Triplet disappoints in follicular lymphoma trial

Three patients were treated at DL0, 3 at DL1, and 16 at DL2. There were no DLTs reported at any dose level.

However, 11 patients required dose reductions due to toxicity (7 due to rash), and 12 patients ultimately discontinued treatment.

Reasons for discontinuation included progression (n=2), new diagnosis of carcinoma requiring systemic therapy (n=2), patient decision (n=3), and adverse events (n=6), including grade 3 rash (n=2), grade 3 atrial flutter (n=1), grade 3 diarrhea (n=1), hypertension (n=1), and depression (n=1). (One patient discontinued due to rash and progression.)

Adverse events

Dr Ujjani said the hematologic toxicity profile was similar to that observed with rituximab and lenalidomide in the front-line setting. Grade 3/4 hematologic toxicities included neutropenia (18.2%), thrombocytopenia (4.5%), anemia (4.5%), and lymphopenia (4.5%).

The most common non-hematologic toxicities (occurring in more than 20% of patients) were rash, diarrhea, fatigue, infusion-related reactions, nausea, infection, and neoplasms. There were no grade 4 non-hematologic toxicities.

Compared to rituximab and lenalidomide, the triplet was associated with an increase in rash, diarrhea, arthralgia, and neoplasm. There were 2 cutaneous neoplasms and 3 carcinomas.

Rash

“While no protocol-defined DLTs were observed, the regimen was associated with clinically significant rash,” Dr Ujjani noted. “Rash may have been related to individual study drugs or drug-drug interactions.”

Rash occurred in 82% of patients overall, 100% of patients treated at DL0, 67% at DL1, and 81% at DL2. The incidence of grade 1/2 rash was 46% overall, 67% at DL0, 33% at DL1, and 44% at DL2. The incidence of grade 3 rash was 36% overall, 33% at DL0 and DL1, and 38% at DL2.

The incidence of rash was similar whether or not patients received allopurinol. Ten of 11 patients on allopurinol had a rash, and 8 of 11 patients not on allopurinol had a rash.

“The time of [rash] onset was typically during cycle 1 but was seen as late as cycle 5,” Dr Ujjani said. “Grade 1 and 2 rashes resolved spontaneously without dose modification. The incidence of these milder rashes were comparable to our prior reports of rituximab and lenalidomide.”

“Grade 3 rash, however, occurred in 36% of patients, which is significantly higher than [with] rituximab and lenalidomide, [which is] typically 7% to 8%, or single-agent ibrutinib, which is about 3% to 4%.”

Patients with grade 3 rash were managed with supportive care, including acetaminophen, diphenhydramine, and oral corticosteroids.

All but 1 patient (7/8) had dose delays and reductions due to rash. One patient withdrew from the study because of rash, and 1 patient withdrew because of disease progression that occurred during a dose delay for rash.

Response and survival

The ORR was 95% for the entire cohort, 100% at DL0 and DL1 and 94% at DL2. The CR/unconfirmed CR rate was 63% overall, 67% at DL0, 33% at DL1, and 69% at DL2.

The partial response rate was 32% overall, 33% at DL0, 67% at DL1, and 25% at DL2. Five percent of patients had stable disease, all at DL2 (6% of this group).

The median time to first response was 2.3 months (range, 1.9 to 11.1). And the median time to best response was 5.5 months (range, 1.9 to 20.2).

At a median follow-up of 12.3 months, all patients are still alive. The 12-month PFS is 84%.

“Preliminary response data were similar to the prior CALGB/Alliance study of rituximab and lenalidomide,” Dr Ujjani noted. “However, given the increased toxicity and required dose modifications, the additional benefit of a third agent is not apparent, and further investigation of the triplet in this setting seems unwarranted.”