RTOG 0525: Exploratory Subset Analysis from a Randomized Phase III Trial Comparing Standard (std) Adjuvant Temozolomide (TMZ) with a Dose-dense (dd) Schedule for Glioblastoma (GBM)

Purpose/Objective(s): RTwith TMZ is the standard for GBM. dd TMZ causes prolongedMGMTdepletion in mononuclear cells and possibly in tumor. The RTOG 0525 trial (ASCO 2011) did not show an advantage from dd TMZ for survival or progression free survival. We conducted exploratory, hypothesis-generating subset analyses to detect possible benefit from dd TMZ.Materials/Methods: Patients were randomized to std (150-200 mg/m2 x 5 d) or dd TMZ (75-100 mg/m2 x 21 d) q 4 weeks for 6- 12 cycles. Eligibility included age.18, KPS$ 60, and. 1 cm2 tissue for prospective MGMTanalysis for stratification. Furtheranalyses were performed for all randomized patients (''intent-to-treat'', ITT), and for all patients starting protocol therapy (SPT). Subset analyses were performed by RPA class (III, IV, V), KPS (90-100, = 50,\50), resection (partial, total), gender (female, male), and neurologic dysfunction (nf = none, minor, moderate).Results: No significant difference was seen for median OS (16.6 vs. 14.9 months), or PFS (5.5 vs. 6.7 months, p = 0.06). MGMT methylation was linked to improved OS (21.2 vs. 14 months, p\0.0001), and PFS (8.7 vs. 5.7 months, p\0.0001). For the ITT (n = 833), there was no OS benefit from dd TMZ in any subset. Two subsets showed a PFS benefit for dd TMZ: RPA class III (6.2 vs. 12.6 months, HR 0.69, p = 0.03) and nf = minor (HR 0.77, p = 0.01). For RPA III, dd dramatically delayed progression, but post-progression dd patients died more quickly than std. A similar pattern for nf = minor was observed. For the SPT group (n = 714) there was neither PFS nor OS benefit for dd TMZ, overall. For RPA class III and nf = minor, there was a PFS benefit for dd TMZ (HR 0.73, p = 0.08; HR 0.77, p = 0.02). For nf = moderate subset, both ITT and SPT, the std arm showed superior OS (14.4 vs. 10.9 months) compared to dd, without improved PFS (HR 1.46, p = 0.03; and HR 1.74, p = 0.01. In terms of methylation status within this subset, there were more methylated patients in the std arm of the ITT subset (n = 159; 32 vs. 24%). For the SPT subset (n = 124), methylation status was similar between arms.Conclusions: This study did not demonstrate improved OS for dd TMZ for any subgroup, but for 2 highly functional subgroups, PFS was significantly increased. These data generate the testable hypothesis that intensive treatment may selectively improve disease control in those most likely able to tolerate dd therapy. Interpretation of this should be considered carefully due to small sample size, the process of multiple observations, and other confounders.Acknowledgment: This project was supported by RTOG grant U10 CA21661, and CCOP grant U10 CA37422 from the National Cancer Institute (NCI)

Phase I-II trial of imatinib mesylate (Gleevec; STI571) in treatment of recurrent oligodendroglioma and mixed oligoastrocytoma. North central cancer treatment group study N0272 (ALLIANCE/NCCTG)

Purpose: To evaluate the pharmacokinetics and efficacy of imatinib in patients with recurrent oligodendroglial tumors. Methods: Patients with progressive WHO grade II-III recurrent tumors after prior RT and chemotherapy were eligible. A phase I dose-escalation study was conducted for patients on enzyme-inducing anticonvulsants (EIAC). A phase II study for non-EIAC patients utilized a fixed dose of 600 mg/D. Primary efficacy endpoint was 6-month progression-free survival (PFS6). A 2-stage design was utilized, with 90% power to detect PFS6 increase from 25 to 45%. Results: In the Phase I, maximum tolerated dose was not reached at 1200 mg/D. For phase II patients, overall PFS6 was 33% and median PFS 4.0 months (95% CI 2.1, 5.7). Median overall survival (OS) was longer in imatinib-treated patients compared with controls (16.6 vs. 8.0 months; HR = 0.64, 95% CI 0.41,1.0, p = 0.049), and longer in patients with 1p/19q-codeleted tumors (19.2 vs. 6.2 months, HR = 0.43, 95% CI 0.21,0.89, p = 0.019). Confirmed response rate was 3.9% (PR = 1; REGR = 1), with stable disease observed in 52.9%. At 600 mg/D, mean steady-state imatinib plasma concentration was 2513 ng/ml (95% CI 1831,3195). Grade 3\u20134 adverse events (hematologic, fatigue, GI, hypophosphatemia, or hemorrhage) occurred in 61%. Conclusions: Although adequate plasma levels were achieved, the observed PFS6 of 33% did not reach our pre-defined threshold for success. Although OS was longer in imatinib-treated patients than controls, this finding would require forward validation in a larger cohort. Imatinib might show greater activity in a population enriched for PDGF-dependent pathway activation in tumor tissue

Phase 1/2 trial of temsirolimus and sorafenib in the treatment of patients with recurrent glioblastoma: North Central Cancer Treatment Group Study/Alliance N0572

BACKGROUND: Mitogen-activated protein kinase (MAPK) activation and mammalian target of rapamycin (mTOR)-dependent signaling are hallmarks of glioblastoma. In the current study, the authors conducted a phase 1/2 study of sorafenib (an inhibitor of Raf kinase and vascular endothelial growth factor receptor 2 [VEGFR-2]) and the mTOR inhibitor temsirolimus in patients with recurrent glioblastoma. METHODS: Patients with recurrent glioblastoma who developed disease progression after surgery or radiotherapy plus temozolomide and with 642 prior chemotherapy regimens were eligible. The phase 1 endpoint was the maximum tolerated dose (MTD), using a cohorts-of-3 design. The 2-stage phase 2 study included separate arms for VEGF inhibitor (VEGFi)\u2013naive patients and patients who progressed after prior VEGFi. RESULTS: The MTD was sorafenib at a dose of 200 mg twice daily and temsirolimus at a dose of 20 mg weekly. In the first 41 evaluable patients who were treated at the phase 2 dose, there were 7 who were free of disease progression at 6 months (progression-free survival at 6 months [PFS6]) in the VEGFi-naive group (17.1%); this finding met the prestudy threshold of success. In the prior VEGFi group, only 4 of the first 41 evaluable patients treated at the phase 2 dose achieved PFS6 (9.8%), and this did not meet the prestudy threshold for success. The median PFS for the 2 groups was 2.6 months and 1.9 months, respectively. The median overall survival for the 2 groups was 6.3 months and 3.9 months, respectively. At least 1 adverse event of grade 653 was observed in 75.5% of the VEGFi-naive patients and in 73.9% of the prior VEGFi patients. CONCLUSIONS: The limited activity of sorafenib and temsirolimus at the dose and schedule used in the current study was observed with considerable toxicity of grade 653. Significant dose reductions that were required in this treatment combination compared with tolerated single-agent doses may have contributed to the lack of efficacy. Cancer 2018;124:1455-63. \ua9 2018 American Cancer Society

RTOG 0525: A randomized phase iii trial comparing standard adjuvant temozolomide (tmz) with a dose-dense (dd) schedule in newly diagnosed glioblastoma (gbm)

Radiotherapy with concomitant and adjuvant TMZ is the standard of care for newly diagnosed GBM. MGMT methylation status may be an important determinant of treatment response. This trial, conducted by the RTOG, EORTC, and NCCTG, determined if intensified TMZ improves survival (OS) or progression free survival (PFS) in all patients or specific to MGMT status. Eligibility criteria included age . 18 yrs, KPS ≥ 60, and existence of a tissue block with . 1cm2 tumor for prospective MGMT and retrospective molecular analysis. Patients were randomized to Arm 1: standard TMZ (150-200 mg/m2 x 5 d) or Arm 2: dd TMZ (75-100 mg/m2 x 21 d) q 4 wks for 6-12 cycles. Symptom burden, quality of life (QOL), and neurocognition were prospectively and longitudinally assessed in a patient subset. 833 patients were randomized (1173 registered). Inadequate tissue (n ¼ 144) was the most frequent reason for nonrandomization.No statistical difference was observed between Arms 1 and 2 for median OS (16.6, 14.9 mo, p ¼ 0.63), median PFS (5.5, 6.7 mo, p ¼ 0.06), or methylation status. MGMT methylation was associated with improved OS (21.2, 14 mo, p , 0.0001), PFS (8.7, 5.7 mo, p , 0.0001), and treatment response (p ¼ 0.012). Cox modeling identifiedMGMT status and RPA class as significant predictors of OS; treatment arm and radiation technique (EORTC vs. RTOG) were not. There was increased grade ≥ 3 toxicity in Arm 2 (19%, 27%, p ¼ 0.008), which was mostly lymphopenia and fatigue. This study did not demonstrate improved efficacy for dd TMZ for newly diagnosed GBM regardless of methylation status. However, it confirmed the prognostic significance of MGMT methylation in GBM, demonstrated the feasibility of tumor tissue collection, molecular stratification, and collection of patient outcomes in a large transatlantic intergroup trial, thereby establishing a viable clinical trial paradigm. Support: NCI U10 CA 21661 and U10 CA37422