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24-01-2018 | Colorectal cancer | News

No advantage to continuing bevacizumab after induction chemotherapy in mCRC

medwireNews: Maintenance treatment with bevacizumab monotherapy following induction chemotherapy has no benefit for metastatic colorectal cancer (mCRC) patients, PRODIGE 9 trial findings show.

Among 494 patients who received 12 cycles of FOLFIRI plus bevacizumab 5 mg/kg every 2 weeks of induction chemotherapy, median tumor control duration (TCD) was 15 months for the 247 who went on to receive bevacizumab maintenance therapy during chemotherapy-free intervals and the 247 who were observed.

Thomas Aparicio (Saint Louis Hospital, Paris, France) and colleagues thought that bevacizumab might extend TCD by 10 to 14 months but instead found “a[n] unexpected prolonged TCD in both arms.”

There was also no delay in reprogression with maintenance treatment, the researchers note in the Journal of Clinical Oncology, and, therefore, “[f]rom a health care economic point of view, avoiding unnecessary bevacizumab treatment can result in substantial cost savings.”

Maintenance treatment offered no advantage over observation in terms of progression-free survival and overall survival, which were 9.2 months versus 8.9 months, and 21.7 versus 22.0 months, respectively.

And while TCD and overall survival were further prolonged in a group of 261 patients who underwent at least one reinduction chemotherapy regimen after the first progression, there was again no significant difference between the treatment groups. The median TCD was 17.8 with maintenance therapy and 23.3 months without, while overall survival was a corresponding 27.6 and 28.5 months.

“It is noteworthy that fewer successive reinductions of chemotherapy took place in the maintenance arm,” the researchers point out. “Although there is not a clear explanation for this finding, it may have affected the primary end point.”

They add that more toxicities, particularly cardiovascular toxicities, occurred in patients receiving maintenance treatment and this may partly explain the lack of reinduction of chemotherapy.

The team was unable to find subgroups of patients who would be more likely to benefit from bevacizumab maintenance treatment, although a poorer survival prognosis was seen for patients with an unresected primary tumor, a WHO performance status above 2, a BRAF mutation, or more than one metastatic site. A finding the researchers say “encourages the conduct of a specific trial in this subgroup of patients.”

They conclude that “bevacizumab monotherapy has no effect when used as maintenance treatment after induction chemotherapy,” and call for “[a]dditional research… to better define subgroups of patients who should receive maintenance chemotherapy after induction treatment or could undergo a true chemotherapy-free interval.”

By Lucy Piper

medwireNews is an independent medical news service provided by Springer Healthcare. © 2018 Springer Healthcare part of the Springer Nature group