Phase II study of preoperative radiotherapy and concomitant weekly intravenous oxaliplatin combined with oral capecitabine for stages II–III rectal cancer

Pilot Study of Intense Neoadjuvant Chemoradiotherapy for Locally Advanced Rectal Cancer: Retrospective Review of a Phase II Study

Aims and Background

Locally advanced rectal adenocarcinoma is typically treated with neoadjuvant chemoradiotherapy and surgery. We assessed the effect of an additional cycle of capecitabine/oxaliplatin chemotherapy before surgery in 57 patients with T3/4, N+/- or T1/2, N+ rectal cancer.

Materials and Study Design

Radiotherapy (total dose, 50.4 Gy) was combined with three cycles of chemotherapy (two cycles concomitant with radiotherapy), and each cycle consisted of oxaliplatin (130 mg/m2 on day 1) and capecitabine (825 mg/m2, twice per day from day 1 to day 14) for 21 days. In addition to assessing the safety of this treatment, the primary endpoint was pathological complete response (pCR). The secondary endpoint was the change in primary tumor and node stage from pre-treatment to post-surgery.

Results

Eleven patients (19%) experienced complete tumor regression and 23 patients (40%) experienced tumor regression grade 3. Tumor down-staging occurred in 31 patients (54.4%) and down-staging of nodes occurred in 25 patients (43.9%). There was a significant difference in tumor stage between pre-treatment and post-surgery (P <0.001). Patients with less advanced N stages had significantly better recurrence-free survival but similar metastasis-free survival and overall survival. Tumor regression grade was not associated with overall survival, recurrence-free survival or metastasis-free survival. The most common adverse events were pulmonary infection (n = 6, 10.5%) and intestinal obstruction (n = 6, 10.5%).

Conclusions

An additional cycle of chemotherapy given after chemoradiotherapy and before surgery provided good efficacy and had a satisfactory safety profile in patients with locally advanced rectal cancer.

Addition of oxaliplatin to capecitabine-based preoperative chemoradiotherapy for locally advanced rectal cancer: Long-term outcome of a phase II study

Our previous study reported the favorable short-term outcome and good tolerance of integrating oxaliplatin into capecitabine-based (XELOX regimen) preoperative chemoradiotherapy (CRT) for locally advanced rectal cancer (LARC). The present study reported the long-term oncological outcome of this phase II study. A total of 47 patients with rectal adenocarcinoma (stage II or III) were enrolled and received radiotherapy (46 Gy in 23 fractions) in combination with capecitabine (1,000 mg/m², twice daily, on days 1–14 and 22–35) and oxaliplatin (130 mg/m² on days 1 and 22). Overall survival (OS) rate, disease-free survival (DFS) rate and cumulative incidence of recurrences and long-term complications were calculated or observed. As a result, 41 patients underwent surgery after preoperative CRT, and the cumulative OS rates at 1, 3 and 5 years for these patients were 100.0, 84.5 and 81.8%, respectively. For the 38 patients who received R0 resection, the cumulative OS rates at 1, 3 and 5 years were 100.0, 89.0 and 86.2%, respectively, while the cumulative DFS rates at 1, 3 and 5 years were 94.6, 75.3 and 69.7%, respectively. After follow-up at 84 months, the cumulative incidence rates of local and distant recurrences at 5 years were 6.6 and 28.2%, respectively. Oxaliplatin-associated long-term complications were seldom observed. Overall, the addition of oxaliplatin to capecitabine-based preoperative radiotherapy achieved favorable OS and DFS without increased long-term complications in patients with LARC. Therefore, this preoperative CRT strategy is a feasible option for such patients.

Phase 2 Neoadjuvant Treatment Intensification Trials in Rectal Cancer: A Systematic Review

PURPOSE

Multiple phase 2 trials of neoadjuvant treatment intensification in locally advanced rectal cancer have reported promising efficacy signals, but these have not translated into improved cancer outcomes in phase 3 trials. Improvements in phase 2 trial design are needed to reduce these false-positive signals. This systematic review evaluated the design of phase 2 trials of neoadjuvant long-course radiation or chemoradiation therapy treatment intensification in locally advanced rectal cancer.

METHODS AND MATERIALS

The PubMed, EMBASE, MEDLINE, and Cochrane Library databases were searched for published phase 2 trials of neoadjuvant treatment intensification from 2004 to 2016. Trial clinical design and outcomes were assessed, with statistical design and compliance rated using a previously published system. Multivariable meta-regression analysis of pathologic complete response (pCR) was conducted.

RESULTS

We identified 92 eligible trials. Patients with American Joint Committee on Cancer stage II and III equivalent disease were eligible in 87 trials (94.6%). In 43 trials (46.7%), local staging on magnetic resonance imaging was mandated. Only 12 trials (13.0%) were randomized, with 8 having a standard-treatment control arm. Just 51 trials (55.4%) described their statistical design, with 21 trials (22.8%) failing to report their sample size derivation. Most trials (n=84, 91.3%) defined a primary endpoint, but 15 different primary endpoints were used. All trials reported pCR rates. Only 38 trials (41.3%) adequately reported trial statistical design and compliance. Meta-analysis revealed a pooled pCR rate of 17.5% (95% confidence interval, 15.7%-19.4%) across treatment arms of neoadjuvant long-course radiation or chemoradiation therapy treatment intensification and substantial heterogeneity among the reported effect sizes (I² = 55.3%, P<.001). Multivariable meta-regression analysis suggested increased pCR rates with higher radiation therapy doses (adjusted P=.025).

CONCLUSIONS

Improvement in the design of future phase 2 rectal cancer trials is urgently required. A significant increase in randomized trials is essential to overcome selection bias and determine novel schedules suitable for phase 3 testing. This systematic review provides key recommendations to guide future treatment intensification trial design in rectal cancer.