Older Patients (pts) with Previously Untreated Classical Hodgkin Lymphoma (cHL): A Detailed Analysis from the Phase 3 ECHELON-1 Study

Background

Survival rates for older pts with advanced HL (aged ≥60 yrs) were historically poor with doxorubicin, bleomycin, vinblastine and dacarbazine (ABVD). Reasons may include decreased tolerance of therapy, increased toxicity (particularly with bleomycin), comorbidities, and disease biology. The pivotal phase 3 ECHELON-1 study demonstrated superior 2-yr modified progression-free survival (mPFS) with frontline brentuximab vedotin + doxorubicin, vinblastine and dacarbazine (A+AVD) vs ABVD in pts with stage III/IV cHL (Connors JM et al, NEJM 2018). The study allowed entry of older pts, with no upper age limit. Alternative dosing schedules of the A+AVD regimen have been studied (e.g., sequential brentuximab vedotin before and after AVD; NCT01476410, Evens AM et al, J Clin Oncol 2018). We report efficacy and safety results from ECHELON-1 for older pts with cHL and compare these with those for pts aged <60 yrs.

Methods

mPFS per independent review facility (IRF) for pts ≥60 years was a prespecified subgroup analysis of ECHELON-1. Additional exploratory safety and efficacy analyses were also assessed and compared with younger pts (<60 yrs). The study was not powered for age-based subgroup analyses; p-values are descriptive without multiplicity adjustment.

Results

14% (186/1334) of pts in the intent-to-treat (ITT) population were aged ≥60 yrs (A+AVD, n=84; ABVD, n=102) and included in the sub analyses. Median age (range) of older pts was: A+AVD, 68.0 yrs (60-82); ABVD, 66.0 yrs (60-83). Baseline pt and disease characteristics in older pts were similar in both arms. ECOG PS scores were 0 (36% vs 36%), 1 (52% vs 54%), and 2 (12% vs 10%) in A+AVD and ABVD arms, respectively. Pts received a median of 6 cycles with mean relative dose intensities for each drug (%) in older pts of: A+AVD, 92.3, 96.6, 93.3, and 97.9; ABVD, 97.3, 88.7, 93.3, and 95.9. With median follow-up of ~25 months, 2-yr mPFS per IRF was similar in both arms for older ITT pts (A+AVD 70.3% [95% CI: 58.4, 79.4] vs ABVD 71.4% [95% CI: 60.5, 79.8]; HR=1.00 [95% CI: 0.58, 1.72]; p=0.993). An exploratory analysis of standard PFS per investigator (INV) showed HR=0.85 ([95% CI: 0.49, 1.48]; p=0.576) (Table 1). For older pts with stage IV cHL (A+AVD n=51; ABVD n=67), there was an increase in 2-yr PFS per INV with A+AVD vs ABVD (74.0% [95% CI: 59.5, 84.0] vs 59.9% [95% CI: 45.6, 71.5]; HR, 0.66 [95% CI: 0.34, 1.26]; p=0.20); mPFS per IRF improvement with A+AVD in older stage IV pts was lower (HR=0.80; [95% CI: 0.42, 1.53]). In younger stage III/IV pts (<60 yrs) 2-yr mPFS per IRF and PFS per INV were also higher compared with older pts in both arms (Table 1). 66 of 83 older A+AVD pts required ≥1 dose modification of brentuximab vedotin, reasons were: dose reduction (n=27), dose held (n=4), dose delayed (n=51), brentuximab vedotin discontinued (n=17). In older pts, grade (G) 3/4 AEs occurred in 88% of A+AVD pts vs 80% ABVD pts; for younger pts, rates were 82% (A+AVD) vs 63% (ABVD) (Table 2). In older pts there were 3 (4%) on-study deaths in the A+AVD arm (1 each: hemophagocytosis, neutropenic sepsis, and myocardial infarction) and 5 (5%) with ABVD (all pulmonary-related). In pts <60 yrs, there were 6 on-study deaths (1%) with A+AVD vs 8 (1%) with ABVD. G3 neutropenia in older pts was (70%) A+AVD pts vs (59%) ABVD pts, and febrile neutropenia (FN) in 31 (37%) vs 17 (17%) pts. In older pts who had G-CSF primary prophylaxis (PP) neutropenia was seen in 4/10 (40%) A+AVD pts vs 1/9 (11%) ABVD pts (on-study FN in 3 [30%] vs 2 [22%] pts). In older pts, treatment-emergent peripheral neuropathy (PN) was reported in 54 (65%) of A+AVD pts vs 42 (43%) of ABVD pts (G≥3 in 15 [18%] vs 3 [3%] pts), respectively. In pts <60 yrs PN was reported in 388 (67%) A+AVD pts vs 244 (43%) ABVD pts (G≥3 in 55 [9%] vs 8 [1%] pts), respectively. In older pts at last follow-up, 65% (35/54) of A+AVD pts and 60% (25/42) of ABVD pts had complete resolution (A+AVD, 39%; ABVD, 38%) or improvement (A+AVD, 26%; ABVD, 21%) of PN events. 2% older A+AVD pts had pulmonary AEs (both G1/2 pulmonary infiltration) vs 13% older ABVD pts.

Conclusions

For older ECHELON-1 pts, mPFS and PFS were similar in both arms. In the larger subgroup of younger pts, mPFS and PFS were improved vs older pts. As expected, incidence of treatment-emergent AEs was higher in older pts, with regimen-specific AEs seen, including fatal pulmonary events in ABVD pts. The high incidence of FN in older A+AVD pts points to the need for G-CSF PP.

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