Long-term daily temozolomide with dose-dependent efficacy in MGMT promotor methylation negative recurrent high-grade astrocytoma

Combination chemoradiotherapy with temozolomide, vincristine, and interferon-β might improve outcomes regardless of O6-methyl-guanine-DNA-methyltransferase (MGMT) promoter methylation status in newly glioblastoma

Background

This investigator-initiated, open-label, single-arm, single-institute study was conducted to investigate the effectiveness of induction combination chemoradiotherapy and long-term maintenance therapy with temozolomide (TMZ) plus interferon (IFN)-β for glioblastoma.

Methods

The initial induction combination chemoradiotherapy comprised radiotherapy plus TMZ plus vincristine plus IFN-β. Maintenance chemotherapy comprised monthly TMZ, continued for 24–50 cycles, plus weekly IFN-β continued for as long as possible. The primary endpoint was 2-year overall survival (2y-OS). The study protocol was to be considered valid if the expected 2y-OS was over 38% and the lower limit of the 95% confidence interval (CI) was no less than 31.7% compared with historical controls, using Kaplan-Meier methods. Secondary endpoints were median progression-free survival (mPFS), median OS (mOS), 5-year OS rate (5y-OS), and mPFS and mOS classified according to MGMT promoter methylation status.

Results

Forty-seven patients were analyzed. The 2y-OS was 40.7% (95%CI, 27.5–55.4%). The mPFS and mOS were 11.0 months and 18.0 months, respectively, and 5y-OS was 20.3% (95%CI, 10.9–34.6%). The mPFS in groups with and without MGMT promoter methylation in the tumor was 10.0 months and 11.0 months (p = 0.59), respectively, and mOS was 24.0 months and 18.0 months (p = 0.88), respectively. The frequency of grade 3/4 neutropenia was 19.1%.

Conclusions

The 2y-OS with induction multidrug combination chemoradiotherapy and long-term maintenance therapy comprising TMZ plus IFN-β tended to exceed that of historical controls, but the lower limit of the 95%CI was below 31.7%. Although the number of cases was small, this protocol may rule out MGMT promoter methylation status as a prognostic factor.

Trial registration

University Hospital Medical Information Network (number UMIN000040599).

PI3Kγ inhibition suppresses microglia/TAM accumulation in glioblastoma microenvironment to promote exceptional temozolomide response

Precision medicine in oncology leverages clinical observations of exceptional response. Toward an understanding of the molecular features that define this response, we applied an integrated, multiplatform analysis of RNA profiles derived from clinically annotated glioblastoma samples. This analysis suggested that specimens from exceptional responders are characterized by decreased accumulation of microglia/macrophages in the glioblastoma microenvironment. Glioblastoma-associated microglia/macrophages secreted interleukin 11 (IL11) to activate STAT3-MYC signaling in glioblastoma cells. This signaling induced stem cell states that confer enhanced tumorigenicity and resistance to the standard-of-care chemotherapy, temozolomide (TMZ). Targeting a myeloid cell restricted an isoform of phosphoinositide-3-kinase, phosphoinositide-3-kinase gamma isoform (PI3Kγ), by pharmacologic inhibition or genetic inactivation disrupted this signaling axis by reducing microglia/macrophage-associated IL11 secretion in the tumor microenvironment. Mirroring the clinical outcomes of exceptional responders, PI3Kγ inhibition synergistically enhanced the anti-neoplastic effects of TMZ in orthotopic murine glioblastoma models. Moreover, inhibition or genetic inactivation of PI3Kγ in murine glioblastoma models recapitulated expression profiles observed in clinical specimens isolated from exceptional responders. Our results suggest key contributions from tumor-associated microglia/macrophages in exceptional responses and highlight the translational potential for PI3Kγ inhibition as a glioblastoma therapy.

Dose-dense temozolomide for recurrent high-grade gliomas: a single-center retrospective study

There are limited treatment modalities after high-grade gliomas recurrence. MGMT depletion modulated by dose-dense temozolomide (ddTMZ) remains a debated therapy for initial TMZ responders. Patients were selected retrospectively from our practice with diagnosis of high-grade gliomas (WHO grade III or IV), and were followed since the start of ddTMZ until death or change of therapy. Twenty-one patients were reviewed, with a median age of 47 (25-61) years and a median of 5.8 (1.5-38.8) cycles of ddTMZ. The majority were males (71.4%). Sixty-six percent received 21 on/28 off ddTMZ schedule, 28.6% daily, and 1 patient received a 7 days on/7 days off schedule. IDH mutation status was available for 18 (85.7%) patients, with 7 (33.3%) IDH mutant and 11 (52.5%) IDH wild type. MGMT methylation was assessed in 6 (28.6%) of the patients, being MGMT methylated in 3 (14.3%) patients, and non-methylated in 3 (14.3%) patients. The majority of patients (57.1%) were receiving ddTMZ in addition to other forms of therapy, including either bevacizumab (38.1%) or tumor-treating fields (TTFields) (19.1%). Overall ddTMZ was well tolerated, with few adverse events reported. The estimated median overall survival after ddTMZ start was 11 months. Median progression-free survival (PFS) was 6 months. Outcomes did not vary between patients receiving ddTMZ alone or those using TTFields or bevacizumab as concomitant therapy, but there was a trend to longer survival with the use of concomitant TTFields. Our results demonstrate benefit of ddTMZ after previous treatment with standard TMZ dosing with no apparent increase in treatment-related toxicities. In summary, ddTMZ should be considered in TMZ responsive patients and warrants further investigation.