Rationale and Clinical Results of Multi-target Treatments in Oncology

During the last 10 years, the concept of targeted biological therapy for the treatment of cancer has emerged. Targeted agents entered clinical practice only recently, and the first drugs with demonstrated clinical efficacy were mainly inhibitors of the ErbB family of receptors (i.e., EGFR and HER-2), either monoclonal antibodies (MAbs) or tyrosine kinase inhibitors (TKIs). After the proof of concept for the clinical efficacy and tolerability of these selective agents, it was conceived that most tumors will depend on more than one signaling pathway for their growth and survival. As a consequence, different strategies were pursued to inhibit multiple signaling pathways or multiple steps in the same pathway, either by the development of multi-targeted agents or the combination of single targeted drugs. The recent FDA and EMEA approval of sorafenib and sunitinib, both multi-targeted TKIs, marked the coming of age of this new generation of drugs. Now a whole new wave of multi-targeted compounds is moving into clinical trials, raising in the minds of investigators important questions about the best strategies to pursue in their use and many doubts about their differences and the seeming redundancies in the pipelines of pharmaceutical companies. This review will deal with the rationale underlying the multi-targeted approach and with the available clinical experience with multi-targeted agents, especially focusing on molecules with anti-EGFR mechanisms of action.

Sorafenib in combination with erlotinib or with gemcitabine in elderly patients with advanced non-small-cell lung cancer: a randomized phase II study

BACKGROUND

Sorafenib is a small-molecule multitargeted kinase inhibitor that blocks the activation of C-RAF, B-RAF, c-KIT, FLT-3, RET, vascular endothelial growth factor receptor 2 (VEGFR-2), VEGFR-3 and platelet-derived growth factor receptor β. The aim of this multicenter, randomized phase II study was to evaluate clinical activity and safety of sorafenib in combination with erlotinib or gemcitabine in unselected untreated elderly patients with non-small-cell lung cancer (NSCLC).

METHODS

The trial was designed to select the most promising sorafenib-containing combination in previously untreated elderly (≥70 years) stage IIIB or IV NSCLC patients, with performance status of zero to two. Patients were randomly assigned to one of the following combinations: gemcitabine, 1200 mg/m(2) days 1 and 8, every 21 days, for a maximum of six cycles, plus sorafenib, 800 mg/day, until disease progression or unacceptable toxicity (arm 1); or erlotinib, 150 mg/day, plus sorafenib, 800 mg/day, until disease progression or unacceptable toxicity (arm 2). A selection design was applied with 1-year survival rate as the primary end point of the study, requiring 58 patients.

RESULTS

Sixty patients were randomly allocated to the study (31 patients in arm 1 and 29 patients in arm 2). After a median follow-up of 15 months, 10 patients [32%, 95% confidence interval (CI) 16% to 49%] in arm 1 and 13 patients (45%, 95% CI 27% to 63%) in arm 2 were alive at 1 year. Median overall survival was 6.6 and 12.6 months in arm 1 and arm 2, respectively. Observed toxic effects were consistent with the expected drug profiles.

CONCLUSIONS

The combination of erlotinib and sorafenib was feasible in elderly patients with advanced NSCLC and was associated with a higher 1-year survival rate than the other arm. According to the selection design, this combination warrants further investigation in phase III trials.

Cetuximab for treatment of metastatic colorectal cancer

In the past decade the median overall survival of patients with metastatic colorectal cancer has increased from 12 to more than 20 months, mostly due to the new chemotherapeutic agents, irinotecan and oxaliplatin. Most recently, targeted therapies, that inhibit specific cancer pathways and molecules, have shown promising results in the treatment of patients with metastatic colorectal cancer and other solid tumors. One of the most studied targets for anticancer therapy is the epidermal growth factor receptor (EGFR), which is overexpressed in a variety of malignancies. Cetuximab, an anti-EGFR chimeric monoclonal antibody, has shown clinically meaningful antitumor activity in patients with metastatic colorectal cancer in several clinical trials. Efforts of physicians and researchers are currently directed towards the identification of predictive factors (clinical or molecular) of clinical outcome, with the aim of both optimizing the therapeutic index and dealing with increasing costs of these new compounds.

Rationale and clinical results of multi-target treatments in oncology

During the last 10 years, the concept of targeted biological therapy for the treatment of cancer has emerged. Targeted agents entered clinical practice only recently, and the first drugs with demonstrated clinical efficacy were mainly inhibitors of the ErbB family of receptors (i.e., EGFR and HER-2), either monoclonal antibodies (MAbs) or tyrosine kinase inhibitors (TKIs). After the proof of concept for the clinical efficacy and tolerability of these selective agents, it was conceived that most tumors will depend on more than one signaling pathway for their growth and survival. As a consequence, different strategies were pursued to inhibit multiple signaling pathways or multiple steps in the same pathway, either by the development of multi-targeted agents or the combination of single targeted drugs. The recent FDA and EMEA approval of sorafenib and sunitinib, both multi-targeted TKIs, marked the coming of age of this new generation of drugs. Now a whole new wave of multi-targeted compounds is moving into clinical trials, raising in the minds of investigators important questions about the best strategies to pursue in their use and many doubts about their differences and the seeming redundancies in the pipelines of pharmaceutical companies. This review will deal with the rationale underlying the multi-targeted approach and with the available clinical experience with multi-targeted agents, especially focusing on molecules with anti- EGFR mechanisms of action.

Biomodulation of cancer chemotherapy for metastatic colorectal cancer: a randomized study of weekly low-dose irinotecan alone versus irinotecan plus the oncostatic pineal hormone melatonin in metastatic colorectal cancer patients progressing on 5-fluorouracil-containing combinations

Recent advances in immunobiological knowledge have suggested the possibility of enhancing the therapeutic activity of various chemotherapeutic agents by a concomitant administration of anti-oxidant drugs and/or immunomodulating neurohormones. In particular, the pineal neurohormone melatonin (MLT), which is able to exert both antioxidant and immunomodulating effects, has been proven to enhance the efficacy of various chemotherapeutic drugs, namely cisplatin, anthracyclines and 5-fluorouracil, whereas at present there are no data about its possible influence on cytotoxic drugs effective in the treatment of colon cancer other than 5-fluorouracil, such as irinotecan (CPT-11). The present study was performed to evaluate the influence of a concomitant administration of MLT on CPT-11 therapeutic activity in metastatic colorectal cancer. The study included 30 metastatic colorectal cancer patients progressing after at least one previous chemotherapeutic line containing 5-fluorouracil, who were randomized to be treated with CPT-11 alone or CPT-11 plus MLT. According to a weekly low-dose schedule, CPT-11 was given i.v. at 125 mg/m2/week for 9 consecutive weeks. MLT was administered orally at 20 mg/day during the dark period of the day. No complete response was observed. A partial response (PR) was achieved in 2 out of 16 patients treated with CPT-11 alone and in 5 out of 14 patients concomitantly treated with MLT. Moreover, a stable disease (SD) was obtained in 5 out of 16 patients treated with CPT-11 alone and in 7 out of 14 patients treated with CPT-11 plus MLT. Therefore, the percent of disease-control achieved in patients concomitantly treated with MLT was significantly higher than that observed in those treated with chemotherapy alone (12 out of 14 vs 7 out of 16, p < 0.05). The only important toxicity was diarrhoea grade 3-4, which occurred in 6 out of 16 patients treated with CPT-11 alone and in 4 out of 14 patients treated with CPT-11 plus MLT, which required a 50% dose reduction. However, taken together, patients treated with CPT-11 at 50% of the planned dose showed a percent of disease control comparable to that achieved in patients who had no dose reduction (6 out of 10 vs 13 out of 20). This preliminary study shows that the efficacy of weekly low-dose CPT-11 in pretreated metastatic colorectal cancer patients may be enhanced by a concomitant daily administration of the pineal hormone MLT, according to the results previously reported for other chemotherapeutic agents. Moreover, since the dose reduction of CPT-11 does not influence its efficacy, the dose of CPT-11 for successive studies might be not greater than 70 mg/m2.