CVP chemo followed by Bexxar RIT produces impressive results in small study

The inaugural issue of the ASCO Post has been published, and its lead story concerns the long-term efficacy of radioimmunotherapy in patients with follicular lymphoma (FL). Specifically, this concerns the use of combination chemotherapy (CVP) followed by Bexxar.

COHORT

The multi-center study in question enrolled 30 US patients over age 18 who had been diagnosed with CD20-positive untreated stage III, IV, or bulky (tumor diameter ~ 5 em) stage II, low-grade FL.

DETAILS

Patients received six cycles of CVP chemotherapy on a 21 day cycle. (To remind our readers, CVP chemotherapy is similar to the more familiar CHOP therapy—the chief difference being that CVP excludes the anthracycline doxorubicin, making the combination safer for the patient's heart and lungs).

Tositumomab and l31I-tositumomab (Bexxar) were initiated within 56 days after day 1 of the sixth cycle of CVP.

All patients completed therapy according to plan.

Additionally, twenty-six patients received a 75-cGy dose of total-body radiation and the other four received a 65-cGy dose of total-body radiation.

RESULTS

Median follow-up: 8.4 years.

Response rates following the six cycles of CVP:
Complete response (CR) rate: 53%.
Partial response (PR) rate: 47%
Overall response (OOR) rate: 100%

After finishing the Bexxar phase, response rates were:
Complete response (CR) rate: 93%.
Overall response (ORR) rate: 100%

Additionally, six of the patients ultimately died of FL.

CONCLUSIONS

Said senior author John P Leonard, "These 8 year follow-up data show that CVP followed by radioimmunotherapy is a highly active first-line therapy for FL … [they] are the first description of sequentially combining 131-I radioimmunotherapy following CVP."

However, readers should take note of two competing aspects of this study: The first is the small number of patients. 30 patients is way too small to draw any significant and reliable conclusions about the efficacy of this therapy; what it really is good for is for encouraging continued research into it. On the other hand, the response rates are very encouraging, and they contribute to the growing body of peer-reviewed evidence that radioimmunotherapy is a safe, effective and viable means of fighting such a prevalent but notoriously hard-to-treat indolent cancer like FL.

Sources:
- The ASCO Post Volume 1, Issue 1, June 2010
- Link BK et al. "Cyclophosphamide, vincristine, and prednisone followed by tositumomab and iodine-131-tositumomab in patients with untreated low-grade follicular lymphoma: Eight-year follow-up of a multicenter phase II study." J Clin Oncol. May 10, 2010