Clinical outcomes and prognostic factors of patients with advanced mesothelioma treated in a phase I clinical trials unit

BACKGROUND

We have previously reported a prognostic score for patients in phase I trials in the Drug Development Unit, treated at the Royal Marsden Hospital (RPS). The RPS is an objective tool used in patient selection for phase I trials based on albumin, number of disease sites and LDH. Patients with mesothelioma are often selected for phase I trials as the disease remains localised for long periods of time. We have now reviewed the clinical outcomes of patients with relapsed malignant mesothelioma (MM) and propose a specific mesothelioma prognostic score (m-RPS) that can help identify patients who are most likely to benefit from early referral.

METHODS

Patients who participated in 38 phase I trials between September 2003 and November 2015 were included in the analysis. Efficacy was assessed by response rate, median overall survival (OS) and progression-free survival (PFS). Univariate (UVA) and multivariate analyses (MVA) were carried out to develop the m-RPS.

RESULTS

A total of 65 patients with advanced MM were included in this retrospective study. The PFS was 2.5 months (95% confidence interval [CI] 2.0-3.1 months) and OS was 8 months (95% CI 5.6-9.8 months). A total of four (6%) patients had RECIST partial responses, whereas 26 (40%) patients had RECIST stable disease >3 months. The m-RPS was developed comprising of three different prognostic factors: a neutrophil: lymphocyte ratio greater than 3, the presence of more than two disease sites (including lymph nodes as a single site of disease) and albumin levels less than 35 from the MVA. Patients each received a score of 1 for the presence of each factor. Patients in group A (m-RPS 0-1; n = 35) had a median OS of 13.4 months (95% CI 8.5-21.6), whereas those in group B (m-RPS 2-3; n = 30) had a median OS of 4.0 months (95% CI 2.9-7.1, P < 0.0001). A total of 56 (86%) patients experienced G1-2 toxicities, whereas reversible G3-4 toxicities were observed in 18 (28%) patients. Only 10 (15%) patients discontinued phase I trials due to toxicity.

CONCLUSIONS

Phase I clinical trial therapies were well tolerated with early signals of antitumour activity in advanced MM patients. The m-RPS is a useful tool to assess MM patient suitability for phase I trials and should now be prospectively validated.

Phase I Trials of Molecularly Targeted Agents: Should We Pay More Attention to Late Toxicities?

Purpose

Phase I trials traditionally aim at determining the recommended phase II dose (RP2D) using grade ≥ 3 toxicity data from cycle 1 (C1) only. This design dates from the era of conventional chemotherapy and may not be relevant for new molecularly targeted agents (MTAs) usually administered in a chronic fashion and for which late or moderate toxicities may deserve particular attention.

Patients and Methods

All consecutive patients treated in phase I trials of MTAs at the Royal Marsden Hospital and Institut Gustave Roussy between January 2005 and July 2008 were included. Gastrointestinal, skin, and clinical renal toxicities of any grade and grades 3 to 4 toxic events of any type occurring at any cycle on treatment were recorded. Doses administered, treatment interruptions, dose modifications, and prescription of comedications were analyzed.

Results

A total of 445 patients (1,566 cycles; median treatment duration, 55 days) were included in 36 eligible trials; 790 toxicities (590, grade 1; 176, grade, 2; 24 grades, 3 to 4) and 1,819 toxicities (1,521, grade 1; 265, grade 2; 33, grades 3 to 4) were recorded during and after C1, respectively; 57% of the grades 3 to 4 toxicities occurred after C1; 50% of patients presented their worst-grade toxicity after C1. The risk of grades 3 to 4 toxicity was 3% in cycles 1 to 6 and was almost null afterwards. No cumulative toxicities were observed. Median toxicity duration was 15 days, with comedication administered in 68% of events.

Conclusion

Moderate and severe toxicities occur regularly after the first cycle in phase I trials of MTAs and may deserve increased attention in the RP2D process for these agents.