A Phase I Trial of Pemetrexed Plus Gemcitabine Given Biweekly with B-Vitamin Support in Solid Tumor Malignancies or Advanced Epithelial Ovarian Cancer

Lymphopenia and intratumoral lymphocytic balance in the era of cancer immuno-radiotherapy

INTRODUCTION

The immune response has been recognized as a major tumor-eradication component of radiotherapy.

OBJECTIVE

This review studies, under a clinical perspective, two contrasting effects of radiotherapy, namely immunosuppression and radiovaccination.

MATERIALS AND METHODS

We critically reviewed the available clinical and experimental experience on radiotherapy-induced lymphopenia.

RESULTS

Radiation-induced tumor damage promotes radio-vaccination, enhances cytotoxic immune responses, and potentiates immunotherapy. Nevertheless, radiotherapy induces systemic and intratumoral lymphopenia. The above effects are directly related to radiotherapy fractionation and field size/location, and tumor characteristics.

DISCUSSION

Hypofractionated stereotactic and accelerated irradiation better promotes radio-vaccination and produces less severe lymphopenia. Adopting cytoprotective policies and combining lympho-stimulatory agents or agents blocking regulatory lymphocyte activity are awaited to unmask the radio-vaccination effect, enhancing the efficacy immuno-radiotherapy.

CONCLUSION

Radiation-induced lymphopenia and immunosuppression are important issues that should be considered in the design of immuno-radiotherapy clinical trials.

Human Thymidylate Synthase Inhibitors Halting Ovarian Cancer Growth

Human thymidylate synthase (hTS) has an important role in DNA biosynthesis, thus it is essential for cell survival. TS is involved in the folate pathways, specifically in the de novo pyrimidine biosynthesis. Structure and functions are intimately correlated, account for cellular activity and, in a broader view, with in vivo mechanisms. hTS is a target for anticancer agents, some of which are clinical drugs. The understanding of the detailed mechanism of TS inhibition by currently used drugs and of the interaction with the mechanism of action of other anticancer agents can suggest new perspective of TS inhibition able to improve the anticancer effect and to overcome drug resistance. TS-targeting drugs in therapy today are inhibitors that bind at the active site and that mostly resemble the substrates. Nonsubstrate analogs offer an opportunity for allosteric binding and novel mode of inhibition in the cancer cells. This chapter illustrates the relationship among the large number of hTS actions at molecular and clinical levels, its role as a target for ovarian cancer therapy, in particular in cases of overexpression of hTS and other folate proteins such as those induced by platinum drug treatments, and address the potential combination of TS inhibitors with other suitable anticancer agents.

The role of pemetrexed in recurrent epithelial ovarian cancer: A scoping review

Ovarian cancer is the leading cause of mortality among gynecologic malignancies, with most cases diagnosed at an advanced stage. Despite an initial response, most develop a recurrence and subsequent resistance to standard therapies. Pemetrexed (AlimtaTM) is a new generation multi-targeted antifolate initially approved for the treatment of malignant pleural mesothelioma. In recent years, it has shown promise in the treatment of recurrent epithelial ovarian cancer. In this review, we outline the current literature and discuss the future of pemetrexed in the setting of recurrent epithelial ovarian cancer.

Inside the biochemical pathways of thymidylate synthase perturbed by anticancer drugs: Novel strategies to overcome cancer chemoresistance

Our current understanding of the mechanisms of action of antitumor agents and the precise mechanisms underlying drug resistance is that these two processes are directly linked. Moreover, it is often possible to delineate chemoresistance mechanisms based on the specific mechanism of action of a given anticancer drug. A more holistic approach to the chemoresistance problem suggests that entire metabolic pathways, rather than single enzyme targets may better explain and educate us about the complexity of the cellular responses upon cytotoxic drug administration. Drugs, which target thymidylate synthase and folate-dependent enzymes, represent an important therapeutic arm in the treatment of various human malignancies. However, prolonged patient treatment often provokes drug resistance phenomena that render the chemotherapeutic treatment highly ineffective. Hence, strategies to overcome drug resistance are primarily designed to achieve either enhanced intracellular drug accumulation, to avoid the upregulation of folate-dependent enzymes, and to circumvent the impairment of DNA repair enzymes which are also responsible for cross-resistance to various anticancer drugs. The current clinical practice based on drug combination therapeutic regimens represents the most effective approach to counteract drug resistance. In the current paper, we review the molecular aspects of the activity of TS-targeting drugs and describe how such mechanisms are related to the emergence of clinical drug resistance. We also discuss the current possibilities to overcome drug resistance by using a molecular mechanistic approach based on medicinal chemistry methods focusing on rational structural modifications of novel antitumor agents. This paper also focuses on the importance of the modulation of metabolic pathways upon drug administration, their analysis and the assessment of their putative roles in the networks involved using a meta-analysis approach. The present review describes the main pathways that are modulated by TS-targeting anticancer drugs starting from the description of the normal functioning of the folate metabolic pathway, through the protein modulation occurring upon drug delivery to cultured tumor cells as well as cancer patients, finally describing how the pathways are modulated by drug resistance development. The data collected are then analyzed using network/netwire connecting methods in order to provide a wider view of the pathways involved and of the importance of such information in identifying additional proteins that could serve as novel druggable targets for efficacious cancer therapy.

Pemetrexed for ovarian cancer: a systematic review of the published literature and a consecutive series of patients treated in a nonclinical trial setting

Objective

To gain a better understanding of the role of pemetrexed in ovarian cancer patients, we conducted a systematic review of the published literature and evaluated a consecutive, single-institution series of non-study pemetrexed-treated patients.

Methods/Results

Thirteen published articles met this study's eligibility criteria, providing a total of 376 unique and evaluable ovarian cancer patients. This systematic review demonstrated tumor response rates with pemetrexed-based chemotherapy from 9 to 84%; the agent appeared to be well tolerated. Similarly, 13 consecutive patients with ovarian, fallopian tube, or primary peritoneal cancer were treated with pemetrexed at the Mayo Clinic, Rochester, Minn., USA, from 2004 through 2013. The median number of previous chemotherapy regimens was 4; most patients received single-agent pemetrexed (n = 9). Patients received a median of 2 cycles of pemetrexed-based chemotherapy; 1 patient received 10 cycles (7 months’ worth) with treatment ongoing at the time of this report. The median survival from the start of pemetrexed was 4.8 months (95% confidence interval 1.2, 15 months). Two patients manifested a 50% drop in Ca-125 levels. Again, pemetrexed was relatively well tolerated.

Conclusion

Pemetrexed has antineoplastic activity in patients with ovarian cancer – even among those who have been heavily pretreated – and therefore merits further study.

Photoimmunotherapy and irradiance modulation reduce chemotherapy cycles and toxicity in a murine model for ovarian carcinomatosis: perspective and results

Significant toxicities from multiple cycles of chemotherapy often cause delays or early termination of treatment, leading to poor outcomes in ovarian cancer patients. Complementary modalities that potentiate the efficacy of traditional agents with fewer cycles and less toxicity are needed. Photodynamic therapy is a mechanistically-distinct modality that synergizes with chemo and biologic agents. A combination regimen with a clinically relevant chemotherapy cocktail (cisplatin + paclitaxel) and anti-EGFR targeted photoimmunotherapy (PIT) is evaluated in a murine model for ovarian carcinomatosis. Mice received either 1 or 2 chemotherapy cycles followed by PIT with a chlorine6-Erbitux photoimmunoconjugate and 25 J/cm2 light. PIT + 1 cycle of chemotherapy significantly reduced tumor burden, comparable to multiple chemotherapy cycles. Relative to 1 cycle of chemotherapy, the addition of PIT did not cause significant mouse weight loss, whereas 2 cycles of chemotherapy led to a significant reduction in weight. Irradiance-dependence on PIT efficacy was a function of the conjugation chemistry, providing an additional variable for optimization of PIT outcome.

Phase I trial of intraperitoneal pemetrexed, cisplatin, and paclitaxel in optimally debulked ovarian cancer

PURPOSE

This phase I trial evaluated intraperitoneal (i.p.) pemetrexed, cisplatin, and paclitaxel in optimally debulked ovarian cancer.

EXPERIMENTAL DESIGN

Dose escalation of day 1 i.p. pemetrexed accrued three patients to each of five dose levels (60-1,000 mg/m(2)), along with day 2 i.p. cisplatin (75 mg/m(2)) and day 8 i.p. paclitaxel (60 mg/m(2)). The goals were to determine maximum tolerated dose (MTD), 18-month progression-free survival (PFS), and pharmacokinetics of i.p. pemetrexed.

RESULTS

Cycles, given every 21 days, had an 80% 6-cycle completion rate. There was minimal grade III toxicity in the first 4 dose levels and remarkably an almost complete absence of peripheral neuropathy and alopecia. At the highest dose level, two of three patients experienced ≥ grade III and dose-limiting toxicity (DLT; hematologic, infection, gastrointestinal). There was a pharmacokinetic advantage for i.p. pemetrexed with an intraperitoneal:plasma area under the concentration-time curve ratio of 13-fold. Neither analysis of pharmacokinetic nor homocysteine levels explains the unexpected severity of toxicity in those two patients. On the basis of plasma C(24h) levels, the 42 cycles at ≥ 500 mg/m(2) i.p. pemetrexed without DLT, the MTD appears to be 500 mg/m(2). Median PFS is 30.1 months; 18-month PFS is 78.6% (median follow-up 22.4 months).

CONCLUSIONS

This i.p.-only regimen in front-line ovarian cancer is feasible with PFS in line with recent literature. We suggest phase II trials of this regimen in this population with i.p. pemetrexed at 500 mg/m(2). The favorable toxicity profile at doses <1,000 mg/m(2), which needs to be confirmed, appears to compare well with standard combination i.v./i.p. platinum/taxane chemotherapy in this disease.

Synergistic antitumor activity of gemcitabine and ABT-737 in vitro and in vivo through disrupting the interaction of USP9X and Mcl-1

The Bcl-2 antagonist ABT-737 targets Bcl-2/Bcl-xL, but not Mcl-1, which may confer resistance to this agent in various cancers with high levels of Mcl-1. Here, we showed that the combination of gemcitabine and ABT-737 exhibited synergistic cytotoxicity and induced significant apoptosis in multiple cancer types, including lung, renal, bladder, and prostate cancers. The enhanced apoptosis induced by gemcitabine plus ABT-737 was accompanied by the greater extent of mitochondrial depolarization, caspases-3 activation, and PARP cleavage in 95-D and 5637 cell lines. Importantly, in ABT-737-resistant cancer cells, the interaction between USP9X and Mcl-1, which was increased by ABT-737 treatment, could be disrupted by gemcitabine, thus resulting in enhanced ubiquitination and the subsequent degradation of Mcl-1 and ultimately in the synergism of these two drugs. Moreover, the increased anticancer efficacy of gemcitabine combined with ABT-737 was further validated in a human lung cancer 95-D xenograft model in nude mice. Taken together, our data first showed the synergistic anticancer capabilities achieved by combining gemcitabine and ABT-737 and, second, opened new opportunities to use antiapoptotic Bcl-2 family members, which drive tumor cell resistance in current anticancer therapies, therapeutically.