Trippett, Tanya

ABSTRACT Purpose Despite 5‐year survival rates of over 90% among children and adolescents/young adults (CAYAs) with classic Hodgkin lymphoma (cHL), 15%–20% relapse after frontline therapy. Prior analysis of frontline Children's Oncology Group (COG) clinical trials demonstrated that, despite similar rates of relapse, non‐Hispanic Black (NHB) and Hispanic (vs. non‐Hispanic White [NHW]) patients experienced higher post‐relapse mortality. It is unknown whether post‐relapse disparities persist when second‐line treatment is delivered in a cooperative group trial setting. We examined overall survival (OS) by race and ethnicity in CAYAs enrolled in COG trials for relapsed/refractory (r/r) cHL. Methods A pooled analysis of individual‐level data from CAYAs (≤ 29 years) receiving therapy for r/r cHL on COG clinical trials (2001–2016) was conducted. The Kaplan–Meier method estimated 3‐year OS by racial and ethnic groups. Cox regression models examined associations of race and ethnicity and OS, adjusted for age, insurance, first versus ≥2 relapse, and time from initial diagnosis to relapse trial enrollment. Results Among 175 CAYAs treated on COG trials for r/r cHL (5.7% Asian or Pacific Islander, 14.9% Hispanic, 14.3% NHB, 61.7% NHW, 3.4% other), at median follow‐up of 4.9 years, 3‐year OS was 82.1% (95% confidence interval [CI], 75.3%–87.1%) and did not differ by race and ethnicity ( p = 0.36). In multivariable analyses, shorter time from diagnosis to relapse trial enrollment ( p = 0.01) and ≥2 relapses (vs. first, p = 0.004) conferred worse OS, with no significant effect of race and ethnicity ( p = 0.43). Conclusion Post‐relapse survival did not differ by race and ethnicity among CAYAs enrolled in COG trials for r/r cHL, suggesting access to clinical trials may mitigate OS disparities.

Abstract Background Denintuzumab mafodotin (SGN-CD19A) is an antibody-drug conjugate (ADC) composed of a humanized anti-CD19 monoclonal antibody conjugated to the microtubule-disrupting agent monomethyl auristatin F (MMAF) via a maleimidocaproyl linker. CD19 is a B cell-specific marker that is expressed in nearly all patients (pts) with B-lineage acute leukemia or lymphoma. Methods A phase 1 dose-escalation study is ongoing to evaluate the safety, tolerability, pharmacokinetics, and antitumor activity of denintuzumab mafodotin in pts with relapsed or refractory (R/R) B-ALL, B-cell lymphoma (B-LBL), or Burkitt leukemia/lymphoma (NCT 01786096). Eligible pts are ≥1 year of age and are R/R to ≥1 prior systemic regimen; patients with Philadelphia chromosome-positive (Ph+) disease must have failed a 2nd-generation TKI. A modified continual reassessment method was used for dose allocation and maximum tolerated dose (MTD) estimation. The study evaluated 2 dosing schedules: first weekly (Days 1 and 8 of 21-day cycles) and then once every 3 weeks (q3wk). This report presents data from the adult subset of pts in the study (≥18 years). Results To date, 71 adult pts with R/R B-ALL (n=59), B-LBL (n=6) or Burkitt leukemia/lymphoma (n=6) have been treated; median age is 45 years (range 18−77). Pts received a median of 2 prior therapies (range 1−8); 20 pts (28%) had prior allogeneic stem cell transplant. On the weekly schedule (0.3−3 mg/kg), 40 pts received a median of 2 cycles (range 1−27); 2 pts remain on treatment. On the q3wk schedule (4−6 mg/kg), 31 pts received a median of 3 cycles (range 1−6); 4 pts remain on treatment. An MTD was identified at 5 mg/kg q3wk and was not reached with weekly dosing. Best clinical responses to date for pts with B-ALL are summarized below: Table 1.Response category per Cheson 2003Efficacy-evaluable adult pts with B-ALLweekly dosing, N=32 n (%)q3wk dosing, N=23 n (%)Complete remission (CR)6 (19)3 (13)CR with incomplete platelet recovery (CRp)−3 (13)CR with incomplete blood recovery (CRi)−2 (9)Partial remission (PR)1 (3)−Resistant disease with clinical benefit15 (47)12 (52)Resistant disease without clinical benefit2 (6)-Progression8 (25)3 (13)CRc (CR+CRi+CRp), % (95% CI)19% (95% CI 7, 36)35% (95% CI 16, 57) In the q3wk schedule, the CRc rate was similar at 4, 5, and 6 mg/kg. The median duration of response across schedules is currently 27 weeks (95% CI 7, −). Of 12 pts with CRc and available minimal residual disease (MRD) assessment, 7 were MRD negative. 3 patients with MRD-negative CRs have been in remission for >1 year, 2 of whom have been on continuous treatment for 19 and 22 months. In the subset of pts with Ph+ B-ALL, 4 of 8 pts achieved CR and 1 pt a PR. In 6 pts with Burkitt leukemia/lymphoma, 1 achieved a CR. In 6 pts with B-LBL, objective responses were 1 CR and 2 PR. The adverse event (AE) profiles were similar across both dosing schedules; the most frequently reported AEs were pyrexia (54%), nausea (52%), fatigue (51%), headache (44%), chills (38%), vomiting (37%), blurred vision (35%), and anemia (34%). Ocular symptoms and corneal exam findings consistent with superficial microcystic keratopathy were observed in 40 pts (56%); symptoms were less severe than the associated corneal exam findings. Keratopathy was managed with topical steroids and dose modifications, and improved/resolved within a median of ~3 wks (range 1-17) in pts with sufficient follow-up. ADC exposures increased with dose, and in leukemia patients, target-mediated disposition was observed that diminished with higher doses in the q3wk schedule. Post treatment, flow cytometry data demonstrate that unbound CD19 on peripheral blasts inversely correlates with ADC concentration in circulation, and is present in the majority of evaluable patients at the end of the q3wk cycle. Conclusions Denintuzumab mafodotin is generally well tolerated and demonstrates activity in heavily pretreated adult pts with B-ALL and B-lineage highly aggressive lymphomas, including durable MRD-negative responses. The results of this trial indicate that the q3wk schedule, with a CRc rate of 35% in B-ALL, warrants further clinical investigation. Based on the encouraging responses observed to date in Ph+ B-ALL (CRs in 4 of 8 pts), an expansion cohort of these pts is currently enrolling on the q3wk schedule. Disclosures Fathi: Exelexis: Research Funding; Agios: Membership on an entity's Board of Directors or advisory committees; Merck: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Ariad: Consultancy; Takeda Pharmaceuticals International Co.: Research Funding. Off Label Use: SGN-CD19A is an investigational agent being studied in patients with B-cell malignancies. SGN-CD19A is not approved for use.. Borate:Seattle Genetics: Research Funding; Genoptix: Consultancy; Alexion: Speakers Bureau; Gilead: Speakers Bureau; Novartis: Speakers Bureau; Amgen: Speakers Bureau. DeAngelo:Agios: Consultancy; Incyte: Consultancy; Celgene: Consultancy; Amgen: Consultancy; Pfizer: Consultancy; Bristol Myers Squibb: Consultancy; Ariad: Consultancy; Novartis: Consultancy. O'Brien:Seattle Genetics, Inc.: Research Funding. Trippett:OSI Pharmaceuticals: Research Funding; Seattle Genetics, Inc.: Research Funding. Shah:NCCN: Consultancy; SWOG: Consultancy; Seattle Genetics: Research Funding; Acetylon Pharmaceuticals, INC: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Speakers Bureau; Bayer: Honoraria; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Speakers Bureau; DeBartolo Institute for Personlaized Medicine: Research Funding; Rosetta Genomics: Research Funding; Plexus Communications: Honoraria; Spectrum: Speakers Bureau. Hale:Seattle Genetics, Inc.: Research Funding; Hyundai: Research Funding; V Foundation: Research Funding. Silverman:Seattle Genetics, Inc.: Research Funding. Pauly:Seattle Genetics, Inc.: Research Funding. Kim:Bayer: Consultancy; Seattle Genetics, Inc.: Consultancy, Research Funding; Eli Lilly: Consultancy. Kostic:Seattle Genetics, Inc.: Employment, Equity Ownership. Huang:Seattle Genetics, Inc.: Employment, Equity Ownership. Pan:Seattle Genetics, Inc.: Employment, Equity Ownership. Chen:Genentech: Consultancy, Speakers Bureau; Seattle Genetics, Inc.: Consultancy, Other: Travel expenses, Research Funding, Speakers Bureau; Millennium: Consultancy, Research Funding, Speakers Bureau.

Abstract Background CD19, a B cell-specific marker, is expressed in the majority of patients with B-lineage leukemia and non-Hodgkin lymphoma. SGN-CD19A is a novel antibody-drug conjugate (ADC) composed of a humanized anti-CD19 monoclonal antibody conjugated to the microtubule-disrupting agent monomethyl auristatin F (MMAF) via a maleimidocaproyl linker. Methods This first-in-human, phase 1, open-label, dose-escalation study is investigating the safety, tolerability, pharmacokinetics, and antitumor activity of SGN-CD19A in adult and pediatric patients with relapsed or refractory B-cell leukemia or highly aggressive lymphoma (NCT 01786096). Eligible patients must have B-cell acute lymphoblastic leukemia (B-ALL) or lymphoma (B-LBL), Burkitt leukemia or lymphoma, and be relapsed or refractory to at least 1 prior systemic regimen. A modified continual reassessment method is used for dose allocation and maximum tolerated dose (MTD) estimation for both pediatric and adult patients. The study is evaluating 2 schedules of IV SGN-CD19A administration: weekly (Days 1 and 8 of 21-day cycles; 0.3-4.5 mg/kg) or every 3weeks (q3week; 0.5-6 mg/kg). Results To date, 49 patients with relapsed or refractory leukemia (n=40) or lymphoma (n=9) have been treated. Median age of adult (n=38) and pediatric patients (n=11) was 37 and 11 years (range, 18-74 and 1-16), respectively. Patients received a median of 2 prior therapies (range 1-9); 14 patients (29%) previously received an allogeneic stem cell transplant. On the weekly schedule, 39 patients (28 adult, 11 pediatric) have been treated, and the median number of cycles is 2.5 (adults; range, 1-12) or 1 (pediatric; range, 1-4). On the q3week schedule, 10 adult patients have been treated, and the median number of cycles is 2.5 (range, 1-4) to date. Six patients remain on study treatment (3 on each schedule), and enrollment is ongoing. The toxicity profiles were similar across both dosing schedules (0.3-2.3 mg/kg weekly and 4-5 mg/kg q3week) and across adult and pediatric patients. The most frequently reported drug-related AEs included pyrexia, nausea, chills, vomiting, blurred vision, and dry eye. Frequent infusion-related reactions were observed early in the study, and recommendation for premedication was instituted. Ocular events were also observed and treated with ophthalmic steroids; steroid eye drop prophylaxis was instituted with each dose. Corneal findings consistent with superficial microcystic keratopathy were observed in 13 adult patients (34%) and in 1 pediatric patient (9%). Grade 3/4 corneal AEs have been observed in 4 adult patients; the majority of these events have resolved or improved to Grade 1 or 2. Steroid eye drop prophylaxis has reduced the incidence of Grade 3/4 events at this interim analysis. Three DLTs were observed: acidosis in a pediatric patient at 1 mg/kg weekly, cytokine release syndrome in an adult patient at 2 mg/kg weekly, and asymptomatic Grade 4 AST elevation in an adult patient at 5 mg/kg q3week. MTD has not yet been determined. SGN-CD19A ADC pharmacokinetic profiles indicate target-mediated drug disposition in patients with leukemia. Plasma ADC exposures generally increased with doses and were lower than those in patients with lymphoma. To date, no objective responses were observed in 9 efficacy-evaluable pediatric patients or in 3 adult patients with Burkitt lymphoma/leukemia. However, in efficacy-evaluable adult patients with B-ALL/B-LBL, objective responses were observed in 6 of 25 patients treated on the weekly schedule (3 CR, 2 CRp, 1 PR), and in 4 of 8 patients treated on the q3week schedule (2 CR, 2 CRp). Of 8 B-ALL patients with CR/CRp, 6 were MRD negative. Conclusions MTDs have not yet been identified, and dose escalation continues on weekly and q3week schedules. SGN-CD19A has been generally well tolerated. At this interim analysis, objective responses were observed in 30% (10 of 33) of heavily pretreated adult B-ALL/B-LBL patients dosed weekly or q3week. Evidence of activity in relapsed/refractory patients and lack of overlapping toxicities suggest opportunities for combination with conventional anti-leukemic therapies in lymphoblastic malignancies. Disclosures Fathi: Ariad: Consultancy; Exelixis: Research Funding; Takeda pharmaceuticals International Co.: Research Funding; Seattle Genetics, Inc.: Consultancy, Research Funding. Off Label Use: SGN-CD19A is an investigational agent being studied in patients with B-cell malignancies. SGN-CD19A is not approved for use. . Chen:Seattle Genetics, Inc.: Consultancy, Research Funding, Speakers Bureau, Travel expenses Other. Trippett:OSI Pharmaceuticals: Research Funding; Seattle Genetics, Inc.: Research Funding. O'Brien:Seattle Genetics, Inc.: Research Funding. DeAngelo:Seattle Genetics, Inc.: Research Funding. Shah:Pharmacyclics: Consultancy; SWOG: Consultancy; Celgene: Consultancy, Speakers Bureau; NCCN: Consultancy; Seattle Genetics, Inc.: Research Funding; Janssen: Consultancy. Cooper:Seattle Genetics, Inc.: Research Funding. Foran:Seattle Genetics, Inc.: Research Funding. Hale:Seattle Genetics, Inc.: Research Funding. Pressey:Seattle Genetics, Inc.: Research Funding. Silverman:Seattle Genetics, Inc.: Research Funding. Tibes:Seattle Genetics, Inc.: Research Funding. Kim:Bayer: Consultancy; Eli Lily: Consultancy; Seattle Genetics, Inc.: Consultancy, Research Funding. Albertson:Seattle Genetics, Inc.: Employment, Equity Ownership. Sandalic:Seattle Genetics, Inc.: Employment, Equity Ownership. Zhao:Seattle Genetics, Inc.: Employment, Equity Ownership. Borate:Genoptix: Consultancy; Seattle Genetics, Inc.: Research Funding.