Neoadjuvant therapy before surgical treatment

Short-course radiation followed by mFOLFOX-6 plus avelumab for locally-advanced rectal adenocarcinoma

BACKGROUND

Current standard practice for locally advanced rectal cancer (LARC) entails a multidisciplinary approach that includes preoperative chemoradiotherapy, followed by total mesorectal excision, and then adjuvant chemotherapy. The latter has been accompanied by low compliance rates and no survival benefit in phase III randomized trials, so the strategy of administering neoadjuvant, rather than adjuvant, chemotherapy has been adapted by many trials, with improvement in pathologic complete response. Induction chemotherapy with oxaliplatin has been shown to have increased efficacy in rectal cancer, while short-course radiation therapy with consolidation chemotherapy increased short-term overall survival rate and decreased toxicity levels, making it cheaper and more convenient than long-course radiation therapy. This led to recognition of total neoadjuvant therapy as a valid treatment approach in many guidelines despite limited available survival data. With the upregulation (PDL-1) expression in rectal tumors after radiotherapy and the increased use of in malignant melanoma, the novel approach of combining immunotherapy with chemotherapy after radiation may have a role in further increasing pCR and improving overall outcomes in rectal cancer.

METHODS

The study is an open label single arm multi- center phase II trial. Forty-four recruited LARC patients will receive 5Gy x 5fractions of SCRT, followed by 6 cycles of mFOLFOX-6 plus avelumab, before TME is performed. The hypothesis is that the addition of avelumab to mFOLFOX-6, administered following SCRT, will improve pCR and overall outcomes. The primary outcome measure is the proportion of patients who achieve a pCR, defined as no viable tumor cells on the excised specimen. Secondary objectives are to evaluate 3-year progression-free survival, tumor response to treatment (tumor regression grades 0 & 1), density of tumor-infiltrating lymphocytes, correlation of baseline Immunoscore with pCR rates and changes in PD-L1 expression.

DISCUSSION

Recent studies show an increase in PD-L1 expression and density of CD8+ TILs after CRT in rectal cancer patients, implying a potential role for combinatory strategies using PD-L1- and programmed-death- 1 inhibiting drugs. We aim through this study to evaluate pCR following SCRT, followed by mFOLFOX-6 with avelumab, and then TME procedure in patients with LARC.

TRIAL REGISTRATION

Trial Registration Number and Date of Registration: ClinicalTrials.gov NCT03503630, April 20, 2018.

Review of Neoadjuvant Chemotherapy Alone in Locally Advanced Rectal Cancer

BACKGROUND

Currently, the standard management of locally advanced rectal cancer (LARC) is neoadjuvant chemoradiotherapy followed by resection. Despite the significant improvement in local recurrence, survival benefits are not gained due to distant failure and radiotherapy-associated toxicity. Compliance to adjuvant chemotherapy after preoperative chemoradiotherapy is also poor. Neoadjuvant chemotherapy alone followed by surgery may be an alternative. The objective of this review is to determine the efficacy of neoadjuvant chemotherapy alone in operable LARC.

MATERIALS AND METHODS

Electronic databases searched (from database inception-December 2013) were Medline, PubMed, Embase, Scopus, Cochrane library, and the Clinical Trials Register. Specific journals were also hand searched. The selection criteria were studies published in English investigating stage II-III non-metastatic rectal cancer patients treated with neoadjuvant chemotherapy (oral, intravenous or rectal route) followed by curative resection. The primary outcome measure was tumour response. Secondary outcome measures included acute toxicity, operative morbidity, R0 resection, local recurrence, overall survival (OS) and disease-free survival (DFS).

RESULTS

One randomised phase III trial, six single-arm phase II trials and one retrospective case series study were eligible for inclusion. Six studies administered fluoropyrimidine-based multiple agent regimens and two studies administered fluorouracil-based monotherapy. The studies with multiple agents and stronger chemotherapy regimens (intravenous and/or oral) followed by delayed surgery showed better tumour response rates. The overall objective response rate was good and ranged from 62.5 to 93.7 %. Pathological complete response ranged from 3.8 to 33.3 %. The R0 resection and compliance rates were also high ranging from 90 to 100 % and 72 to 100 %, respectively. Grade 3-4 toxicities ranged from 2.3 to 39 %. Four- to 5-year OS and DFS ranged from 67.2 to 91 % and 60.5 to 84 %, respectively.

CONCLUSION

This review demonstrates that neoadjuvant chemotherapy could be affectively administered in LARC and could provide a good alternative to chemoradiotherapy in moderate-risk rectal cancers without compromising short- and long-term outcomes.