High GILT Expression Is Associated with Improved Survival in Metastatic Melanoma Patients Treated with Immune Checkpoint Inhibition.

Gamma-interferon-inducible lysosomal thiol reductase (GILT) is critical for MHC class II restricted presentation of multiple melanoma antigens. There is variable GILT protein expression in malignant melanocytes in melanoma specimens. High GILT mRNA expression in melanoma specimens is associated with improved overall survival, before the advent of immune checkpoint inhibitors (ICI). However, the association of GILT in metastatic melanoma with survival in patients treated with ICI and the cell type expressing GILT associated with survival have not been determined. Using RNA sequencing datasets, high GILT mRNA expression in metastatic melanoma specimens was associated with improved progression-free and overall survival in patients treated with ICI. A clinical dataset of metastatic melanoma specimens was generated and annotated with clinical information. Positive GILT immunohistochemical staining in antigen presenting cells and melanoma cells was observed in 100% and 65% of metastatic melanoma specimens, respectively. In the subset of patients treated with ICI in the clinical dataset, high GILT protein expression within melanoma cells was associated with improved overall survival. The association of GILT mRNA and protein expression with survival was independent of cancer stage. These studies support that high GILT mRNA expression in bulk tumor samples and high GILT protein expression in melanoma cells is associated with improved survival in ICI-treated patients. These findings support further investigation of GILT as a biomarker to predict the response to ICI.

KRAS mutation correlates with accelerated metastatic progression in patients with colorectal liver metastases.

BACKGROUND: Observational studies of patients with primary colorectal cancer have identified KRAS mutation as a marker of poor prognosis. To examine more directly whether KRAS mutations are associated with accelerated metastatic progression, we evaluated KRAS mutation as well as Ki-67 expression in patients with colorectal liver metastases not treated with cetuximab. METHODS: KRAS mutation status was assessed in a series of resected or sampled colorectal liver metastases. In a subset of these tumors, Ki-67 antigen expression was assessed by immunohistochemical stains. Median follow-up after liver resection or biopsy was 2.3 years. RESULTS: KRAS mutation in the liver metastasis was detected in 27% of the 188 patients. High Ki-67 expression in the liver metastasis was identified in 62% of 124 patients analyzed. Both markers were associated with multiple liver metastases and shorter time interval to their detection. KRAS mutation and high Ki-67 expression were independent predictors of poor survival after colon resection (hazard ratio [HR] 1.9 [95% confidence interval (95% CI), 1.1-3.4], HR 2.6 [95% CI, 1.4-4.8], respectively). Tumors with high Ki-67 expression were less likely to be selected for liver resection, and KRAS mutation was independently associated with poor survival after liver resection (HR 2.4 [95% CI, 1.4-4.0]). CONCLUSIONS: KRAS mutation is associated with more rapid and aggressive metastatic behavior of colorectal liver metastases. These data suggest an important role for KRAS activation in colorectal cancer progression and support continued efforts to develop KRAS pathway inhibitors for this disease.

Improved testing for microsatellite instability in colorectal cancer using a simplified 3-marker assay.

BACKGROUND: In colorectal cancer (CRC), microsatellite instability (MSI) is a valuable marker of defective DNA mismatch repair that identifies cancers with distinct phenotypic properties, including favorable survival. However, the optimal assay for MSI status is unknown. We have evaluated a simplified 3-marker assay for MSI and compared it with the 5-marker (NCI) assay to see if technical variations in MSI testing are important. MATERIALS AND METHODS: DNA samples from 357 CRCs were evaluated for MSI using the 5 microsatellite markers recommended for the NCI assay (BAT 25, BAT26, D2S123, D5S346, and D17S250). Results were compared with a simplified 3-marker assay (BAT25, BAT26, and D2S123). CRCs identified as MSI were evaluated for their clinical, pathological, and genetic characteristics. RESULTS: The 5-marker assay identified 96 cancers as MSI. Only 56 of these were MSI by the 3-marker assay (3-marker+ group), leaving 40 cases identified as MSI only by NCI criteria (3-marker- group). The remaining 261 cancers were microsatellite stable (MSS). The 3-marker+ MSI tumors had features characteristic of MSI tumors: more proximal, poorly differentiated, associated with hereditary nonpolyposis colorectal cancer (HNPCC), more BRAF mutations, fewer KRAS mutations, better 5-year disease-specific survival, more frequent mismatch repair (MMR) protein loss, and less likely to be metastatic on presentation (P < .05). Chromosomal arm loss was observed only in 3-marker- MSI and MSS cancers (P < .05). CONCLUSION: The 3-marker MSI assay outperforms the traditional 5-marker assay for identifying patients with favorable prognosis and homogeneous clinical and genetic features. More accurate MSI testing should improve prognostic and predictive scoring systems for colorectal cancer.

KRAS mutation and microsatellite instability: two genetic markers of early tumor development that influence the prognosis of colorectal cancer.

INTRODUCTION: We examined two genetic markers established early in colorectal tumor development, microsatellite instability (MSI) and mutation of the KRAS proto-oncogene, to see if these genetic changes influence metastatic disease progression and survival. PATIENTS AND METHODS: MSI and KRAS mutation status were assessed in 532 primary adenocarcinomas (stage I-IV) from patients treated by colon resection. Median follow-up was 4.1 years (range 0-13.3 years) overall, 5.4 years for survivors. RESULTS: MSI and KRAS mutation were detected in 12 and 36% of cases, respectively. MSI was more common in early-stage disease (I, 15%; II, 21%; III, 10%; IV, 2%; P = 0.0001). Prevalence of KRAS mutation did not vary with stage (I, 36%; II, 34%; III, 35%; IV, 40%; P = ns). Disease-specific survival was far superior for MSI tumors than for microsatellite stability (MSS) tumors (5-year survival 92 vs. 59%, P < 0.0001). KRAS mutation was a marker of poor survival (5-year survival 55 vs. 68%, P = 0.0002). Using Cox regression analysis MSI, KRAS mutation, and stage were strong independent predictors of survival in the entire patient population. A high-mortality group with MSS/KRAS-mutant tumors was identified within the stage I and II cohort. CONCLUSIONS: MSI and KRAS mutation provide fundamental genetic signatures influencing tumor behavior across patient subsets and stages of tumor development.

Routine biopsy of Cloquet's node is of limited value in sentinel node positive melanoma patients.

BACKGROUND AND OBJECTIVES: Biopsy of Cloquet's node (CN) during groin dissection has been used to indicate need for pelvic dissection. With earlier detection of microscopic regional disease in the era of sentinel node biopsy (SNB), frequency of positive CN may be so low that routine biopsy is unwarranted. METHODS: Patients with positive groin SNB from 2000 to 2008 were identified from two centers. Cases where CN was identified at completion node dissection were selected. Lymphoscintigraphic, surgical, pathologic, and recurrence data were reviewed. RESULTS: CN was identified in 53 cases. Median age was 44.5 years (range 7-77); median Breslow depth, 1.98 mm (range 0.5-25.0); % Clark's level IV/V, 90%; and % ulceration, 41.5%. Fifty (94.3%) underwent groin dissection alone; three others underwent concomitant pelvic dissection. Two (3.8%) patients had positive CN; both had additional indications for pelvic dissection. Delayed pelvic recurrence rate was 2/53 (3.8%); both patients had negative CN. In the three patients treated with concurrent groin and pelvic dissection, CN reflected pelvic nodal status in two cases; the third had pelvic metastases despite negative CN. CONCLUSIONS: After positive SNB, disease involvement of CN is rare. Patients with positive biopsies of CN in the SNB era appear likely to have additional indications for pelvic dissection, minimizing utility of CN biopsy. Routine intraoperative sampling of CN may not be warranted during groin dissection for positive SNB.

c-Met gene amplification is associated with advanced stage colorectal cancer and liver metastases.

The c-Met proto-oncogene encodes a receptor tyrosine kinase (TK) that promotes invasive tumor growth and metastasis. Recent studies show that the presence of c-Met gene amplification is predictive for selective c-Met TK inhibitors in gastric cancer and lung cancer. In this study, we utilized a highly quantitative PCR/ligase detection reaction technique to quantify c-Met gene copy number in primary colorectal cancer (CRC) (N=247), liver metastases (N=147), and paired normal tissues. We identified no differences in c-Met gene copy number between normal colonic mucosa and liver tissue. However, mean c-Met gene copy number was significantly elevated in CRC compared with normal mucosa (P<0.001), and in liver metastases compared with normal liver (P<0.001). Furthermore, a significant increase in c-Met was seen in liver metastases compared with primary CRC (P<0.0001). c-Met gene amplification was observed in 2% (3/177) of localized cancers, 9% (6/70) of cancers with distant metastases (P<0.02), and 18% (25/147) of liver metastases (P<0.01). Among patients treated by liver resection, there was a trend toward poorer 3-year survival in association with c-Met gene amplification (P=0.07). Slight increases in c-Met copy number can be detected in localized CRCs, but gene amplification is largely restricted to Stage IV primary cancers and liver metastases. c-Met gene amplification is linked to metastatic progression, and is a viable target for a significant subset of advanced CRC.

Thrombotic Thrombocytopenic Purpura due to Checkpoint Inhibitors.

Ipilimumab is a monoclonal antibody that enhances the efficacy of the immune system by targeting a cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), which is a protein receptor that downregulates the immune system. Nivolumab is also a humanized monoclonal antibody that targets another protein receptor that prevents activated T cells from attacking the cancer; this receptor is called programmed cell death 1 (PD-1). The FDA approved ipilimumab combined with nivolumab as a frontline therapy for patients with metastatic melanoma or renal cell carcinoma and as a second-line therapy for patients with microsatellite instability-high (MSI-H) metastatic colon cancer. Immune-related adverse events such as autoimmune colitis, pneumonitis, hepatitis, nephritis, hypophysitis, and thyroiditis may occur during or weeks to months after therapy. We report a case of thrombotic thrombocytopenic purpura (TTP) in a patient with metastatic renal cell carcinoma following one cycle of ipilimumab and nivolumab. Only one case report of ipilimumab-induced TTP exists in the medical literature. With the wide use of immunotherapy to treat cancers, physicians need to be aware of this rare immune-related adverse event.

Mechanisms of resistance to BRAF and MEK inhibitors and clinical update of US Food and Drug Administration-approved targeted therapy in advanced melanoma.

Approximately 50% of melanomas harbor an activating BRAF mutation. Combined BRAF and MEK inhibitors such as dabrafenib and trametinib, vemurafenib and cobimetinib, and encorafenib and binimetinib are US Food and Drug Administration (FDA)-approved to treat patients with BRAF V600-mutated advanced melanoma. Both genetic and epigenetic alterations play a major role in resistance to BRAF inhibitors by reactivation of the MAPK and/or the PI3K-Akt pathways. The role of BRAF inhibitors in modulating the immunomicroenvironment and perhaps enhancing the efficacy of checkpoint inhibitors is gaining interest. This article provides a comprehensive review of mechanisms of resistance to BRAF and MEK inhibitors in melanoma and summarizes landmark trials that led to the FDA approval of BRAF and MEK inhibitors in metastatic melanoma.

Colorectal cancer in the very young: a comparative study of tumor markers, pathology and survival in early onset and adult onset patients.

INTRODUCTION: Colorectal cancer (CRC) diagnosed before age 30 years is a fatal disease whose biology remains poorly understood. To understand its pathogenesis, we compared molecular and clinical data in surgically treated early-age onset and adult onset patients. MATERIALS AND METHODS: Clinical data and tumor tissue were collected retrospectively for 94 patients with early-age onset CRC (age ≤30 years) and compared to 275 adult CRC patients (age ≥50 years). Tumor morphology, microsatellite instability (MSI) and stability (MSS), KRAS and BRAF mutations, and mismatch repair (MMR) expression (MSH2, MLH1, MSH6, PMS2) were assessed. RESULTS: Early-age CRC was distinguished from adult CRC by advanced stage presentation (P<0.001), frequent high grade cancers (P<0.001), and poor prognosis (P<0.001). MSI was associated with favorable survival and MMR loss in both groups. Compared to adults, MSI in early-onset CRC was more prevalent (P<0.01), not tightly linked to MLH1/PMS2 loss, and never associated with BRAFV600E mutations (P<0.01). MSS/BRAFV600E genotype had poor prognosis and was more prevalent in early-age CRC (9% vs. 3%). DISCUSSION: Specific genetic subtypes are found at different frequencies in early-age onset and adult onset CRC. Complete absence of the indolent MSI/BRAFV600E genotype and enrichment in the unfavorable MSS/BRAFV600E genotype help explain the poor prognosis of early onset CRC.

A current perspective on local excision of rectal cancer.

Local excision of rectal cancer is appealing because of its technical ease and excellent functional results, but concern over inadequate pathologic staging and inferior treatment outcomes when compared with radical surgery remain a major hurdle for its widespread use. Local failure rates in modern series for local excision are 4%-18% for T1 rectal cancers and 22%-67% for T2 cancers, and cancer cure rates are only 70%-80%. In addition, data from the past decade suggest that preoperative staging with endorectal ultrasound, use of postoperative adjuvant chemotherapy/radiation therapy, and aggressive salvage surgery have not been reliable methods of limiting local tumor recurrence or improving long-term cure rates. At present, highly stringent criteria for patient selection are recommended, yet such stringency decreases the utility of the procedure. What are needed are new approaches to an old problem. Novel strategies under evaluation include enhanced imaging modalities for lymph node metastases, neoadjuvant chemotherapy/radiation therapy, and more liberal use of immediate salvage resection for high-risk pathologic features. Molecular profiling of tumors with genetic markers and better integration of traditional and gene-targeted systemic therapy are promising approaches for the future. This review of the literature evaluates the recent successes and failures of local excision of rectal cancer and provides a current perspective on the expanded use of local excision without compromising care.

Therapy for unresectable recurrent and in-transit extremity melanoma.

BACKGROUND: Unresectable recurrent and in-transit extremity melanoma presents a dilemma for the treating physician. While the disease is confined to the involved limb, the survival mimics that of multiple nodal metastases, with a 10-year survival rate of approximately 40%. This represents late-stage disease for which curative treatment options are limited. METHODS: To review the current treatment strategies for stage IIIB (N2c) in-transit and recurrent melanoma focusing on the options for unresectable disease, MEDLINE was searched for studies of known and experimental treatments for in-transit and recurrent extremity melanoma. Further results were obtained after review of the initial citations. RESULTS: For unresectable recurrences and in-transit metastases, therapies are limited to palliative (radiation), local (intratumoral injection, laser ablation and electroporation), regional (isolated limb perfusion/infusion), and systemic (chemotherapy) when local or regional techniques are not feasible. CONCLUSIONS: In this patient population, intratumoral techniques have a limited role with current treatment regimens, but with the development of new drugs, these techniques may have more utility. If not contraindicated, regional techniques provide the greatest control and have minimal operative morbidity. Until new regimens are available, systemic therapy continues to be associated with considerable toxicity and only marginal response rates.

L576P KIT mutation in anal melanomas correlates with KIT protein expression and is sensitive to specific kinase inhibition.

Activating mutations in either BRAF or NRAS are seen in a significant number of malignant melanomas, but their incidence appears to be dependent to ultraviolet light exposure. Thus, BRAF mutations have the highest incidence in non-chronic sun damaged (CSD), and are uncommon in acral, mucosal and CSD melanomas. More recently, activating KIT mutations have been described in rare cases of metastatic melanoma, without further reference to their clinical phenotypes. This finding is intriguing since KIT expression is downregulated in most melanomas progressing to more aggressive lesions. In this study, we investigated a group of anal melanomas for the presence of BRAF, NRAS, KIT and PDGFRA mutations. A heterozygous KIT exon 11 L576P substitution was identified in 3 of 20 cases tested. The 3 KIT mutation-carrying tumors were strongly immunopositive for KIT protein. No KIT mutations were identified in tumors with less than 4+ KIT immunostaining. NRAS mutation was identified in one tumor. No BRAF or PDGFRA mutations were identified in either KIT positive or negative anal melanomas. In vitro drug testing of stable transformant Ba/F3 KIT(L576P) mutant cells showed sensitivity for dasatinib (previously known as BMS-354825), a dual SRC/ABL kinase inhibitor, and imatinib. However, compared to an imatinib-sensitive KIT mutant, dasatinib was potent at lower doses than imatinib in the KIT(L576P) mutant. These results suggest that a subset of anal melanomas show activating KIT mutations, which are susceptible for therapy with specific kinase inhibitors.