Relation between plasma trough concentration of abiraterone and prostate-specific antigen response in metastatic castration-resistant prostate cancer patients

BACKGROUND

Abiraterone (ABI) is a major oral agent for the treatment of metastatic castration-resistant prostate cancer (mCRPC) patients but its systemic exposure is subject to a large inter-individual variability. We aimed to explore the relationship between ABI trough plasma concentration and prostate-specific antigen (PSA) response in mCRPC patients and to identify the critical determinants for its activity.

PATIENTS AND METHODS

This is a monocentric prospective observational study in mCRPC patients treated with ABI. The plasmatic concentration of ABI at steady state was measured using liquid chromatography with fluorescence detection. The primary objective was to study the relationship between mean ABI plasma exposure (ABI C_min) and 3-month PSA response.

RESULTS

From 2012 to 2016, 61 mCRPC patients were eligible for pharmacokinetic/pharmacodynamic assessment. Thirty-eight patients experienced PSA response (62%, [confidence interval {CI} 95% 50-78]). In univariate analysis, ABI C_min was 1.5-fold higher in responders: 12.0 ng/mL (CI 95% 9.4-15.6) versus 8.0 ng/mL (CI 95% 5.8-11.6; P = 0.0015). In multivariate analysis, only ABI C_min was independently associated with PSA response (odds ratio = 1.12 [CI 95% 1.01-1.25], P = 0.004). By receiver operating characteristic analysis, the optimal threshold for ABI C_min was 8.4 ng/mL. Progression-free survival (PFS) was significantly higher in patients with ABI C_min above 8.4 ng/mL (hazard ratio 0.55, [CI 95% 0.31-0.99], 12.2 [CI 95% 9.2-19.5] versus 7.4 [CI 95% 5.5-14.7] months otherwise, P = 0.044).

CONCLUSIONS

We showed that ABI trough concentration correlates with PSA response and PFS. Moreover, we could determine a cut-off value of plasmatic concentration for PSA response. Altogether, ABI concentration monitoring appears as a new approach to improve clinical outcome in mCPRC patients.

Vemurafenib pharmacokinetics and its correlation with efficacy and safety in outpatients with advanced BRAF-mutated melanoma

Vemurafenib is a BRAF kinase inhibitor approved for first-line treatment of metastatic BRAF (V600) -mutant melanoma. However, data on the pharmacokinetic/pharmacodynamic (PK/PD) relationship are lacking. The aim of this prospective, multicenter study was to explore the PK/PD relationship for vemurafenib in outpatients with advanced BRAF-mutated melanoma. Fifty-nine patients treated with single-agent vemurafenib were prospectively analyzed. Vemurafenib plasma concentration (n = 159) was measured at days 15, 30, 60, and 90 after treatment initiation. Clinical and biological determinants (including plasma vemurafenib concentration) for efficacy and safety were assessed using Cox's model and multivariate stepwise logistic regression. Median progression-free survival (PFS) and overall survival were 5.0 (95 % confidence interval [95 % CI] 2.0-6.0) and 11.0 (95% CI 7.0-16.0) months, respectively. Twenty-nine patients (49 %) experienced any grade ≥3 toxicity and the most frequent grade ≥2 toxicity was skin rash (37 %). Severe toxicities led to definitive discontinuation in seven patients (12 %). Grade ≥2 skin rash was not statistically associated with better objective response at day 60 (p = 0.06) and longer PFS (hazard ratio 0.47; 95 % CI 0.21-1.08; p = 0.075). Grade ≥2 skin rash was statistically increased in patients with ECOG  ≥ 1 (odds ratio 4.67; 95 % CI 1.39-15.70; p = 0.012). Vemurafenib concentration below 40.4 mg/L at day 15 was significantly associated with a shorter PFS (1.5 [0.5-5.5] vs. 4.5 [2-undetermined] months, p = 0.029). Finally, vemurafenib concentration was significantly greater in patients developing grade ≥2 rash (61.7 ± 25.0 vs. 36.3 ± 17.9 mg/L, p < 0.0001). These results suggest that early plasma drug monitoring may help identify outpatients at high risk of non-response or grade ≥ 2 skin rash.

Abstract 2038: Sunitinib impact on kinome profiles of peripheral blood mononuclear cells from renal cell carcinoma patients: Do molecular effects correlate with clinical data

Introduction: Sunitinib, a potent multi-tyrosine kinase (TK) inhibitor, is a standard first-line treatment for metastatic renal cell carcinoma (mRCC). In addition to its antiangiogenic activity, sunitinib is known to have immune-modulating properties especially on regulatory T-cells and tumor-infiltrating lymphocytes. However, data is sparse about sunitinib impact on peripheral lymphocytes and new data is needed to gain insights into the angiogenesis and immunity bidirectional link. This study aims to fill such a gap by investigating the clinical and intracellular modifications of sunitinib on peripheral blood mononuclear cells (PBMC) from naïve mRCC patients.

Methods: Initially, a retrospective study was conducted in 88 mRCC patients treated with first-line sunitinib therapy to assess the evolution of lymphocyte count (expressed as a ratio between Day 21 and Day 0 i.e. D21/D0) during the first cycle of treatment. A new prospective study was carried out to determine kinomic profiles in PBMC from 21 naïve mRCC patients and 12 healthy volunteers. TK activity profiles of PBMC lysates were generated on TK PamChip® microarrays. The ex vivo effect of sunitinib and its active metabolite SU12662 were also determined in PBMCs. All data were analyzed using BioNavigator software.

Results: The retrospective preliminary study showed that an increased D21/D0 lymphocytes ratio was significantly associated with a shorter Progression Free Survival (PFS) in multivariate analysis (p = 0.0023). In the prospective study, the phosphorylation level in PBMCs from mRCC patients was significantly lower than in healthy volunteers for 74 peptides (p&lt;0.05). Ex vivo exposure to sunitinib or SU12662 led to a decreased phosphorylation level for majority of peptides in PBMCs from mRCC patients. Moreover, sunitinib had a stronger inhibitory profile than SU12662 for 80 peptides (p&lt;0.05). The ex vivo sunitinib effect was statistically correlated with the IMDC (“Heng”) prognostic model and D21/D0 lymphocytes ratio and 53 and 16 peptides, respectively were found to be significant. Less ex vivo inhibition was associated with both a poor prognosis according to Heng and an increased D21/D0 lymphocytes ratio.

Conclusions: Our retrospective study shows a decreased lymphocyte count on D21 after sunitinib initiation is a favorable prognostic factor in mRCC patients. The kinomic analysis of TKs in PBMCs after ex vivo exposure to sunitinib correlates with both Heng prognostic score and lymphocyte D21/D0 ratio, suggesting that PBMCs could be an interesting biological matrix to seek future biomarkers regarding clinical efficacy of sunitinib. Further investigations are underway to determine the involvement of signaling pathways contributing to the inter-individual variability in kinomic profiles of PBMCs from mRCC patients treated with sunitinib.

Citation Format: Audrey Bellesoeur, Gaelle Noe, Audrey Thomas-Schoemann, Olivier Huillard, Faris Naji, Savithri Rangarajan, Alicja Puszkiel, Jerome Alexandre, François Goldwasser, Benoit Blanchet, Michel Vidal. Sunitinib impact on kinome profiles of peripheral blood mononuclear cells from renal cell carcinoma patients: Do molecular effects correlate with clinical data. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2038.

Effect of single post-ovulatory administration of levonorgestrel on gene expression profile during the receptive period of the human endometrium

The hypothesis that levonorgestrel (LNG) used as an emergency contraceptive interferes with endometrial receptivity remains unproven. We compared the endometrial gene expression profile during the receptive period after administering a single dose of LNG 1.5 mg or placebo on day 1 of the luteal phase. An endometrial biopsy was done on day LH+7 or LH+8 and samples were taken from seven volunteers, each one contributing with one cycle treated with placebo and another with LNG. The expression of 20 383 genes was determined using cDNA microarrays. Real-time RT-PCR was used 1) to confirm the differences found in DNA microarray analysis and 2) to determine the effect of LNG on transcript levels of C3, C4BPα, COX2, MAOA, S100A4, and SERPINB9, known to be upregulated during receptivity, and on cPLA2α, JAK1, JNK1, CTSL1, and GSTP1, known to respond to mifepristone. Additional endometrial biopsies were done during the pre-receptive (LH+3) and receptive (LH+7) period and samples were taken from eight untreated volunteers in order to determine the changes associated with acquisition of receptivity of 14 genes. Mean levels of PAEP, TGM2, CLU, IGF2, and IL6ST mRNAs increased after administering LNG while those of HGD, SAT1, EVA1, LOC90133, ANXA1, SLC25A29, CYB5A, CRIP1, and SLC39A14 decreased. Except for the level of ANXA1 transcript, all changes remained within the range observed in untreated controls, and none of the transcripts responding to mifepristone changed in response to LNG. Post-ovulatory administration of LNG caused minimal changes in gene expression profiling during the receptive period. Neither the magnitude nor the nature or direction of the changes endorses the hypothesis that LNG interferes with endometrial receptivity.

The progestin ST 1435--rapid metabolism in man

Parenterally administered ST 1435 (Nestorone) is highly potent for contraception, and ovulation can be inhibited with very low serum levels of ST 1435. Orally administered ST 1435 is ineffective in various laboratory animals, presumably due to extensive first-pass metabolism. Thus, ST 1435 has been proposed for lactational contraception, to be metabolized by the suckling infant. We have studied the metabolism of ST 1435 in female volunteers following oral (10 mg), intravenous (iv) (0.1 mg) and transdermal (4.5-9.0 mg) routes of ST 1435 administration. Preliminary studies using rats were performed to develop the methodology of high performance-liquid chromatography (HPLC) fractionation and ST 1435-RIA detection. Rat portal serum revealed 4 distinct peaks of immunoreactive material with the retention times (Rt's) of 7.5, 10, 14.5 and 17.5 min (ST 1435 = 10 min). In systemic serum, only the peak with the Rt of 7.5 min could be detected. Therefore, orally administered ST 1435 is very effectively metabolized by the rat liver; this also explains the previously observed lack of biological effects of oral ST 1435. Following oral administration of ST 1435 to two women, the Rt of the major peak was 10 min. The magnitude of the ST 1435 peak decreased rapidly, and at 24h following ingestion, no ST 1435 could be detected by this method. The t1/2 of ST 1435 was approximately 1-2h. In addition, two minor peaks with Rt's of 4.5 and 16 min could be detected with the ST 1435 RIA at 1-4h following oral ingestion. Competitive receptor binding assays using the human uterine progesterone receptors (hPR) revealed that the ST 1435 fraction exhibits strong binding affinity towards the hPR; thus, in the human, a small fraction of biologically active ST 1435 seems to escape from the first-pass metabolism following oral intake. Following iv and transdermal administration of ST 1435, the only detectable peak with ST 1435-RIA was that of ST 1435. Similar magnitude of the ST 1435 peaks following oral administration of 10 mg and iv administration of 0.1 mg indicated that the bioavailability of ST 1435 is low. These data seem to confirm the suspicion that orally administered ST 1435 is also rapidly metabolized in the human, therefore encouraging further evaluation of ST 1435 during lactation. However, the rapid metabolism seen after oral intake can be successfully circumvented by sustained parenteral administration of ST 1435.