Shen, Shu‐En

Background/Objectives. Decades of research have failed to uncover effective approaches to prevent chemotherapy-induced peripheral neuropathy (CIPN), a common side effect of neurotoxic chemotherapy. Increased interest in placebo response as a potentially under-recognized confounder in CIPN trials was recently sparked by the results of a multisite NCI-funded phase II-III CIPN prevention study of duloxetine, a promising serotonin–norepinephrine reuptake inhibitor that enhances pain-inhibitory mechanisms within the central nervous system. Study findings revealed high and nearly equivalent response rates in three randomized treatment groups—little to no CIPN was reported by 65.2%, 66.0%, and 68.0% of study participants who received duloxetine 30 mg, 60 mg, or placebo treatment, respectively. Methods. We performed a meta-analysis of placebo response rates from seven randomized, double-blinded, placebo-controlled trials conducted over the past 20 years and comprising 191 placebo participants that were specifically testing interventions for oxaliplatin- and paclitaxel-induced peripheral neuropathy and that serially collected patient responses on the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire for Chemotherapy-Induced Neuropathy questionnaire. Additionally, we sought to identify trial- and patient-specific factors that predicted higher placebo response rates from a participant-level pooled analysis. Results. The placebo response rate was 10.0% [95% CI: 5.8%, 16.6%] when response was defined more conservatively as patients reporting no neuropathy at all. When the placebo response was defined more broadly based on patients reporting no or a little neuropathy, the placebo response rate was higher (39.6% [95% CI: 27.4%, 53.2%]). Male participants, receipt of oxaliplatin, and a 2:1 randomization ratio favoring the intervention arm were individually associated with a higher placebo response. Conclusions. High placebo response rates can threaten scientific progress toward identifying effective treatments for cancer treatment-associated side effects, like CIPN. Careful attention to study design factors, participant eligibility, and patient and research staff expectations may help to minimize placebo response rates in future CIPN intervention studies.

ImportanceThere is substantial interest in capturing cancer treatment tolerability from the patient’s perspective using patient-reported outcomes (PROs).ObjectiveTo examine whether a PRO question, item 5 from the Functional Assessment of Cancer Therapy-General General Physical Wellbeing Scale (GP5), was associated with early treatment discontinuation (ETD) due to adverse events.Design, Setting, and ParticipantsThis prospective survey study was conducted from February to April 2023. Among participants in the ECOG-ACRIN E1A11 trial (a phase 3, parallel design trial conducted between 2013 and 2019), patients with newly diagnosed multiple myeloma were randomized to receive bortezomib (VRd) or carfilzomib (KRd) plus lenalidomide and dexamethasone as induction therapy. The GP5 item was administered at baseline (pretreatment) and at 1 month, 2.8 months, and 5.5 months postbaseline. Eligible participants included patients with newly diagnosed multiple myeloma treated at community oncology practices or academic medical centers in the US.ExposuresGP5 response options were “very much,” “quite a bit,” “somewhat,” “a little bit,” and “not at all.” Responses at each assessment while undergoing treatment (1 month, 2.8 months, and 5.5 months) were categorized as high adverse event bother (ie, “very much,” and “quite a bit”) and low adverse event bother (ie, “somewhat,” “a little bit,” or “not at all”). In addition, change from baseline to each assessment while undergoing treatment was calculated and categorized as worsening by 1 response category and 2 or more response categories.Main Outcome and MeasureETD due to adverse events (yes vs no) was analyzed using logistic regression adjusting for treatment group, performance status, gender, race, and disease stage.ResultsOf the 1087 participants in the original trial, 1058 (mean [SD] age 64 [9] years; 531 receiving VrD [50.2%]; 527 receiving KRd [49.8%]) responded to item GP5 and were included in the secondary analysis. A small proportion (142 patients [13.4%]) discontinued treatment early due to AEs. For those with high adverse-effect bother, GP5 while undergoing treatment was associated with ETD at 1 month (adjusted odds ratio [aOR], 2.20; 95% CI, 1.25-3.89), 2.8 months (aOR, 3.41; 95% CI, 2.01-5.80), and 5.5 months (aOR, 4.66; 95% CI, 1.69-12.83). Worsening by 2 or more response categories on the GP5 was associated with ETD at 2.8 months (aOR, 3.02; 95% CI, 1.64-5.54) and 5.5 months (aOR, 5.49; 95% CI, 1.45-20.76).Conclusions and RelevanceIn this survey study of the E1A11 trial, worse GP5 response was associated with ETD. These findings suggest that simple assessment of adverse-effect bother while receiving treatment is an efficient way to indicate treatment tolerability and ETD risk.