Real-world comparative effectiveness of palbociclib plus aromatase inhibitor in HR+/HER2- metastatic breast cancer.

Aim: Provide real-world data on palbociclib as evidence of effectiveness in patient populations from routine clinical practice. Methods: This was a retrospective, observational cohort study of patients with HR+/HER2- metastatic breast cancer treated with palbociclib plus aromatase inhibitor (AI) or AI alone as first-line therapy within the US Oncology Network. Results: Patients treated with palbociclib plus AI (n = 838) versus AI alone (n = 450) had a numerically longer median overall survival (42.1 vs 35.7 months; hazard ratio [HR] = 0.90 [95% CI: 0.75-1.07]; p = 0.117) and a significantly extended real-world progression-free survival (21.0 vs 15.7 months; HR = 0.75 [95% CI: 0.64-0.88]; p = 0.0002) after normalized inverse probability treatment weighting. Conclusion: These real-world results support the use of palbociclib plus AI as first-line treatment in routine clinical practice for patients with HR+/HER2- metastatic breast cancer.

What is this summary about? This summary describes how well palbociclib works when used with an aromatase inhibitor in the real-world setting for people with a certain type of breast cancer that has spread to other areas of the body. Palbociclib stops cancer cells from growing and dividing. An aromatase inhibitor prevents the body from making the hormone estrogen, which is needed for certain types of breast cancer cells to grow. Palbociclib with an aromatase inhibitor is a standard first treatment used for people with this type of breast cancer that needs estrogen to grow and has spread to other areas of the body. In clinics, doctors may not always prescribe the two treatments together. The study wanted to find out if using the two treatments together worked better than using an aromatase inhibitor alone in the real-world setting. What were the results? The results suggest that in this population of patients treated in a real-world setting, people with breast cancer that needs estrogen to grow and has spread to other areas of the body who were treated with palbociclib plus an aromatase inhibitor lived longer without their cancer getting worse than those treated with an aromatase inhibitor alone. What do the results of the study mean? The results support the use of palbociclib with an aromatase inhibitor as a first treatment for breast cancer that has spread to other areas of the body, rather than an aromatase inhibitor only.

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.

The effects of adding palbociclib to endocrine therapy to treat advanced breast cancer: a plain language summary of a study using the PALOMA-2 and PALOMA-3 trial results.

WHAT IS THIS SUMMARY ABOUT?: This is a summary of an article that reported results of a study using data from two phase 3 clinical trials called "PALOMA-2" and "PALOMA-3." Both PALOMA-2 and PALOMA-3 trials included women with HR+/HER2- advanced breast cancer. HR+/HER2- breast cancer means the breast cancer cells of these women have receptors for female sex hormones and little or no HER2 receptors. Both PALOMA trials tested the effect of adding a medication called palbociclib (brand name, Ibrance®) to a hormone therapy. Hormone therapy, also known as endocrine therapy, is a treatment that blocks or removes hormones that cause cancer cells to grow and divide. In both trials, women took endocrine therapy with either palbociclib or a placebo. WHAT WAS THE AIM OF THIS STUDY?: The researchers aimed to see if the results from the PALOMA trials were similar for subgroups of women in the 2 trials. The subgroups in the study included women who shared certain features about their cancer or treatment history, for example, women whose cancer had spread to the liver. For each subgroup, the study compared the results from the 2 treatment groups: (1) women who took palbociclib plus endocrine therapy, and (2) women who took placebo plus endocrine therapy. WHAT WERE THE RESULTS & WHAT DO THEY MEAN?: The same effect was found in all subgroups. Compared with those who took placebo, women who took palbociclib lived longer without their cancer getting worse (growing or spreading). Also, among women who had chemotherapy after stopping the trial treatment, those who took palbociclib started chemotherapy later than those who took placebo. Because palbociclib slows cancer growth and leads to tumor shrinkage, this may have played a part in starting chemotherapy later. These results show that palbociclib plus endocrine therapy is better at slowing the progression of advanced HR+/HER2- breast cancer than endocrine therapy alone. This can be said for women with different advanced HR+/HER2- breast cancer features and treatment history. Overall, the results support women taking palbociclib with an endocrine therapy if they have advanced HR+/HER2- breast cancer.

Real-World Tumor Response of Palbociclib in Combination With an Aromatase Inhibitor as First-Line Therapy in Pre/Perimenopausal Women With Metastatic Breast Cancer.

BACKGROUND: Limited real-world data exist regarding the efficacy of palbociclib in combination with endocrine therapy in pre/perimenopausal women with metastatic breast cancer. OBJECTIVE: We aimed to compare real-world tumor responses among pre/perimenopausal women who initiated palbociclib plus an aromatase inhibitor (AI) or AI monotherapy as first-line treatment for hormone receptor-positive/human epidermal growth factor receptor 2-negative metastatic breast cancer. METHODS: This retrospective observational cohort study (NCT05012644) used electronic health record data from The US Oncology Network. Tumor responses were determined based on treating clinicians' assessments of radiologic evidence for changes in disease burden. Normalized inverse probability treatment weighting was used to balance baseline characteristics between treatment cohorts. RESULTS: Of 196 pre/perimenopausal women, 116 and 80 were in the palbociclib plus AI cohort and AI cohort, respectively. Real-world response rates (complete or partial response) were 52.1% and 46.2%, respectively (odds ratio, 1.27 [95% confidence interval 0.72‒2.24]). Among patients with one or more tumor assessments on treatment, real-world response rates were 60.0% in the palbociclib plus AI cohort (n = 103) and 49.9% in the AI cohort (n = 71; odds ratio, 1.51 [95% confidence interval 0.82‒2.77]). CONCLUSIONS: This real-world analysis suggests that pre/perimenopausal patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative metastatic breast cancer appear more likely to respond to palbociclib plus AI versus AI alone as first-line therapy, which may support the combination as a standard-of-care treatment for this patient population.

Palbociclib (Ibrance^®) is a medicine for patients with metastatic breast cancer (MBC). Metastatic means that the cancer has spread to other places in the body. Patients take palbociclib with hormone therapy, such as an aromatase inhibitor (AI). Palbociclib plus an AI is a treatment for a type of MBC called HR+/HER2‒ MBC. HR+/HER2‒ stands for hormone receptor positive, human epidermal growth factor receptor 2 negative. Researchers wanted to observe responses to treatment in routine clinical practice among women with HR+/HER2­ MBC who had not reached menopause. A response is if a tumor shrinks or disappears after treatment. This study used healthcare information reported in electronic medical records of patients seen by doctors in The US Oncology Network. This study included 196 women with HR+/HER2­ MBC who had not reached menopause and had not received prior treatment for MBC. A total of 116 women received palbociclib plus an AI, and 80 women received an AI alone. Researchers used standard statistical approaches to balance baseline characteristics between the two treatment groups. These adjustments made the groups more similar so that researchers could compare treatment responses. Sixty percent of patients who took palbociclib plus an AI responded, compared with 50% of patients who took an AI alone. These results suggest that palbociclib plus an AI may benefit women with HR+/HER2‒ MBC who have not reached menopause.

Overall Survival and Updated Results for Sunitinib Compared With Interferon Alfa in Patients With Metastatic Renal Cell Carcinoma.

PURPOSE: A randomized, phase III trial demonstrated superiority of sunitinib over interferon alfa (IFN-α) in progression-free survival (primary end point) as first-line treatment for metastatic renal cell carcinoma (RCC). Final survival analyses and updated results are reported. PATIENTS AND METHODS: Seven hundred fifty treatment-naïve patients with metastatic clear cell RCC were randomly assigned to sunitinib 50 mg orally once daily on a 4 weeks on, 2 weeks off dosing schedule or to IFN-α 9 MU subcutaneously thrice weekly. Overall survival was compared by two-sided log-rank and Wilcoxon tests. Progression-free survival, response, and safety end points were assessed with updated follow-up. RESULTS: Median overall survival was greater in the sunitinib group than in the IFN-α group (26.4 v 21.8 months, respectively; hazard ratio [HR] = 0.821; 95% CI, 0.673 to 1.001; P = .051) per the primary analysis of unstratified log-rank test (P = .013 per unstratified Wilcoxon test). By stratified log-rank test, the HR was 0.818 (95% CI, 0.669 to 0.999; P = .049). Within the IFN-α group, 33% of patients received sunitinib, and 32% received other vascular endothelial growth factor-signaling inhibitors after discontinuation from the trial. Median progression-free survival was 11 months for sunitinib compared with 5 months for IFN-α (P < .001). Objective response rate was 47% for sunitinib compared with 12% for IFN-α (P < .001). The most commonly reported sunitinib-related grade 3 adverse events included hypertension (12%), fatigue (11%), diarrhea (9%), and hand-foot syndrome (9%). CONCLUSION: Sunitinib demonstrates longer overall survival compared with IFN-α plus improvement in response and progression-free survival in the first-line treatment of patients with metastatic RCC. The overall survival highlights an improved prognosis in patients with RCC in the era of targeted therapy.

Effect of palbociclib plus endocrine therapy on time to chemotherapy across subgroups of patients with hormone receptor‒positive/human epidermal growth factor receptor 2‒negative advanced breast cancer: Post hoc analyses from PALOMA-2 and PALOMA-3.

BACKGROUND: Previous analyses from the PALOMA-2 and PALOMA-3 studies showed that palbociclib (PAL) plus endocrine therapy (ET) prolongs time to first subsequent chemotherapy (TTC) versus placebo (PBO) plus ET in the overall population of patients with hormone receptor‒positive/human epidermal growth factor receptor 2‒negative (HR+/HER2-) advanced breast cancer (ABC). Here, we evaluated TTC in relevant patient subgroups. METHODS: These post hoc analyses evaluated TTC by subgroup using data from 2 randomized, phase 3 studies of women with HR+/HER2- ABC. In PALOMA-2, postmenopausal patients previously untreated for ABC were randomized 2:1 to receive PAL (125 mg/day, 3/1-week schedule) plus letrozole (LET; 2.5 mg/day; n = 444) or PBO plus LET (n = 222). In PALOMA-3, premenopausal or postmenopausal patients whose disease had progressed after prior ET were randomized 2:1 to receive PAL (125 mg/day, 3/1-week schedule) plus fulvestrant (FUL; 500 mg; n = 347) or PBO plus FUL (n = 174). RESULTS: First subsequent chemotherapy was received by 35.5% and 56.2% in PALOMA-2 and PALOMA-3 after progression on palbociclib plus ET or placebo plus ET. Across all subgroups analyzed, the median progression-free survival (PFS) was longer in the PAL plus ET arm than the PBO plus ET arm. TTC was longer with PAL plus ET versus PBO plus ET across the same patient subgroups in both studies. CONCLUSIONS: Across all subgroups, PAL plus ET versus PBO plus ET had longer median PFS and resulted in prolonged TTC in both the PALOMA-2 and PALOMA-3 studies. Pfizer Inc (NCT01740427, NCT01942135).

Overall Survival with Palbociclib and Fulvestrant in Women with HR+/HER2- ABC: Updated Exploratory Analyses of PALOMA-3, a Double-blind, Phase III Randomized Study.

PURPOSE: To conduct an updated exploratory analysis of overall survival (OS) with a longer median follow-up of 73.3 months and evaluate the prognostic value of molecular analysis by circulating tumor DNA (ctDNA). PATIENTS AND METHODS: Patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) advanced breast cancer (ABC) were randomized 2:1 to receive palbociclib (125 mg orally/day; 3/1 week schedule) and fulvestrant (500 mg intramuscularly) or placebo and fulvestrant. This OS analysis was performed when 75% of enrolled patients died (393 events in 521 randomized patients). ctDNA analysis was performed among patients who provided consent. RESULTS: At the data cutoff (August 17, 2020), 258 and 135 deaths occurred in the palbociclib and placebo groups, respectively. The median OS [95% confidence interval (CI)] was 34.8 months (28.8-39.9) in the palbociclib group and 28.0 months (23.5-33.8) in the placebo group (stratified hazard ratio, 0.81; 95% CI, 0.65-0.99). The 6-year OS rate (95% CI) was 19.1% (14.9-23.7) and 12.9% (8.0-19.1) in the palbociclib and placebo groups, respectively. Favorable OS with palbociclib plus fulvestrant compared with placebo plus fulvestrant was observed in most subgroups, particularly in patients with endocrine-sensitive disease, no prior chemotherapy for ABC and low circulating tumor fraction and regardless of ESR1, PIK3CA, or TP53 mutation status. No new safety signals were identified. CONCLUSIONS: The clinically meaningful improvement in OS associated with palbociclib plus fulvestrant was maintained with >6 years of follow-up in patients with HR+/HER2- ABC, supporting palbociclib plus fulvestrant as a standard of care in these patients.

Real-World Data of Palbociclib in Combination With Endocrine Therapy for the Treatment of Metastatic Breast Cancer in Men.

This report examined the benefits and risks of palbociclib plus endocrine therapy (ET) in men with hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (MBC). Palbociclib was evaluated using three independent data sources: real-world data from pharmacy and medical claims, a de-identified real-world data source derived from electronic health records (EHRs), and a global safety database. From medical and pharmacy records, 1,139 men with MBC were identified; in the first-line setting, median duration of treatment was longer with palbociclib plus ET (n = 37, 8.5 months, 95% confidence interval (CI), 4.4-13.0) than ET alone (n = 214, 4.3 months, 95% CI, 3.0-5.7) and specifically, was longer with palbociclib plus letrozole (n = 26, 9.4 months, 95% CI, 4.4-14.0) than letrozole alone (n = 63, 3.0 months, 95% CI, 1.8-4.8). In the EHR-derived database, 59 men received treatment for MBC; real-world response across all lines of therapy in the metastatic setting was reported in 4 of 12 patients (33.3%) in the palbociclib plus ET group vs. 1 of 8 (12.5%) patients in the ET group. Review of the global safety database did not identify any new safety signals in palbociclib-treated men. Real-world data indicated that men with MBC benefit from palbociclib plus ET, with a safety profile consistent with previous observations in women with MBC. Collective data on palbociclib in women and men in this report, including clinical trial data, real-world data, and a well-established risk/benefit profile, led to US approval of an expansion of the palbociclib indication to include men with MBC.

Palbociclib plus letrozole as treatment for postmenopausal women with hormone receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer for whom letrozole therapy is deemed appropriate: An expanded access study in Australia and India.

AIM: Palbociclib was approved in the United States in 2015 to treat estrogen receptor-positive/human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC). This study evaluated outcomes and safety in patients treated with palbociclib in Australia and India with hormone receptor-positive (HR+)/HER2- ABC before palbociclib became commercially available. METHODS: Postmenopausal women (≥18 years) with HR+/HER2- ABC who were appropriate candidates for letrozole therapy received palbociclib 125 mg once daily for 21 days followed by 7 days off, and letrozole 2.5 mg once daily (continuous). Safety, tumor response, and patient-reported outcomes (Australian cohort) were evaluated. RESULTS: In total, 252 patients received palbociclib plus letrozole (Australia, n = 152; India, n = 100). More patients in the Australian versus Indian cohort had received prior chemotherapy (advanced/metastatic setting: 45.9% vs. 32.0%), endocrine therapy (advanced/metastatic setting: 63.2% vs. 54.3%), and advanced/metastatic therapies (61.8% vs. 31.0%). The most frequently reported all-grade palbociclib-related treatment-emergent adverse events were neutropenia (66.7%), fatigue (35.3%), and stomatitis (26.6%); grade 3/4 neutropenia was reported as palbociclib-related in 62.7% of patients. Febrile neutropenia was reported in six patients (2.4%). Eight patients (3.2%) discontinued because of an adverse event. The objective response rate was 19.4% (95% CI, 14.7%-24.9%) overall and 2.3% in Australian patients with ≥2 lines of prior therapy for metastatic disease. Patient-reported quality of life scores were maintained throughout the study. CONCLUSIONS: In an expanded access setting in Australia and India, palbociclib plus letrozole was well tolerated in patients with HR+/HER2- ABC, with a safety profile consistent with previous reports.

Efficacy and safety of palbociclib in patients with estrogen receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer with preexisting conditions: A post hoc analysis of PALOMA-2.

OBJECTIVE: In the PALOMA-2 trial, palbociclib in combination with letrozole prolonged progression-free survival (PFS) and exhibited an acceptable safety profile in patients with estrogen receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer (ABC). This post hoc analysis of PALOMA-2 evaluated the efficacy and safety of palbociclib plus letrozole in patients with preexisting conditions grouped by Medical Dictionary for Regulatory Activities (MedDRA) System Organ Class (SOC). METHODS: Postmenopausal patients without prior treatment for ABC were randomized 2:1 to receive palbociclib (125 mg/d on a 3 weeks on/1 week off schedule) plus letrozole (2.5 mg/d, continuous) or placebo plus letrozole. Patients were grouped by the following MedDRA SOC preexisting conditions: gastrointestinal, musculoskeletal, metabolic, and vascular/cardiac. Median PFS was estimated by the Kaplan-Meier method, and treatment emergent adverse events (AEs) were compared between treatment arms within each preexisting condition subgroup. RESULTS: At baseline, 276 (41.4 %) patients had preexisting gastrointestinal disorders, 390 (58.6 %) had musculoskeletal disorders, 259 (38.9 %) had metabolic disorders, and 382 (57.4 %) had vascular/cardiac disorders. Baseline characteristics were similar between subgroups and between each arm within subgroups. Regardless of baseline preexisting condition, palbociclib plus letrozole prolonged PFS compared with placebo plus letrozole. Treatment-emergent AEs associated with palbociclib plus letrozole and dose modifications due to AEs were similar across preexisting condition subgroups. CONCLUSION: This post hoc analysis of PALOMA-2 demonstrated a favorable effect of palbociclib on PFS and a safety profile consistent with previous observations, regardless of underlying preexisting condition. Pfizer Inc (NCT01740427).

Overall survival results from the randomized phase 2 study of palbociclib in combination with letrozole versus letrozole alone for first-line treatment of ER+/HER2- advanced breast cancer (PALOMA-1, TRIO-18).

PURPOSE: Palbociclib is a cyclin-dependent kinase 4/6 (CDK4/6) inhibitor, approved in combination with endocrine therapy for the treatment of women and men with hormone receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer (HR+/HER2- ABC). In the phase 2, open-label, PALOMA-1 trial, palbociclib plus letrozole significantly prolonged progression-free survival (PFS) versus letrozole alone (hazard ratio, 0.488; 95% CI 0.319‒0.748; P = 0.0004; median PFS, 20.2 vs 10.2 months, respectively) in postmenopausal women with estrogen receptor-positive (ER+)/HER2- ABC. Here, we present the final overall survival (OS) and updated safety results. METHODS: Postmenopausal women with ER+/HER2- ABC were randomized 1:1 to receive either palbociclib (125 mg/day, 3/1 schedule) plus letrozole (2.5 mg/day, continuous) or letrozole alone (2.5 mg/day, continuous). The primary endpoint was investigator-assessed PFS; secondary endpoints included OS and safety. RESULTS: A total of 165 patients were randomized. At the data cutoff date of December 30, 2016 (median duration of follow-up, 64.7 months), the stratified hazard ratio for OS was 0.897 (95% CI 0.623-1.294; P = 0.281); median OS in the palbociclib plus letrozole and letrozole alone arms was 37.5 and 34.5 months, respectively. The median time from randomization to first subsequent chemotherapy use was longer with palbociclib plus letrozole than letrozole alone (26.7 and 17.7 months, respectively). The most frequently reported adverse event in the palbociclib plus letrozole arm was neutropenia (any grade, 75%; grade 3 or 4, 59%). CONCLUSIONS: Palbociclib plus letrozole treatment led to a numerical but not statistically significant improvement in median OS. Pfizer Inc (NCT00721409).

Palbociclib plus endocrine therapy in older women with HR+/HER2- advanced breast cancer: a pooled analysis of randomised PALOMA clinical studies.

AIM: Because incidence of breast cancer and comorbidities increase with age, it is important to determine treatment benefit in elderly patients. We evaluated outcomes with palbociclib plus endocrine therapy in patients aged ≥65 years. METHODS: Data were pooled from three randomised studies (NCT00721409, NCT01740427 and NCT01942135) of women with HR+/HER2- advanced breast cancer (ABC). In PALOMA-1 (open-label) and PALOMA-2 (double-blind, placebo-controlled), treatment-naïve patients received palbociclib plus letrozole or letrozole alone. In PALOMA-3 (double-blind, placebo-controlled), patients with endocrine-resistant disease received palbociclib plus fulvestrant or fulvestrant alone. RESULTS: Among 528 patients treated with palbociclib plus letrozole and 347 treated with palbociclib plus fulvestrant, 218 (41.3%) and 86 (24.8%), respectively, were aged ≥65 years. Versus endocrine therapy alone, median progression-free survival was significantly improved in patients aged 65-74 years (hazard ratio [HR], 0.66; 95% confidence interval [CI], 0.45-0.97; P = 0.016) and ≥75 years (HR, 0.31; 95% CI, 0.16-0.61; P<0.001) receiving palbociclib plus letrozole and in patients aged 65-74 years (HR, 0.27; 95% CI, 0.16-0.48; P<0.001) receiving palbociclib plus fulvestrant; few patients aged ≥75 years received palbociclib plus fulvestrant (HR, 0.59; 95% CI, 0.19-1.8; P = 0.18). Patient-reported functioning and quality of life was maintained. No clinically relevant differences in palbociclib exposure were observed between age groups. Although myelosuppression was more common among patients aged ≥75 years, incidence of grade ≥III myelosuppression was similar across age groups, and febrile neutropenia was uncommon (≤2.4%); no new safety concerns were identified in older patients. CONCLUSIONS: Palbociclib plus endocrine therapy is an effective, well-tolerated treatment for older patients with ABC.

Efficacy and safety of palbociclib in combination with letrozole as first-line treatment of ER-positive, HER2-negative, advanced breast cancer: expanded analyses of subgroups from the randomized pivotal trial PALOMA-1/TRIO-18.

BACKGROUND: Palbociclib is an oral small-molecule inhibitor of cyclin-dependent kinases 4 and 6. In the randomized, open-label, phase II PALOMA-1/TRIO-18 trial, palbociclib in combination with letrozole improved progression-free survival (PFS) compared with letrozole alone as first-line treatment of estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative, advanced breast cancer (20.2 months versus 10.2 months; hazard ratio (HR) = 0.488, 95 % confidence interval (CI) 0.319-0.748; one-sided p = 0.0004). Grade 3-4 neutropenia was the most common adverse event (AE) in the palbociclib + letrozole arm. We now present efficacy and safety analyses based on several specific patient and tumor characteristics, and present in detail the clinical patterns of neutropenia observed in the palbociclib + letrozole arm of the overall safety population. METHODS: Postmenopausal women (n = 165) with ER+, HER2-negative, advanced breast cancer who had not received any systemic treatment for their advanced disease were randomized 1:1 to receive either palbociclib in combination with letrozole or letrozole alone. Treatment continued until disease progression, unacceptable toxicity, consent withdrawal, or death. The primary endpoint was PFS. We now analyze the difference in PFS for the treatment populations by subgroups, including age, histological type, history of prior neoadjuvant/adjuvant systemic treatment, and sites of distant metastasis, using the Kaplan-Meier method. HR and 95 % CI are derived from a Cox proportional hazards regression model. RESULTS: A clinically meaningful improvement in median PFS and clinical benefit response (CBR) rate was seen with palbociclib + letrozole in every subgroup evaluated. Grade 3-4 neutropenia was the most common AE with palbociclib + letrozole in all subgroups. Analysis of the frequency of neutropenia by grade during the first six cycles of treatment showed that there was a downward trend in Grade 3-4 neutropenia over time. Among those who experienced Grade 3-4 neutropenia, 71.7 % had no overlapping infections of any grade and none had overlapping Grade 3-4 infections. CONCLUSION: The magnitude of clinical benefit seen with the addition of palbociclib to letrozole in improving both median PFS and CBR rate is consistent in nearly all subgroups analyzed, and consistent with that seen in the overall study population. The safety profile of the combination treatment in all subgroups was also comparable to that in the overall safety population of the study.

Phase 1/2 study of cyclin-dependent kinase (CDK)4/6 inhibitor palbociclib (PD-0332991) with bortezomib and dexamethasone in relapsed/refractory multiple myeloma.

This phase 1/2 study was the first to evaluate the safety and efficacy of the cyclin-dependent kinase (CDK) 4/6-specific inhibitor palbociclib (PD-0332991) in sequential combination with bortezomib and dexamethasone in relapsed/refractory multiple myeloma. The recommended phase 2 dose was palbociclib 100 mg orally once daily on days 1-12 of a 21-day cycle with bortezomib 1.0 mg/m2 (intravenous) and dexamethasone 20 mg (orally 30 min pre-bortezomib dosing) on days 8 and 11 (early G1 arrest) and days 15 and 18 (cell cycle resumed). Dose-limiting toxicities were primarily cytopenias; most other treatment-related adverse events were grade≤3. At a bortezomib dose lower than that in other combination therapy studies, antitumor activity was observed (phase 1). In phase 2, objective responses were achieved in 5 (20%) patients; 11 (44%) achieved stable disease. Biomarker and pharmacodynamic assessments demonstrated that palbociclib inhibited CDK4/6 and the cell cycle initially in most patients.

The cyclin-dependent kinase 4/6 inhibitor palbociclib in combination with letrozole versus letrozole alone as first-line treatment of oestrogen receptor-positive, HER2-negative, advanced breast cancer (PALOMA-1/TRIO-18): a randomised phase 2 study.

BACKGROUND: Palbociclib (PD-0332991) is an oral, small-molecule inhibitor of cyclin-dependent kinases (CDKs) 4 and 6 with preclinical evidence of growth-inhibitory activity in oestrogen receptor-positive breast cancer cells and synergy with anti-oestrogens. We aimed to assess the safety and efficacy of palbociclib in combination with letrozole as first-line treatment of patients with advanced, oestrogen receptor-positive, HER2-negative breast cancer. METHODS: In this open-label, randomised phase 2 study, postmenopausal women with advanced oestrogen receptor-positive and HER2-negative breast cancer who had not received any systemic treatment for their advanced disease were eligible to participate. Patients were enrolled in two separate cohorts that accrued sequentially: in cohort 1, patients were enrolled on the basis of their oestrogen receptor-positive and HER2-negative biomarker status alone, whereas in cohort 2 they were also required to have cancers with amplification of cyclin D1 (CCND1), loss of p16 (INK4A or CDKN2A), or both. In both cohorts, patients were randomly assigned 1:1 via an interactive web-based randomisation system, stratified by disease site and disease-free interval, to receive continuous oral letrozole 2.5 mg daily or continuous oral letrozole 2.5 mg daily plus oral palbociclib 125 mg, given once daily for 3 weeks followed by 1 week off over 28-day cycles. The primary endpoint was investigator-assessed progression-free survival in the intention-to-treat population. Accrual to cohort 2 was stopped after an unplanned interim analysis of cohort 1 and the statistical analysis plan for the primary endpoint was amended to a combined analysis of cohorts 1 and 2 (instead of cohort 2 alone). The study is ongoing but closed to accrual; these are the results of the final analysis of progression-free survival. The study is registered with the ClinicalTrials.gov, number NCT00721409. FINDINGS: Between Dec 22, 2009, and May 12, 2012, we randomly assigned 165 patients, 84 to palbociclib plus letrozole and 81 to letrozole alone. At the time of the final analysis for progression-free survival (median follow-up 29.6 months [95% CI 27.9-36.0] for the palbociclib plus letrozole group and 27.9 months [25.5-31.1] for the letrozole group), 41 progression-free survival events had occurred in the palbociclib plus letrozole group and 59 in the letrozole group. Median progression-free survival was 10.2 months (95% CI 5.7-12.6) for the letrozole group and 20.2 months (13.8-27.5) for the palbociclib plus letrozole group (HR 0.488, 95% CI 0.319-0.748; one-sided p=0.0004). In cohort 1 (n=66), median progression-free survival was 5.7 months (2.6-10.5) for the letrozole group and 26.1 months (11.2-not estimable) for the palbociclib plus letrozole group (HR 0.299, 0.156-0.572; one-sided p<0.0001); in cohort 2 (n=99), median progression-free survival was 11.1 months (7.1-16.4) for the letrozole group and 18.1 months (13.1-27.5) for the palbociclib plus letrozole group (HR 0.508, 0.303-0.853; one-sided p=0.0046). Grade 3-4 neutropenia was reported in 45 (54%) of 83 patients in the palbociclib plus letrozole group versus one (1%) of 77 patients in the letrozole group, leucopenia in 16 (19%) versus none, and fatigue in four (4%) versus one (1%). Serious adverse events that occurred in more than one patient in the palbociclib plus letrozole group were pulmonary embolism (three [4%] patients), back pain (two [2%]), and diarrhoea (two [2%]). No cases of febrile neutropenia or neutropenia-related infections were reported during the study. 11 (13%) patients in the palbociclib plus letrozole group and two (2%) in the letrozole group discontinued the study because of adverse events. INTERPRETATION: The addition of palbociclib to letrozole in this phase 2 study significantly improved progression-free survival in women with advanced oestrogen receptor-positive and HER2-negative breast cancer. A phase 3 trial is currently underway. FUNDING: Pfizer.

Circulating proteins as potential biomarkers of sunitinib and interferon-α efficacy in treatment-naïve patients with metastatic renal cell carcinoma.

PURPOSE: We investigated potential biomarkers of efficacy in a phase III trial of sunitinib versus interferon-alpha (IFN-α), first-line in metastatic renal cell carcinoma (mRCC), by analyzing plasma levels of vascular endothelial growth factor (VEGF)-A, VEGF-C, soluble VEGF receptor-3 (sVEGFR-3) and interleukin (IL)-8. METHODS: Seven hundred and fifty mRCC patients were randomized to oral sunitinib 50 mg/day in repeated cycles of a 4-week on/2-week off schedule or IFN-α 9 million units subcutaneously thrice weekly. Plasma samples collected from a subset of 63 patients on days 1 and 28 of cycles 1-4 and at end of treatment were analyzed by ELISA. RESULTS: Baseline characteristics of biomarker-evaluated patients in sunitinib (N = 33) and IFN-α (N = 30) arms were comparable to their respective intent-to-treat populations. By univariate Cox regression analysis, low baseline soluble protein levels were associated with lower risk of progression/death (all P < 0.05): in both treatment arms, baseline VEGF-A and IL-8 were associated with overall survival (OS) and baseline VEGF-C with progression-free survival (PFS); in the sunitinib arm, baseline VEGF-A was associated with PFS and baseline sVEGFR-3 with PFS and OS; in the IFN-α arm, baseline IL-8 was associated with PFS. In multivariate analysis, baseline sVEGFR-3 and IL-8 remained independent predictors of OS in the sunitinib arm, while no independent predictors of outcome remained in the IFN-α arm. Pharmacodynamic changes were not associated with PFS or OS for any plasma protein investigated. CONCLUSIONS: Our findings suggest that, in mRCC, baseline VEGF-A and IL-8 may have prognostic value, while baseline sVEGFR-3 may predict sunitinib efficacy.

Analyzing the pivotal trial that compared sunitinib and IFN-α in renal cell carcinoma, using a method that assesses tumor regression and growth.

PURPOSE: We applied a method that analyzes tumor response, quantifying the rates of tumor growth (g) and regression (d), using tumor measurements obtained while patients receive therapy. We used data from the phase III trial comparing sunitinib and IFN-α in metastatic renal cell carcinoma (mRCC) patients. METHODS: The analysis used an equation that extracts d and g. RESULTS: For sunitinib, overall survival (OS) was strongly correlated with log g (Rsq = 0.44, P < 0.0001); much less with log d (Rsq = 0.04; P = 0.0002). The median g of tumors in these patients (0.00082 per days; log g = -3.09) was about half that (P < 0.001) of tumors in patients receiving IFN-α (0.0015 per day; log g = -2.81). With IFN-α, the OS/log g correlation (Rsq = 0.14) was weaker. Values of g from measurements obtained by study investigators or central review were highly correlated (Rsq = 0.80). No advantage resulted in including data from central review in regressions. Furthermore, g can be estimated accurately four months before treatment discontinuation. Extrapolating g in a model that incorporates survival generates the hypothesis that g increased after discontinuation of sunitinib but did not accelerate. CONCLUSIONS: In patients with mRCC, sunitinib reduced tumor growth rate, g, more than did IFN-α. Correlating g with OS confirms earlier analyses suggesting g may be an important clinical trial endpoint, to be explored prospectively and in individual patients.

Phase II study of sunitinib as maintenance therapy in patients with locally advanced or metastatic non-small cell lung cancer.

This open-label, phase II study evaluated the antitumor activity and safety of sunitinib monotherapy as maintenance treatment following first-line chemotherapy in patients with locally advanced or metastatic non-small cell lung cancer (NSCLC). Following treatment with standard doublet chemotherapy (paclitaxel and carboplatin), patients received oral sunitinib (starting dose 50mg/day) in 6-week cycles (Schedule 4/2: 4 weeks on treatment, 2 weeks off treatment) until disease progression, unacceptable toxicity or withdrawal of consent. The primary endpoint was probability of survival at 1 year ≥55%. Of 84 patients who received first-line chemotherapy, 66 (79%) received sunitinib maintenance therapy (median sunitinib cycles started: 2 [range 1-20]). Probability of survival at 1 year was 40.5% (95% confidence interval [CI]: 29.8, 51.0). Median overall survival was 10.4 months (95% CI: 8.0, 12.2). The objective response rate was 27.4% (95% CI: 18.2, 38.2). The most frequently reported all-causality adverse events of any grade during sunitinib maintenance therapy were fatigue/asthenia (55%), diarrhea (36%), and nausea (32%). These data suggest that maintenance therapy may have value in NSCLC, although the primary endpoint of the study was not met.

Sunitinib in combination with paclitaxel plus carboplatin in patients with advanced solid tumors: phase I study results.

PURPOSE: To evaluate the maximum tolerated dose (MTD), safety, and antitumor activity of sunitinib combined with paclitaxel and carboplatin. METHODS: Successive cohorts of patients with advanced solid tumors received oral sunitinib (25, 37.5, or 50 mg) for 2 consecutive weeks of a 3-week cycle (Schedule 2/1) or as a continuous daily dose for 3-week cycles (CDD schedule) in combination with paclitaxel (175-200 mg/m(2)) plus carboplatin (AUC 6 mg min/ml) on day one of each of 4 cycles. Dose-limiting toxicities (DLTs) and adverse events (AEs) were evaluated to determine the MTD. Efficacy parameters were analyzed in patients with measurable disease. RESULTS: Forty-three patients were enrolled (n = 25 Schedule 2/1; n = 18 CDD schedule). Across all doses, 6 DLTs were observed [grade 4 papilledema, grade 5 GI hemorrhage, grade 3 neutropenic infection, and grade 4 thrombocytopenia (n = 3)]. The MTD for Schedule 2/1 was sunitinib 25 mg plus paclitaxel 175 mg/m(2) and carboplatin AUC 6 mg min/ml. The MTD was not determined for the CDD schedule. Treatment-related AEs included neutropenia (77%), thrombocytopenia (56%), and fatigue (47%). Of 38 evaluable patients, 4 (11%) had partial responses and 12 (32%) had stable disease. PK data indicated an increase in maximum and total plasma exposures to sunitinib and its active metabolite when given with paclitaxel and carboplatin compared with sunitinib monotherapy. CONCLUSIONS: Myelosuppression resulting in prolonged dose delays and frequent interruptions was observed, suggesting that this treatment combination is not feasible in the general cancer population.

Phase I/II trial of sunitinib plus gefitinib in patients with metastatic renal cell carcinoma.

OBJECTIVES: Sunitinib is an oral, multitargeted tyrosine kinase inhibitor of vascular endothelial growth factor and platelet-derived growth factor receptors with proven clinical benefit in patients with metastatic renal cell carcinoma (RCC). This phase I/II study investigated sunitinib in combination with an epidermal growth factor receptor inhibitor, gefitinib, in patients with metastatic RCC. METHODS: In phase I, patients received sunitinib 37.5 or 50 mg in 6-week cycles (4 weeks on treatment, 2 off) plus gefitinib 250 mg, both once daily, to determine the sunitinib maximum tolerated dose (MTD). Pharmacokinetics was assessed for both drugs. In phase II, patients received sunitinib MTD plus gefitinib to evaluate the safety and antitumor activity of this combination. RESULTS: Forty-two patients were enrolled: 11 in phase I, and 31 in phase II. In phase I, 2 dose-limiting toxicities were observed with sunitinib 50 mg (grade 2 left ventricular ejection fraction decline and grade 3 fatigue), and 37.5 mg was declared the MTD. Thirteen patients treated at the MTD achieved a partial response (objective response rate: 37%; 95% confidence interval, 22-55) and 12 (34%) had stable disease. Median progression-free survival was 11 months (95% confidence interval, 6-17). The most commonly reported grade 3/4 treatment-related adverse event was diarrhea (14%), the only grade 3/4 adverse event to occur in >2 patients. Pharmacokinetic analyses did not indicate any drug-drug interactions. CONCLUSIONS: In metastatic RCC, sunitinib plus gefitinib demonstrated comparable efficacy to sunitinib monotherapy with an acceptable safety profile. Dosing, pharmacokinetic profile, and safety support study of sunitinib plus an epidermal growth factor receptor inhibitor in other tumor types.