Effect of cross-platform gene-expression, computational methods on breast cancer subtyping in PALOMA-2 and PALLET studies.

Intrinsic breast cancer molecular subtyping (IBCMS) provides significant prognostic information for patients with breast cancer and helps determine treatment. This study compared IBCMS methods on various gene-expression platforms in PALOMA-2 and PALLET trials. PALOMA-2 tumor samples were profiled using EdgeSeq and nanostring and subtyped with AIMS, PAM50, and research-use-only (ruo)Prosigna. PALLET tumor biopsies were profiled using mRNA sequencing and subtyped with AIMS and PAM50. In PALOMA-2 (n = 222), a 54% agreement was observed between results from AIMS and gold-standard ruoProsigna, with AIMS assigning 67% basal-like to HER2-enriched. In PALLET (n = 224), a 69% agreement was observed between results from PAM50 and AIMS. Different IBCMS methods may lead to different results and could misguide treatment selection; hence, a standardized clinical PAM50 assay and computational approach should be used.Trial number: NCT01740427.

PACE: A Randomized Phase II Study of Fulvestrant, Palbociclib, and Avelumab After Progression on Cyclin-Dependent Kinase 4/6 Inhibitor and Aromatase Inhibitor for Hormone Receptor-Positive/Human Epidermal Growth Factor Receptor-Negative Metastatic Breast Cancer.

PURPOSE: Cyclin-dependent kinase (CDK) 4/6 inhibitors (CDK4/6is) are an important component of treatment for hormone receptor-positive/human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (MBC), but it is not known if patients might derive benefit from continuation of CDK4/6i with endocrine therapy beyond initial tumor progression or if the addition of checkpoint inhibitor therapy has value in this setting. METHODS: The randomized multicenter phase II PACE trial enrolled patients with hormone receptor-positive/HER2- MBC whose disease had progressed on previous CDK4/6i and aromatase inhibitor (AI) therapy. Patients were randomly assigned 1:2:1 to receive fulvestrant (F), fulvestrant plus palbociclib (F + P), or fulvestrant plus palbociclib and avelumab (F + P + A). The primary end point was investigator-assessed progression-free survival (PFS) in patients treated with F versus F + P. RESULTS: Overall, 220 patients were randomly assigned between September 2017 and February 2022. The median age was 57 years (range, 25-83 years). Most patients were postmenopausal (80.9%), and 40% were originally diagnosed with de novo MBC. Palbociclib was the most common previous CDK4/6i (90.9%). The median PFS was 4.8 months on F and 4.6 months on F + P (hazard ratio [HR], 1.11 [90% CI, 0.79 to 1.55]; P = .62). The median PFS on F + P + A was 8.1 months (HR v F, 0.75 [90% CI, 0.50 to 1.12]; P = .23). The difference in PFS with F + P and F + P + A versus F was greater among patients with baseline ESR1 and PIK3CA alterations. CONCLUSION: The addition of palbociclib to fulvestrant did not improve PFS versus fulvestrant alone among patients with hormone receptor-positive/HER2- MBC whose disease had progressed on a previous CDK4/6i plus AI. The increased PFS seen with the addition of avelumab warrants further investigation in this patient population.

Overall Survival With Palbociclib Plus Letrozole in Advanced Breast Cancer.

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned coprimary or secondary analyses are not yet available. Clinical trial updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.PALOMA-2 demonstrated statistically and clinically significant improvement in progression-free survival with palbociclib plus letrozole versus placebo plus letrozole in estrogen receptor-positive/human epidermal growth factor receptor 2-negative (ER+/HER2-) advanced breast cancer (ABC). Here, we report results for the secondary end point overall survival (OS). Postmenopausal women (N = 666) with ER+/HER2- ABC without previous systemic therapy for ABC were randomly assigned 2:1 to palbociclib plus letrozole or placebo plus letrozole. After a median follow-up of 90.1 months, 405 deaths were observed and 155 patients were known to be alive. The median OS was 53.9 months (95% CI, 49.8 to 60.8) with palbociclib plus letrozole versus 51.2 months (95% CI, 43.7 to 58.9) with placebo plus letrozole (hazard ratio [HR], 0.96 [95% CI, 0.78 to 1.18]; stratified one-sided P = .34). An imbalance in the number of patients with unknown survival outcome between the treatment arms (13.3% v 21.2%, respectively) limited interpretation of OS results. With recovered survival data, the median OS was 53.8 (95% CI, 49.8 to 59.2) versus 49.8 months (95% CI, 42.3 to 56.4), respectively (HR, 0.92 [95% CI, 0.76 to 1.12]; one-sided P = .21). OS was not significantly improved with palbociclib plus letrozole compared with placebo plus letrozole.

Impact of BMI in Patients With Early Hormone Receptor-Positive Breast Cancer Receiving Endocrine Therapy With or Without Palbociclib in the PALLAS Trial.

PURPOSE: BMI affects breast cancer risk and prognosis. In contrast to cytotoxic chemotherapy, CDK4/6 inhibitors are given at a fixed dose, irrespective of BMI or weight. This preplanned analysis of the global randomized PALLAS trial investigates the impact of BMI on the side-effect profile, treatment adherence, and efficacy of palbociclib. METHODS: Patients were categorized at baseline according to WHO BMI categories. Neutropenia rates were assessed with univariable and multivariable logistic regression. Time to early discontinuation of palbociclib was analyzed with Fine and Gray competing risk models. Unstratified Cox models were used to investigate the association between BMI category and time to invasive disease-free survival (iDFS). 95% CIs were derived. RESULTS: Of 5,698 patients included in this analysis, 68 (1.2%) were underweight, 2,082 (36.5%) normal weight, 1,818 (31.9%) overweight, and 1,730 (30.4%) obese at baseline. In the palbociclib arm, higher BMI was associated with a significant decrease in neutropenia (unadjusted odds ratio for 1-unit change, 0.93; 95% CI, 0.91 to 0.94; adjusted for age, race ethnicity, region, chemotherapy use, and Eastern Cooperative Oncology Group at baseline, 0.93; 95% CI, 0.92 to 0.95). This translated into a significant decrease in treatment discontinuation rate with higher BMI (adjusted hazard ratio [HR] for 10-unit change, 0.75; 95% CI, 0.67 to 0.83). There was no significant improvement in iDFS with the addition of palbociclib to ET in any weight category (normal weight HR, 0.84; 95% CI, 0.63 to 1.12; overweight HR, 1.10; 95% CI, 0.82 to 1.49; and obese HR, 0.95; 95% CI, 0.69 to 1.30) in this analysis early in follow-up (31 months). CONCLUSION: This preplanned analysis of the PALLAS trial demonstrates a significant impact of BMI on side effects, dose reductions, early treatment discontinuation, and relative dose intensity. Additional long-term follow-up will further evaluate whether BMI ultimately affects outcome.

Long-Term Pooled Safety Analysis of Palbociclib in Combination with Endocrine Therapy for Hormone Receptor-Positive/Human Epidermal Growth Factor Receptor 2-Negative Advanced Breast Cancer: Updated Analysis with up to 5 Years of Follow-Up.

BACKGROUND: Previous studies demonstrated the tolerability of palbociclib plus endocrine therapy (ET). This analysis evaluated safety based on more recent cutoff dates and a longer palbociclib treatment exposure. PATIENTS AND METHODS: Data were pooled from three randomized studies of patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) advanced breast cancer (ABC), including postmenopausal women who had not received prior systemic treatment for advanced disease (PALOMA-1/-2) and pre- and postmenopausal women who had progressed on prior ET (PALOMA-3). RESULTS: Updated cutoff dates were December 21, 2017 (PALOMA-1), May 31, 2017 (PALOMA-2), and April 13, 2018 (PALOMA-3). Total person-years of treatment exposure were 1,421.6 with palbociclib plus ET (n = 872) and 528.4 with ET (n = 471). Any-grade neutropenia and infections were more frequent with palbociclib plus ET (82.1% and 59.2%, respectively) than with ET (5.1% and 39.5%). The hazard ratios were 1.6 (p = .0995) for grade 3/4 infections, 1.8 (p = .4358) for grade 3/4 viral infections, 1.4 (p = .0001) for infections, and 30.8 (p < .0001) for neutropenia. Febrile neutropenia was reported in 1.4% of patients receiving palbociclib plus ET. Cumulative incidence of all-grade hematologic adverse events in both arms peaked during the first year of treatment and plateaued over the 5 subsequent years. Interstitial lung disease was reported in 13 patients receiving palbociclib plus ET and 3 receiving ET. CONCLUSION: This 5-year, long-term analysis demonstrated that palbociclib plus ET has a consistent and stable safety profile and is a safe treatment for patients with HR+/HER2- ABC. IMPLICATIONS FOR PRACTICE: Several treatments for patients with breast cancer are associated with long-term or latent adverse events. This long-term, 5-year analysis demonstrated that palbociclib plus endocrine therapy has a consistent and stable safety profile without cumulative or delayed toxicities. These results further support palbociclib plus endocrine therapy as a safe and manageable treatment in clinical practice for patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer.

Treatment effect of palbociclib plus endocrine therapy by prognostic and intrinsic subtype and biomarker analysis in patients with bone-only disease: a joint analysis of PALOMA-2 and PALOMA-3 clinical trials.

PURPOSE: This analysis evaluated the relationship between treatment-free interval (TFI, in PALOMA-2)/disease-free interval (DFI, in PALOMA-3) and progression-free survival (PFS) and overall survival (OS, in PALOMA-3), treatment effect in patients with bone-only disease, and whether intrinsic subtype affects PFS in patients receiving palbociclib. METHODS: Data were from phase 3, randomized PALOMA-2 and PALOMA-3 clinical studies of hormone receptor‒positive/human epidermal growth factor receptor 2‒negative (HR+ /HER2-) advanced breast cancer (ABC) patients receiving endocrine therapy plus palbociclib or placebo. Subpopulation treatment effect pattern plot (STEPP) analysis evaluated the association between DFI and PFS and OS. PFS by luminal subtype and cyclin-dependent kinase (CDK) 4/6 or endocrine pathway gene expression levels were evaluated in patients with bone-only disease; median PFS and OS were estimated by the Kaplan-Meier method. RESULTS: Median durations of TFI were 37.1 and 30.9 months (PALOMA-2) and DFI were 49.2 and 52.0 months (PALOMA-3) in the palbociclib and placebo groups, respectively. Among the PALOMA-2 biomarker population (n = 454), 23% had bone-only disease; median PFS was longer with palbociclib versus placebo (31.3 vs 11.2 months; hazard ratio, 0.41; 95% CI 0.25‒0.69). The interaction effect of bone-only versus visceral disease subgroups on median PFS with palbociclib was not significant (P = 0.262). Among the PALOMA-3 biomarker population (n = 302), 27% had bone-only disease. STEPP analyses showed that palbociclib PFS benefit was not affected by DFI, and that palbociclib OS effect may be smaller in patients with short DFIs. Among patients who provided metastatic tumor tissues (n = 142), regardless of luminal A (hazard ratio, 0.23; 95% CI 0.11‒0.47; P = 0.0000158) or luminal B (hazard ratio, 0.26; 95% CI 0.12‒0.56; P = 0.000269) subtype, palbociclib improved PFS versus placebo. CONCLUSIONS: These findings support palbociclib plus endocrine therapy as standard of care for HR+ /HER2- ABC patients, regardless of baseline TFI/DFI or intrinsic molecular subtype, including patients with bone-only disease. TRIAL REGISTRATION: Pfizer (clinicaltrials.gov:NCT01740427, NCT01942135).

Outcomes in Clinically Relevant Patient Subgroups From the EMBRACA Study: Talazoparib vs Physician's Choice Standard-of-Care Chemotherapy.

BACKGROUND: Talazoparib is a poly(adenosine diphosphate-ribose) polymerase inhibitor that causes death in cells with breast cancer susceptibility gene 1 or 2 (BRCA1/2) mutations. METHODS: EMBRACA (NCT01945775) was a randomized phase III study comparing efficacy, safety, and patient-reported outcomes (PROs) of talazoparib (1 mg) with physician's choice of chemotherapy (PCT: capecitabine, eribulin, gemcitabine, vinorelbine) in locally advanced or metastatic breast cancer with a germline BRCA1/2 (gBRCA1/2) mutation. Prespecified patient subgroups were analyzed for progression-free survival, objective response, clinical benefit, duration of response, and safety. PROs were evaluated in hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) or triple-negative breast cancer (TNBC) subgroups. RESULTS: Of 431 patients, 287 were randomly assigned to talazoparib and 144 to PCT. Prespecified subgroup analyses showed prolonged progression-free survival with talazoparib (HR+/HER2-: hazard ratio = 0.47, 95% confidence interval = 0.32 to 0.71; TNBC: hazard ratio = 0.60, 95% confidence interval = 0.41 to 0.87) and greater objective response rate (odds ratio = 1.97 to 11.89), clinical benefit rate (odds ratio = 2.05 to 7.77), and duration of response with talazoparib in all subgroups. PROs in HR+/HER2- and TNBC subgroups showed consistent overall improvement and delay in time to definitive clinically meaningful deterioration with talazoparib vs PCT. Across subgroups, common adverse events included anemia, fatigue, and nausea with talazoparib and neutropenia, fatigue, and nausea with PCT. Seven patients (2.4%) receiving talazoparib had grade II alopecia and 22.7% had grade I alopecia. CONCLUSIONS: Across all patient subgroups with gBRCA-mutated advanced breast cancer, talazoparib demonstrated clinically significant superiority in outcomes compared with PCT.

Talazoparib in Patients with a Germline BRCA-Mutated Advanced Breast Cancer: Detailed Safety Analyses from the Phase III EMBRACA Trial.

BACKGROUND: In the EMBRACA phase III study (NCT01945775), talazoparib was associated with a significantly prolonged progression-free survival (PFS) compared with physician's choice of chemotherapy (PCT) in germline BRCA1/2-mutated HER2-negative advanced breast cancer (ABC). Herein, the safety profile of talazoparib is explored in detail. MATERIALS AND METHODS: Overall, 412 patients received ≥1 dose of talazoparib (n = 286) or PCT (n = 126). Adverse events (AEs) were evaluated, including timing, duration, and potential overlap of selected AEs. The relationship between talazoparib plasma exposure and grade ≥3 anemia was analyzed. Time-varying Cox proportional hazard models assessed the impact of dose reductions on PFS. Patient-reported outcomes (PROs) in patients with common AEs and health resource utilization (HRU) were assessed in both treatment arms. RESULTS: The most common AEs with talazoparib were hematologic (195 [68.2%] patients) and typically occurred within the first 3-4 months of receiving talazoparib. Grade 3-4 anemia lasted approximately 7 days for both arms. Overlapping grade 3-4 hematologic AEs were infrequent with talazoparib. Higher talazoparib exposure was associated with grade ≥3 anemia. Permanent discontinuation of talazoparib due to hematologic AEs was low (<2%). A total of 150 (52.4%) patients receiving talazoparib had AEs associated with dose reduction. Hematologic toxicities were managed by supportive care medication (including transfusion) and dose modifications. Among patients with anemia or nausea and/or vomiting AEs, PROs favored talazoparib. After accounting for the treatment-emergent period, talazoparib was generally associated with a lower rate of hospitalization and supportive care medication use compared with chemotherapy. CONCLUSION: Talazoparib was associated with superior efficacy, favorable PROs, and lower HRU rate versus chemotherapy in gBRCA-mutated ABC. Toxicities were manageable with talazoparib dose modification and supportive care. IMPLICATIONS FOR PRACTICE: Talazoparib was generally well tolerated in patients with germline BRCA-mutated HER2-negative advanced breast cancer in the EMBRACA trial. Common toxicities with talazoparib were primarily hematologic and infrequently resulted in permanent drug discontinuation (<2% of patients discontinued talazoparib due to hematologic toxicity). Hematologic toxicities typically occurred during the first 3-4 months of treatment and were managed by dose modifications and supportive care measures. A significant efficacy benefit, improved patient-reported outcomes, lower rate of health resource utilization and a tolerable safety profile support incorporating talazoparib into routine management of germline BRCA-mutated locally advanced/metastatic breast cancer.

Investigation of a cyanine dye assay for the evaluation of the biocompatibility of magnesium alloys by direct and indirect methods.

Magnesium and its alloys are promising candidates for a new generation of biodegradable metals in orthopaedic applications due to their excellent biocompatibility, biodegradability, and mechanical properties that are similar to natural bone. However, direct in vitro assessment of these materials in the presence of cells is complicated by degradation products from the alloy that lead to a false positive for the most commonly used cell adhesion and cell proliferation assays. In this paper, a cyanine dye was used to quantitatively evaluate the in vitro biocompatibility of a Mg AZ31 alloy by both direct and indirect methods. The cytotoxicity of the corrosion products was evaluated via an indirect method; a 25% decrease in cell viability compared to control samples was observed. Moreover, direct assessment of cell adhesion and proliferation showed a statistically significant increase in cell number at the surface after 72 h. In addition, the degradation rate and surface characteristics of the Mg AZ31 alloy were evaluated for both direct and indirect tests. The degradation rate was unaffected by the presence of cells while evidence of an increase in calcium phosphate deposition on the magnesium alloy surface in the presence of cells was observed. This study demonstrates that a cyanine dye based assay provides a more accurate assessment of the overall in vitro biocompatibility of biodegradable metals than the more commonly used assays reported in the literature to date.

Biomarker Analyses of Response to Cyclin-Dependent Kinase 4/6 Inhibition and Endocrine Therapy in Women with Treatment-Naïve Metastatic Breast Cancer.

PURPOSE: Preclinical data identified the cyclin-dependent kinase 4/6 (CDK4/6) inhibitor palbociclib as synergistic with antiestrogens in inhibiting growth of hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) human breast cancer models. This observation was validated clinically in the randomized, placebo-controlled, phase III PALOMA-2 study. EXPERIMENTAL DESIGN: To determine markers of sensitivity and resistance to palbociclib plus letrozole, we performed comprehensive biomarker analyses, investigating the correlation with progression-free survival (PFS), on baseline tumor tissues from PALOMA-2. RESULTS: Despite a broad biomarker search, palbociclib plus letrozole demonstrated consistent PFS gains versus placebo plus letrozole, with no single biomarker or cassette of markers associated with lack of benefit from combination treatment. Palbociclib plus letrozole confers efficacy on both luminal A and B patients. Higher CDK4 levels were associated with endocrine resistance which was mitigated by the addition of palbociclib, whereas lower PD-1 levels were associated with greater palbociclib plus letrozole benefit. Tumors with more active growth factor signaling, as exemplified by increased expression of FGFR2 and ERBB3 mRNA, appeared to be associated with greater PFS gain from the addition of palbociclib. CONCLUSIONS: These data underscore the importance of CDK4/6 signaling in HR+/HER2- breast cancer and suggest that the interplay between steroid hormone and peptide growth factor signaling could drive dependence on CDK4/6 signaling.See related commentary by Anurag et al., p. 3.

Progression-free Survival Outcome Is Independent of Objective Response in Patients With Estrogen Receptor-positive, Human Epidermal Growth Factor Receptor 2-negative Advanced Breast Cancer Treated With Palbociclib Plus Letrozole Compared With Letrozole: Analysis From PALOMA-2.

BACKGROUND: In PALOMA-2, palbociclib + letrozole significantly prolonged progression-free survival (PFS) versus placebo + letrozole in patients with estrogen receptor-positive/human epidermal growth factor receptor 2-negative (ER+/HER2-) advanced breast cancer (ABC). We investigated clinical outcomes of patients who achieved or did not achieve a confirmed objective response (OR) according to Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 (data cutoff: May 31, 2017). PATIENTS AND METHODS: Postmenopausal patients untreated for ER+/HER2- ABC were randomized 2:1 to palbociclib + letrozole or placebo + letrozole. Median PFS, median duration of OR, baseline characteristics, and palbociclib exposure were compared in patients with or without OR by treatment arm. RESULTS: In the intent-to-treat population, OR was achieved by 194 (44%) of 444 and 77 (35%) of 222 patients in the palbociclib and placebo arms, respectively (odds ratio, 1.5; 95% confidence interval [CI], 1.0-2.1; P = .0156). Regardless of treatment, more OR than non-OR patients had de novo metastatic disease (47%-50% and 28%-31%, respectively) and no prior endocrine therapy (55% and 35%-37%, respectively). Rates of palbociclib dose reduction owing to adverse events were similar regardless of OR (41% and 38%, respectively). Among the patients with OR during the study, approximately 50% achieved OR within the first 3 months regardless of treatment. The median PFS was significantly prolonged with palbociclib + letrozole versus placebo + letrozole in patients with measurable disease in both OR (37.2 months; 95% CI, 28.1 months to not estimable vs. 27.4 months; 95% CI, 22.2-31.1 months; hazard ratio, 0.66; 95% CI, 0.47-0.94; P = .009) and non-OR groups (10.9 months; 95% CI, 8.2-11.2 months vs. 5.6 months; 95% CI, 5.3-8.3 months; hazard ratio, 0.72; 95% CI, 0.54-0.97; P = .016). CONCLUSIONS: Palbociclib + letrozole provided significant clinical benefit versus placebo + letrozole to patients with ER+/HER2- ABC regardless of achieving RECIST-defined OR. Pfizer; ClinicalTrials.gov: NCT01740427.

Palbociclib with Letrozole in Postmenopausal Women with ER+/HER2- Advanced Breast Cancer: Hematologic Safety Analysis of the Randomized PALOMA-2 Trial.

BACKGROUND: PALOMA-2 confirmed that first-line palbociclib + letrozole improved progression-free survival (hazard ratio, 0.58; 95% confidence interval, 0.46-0.72) in postmenopausal women with estrogen receptor-positive (ER+)/human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC). This analysis evaluated palbociclib-associated hematologic adverse events (AEs) and provides insight on managing these AEs. MATERIALS AND METHODS: Postmenopausal women with ER+/HER2- ABC were randomly assigned 2:1 to letrozole (2.5 mg daily continuously) plus oral palbociclib (125 mg daily; 3 weeks on/1 week off) or placebo. Safety assessments were performed at baseline, days 1 and 15 (first two cycles) and day 1 of subsequent cycles, and included white blood cell, platelet, and absolute neutrophil count (ANC). RESULTS: PALOMA-2 randomized 666 women to palbociclib + letrozole (n = 444) or placebo + letrozole (n = 222). Neutropenia was the most common AE (95.3%) with palbociclib (grade 3, 55.6%; grade 4, 11.5%) and was managed by dose modifications; progression-free survival was similar between patients who experienced grade ≥ 3 neutropenia versus those who did not. Median (range) time to onset of neutropenia with palbociclib + letrozole was 15 (12-700) days (grade ≥ 3, 28.0 [12-854] days); median duration of each neutropenia episode grade ≥ 3 was 7.0 days. Asian ethnicity and low baseline ANC were associated with increased risk of grade 3/4 neutropenia with palbociclib (p < .001). CONCLUSION: Palbociclib + letrozole was generally well tolerated. Neutropenia, the most frequently reported AE in women with ER+/HER2- ABC, was mostly transient and manageable by dose modifications in patients who experienced grade ≥ 3 neutropenia, without appearing to compromise efficacy. (Pfizer; NCT01740427) IMPLICATIONS FOR PRACTICE: Palbociclib demonstrated an acceptable safety profile in PALOMA-2 in women with estrogen receptor-positive (ER+)/human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC) receiving first-line palbociclib + letrozole. Although hematologic adverse events (AEs) are typically expected with anticancer therapies and are often clinically significant, palbociclib-related hematologic AEs, particularly neutropenia (most frequent AE), were transient/manageable by dose reduction, interruption, or cycle delay, which is in contrast to the more profound neutropenia associated with chemotherapy. Palbociclib dose adjustments decreased hematologic AE severity without appearing to compromise efficacy, supporting palbociclib + letrozole as a first-line treatment for ER+/HER2- ABC.

Palbociclib Plus Letrozole as First-Line Therapy in Postmenopausal Asian Women With Metastatic Breast Cancer: Results From the Phase III, Randomized PALOMA-2 Study.

PURPOSE: In PALOMA-2, palbociclib plus letrozole significantly improved progression-free survival (PFS) as initial treatment of estrogen receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer. We assessed the benefit of palbociclib plus letrozole in Asians. PATIENTS AND METHODS: Of 666 enrolled postmenopausal women with estrogen receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer (no prior treatment of advanced disease), 95 were Asian. Patients were randomly assigned 2:1 to receive palbociclib plus letrozole or placebo plus letrozole. The primary end point was investigator-assessed PFS. Secondary end points were overall survival, objective response, patient-reported outcomes, pharmacokinetics, and safety. RESULTS: Median PFS was significantly longer in Asian patients who received palbociclib plus letrozole versus placebo plus letrozole (25.7 months [95% CI, 19.2 months to not estimable] v 13.9 months [95% CI, 7.4 to 22.0 months]; hazard ratio, 0.49; 95% CI, 0.27 to 0.87; P = .007). The most common toxicities with palbociclib were hematologic and more frequent among Asians versus non-Asians: neutropenia (any grade, 95.4% v 76.8%; grade 3/4, 89.2% v 62.5%), leukopenia (43.1% v 38.3%; 32.3% v 23.5%), and thrombocytopenia (27.7% v 13.5%; 4.6% v 1.1%). No Asians had febrile neutropenia. Discontinuation rates as a result of adverse events were similar among Asian and non-Asian patients who received palbociclib plus letrozole (10.8% and 9.5%). In Asians, quality of life (QOL) was maintained with no significant differences observed between treatments from baseline in breast cancer-specific QOL and general health status scores. Change from baseline in EuroQol five dimensions index scores was significantly higher with palbociclib plus letrozole (0.013 v -0.069; P = .0132). Geometric mean palbociclib trough concentration values were higher in Asians versus non-Asians (93.8 v 61.7 ng/mL). CONCLUSION: Consistent with the overall study population, the addition of palbociclib to letrozole significantly improved PFS in Asians. Hematologic toxicities were more frequent in Asians versus non-Asians but manageable with early dose modifications while maintaining QOL.

Long-term Pooled Safety Analysis of Palbociclib in Combination With Endocrine Therapy for HR+/HER2- Advanced Breast Cancer.

BACKGROUND: Palbociclib administered with endocrine therapy was tolerable when the overall incidence of toxicities was assessed separately for three PALOMA studies. This study analyzed pooled, longer-term PALOMA safety data longitudinally. METHODS: Data were pooled from three randomized phase II and III studies (ClinicalTrials.gov: NCT00721409, NCT01740427, NCT01942135) of hormone receptor-positive/human epidermal growth factor receptor 2‒negative advanced breast cancer patients. Front-line patients were randomly assigned to receive letrozole with/without palbociclib (PALOMA-1) or letrozole plus palbociclib/placebo (PALOMA-2). In PALOMA-3, patients with prior endocrine resistance received fulvestrant plus palbociclib/placebo. The cumulative event rates of adverse events (AEs), reporting up to 50 months of treatment, were assessed over time. RESULTS: Patients who received endocrine therapy (n = 1343) were included in this pooled analysis (872 were also treated with palbociclib, and 471 were not). The most common AEs with palbociclib plus endocrine therapy were neutropenia and infections (any grade, 80.6% and 54.7%, respectively), which were higher than in the endocrine monotherapy arm (any grade, 5.3% and 36.9%). The most common hematologic AEs (≥15.0% in the palbociclib arm) were more likely to be reported in the initial months of the study, after which time the cumulative event rate did not substantially increase. With palbociclib plus endocrine therapy, any grade AEs leading to permanent discontinuation over three years occurred in only 8.3% of patients. CONCLUSIONS: Based on these long-term safety analyses, there is no evidence of specific cumulative or delayed toxicities with palbociclib plus endocrine therapy, supporting the ongoing investigation of palbociclib plus endocrine therapy in early breast cancer (NCT02513394).

Palbociclib has no clinically relevant effect on the QTc interval in patients with advanced breast cancer.

The aim of this study was to assess the potential effects of palbociclib in combination with letrozole on QTc. PALOMA-2, a phase 3, randomized, double-blind, placebo-controlled trial, compared palbociclib plus letrozole with placebo plus letrozole in postmenopausal women with estrogen receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer. The study included a QTc evaluation substudy carried out as a definitive QT interval prolongation assessment for palbociclib. Time-matched triplicate ECGs were performed at 0, 2, 4, 6, and 8 h at baseline (Day 0) and on Cycle 1 Day 14. Additional ECGs were collected from all patients for safety monitoring. The QT interval was corrected for heart rate using Fridericia's correction (QTcF), Bazett's correction (QTcB), and a study-specific correction factor (QTcS). In total, 666 patients were randomized 2 : 1 to palbociclib plus letrozole or placebo plus letrozole. Of these, 125 patients were enrolled in the QTc evaluation substudy. No patients in the palbociclib plus letrozole arm of the substudy (N=77) had a maximum postbaseline QTcS or QTcF value of ≥ 480 ms, or a maximum increase from clock time-matched baseline for QTcS or QTcF values of ≥ 60 ms. The upper bounds of the one-sided 95% confidence interval for the mean change from time-matched baseline for QTcS, QTcF, and QTcB at all time points and at steady-state Cmax following repeated administration of 125 mg palbociclib were less than 10 ms. Palbociclib, when administered with letrozole at the recommended therapeutic dosing regimen, did not prolong the QT interval to a clinically relevant extent.

Separating the Siamese twins: using a π-shifted Sagnac interferometer to control the relative weight/influence of circular and linear birefringence on the loop transmission facilitating their measurement.

We demonstrate a novel method to measure circular birefringence (CB) and linear birefringence (LB) present simultaneously in the device under study. By using a π-shifted Sagnac interferometer, the scheme eliminates the dependence on incoming polarization and on the orientation angle of the linear birefringence. Moreover, due to different handedness symmetry/response of CB and LB to counter-propagating waves, the technique allows us to control the relative influence of the two birefringences leading to a requirement of only two measurements to determine both of them. Thus, comparing to Stokes polarimeters and other methods, our scheme has advantages when characterizing media containing both birefringences. Our findings are experimentally confirmed.

Influence of mixed organosilane coatings with variable RGD surface densities on the adhesion and proliferation of human osteosarcoma Saos-2 cells to magnesium alloy AZ31.

In the last decade, the use of magnesium and its alloys as biodegradable implant materials has become increasingly accepted. However, surface modification of these materials to control the degradation rate in the early stages of healing and improve their biocompatibility is crucial to the successful implementation of magnesium alloy implants in medicine. Cell adhesion and proliferation at the implant surface is a vital factor for successful integration of a biomaterial within the body. Cells accomplish this task by binding to ligands such as the arginine-glycine-aspartic acid peptide sequence (RGD) commonly found on adhesive proteins present in the extracellular matrix. In this paper, we report a biomimetic surface modification strategy involving deposition of a mixed organosilane layer on Mg AZ31 followed by covalent immobilization of RGD peptides through a heterobifunctional cross-linker molecule. Our results indicate that with optimized deposition conditions uniform organosilane coatings were successfully deposited on the Mg AZ31 substrate. Furthermore, we have demonstrated that the surface density of immobilized RGD can be varied by depositing organosilane layers from solutions containing two different organosilanes in specified ratios. Increases in cell adhesion and cell proliferation were observed on the surface modified substrates.

Palbociclib and Letrozole in Advanced Breast Cancer.

BACKGROUND: A phase 2 study showed that progression-free survival was longer with palbociclib plus letrozole than with letrozole alone in the initial treatment of postmenopausal women with estrogen-receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer. We performed a phase 3 study that was designed to confirm and expand the efficacy and safety data for palbociclib plus letrozole for this indication. METHODS: In this double-blind study, we randomly assigned, in a 2:1 ratio, 666 postmenopausal women with ER-positive, HER2-negative breast cancer, who had not had prior treatment for advanced disease, to receive palbociclib plus letrozole or placebo plus letrozole. The primary end point was progression-free survival, as assessed by the investigators; secondary end points were overall survival, objective response, clinical benefit response, patient-reported outcomes, pharmacokinetic effects, and safety. RESULTS: The median progression-free survival was 24.8 months (95% confidence interval [CI], 22.1 to not estimable) in the palbociclib-letrozole group, as compared with 14.5 months (95% CI, 12.9 to 17.1) in the placebo-letrozole group (hazard ratio for disease progression or death, 0.58; 95% CI, 0.46 to 0.72; P<0.001). The most common grade 3 or 4 adverse events were neutropenia (occurring in 66.4% of the patients in the palbociclib-letrozole group vs. 1.4% in the placebo-letrozole group), leukopenia (24.8% vs. 0%), anemia (5.4% vs. 1.8%), and fatigue (1.8% vs. 0.5%). Febrile neutropenia was reported in 1.8% of patients in the palbociclib-letrozole group and in none of the patients in the placebo-letrozole group. Permanent discontinuation of any study treatment as a result of adverse events occurred in 43 patients (9.7%) in the palbociclib-letrozole group and in 13 patients (5.9%) in the placebo-letrozole group. CONCLUSIONS: Among patients with previously untreated ER-positive, HER2-negative advanced breast cancer, palbociclib combined with letrozole resulted in significantly longer progression-free survival than that with letrozole alone, although the rates of myelotoxic effects were higher with palbociclib-letrozole. (Funded by Pfizer; PALOMA-2 ClinicalTrials.gov number, NCT01740427 .).

Ammonium ions improve the survival of glutamine-starved hybridoma cells.

BACKGROUND: As a consequence of a reprogrammed metabolism, cancer cells are dependent on the amino acid l-glutamine for their survival, a phenomenon that currently forms the basis for the generation of new, cancer-specific therapies. In this paper, we report on the role which ammonium ions, a product of glutaminolysis, play on the survival of l-glutamine-deprived Sp2/0-Ag14 mouse hybridoma cells. RESULTS: The supplementation of l-glutamine-starved Sp2/0-Ag14 cell cultures with either ammonium acetate or ammonium chloride resulted in a significant increase in viability. This effect did not depend on the ability of cells to synthesize l-glutamine, and was not affected by the co-supplementation with α-ketoglutarate. When we examined the effect of ammonium acetate and ammonium chloride on the induction of apoptosis by glutamine deprivation, we found that ammonium salts did not prevent caspase-3 activation or cytochrome c leakage, indicating that they did not act by modulating core apoptotic processes. However, both ammonium acetate and ammonium chloride caused a significant reduction in the number of l-glutamine-starved cells exhibiting apoptotic nuclear fragmentation and/or condensation. CONCLUSION: All together, our results show that ammonium ions promote the survival of l-glutamine-deprived Sp2/0-Ag14 cells and modulate late-apoptotic events. These findings highlight the complexity of the modulation of cell survival by l-glutamine, and suggest that targeting survival-signaling pathways modulated by ammonium ions should be examined as a potential anti-cancer strategy.

Inhibition of MCL-1 by obatoclax sensitizes Sp2/0-Ag14 hybridoma cells to glutamine deprivation-induced apoptosis.

For several cancer cell types, the lack of an adequate supply of the amino acidl-glutamine (Gln) triggers apoptosis, a phenomenon termed Gln addiction. In this report, we examined the role of the anti-apoptotic proteins of the B-cell lymphoma 2 (BCL-2) protein family in the survival of Sp2/0-Ag14 (Sp2/0) mouse hybridoma cells, a cell line that undergoes apoptosis within minutes of Gln deprivation. Western blot analysis revealed that myeloid cell leukaemia 1 (MCL-1) was expressed at much higher levels than BCL-2, B-cell lymphoma extra-large and BCL-2-like protein 2 making it the prominent pro-survival BCL-2 family member in this hybridoma. Gln deprivation triggered a progressive decrease in MCL-1 protein levels, which coincided with the decrease in Sp2/0 cell survival. Moreover, Sp2/0 cells were much more sensitive to the broad Bcl-2 homology domain-3 (BH3) mimetic obatoclax (which targets MCL-1) than to the more selective drug ABT-737 (which does not target MCL-1). Finally, we show that obatoclax sensitizes Sp2/0 cells to apoptosis following Gln starvation. All together, the data presented here reveal that modulation of the pro-survival protein MCL-1 is an important step in the sequence of events leading to the initiation of apoptosis in Gln-starved Sp2/0 cells. Cancer cells require an adequate supply ofl-glutamine for their survival. Using a mouse hybridoma cell line that is exquisitely sensitive to glutamine starvation, we show that the levels of the pro-survival BCL-2 family protein MCL-1 decrease upon glutamine starvation in a manner that correlates with the loss of cell viability. Moreover, inhibiting MCL-1 with the drug obatoclax sensitizes hybridoma cells to glutamine starvation. Thus, in some cancer cells, glutamine starvation triggers the inactivation of pro-survival proteins. Our data suggest that the combined inhibition of glutamine biosynthesis pathways and BCL-2 proteins may prove effective against some cancers.