Primary Malignant Brain Tumors following Systemic Malignancies: A Population-Based Analysis

Specific transport of temozolomide does not override DNA repair-mediated chemoresistance

Temozolomide (TMZ) a DNA alkylating agent, is the standard-of-care for brain tumors, such as glioblastoma multiforme (GBM). Although the physicochemical and pharmacokinetic properties of TMZ, such as chemical stability and the ability to cross the blood-brain barrier (BBB), have been questioned in the past, the acquired chemoresistance has been the main limiting factor of long-term clinical use of TMZ. In the present study, an L-type amino acid transporter 1 (LAT1)-utilizing prodrug of TMZ (TMZ-AA, 6) was prepared and studied for its cellular accumulation and cytotoxic properties in human squamous cell carcinoma, UT-SCC-28 and UT-SCC-42B cells, and TMZ-sensitive human glioma, U-87MG cells that expressed functional LAT1. TMZ-AA 6 accumulated more effectively than TMZ itself into those cancer cells that expressed LAT1 (UT-SCC-42B). However, this did not correlate with decreased viability of treated cells. Indeed, TMZ-AA 6, similarly to TMZ itself, required adjuvant inhibitor(s) of DNA-repair systems, O6-methylguanine-DNA methyl transferase (MGMT) and base excision repair (BER), as well as active DNA mismatch repair (MMR), for maximal growth inhibition. The present study shows that improving the delivery of this widely-used methylating agent is not the main barrier to improved chemotherapy, although utilizing a specific transporter overexpressed at the BBB or glioma cells can have targeting advantages. To obtain a more effective anticancer prodrug, the compound design focus should shift to altering the major DNA alkylation site or inhibiting DNA repair systems.

Deciphering Glioblastoma: Fundamental and Novel Insights into the Biology and Therapeutic Strategies of Gliomas

Gliomas constitute a diverse and complex array of tumors within the central nervous system (CNS), characterized by a wide range of prognostic outcomes and responses to therapeutic interventions. This literature review endeavors to conduct a thorough investigation of gliomas, with a particular emphasis on glioblastoma (GBM), beginning with their classification and epidemiological characteristics, evaluating their relative importance within the CNS tumor spectrum. We examine the immunological context of gliomas, unveiling the intricate immune environment and its ramifications for disease progression and therapeutic strategies. Moreover, we accentuate critical developments in understanding tumor behavior, focusing on recent research breakthroughs in treatment responses and the elucidation of cellular signaling pathways. Analyzing the most novel transcriptomic studies, we investigate the variations in gene expression patterns in glioma cells, assessing the prognostic and therapeutic implications of these genetic alterations. Furthermore, the role of epigenetic modifications in the pathogenesis of gliomas is underscored, suggesting that such changes are fundamental to tumor evolution and possible therapeutic advancements. In the end, this comparative oncological analysis situates GBM within the wider context of neoplasms, delineating both distinct and shared characteristics with other types of tumors.

Impact of prior cancer history on survival in brain malignancy: A propensity score-adjusted, population-based study

BACKGROUND

Individuals with a Prior Cancer History (PCH) are often excluded from clinical trials. However, a growing body of evidence suggests that prior cancer history does not present adverse outcomes on cancer patients. The evidence on the survival of brain cancer patients in this regard remains widely unknown.

METHODS

We conducted a retrospective cohort study to estimate the prevalence and impact of prior cancer on survival of patients diagnosed with brain cancer. Data of patients who were diagnosed with brain cancer as their first or second primary malignancy between 2000 and 2019 were extracted from the Surveillance, Epidemiology, and End Results (SEER) database. Propensity Score Matching (PSM) was used to ensure comparable baseline characteristics among the patients. Survival analysis was conducted using the Kaplan-Meier method, as well as multivariate Cox proportional hazard and multivariate competing risk models.

RESULTS

Out of 42 726 patients, 1189 (2.78%) had PCH. Genitourinary (40.4%), Breast (13.6%), Hematologic and Lymphatic (11.4%), and Gastrointestinal malignancies (11.3%) were the most common types of prior cancer. PCH served as a significant risk factor for Overall Survival (OS) (Adjusted Hazard Ratio [AHR] 1.26; 95% CI [1.15-1.39]; p < .001) but did not have a statistically significant impact on Brain Cancer-Specific Survival (BCSS) (AHR 0.97; 95% CI [0.88-1.07]; p = .54). Glioblastoma exhibited the most substantial and statistically significant impact on survival as compared to other histological types. Of all the organs systems, only prior Gastrointestinal and Hematologic and Lymphatic malignancies had a statistically significant impact on OS of patients.

CONCLUSION

Our findings indicate that PCH does not exert a substantial impact on the survival of brain cancer patients, except in cases involving gastrointestinal or hematologic and lymphatic PCH, or when the brain cancer is glioblastoma.