Pharmacogenetic variants and risk of remdesivir-associated liver enzyme elevations in Million Veteran Program participants hospitalized with COVID-19

Remdesivir is the first US Food and Drug Administration (FDA)-approved drug for the treatment of coronavirus disease 2019 (COVID-19). We conducted a retrospective pharmacogenetic study to examine remdesivir-associated liver enzyme elevation among Million Veteran Program participants hospitalized with COVID-19 between March 15, 2020, and June 30, 2021. Pharmacogene phenotypes were assigned using Stargazer. Linear regression was performed on peak log-transformed enzyme values, stratified by population, adjusted for age, sex, baseline liver enzymes, comorbidities, and 10 population-specific principal components. Patients on remdesivir had higher peak alanine aminotransferase (ALT) values following treatment initiation compared with patients not receiving remdesivir. Remdesivir administration was associated with a 33% and 24% higher peak ALT in non-Hispanic White (NHW) and non-Hispanic Black (NHB) participants (p < 0.001), respectively. In a multivariable model, NHW CYP2C19 intermediate/poor metabolizers had a 9% increased peak ALT compared with NHW normal/rapid/ultrarapid metabolizers (p = 0.015); this association was not observed in NHB participants. In summary, remdesivir-associated ALT elevations appear to be multifactorial, and further studies are needed.

Phase II study of sagopilone (ZK-Epo) in patients with recurrent metastatic breast cancer (MBC)

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Background: Sagopilone is a novel, fully synthetic epothilone, which represents a new class of microtubule stabilizing agents. It has shown significant pre-clinical activity in taxane resistant breast cancer cell lines and in tumor models, as well as clinical activity in both taxane naïve and pretreated MBC. Methods: MBC patients who received ≤ 3 prior anthracycline and taxane containing chemotherapies were eligible. Sagopilone was given either at 16 mg/m2 (arm A) or at 22 mg/m2 (arm B, amended additional cohort) IV over 3 hours every 21 days for up to 6 cycles. The primary end point was tumor response by RECIST. The Simon 2-Stage design required 3 responders in the first 24 evaluable patients in stage 1 and 10 responders in 65 evaluable patients to declare success. Results: Between June 2006 and June 2008, 65 patients were enrolled and treated (39 in arm A, 26 in arm B). Majority of metastases were in lymph nodes (62%), liver (55%), bone (49%), lung (37%), and cutaneous sites (19%). Median number of cycles delivered was 2 (1–17). Neither arm met Stage 1 criteria for responders. Nevertheless, 2 patients in arm A and 1 in arm B had confirmed partial response, and lasted 4, 7, and 2 months, respectively. 26% patients in arm A, and 42% in arm B had stable disease. 42 patients discontinued study prior to cycle 6 due to progressive disease/death, 14 due to adverse events, and 1 due to other reasons. All 65 patients are evaluable for safety. Adverse events documented or reported in ≥ 20% patients are: sensory neuropathy 80% (23% grade 3), nausea 57% (no grade 3), fatigue 45% (12% grade 3), vomiting 29% (no grade 3), myalgia 28% (5% grade 3), diarrhea 25% (2% grade 3), insomnia 25% (no grade 3), pain in extremity 25% (2% grade 3), headache 23% (5% grade 3), arthralgia 22% (5% grade 3), constipation 22% (2% grade 3). Conclusions: Sagopilone had limited activity in these heavily pretreated MBC patients. It appeared tolerable at both dose levels.

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GRB7 and HER2 protein overexpression and breast cancer outcome

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Background: The growth factor receptor-bound protein-7 gene (GRB7) encodes a multi-domain signal transduction molecule and is located in close proximity to human epidermal growth factor receptor 2 (HER2) on chromosome 17q11–12. This study examines the roles of GRB7 protein in human breast cancer. Methods: We performed western blotting analysis of protein extracts from 563 annotated frozen breast tumors, collected from 1988 - 1998. GRB7 and HER2 bands were assigned low or high values compared to specific protein controls, and tubulin bands. Chi-square tests were used to test the hypothesis that there was no association between expression status of GRB7 or HER2 with clinical covariates and outcomes. Univariate Cox regression was performed to identify risk factors and Cox proportional hazards backward step model for variable selection to identify independent predictors of progression free survival. All P values were two sided. P values less than 0.05 were considered statistically significant. HER 2 gene amplification status was determined by fluorescence in situ hybridization (FISH). Results: GRB7 protein over-expression was associated with negative estrogen (< 5 fmole/mg protein) and progesterone receptor (< 10fmole/mg protein) status, higher grade (1, 2, or 3), larger primary tumor size (< 2.0 vs. > 2.0 cm), (more) axillary lymph node involvement (continuous), higher clinical stage (1, 2, 3, or 4) and shortened progression free survival (months). We found a discrepancy in HER2 and GRB7 protein over-expression. Isolated GRB7 protein over-expression correlated with inferior progression free survival, while HER2 protein over-expression without GRB7 protein over-expression did not. Multivariate analysis revealed that GRB7 over-expression was an independent predictor of progression free survival (hazard ratio 1.69: 95% confidence interval, 1.073 - 2.672; P = 0.0236). All 18 tumors submitted to FISH analysis that over-expressed both HER2 and GRB7 proteins and no tumors (0 / 10) with HER2 but no GRB7 protein over-expression demonstrated HER2 gene amplification. Conclusions: GRB7 protein over-expression is an independent adverse prognostic factor in breast cancer.

No significant financial relationships to disclose.

Characterization of the human suppressor of fused, a negative regulator of the zinc-finger transcription factor Gli

Drosophila Suppressor of fused (Su(fu)) encodes a novel 468-amino-acid cytoplasmic protein which, by genetic analysis, functions as a negative regulator of the Hedgehog segment polarity pathway. Here we describe the primary structure, tissue distribution, biochemical and functional analyses of a human Su(fu) (hSu(fu)). Two alternatively spliced isoforms of hSu(fu) were identified, predicting proteins of 433 and 484 amino acids, with a calculated molecular mass of 48 and 54 kDa, respectively. The two proteins differ only by the inclusion or exclusion of a 52-amino-acid extension at the carboxy terminus. Both isoforms were expressed in multiple embryonic and adult tissues, and exhibited a developmental profile consistent with a role in Hedgehog signaling. The hSu(fu) contains a high-scoring PEST-domain, and exhibits an overall 37% sequence identity (63% similarity) with the Drosophila protein and 97% sequence identity with the mouse Su(fu). The hSu(fu) locus mapped to chromosome 10q24-q25, a region which is deleted in glioblastomas, prostate cancer, malignant melanoma and endometrial cancer. HSu(fu) was found to repress activity of the zinc-finger transcription factor Gli, which mediates Hedgehog signaling in vertebrates, and to physically interact with Gli, Gli2 and Gli3 as well as with Slimb, an F-box containing protein which, in the fly, suppresses the Hedgehog response, in part by stimulating the degradation of the fly Gli homologue. Coexpression of Slimb with Su(fu) potentiated the Su(fu)-mediated repression of Gli. Taken together, our data provide biochemical and functional evidence for the hypothesis that Su(fu) is a key negative regulator in the vertebrate Hedgehog signaling pathway. The data further suggest that Su(fu) can act by binding to Gli and inhibiting Gli-mediated transactivation as well as by serving as an adaptor protein, which links Gli to the Slimb-dependent proteasomal degradation pathway.