Tremelimumab for patients with chemotherapy-resistant advanced malignant mesothelioma: an open-label, single-arm, phase 2 trial

A phase I dose escalation trial of tremelimumab (CP-675,206) in combination with gemcitabine in chemotherapy-naive patients with metastatic pancreatic cancer

BACKGROUND

Tremelimumab (CP-675,206) is a fully human monoclonal antibody binding to cytotoxic T-lymphocyte-associated antigen 4 (CTLA4) on T cells that stimulates the immune system by blocking the CTLA4-negative regulatory signal. Combination with standard chemotherapy may strengthen antitumor therapy. This is a phase Ib, multisite, open-label, nonrandomized dose escalation trial evaluating the safety, tolerability, and maximum tolerated dose (MTD) of tremelimumab combined with gemcitabine in patients with metastatic pancreatic cancer.

PATIENTS AND METHODS

Gemcitabine (1000 mg/m(2) on days 1, 8, and 15 of each 28-day cycles) was administrated with escalating doses of i.v. tremelimumab (6, 10, or 15 mg/kg) on day 1 of each 84-day cycle for a maximum of 4 cycles. The first 18 patients had an initial 4-week gemcitabine-only lead-in period. Dose-limiting toxicities (DLTs) related to tremelimumab were evaluated during the first 6 weeks after the first dose of tremelimumab.

RESULTS

From June 2008 to August 2011, 34 patients were enrolled and received at least one dose of tremelimumab. No DLTs related to tremelimumab were observed at any dose, even when the maximum dose established for tremelimumab (15 mg/kg) was used. Most frequent grade 3/4 toxicities were asthenia (11.8%) and nausea (8.8%). Only one patient had a serious drug-related event (diarrhea with dehydration). The median overall survival was 7.4 months (95% confidence interval 5.8-9.4 months). At the end of treatment, two patients achieved partial response. Both patients received tremelimumab 15-mg/kg group (n = 2/19, 10.5%).

CONCLUSION

Tremelimumab plus gemcitabine demonstrated a safety and tolerability profile, warranting further study in patients with metastatic pancreatic cancer.

CLINICALTRIALSGOV ID

NCT00556023.

Systematic review of response rates of sarcomatoid malignant pleural mesotheliomas in clinical trials

RATIONALE

Malignant pleural mesothelioma is an almost universally fatal malignancy primarily related to asbestos exposure. Based on the differences in immunologic markers and gene expression between histologic subtypes of mesothelioma, and our clinical impression that response rates vary by histology, we decided to examine the reported response rates of mesothelioma subtypes.

OBJECTIVES

Our objective was to compare the response rates of sarcomatoid mesotheliomas to the overall response rates in published clinical trials.

METHODS

We searched PubMed for "mesothelioma" with the clinical trials filter selected. We included articles published between January 1, 2000 and March 20, 2014 in which subjects received first or second line systemic therapy for malignant pleural mesothelioma. Studies investigating multi-modality therapy including surgery were excluded. Response rates [including 95% confidence intervals (95% CI)] were estimated for the entire patient cohort and then separately for subjects with sarcomatoid tumors.

MEASUREMENTS AND MAIN RESULTS

We reviewed 544 publications of which 41 trials met our inclusion criteria. Eleven of these trials did not include patients with sarcomatoid mesothelioma (27% of eligible studies). The remaining 30 publications included 1475 subjects, 1011 with epithelioid tumors (68.5%), 203 with biphasic tumors (13.8%), 137 with sarcomatoid tumors (9.3%) and 124 with unknown subtypes (8.4%). In total, there were 323 responses (21.9%, complete and partial responses, 95% CI: 16.3, 28.8) to systemic therapy across all histological subtypes. In patients with sarcomatoid tumors (n=137) 19 responses were observed. This accounted for 5.9% of all responses and yields a 13.9% (95% CI: 8.6, 21.6) response rate for patients with sarcomatoid tumors. Multiple biases likely affected this systematic review.

CONCLUSION

Response rates for different histological subtypes of malignant pleural mesothelioma are infrequently reported. Partial and complete responses to systemic therapies appear to be less common among patients with sarcomatoid tumors.

Current issues in malignant pleural mesothelioma evaluation and management

Malignant pleural mesothelioma (MPM) is an uncommon disease most often associated with occupational asbestos exposure and is steadily increasing in worldwide incidence. Patients typically present at an older age, with advanced clinical stage and other medical comorbidities, making management quite challenging. Despite great efforts, the prognosis of MPM remains poor, especially at progression after initial treatment. Macroscopic complete resection of MPM can be achieved through extrapleural pneumonectomy (EPP) or extended (ie, radical) pleurectomy (e-P/D) in selected patients and can result in prolonged survival when incorporated into a multimodality approach. Given the morbidity associated with surgical resection of MPM, optimizing identification of appropriate patients is essential. Unfortunately, most patients are not candidates for EPP or e-P/D due to advanced stage, age, and/or medical comorbidity. Pemetrexed and platinum combination chemotherapy has become the cornerstone of therapy for patients with unresectable disease because the combination is associated with improved survival and quality of life in treated patients. However, MPM eventually becomes resistant to initial therapy, and benefit to further lines of therapy has not been substantiated in randomized clinical trials. Translational research has provided exciting insights into tumorigenesis, biomarkers, and immune response in MPM, leading to the development of multiple novel therapeutic agents that are currently in clinical trials. These advances hold the promise of a new era in the treatment of MPM and suggest that this disease will not be left behind in the war on cancer.

Second-line treatment in malignant pleural mesothelioma: translating the evidence into clinical practice

SUMMARY 

Nearly all patients with malignant pleural mesothelioma (MPM) progress during or after standard first-line treatment with pemetrexed plus a platinum compound. Second-line therapies are being increasingly used in clinical practice, but their role is still unproven, and the optimal regimens remain to be defined. Published studies have frequently severe limitations, due to the small number and to the heterogeneity of patients included. New treatment options are eagerly awaited. In selected cases with a prolonged disease control after first-line chemotherapy, re-treatment with pemetrexed seems to be the best option. In the other cases, patients should be enrolled whenever possible in clinical trials. Single-agent chemotherapy remains a reasonable option for palliation.

Immune therapies for malignant mesothelioma

Malignant mesothelioma (MM) is a rare disease which can develop in pleura, pericardium or peritoneum and in which the therapies available have limited efficacy and are associated with various side effects. Therefore, there is a need for more targeted and more effective therapies which are able to halt the disease progression. Among them immune therapies actively or passively directed against various structures of the MM cells seem to be particularly promising given their inhibitory potential demonstrated in both experimental and early clinical studies. Mesothelin in particular seem to be not only a biomarker of disease activity but also a therapeutic target. This review discusses the immune therapies currently investigated for MM.

Armed therapeutic viruses - a disruptive therapy on the horizon of cancer immunotherapy

For the past 150 years cancer immunotherapy has been largely a theoretical hope that recently has begun to show potential as a highly impactful treatment for various cancers. In particular, the identification and targeting of immune checkpoints have given rise to exciting data suggesting that this strategy has the potential to activate sustained antitumor immunity. It is likely that this approach, like other anti-cancer strategies before it, will benefit from co-administration with an additional therapeutic and that it is this combination therapy that may generate the greatest clinical outcome for the patient. In this regard, oncolytic viruses are a therapeutic moiety that is well suited to deliver and augment these immune-modulating therapies in a highly targeted and economically advantageous way over current treatment. In this review, we discuss the blockade of immune checkpoints, how oncolytic viruses complement and extend these therapies, and speculate on how this combination will uniquely impact the future of cancer immunotherapy.

Immune checkpoint blockade in malignant mesothelioma: A novel therapeutic strategy against a deadly disease?

Monoclonal antibodies that target immune checkpoints are undoubtedly changing the therapeutic landscape of different human malignancies. Here we comment on the effects of blocking cytotoxic T lymphocyte-associated protein 4 (CTLA4) by means of the monoclonal antibody tremelimumab in patients with refractory malignant mesothelioma, a deadly disease with no effective therapeutic options.