A Phase I/II Study of Exisulind in Combination with Docetaxel/Carboplatin in Patients with Metastatic Non–Small-Cell Lung Cancer

Phosphodiesterase type 5 and cancers: progress and challenges

Cancers are an extraordinarily heterogeneous collection of diseases with distinct genetic profiles and biological features that directly influence response patterns to various treatment strategies as well as clinical outcomes. Nevertheless, our growing understanding of cancer cell biology and tumor progression is gradually leading towards rational, tailored medical treatments designed to destroy cancer cells by exploiting the unique cellular pathways that distinguish them from normal healthy counterparts. Recently, inhibition of the activity of phosphodiesterase type 5 (PDE5) is emerging as a promising approach to restore normal intracellular cyclic guanosine monophosphate (cGMP) signalling, and thereby resulting into the activation of various downstream molecules to inhibit proliferation, motility and invasion of certain cancer cells. In this review, we present an overview of the experimental and clinical evidences highlighting the role of PDE5 in the pathogenesis and prevention of various malignancies. Current data are still not sufficient to draw conclusive statements for cancer patient management, but could provide further rational for testing PDE5-targeting drugs as anticancer agents in clinical settings.

Exisulind in the treatment of prostate cancer

Prostate cancer represents the most common noncutaneous malignancy in men. With the widespread use of prostate-specific antigen screening, as many as one in six men in the USA will be diagnosed with prostate cancer. Significant healthcare resources are currently devoted to the treatment of this disease, specifically aimed at improving the side effects of successful treatment. Surgery or radiation therapy provides the best chance of cure from this disease. However, as many as 50% of patients treated with curative intent will develop a recurrence 10-15 years following treatment. Hormonal ablation via medical or surgical castration provides disease control, but is associated with significant hot flushes, loss of libido and impotence. Selective, apoptotic antineoplastic drugs, such as exisulind, may provide an alternative method to treating or preventing prostate cancer. This drug profile reviews the evidence for the use of exisulind in the treatment of prostate cancer.

A phase I study of OSI-461 in combination with mitoxantrone in patients with advanced solid tumors potentially responsive to mitoxantrone

Purpose

To find the maximum tolerated dose (MTD) of OSI-461 in combination with mitoxantrone in patients with advanced solid tumors.

Methods

This was a Phase I study using cohort dose escalation of OSI-461 dosed orally twice daily in combination with mitoxantrone 12 mg/m² given on Day 1 of each 21-day cycle.

Results

OSI-461 dose was escalated to 1,000 mg po bid. One patient experienced a dose-limiting toxicity (DLT). Three patients discontinued the study due to adverse events (AE). Two patients (10%) had a partial response, and ten patients (50%) had stable disease as best response.

Conclusion

The combination of OSI-461 and mitoxantrone was well tolerated. Dose escalation was stopped because of toxicities in a concurrent Phase I trial. The response rate seen in patients with prostate cancer was comparable to response rates seen in trials of mitoxantrone and prednisone alone, and further studies of the combination of OSI-461 and mitoxantrone were not pursued.

Phase I/II study of vinorelbine and exisulind as first-line treatment of advanced non-small cell lung cancer in patients at least 70 years old: a wisconsin oncology network study

INTRODUCTION

Exisulind is an apoptotic agent with preclinical activity in non-small cell lung cancer (NSCLC). Vinorelbine is safe and effective in older patients with advanced NSCLC. We assessed these agents together as palliative treatment for older patients with advanced NSCLC.

METHODS

Chemotherapy-naive patients >/=70-years-old with stage IIIB-IV NSCLC and a performance status (PS) </=2 were eligible. Primary endpoints were the maximum tolerated dose (phase I) and time-to-progression (phase II) of oral exisulind with 25 mg/m/wk of intravenous vinorelbine on a 28-day cycle. Patients with clinical benefit after 6 cycles of this combination received exisulind alone.

RESULTS

Fourteen phase I patients (median PS 1; median age 78 years) were enrolled. Dose-limiting toxicities included grade 3 constipation (one patient), grade 3 febrile neutropenia (one patient) and grade 3 diarrhea (one patient). The maximum tolerated dose of oral exisulind with 25 mg/m/wk of intravenous vinorelbine was 125 mg twice daily. Thirty phase II patients (median PS 1; median age 78 years) were enrolled. Grade >/=3 neutropenia occurred in 14/30 patients. Two patients experienced neutropenic fever. There were no complete responses, one partial response and 12 patients with stable disease as their best response. The objective response rate was 4.0% (95% CI: 0.1-20.4%). Phase II median time-to-progression was 4.7 months (95% CI: 3.1-9.3 months) and median OS was 9.6 months (95% CI: 6.6-19.1 months).

CONCLUSIONS

This combination is safe, seems to have activity in the elderly with advanced NSCLC and a PS </=2, and warrants further investigation.

A dose-ranging study of the pharmacokinetics and pharmacodynamics of the selective apoptotic antineoplastic drug (SAAND), OSI-461, in patients with advanced cancer, in the fasted and fed state

PURPOSE

To evaluate the safety, pharmacokinetics and determine the recommended dose of the selective apoptotic antineoplastic drug, OSI-461 administered on a twice-daily regimen to patients with advanced solid malignancies.

METHODS

In this phase I trial, 33 patients were treated with OSI-461 doses ranging from 400 to 1,200 mg given twice daily in 4-week cycles. Pharmacokinetic studies were performed to characterize the plasma disposition of OSI-461 and the effect of food intake on OSI-461 absorption. Secondary biomarker studies were performed to assess the biologic activity of OSI-461 including the measurement of pGSK-3beta, a PKG substrate, and pharmacogenetic studies to identify polymorphisms of CYP3A that influence drug metabolism and of ABCG2, involved in drug resistance.

RESULTS

Thirty-three patients were treated with 86 courses of OSI-461. The dose-limiting toxicities were grade 3 abdominal pain, found in one patient at the 1,000 mg BID fed dose level and all patients at the 1,200 mg BID fed dose level. There was also one episode each of grade 3 fatigue and grade 3 constipation at the 1,000 and 1,200 mg BID fed dose levels, respectively. Other common toxicities included mild to moderate fatigue, nausea, anorexia and mild elevation in bilirubin. Pharmacokinetic studies of OSI-461 revealed approximately a twofold increase in AUC(0-24) when OSI-461 was administered with food. An increase in pGSK-3beta post-dose was seen in the majority of patients and was greater at higher dose levels. No patients exhibited CYP3A4 polymorphisms, while 100% of patients were found to have the CYP3A5*3/CYP3A5*3 polymorphism. Two known polymorphisms of the ABCG2 gene, G34 --> A34 and C421 --> A421, occurred at frequencies of 11.76 and 29%, respectively.

CONCLUSIONS

Toxicity and pharmacodynamic data show that the recommended oral dose of OSI-461 is 800 mg twice daily administered with food. The drug appears to be well-tolerated, and overall bioavailability appears to be markedly increased when the drug is administered with food. These results support further disease-directed evaluations of OSI-461 at a dose of 800 mg BID in combination with other chemotherapeutic agents.

Apoptosis: a relevant tool for anticancer therapy

Apoptosis is a form of cell death that permits the removal of damaged, senescent or unwanted cells in multicellular organisms, without damage to the cellular microenvironment. Defective apoptosis represents a major causative factor in the development and progression of cancer. The majority of chemotherapeutic agents, as well as radiation, utilize the apoptotic pathway to induce cancer cell death. Resistance to standard chemotherapeutic strategies also seems to be due to alterations in the apoptotic pathway of cancer cells. Recent knowledge on apoptosis has provided the basis for novel targeted therapies that exploit apoptosis to treat cancer. These new target include those acting in the extrinsic/intrinsic pathway, proteins that control the apoptosis machinery such as the p53 and proteosome pathway. Most of these forms of therapy are still in preclinical development because of their low specifity and susceptibility to drug resistance, but several of them have shown promising results. In particular, this review specifically aims at providing an update of certain molecular players that are already in use in order to target apoptosis (such as bortezomib) or which are still being clinically evaluated (such ONYX-015, survivin and exisulind/aptosyn) or which, following preclinical studies, might have the necessary requirements for becoming part of the anticancer drug programs (such as TRAIL/Apo2L, apoptin/VP3).

Combined effects of sulindac and suberoylanilide hydroxamic acid on apoptosis induction in human lung cancer cells

Histone deacetylase (HDAC) inhibitors represent a promising group of anticancer agents. Treatment of cancer cells with HDAC blockers, such as suberoylanilide hydroxamic acid (SAHA), leads to the activation of apoptosis-promoting genes. To enhance proapoptotic efficiency, SAHA has been used in conjunction with radiation, kinase inhibitors, and cytotoxic drugs. In the present study, we show that at the suboptimal dose of 250 muM, sulindac [2-[6-fluoro-2-methyl-3-[(4-methylsulfinylphenyl)methylidene]inden-1-yl]-acetic acid] significantly enhances SAHA-induced growth suppression and apoptosis of A549 human non-small cell lung cancer cells, primarily via enhanced collapse of the mitochondrial membrane potential, release of cytochrome c, and caspase activation. Furthermore, sulindac/SAHA cotreatment induced marked down-regulation of survivin at both the mRNA and protein levels and stimulated the production of reactive oxygen species (ROS), which were blocked by the antioxidant N-acetyl-l-cysteine. Overexpression of survivin was associated with reduced sulindac/SAHA-induced apoptosis of A549 cells, whereas suppression of survivin levels with antisense oligonucleotides or small interfering RNA further sensitized cells to sulindac/SAHA-induced cell death. Our results collectively demonstrate that sulindac/SAHA-induced apoptosis is mediated by ROS-dependent down-regulation of survivin in lung cancer cells.

Phase I/II study of gemcitabine and exisulind as second-line therapy in patients with advanced non-small cell lung cancer

BACKGROUND

The study was designed to evaluate the safety and efficacy of exisulind, a selective apoptotic antineoplastic drug, in combination with gemcitabine as second-line therapy in patients with progressing advanced non-small cell lung cancer.

METHODS

Patients whose disease progressed more than 3 months from completion of first-line chemotherapy were eligible for this phase I/II trial. Primary end points were maximally tolerated dose and time to progression. Patients in the phase I portion of the study were treated with gemcitabine (1250 mg/m) in combination with three escalated dose levels of exisulind. Treatment involved six cycles of gemcitabine and exisulind followed by exisulind maintenance. The study was subsequently expanded to phase II.

RESULTS

Thirty-nine patients (15 in phase I and 24 in phase II) were treated. The regimen was well tolerated with grade 3 fatigue and grade 3 constipation being dose-limiting toxicities. The maximally tolerated dose was not reached. Dose level 3 of exisulind (250 mg twice daily) in combination with gemcitabine was used for phase II. The overall response rates were 7% (phase I), 17% (phase II), and 13% (all). Median time to progression and median and 1-year survival, respectively, were 3.7 and 9.7 months and 33% (phase I); 4.3 and 9.4 months and 41% (phase II); and 4.1 and 9.4 months and 39% (all).

CONCLUSION

Although the study met its primary end point of improving time to progression (more than 4.1 months in phase II), we did not observe a clear survival advantage and thus do not plan to further investigate this schedule of gemcitabine and exisulind.

Alpha-tocopheryl succinate sensitizes human colon cancer cells to exisulind-induced apoptosis

Sulindac sulfone (also known as exisulind) and its chemical derivatives are promising anticancer agents capable of inducing apoptosis in a variety of malignant cell types with minimal toxicity to normal cells. Here, we tested the ability of alpha-tocopheryl succinate (TOS), another promising anticancer agent, to sensitize colon cancer cells to exisulind-induced apoptosis. We found that sub-apoptotic doses of TOS greatly enhanced exisulind-induced growth suppression and apoptosis in the HCT116, LoVo and SNU-C4 human colon cancer cell lines. Our results revealed that this was accounted for primarily by an augmented cleavage of poly(ADP-ribose) polymerase (PARP) and enhanced activation of caspase-8, -9 and -3. Pretreatment with z-VAD-FMK (a pan-caspase inhibitor), z-IETD-FMK (a caspase-8 inhibitor) or z-LEHD-FMK (a caspase-9 inhibitor) blocked TOS and exisulind cotreatment-induced PARP cleavage and apoptosis. Furthermore, TOS/exisulind cotreatment induced JNK phosphorylation, while pretreatment with SP600151 (a JNK inhibitor) partially blocked cotreatment-induced caspase-dependent PARP cleavage and apoptosis. Taken together, these findings indicate that TOS sensitizes human colon cancer cells to exisulind-induced apoptosis. Apoptotic synergy induced by exisulind plus TOS seems likely to be mediated through a mechanism involving activation of caspases and JNK.

A phase I clinical and pharmacokinetic study of the multi-drug resistance protein-1 (MRP-1) inhibitor sulindac, in combination with epirubicin in patients with advanced cancer

PURPOSE

Multi-drug resistance mediated by ATP-binding cassette trans-membrane protein pumps is an important cause of cancer treatment failure. Sulindac has been shown to be a competitive substrate for the clinically important resistance protein, multi-drug resistance protein-1 (MRP-1), and thus might enhance the anti-cancer activity of substrate chemotherapeutic agents, e.g. anthracyclines.

METHODS

We conducted a dose-escalating, single arm, prospective, open label, non-randomised phase I trial of epirubicin (75 mg/m(2)) in combination with escalating oral doses of sulindac (0-800 mg) in patients with advanced cancer to identify an appropriate dose of sulindac to use in future resistance studies. Anthracycline and sulindac pharmacokinetics were studied in cycles 1 and 3.

RESULTS

Seventeen patients (8 breast, 3 lung, 2 bowel, 1 melanoma, 1 renal, 1 ovarian and 1 of unknown primary origin, 16/17 having had prior chemotherapy) were enrolled. Eight patients received a full six cycles of treatment; 14 patients received three or more cycles. Dose-limiting toxicity was observed in two patients at 800 mg sulindac (1 renal impairment, 1 fatal haemoptysis in a patient with advanced lung cancer), and sulindac 600 mg was deemed to be the maximum tolerated dose. Sulindac had no effect on epirubicin pharmacokinetics. Among 15 patients with evaluable tumour, two partial responses were seen (malignant melanoma and breast cancer). Four others had prolonged stable disease.

CONCLUSION

Epirubicin 75 mg/m(2) and sulindac 600 mg are the recommended doses for phase II studies for these agents in combination.

Other Compounds and Targets in Non–Small Cell Lung Cancer

It has become increasingly apparent in recent years that a therapeutic plateau has been reached for patients with advanced stage non-small cell lung cancer (NSCLC) treated with conventional cytotoxic agents. As a result, investigators have directed their efforts toward the development of treatments encompassing novel targeted agents. Apoptosis is one of many cellular pathways currently under investigation as a therapeutic target for the treatment of NSCLC. Anti-inflammatory agents, including cyclooxygenase inhibitors, have been shown to inhibit apoptosis and appear promising based on preclinical studies. However, several phase II studies indicate that this therapeutic strategy is unlikely to be successful. In contrast, the proteosome inhibitor bortezomib has shown promise in preliminary studies, and further efforts to elucidate the role this agent may play in the treatment of NSCLC are ongoing. Agonists of the tumor necrosis factor-related, apoptosis-inducing ligand have also entered into early clinical studies in patients with NSCLC. Further studies will be needed to fully clarify how agents targeting the apoptotic pathway can be used in the treatment of NSCLC, but the results of current clinical trials suggest that certain agents may be active.