Medical treatment of malignant pleural mesothelioma relapses

Systemic treatment in patients with malignant pleural mesothelioma - real life experience

Background

Malignant pleural mesothelioma (MPM) is a rare, aggressive malignancy of the pleural cavity linked to asbestos exposure. The combination of pemetrexed and platinum is a standard first-line therapy for malignant pleural mesothelioma. Despite some progress, almost all MPM patients experience progression after first-line therapy. The second-line treatment is still being under discussion and there are very limited data available on the second-line and subsequent treatments.

Methods

The retrospective analysis included 57 patients (16 females and 41 males) from two Polish oncological institutions treated for advanced mesothelioma between 2013 and 2019. We analysed the efficacy of first-line and second-line therapy: progression-free survival (PFS), overall survival (OS), overall response rate (ORR).

Results

In the first-line treatment, 55 patients received pemetrexed-based chemotherapy (PBC) and two cisplatin in monotherapy. Patients’ characteristics at baseline: median age was 64.2 years, ECOG PS ≤ 1 (86.2%), epithelial histology (85.7%). Median PFS and OS were 7.6 months and 14 months, respectively. Patients with ECOG PS ≤ 1 vs > 1 had a longer median OS (14.8 months vs 9.7 months, p = 0.057). One-year OS and PFS were 60.9% and 32.0%, respectively. Disease control rate (DCR) was 82.5%. Response to first-line therapy: PFS ≥ 6 months and PFS ≥ 12 months had a significant impact on median OS. Twelve patients received second-line therapy (seven PBC and five other cytotoxic single agents: navelbine, gemcitabine, or adriamycin/vincristine/methotrexate triplet). Median PFS and OS were 3.7 months and 7.2 months, respectively. DCR was 83%. One-year OS and PFS were 37% and 16.7%, respectively.

In the group receiving PBC, OS was prolonged by 4.5 months compared to the non-PBC group (6.0 months vs 10.5 months, p = 0.47).

Conclusion

Patients who benefited from first-line therapy and had prolonged PFS at first-line and achieve PFS longer than 6 months at first-line should be offered second-line treatment. Consideration of retreatment with the same cytotoxic agent could to be a viable option when no other treatment are available.

Does size matter? -a population-based analysis of malignant pleural mesothelioma

Background

The 8^th edition staging system for malignant pleural mesothelioma (MPM) has been proposed. The size of tumor is not taken into consideration. We intend to elucidate the prognostic value of the size of MPM and evaluate the current staging system via the data of SEER database.

Methods

All cases of primary MPM were identified and extracted from the SEER database during the period of 2004–2016. The endpoints were overall survival (OS) and cancer-specific survival (CSS) which were analyzed using Kaplan-Meier method. Log-rank test and Cox regression were utilized to identify the prognostic factors.

Results

A total of 2,138 patients were included in the primary cohort. The 1-, 3- and 5-year survival rates of MPM were 39.4%, 11.8% and 3.8%. Older, male and advanced stage patients accounted for larger proportion of the cohort. Besides tumor extension, lymph node involvement and metastatic status, tumor size, pathological type and differentiation grade were significant prognostic factors. In the stratified analysis of tumor extension, size is a significant prognostic factor in T2 patients and indicates inferior survival outcomes. Surgery, chemotherapy and radiation can increase both OS and CSS in MPM patients. Triple combination treatments showed a superiority to other treatments.

Conclusions

Tumor size matters in the prognosis of MPM especially in the early stage of MPM patients. The adjusted TNM staging system incorporating tumor size has better accuracy than the 8^th edition IMIG system. However, some stages had not been fully identified. More cases of early stages are warranted for essential revision.

Randomized Study of Maintenance Pemetrexed Versus Observation for Treatment of Malignant Pleural Mesothelioma: CALGB 30901

BACKGROUND

The role of maintenance therapy for malignant pleural mesothelioma (MPM) is unknown. We performed a randomized phase II trial to determine if continuation of pemetrexed after first-line pemetrexed and platinum would improve progression-free survival (PFS).

PATIENTS AND METHODS

Eligible patients with unresectable MPM, without disease progression following 4 to 6 cycles of pemetrexed and platinum were randomized 1:1 to observation or continuation of pemetrexed until progression, stratified by number of cycles (< 6 or 6), cis- or carboplatin containing regimen, and histology. Study size was calculated based on the assumption that observation would produce a median PFS of 3 months and pemetrexed would yield median PFS of 6 months.

RESULTS

A total of 72 patients were registered from December 2010 to June 2016. The study closed early after 53 patients were randomized; 49 eligible (22 on the observation arm and 27 on the pemetrexed arm) were included in the analysis. The median PFS was 3 months (95% confidence interval [CI], 2.6-11.9 months) on observation and 3.4 months (95% CI, 2.8-9.8 months) on pemetrexed (hazard ratio [HR], 0.99; 95% CI, 0.51-1.90; P = .9733). The median overall survival (OS) was 11.8 months (95% CI, 9.3-28.7 months) for observation, and 16.3 months (95% CI, 10.5-26.0 months) for pemetrexed (HR, 0.86; 95% CI, 0.44-1.71; P = .6737). Grade 3 or 4 toxicities on the pemetrexed arm included anemia (8%), lymphopenia (8%), neutropenia (4%), and fatigue (4%). A higher baseline level of soluble mesothelin-related peptide was associated with worse PFS (HR, 1.86; 95% CI, 1.00-3.46; P = .049).

CONCLUSION

Maintenance pemetrexed following initial pemetrexed and platinum chemotherapy does not improve PFS in patients with MPM.