Randomized phase III trial comparing bexarotene (L1069-49)/cisplatin/vinorelbine with cisplatin/vinorelbine in chemotherapy-naive patients with advanced or metastatic non-small-cell lung cancer: SPIRIT I

PURPOSE

This study evaluated whether the combination of the synthetic rexinoid bexarotene with first-line cisplatin/vinorelbine therapy provides additional survival benefit in patients with advanced non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

Patients with stage IIIB with pleural effusion or stage IV NSCLC and Eastern Cooperative Oncology Group performance status 0 to 1 were randomly assigned to open-label bexarotene 400 mg/m(2)/d with cisplatin/vinorelbine or to cisplatin/vinorelbine alone. Antilipid agents were initiated on or before day 1 in the bexarotene arm. Primary efficacy end point was overall survival. Primary, secondary and supportive efficacy analyses were conducted.

RESULTS

A total of 623 patients (312 control, 311 bexarotene) were enrolled. Overall, no significant difference in survival occurred between the two treatment groups. However, an unplanned retrospective analysis showed that a subpopulation of bexarotene patients (n = 98 of 306) who experienced National Cancer Institute grade 3/4 hypertriglyceridemia had longer median survival compared with control patients (12.3 v 9.9 months; log-rank P = .08). Within that subgroup, those who benefited the most included males, smokers, those with stage IV disease, and those with a 6-month prior weight loss of 5% or more. Incidence, type and severity of grade 3/4 adverse events were comparable between arms, except for leukopenia (higher in chemotherapy arm) and hyperlipemia, hypothyroidism, dyspnea, and headache (higher in chemotherapy/bexarotene arm).

CONCLUSION

The addition of bexarotene to first-line chemotherapy did not increase survival in patients with advanced NSCLC. However, a subgroup (32%) of bexarotene-treated patients developing high-grade hypertriglyceridemia appeared to have better survival (12.3 months) than controls; thus triglyceride response may be a biomarker of survival benefit with bexarotene.

Phase III Trial Comparing Carboplatin, Paclitaxel, and Bexarotene With Carboplatin and Paclitaxel in Chemotherapy-Naïve Patients With Advanced or Metastatic Non–Small-Cell Lung Cancer: SPIRIT II

Purpose

The purpose of this study was to determine whether addition of the synthetic rexinoid bexarotene (Targretin; Eisai Inc, Woodcliff Lake, NJ) to standard first-line carboplatin and paclitaxel therapy provides additional survival benefit in patients with advanced non–small-cell lung cancer (NSCLC).

Patients and Methods

Patients with stage IIIB disease with pleural effusion, or stage IV NSCLC and Eastern Cooperative Oncology Group performance status 0 to 1, were randomly assigned to bexarotene 400 mg/m2/d combined with carboplatin and paclitaxel, or assigned to carboplatin and paclitaxel alone. Bexarotene patients also received lipid-lowering agents on or before day 1. The primary efficacy end point was overall survival; secondary efficacy and supportive analyses were also conducted.

Results

A total of 612 patients (306 per arm) were enrolled onto the study. In the intent-to-treat population, no significant difference in survival occurred between the two arms. However, a subpopulation (approximately 40%) of bexarotene-treated patients who experienced National Cancer Institute grade 3/4 hypertriglyceridemia had significantly longer median survival than control patients (12.4 v 9.2 months; log-rank, P = .014). Bexarotene-treated patients with grade 3/4 hypertriglyceridemia who received the most benefit included those who were male, were smokers, experienced 6-month prior weight loss ≥ 5%, and had stage IV disease. The incidence and severity of most adverse events were similar between arms, although hyperlipidemia, neutropenia, fatigue, leukopenia, arthralgia, and diarrhea were more frequent in the bexarotene arm.

Conclusion

Although the addition of bexarotene to chemotherapy did not improve survival in the overall study population, occurrence of high-grade hypertriglyceridemia in bexarotene-treated patients strongly correlated with increased survival, suggesting that bexarotene may benefit a segment of first-line NSCLC patients.

Definitive Chemoradiation for the Treatment of Locally Advanced Non–Small-Cell Lung Cancer

A third of patients with newly diagnosed non–small-cell lung cancer (NSCLC) have locally advanced disease not amenable for curative resection. Addition of chemotherapy to thoracic radiation improves survival in patients with locally advanced NSCLC when compared with thoracic radiation alone. Over the past two decades, we have made slow but steady progress in improving the outcomes of therapy in this subset of patients. This review summarizes the past two decades of research and outlines the direction we need to pursue to significantly enhance the outcomes. The widespread use of positron emission tomography (identifying those with occult distant metastatic disease and sparing them combined-modality therapy), improved radiation techniques, and better supportive care resulting in improved chemotherapy delivery have resulted in improved outcomes. There is considerable interest in studying the role of higher doses of thoracic radiation (74 Gy) in this disease, and this is the subject of an ongoing intergroup study. Despite some recent setbacks, molecularly targeted therapies need to be studied carefully in combination with chemoradiotherapy. There is an urgent need to develop regimens that incorporate chemotherapy agents that can be administered at doses that are systemically active and yet tolerable.

Uncovering novel targets for cancer chemoprevention

Tobacco carcinogen treatment of immortalized human bronchial epithelial (HBE) cells has uncovered novel targets for cancer chemoprevention. Experiments were conducted with HBE cells and independent treatments with tobacco carcinogens along with the chemopreventive agent all-trans-retinoic acid (RA). That work highlighted D-type and E-type cyclins as novel molecular pharmacologic targets of several chemopreventive agents. G1 cyclins are often aberrantly expressed in bronchial preneoplasia and lung cancers. This implicated these species as targets for clinical cancer chemoprevention. Retinoid regulation mechanisms of D-type cyclins in lung cancer chemoprevention have been comprehensively explored. Retinoid chemoprevention has been mechanistically linked to proteasomal degradation of cyclin D1 and cyclin D3. Threonine 286 mutation stabilized cyclin D1, implicating phosphorylation in this retinoid chemoprevention. Studies with a phospho-specific anti-cyclin D1 antibody confirmed this hypothesis. Glycogen synthase kinase (GSK) inhibitors established a role for this kinase in the retinoid regulation of cyclin D1, but not cyclin D3. Involvement of D-type cyclins in this chemoprevention was shown using small interfering RNAs (siRNAs). Gene profiling experiments highlighted the E1-like ubiquitin-activating enzyme (UBE1L) in the retinoid regulation of cyclin D1. Proof of principle trials have translated these studies into the clinic and established that chemopreventive agents can target D-type cyclins. These findings have been built upon with a targeted combination regimen that cooperatively affects D-type cyclins. Taken together, these preclinical and clinical findings strongly implicate these cyclins as novel molecular pharmacological targets for cancer chemoprevention.

Plasma and cerebrospinal fluid pharmacokinetics of intravenously administered ABT-751 in non-human primates

PURPOSE

ABT-751 is an orally bioavailable sulfonamide that binds to the colchicine binding site on beta-tubulin and inhibits microtubule polymerization. The plasma and cerebrospinal fluid (CSF) pharmacokinetics of ABT-751, after a short intravenous infusion, were evaluated in a non-human primate (Macaca mulatta) model that is highly predictive of the CSF penetration of drugs in humans.

MATERIALS AND METHODS

Plasma and CSF samples were collected over 24 h after 7.5 mg/kg (150 mg/m2) ABT-751 infused over 0.25-0.70 h, and ABT-751 concentrations in plasma and CSF were quantified using a validated HPLC-MS/MS assay. Pharmacokinetic parameters in plasma and CSF were derived using non-compartmental methods.

RESULTS AND CONCLUSION

Plasma disappearance was bi-exponential with a terminal half-life of 13 h. The mean +/- SD clearance was 100 +/- 18 ml/min m2, the mean +/- SD volume of distribution at steady state was 1.3 +/- 0.5 l/kg, and the mean +/- SD mean residence time was 4.6 +/- 1.8 h. The mean +/- SD peak ABT-751 concentration in CSF was 0.26 +/- 0.08 microM, and the mean +/- SD CSF half-life of 1.3 +/- 0.3 h. CSF penetration was limited (mean +/- SD AUC(CSF):AUC(plasma), 1.1 +/- 0.3%) relative to total (protein-bound + free) plasma drug concentrations, but the CSF concentrations approximated the estimated free drug concentrations in plasma.

Bexarotene and erlotinib for aerodigestive tract cancer

PURPOSE

The epidermal growth factor receptor (EGFR) and cyclin D1 are overexpressed in lung carcinogenesis. The rexinoid, bexarotene, represses cyclin D1 and EGFR expression in vitro. It was hypothesized that combining bexarotene with the EGFR inhibitor, erlotinib, would augment clinical activity.

PATIENTS AND METHODS

In vitro studies and a phase I clinical trial were performed. Twenty-four patients with advanced aerodigestive tract cancers were enrolled; 79% had non-small-cell lung cancer (NSCLC). The primary objective was to determine the maximum-tolerated dose. Clinical activity was a secondary objective.

RESULTS

Combining erlotinib with bexarotene enhanced growth suppression in vitro compared with each single-agent treatment. This cooperatively repressed cyclin D1 expression. Clinically, the most frequent toxicities were mild hypertriglyceridemia and skin rash. Two serious treatment-related adverse events occurred (creatine phosphokinase elevation attributed to antilipid therapy and a case of generalized pain). Five objective responses (four partial and one minor) were observed in NSCLC patients. Responses were observed in males and smokers. EGFR sequence analyses did not reveal activating mutations in tumors from assessable responding patients. Median time to progression was 2.0 months; overall survival time was 14.1 months; and 1-year survival rate was 73.8%.

CONCLUSION

The recommended phase II doses are erlotinib 150 mg/d and bexarotene 400 mg/m2/d orally. These agents can be administered in combination at the recommended single-agent doses without added toxicity. Overall survival and clinical features of responding patients differ from prior reports of single-agent erlotinib treatment. These findings are encouraging and warrant further investigation of this regimen.

Treatment of locally advanced non-small cell lung cancer in the elderly

PURPOSE OF REVIEW

Non-small cell lung cancer (NSCLC) may be considered typical of advanced age. Most cases of NSCLC are diagnosed in the advanced or locally advanced stage. It has been shown that combined chemo-radiotherapy is more efficient than either chemotherapy alone or radiation alone, for the therapeutic management of localized unresectable NSCLC. However, chemo-radiotherapy, even if given with sequential approach, in clinical practice can be contraindicated in elderly patients. In fact, this patient population often present at diagnosis with cardiovascular and/or pulmonary comorbidities that increase the risk of severe side effects from chemo-radiotherapy. The present review aims at focusing the currently available evidences on the treatment of elderly patients affected by locally advanced NSCLC and at giving future perspectives on this topic.

RECENT FINDINGS

Very few specific prospective data are available on the treatment of locally advanced NSCLC in the elderly. Some phase II studies suggest that low-dose chemotherapy given concurrently with radiotherapy could be safely administered to this patient population. Retrospective analyses on full-dose sequential and concurrent chemo-radiation are to be considered globally ambiguous and at risk of selection bias.

SUMMARY

Only specifically designed prospective studies will elucidate the real role and feasibility of combined chemo-radiotherapy in the treatment of locally advanced NSCLC in the elderly. Future perspectives on this topic include the evaluation of alternative schedules of chemo-radiotherapy, innovative radiation techniques more suitable to elderly patients, and the introduction of new, well-tolerated, molecularly targeted agents combined with standard treatments.