Intracerebral hemorrhage secondary to thrombocytopenia in a patient treated with temozolomide

Early platelet variation during concomitant chemo-radiotherapy predicts adjuvant temozolomide-induced thrombocytopenia in newly diagnosed glioblastoma patients

PURPOSE

Temozolomide (TMZ) is known to induce thrombocytopenia but no early predictive test has yet been clearly established. The aim of the study was to retrospectively identify and validate a threshold of early platelet variation predicting TMZ-induced thrombocytopenia during the TMZ phase in patients treated according to the Stupp protocol for glioblastoma.

METHODS

A training set was used to analyze variations in platelet count occurring from the first week (W1) to week 6 (W6) during radiotherapy. Our aim was to identify the most relevant platelet decrease associated with TMZ-induced thrombocytopenia ≤ 100 G/L at day 28 during the TMZ phase. The performance of the threshold was confirmed in an independent validation set.

RESULTS

Overall, 147 patients were included, 85 and 62 in the training and validation sets, respectively. Twenty-seven patients (18%) experienced at least one TMZ-induced thrombocytopenia in the TMZ phase. A platelet decrease at W6 ≥ 35% (∆W6 ≥ 35%) was identified as the best predictive variation with an AUC of 0.83, a sensitivity of 65%, and a specificity of 96%. In the validation set, ∆W6 ≥ 35% platelet variation was identified as an independent marker of TMZ-induced thrombocytopenia during the TMZ phase (OR 15.23 (95% CI 3.5-107.5)) corresponding to sensitivity of 77% (66-87%), specificity of 73% (62-84%), a positive predictive value of 42% (29-54%), and a negative predictive value of 92% (86-99%).

CONCLUSION

Platelet decrease at W6 ≥ 35% during the RT-TMZ phase is an early and simple predictive marker of clinically relevant TMZ-induced thrombocytopenia during TMZ maintenance.

Extended survival of glioblastoma patients after chemoprotective HSC gene therapy

Chemotherapy with alkylating agents for treating malignant disease results in myelosuppression that can significantly limit dose escalation and potential clinical efficacy. Gene therapy using mutant methylguanine methyltransferase (P140K) gene-modified hematopoietic stem and progenitor cells may circumvent this problem by abrogating the toxic effects of chemotherapy on hematopoietic cells. However, this approach has not been evaluated clinically. Here, we show efficient polyclonal engraftment of autologous P140K-modified hematopoietic stem and progenitor cells in three patients with glioblastoma. Increases in P140K-modified cells after transplant indicate selection of gene-modified hematopoietic repopulating cells. Longitudinal retroviral integration site (RIS) analysis identified more than 12,000 unique RISs in the three glioblastoma patients, with multiple clones present in the peripheral blood of each patient throughout multiple chemotherapy cycles. To assess safety, we monitored RIS distribution over the course of chemotherapy treatments. Two patients exhibited emergence of prominent clones harboring RISs associated with the intronic coding region of PRDM16 (PR domain-containing 16) or the 3' untranslated region of HMGA2 (high-mobility group A2) genes with no adverse clinical outcomes. All three patients surpassed the median survival for glioblastoma patients with poor prognosis, with one patient alive and progression-free more than 2 years after diagnosis. Thus, transplanted P140K-expressing hematopoietic stem and progenitor cells are chemoprotective, potentially maximizing the drug dose that can be administered.

A phase I study of LY317615 (enzastaurin) and temozolomide in patients with gliomas (EORTC trial 26054)

We report a phase 1 study to examine the safety and recommended dose of the oral protein kinase C-beta inhibitor (anti-angiogenic) enzastaurin in combination with single-agent temozolomide. The study was conducted in patients with recurrent glioblastoma or newly diagnosed disease that was not treatable with standard (chemo)radiotherapy. Patients were treated with standard dose temozolomide (200 mg/m(2) for 5 days every 4 weeks) together with daily oral enzastaurin. Three dose levels of enzastaurin were investigated: 250 mg daily (OD), 500 mg OD, and 250 mg twice daily (BID). Dose-limiting toxicity was determined in the first 2 cycles, but treatment continued until limiting toxicity or disease progression was identified. Twenty-eight patients were enrolled. No dose-limiting toxicity was noted at 250 mg OD or 500 mg OD. However, at 250 mg BID, 2 dose-limiting episodes of thrombocytopenia were noted. The recommended dose for enzastaurin in combination with standard 4-weekly temozolomide is therefore 500 mg OD. The pharmacokinetics of enzastaurin in combination with temozolomide was evaluated. Temozolomide did not appear to effect enzastaurin exposures at the 250 mg or 500 mg OD dose levels.