This phase 2, open-label, multicenter study was designed to evaluate the efficacy and safety of BV in patients with relapsed or refractory high-CD30–expressing NHL other than ALCL. All subtypes of NHL including mature B-, T-, or NK-cell lymphomas except ALCL were eligible for enrollment. Because all patients were initially diagnosed with NHL before 2017, NHL subtype was classified based on the World Health Organization’s 2008 criteria. The primary study objective was to determine the overall rate of disease control, defined as complete response (CR), partial response (PR), and stable disease (SD). Secondary objectives included determining toxicity profiles, progression-free survival (PFS), and overall survival (OS). Patients received 1.8 mg/kg BV intravenously every 3 weeks. Those who achieved SD or better continued to receive treatments up to a maximum of 16 cycles. However, in the event of progressive disease (PD) or unacceptable toxicity, BV administration should be discontinued; dose reduction to 1.2 mg/kg and treatment delay up to 3 weeks was allowed, depending on the type and severity of toxicity, including peripheral neuropathy. Blood transfusion or granulocyte colony-stimulating factors were allowed for patients with anemia, thrombocytopenia, and neutropenia. Response evaluation was completed by the investigator according to the 2007 Revised International Working Group Response Criteria for Malignant Lymphoma [21]. Baseline assessment was performed by using computed tomography (CT) and fluorine-18 deoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) of the neck, chest, abdomen, and pelvis prior to the first treatment cycle. Restaging assessment was performed by CT and PET/CT after the second cycle. Additional response evaluations for preexisting lesions were evaluated after the fourth, eighth, twelfth, and sixteenth cycles by CT scan. For apparently new lesions unobserved on pretreatment or other posttreatment scans, PET/CT was performed to confirm disease progression. Toxicity was assessed from the first dose to 4 weeks following the last BV dose and adverse events were graded using ver. 4.0.3 of the National Cancer Institute Common Terminology Criteria for Adverse Events. Assessment of disease and survival status took place every 3 months per institutional standards of care and thereafter until study closure or withdrawal of consent for patients who received at least one dose of BV.

There were five eligibility criteria. (1) Any subtype of histologically confirmed high-CD30–expressing NHL, except ALCL. High CD30 expression was defined as membranous CD30 expression in ≥ 30% of tumor cells detectable by visual assessment of routine immunohistochemistry staining using the anti-CD30 antibody on biopsy at the time of diagnosis or relapse. (2) A bidimensionally measurable lesion ≥ 1.5 cm in the greatest transverse diameter. (3) Age 20-75 years and an Eastern Cooperative Oncology Group performance status of ≤ 2. (4) Adequate bone marrow and organ function. (5) No history of another active cancer within the previous 5 years except basal cell carcinoma. Note that patients who had relapsed after autologous stem cell transplantation (SCT) were considered eligible. Exclusion criteria were: undergoing allogeneic SCT; active infection, human immunodeficiency virus infection, or hepatitis B or C; and lymphomatous involvement of the central nervous system. The 30% cutoff was established by consensus during an investigation initiation meeting of the pathologists from each of the study sites after they reviewed various cutoff values for ‘positive’ and ‘strong positive’ of CD30 expression across various subtypes of NHL [4-12].

Sample size was calculated to reject the null with a 20% overall disease control rate but increased to favor of a target rate of 40% with significance 0.05 and power 80% using Simon’s Minimax two-stage design [22]. Thus, if the rate was less than 4/18 during the first stage, the study would be stopped. If not, patient recruitment would be continued until n=33. Patients’ clinical characteristics, demographics, and treatment outcomes were analyzed based on the NHL subtype, and chi-squared tests were used to evaluate their relationships with outcomes. OS was calculated from the first date of BV infusion to final follow-up or death from any cause. PFS was calculated from the first date of BV infusion to the date of disease progression or death from any cause. Median potential follow-up time with 95% confidence interval (CI) was determined using the Kaplan-Meier method [23]. Survival was estimated based on Kaplan-Meier curves and compared using the log-rank test. Two-sided p < 0.05 was considered statistically significant.

Quantified CD30 expression from tumor cells was compared with determined response to BV. Immunohistochemistry was performed on 4-μm paraffin sections following routine protocols using a fully automated platform at each institute; CD30 was detected using a ready-to-use antibody (clone BerH2, Dako, Carpinteria, CA). EBV in situ hybridization and MUM1 expression were analyzed in patients who had tissue sample available for analysis. The presence of EBV-positive tumor cells was considered EBV positivity regardless of its percentage whereas MUM1-positivity was defined as more than 30% of tumor cells were positively stained. Immunohistochemistry for MUM1 (MUM1p, Dako) was also performed for exploratory biomarker development. Differences in biomarkers between responder subgroups were compared via post-hoc analysis using the chi-square test.

The study was conducted by the Consortium for Improving Survival of Lymphoma (CISL) in compliance with the Declaration of Helsinki and the International Conference on Harmonization Good Clinical Practice. The Korean Food and Drug Administration approved this study (No. 30229), and each study site obtained approval from their local institutional review board. All patients gave written informed consent prior to study participation. The study was registered at ClinicalTrials.gov (NCT02280785).

In total, 33 patients were enrolled between March 2015 and January 2017 from five hospitals belonged to the CISL. Their median age at enrollment was 56 years (range, 27 to 73 years); other characteristics at enrollment are summarized in Table 1. Stage III/IV patients accounted for 79% (26/33) of the sample and 70% had elevated levels of serum lactate dehydrogenase. All patients were treated with at least one line of salvage chemotherapy. The median number of prior therapies was three (range, 2 to 10) and seven patients relapsed after autologous SCT. At enrollment, 10 patients had relapsed after their last chemotherapy and 22 were refractory after previous treatment (Table 1). The most common subtypes were DLBCL (n=12) including one patient with relapsed DLBCL who was initially diagnosed with angioimmunoblastic T-cell lymphoma (AITL) and peripheral T-cell lymphoma not otherwise specified (PTCL-NOS; n=8); other subtypes included ENKTL (n=7), PMBCL (n=3), transformed MF (n=2), and AITL (n=1). The median percentage of CD30-positive tumor cells was 50% (range, 30% to 100%), and 60% of patients (n=20) had ≥ 50% of CD30 expression (Table 1).

Twelve patients achieved CR (n=6) or PR (n=6) and four patients’ best response was SD; thus, the overall disease control rate was 48.5% (16/33). However, the remaining 17 patients were dropped due to early progressive disease after the first or second BV cycle. Among 12 patients with CR or PR, six (4CR, 2PR) completed 16 cycles, maintaining their response, whereas the others showed disease progression during treatment (Fig. 1A). A 70-year-old female patient with PTCL-NOS discontinued the treatment because she developed a stroke prior to her second cycle. Although her response evaluation showed SD, she could not receive further treatment. The waterfall plot for responders showed a significant change from baseline tumor size compared to nonresponders (Fig. 1B). The median number of treatment cycles was two (range, 1 to 16), however, the median cycle number for the 16 patients with CR, PR, or SD was 7.5. The overall rates of disease control in patients with DLBCL (2CR, 2PR, 2SD; 6/12, 50%), PTCL-NOS (2CR, 1PR, 2SD; 5/8, 62.5%), and transformed MF (2PR; 2/2, 100%) were higher compared with those with ENKTL (1CR, 1PR; 2/7, 29%), PMBCL (1CR; 1/3, 33%), and AITL (0/1, 0%) albeit with small subtype samples (Fig. 2A). When response to BV was compared based on disease status prior to BV, there was no significant difference between patients with relapsed (3CR, 2PR, 1SD; 6/11, 54.5%) and refractory disease (3CR, 4PR, 3SD; 10/22, 45.5%, p=0.721).

Although we only enrolled patients with high-CD30–expressing NHL, this sample had a wide range of CD30 expression values (30%-100%). Based on their percentage of CD30-positive tumor cells, patients were grouped as 30%-49% (n=13), 50%-79% (n=9), or 80%-100% (n=11). The number of patients with CR and PR did not differ significantly based on these groupings (46%, 6/13 vs. 11%, 1/9 vs. 46%, 5/11; p=0.182) (Fig. 2B). Nor did overall disease control rate differ (46%, 6/13 vs. 22%, 2/9 vs. 64%, 7/11; p=0.180). Although transformed MF (n=2; patients 25 and 26) showed 90% and 100% CD30 expression, respectively, their best response was PR and was not durable (Fig. 1). No other subtypes showed a significant association between CD30 expression and response to BV.

With a median follow-up of 29.2 months (95% CI, 28.7 to 29.7 months), eight patients were alive and their best responses were 4CR, 3PR, and 1PD. Among these, two patients (patients Nos. 13 and 16) maintained CR without any evidence of disease relapse. Five responders (2CR, 3PR) showed relapse or disease progression during treatment or after completion of 16 cycles; however, they were alive because of rescue by subsequent chemotherapies, including one case of transfor-med MF (patient 26) who received allogeneic SCT (Fig. 1). The one patient with ENKTL showing early PD (patient 27) was alive after responding to salvage treatments. Thus, the median duration of objective response (CR and PR) was 6.0 months (range, 3.9 to 35.0 months). However, the remaining patients died and the majority showed early PD after the first or second cycle of BV. As a result, the median PFS and OS for all patients were 1.9 months (95% CI, 0.6 to 3.2 months) and 6.1 months (95% CI, 4.5 to 7.7 months), respectively (Fig. 2C). OS among patients responding to BV was significantly better than that of patients with SD or PD (Fig. 2D). Although not statistically significant, the survival outcome among patients who were refractory to previous treatments prior to BV was inferior to that of patients with relapsed disease after a previous treatment (Fig. 2E). However, OS did not differ based on CD30 expression (30%-49% vs. 50%-79% vs. ≥ 80%) (Fig. 2F). Nor did OS differ between subtypes, although these samples were small (data not shown).

Treatment-emergent adverse events were reported in 31 patients (93.9%), all of which are summarized in Table 2. Grade 3 or worse adverse events occurred in 23 patients (69.7%). Serious adverse events were reported in 18 patients (54.5%); the most common serious adverse event was fever (n=4). Other serious adverse events included herpes zoster (n=2), urinary tract infection (n=1), sinusitis (n=1), dyspnea (n=1), diarrhea (n=1), anorexia (n=1), and perianal abscess (n=1). Increase in creatinine was associated with tumor lysis syndrome (n=1). Suicide attempt occurred in one patient (patient 11) after the first cycle; however, the patient was able to continue receiving BV until PD. Patient No. 19's serious adverse event, stroke, led to study discontinuation (Fig. 1). The remaining three patients were admitted to the hospital due to disease progression during the study. The most common adverse events, occurring in ≥ 20% of patients, included fever (39%), neutropenia (30%), fatigue (24%), and peripheral sensory neuropathy (27%) (Table 2). Gastrointestinal symptoms, including diarrhea, nausea, and vomiting were also commonly observed, and upper respiratory infection, rhinosinusitis, and skin rash were common adverse events in ≥ 10% of patients (Table 2).

EBV positivity was not significantly associated with the percentage of CD30 expression in the analysis of 29 patients with available EBV status (Fig. 3A). MUM1 expression was assessed by immunohistochemistry in 24 patients whose tumor tissue was available for study. Nine patients showed negativity for MUM1 (DLBCL 1, PMBCL 1, PTCL 3, and ENKTL 4) whereas the remaining 15 patients were positive for MUM1 (DLBCL 9, PMBCL 2, PTCL 2, and ENKTL 2). MUM1 negativity was more common in 30%-49% of CD30 expression whereas MUM1-negative cases were not observed in 80%-100% of CD 30 expression (Fig. 3B). Among nine patients negative for MUM1, five responded to BV (4CR, 1PR, 55.6%), whereas only two responded to BV (1CR, 1PR, 13.3%) out of the 15 MUM1-positive patients (Fig. 3C). Although their association with response was not statistically significant (p=0.061), the PFS and OS of MUM1-negative patients were significantly higher compared with MUM1-positive patients (Fig. 3D and E). When response was compared based on EBV positivity of tumor cells, using 29 patients with available EBV status, the response to BV among patients with EBV-positive tumor (35.3%, 6/17) did not differ significantly from those with EBV-negative tumors (25.0%, 3/12; p=0.694). Accordingly, OS did not differ between EBV-positive and -negative patients (p=0.588) (Fig. 3F).

Patients’ best responses could be clearly identified by PET/CT because patients achieving CR showed complete disappearance of FDG uptake (Fig. 4A and B). However, some patients showed heterogeneous responses of involved sites. For example, one patient with PTCL (patient No. 18) showed PR after the second cycle (Fig. 4C). His remaining target lesions disappeared after the 12th cycle, although new lesions appeared. He continued to receive BV, based on the investigator’s decision; however, PD was discovered 2 months after the completion of planned treatment. Two patients (patients Nos. 3 and 4) with DLBCL showed PD after the second cycle of BV, although their responses differed according to the sites involved, with several lesions disappearing and others progressing (Fig. 4D and E).