The lack of a statistically significant difference in OS may have been due to the fact that patients randomized to receive TACE alone had more frequent post-trial therapies compared with patients assigned to TACE plus sorafenib, said study investigator Masatoshi Kudo, MD, PhD, of the Kindai University faculty of medicine in Osaka, Japan.
“These subsequent anticancer procedures and active systemic therapies have potentially diluted OS benefit in TACE plus sorafenib by extending post-progression survival and confounding survival analysis, implying the OS endpoint is not feasible anymore for TACE combination trials in the era of multitargeted agents and immune checkpoint inhibitors,” Dr. Kudo said at the 2021 Gastrointestinal Cancers Symposium (abstract 270).
Unresectable HCC
The TACTICS trial was launched in October 2010. Investigators enrolled 156 patients with unresectable HCC, Child-Pugh scores of 7 or less, treatable tumors (10 or fewer nodules of 10 cm or less) and adequate organ function.
Patients were randomized to receive TACE alone or with sorafenib. Sorafenib was delivered at a dose of 400 mg daily starting 2-3 weeks before the first TACE procedure to assess tolerability, followed by 800-mg daily doses. Sorafenib was interrupted for 2 days before and 3 days after each TACE session.
The trial had a gate-keeping design, which specified that OS would be formally analyzed only if PFS results were positive.
As reported in GUT in 2020, the trial met its PFS coprimary endpoint, with a median PFS of 25.2 months for the combination, compared with 13.5 months for TACE alone, at a median follow-up of 122.3 weeks. The hazard ratio (HR) for progression with the combination was 0.59 (P = .006).
Updated results
At the symposium, Dr. Kudo presented updated PFS results. At a median follow-up for all randomized patients of 33.4 months, the median PFS with the combination was 22.8 months, compared with 13.5 months for TACE alone (HR, 0.661; P = .02).
However, OS did not differ significantly between the groups, with a median of 36.2 months for the combination and 30.8 months for TACE alone (HR, 0.861; P = .40)
In a subgroup analysis of OS, there were small trends in favor of the combination compared with TACE alone in most categories, but the benefit of the combination was statistically significant only for the 12 patients with HCC of hepatitis B virus etiology (HR, 0.72; 95% CI, 0.006-0.808).
There were also trends favoring TACE plus sorafenib for PFS in a subgroup analysis, but none of the differences were statistically significant, except for patients who had received one or two TACE treatments prior to study entry (HR, 0.474; 95% CI, 0.276-0.812).
Treatment-emergent adverse events were consistent with those seen in the primary analysis, with no new safety signals seen at the last follow-up, Dr. Kudo said.
A majority of patients in both arms had subsequent anticancer therapy – 76.3% of the TACE-alone arm and 58.8% of the combination arm.
Patients in the TACE-alone arm were more likely than were those in the combination arm to have ablation (22.4% vs. 14.9%) or additional sorafenib (50% vs. 10.6%). Patients in the TACE-alone arm were also more likely to receive hepatic artery infusion chemotherapy a single time (27.6% vs. 19.1%) but less likely to receive it continuously (10.3% vs. 19.1%).
Dr. Kudo noted that in six trials in which TACE was combined with another agent, the correlation coefficient between PFS and OS was low, and the slope of weighted linear regression was more gentle than that seen in trials of other therapies for advanced HCC, “suggesting that long post-progression survivals strongly affected the OS in TACE combination trials.”
The TACTICS study was funded by the Japan Liver Oncology Group. Dr. Kudo disclosed relationships with Bayer, codeveloper of sorafenib, and multiple other companies.
The Gastrointestinal Cancers Symposium is sponsored by the American Gastroenterological Association, the American Society for Clinical Oncology, the American Society for Radiation Oncology, and the Society of Surgical Oncology.