Carlos A. Torres-Cabala

Loss of PTEN promotes resistance to T cell–mediated immunotherapy

UNLABELLED T cell-mediated immunotherapies are promising cancer treatments. However, most patients still fail to respond to these therapies. The molecular determinants of immune resistance are poorly understood. We show that loss of PTEN in tumor cells in preclinical models of melanoma inhibits T cell-mediated tumor killing and decreases T-cell trafficking into tumors. In patients, PTEN loss correlates with decreased T-cell infiltration at tumor sites, reduced likelihood of successful T-cell expansion from resected tumors, and inferior outcomes with PD-1 inhibitor therapy. PTEN loss in tumor cells increased the expression of immunosuppressive cytokines, resulting in decreased T-cell infiltration in tumors, and inhibited autophagy, which decreased T cell-mediated cell death. Treatment with a selective PI3Kβ inhibitor improved the efficacy of both anti-PD-1 and anti-CTLA-4 antibodies in murine models. Together, these findings demonstrate that PTEN loss promotes immune resistance and support the rationale to explore combinations of immunotherapies and PI3K-AKT pathway inhibitors. SIGNIFICANCE This study adds to the growing evidence that oncogenic pathways in tumors can promote resistance to the antitumor immune response. As PTEN loss and PI3K-AKT pathway activation occur in multiple tumor types, the results support the rationale to further evaluate combinatorial strategies targeting the PI3K-AKT pathway to increase the efficacy of immunotherapy.

Correlation between KIT expression and KIT mutation in melanoma: a study of 173 cases with emphasis on the acral-lentiginous/mucosal type

The role of immunohistochemistry in the assessment of KIT status in melanomas, especially acral lentiginous/mucosal, is not well established. Although the reported prevalence of KIT mutations in acral lentiginous/mucosal melanomas is relatively low, detection of mutations in KIT can have profound therapeutic implications. We evaluated the efficacy of immunohistochemistry to predict mutations in KIT. One hundred seventy-three tumors, comprising primary and metastatic melanomas (141 acral lentiginous/mucosal, 5 nodular, 4 lentigo maligna, 3 superficial spreading, 2 uveal, 1 melanoma of soft parts, 8 metastases from unclassified primaries, and 9 metastases from unknown primaries) were studied. Immunohistochemical expression of KIT using an anti-CD117 antibody and KIT mutational analysis by gene sequencing of exons 11, 13, and 17 were performed. Eighty-one percent of acral lentiginous/mucosal melanomas, primary and metastatic, showed KIT expression by at least 5% of the tumor cells. The overall frequency of activating KIT gene mutations in acral lentiginous/mucosal melanomas was 15% (14 out of 91 cases), being the L576P mutation in exon 11 the most frequently detected (4 of 14 cases). Cases showing less than 10% positive tumor cells were negative for KIT mutations. Eighty-two percent (12 of 14) of cases positive for KIT mutation showed KIT expression in more than 50% of the cells. An association between immunohistochemical expression of KIT and mutation status was found (P=0.007). Immunohistochemical expression of KIT in less than 10% of the cells of the invasive component of acral lentiginous/mucosal melanomas appears to be a strong negative predictor of KIT mutation and therefore can potentially be used to triage cases for additional KIT genotyping.

HER-2/neu expression in extramammary Paget disease: a clinicopathologic and immunohistochemistry study of 47 cases with and without underlying malignancy.

Extramammary Paget disease (EMPD) is an infrequent skin cancer sometimes representing a secondary event caused by extension of an underlying carcinoma. Her‐2/neu overexpression in breast cancer is correlated with a more aggressive behavior, but anti‐Her‐2/neu therapy improves survival in these patients. We investigated Her‐2/neu expression by immunohistochemistry in cases of EMPD with and without underlying malignancy to try to correlate with tumor recurrence, progression and possible targeted therapy. Forty‐seven cases were analyzed (6 from the scrotum, 7 perianal region, 1 axilla and 33 vulva). Two cases had invasive EMPD (one from vulva and one from scrotum). The overall Her‐2/neu expression was 31.9%. Of the noninvasive EMPD of the vulva (32 cases), Her‐2/neu was shown in 38%. The case of invasive vulvar EMPD was negative. All six scrotal EMPD lacked Her2/neu expression. Her‐2/neu was expressed in two of seven perianal cases (33.3%). The EMPD on the axilla (one case) was negative. Eighteen cases had recurrence, and of these, 44.4% expressed Her‐2/neu in the initial lesion. A high proportion of EMPD showed Her‐2/neu expression (31.9%), indicating that these patients may benefit from targeted therapy. The proportion of positive cases was higher in lesions that had recurred at last follow up (44.4%), suggesting a more aggressive behavior.

Cutaneous metastases of malignant melanoma: a clinicopathologic study of 192 cases with emphasis on the morphologic spectrum.

Metastatic melanoma represents one of the most common types of cutaneous metastases. In up to 5% of patients, metastatic melanoma can be the first manifestation of the disease. For the most part, the histologic diagnosis of metastatic melanoma poses little diagnostic difficulty; however, some metastases may adopt unusual or unfamiliar appearances mimicking other benign and malignant conditions. We present a study of 192 cases of cutaneous metastatic melanomas with special emphasis on their spectrum of morphologic features. The patients were 115 men and 77 women, 23-91 years of age (mean 57 years). Most tumors were located on the proximal legs, scalp, and arms and ranged from 0.8 to 3.0 cm. One hundred ten cases showed the classic morphologic appearance of melanoma (well-circumscribed epithelioid dermal/subcutaneous nodule), 82 cases showed unusual histologic appearances that mimicked other benign and malignant neoplasms. In 16 patients (8.3%), there was no evidence of primary melanoma and the cutaneous metastasis was the only manifestation of the disease. The histologic diagnosis of cutaneous metastatic melanoma can pose difficulties for diagnosis, especially in the face of an unknown primary neoplasm. Unusual features observed in this series included examples of cutaneous metastatic melanoma that closely simulated metastatic carcinoma, dermatofibroma, leiomyosarcoma, angiosarcoma, nevoid melanoma, halo nevus, blue nevi, and atypical fibroxanthoma. Several cases also showed rhabdoid, balloon cell, and alveolar features. Immunohistochemical stains plus careful clinical history helped to establish the correct diagnosis. Our series illustrates that the differential diagnosis of cutaneous metastatic melanoma can be broad and difficult. To the best of our knowledge, this is the largest series of cutaneous metastatic melanomas reported in the literature.

Immunohistochemical expression of S100A6 in cellular neurothekeoma: Clinicopathologic and immunohistochemical analysis of 31 cases

Neurothekeoma is a term introduced by Gallager and Helwig describing a superficial tumor of purported nerve sheath derivation, with cellular and myxoid types. Recently, it has been suggested that the cellular type does not have nerve sheath differentiation. This subtype represents an uncommon neoplasm and sometimes can be problematic to diagnose because it can be easily mistaken for melanoma. We studied the immunohistochemical features of 31 cases of cellular neurothekeomas to evaluate their immunoprofile. Immunohistochemical studies were performed in all 31 cases with formalin-fixed paraffin-embedded tissue sections with antibodies against S100 protein, S100A6, and melanoma antigen recognized by T-cells (MART-1). In addition, 8 cases were evaluated for HMB-45 antigen, keratin (with a pankeratin cocktail), epithelial membrane (EMA), and smooth muscle antigen (SMA). The lesions were from 8 men and 23 women aged 6-64 years (mean 35 years). Four tumors were located on the nose; 4 scalp; 4 finger; 3 thigh; 2 shoulder; 2 wrist; 2 hand; and 1 each on pelvis, cheek, toe, chest, eyebrow, forearm, penis, axilla, mouth, and leg. All tumors were positive for S100A6 (100%) and negative for cytokeratin, HMB-45 antigen, MART-1, and EMA (100%); 29 cases were negative for S100 protein (93.5%; the 2 positive cases had only scattered cells labeled), and only 2 cases were focally positive for SMA (7.5%). Therefore, the combination of strong immunoreactivity for S100A6, in nested dermal spindle cell proliferations, and lack of S100 protein or keratin, supports a diagnosis of cellular neurothekeoma.

Dermatologic toxicities to targeted cancer therapy: shared clinical and histologic adverse skin reactions

Dermatologic toxicities (DT) to targeted cancer therapy may present as inflammatory dermatoses, keratoses, and as benign and malignant squamous proliferations.

Molecular Platforms Utilized to Detect BRAF V600E Mutation in Melanoma

Metastatic melanoma (MM) is a deadly skin disease refractory to standard chemotherapy. Despite numerous clinical and pathological parameters derived to guide patient management, clinical outcomes in melanoma patients remain difficult to predict. There is a critical need to delineate the important biomarkers typical of this disease. These biomarkers will ideally illuminate those key biochemical pathways responsible for the aggressive behavior of melanoma and, in the process, unveil new opportunities for the design of rational therapeutic interventions in high-risk patients. The most common recurring mutation in cutaneous melanoma is the prooncogenic BRAF V600E mutation that drives melanoma cell proliferation. The development of RAF inhibitors targeted against BRAF V600E mutant melanoma cells has revolutionized the treatment of MM. Clinical trials with BRAF inhibitor vemurafenib have shown objective clinical response and improved survival in patients with MM; therefore, knowledge of the molecular signature of melanoma in patients will be important in directing management decisions. Several molecular platforms exist to analyze the mutation status of melanoma. These include Sanger sequencing, pyrosequencing, allele-specific reverse transcriptase polymerase chain reaction, mass spectrometry base sequencing (Sequenom), high-resolution melting curve analysis, and next-generation sequencing methods using microfluidics technology. The Food and Drug Administration has approved the cobas BRAF V600 Mutation Test developed by Roche to analyze BRAF mutation status in formalin-fixed paraffin-embedded tumor samples. The cobas Mutation Test has been designed specifically to detect BRAF V600E mutations, and the analytic performance of this assay has demonstrated >99% sensitivity in the detection of BRAF V600E mutation when compared with the Sanger sequencing method and confirmed with the next-generation sequencing 454-pyrosequencing technology. The lower limit of detection of the percentage of mutant alleles in a tissue sample for the cobas test is less than 4%-5%. Some cross-reactivity with other variants of mutant BRAF was seen with the cobas V600 platform; however, this clinical test offers highly sensitive reproducible BRAF V600E mutation analysis in formalin-fixed paraffin-embedded tumor samples.

Diverse types of dermatologic toxicities from immune checkpoint blockade therapy

Immunomodulatory drugs that leverages host immune mechanisms to destroy tumor cells have been met with great promise in the treatment of cancer. Immunotherapy, targeting cytotoxic T‐lymphocyte‐associated antigen 4 (CTLA‐4) and the programmed cell death 1 (PD‐1) receptor and its ligand (PD‐L1) have shown tremendous improvements in the survival of patients with advanced solid tumors. However, the development of dermatologic toxicity (DT) is a consequence to immunotherapy. Review of published reports of the DT to immunotherapy revealed patients receiving anti‐CTCLA‐4 antibody or anti‐PD‐1/PD‐L1 antibody often develop a DT of any type and grade. In this article, of the 3825 patients who were treated with anti‐PD‐1 and of 556 patients receiving anti‐PD‐L1, DT of any type and grade were reported in 1474 (∼39%) and 95 (∼17%) of patients, respectively. The emergence of specific types of DT to immunotherapy is beginning to be recognized can be categorized into four groups: (a) inflammatory, (b) immunobullous, (c) alteration of keratinocytes and (d) alteration of melanocytes. Lichenoid dermatitis and bullous pemphigoid appear to be DT more associated with anti‐PD‐1/PD‐L1 antibody. The DT profile in patients receiving immunotherapy is diverse, and early recognition of specific types of DT that clinicians may encounter is critical for optimal patient care

Diagnostic utility and comparative immunohistochemical analysis of MITF-1 and SOX10 to distinguish melanoma in situ and actinic keratosis: a clinicopathological and immunohistochemical study of 70 cases.

Abstract:The histologic assessment of intraepidermal melanocytic proliferations involving sun-damaged skin may be challenging in scant biopsy material. Melanoma in situ may occasionally be confused with intraepidermal melanocytic hyperplasia on sun-damaged skin; thus, dermatopathologists may use immunohistochemical studies to help distinguish these entities. Historically, melanoma antigen recognized by T-cells 1 (MART-1) has been regarded as a valuable stain to confirm intraepidermal melanocytes; however, MART-1 may overestimate the number of melanocytes because it labels the melanoma dendrites and might also label pigmented keratinocytes, including structures mimicking junctional melanocytic nests in the setting of a lichenoid infiltrate. A total of 70 cases were retrospectively chosen, including 50 cases of melanoma in situ and 20 cases of actinic keratoses. SOX10 and microphthalmia transcription factor 1 (MITF-1) were performed in all cases. In all cases, the number of cells within epidermis that were identified as melanocytes by immunohistochemistry was compared with the number of melanocytes observed by morphology on hematoxylin and eosin sections. All cases of melanoma in situ showed expression of SOX10; however, the proportion of atypical melanocytes showing strong nuclear positivity was variable and did not approach that seen in MITF-1. There was no expression of either MITF-1 or SOX10 in adjacent pigmented keratinocytes in the cases of actinic keratoses. Both MITF-1 and SOX10 can be used to differentiate melanoma in situ from actinic keratosis with melanocytic hyperplasia; however, MITF-1 exhibits slight superior sensitivity and seems to be a more effective immunostain than SOX10 for the identification and quantification of melanocytes in the setting of melanoma in situ, especially in cases where there is limited tissue.

Density, Distribution, and Composition of Immune Infiltrates Correlate with Survival in Merkel Cell Carcinoma.

Purpose: Merkel cell carcinoma (MCC) is an aggressive cancer with frequent metastasis and death with few effective therapies. Because programmed death ligand-1 (PD-L1) is frequently expressed in MCC, immune checkpoint blockade has been leveraged as treatment for metastatic disease. There is therefore a critical need to understand the relationships between MCPyV status, immune profiles, and patient outcomes. Experimental Design: IHC for CD3, CD8, PD-1, PD-L1, and MCPyV T-antigen (to determine MCPyV status) was performed on 62 primary MCCs with annotated clinical outcomes. Automated image analysis quantified immune cell density (positive cells/mm2) at discrete geographic locations (tumor periphery, center, and hotspot). T-cell receptor sequencing (TCRseq) was performed in a subset of MCCs. Results: No histopathologic variable associated with overall survival (OS) or disease-specific survival (DSS), whereas higher CD3+ (P = 0.004) and CD8+ (P = 0.037) T-cell density at the tumor periphery associated with improved OS. Higher CD8+ T-cell density at the tumor periphery associated with improved DSS (P = 0.049). Stratifying MCCs according to MCPyV status, higher CD3+ (P = 0.026) and CD8+ (P = 0.015) T-cell density at the tumor periphery associated with improved OS for MCPyV+ but not MCPyV− MCC. TCRseq revealed clonal overlap among MCPyV+ samples, suggesting an antigen-specific response against a unifying antigen. Conclusions: These findings establish the tumor-associated immune infiltrate at the tumor periphery as a robust prognostic indicator in MCC and provide a mechanistic rationale to further examine whether the immune infiltrate at the tumor periphery is relevant as a biomarker for response in ongoing and future checkpoint inhibitor trials in MCC. Clin Cancer Res; 22(22); 5553–63. ©2016 AACR.