Evaluation of Immunotherapy in the Treatment of Melanoma

Clinical and molecular overview of immunotherapeutic approaches for malignant skin melanoma: Past, present and future

Traditional therapeutic approaches for malignant melanoma, have proved to be limited and/or ineffective, especially with respect to their role in improving patient survival and tumor recurrence. In this regard, immunotherapy has been demonstrated to be a promising therapeutic alternative, boosting antitumor responses through the modulation of cell signaling pathways involved in the effector mechanisms of the immune system, particularly, the so-called "immunological checkpoints". Clinical studies on the efficacy and safety of immunotherapeutic regimens, alone or in combination with other antitumor approaches, have increased dramatically in recent decades, with very encouraging results. Hence, this review will discuss the current immunotherapeutic regimens used to treat malignant melanoma, as well as the molecular and cellular mechanisms involved. In addition, current clinical studies that have investigated the use, efficacy, and adverse events of immunotherapy in melanoma will also be discussed.

Patient responses to ipilimumab, a novel immunopotentiator for metastatic melanoma: how different are these from conventional treatment responses?

Advanced melanoma has defied treatment advances for several decades. Immunotherapy with high-dose interleukin-2 or interferon-α has been beneficial in some cases, but significant toxicities limit its use. Cytotoxic T-lymphocyte antigen-4 (CTLA-4) signaling switches off T-cell activation and induces immune tolerance. Inhibiting CTLA-4 prolongs the antitumor T-cell response, reversing tolerance. Ipilimumab is a first-in-class anti-CTLA-4 monoclonal antibody, currently under review by the Food and Drug Administration for pretreated melanoma. Ipilimumab has shown durable responses and manageable toxicities in a large phase 3 clinical trial in patients with advanced melanoma. Variable response patterns have been observed, including: (1) response in baseline lesions; (2) a slow, steady decline in tumor burden; (3) response after an increase in tumor burden; and (4) response in index and new lesions accompanied by the appearance of other new lesions. Although responses (1) and (2) may be captured using standard methods, atypical responses (3) and (4) would be classified as progressive disease using conventional assessments. Patients on ipilimumab may have delayed responses or durable stable disease even after apparent disease progression, therefore using new immune-related response criteria is recommended to avoid premature treatment withdrawal. This review compares and contrasts responses to ipilimumab with those after chemotherapy, and discusses treatment implications.

Phase II Clinical Trial of a Granulocyte-Macrophage Colony-Stimulating Factor–Encoding, Second-Generation Oncolytic Herpesvirus in Patients With Unresectable Metastatic Melanoma

Purpose

Treatment options for metastatic melanoma are limited. We conducted this phase II trial to assess the efficacy of JS1/34.5-/47-/granulocyte-macrophage colony-stimulating factor (GM-CSF) in stages IIIc and IV disease.

Patients and Methods

Treatment involved intratumoral injection of up to 4 mL of 106pfu/mL of JS1/34.5-/47-/GM-CSF followed 3 weeks later by up to 4 mL of 108pfu/mL every 2 weeks for up to 24 treatments. Clinical activity (by RECIST [Response Evaluation Criteria in Solid Tumors]), survival, and safety parameters were monitored.

Results

Fifty patients (stages IIIc, n = 10; IVM1a, n = 16; IVM1b, n = 4; IVM1c, n = 20) received a median of six injection sets; 74% of patients had received one or more nonsurgical prior therapies for active disease, including dacarbazine/temozolomide or interleukin-2 (IL-2). Adverse effects were limited primarily to transient flu-like symptoms. The overall response rate by RECIST was 26% (complete response [CR], n = 8; partial response [PR], n = 5), and regression of both injected and distant (including visceral) lesions occurred. Ninety-two percent of the responses had been maintained for 7 to 31 months. Ten additional patients had stable disease (SD) for greater than 3 months, and two additional patients had surgical CR. On an extension protocol, two patients subsequently achieved CR by 24 months (one previously PR, one previously SD), and one achieved surgical CR (previously PR). Overall survival was 58% at 1 year and 52% at 24 months.

Conclusion

The 26% response rate, with durability in both injected and uninjected lesions including visceral sites, together with the survival rates, are evidence of systemic effectiveness. This effectiveness, combined with a limited toxicity profile, warrants additional evaluation of JS1/34.5-/47-/GM-CSF in metastatic melanoma. A US Food and Drug Administration–approved phase III investigation is underway.

Assessment of immunologic response and recurrence patterns among patients with clinical recurrence after vaccination with a preventive HER2/neu peptide vaccine: from US Military Cancer Institute Clinical Trials Group Study I-01 and I-02

BACKGROUND

E75, a HER2/neu immunogenic peptide, is expressed in breast cancer (BCa). We have performed clinical trials of E75 + GM-CSF vaccine in disease-free, node-positive and node-negative BCa patients at high recurrence risk and recurrences were noted in both control and vaccine groups.

METHODS

Among the 186 BCa patients enrolled, 177 completed the study. Patients were HLA typed; the HLA-A2(+)/A3(+) patients were vaccinated; HLA-A2(-)/A3(-) patients were followed as controls. Standard clinicopathological factors, immunologic response to the vaccine, and recurrences were collected and assessed.

RESULTS

The control group recurrence rate was 14.8 and 8.3% in the vaccinated group (P = 0.17). Comparing the 8 vaccinated recurrences (V-R) to the 88 vaccinated nonrecurrent patients (V-NR), the V-R group had higher nodal stage (> or = N2: 75 vs. 5%, P = 0.0001) and higher grade tumors (%grade 3: 88 vs. 31%, P = 0.003). The V-R group did not fail to respond immunologically as noted by equivalent dimer responses and post-DTH responses. Compared to control recurrent patients (C-R), V-R patients trended toward higher-grade tumors and hormone-receptor negativity. C-R patients had 50% bone-only recurrences, compared to V-R patients with no bone-only recurrences (P = 0.05). Lastly, V-R mortality rate was 12.5% compared with 41.7% for the C-R group (P = 0.3).

CONCLUSIONS

The vaccinated patients who recurred had more aggressive disease compared to V-NR patients. V-R patients had no difference in immune response to the vaccine either in vitro or in vivo. V-R patients, when compared to C-R patients, trended towards more aggressive disease, decreased recurrence rates, decreased mortality, and no bone-only recurrences.