Reinduction of PD1-inhibitor therapy: first experience in eight patients with metastatic melanoma

Significant progress has been made in the treatment of metastatic melanoma during the last years. Approval of immune-checkpoint inhibitors and targeted therapies has been achieved recently. The sequencing of these therapies is an important issue. Here, we report our experience with the treatment and retreatment with PD1-inhibitors (PD1i) in eight patients. The patients (two female and seven male with a median age of 70 years, all melanoma stage IV, M1c) underwent a first treatment period with PD1i for a median of 5.5 months. Three (37.5%) patients had a stable disease as best response, two (25%) showed progression, two (25%) showed partial response, and one (12.5%) achieved complete remission. PD1i was discontinued due to disease progression in seven patients and due to side effects (pancreatitis) in one patient. Patients were subsequently treated with ipilimumab (n=2), or chemotherapy (n=4), or no other medical treatment (n=2). All eight patients were subsequently retreated with PD1i for a median of 2.5 months. One (12.5%) developed a partial response, whereas in three patients (37.5%) the disease was stabilized. PD1i have shown a high and durable response rate in the first-line treatment of metastatic melanoma. Our study suggests PD1i retreatment as a reasonable option for selected patients. Further investigations are needed to verify the value of PD1i re-exposure and to identify subgroups of patients who can benefit.

Phase III randomized clinical trial comparing tremelimumab with standard-of-care chemotherapy in patients with advanced melanoma

PURPOSE

In phase I/II trials, the cytotoxic T lymphocyte-associated antigen-4-blocking monoclonal antibody tremelimumab induced durable responses in a subset of patients with advanced melanoma. This phase III study evaluated overall survival (OS) and other safety and efficacy end points in patients with advanced melanoma treated with tremelimumab or standard-of-care chemotherapy.

PATIENTS AND METHODS

Patients with treatment-naive, unresectable stage IIIc or IV melanoma were randomly assigned at a ratio of one to one to tremelimumab (15 mg/kg once every 90 days) or physician's choice of standard-of-care chemotherapy (temozolomide or dacarbazine).

RESULTS

In all, 655 patients were enrolled and randomly assigned. The test statistic crossed the prespecified futility boundary at second interim analysis after 340 deaths, but survival follow-up continued. At final analysis with 534 events, median OS by intent to treat was 12.6 months (95% CI, 10.8 to 14.3) for tremelimumab and 10.7 months (95% CI, 9.36 to 11.96) for chemotherapy (hazard ratio, 0.88; P = .127). Objective response rates were similar in the two arms: 10.7% in the tremelimumab arm and 9.8% in the chemotherapy arm. However, response duration (measured from date of random assignment) was significantly longer after tremelimumab (35.8 v 13.7 months; P = .0011). Diarrhea, pruritus, and rash were the most common treatment-related adverse events in the tremelimumab arm; 7.4% had endocrine toxicities. Seven deaths in the tremelimumab arm and one in the chemotherapy arm were considered treatment related by either investigators or sponsor.

CONCLUSION

This study failed to demonstrate a statistically significant survival advantage of treatment with tremelimumab over standard-of-care chemotherapy in first-line treatment of patients with metastatic melanoma.

Ipilimumab: unleashing the power of the immune system through CTLA-4 blockade

Malignant melanoma is rising faster in incidence than any other malignancy. Long-term remission or "cure" is rare and is almost exclusively limited to therapies that stimulate an immune antitumor response. Ipilimumab is a novel targeted human immunostimulatory monoclonal antibody that blocks cytotoxic T-lymphocyte antigen4 (CTLA-4), an immune-inhibitory site expressed on activated T cells. Ipilimumab is well tolerated as an outpatient infusion therapy. Multiple studies have confirmed significant antimelanoma activity. A randomized trial has documented a survival benefit when ipilimumab was compared to a gp-100 vaccine only arm. The unique mechanism of action of ipilimumab makes assessment of response by conventional criteria difficult. Benefit from ipilimumab can occur after what would be considered progression with World Health Oganization (WHO) or Response Evaluation Criteria in Solid Tumors (RECIST) criteria. New immune response criteria have been proposed. Therapeutic responses peak between 12 and 24 weeks, with slow responses continuing up to and beyond 12 months. The major drug- related adverse side effects (10%-15% grade 3 or above) are immune-related and consist most commonly of rash, colitis, hypophysitis, thyroiditis, and hepatitis. Colonic perforation can occur and patients with diarrhea have to be monitored carefully with strict adherence to treatment algorithms. Algorithms for the treatment of other adverse side effects have been developed. The treatment of immune-related side effects with immunosuppressive agents, such as corticosteroids, does not appear to impair antitumor response. With proper monitoring and management of side effects, ipilimumab is an extremely safe drug to administer. The benefits of ipilimumab will most certainly extend to other malignancies in the near future.