Circulating tumor DNA guided adjuvant chemotherapy in stage II colon cancer (MEDOCC-CrEATE): study protocol for a trial within a cohort study

BACKGROUND

Accurate detection of patients with minimal residual disease (MRD) after surgery for stage II colon cancer (CC) remains an urgent unmet clinical need to improve selection of patients who might benefit form adjuvant chemotherapy (ACT). Presence of circulating tumor DNA (ctDNA) is indicative for MRD and has high predictive value for recurrent disease. The MEDOCC-CrEATE trial investigates how many stage II CC patients with detectable ctDNA after surgery will accept ACT and whether ACT reduces the risk of recurrence in these patients.

METHODS/DESIGN

MEDOCC-CrEATE follows the 'trial within cohorts' (TwiCs) design. Patients with colorectal cancer (CRC) are included in the Prospective Dutch ColoRectal Cancer cohort (PLCRC) and give informed consent for collection of clinical data, tissue and blood samples, and consent for future randomization. MEDOCC-CrEATE is a subcohort within PLCRC consisting of 1320 stage II CC patients without indication for ACT according to current guidelines, who are randomized 1:1 into an experimental and a control arm. In the experimental arm, post-surgery blood samples and tissue are analyzed for tissue-informed detection of plasma ctDNA, using the PGDx elio™ platform. Patients with detectable ctDNA will be offered ACT consisting of 8 cycles of capecitabine plus oxaliplatin while patients without detectable ctDNA and patients in the control group will standard follow-up according to guideline. The primary endpoint is the proportion of patients receiving ACT when ctDNA is detectable after resection. The main secondary outcome is 2-year recurrence rate (RR), but also includes 5-year RR, disease free survival, overall survival, time to recurrence, quality of life and cost-effectiveness. Data will be analyzed by intention to treat.

DISCUSSION

The MEDOCC-CrEATE trial will provide insight into the willingness of stage II CC patients to be treated with ACT guided by ctDNA biomarker testing and whether ACT will prevent recurrences in a high-risk population. Use of the TwiCs design provides the opportunity to randomize patients before ctDNA measurement, avoiding ethical dilemmas of ctDNA status disclosure in the control group.

TRIAL REGISTRATION

Netherlands Trial Register: NL6281/NTR6455 . Registered 18 May 2017, https://www.trialregister.nl/trial/6281.

Relative dose intensity as a proxy measure of quality and prognosis in adjuvant chemotherapy for breast cancer in daily clinical practice

AIM

Adjuvant chemotherapy treatment of women with breast cancer is frequently complicated by toxic side-effects, resulting in dose reduction and delay. In Dutch guidelines, a relative dose intensity (RDI) of at least 85% is recommended for optimal treatment. The aim was to investigate predictors of low RDI and its effect on prognosis.

METHODS

All patients treated in the St. Antonius Hospital with adjuvant chemotherapy for breast cancer between 2008 and 2013 were included (N = 605). RDI was calculated for each single chemotherapeutic agent and for chemotherapy regimens in total. Incidence and causes of RDI <85% were studied, as well as the effect of RDI on prognosis.

RESULTS

About 10% of 605 patients had RDIs <85%. Predictive factors included age, episodes of febrile neutropenia and grade III or IV hypersensitivity reaction to taxanes. Other adverse events, such as peripheral neuropathy, did not affect RDI. The incidence of febrile neutropenia in the 5-fluorouracil, epirubicin, cyclofosfamide, docetaxel (FEC-D) protocol was 24% and therefore was above the threshold set by the European Organisation for Research and Treatment of Cancer for primary granulocyte colony-stimulating factor (G-CSF) prophylaxis. No relationship between RDI and (disease-free) survival was found with a median follow-up of 38 months. Apart from the stage of disease, obesity is a predictor of poor outcome.

CONCLUSIONS

RDI <85% is predicted by patients' age, febrile neutropenia and hypersensitivity reactions to taxanes. The incidence of febrile neutropenia in FEC-D treatment indicates primary prophylaxis with G-CSF following docetaxel treatment. No relationship was found between RDI and (disease-free) survival, but longer follow-up is needed.