Insights into Local Tumor Microenvironment Immune Factors Associated with Regression of Cutaneous Melanoma Metastases by Mycobacterium bovis Bacille Calmette-Guérin.

Mycobacterium bovis bacille Calmette-Guérin (BCG) is listed as an intralesional (IL) therapeutic option for inoperable stage III in-transit melanoma in the National Comprehensive Cancer Network Guidelines. Although the mechanism is unknown, others have reported up to 50% regression of injected lesions, and 17% regression of uninjected lesions in immunocompetent patients after direct injection of BCG into metastatic melanoma lesions in the skin. BCG and other mycobacteria express ligands capable of stimulating the γ9δ2 T cells. Therefore, we hypothesized that γ9δ2 T cells play a role in promoting BCG-mediated antitumor immunity in patients treated with IL-BCG for in-transit cutaneous melanoma metastases. Indeed, we found γ9δ2 T cell infiltration in melanoma skin lesions during the course of IL-BCG treatment. Gene expression analysis revealed that BCG injection elicits the expression of a vast array of chemokines in tumor lesions, including strong expression of CXCL9, 10, and 11, a set of chemokines that attract T cells expressing the CXCR3 chemokine receptor. In corroboration with our hypothesis, approximately 85% of γδ T cells express high levels of CXCR3 on their surface. Importantly, the injected tumor lesions also express genes whose protein products are the antigenic ligands for γδ T cells (BTN3A1 and MICB), and the cytokines that are the typical products of activated γδ T cells. Interestingly, we also found that γδ T cells infiltrate the regressed lesions that did not receive BCG injections. Our study suggests that γ9δ2 T cells may contribute to melanoma regression induced by IL-BCG treatment.

Treatment of melanoma metastases in a limb by isolated limb perfusion and isolated limb infusion.

In-transit melanoma metastases are often confined to a limb. In this circumstance, treatment by isolated limb perfusion or isolated limb infusion can be a remarkably effective regional treatment option.

A Comparison of 3 tumor markers (MIA, TA90IC, S100B) in stage III melanoma patients.

PURPOSE: There is no consensus regarding the optimal tumor markers for melanoma. We compared 3 tumor markers, TA90-immune complex (TA90IC), melanoma-inhibiting activity (MIA) protein, and S100B protein in Stage III melanoma patients undergoing adjuvant vaccine immunotherapy. EXPERIMENTAL DESIGN: The serum of 75 patients representing 3 prognostic cohorts was assayed for the tumor markers prior to initiating immunotherapy and at 6 follow-up time points. Upper limits of normal for TA90IC, MIA and S100B were set at OD 0.41, 8.5 ng/ml, and 2.5 microg/l, respectively. RESULTS: At least 1 marker became elevated prior to 41 (80 percent) of 51 recurrences. TA90IC was the earliest elevated marker in 29 (57 percent), MIA in 11 (22 percent), and S100B in 4 (8 percent). Multivariate regression analysis revealed that TA90IC was an independent predictor of survival when elevation occurred between 2 weeks and 3 months, whereas MIA was an independent predictor at 4-6 months. In the poor prognostic cohort, mean values for MIA and S100B increased progressively, whereas TA90IC exhibited a parabolic curve. CONCLUSION: In this patient population, TA90IC and MIA were complementary; elevation of the immune complex preceded elevation of the tumor antigen in patients who developed recurrence. Additional studies in populations not receiving vaccine will further clarify the clinical utility of these assays.