Alternating recombinant human interleukin-2 and dacarbazine in advanced melanoma. A multicentric phase II study

Alternating chemo-immunotherapy with temozolomide and low-dose interleukin-2 in patients with metastatic melanoma

Temozolomide is a rapidly absorbed chemotherapeutic agent, achieving significant central nervous system penetration. Previous clinical trials suggested that temozolomide in sequence with low-dose recombinant human interleukin-2 might be an efficacious and relatively non-toxic chemo-immunotherapeutic treatment, which may synergistically eliminate tumours. The primary objective was to determine the safety and tolerance of temozolomide administered orally 200 mg/m days 1-5, in sequential combination with subcutaneous injections of 4.5x10 IU recombinant human interleukin-2 on days 8-11, 15-18 and 22-25 in patients with measurable, progressive metastatic malignant melanoma without radiological signs of central nervous system metastases. The secondary objectives were to determine tumour response and time to progression. Twenty-seven patients were included, of which four were non-evaluable for response. Twenty-three patients tolerated the regimen with side effects below grade 3 according to the World Health Organization (WHO) scale. Three patients suspended the treatment because of WHO grade 3 side effects already during the first 3 days of the first course of temozolomide. Seven patients showed no tumour progression during the first four treatment cycles. Two patients had complete responses, three partial responses and two stable disease at the end of the four cycles defined by the protocol and they continued the treatment until signs of relapse or a maximum of 21 courses. Five of these patients are still alive. Thrombocytopenia was significantly more pronounced in patients with objective response and stable disease than in non-responders to therapy. The median time to progression for all patients was 3.1 months and for responding and stable disease patients was 15 months. Five of 23 treated patients (22%) developed brain metastases during follow-up. Temozolomide in combination with recombinant human interleukin-2 is a well-tolerated regimen for outpatient treatment and the bio-chemotherapy combination induced durable clinical responses. Thrombocytopenia might be a positive predictive factor for response to therapy.

Biochemotherapy of melanoma

Despite the evaluation of many different chemotherapy and immunotherapy drugs, the median survival in metastatic melanoma remains in the range of 6 to 9 months. Combination chemotherapy or combination immunotherapy has not produced a significant advantage over single-agent therapy but is associated with greater toxicity. Based on the potential for additive or synergistic activity with the combination of chemotherapy and biotherapy, many investigators have evaluated biochemotherapy in patients with advanced melanoma. Aggregate results suggest that biochemotherapy is tolerable and produces a response rate in the range of 50% with a complete response rate of 10%. Although these phase II results appear superior to previous results with chemotherapy or immunotherapy alone, the true benefits of biochemotherapy can only be determined with the results of randomized phase III trials; therefore, biochemotherapy should be considered an as yet experimental therapy. Many other issues regarding biochemotherapy, such as sequence, outpatient administration, and use in the adjuvant setting, for stage III melanoma are being actively evaluated.

Pharmacological elements in clinical application of synthetic peptides

The research carried out on the biological properties of synthetic peptides and the possibility of obtaining them in adequate amounts through the recombinant DNA technology allows their use as therapeutical agents. Procedures following the synthesis of peptides must be performed in order to verify their structure, conformation, immunogenicity and biological activity and to make them suitable for clinical applications. The size of synthetic peptides together with some modifications such as amidation, acetylation and sulfatation must be taken into consideration as they may have a significant impact on half-life, stability and biological activity. Endothelial, epithelial and enzymatic interference which may hinder the absorption of drugs must be evaluated in order to choose the most appropriate route of administration. The considerable bioavailability related to the intravenous route, the effectiveness of the circulation of the intramuscular route and the possibility of reaching specific targets by the intra-arterial route must also be taken into consideration. There is the possibility of applying transdermal therapeutic systems and transdermal iontophoresis only for peptides of low molecular weight. Among synthetic peptides provided with antianaemic activity, erythropoietin, growth factors and interleukin 3 must be mentioned because of their effectiveness both in optimal stimulation of melopoiesis after chemotherapy or bone-marrow transplantation and in the treatment of anaemia occurring during chronic renal failure. Furthermore, interferon alpha was shown to be one of the most used synthetic peptides provided with antiviral and antineoplastic activity. Remarkable results have been obtained in the treatment of chronic hepatitis C, haematological malignancies and some solid tumours. More recently, interleukin 2 has been tested in the treatment of melanoma and renal cancer, inducing a reasonable proportion of overall response rate. Finally, the antagonist of gonadotropin-releasing-hormone may be regarded as effective agent both in the treatment of prostate cancer and in the inhibition of luteinizing-hormone surges during controlled ovarian stimulation. Toxic side effects can be related to the administered dose as well as to metabolites derived from bacteria in which peptides have been synthesized.

Biochemotherapy for melanoma

Systemic therapy for advanced melanoma includes chemotherapy, either with dacarbazine (DTIC) alone or a multiagent combination chemotherapy, and biologic therapy with recombinant interferon-alpha and/or interleukin-2. However, none of these treatment options has produced long-term control of the disease except on rare occasions. Combined chemo-immunotherapy (biochemotherapy) has shown high objective response rates (approximately 50%) and a significant though small proportion of long-term complete responders in metastatic melanoma. It has, however, been associated with greater toxicity. Overall results of sequential versus concurrent biochemotherapy are similar, but the toxicity appears to be less severe in patients treated with the concurrent regimen. At this time, biochemotherapy is under evaluation in a well-designed prospective, randomized trial to identify whether there is benefit to this strategy, compared with chemotherapy alone.

Interleukin 2 therapy: current role in surgical oncological practice

The use of recombinant interleukin 2 (rIL-2) in clinical practice has opened up new and beneficial avenues in the treatment of certain malignant diseases. Although rIL-2 can stimulate a range of host antitumour defence mechanisms, only 30-40 per cent of patients who are treated will respond to such therapy as assessed by a reduction in tumour volume. The effect of rIL-2-based treatment schedules on delaying progression of disease and on overall survival in comparison with standard current treatments and chemotherapeutic regimens is not clear. Randomized clinical trials are required to evaluate precisely the role of rIL-2 in various therapeutic combinations and to ascertain the optimum therapeutic regimens for individual tumour types. Studies currently under way should provide more insight into the possible beneficial effects of immunotherapy with rIL-2. More basic research is required to ascertain how rIL-2 may produce its antitumour effects and why the therapeutic results obtained in humans have been so selective and less beneficial than those in experimental animals.

Chemoimmunotherapy of metastatic malignant melanoma. The Salpétrière Hospital (SOMPS) experience

Optimistic results were obtained in the treatment of 39 patients with surgically incurable metastatic malignant melanoma using a regimen including 2 to 3 monthly induction cycles of cis-diamminedichloroplatinum (CDDP), recombinant interleukin-2 (rIL-2) and interferon alpha-2a (IFN alpha-2a). 33 of 39 patients were pretreated with chemotherapy (dacarbazine and/or fotemustine:31, CDDP:6) and 17 of 39 with IFN alpha-2a. Overall response rate was 54% with 13% achieving a complete response for up to 59+ weeks. Moderate to severe side-effects were reversible on rIL-2 cessation and toxicity was manageable in a routine inpatient setting. These results are especially encouraging as they were seen in previously treated patients, classically low responders, including 3 who were resistant to cisplatin or other platinum complexes. The question remains if this regimen bypasses traditional mechanisms of drug resistance.