Early-Stage Hodgkin Lymphoma
Similar results were shown in the RAPID trial, in which patients with limited-stage cHL underwent 3 cycles of ABVD followed by PET assessment.67 Patients with a negative PET (n = 426) were then randomized to RT (n = 209) versus no further therapy (n = 211). At a median of 60 months of follow-up, 3-year PFS was 94.6% in the RT group and 90.8% in the chemotherapy alone group. Similar to the H10 trial, it was concluded that chemotherapy alone was statistically inferior to CMT in terms of PFS. However, also similar to the H10 trial, the RAPID trial demonstrated that excellent results can be obtained in early-stage cHL patients with omission of RT, if iPET scan is negative after 3 cycles of ABVD, as there was no survival difference. These findings indicate that, when relapses occur as a result of omission of RT, such patients can be effectively treated later.
In the ongoing GHSG HD16 trial, patients with early-stage favorable cHL will be randomly assigned to a standard approach (ABVD × 2 cycles followed by 20-Gy IFRT) versus an experimental approach in which they receive ABVD for 2 cycles and then undergo PET scan. If the PET remains positive, they will receive 20-Gy IFRT. If the PET is negative, they will receive no further therapy. This trial could ultimately define ABVD for 2 cycles as a treatment option.
It is clear from these studies that omission of RT results in a somewhat higher rate of relapse but can be considered in selected patients. However, taking a less aggressive frontline approach may also be justified by the fact that, for those who do relapse, successful salvage therapies are available. Aggressive salvage therapy with autologous stem cell transplantation historically can cure approximately 50% of relapsed patients. With new and emerging therapies for relapsed disease, such as brentuximab vedotin and the PD-1 inhibitors (eg, nivolumab and pembrolizumab), the ability to cure relapsed patients may improve even more, further calling into question the practice of applying CMT uniformly for early-stage patients undergoing first-line therapy. Unfortunately, there is insufficient data from large randomized studies with long-term follow-up to fully address this issue currently, and there remains some controversy around this issue. NCCN recommends restaging PET/CT after 3 cycles of ABVD if a chemotherapy alone treatment modality is chosen. If the Deauville score is 1 or 2, either observation or 1 additional cycle of ABVD is recommended.46
,Early-Stage Unfavorable cHL
In the United States, historically early-stage unfavorable Hodgkin lymphoma has been treated with CMT, most commonly 4 to 6 cycles of ABVD followed by consolidative RT. With this approach one can expect a 5-year PFS of approximately 80% to 85%.58,64,86 The GHSG HD8 trial showed that RT volume size reduction from extended-field to involved-field after COPP + ABVD chemotherapy for 2 cycles produced similar results and less toxicity in patients with early-stage unfavorable cHL.86 The GHSG trial HD11 established ABVD for 4 cycles plus 30-Gy IFRT as a standard for early unfavorable Hodgkin lymphoma. The freedom from treatment failure at 5 years was 85.0%, and overall survival was 94.5%.68
In the HD14 study by the GHSG, patients with early unfavorable cHL were treated with 2 cycles of escalated BEACOPP followed by 2 cycles of ABVD, versus 4 cycles of ABVD. All patients then received 30 Gy of consolidative IFRT. A 5-year PFS of 95% was seen in the experimental arm, compared with 89% in the standard (ABVD) arm. As expected, this regimen was associated with more acute hematologic toxicity, and there was no difference between the 2 regimens with respect to overall survival or fertility.69 Given the lack of improved survival and increased toxicity, ABVD has remained the standard chemotherapy regimen for early unfavorable cHL in the United States. NCCN recommends a restaging PET scan after 2 cycles of ABVD and to continue with 2 to 4 cycles of ABVD or escalated BEACOPP with or without ISRT based on Deauville scores.
Another viable treatment option is the Stanford V regimen, a condensed, 12-week regimen that includes mechlorethamine, doxorubicin, vinblastine, prednisone, vincristine, etoposide, and bleomycin, followed by IFRT.87 In a randomized phase 3 trial conducted by ECOG (E2496), patients with stage I/II Hodgkin lymphoma with bulky mediastinal disease or advanced-stage disease were randomized to ABVD × 6 to 8 cycles versus Stanford V. RT was given (36 Gy) for those with bulky mediastinal disease or to sites of disease greater than 5 cm in the Stanford V arm. In a subset analysis focusing only on those with stage I/II bulky mediastinal disease, the 5-year failure free survival was 85% versus 79% and the 5-year overall survival was 96% versus 92% for the ABVD versus Stanford V arms, respectively. These differences were not statistically significant.70 While the Stanford V regimen has the advantages of a 12-week treatment duration and a lower cumulative amount of bleomycin and doxorubicin, the Stanford V arm had higher rates of grade 3 lymphopenia and grade 3 to 4 peripheral neuropathies. In addition, Stanford V requires that most patients undergo RT (to original sites of disease measuring 5 cm or more plus contiguous areas). As a result, the investigators concluded that ABVD × 4 cycles plus IFRT remains the standard of care for patients with early unfavorable Hodgkin lymphoma with bulky mediastinal disease.
