Modulation of signal transducers and activators of transcription 1 and 3 signaling in melanoma by high-dose IFNalpha2b

PURPOSE

The Janus-activated kinase/signal transducers and activators of transcription (STAT) pathway of IFN signaling is important to immunoregulation and tumor progression. STAT1 plays a prominent role in the effector immune response, whereas STAT3 is implicated in tumor progression and down-regulation of the response to type I IFNs. The goal of this study was to understand the effects of high-dose IFNalpha2b (HDI) in relation to the balance of pSTAT1 and pSTAT3.

EXPERIMENTAL DESIGN

We evaluated STAT1 and STAT3 jointly as mediators of IFNalpha effects in the setting of a prospective neoadjuvant trial of HDI, in which tissue samples were obtained before and after 20 doses of HDI therapy. Double immunohistochemistry for pSTAT1 and pSTAT3 was done on paired fixed (9 patients) or frozen (12 patients) biopsies.

RESULTS

HDI was found to up-regulate pSTAT1, whereas it down-regulates pSTAT3 and total STAT3 levels in both tumor cells and lymphocytes. Higher pSTAT1/pSTAT3 ratios in tumor cells pretreatment were associated with longer overall survival (P = 0.032). The pSTAT1/pSTAT3 ratios were augmented by HDI both in melanoma cells (P = 0.005) and in lymphocytes (P = 0.022). Of the immunologic mediators and markers tested, TAP2 was augmented by HDI (but not TAP1 and MHC class I/II).

CONCLUSION

IFNalpha2b significantly modulates the balance of STAT1/STAT3 in tumor cells and host lymphocytes, leading to up-regulation of TAP2 and augmented host antitumor response. The pSTAT1/pSTAT3 ratio in tumor cells at baseline may serve as a useful predictor of clinical outcome in cutaneous melanoma; the modulation of this ratio may serve as a predictor of therapeutic effect.

Strategies for the Development of More Effective Adjuvant Therapy of Melanoma: Current and Future Explorations of Antibodies, Cytokines, Vaccines, and Combinations

Adjuvant trials have evaluated the influence of multiple agents on relapse and mortality for patients with intermediate-risk (stage IIA, American Joint Committee on Cancer staging manual, 6th ed.), high-risk (stage IIB-III), or very high-risk (stage IIIB-IV) operable melanoma. A 25% to 33% reduction of relative relapse risk with high-dose IFN-alpha2b therapy has been documented in stage groups overall, with survival prolongation in two of these trials. In contrast, no large cooperative group trial has ever shown a significant prolongation of survival for inoperable advanced stage IV melanoma. The basis for the failure of therapies in advanced disease may lie in differences in the immune function of patients with active metastatic stage IV disease. These observations argue for the exploration of promising new therapies in adjuvant settings. Past adjuvant studies have targeted stage IIB-III patients, focusing less on the more advanced but resectable stage IIIB and IV (M(1a-b)) disease groups. Current chemobiotherapy (S0008) and granulocyte-macrophage colony-stimulating factor plus peptide vaccination (E4697) trials have now evaluated the higher-risk disease groups where trials may soon be expected to yield results. Predictive markers that would allow us to focus treatment on those patients who are most likely to respond would accelerate our development of adjuvant therapy for melanoma. We have recently developed a neoadjuvant approach to high-dose IFN in which the molecular and immunologic effects of IFN have been correlated with clinical antitumor effects of this therapy. In addition, the Hellenic Oncology group has shown that the benefit of high-dose IFN is closely correlated with serologic and clinical manifestations of autoimmunity. These new insights will allow us to develop more efficient approaches to adjuvant therapy of melanoma, focusing on autoimmunity and antitumor immunity with new immunomodulators, such as anti-CTLA4 antibodies and vaccination.