Antitumor activity in advanced cancer patients with thymic malignancies enrolled in early clinical drug development programs (Phase I trials) at Gustave Roussy

Antitumor effect of dimethyl itaconate on thymic carcinoma by targeting LDHA-mTOR axis

AIMS

Thymic carcinoma is a rare type of cancer without an established standard pharmaceutical treatment. This study investigated the antitumor effect of dimethyl itaconate (DI), a cell-permeable derivative of itaconate, on human thymic carcinoma cell line.

MAIN METHODS

Human thymic carcinoma cell line Ty82 was used to evaluate the effect of DI on cell viability. Western blotting and immunohistochemistry were performed to determine the molecular mechanism of antitumor effects of DI on Ty82.

KEY FINDINGS

DI suppressed cell growth and promoted apoptosis of Ty82. The suppressive effect of DI on Ty82 was mediated by the downregulation of lactate dehydrogenase A (LDHA), and the subsequent decrease in the activity of mechanistic target of rapamycin (mTOR). DI exhibited synergistic antitumor effects with a specific inhibitor of large neutral amino acid transporter 1 (LAT1), an amino acid transporter currently being investigated as a novel target for cancer therapy.

SIGNIFICANCE

Our findings demonstrate that DI is a novel potential strategy for thymic carcinoma treatment.

Thymic malignancies: emerging systemic therapies

PURPOSE OF REVIEW

The management of thymic malignancies is based on multidisciplinary collaboration. Systemic agents may be administered as an exclusive treatment if local treatment is not achievable. Novel and innovative agents are needed. Integrated genomic analyses reported the activation of targetable signaling pathways in thymomas and thymic carcinomas.

RECENT FINDINGS

Phase II trials reported the antitumor activity of phosphatidylinositol 3-kinase/mechanistic target of rapamycin kinase inhibitors, cyclin dependent kinase inhibitors, and antiangiogenic agents in advanced, refractory thymic malignancies. Meanwhile, a major challenge is the use of immune checkpoint inhibitors, given the frequent association of those tumors with autoimmune disorders.

SUMMARY

Although those innovative agents were assessed in phase II trials reporting on variable antitumor efficacy in terms of response and survival, in selected and limited cohorts of patients, a better understanding of systemic treatment sequences in a real-life setting is mandatory to analyze the actual efficacy of each line of treatment one after another, define the best clinical-pathological selection of patients for the administration of chemotherapy, targeted agents, and immunotherapy, and develop individualized decision-making to optimize the survival of patients with advanced thymic malignancies.

Activation of the mTOR/ Akt pathway in thymic epithelial cells derived from thymomas

The pathogenesis of thymic epithelial tumors remains poorly elucidated. The PIK3/Akt/mTOR pathway plays a key role in various cancers; interestingly, several phase I/II studies have reported a positive effect of mTOR inhibitors in disease control in thymoma patients. A major limit for deciphering cellular and molecular events leading to the transformation of thymic epithelial cells or for testing drug candidates is the lack of reliable in vitro cell system. We analyzed protein expression and activation of key players of the Akt/ mTOR pathway namely Akt, mTOR, and P70S6K in eleven A, B and AB thymomas as well as in normal thymuses. While only Akt and phospho-Akt were expressed in normal thymuses, both Akt and mTOR were activated in thymomas. Phospho-P70S6K was expressed in all thymic tumors whatever their subtypes, and absent in normal thymus. Interestingly, we report the activation of Akt, mTOR and P70S6 proteins in primary thymic epithelial cells maintained for short period of time after their derivation from seven AB and B thymomas. Finally, we showed that rapamycin (100 nM) significantly reduced proliferation of thymoma- derived epithelial cells without inducing cell death. Our results suggest that the activation of the Akt/ mTOR pathway might participate to the cell proliferation associated with tumor growth. Ultimately, our data enhance the potential role of thymic epithelial cells derived from tissue specimens for in vitro exploration of molecular abnormalities in rare thymic tumors.

Systemic Therapy in Advanced Thymic Epithelial Tumors: Insights from the RYTHMIC Prospective Cohort

INTRODUCTION

Thymic epithelial tumors (TETs) are rare malignancies that may be aggressive and difficult to treat. In the advanced setting, systemic treatments may be delivered as primary therapy before surgery or definitive radiotherapy, as exclusive treatment when no focal treatment is feasible, or in the setting of recurrences. Réseau tumeurs THYMIques et Cancer (RYTHMIC) is the nationwide network for TETs in France. The objective of the study was to describe the modalities and analyze the efficacy of systemic treatments for patients with advanced TETs included in the RYTHMIC prospective database hosted by the French Thoracic Cancer Intergroup.

METHODS

All consecutive patients for whom systemic treatment was discussed at the RYTHMIC multidisciplinary tumor board from 2012 to 2015 and who received at least one cycle of treatment were included. The main end points were objective response and progression-free survival (PFS).

RESULTS

A total of 236 patients were included in this analysis. Of those 236 patients, 91 received primary chemotherapy, leading to response rates of 83% for thymomas and 75% for thymic carcinomas and a median PFS of 23.2 months. A strong predictor of longer PFS was histologic type of thymoma (p < 0.001). Exclusive chemotherapy was delivered to 54 patients. The response rates were 31% for thymomas and 37% for thymic carcinomas. The median PFS was 6.2 months, and it was correlated to response rate (p = 0.001). Systemic therapy for a first, second, third, and fourth recurrence was delivered to 114, 81, 51, and 27 patients, respectively. The response rates ranged between 15% and 39% for thymomas and 4% to 21% for thymic carcinomas. The median PFS times were 7.7, 6.2, 5.9, and 6.5 months, respectively.

CONCLUSION

Patients with advanced thymic malignancies may receive multiple lines of systemic therapy, with an opportunity for clinically relevant PFS rates for which objective response may be a surrogate. Our real-life study provides landmark efficacy data that are needed when designing clinical trials to assess innovative agents.

Design, synthesis and bioactivity investigation of tetrandrine derivatives as potential anti-cancer agents

Twenty-four 14-sulfonamide-tetrandrine derivatives as potential anti-cancer agents were synthesized. The synthetic derivatives were investigated for their cytotoxic activity against human cancer cell lines MDA-MB-231, PC3, WM9, HEL and K562. Initially, the IC50 values (50% inhibitory concentrations) of all of the compounds were determined. These derivatives exhibited potent, but distinct, inhibitory effects on the above-mentioned cell lines. Among them, compound 23, which was modified with a 2-naphthalenesulfonyl group at the 14-amino position, showed impressive inhibition of all five cancer cell lines, and especially of MDA-MB-231 cells with an IC50 value of 1.18 ± 0.14 μM. Further mechanism exploration showed that 23 induced potent apoptotic cell death on MDA-MB-231 cancer cells in a concentration-dependent manner. The results revealed that 23 might be a potential anti-cancer drug candidate.

Phase II Study of Everolimus in Patients With Thymoma and Thymic Carcinoma Previously Treated With Cisplatin-Based Chemotherapy

Purpose No effective salvage treatments are available for patients with advanced/recurrent thymoma (T) or thymic carcinoma (TC) who have progressed after platinum-based chemotherapy. This study evaluated the activity of everolimus in patients with advanced/recurrent T or TC previously treated with cisplatin-containing chemotherapy. Patients and Methods This was a single-arm, single-stage, open-label, multicenter, phase II trial. Patients received oral everolimus 10 mg/d until disease progression, unacceptable toxicity, or patient refusal. A Fleming phase II trial was designed. The null hypothesis of a true disease control rate (DCR) of 40% was tested against a one-sided alternative of a true DCR of 60% (α = β = 0.10): If disease control were achieved in ≥ 21 of the first 41 evaluable patients, everolimus could be recommended for further evaluation. Progression-free survival, overall survival, and safety were also evaluated. Results From 2011 to 2013, 51 patients were enrolled (T, n = 32; TC, n = 19). Complete remission was observed in one patient with TC, partial response in five patients (T, n = 3; TC, n = 2), and stable disease in 38 patients (T, n = 27; TC, n= 11), with a DCR of 88% (T,: 93.8%; TC, 77.8%). With a median follow up of 25.7 months, median progression-free survival was 10.1 months (T,: 16.6 months; TC, 5.6 months), and median overall survival was 25.7 months (T, not reached; TC, 14.7 months). Fourteen patients had a serious drug-related adverse event; of these patients, nine permanently discontinued treatment. Three patients died of pneumonitis while in the study. Immunohistochemical positivity for p4E-BP1 or insulin-like growth factor-1 receptor was statistically significantly related to a shorter survival. Conclusion Everolimus may induce durable disease control in a high percentage of patients with T or TC, albeit with a potential high risk of fatal pneumonitis.