Safety and efficacy of ribociclib plus letrozole in patients with HR+, HER2- advanced breast cancer: Results from the Spanish sub-population of the phase 3b CompLEEment-1 trial

BACKGROUND

Breast cancer is the most common malignancy and the second leading cause of cancer-related mortality in Spanish women. Ribociclib in combination with endocrine therapy (ET) has shown superiority in prolonging survival in patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC) vs. ET alone.

METHODS

CompLEEment-1 is a single-arm, open-label phase 3b trial evaluating ribociclib plus letrozole in a broad population of patients with HR+, HER2- ABC. The primary endpoints were safety and tolerability. Here we report data for Spanish patients enrolled in CompLEEment-1.

RESULTS

A total of 526 patients were evaluated (median follow-up: 26.97 months). Baseline characteristics showed a diverse population with a median age of 54 years. At study entry, 56.5% of patients had visceral metastases and 8.7% had received prior chemotherapy for advanced disease. Rates of all-grade and Grade ≥3 adverse events (AEs) were 99.0% and 76.2%, respectively; 21.3% of patients experienced a serious AE, and 15.8% of AEs led to treatment discontinuation. AEs of special interest of neutropenia, increased alanine aminotransferase, increased aspartate aminotransferase and QTcF prolongation occurred in 77.8%, 14.8%, 11.4% and 4.0% of patients, respectively. Patients aged >70 years experienced increased rates of all-grade and Grade ≥3 neutropenia and anemia. Efficacy results were consistent with the global study.

CONCLUSIONS

Results from Spanish patients enrolled in CompLEEment-1 are consistent with global data showing efficacy and a manageable safety profile for ribociclib plus letrozole treatment in patients with HR+, HER2- ABC, including populations of interest (NCT02941926).

TRIAL REGISTRATION

ClinicalTrials.gov NCT02941926.

Familial breast cancer in Spain: A retrospective study of family history and clinical/pathologic characteristics from the GEICAM “El Álamo III” project

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Background: Family history (FH) of breast cancer (BC), ovarian cancer (OC), and individual features (IF), like early age of onset, bilateral BC, coexistence of BC and OC, and triple negative BC (TNBC) younger than 50 years, are suspicion criteria of hereditary BC. Although it is assumed in the literature that 15-30% of BC cases can be familial BC (FBC), only 5-10% of BC are hereditary, explained by a germline mutation in BRCA1 or 2. Moreover, there is no international consensus to define FBC (e.g. number of relatives affected, age of onset), in contrast with, e.g. Lynch syndrome and Amsterdam/Bethesda criteria, in order to offer genetic counseling. In Spain, there are not population-based studies analyzing the real percentage of BC with familial and/or individual high risk features. Methods: A retrospective study based on 10,641 Spanish BC patients diagnosed from 1998-2001, collected in the “El Álamo III project”, was conducted. Specific data regarding FBC were analyzed: IF (age of onset, bilateral breast cancer, ovarian cancer and TNBC; and FH features (first and second degree relatives with BC and /or OC). Results: The Table summarizes the results. Conclusions: 21% of BC patients in Spain diagnosed from 1998 to 2001 have at least one relative with BC and/or OC. In addition, 2.8 % of patients with no FH of BC/OC fulfill high risk criteria. However, several study characteristics, such as 18% patients with no FH recorded, and lack of data regarding age of affected relatives, limit the interpretation of these results, being necessary to improve the family data collection in further “El Álamo” project studies. [Table: see text]

SOLTI NeoPARP: A phase II, randomized study of two schedules of iniparib plus paclitaxel and paclitaxel alone as neoadjuvant therapy in patients with triple-negative breast cancer (TNBC)

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Background: Iniparib is an anticancer agent with a mechanism of action still under investigation. A phase 2 randomized neoadjuvant study in patients (pts) with TNBC was designed to explore the activity and tolerability of two schedules of iniparib with weekly paclitaxel (PTX). Here we report the efficacy and safety results from a planned interim analysis (IA). Methods: The trial accrued a total of 141 pts in October 2011, of whom, 74 are included in this IA. All were chemo-naive, histologicallyconfirmed Stage II-IIIA TNBC (IIA 47%; IIB 35%; IIIA 16%) with a median age of 50 yr. Triple negative status was centrally confirmed [ER/PR <10%, HER2 IHC (0+, 1+) or FISH negative]. Pts were randomized (1:1:1) to receive weekly PTX (80 mg/m2, IV, d 1; N=25) alone or in combination with iniparib, either on a once weekly (QW) (11.2 mg/kg, IV, d 1; N=25) or twice weekly (BIW) (5.6 mg/kg, IV, d 1, 4; N=24) schedule. The total planned treatment duration was 12 wks. The IA endpoint is pathological complete response in the breast (pCR) as assessed by independent pathologists. Results: Two/2/3 pts in the PTX/QW/BIW arms, respectively, discontinued due to progressive disease per RECIST. Another 3/2/2 pts, respectively, discontinued due to investigator decision or an adverse event (AE). Thirteen pts presented with Grade 3/4 Treatment Emergent AE: 3 pts in PTX arm (1 neutropenia, 1 presyncope, 1 ALT elevation), 3 in QW arm (1 lymphopenia, 1 hyperkalemia, 1 pulmonary embolism), and 8 in the BIW arm (1 febrile neutropenia, 3 neutropenia, 1 aphonia, 1 syncope, 1 radius fracture and 1 vertigo). Laboratory Grade 3/4 neutropenia occurred in 4% of pts in PTX, 0% in QW and 21% of BIW arms, with 1/2/3 pts, respectively, requiring G-CSF usage. There were 4/7/6 pts in the PTX/QW/BIW arms with PTX dose modifications. Four pts (16%) in PTX arm, 4 pts (16%) in the QW arm and 6 pts (25%) in the BIW arm had confirmed pCR in the breast. Conclusions: In this IA population, the addition of iniparib regardless of the schedule to weekly PTX did not seem to add clinically significant toxicity. pCR rate in the breast is similar across treatment arms at this IA. NCT01204125.

CYP2D6*4 polymorphism as blood predictive biomarker of breast cancer relapse in patients receiving adjuvant tamoxifen

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Background: Polymorphisms in cytochrome P450 2D6 gene affect the plasma concentration of tamoxifen active metabolites (endoxifen). Some drugs are known to be CYP2D6 inhibitors. We aim to determine the relationship between CYP2D6*4 polymorphisms, concomitant CYP2D6 inhibitors use and clinical outcomes of breast cancer patients receiving adjuvant tamoxifen (TAM). Patients and Methods: CYP2D6*4 (1934 G>A+1) genotype was determinated from DNA of blood samples using PCR-RFLP technique and Taqman Allelic Discrimination Assay in a series of 84 breast cancer patients receiving adjuvant TAM. CYP2D6 inhibitors were recorded. Chi-square test and logistic regression models were used to determinate association between genotype, use of concomitant CYP2D6 inhibitors and disease relapse rate. Results: In our 84 patients series mean age was 51.5y. (33–71). 14.8% were stage I, 58.0% stage II and 27.2% stage III. 61.4% were nodes positive and 98.7% tumors had positive hormonal receptors. We observed disease recurrence in 36.9% of cases. The mean following-up was 5.5 y. Genotype frequency was: wt/wt (57.1%), wt/*4 (40.5%) and *4/*4 (2.4%). 50% (18 of 36) of patients with the wt/*4 + *4/*4 genotypes had disease relapse compared with 27% (13 of 48) with wt/wt genotype (P= 0.041). Only 6 patients received concomitants CYP2D6 inhibitors, mainly antidepressants, all of them with the wt/*4 genotype. 50% presented disease relapse. Clinical pathological variables were evaluated and significant relation was found between stage and disease relapse by univariate analysis (P= 0.001). We investigated whether CYP2D6*4 genotype and stage to diagnosis could influence in disease relapse. For these analyses we use as reference group the genotype wt/wt. We observed that combined genotype wt/*4 + *4/*4 was more strongly associated with disease recurrence than wt/wt genotype (adjusted hazard ratio [HR], 2.82, 95% confidence interval [CI] 1.0- 7.9) P= 0.049. Conclusions: Breast cancer patients with the CYP2D6 *4/*4 or wt/*4 genotype could have lower benefit of TAM adjuvant treatment and tend to have a higher risk of disease relapse. Pre-treatment CYP2D6 genotype determination from blood sample could predicts TAM clinical outcomes and help to oncologist in treatment decision.

No significant financial relationships to disclose.