Triplet Immunotherapy Shows Durable Response in Relapsed Hodgkin Lymphoma

Redefining Salvage Strategies in Relapsed Classic Hodgkin Lymphoma

Classic Hodgkin lymphoma remains highly curable in the frontline setting, yet approximately 10 percent to 30 percent of patients eventually experience disease relapse or primary refractory status [1]. For these patients, the established standard of care involves salvage chemotherapy followed by high-dose therapy and autologous hematopoietic stem cell transplantation [2]. While the introduction of the antibody-drug conjugate brentuximab vedotin and programmed death-1 inhibitors like nivolumab has significantly improved salvage outcomes, many patients still experience progression after these therapies [3, 4]. Clinicians face a persistent challenge in managing patients who are ineligible for or wish to defer the intensive morbidity associated with transplantation [5]. To address this clinical gap, the Phase 1/2 Intergroup study E4412 (ClinicalTrials.gov identifier NCT01896999) evaluated whether intensifying immunotherapy combinations can provide a viable alternative or a more effective bridge to definitive therapy.

Comparing Doublet and Triplet Immunotherapy Efficacy

The Phase 1/2 Intergroup study E4412 evaluated the efficacy of dual checkpoint blockade using nivolumab and ipilimumab in patients with relapsed or refractory classic Hodgkin lymphoma. This therapeutic strategy concurrently targeted CD30-positive Hodgkin Reed Sternberg cells by incorporating the antibody-drug conjugate brentuximab vedotin into the treatment regimen. The trial randomized 147 patients aged 12 years or older to receive either a doublet of brentuximab vedotin plus nivolumab or a triplet combination of brentuximab vedotin, ipilimumab, and nivolumab. Of the total enrolled population, 132 patients were included in the primary efficacy analysis. The primary endpoint was the complete response rate, defined clinically as the proportion of patients with no detectable evidence of disease after treatment. In the doublet arm, the complete response rate was 64.7% (95% confidence interval [CI], 52.2 to 75.9), while the triplet arm achieved a complete response rate of 70.3% (95% CI, 57.6 to 81.1). Although the triplet therapy showed a higher numerical percentage of complete remissions, the difference between the two arms was not statistically significant (one-sided p=0.29). Consequently, the study did not meet its primary endpoint of demonstrating a superior complete response rate for the triplet therapy. Long-term outcomes were assessed over a median survival follow-up of 38.0 months (interquartile range, 32.6 to 48.1). The researchers measured progression-free survival, which tracks the length of time patients live without their disease worsening. The findings showed that progression-free survival did not significantly differ between the two arms, yielding a hazard ratio of 0.78 (95% CI, 0.39 to 1.57; one-sided p=0.24). While both combinations demonstrated activity in this difficult-to-treat population, the addition of ipilimumab did not provide a statistically significant advantage in the overall cohort for either the depth of initial response or the duration of disease control.

Toxicity Profiles and Dermatologic Adverse Events

Safety considerations are paramount when intensifying immunotherapy regimens, particularly when combining multiple checkpoint inhibitors with an antibody-drug conjugate. In the adult cohort of the study, researchers found that the incidence of treatment-related grade 3 or higher toxicities (severe adverse events that typically require hospitalization or intensive clinical intervention) was comparable between the two treatment groups when dermatologic events were excluded. Specifically, these high-grade toxicities occurred in 38.5% of patients receiving the doublet of brentuximab vedotin plus nivolumab and 39.3% of those in the triplet arm receiving brentuximab vedotin, ipilimumab, and nivolumab. This suggests that the addition of ipilimumab did not substantially increase the burden of non-dermatologic severe systemic side effects, such as colitis or pneumonitis, which are often associated with dual checkpoint blockade. However, a distinct difference emerged regarding dermatologic safety. The study reported that grade 3 rash occurred in 24.6% of patients receiving the triplet combination, a notably higher frequency than the 9.2% observed in the doublet arm. For the practicing clinician, this nearly threefold increase in severe skin toxicity necessitates vigilant monitoring and early intervention with topical or systemic corticosteroids to prevent treatment interruptions. While the overall systemic safety profile remained stable, the increased risk of high-grade dermatologic events represents a primary clinical trade-off when considering the addition of ipilimumab to the salvage regimen.

Long-Term Outcomes and the Role of Transplantation

To better understand how subsequent therapies influenced patient outcomes, the researchers conducted a planned post-hoc comparison (an analysis performed after the primary trial data were collected to explore secondary hypotheses) evaluating outcomes based on stem cell transplantation status. Among the study participants, 58 patients received an autologous stem cell transplantation following their immunotherapy induction. For these individuals, the durability of the response was exceptionally high regardless of the specific induction regimen used. The 36-month progression-free survival from the time of stem cell transplantation was greater than 90% for both the doublet and triplet arms. These data suggest that both regimens serve as highly effective bridges to definitive consolidative therapy. A distinct clinical signal emerged for the 66 patients who were alive and progression-free after their first disease evaluation scan but did not undergo stem cell transplantation. In this subgroup, the triplet combination demonstrated a more durable response over time compared to the doublet. For patients who did not undergo transplantation, the 36-month progression-free survival from the first scan was 73.0% (95% CI, 54.5 to 85.0) for the triplet arm, compared to 45.8% (95% CI, 26.3 to 63.4) for the doublet arm. The hazard ratio for progression-free survival in this non-transplant group was 0.45 (95% CI, 0.19 to 1.08; one-sided p=0.03), indicating a substantially lower risk of disease progression for those receiving the three-drug regimen. While the study did not meet its primary endpoint for the overall population, these findings indicate that the triplet regimen may offer a viable strategy for long-term disease control in select patients who wish to defer or avoid the intensive morbidity associated with stem cell transplantation.

References

1. Shanbhag S, Ambinder RF. Hodgkin lymphoma: A review and update on recent progress. CA A Cancer Journal for Clinicians. 2017. doi:10.3322/caac.21438

2. Armand P, Engert A, Younes A, et al. Nivolumab for Relapsed/Refractory Classic Hodgkin Lymphoma After Failure of Autologous Hematopoietic Cell Transplantation: Extended Follow-Up of the Multicohort Single-Arm Phase II CheckMate 205 Trial.. Journal of clinical oncology : official journal of the American Society of Clinical Oncology. 2018. doi:10.1200/JCO.2017.76.0793

3. Macapagal SC, Lee H, Jabbar JA, et al. Efficacy of Brentuximab Vedotin and Nivolumab in Refractory or Relapsed Hodgkin Lymphoma: A Systematic Review.. Cureus. 2022. doi:10.7759/cureus.23452

4. Herrera AF, Chen L, Nieto Y, et al. Brentuximab vedotin plus nivolumab after autologous haematopoietic stem-cell transplantation for adult patients with high-risk classic Hodgkin lymphoma: a multicentre, phase 2 trial.. The Lancet. Haematology. 2023. doi:10.1016/S2352-3026(22)00318-0

5. Armand P, Engert A, Younes A, et al. Nivolumab for Relapsed/Refractory Classic Hodgkin Lymphoma After Failure of Autologous Hematopoietic Cell Transplantation: Extended Follow-Up of the Multicohort Single-Arm Phase II CheckMate 205 Trial. Journal of Clinical Oncology. 2018. doi:10.1200/jco.2017.76.0793