomaviruses. The gingiva was the most frequent anatomical site (47%) of OMM, and most tumors were stage III when diagnosed. Most dogs bearing OMM and the controls had grade 3 periodontal disease, and this factor, along with tartar treatment and tooth brushing, did not differ between cases and controls. Most dogs with OMM and most controls had contact with smokers; there was no statistically significant difference. Canine papillomaviruses were not detected among OMM cases. Tannerella forsythia and Porphyromonas gingivalis were significantly increased in case dogs compared to the controls. As these bacteria are reportedly involved in the pathogenesis of periodontal disease and esophageal cancer in humans, we suggest that they might be risk factors for the development of canine OMM. The limitations of this study include the low number of dogs, and therefore, further studies on canine OMM with larger numbers of animals are encouraged.

Melanoma In Situ of the Hard Palate.

Mucosal melanoma of the oral cavity is rare and highly aggressive, thought to represent less than 1% of melanomas. Within this subgroup, melanoma in situ has been rarely described. We describe the case of a 54-year-old male with history of tobacco use presented with extensive pigmented changes to the hard and soft palate. Biopsy demonstrated melanoma in situ. Mucosal surgical resection was performed with all peripheral epithelial margins involved and negative deep margins. After extensive multidisciplinary discussion, remaining mucosal margins were re-resected to the teeth and posteriorly onto the soft palate. Deep margins remained negative with melanoma in situ still present peripherally. The patient is routinely surveilled without evidence of recurrence. Oral cavity melanoma in situ has been rarely described. The treatment of choice is surgical excision, ranging from wide local excision to composite resections, with consideration given to medical adjuncts. This unique entity should be considered in pigmented oral abnormalities.

Multi-institutional retrospective study of canine foot pad malignant melanomas: 20 cases.

Melanomas arising from the foot pad are a rare clinical entity in dogs. The biologic behaviour of foot pad malignant melanoma is not well understood, and these tumours are infrequently described. The objective of this study was to evaluate the clinical characteristics of primary canine foot pad melanoma in a larger cohort of patients. Eligible cases were solicited from the American College of Veterinary Internal Medicine (ACVIM) Oncology listserv for retrospective review. Included dogs had a cytologic and/or histologic diagnosis of foot pad melanoma evaluated by a board-certified clinical or anatomic pathologist. Dogs with cutaneous, oral, digital, subungual or interdigital melanomas were excluded. A total of 20 cases were included. Eleven dogs received various adjuvant therapies including chemotherapy, radiation therapy, and/or the ONCEPT canine melanoma vaccine following surgery. At diagnosis, regional lymph node metastasis was observed in four dogs (20%). Seven dogs developed subsequent regional and/or distant metastasis for an overall metastatic rate of 55%. The progression-free interval (PFI) was 101 days (range, 20-960 days). The median survival time (MST) was 240 days (range, 25-479 days). For dogs receiving adjuvant therapy, the MST was 159 days (range, 25-387 days). Canine foot pad melanoma is a rare neoplasm that can exhibit an aggressive behaviour.

Association of Systemic Inflammatory and Immune Indices With Survival in Canine Patients With Oral Melanoma, Treated With Experimental Immunotherapy Alone or Experimental Immunotherapy Plus Metronomic Chemotherapy.

Analysis of the expression of inflammatory markers before starting treatment in human patients with cancer helps to predict outcomes and prognosis; however, there have been few studies on this topic in veterinary medicine. The present study aimed to evaluate inflammatory indices before treatment with autologous antitumor vaccine alone or this vaccine plus metronomic chemotherapy (MC) to predict response and prognosis. The indices included the neutrophil–lymphocyte ratio (NRL), platelet–lymphocyte ratio (PLR), monocyte–lymphocyte ratio (MLR), systemic immune-inflammation index (SII), C-reactive-protein–albumin ratio (CRP/ALB), lactate dehydrogenase level (LDH), frequency of blood lymphocyte subsets (CD4+, CD8+, Treg, and CD4/CD8 ratio) and frequency of blood myeloid-derived suppressor cells (MDSCs: monocytic [M]- MDSCs, and granulocytic [PMN]-MDSCs). Blood samples were collected from 25 dogs with oral melanoma treated with the autologous antitumor vaccine and from nine dogs that received MC plus vaccine before surgery. There were no statistically significant differences in the progression-free survival (PFS) or overall survival (OS) between the groups. In addition to the clinical stage, the CRP/ALB ratio and blood circulating Tregs in the univariate analysis showed an association with PFS and OS, and thus were selected for multivariable analysis. The CRP/ALB ratio was associated with PFS [hazard ratio (HR), 1.1; 95% confidence interval (CI), 1.0–1.1; p = 0.017] and OS [HR, 1; 95%CI, 1.0–1.1; p = 0.023]. Similarly, Treg was associated with PFS (HR, 1.6; 95% CI, 1.2–2.1; p = 0.001) and OS (HR, 1.6; 95% CI, 1.2–2.1; p = 0.001). Furthermore, canine patients with a CRP/ALB ratio above the cut-off point of 1.9 (established by receiver operating characteristic curve analysis) had worse PFS and OS, indicating the impact of the preoperative CRP/ALB ratio on the PFS and OS of dogs with oral melanoma. The CRP/ALB ratio and frequency of circulating Tregs are potential prognostic markers in dogs with oral melanoma.

P06: Oral mucosal melanoma: not the same as the cutaneous variant

P06: Oral mucosal melanoma: not the same as the cutaneous variant

Abstract 4171: Treatment of canine soft tissue sarcomas and melanomas with intratumoral collagen-anchored IL-2 and IL-12 is safe and effective

Abstract Introduction: Successful translation of novel cancer immunotherapies could be accelerated by using tumor models that recapitulate human disease and receive relevant standard-of-care treatments. Some cancers that naturally arise in pet dogs share critical features with human disease including tumor heterogeneity (immune infiltration, mutational burden, metastatic progression) and patient characteristics (outbred population, immunocompetence, age, microbiome). Investigating novel immunotherapies alongside radiation, chemotherapy, or surgical treatment of spontaneous canine cancers meaningfully informs their clinical translation. Methods: We have developed interleukin -2 and -12 cytokine fusion proteins that bind and anchor to collagen after intratumoral administration and have shown their superior activity and tolerability in murine tumor models (Momin 2019). Here in pet dogs, we test these cytokines for safety and efficacy in two cancer types. Soft tissue sarcomas (n=10) were treated with intratumoral IL-2 and -12 using different dose schedules prior to surgical resection with subsequent tumor tissues assessed by histology for immune infiltrates and by Nanostring for whole tumor transcriptomics. Oral malignant melanomas (n=10) were treated with 9 Gy radiation at day 0, and on day 1 treated with intratumoral injection of the cytokines Q2W for 6 total doses, with dose escalation performed in cohorts of 3. Plasma was collected for PK/PD analysis of drug and IFN-g post-injection, with serial CBC/chemistry profiles and CT scans for assessment of safety and radiologic response, respectively. Results: Intratumoral dosing of collagen binding cytokines was well tolerated by 19/20 dogs, with transient body temperature elevation observed 24-72 hours post-injection and 1 episode of grade 3 transaminase elevation. Magnitude of fever did not correlate with peak serum IFN-g or cytokine dose level. At the lowest dose level (17 ug/kg IL-2, 40 ug/m2 IL-12), 1/3 pet dogs with oral melanomas achieved CR by RECIST criteria, and 3/3 pet dogs achieved near CR at the 2x dose level. Transcriptomic analysis of treated sarcomas revealed enrichment for antigen processing and T cell function two days after treatment. Moreover, IDO1 was upregulated in treated tumors, which suggests its systemic inhibitors combined with the locally-delivered cytokines may potentiate stronger responses. Conclusions: This data supports the safety and efficacy of intratumorally delivered IL-2 and IL-12 collagen binding cytokines and the ability to combine with standard-of-care resection or radiation therapy. We are continuing to enroll dogs to evaluate safety and efficacy at higher dose levels, including response at metastatic sites. Canine cancers bridge the gap between murine and human disease, accelerating the build-test-learn design cycle for novel immunotherapies and treatment combinations. Citation Format: Jordan Stinson, Allison Sheen, Jordan Hampel, Noor Momin, Rebecca Bernstein, Rebecca Kamerer, Timothy M. Fan, K. Dane Wittrup. Treatment of canine soft tissue sarcomas and melanomas with intratumoral collagen-anchored IL-2 and IL-12 is safe and effective [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4171.