ASCO Annual Meeting

ASCO Annual Meeting

June 03, 2015
2 min read

Lower dose of polatuzumab vedotin safe, effective for follicular lymphoma

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CHICAGO — A lower dose of polatuzumab vedotin combined with rituximab yielded comparable overall response rates as a higher dose yet improved toxicity among patients with relapsed or refractory follicular lymphoma, according to study results presented at the ASCO Annual Meeting.

“Polatuzumab vedotin is an anti-CD79b antibody-drug conjugate,” Ranjana H. Advani, MD, professor of lymphoma at Stanford University, said during a presentation. “CD79b is a component of the B-cell receptor and is expressed in nearly all B-cell malignancies. Clinical activity has been observed in relapsed and refractory non-Hodgkin’s lymphoma at doses greater than or equal to 1.8 mg/kg in a phase 1 trial. Subsequently, two dose levels — 1.8 mg/kg and 2.4 mg/kg — were assessed in a phase 2 trial in relapsed and refractory follicular lymphoma, but the optimal duration of therapy is unknown.”

Previous studies also have demonstrated cumulative toxicity with the 2.4 mg/kg dose. Thus, researchers sought to compare the safety and efficacy of lower and higher doses of polatuzumab vedotin (anti-CD79b ADC, Genentech) plus rituximab (Rituxan, Genentech/Biogen Idec).

Advani and colleagues assigned 35 patients with relapsed or refractory to 375 mg/m2 rituximab with 1.8 mg/kg (n = 10) or 2.4 mg/kg (n = 25) polatuzumab vedotin every 3 weeks until the occurrence of an unacceptable toxicity.

Patients in the higher-dose cohort were older (median age, 68 years vs. 62 years) and had less tumor volume (1,824 mm2 vs. 2,655 mm2). Forty percent of patients in the higher-dose cohort and 50% in the lower-dose cohort were refractory to their last treatment.

Researchers compared data at the completion of polatuzumab vedotin treatment with data after eight treatment cycles.

Median follow-up was 14 months for the 2.4-mg/kg cohort and 8 months for the 1.8-mg/kg cohort.

Researchers observed a nearly identical overall response rate in the 2.4-mg/kg cohort (76%) and the 1.8-mg/kg cohort (75%) following eight treatment cycles. However, 32% of the 2.4-mg/kg cohort achieved a complete response compared with 10% of the 1.8-mg/kg cohort. The complete response rate increased to 44% in the 2.4-mg/kg cohort following all cycles but remained at 10% in the 1.8-mg/kg cohort.

Researchers observed a median duration of response of 10 months in the 2.4 mg/kg arm. Median duration of response has not been reached in the 1.8 mg/kg cohort.

Researchers estimated a 61% 12-month PFS rate in the lower-dose cohort and a 66% 12-month PFS rate in the higher-dose cohort.

Similar rates of grade 3 or higher adverse events occurred in the high- and low-dose cohorts after eight cycles (52% vs. 50%). More patients assigned 2.4 mg/kg discontinued treatment due to an adverse event after eight cycles of treatment (28% vs. 25%) and after all cycles (56% vs. 30%).

One treatment-related patient death occurred due to pulmonary congestion in the 2.4-mg/kg cohort. The death occurred 2 months following the initiation of the twelfth treatment cycle.

“Tolerability may be improved by dosing polatuzumab vedotin at 1.8 mg/kg and a fixed duration of eight or fewer cycles,” Advani said. “Efficacy is seen at both dose levels, despite the higher number of complete remission at the higher dose. Polatuzumab may represent a clinical meaningful treatment option at the 1.8-mg/kg dose at the fixed duration of therapy, and studies of this combination of immunotherapy are ongoing in both large cell lymphoma and follicular lymphoma."by Cameron Kelsall


Advani RH, et al. Abstract 8503. Presented at: ASCO Annual Meeting; May 29-June 2, 2015; Chicago.

Disclosure: Advani reports honoraria, travel expense and research funding from Agensys, Allos Therapeutics, Celgene, Elsai, GE Healthcare Genentech/Roche, Idera, Janssen Pharmaceuticals, Millennium, Pharmacyclics and Seattle Genetics. Please see the abstract for a list of all other researchers’ relevant financial disclosures.