A Simple Scoring System for Identifying Relapsed/Refractory Lymphoma Patients Prematurely Withdrawn from Phase I Trials: The Gustave Roussy Experience

Background: Treating relapsed/refractory non-Hodgkin and Hodgkin lymphoma in fit young and elderly patients represents a considerable challenge for clinicians. Combined cytotoxic agents are rapidly ineffective, especially when relapse occurs after autologous stem cell transplantation (ASCT). Alternative regimens are often sparse. In the era of personalized medicine, phase I clinical trials offer an alternative therapeutic option through a multitude of immunotherapy and targeted drugs in development. Phase I trials aim to determine the recommended phase II dose (RP2D) through toxicity and pharmacokinetic assessments. Documenting signal of activity is also a major objective, underlying the importance of including patients susceptible to remain on study until first lymphoma response evaluation (usually 6 weeks, 2 cycles). We aimed to assess a simple scoring system that could identify patients who will discontinue phase I studies before 6 weeks.

Patients and Methods: Data from all lymphoma patients treated within a phase I trial in Gustave Roussy (GR) Cancer Center were retrospectively collected. 83 consecutive patients were enrolled in 17 phase I trials at GR between January 2008 and May 2014. All patients had progressive lymphoma at time of enrollment, after a median of 3 prior therapeutic lines (range 1;13). 37 patients (45%) received an ASCT prior to phase I inclusion. Median age was 67 years (range: 23-92) and WHO performance status (PS) was 0 in 36 patients (43%), 1 in 43 patients (52%) and 2 in 4 patients (5%). Median time from lymphoma diagnosis to phase I inclusion was 47 months. Lymphoma histological subtypes were represented as follows: 21% Hodgkin lymphoma, 36% aggressive non-Hodgkin lymphoma (83% diffuse large B cell lymphoma, 17% T cell lymphoma), 24% indolent non-Hodgkin lymphoma (70% follicular lymphoma, 25% marginal zone lymphoma, 5% Waldenström macroglobulinemia) and 19% mantle cell lymphoma. Univariate analysis on this cohort allowed identifying simple factors significantly associated with overall survival (OS). A simple scoring system, predictive for OS was pre-established and validated through a multivariate analysis in 2 large cohorts of various hematological malignancies by our group. Statistical tests were conducted on this relapsed/refractory lymphoma cohort, to evaluate this score's OS and early study discontinuation predictive ability.

Results:

Within a median follow up of 19 months, median OS and progression free survival (PFS) were respectively 18 (CI95%: 12; 37) and 3 (CI95%: 1.7; 3.6) months. Best overall response rate (ORR) and disease control rate (DCR: objective response and stable disease rates) were respectively 18% and 61%.

Thirty-four patients (41%) experienced grade 3 or 4 adverse events and 7 patients (8%) a dose limiting toxicity (DLT). WHO performance status (PS) > 0 at inclusion, baseline albumin ≤ 35 g/l and baseline LDH ≥ 250 UI/L were significantly associated with poorer OS. The predefined GR prognostic score combined 2 simple variables, PS and baseline serum albumin (+1 if PS 0, +1 if albumin≤ 35 g/l). In our lymphoma cohort, patients with a GR score = 0 experienced significantly better OS compared to patients with a score = 1 and a score = 2 (37 months vs 17 months vs 9 months; p = 0.007).

This simple score, distinguishes patients most likely to remain on study for more than 6 weeks, considered as the minimum required period for response and toxicity evaluation (classical DLT and targeted therapies associated long term toxicities). Among patients prematurely withdrawn from clinical trials, 91% had a GR score ≥ 1 (p=0,007). Main study discontinuation reason was progressive disease (77%), drug related toxicity was only responsible for study discontinuation in 13 % of cases.

Conclusion: Our data demonstrate efficacy and safety of phase I clinical trials in lymphoma, thus offering an interesting alternative therapeutic option for fit young and elderly relapsed/refractory lymphoma patients. The GR simple score, can both help in selecting patients most likely to benefit from a phase I trial (better OS) and to determine the phase II recommended dose (reduced early trial discontinuation).