A mixed-methods study of cyclin-dependent kinase 4 and 6 inhibitor symptom burden and quality of life among metastatic breast cancer patients and providers.

BACKGROUND: Cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor targeted therapies dramatically improve survival outcomes for metastatic breast cancer (MBC), but they are associated with significant symptom burden that can impact patients' health-related quality of life (HRQOL) and treatment outcomes. This study is the first to describe CDK4/6 inhibitor symptoms from the lived perspectives of MBC patients taking CDK4/6 inhibitors and healthcare providers involved in MBC care. This study also explored patients' symptom management and HRQOL concerns, and gathered feedback about developing supportive interventions for MBC. METHODS: MBC patients taking CDK4/6 inhibitors (N = 20) and MBC healthcare providers (N = 12) participated in semi-structured interviews that were analyzed for qualitative themes. MBC patients completed surveys about HRQOL, symptoms, and unmet needs. RESULTS: Patient and provider perceptions of CDK4/6 inhibitor symptoms did not align with patients perceiving symptoms as more burdensome. Patients reported that supportive resources (e.g., support groups, blogs) that are not specific to MBC do not adequately meet their needs. Patients and providers were enthusiastic about developing supportive interventions specifically for MBC and offered considerations for designing such interventions. CONCLUSIONS: Findings highlight differences in perceptions of CDK4/6 inhibitor symptom burden between MBC patients and providers. Results will inform the development of supportive interventions to assist MBC patients in managing CDK4/6 inhibitor symptom burden and maintaining HRQOL. Such interventions could also improve treatment outcomes.

Effect of food on the bioavailability of palbociclib.

PURPOSE: This phase I study estimated the effect of food on bioavailability of palbociclib (IBRANCE®), and a selective inhibitor of cyclin-dependent kinase 4/6 approved for oncology indications has pH-dependent solubility and high permeability. METHODS: In this randomized, four-sequence, four-period crossover study, 28 healthy volunteers received a single 125-mg dose of palbociclib (free-base capsule) following an overnight fast or (1) after a high-fat/-calorie meal, (2) after a low-fat/-calorie meal, and (3) between two moderate-fat/standard-calorie meals. Pharmacokinetic samples were collected predose and serially ≤144 h postdose; palbociclib concentrations were measured using validated high-performance liquid chromatography tandem mass spectrometry. Pharmacokinetic data were analyzed using a noncompartmental approach based on a mixed-effects model. RESULTS: Median time to maximum concentration was 8 h for all conditions. Exposure (AUCinf and C max) increased slightly in the fed versus fasted conditions; ratios (90% CIs) of the adjusted geometric mean relative to the fasted condition ranged from 111.8 (104.3-119.9%) to 120.6% (112.6-129.1%) for AUCinf and from 124.0 (108.4-141.9%) to 137.8% (120.6-157.5%) for C max due mainly to three subjects with significantly lower exposure (low liers) in the fasted condition. Pharmacokinetic variability was reduced in the fed (AUCinf, 23-27%; C max, 21-24%) versus fasted (AUCinf, 39%; C max, 73%) conditions. In a supplemental analysis excluding the three low liers, food intake did not affect palbociclib exposure. CONCLUSIONS: Food intake modestly increased palbociclib exposure while greatly reducing pharmacokinetic variability. For subjects with normal absorption, food intake did not affect palbociclib exposure. Thus, palbociclib should be administered with food. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01904747.

A phase II, single-arm, open-label, multicenter study to evaluate the efficacy and safety of P276-00, a cyclin-dependent kinase inhibitor, in patients with relapsed or refractory mantle cell lymphoma.

INTRODUCTION: Overexpression of cyclin D1 is a hallmark feature of mantle cell lymphoma (MCL). Many of the oncogenic effects of cyclin D1 are mediated through cyclin-dependent kinases (CDKs). P276-00 is a potent small molecule inhibitor of CDK4-D1, CDK1-B, and CDK9-T, with promising activity in preclinical models. In phase I studies of P276-00 in patients with refractory solid neoplasms, it was well-tolerated with a mild trend toward single-agent efficacy. PATIENTS AND METHODS: A phase II study of P276-00 was conducted in patients with relapsed or refractory MCL at the recommended dose of 185 mg/m(2)/day from days 1 to 5 of a 21-day cycle. Thirteen patients were enrolled in the present study. RESULTS: Of the 13 patients, 11 experienced disease progression, 1 patient was withdrawn because of an adverse event (AE), and 1 patient died. Also, 11 patients (84.6%) experienced a treatment-emergent AE deemed related to P276-00. Of the 13 patients, 9 (69.2%) received ≥ 2 cycles of treatment, which was the predefined threshold to be evaluable for efficacy. Treatment was discontinued early in 2 patients because of AEs (1 of which was attributed to P276-00 administration) and in 2 patients because of disease progression. Finally, 2 patients experienced stable disease for an estimated median duration of 60.5 days (range, 58-63 days). The estimated median time to progression for the predefined efficacy population was 43 days (range, 38-58 days). CONCLUSION: Given the results observed in the present study, if evaluation of CDK inhibition in MCL continues, it should be considered earlier in the disease course or as a part of combination strategies for relapsed or refractory disease.