Efficacy and safety of a four-drug, quarter-dose treatment for hypertension: the QUARTET USA randomized trial.

New approaches are needed to lower blood pressure (BP) given persistently low control rates. QUARTET USA sought to evaluate the effect of four-drug, quarter-dose BP lowering combination in patients with hypertension. QUARTET USA was a randomized (1:1), double-blinded trial conducted in federally qualified health centers among adults with hypertension. Participants received either a quadpill of candesartan 2 mg, amlodipine 1.25 mg, indapamide 0.625 mg, and bisoprolol 2.5 mg or candesartan 8 mg for 12 weeks. If BP was >130/>80 mm Hg at 6 weeks in either arm, then participants received open label add-on amlodipine 5 mg. The primary outcome was mean change in systolic blood pressure (SBP) at 12 weeks, controlling for baseline BP. Secondary outcomes included mean change in diastolic blood pressure (DBP), and safety included serious adverse events, relevant adverse drug effects, and electrolyte abnormalities. Among 62 participants randomized between August 2019-May 2022 (n = 32 intervention, n = 30 control), mean (SD) age was 52 (11.5) years, 45% were female, 73% identified as Hispanic, and 18% identified as Black. Baseline mean (SD) SBP was 138.1 (11.2) mmHg, and baseline mean (SD) DBP was 84.3 (10.5) mmHg. In a modified intention-to-treat analysis, there was no significant difference in SBP (-4.8 mm Hg [95% CI: -10.8, 1.3, p = 0.123] and a -4.9 mmHg (95% CI: -8.6, -1.3, p = 0.009) greater mean DBP change in the intervention arm compared with the control arm at 12 weeks. Adverse events did not differ significantly between arms. The quadpill had a similar SBP and greater DBP lowering effect compared with candesartan 8 mg. Trial registration number: NCT03640312.

Process Evaluation of a Double-Blind Randomized Controlled Trial to Assess the Efficacy and Safety of a Quadruple Ultra-Low-Dose Treatment for Hypertension Within a Federally Qualified Health Center Network (QUARTET USA).

BACKGROUND: This convergent parallel-design mixed-methods process evaluation of the QUARTET USA (Quadruple Ultra-Low-Dose Treatment for Hypertension USA) clinical trial (NCT03640312) explores patient and health care professional perceptions about the use of low-dose quadruple therapy (LDQT) as a novel strategy for hypertension management. METHODS AND RESULTS: A survey of all 62 patients enrolled in the QUARTET USA trial was conducted. A subsample of 13 patients and 11 health care professionals, recruited via purposive sampling, took part in semistructured interviews. At enrollment, 68% of participants (mean [SD] age, 51.7 [11.5] years; 56% self-identified as Hispanic: Mexican ethnicity, 16% as Hispanic: other ethnicity, 16% as Black race, 8% as White race, and 1.6% as South Asian race) reported that their current health depended on blood pressure medications, and 48% were concerned about blood pressure medications. At trial completion, 80% were satisfied with LDQT, 96% were certain the benefits of taking LDQT outweighed the disadvantages, and 96% reported that LDQT was convenient to take. Both patients and health care professionals found LDQT acceptable because it reduced patients' perceived pill burden and facilitated medication adherence. Health care professionals stated that a perceived limitation of LDQT was the inability to titrate doses. Steps to facilitate LDQT implementation include introducing stepped-care combinations and treatment protocols, inclusion in clinical practice guidelines, and eliminating patient cost barriers. CONCLUSIONS: LDQT was an acceptable strategy for hypertension treatment among patients and health care professionals involved in the QUARTET USA clinical trial. Although LDQT was generally perceived as beneficial for maintaining patients' blood pressure control and facilitating adherence, some clinicians perceived limitations in titration inflexibility, adverse effects, and costs. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03640312.

Efficacy and safety of a quadruple ultra-low-dose treatment for hypertension (QUARTET USA): Rationale and design for a randomized controlled trial.

BACKGROUND: Over half of patients with elevated blood pressure require multi-drug treatment to achieve blood pressure control. However, multi-drug treatment may lead to lower adherence and more adverse drug effects compared with monotherapy. OBJECTIVE: The Quadruple Ultra-low-dose Treatment for Hypertension (QUARTET) USA trial was designed to evaluate whether initiating treatment with ultra-low-dose quadruple-combination therapy will lower office blood pressure more effectively, and with fewer side effects, compared with initiating standard dose monotherapy in treatment naive patients with SBP < 180 and DBP < 110 mm Hg and patients on monotherapy with SBP < 160 and DBP < 100 mm Hg. METHODS/DESIGN: QUARTET USA was a prospective, randomized, double-blind trial (ClinicalTrials.gov NCT03640312) conducted in federally qualified health centers in a large city in the US. Patients were randomly assigned (1:1) to either ultra-low-dose quadruple combination therapy or standard dose monotherapy. The primary outcome was mean change from baseline in office systolic blood pressure at 12-weeks, adjusted for baseline values. Secondary outcomes included measures of blood pressure change and variability, medication adherence, and health related quality of life. Safety outcomes included occurrence of serious adverse events, relevant adverse drug effects, and electrolyte abnormalities. A process evaluation aimed to understand provider experiences of implementation and participant experiences around side effects, adherence, and trust with clinical care. DISCUSSION: QUARTET USA was designed to evaluate whether a novel approach to blood pressure control would lower office blood pressure more effectively, and with fewer side effects, compared with standard dose monotherapy. QUARTET USA was conducted within a network of federally qualified healthcare centers with the aim of generating information on the safety and efficacy of ultra-low-dose quadruple-combination therapy in diverse groups that experience a high burden of hypertension.

Recurrent horizontal transfer identifies mitochondrial positive selection in a transmissible cancer.

Autonomous replication and segregation of mitochondrial DNA (mtDNA) creates the potential for evolutionary conflict driven by emergence of haplotypes under positive selection for 'selfish' traits, such as replicative advantage. However, few cases of this phenomenon arising within natural populations have been described. Here, we survey the frequency of mtDNA horizontal transfer within the canine transmissible venereal tumour (CTVT), a contagious cancer clone that occasionally acquires mtDNA from its hosts. Remarkably, one canine mtDNA haplotype, A1d1a, has repeatedly and recently colonised CTVT cells, recurrently replacing incumbent CTVT haplotypes. An A1d1a control region polymorphism predicted to influence transcription is fixed in the products of an A1d1a recombination event and occurs somatically on other CTVT mtDNA backgrounds. We present a model whereby 'selfish' positive selection acting on a regulatory variant drives repeated fixation of A1d1a within CTVT cells.

Somatic evolution and global expansion of an ancient transmissible cancer lineage.

The canine transmissible venereal tumor (CTVT) is a cancer lineage that arose several millennia ago and survives by "metastasizing" between hosts through cell transfer. The somatic mutations in this cancer record its phylogeography and evolutionary history. We constructed a time-resolved phylogeny from 546 CTVT exomes and describe the lineage's worldwide expansion. Examining variation in mutational exposure, we identify a highly context-specific mutational process that operated early in the cancer's evolution but subsequently vanished, correlate ultraviolet-light mutagenesis with tumor latitude, and describe tumors with heritable hyperactivity of an endogenous mutational process. CTVT displays little evidence of ongoing positive selection, and negative selection is detectable only in essential genes. We illustrate how long-lived clonal organisms capture changing mutagenic environments, and reveal that neutral genetic drift is the dominant feature of long-term cancer evolution.

Mitochondrial genetic diversity, selection and recombination in a canine transmissible cancer.

Canine transmissible venereal tumour (CTVT) is a clonally transmissible cancer that originated approximately 11,000 years ago and affects dogs worldwide. Despite the clonal origin of the CTVT nuclear genome, CTVT mitochondrial genomes (mtDNAs) have been acquired by periodic capture from transient hosts. We sequenced 449 complete mtDNAs from a global population of CTVTs, and show that mtDNA horizontal transfer has occurred at least five times, delineating five tumour clades whose distributions track two millennia of dog global migration. Negative selection has operated to prevent accumulation of deleterious mutations in captured mtDNA, and recombination has caused occasional mtDNA re-assortment. These findings implicate functional mtDNA as a driver of CTVT global metastatic spread, further highlighting the important role of mtDNA in cancer evolution.