Optimizing First-Line Chemotherapy in Metastatic Pancreatic Cancer: Efficacy of FOLFIRINOX versus Nab-Paclitaxel Plus Gemcitabine

Pancreatic cancer (PC) is one of the most lethal tumors in Europe with an overall 5-year survival rate of 5%. Since 1992, gemcitabine (Gem) has been the treatment of choice for metastatic disease with significant improvement in median overall survival (OS) compared to fluorouracil. A good performance status (PS) at diagnosis appears to be a strong predictive factor for better survival. Overall, 50% of PC are metastatic or locally advanced at diagnosis, and more than 70% of the resected patients will experience a recurrence, with a median OS ranging from 4 to 10 months (mos). FOLFIRINOX (5-fluorouracil, leucovorin, irinotecan, and oxaliplatin) and Nab-paclitaxel (Nab-p) plus Gem have recently increased survival of patients with metastatic PC, over Gem. Treatment with FOLFIRINOX is generally considered more effective with respect to the doublet, with toxicity concerns, FOLFIRINOX achieves an overall response rate (ORR) of 31.6%, while for Nab-p plus Gem ORR is 23%; however, FOLFIRINOX was associated with higher rates of grade 3 and higher adverse events. Although the international guidelines indicate that both regimens can be used as first-line therapy for patients with metastatic PC, FOLFIRINOX is the most widely used; Nab-p plus Gem is more frequently used in patients with lower PS. In this review, we critically analyze these two regimens to give a pragmatic guide to treatment options.

Pulmonary Toxicities from Conventional Chemotherapy

Despite significant recent progress in precision medicine and immunotherapy, conventional chemotherapy remains the cornerstone of the treatment of most cancers. Chemotherapy-induced lung toxicity represents a serious diagnostic challenge for health care providers and requires careful consideration because it is a diagnosis of exclusion with significant impact on therapeutic decisions. This review aims to provide clinicians with a valuable guide in assessing their patients with possible chemotherapy-induced lung toxicity.

Roles of aldo-keto reductases 1B10 and 1C3 and ATP-binding cassette transporter in docetaxel tolerance

Docetaxel (DTX) is widely used for treatment of inveterate lung and prostate cancers, but its continuous administration elicits the hyposensitivity. Here, we established the DTX-resistant variants of human lung cancer A549 and androgen-independent prostate cancer Du145 cells and found that the resistance development provoked aberrant up-regulations of aldo-keto reductase (AKR) 1B10 and AKR1C3 in A549 and Du145 cells, respectively. In addition, the sensitivity to the DTX toxicity was significantly decreased and increased by overexpression and knockdown of the two AKR isoforms, respectively. Furthermore, the resistant cells exhibited a decreased level of reactive 4-hydroxy-2-nonenal formed during DTX treatment, and the decrease was alleviated by adding the AKR inhibitors, inferring that the two AKRs confer the chemoresistance through elevating the antioxidant properties. The development of DTX resistance was also associated with enhanced expression of an ATP-binding cassette (ABC) transporter ABCB1 among the ABC transporter isoforms. The combined treatment with inhibitors of the two AKRs and ABCB1 additively sensitized the resistant cells to DTX. Intriguingly, the AKR1B10 inhibitor also suppressed the lung cancer cross-resistance against cisplatin. The results suggest that combined treatment with AKRs (1B10 and 1C3) and ABCB1 inhibitors exerts overcoming effect against the cancer resistance to DTX and cisplatin, and can be used as the adjuvant therapy.

Natural Products as a Vital Source for the Discovery of Cancer Chemotherapeutic and Chemopreventive Agents

Throughout history, natural products have played a dominant role in the treatment of human ailments. For example, the legendary discovery of penicillin transformed global existence. Presently, natural products comprise a large portion of current-day pharmaceutical agents, most notably in the area of cancer therapy. Examples include Taxol, vinblastine, and camptothecin. These structurally unique agents function by novel mechanisms of action; isolation from natural sources is the only plausible method that could have led to their discovery. In addition to terrestrial plants as sources for starting materials, the marine environment (e.g., ecteinascidin 743, halichondrin B, and dolastatins), microbes (e.g., bleomycin, doxorubicin, and staurosporin), and slime molds (e.g., epothilone B) have yielded remarkable cancer chemotherapeutic agents. Irrespective of these advances, cancer remains a leading cause of death worldwide. Undoubtedly, the prevention of human cancer is highly preferable to treatment. Cancer chemoprevention, the use of vaccines or pharmaceutical agents to inhibit, retard, or reverse the process of carcinogenesis, is another important approach for easing this formidable public health burden. Similar to cancer chemotherapeutic agents, natural products play an important role in this field. There are many examples, including dietary phytochemicals such as sulforaphane and phenethyl isothiocyanate (cruciferous vegetables) and resveratrol (grapes and grape products). Overall, natural product research is a powerful approach for discovering biologically active compounds with unique structures and mechanisms of action. Given the unfathomable diversity of nature, it is reasonable to suggest that chemical leads can be generated that are capable of interacting with most or possibly all therapeutic targets.

Encapsulated paclitaxel nanoparticles exhibit enhanced anti-tumor efficacy in A549 non-small lung cancer cells

In the present study, paclitaxel (PTX) were encapsulated with polyethylene glycol (PEG)-polylactide (PLA)/D-α tocopheryl polyethylene glycol 1000 succinate (TPGS) (PEG-PLA/TPGS) and the enhanced anti-tumor activity of this PTX mixed micelles (PTX-MM) was evaluated in lung cancer cells. The PTX-MM prepared by a solvent evaporation method was demonstrated to have high drug-loading efficiency (23.2%), high encapsulation efficiency (76.4%), and small size (59 nm). In vitro release assay showed the slow release behavior of PTX-MM, suggesting the good stability of the PTX-MM essential for long circulation time. In vitro kinetics assay demonstrated that PTX-MM could promote absorption and increase relative bioavailability. The anti-cancer efficiency of PTX-MM was also examined by both in vitro and in vivo studies. PTX-MM exhibits obvious cytotoxicity against lung cancer cells with much lower IC50 value when compared with commercial formulated PTX or PTX + TPGS. The xenograft tumor model studies on nude mice indicated that PTX-MM inhibits tumor growth more effectively than other formulations. It was also found that most of mixed micelles were integral in tumor site to exhibit anti-cancer activity. Our results suggested that the use of PTX-MM as an anti-cancer drug may be an effective approach to treat lung cancer.

Triptolide reverses the Taxol resistance of lung adenocarcinoma by inhibiting the NF-κB signaling pathway and the expression of NF-κB-regulated drug-resistant genes

Paclitaxel (or Taxol®) is a first-line chemotherapeutic drug for the treatment of non-small cell lung cancer; however, resistance to the drug is an important factor, which influences the outcome of chemotherapy. The present study aimed to investigate the role of triptolide (TPL) in reversing Taxol‑resistant human lung adenocarcinoma and to elucidate the underlying molecular mechanism of resistance reversal mediated by TPL. It was hypothesized that this experimental approach would assist in solving the problem of chemotherapeutic resistance in non‑small cell lung cancer, thereby improving the clinical outcomes. The human Taxol‑resistant lung adenocarcinoma cell line, A549/Taxol, was established. The resistance index of the cell line was calculated, according to the half maximal inhibitory concentration (IC50) of A549/Taxol IC50 of A549, to be 51.87. The levels of apoptosis and the cell cycle in the A549/Taxol cell line were assessed to confirm the effects of TPL at three different concentrations (0.03, 0.3 and 3 µmol/l) and treatment durations (2, 4, 6 and 12 h) by flow cytometric analysis, and the inhibition of the NF‑κB signaling pathway and the expression of NF‑κB‑regulated drug‑resistant proteins were determined by immunofluorescence and western blotting, respectively. The administration of TPL promoted cell apoptosis in the A549/Taxol lung adenocarcinoma Taxol‑resistant cell line and also promoted cell cycle regulation. The drug was also able to elicit a reversal of the drug resistance. TPL inhibited the nuclear factor‑κB (NF‑κB) signaling pathway and the expression of NF‑κB‑regulated drug‑resistant genes, including those for FLICE‑like inhibitory protein, X‑linked inhibitor of apoptosis protein, Bcl‑2, Bcl‑xL and cyclo‑oxygenase‑2. TPL exerted a marked drug‑resistance‑reversal effect on human lung adenocarcinoma Taxol resistance, and the effect was revealed to be dose‑ and time‑dependent. In conclusion, TPL exerted its role in the process of resistance reversal by inhibiting the NF‑κB signaling pathway, and the transcription and expression of NF-κB-regulated drug-resistant genes.

Acute Respiratory Distress Syndrome after Treatment of Metastatic Prostate Cancer with Taxotere: A Case Report and Literature Review

Prostate cancer is the most common cancer in men. Docetaxel is a common chemotherapeutic agent that has proven its efficacy in the treatment of patients with both castration sensitive and resistant metastatic prostate cancer. We report a case of acute respiratory distress syndrome (ARDS) in a patient with metastatic prostate cancer treated with docetaxel (Taxotere). ARDS is very rare but life threatening complication of docetaxel which requires aggressive supportive care and close monitoring. Better awareness and prompt diagnosis of this treatment related ARDS will improve the effectiveness and outcome of its management.

MicroRNA-7 sensitizes non-small cell lung cancer cells to paclitaxel

Paclitaxel (PTX) is the front-line chemotherapeutic agent against human non-small cell lung cancer (NSCLC). However, its therapeutic efficacy is restricted by the increasing frequency of chemotherapeutic resistance in NSCLC. Accumulating evidence has shown the potential role of microRNAs (miRNAs) in the chemotherapeutic sensitivity of cancer cells. Previously it was reported that microRNA-7 (miR-7) acts as an important tumor suppressor in NSCLC. Therefore, the present study was conducted to determine the regulatory role of miR-7 in PTX chemotherapy for NSCLC. Four NSCLC cell lines were used to analyze the correlation of the PTX-sensitivity and endogenoaus miR-7 expression. miR-7 expression was up- and downregulated using miR-7 mimics and inhibitors respectively, and the role of miR-7 in sensitizing NSCLC cells to PTX was assessed by cell viability and apoptosis assays. The molecular mechanism of PTX sensitivity was determined by quantitative polymerase chain reaction and western blotting. It was found that the sensitivity of NSCLC cells to PTX was dependent on endogenous miR-7. Upregulation of miR-7 enhanced the PTX-sensitivity of NSCLC cells by suppressing cell proliferation and promoting cell apoptosis, while the inhibition of miR-7 abrogated the antiproliferative proapoptotic effects of PTX. Pretreatment of miR-7 mimics enhanced the PTX-mediated downregulation of epidermal growth factor receptor (EGFR) in NSCLC cells. These results have identified miR-7 as a potential EGFR-targeting sensitizer in PTX therapy. These data may facilitate the development of novel chemotherapeutic approaches for NSCLC.

Use of epothilone B (patupilone) in refractory lymphoma and advanced solid tumors in dogs

BACKGROUND

The epothilones are microtubule-stabilizing agents with promising antitumor effect in refractory and metastatic tumors in humans. The toxicity profile is considered more favorable than in taxanes. The safety of epothilone B (patupilone) has not been evaluated in tumor-bearing dogs.

OBJECTIVES

To evaluate the inhibition of proliferation in canine tumor cells after patupilone treatment. To assess toxicity profile and maximally tolerated dose of patupilone in dogs with refractory tumors.

ANIMALS

Twenty client-owned dogs with various malignancies.

METHODS

Prospective clinical study. The inhibition of proliferation was assessed with a proliferation assay in vitro in canine hemangiosarcoma and lymphoma cell lines. Dogs received patupilone IV once a week for 2 treatments (= 1 treatment cycle). Dose was escalated with 3 dogs per cohort and 20% increments. Adverse effects were graded according to the VCOG-CTCAE v1.0.

RESULTS

Both canine cell lines were sensitive to patupilone with approximately 50% decrease in proliferative activity at 0.2-1 nM. In vivo, dose-limiting adverse effects occurred at 3.3 mg/m(2); main adverse effects were diarrhea, anorexia, vomiting, and nausea. Neither neutropenia nor peripheral neuropathy was observed. Maximally tolerated dose for 2 patupilone administrations once weekly IV is 2.76 mg/m(2). Three per 11 dogs receiving more than 1 treatment cycle showed partial remission in the short period of observation.

CONCLUSIONS AND CLINICAL IMPORTANCE

Canine tumor cells show inhibition of proliferation to patupilone in vitro. Clinically, a dose of 2.76 mg/m(2) IV is well tolerated in dogs with spontaneously occurring tumors.

Microtubule stabilising agents and ionising radiation: multiple exploitable mechanisms for combined treatment

Combined radiochemotherapy treatment modalities are in use for many indications and therefore of high interest. Even though a combined modality in clinical use is often driven by pragmatic aspects, mechanistic preclinical-based concepts of interaction are of importance in order to translate and implement an optimal combination and scheduling of two modalities into the clinics. The use of microtubule stabilising agents is a promising strategy for anti-cancer therapy as a part of combined treatment modality with ionising radiation. Traditionally, microtubule targeting agents are classified as cytotoxic chemotherapeutics and are mostly used in a maximally tolerated dose regimen. Apart from direct cytotoxicity and similar to mechanisms of molecular targeting agents, microtubule stabilising agents interfere with multiple cellular processes, which can be exploited as part of combined treatment modalities. Recent preclinical investigations on the combination of ionising radiation and microtubule stabilising agents reveal new mechanistic interactions on the cellular and tumour level and elucidate the supra-additive tumour response observed particularly in vivo. The major focus on the mechanism of interaction was primarily based on radiosensitisation due to cell cycle arrest in the most radiosensitive G2/M-phase of the cell cycle. However, other mechanisms of interaction such as reoxygenation and direct as well as indirect endothelial damage have also been identified. In this review we summarise and allocate additive and synergistic effects induced by the combined treatment of clinically relevant microtubule stabilising agents and ionising radiation along a described radiobiological framework encompassing distinct mechanisms relevant for exploiting the combination of drugs and ionising radiation.

Folate-targeted polymeric nanoparticle formulation of docetaxel is an effective molecularly targeted radiosensitizer with efficacy dependent on the timing of radiotherapy

Nanoparticle (NP) chemotherapeutics hold great potential as radiosensitizers. Their unique properties, such as preferential accumulation in tumors and their ability to target tumors through molecular targeting ligands, are ideally suited for radiosensitization. We aimed to develop a molecularly targeted nanoparticle formulation of docetaxel (Dtxl) and evaluate its property as a radiosensitizer. Using a biodegradable and biocompatible lipid-polymer NP platform and folate as a molecular targeting ligand, we engineered a folate-targeted nanoparticle (FT-NP) formulation of Dtxl. These NPs have sizes of 72 ± 4 nm and surface charges of -42 ± 8 mV. Using folate receptor overexpressing KB cells and folate receptor low HTB-43 cells, we showed folate-mediated intracellular uptake of NPs. In vitro radiosensitization studies initially showed FT-NP is less effective than Dtxl as a radiosensitizer. However, the radiosensitization efficacy is dependent on the timing of radiotherapy. In vitro radiosensitization conducted with irradiation given at the optimal time (24 h) showed FT-NP Dtxl is as effective as Dtxl. When FT-NP Dtxl is compared to Dtxl and nontargeted nanoparticle (NT-NP) Dtxl in vivo, FT-NP was found to be significantly more effective than Dtxl or NT-NP Dtxl as a radiosensitizer. We also confirmed that radiosensitization is dependent on timing of irradiation in vivo. In summary, FT-NP Dtxl is an effective radiosensitizer in folate-receptor overexpressing tumor cells. Time of irradiation is critical in achieving maximal efficacy with this nanoparticle platform. To the best of our knowledge, our report is the first to demonstrate the potential of molecularly targeted NPs as a promising new class of radiosensitizers.

Synergistic interactions between peloruside A and other microtubule-stabilizing and destabilizing agents in cultured human ovarian carcinoma cells and murine T cells

PURPOSE

Microtubule-stabilizing agents are an important class of anticancer compounds. Peloruside A and laulimalide bind to a different site on the microtubule to taxoid site drugs such as paclitaxel (Taxol(®)), docetaxel (Taxotere(®)), ixabepilone (Ixempra(®)), the epothilones, and discodermolide. The purpose of this study was to examine the synergistic interactions of these drugs when given in combination in relation to the differences in their binding sites on the microtubule.

METHODS

Human ovarian carcinoma cells (1A9 cells) and murine T cells were treated with different combinations of microtubule-stabilizing or destabilizing agents. The compounds were given individually and in combination, and the antiproliferative activity was assessed to calculate a combination index (CI) from the equation: CI = D(1)/Dx(1) + D(2)/Dx(2) in which D(1) and D(2) are the concentrations of drug 1 and drug 2 that when given together give the same response as drug 1 and 2 alone (Dx(1) and Dx(2)). Thus, a CI value of less than 1.0 indicates a synergistic effect between the two drugs in which the response to the two drugs given together is greater than the additive response of the two drugs if given on their own.

RESULTS

As anticipated from previous in vitro studies, peloruside A and laulimalide did not synergize with each other. They also failed to synergize with the microtubule-destabilizing agents vinblastine and 2-methoxyestradiol. Peloruside A and laulimalide did, however, synergize with the epothilones, as had been previously shown, but not with docetaxel or discodermolide.

CONCLUSIONS

Combining two microtubule-targeting agents with different binding sites does not guarantee a synergistic interaction in cells, and additional factors are likely to be involved. This study highlights the importance of preclinical testing of actual combinations of drugs before proceeding into clinical trials.

Novel self-associating poly(ethylene oxide)-b-poly(epsilon-caprolactone) based drug conjugates and nano-containers for paclitaxel delivery

Poly(ethylene oxide)-block-poly(epsilon-caprolactone) (PEO-b-PCL) copolymers bearing paclitaxel (PTX) side groups on PCL (PEO-b-P(CL-PTX) were synthesized and assembled to particles of 123 nm average diameter. At 20% (w/w) PTX to polymer conjugation, PEO-b-P(CL-PTX) demonstrated only 5.0 and 6.7% PTX release after 72 h incubation at pH 7.4 and 5.0, respectively, but revealed signs of chain cleavage at pH 5.0. The cytotoxicity of PEO-b-P(CL-PTX) against MDA-MB-435 cancer cells increased as incubation time was raised from 72 to 96 h (IC(50) of 680 and 475 ng/mL, respectively), but it was still significantly lower than the cytotoxicity of free PTX (IC(50) of 3.5 ng/mL at 72 h). In further studies, micelles of PEO-b-PCL and those bearing benzyl or PTX on PCL were used for physical encapsulation of PTX, where maximum level of loading was achieved by PEO-b-P(CL-PTX) (2.22%, w/w). The release of PTX from this carrier was rapid; however. The in vitro cytotoxicity of physically loaded PTX was independent of carrier and similar to that of free PTX. This was attributed to the low concentration of polymers which fell below their critical micellar concentration in the cytotoxicity study. The results point to the potential of chemically tailored PEO-b-PCL for optimum PTX solubilization and delivery.

The use of nanoparticle-mediated targeted gene silencing and drug delivery to overcome tumor drug resistance

Overexpression of drug efflux transporters such as P-glycoprotein (P-gp) enables cancer cells to develop resistance to multiple anticancer drugs. Functional inhibitors of P-gp have shown promising efficacy in early clinical trials, but their long-term safety is yet to be established. A novel approach to overcome drug resistance is to use siRNA-mediated RNA interference to silence the expression of the efflux transporter. Because P-gp plays an important role in the physiological regulation of endogenous and xenobiotic compounds in the body, it is important to deliver P-gp targeted siRNA and anticancer drug specifically to tumor cells. Further, for optimal synergy, both the drug and siRNA may need to be temporally colocalized in the tumor cells. In the current study, we investigated the effectiveness of simultaneous and targeted delivery of anticancer drug, paclitaxel, along with P-gp targeted siRNA, using poly(D,L-lactide-co-glycolide) nanoparticles to overcome tumor drug resistance. Nanoparticles were surface functionalized with biotin for active tumor targeting. Dual agent nanoparticles encapsulating the combination of paclitaxel and P-gp targeted siRNA showed significantly higher cytotoxicity in vitro than nanoparticles loaded with paclitaxel alone. Enhanced therapeutic efficacy of dual agent nanoparticles could be correlated with effective silencing of the MDR1 gene that encodes for P-gp and with increased accumulation of paclitaxel in drug-resistant tumor cells. In vivo studies in a mouse model of drug-resistant tumor demonstrated significantly greater inhibition of tumor growth following treatment with biotin-functionalized nanoparticles encapsulating both paclitaxel and P-gp targeted siRNA at a paclitaxel dose that was ineffective in the absence of gene silencing. These results suggest that that the combination of P-gp gene silencing and cytotoxic drug delivery using targeted nanoparticles can overcome tumor drug resistance.