Community-Based Trial of R-CHOP and Maintenance Rituximab for Intermediate- or High-Grade Non-Hodgkin Lymphoma with First-Cycle Filgrastim for Older Patients

BACKGROUND

Administration of full-dose R-CHOP (rituximab/cyclophosphamide/doxorubicin/vincristine/prednisone) chemotherapy is important to maximize response in patients with intermediate-or high-grade non-Hodgkin lymphoma but might be difficult in older patients.

PATIENTS AND METHODS

This community-based study was conducted to determine response, toxicity, and disease-free survival in patients with intermediate-or high-grade non-Hodgkin lymphoma receiving R-CHOP with filgrastim. Patients received 6-8 cycles of R-CHOP followed by 4 cycles of maintenance rituximab for responders. Patients aged > 60 years or with increased infection risk received filgrastim 5 microg/kg per day in all R-CHOP cycles; other patients received filgrastim after a neutropenic event (no planned administration for cycle 1).

RESULTS

Of 101 patients enrolled, 60 (59%) were aged > 60 years and received filgrastim in all cycles. Thirty-three patients aged <or= 60 years (80%) received filgrastim, 7 (17%) as primary use in cycle 1. Chemotherapy average relative dose intensity was comparable between age groups (91% > 60 years vs. 93% <or= 60 years). Overall response was similar in both groups (87% > 60 years vs. 95% <or= 60 years; P=0.19); however, the complete response rate was significantly lower for older patients (42% > 60 years vs. 71% <or= 60 years; P=0.005). Seventy-six percent of patients (75% > 60 years vs. 78% <or= 60 years) had no evidence of progression after 2 years of follow-up. Febrile neutropenia (fever >or= 38.3 degrees C with absolute neutrophil count < 500/mm) occurred in 17% of patients overall (22% > 60 years vs. 10% <or= 60 years), and 8% had cycle-1 events (12% > 60 years vs. 2% <or= 60 years).

CONCLUSION

Patients aged > 60 years receiving R-CHOP with filgrastim support in all cycles received comparable doses of chemotherapy and had similar overall response rates compared wtih those of younger patients receiving no preemptive cycle-1 filgrastim.

Dual effects of a phorbol ester on calcium-dependent chloride secretion by T84 epithelial cells

Ca(2+)-dependent secretagogues (e.g., carbachol, histamine, ionomycin, and 4-bromo-A23187) have relatively transient effects on chloride secretion, even if there is a sustained increase in cytosolic calcium ([Ca2+]i) (as for the ionophores). Because these agents increase both [Ca2+]i and protein kinase C (PKC) activity, chloride secretion might be stimulated by [Ca2+]i and terminated by PKC activity. We tested the effect of a PKC activator, phorbol 12-myristate 13-acetate (PMA), on Cl- secretion by T84 cell monolayers by measuring short-circuit current (Isc). PMA alone had no effect on Isc but potentiated increases in Isc when added 10 min or less before Ca(2+)-dependent secretagogues. Chelation of [Ca2+]i with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid inhibited the increases both in [Ca2+]i and Isc induced by carbachol with or without brief PMA pretreatment. Longer preincubations with PMA inhibited Isc responses to Ca(2+)-dependent secretagogues, even when increased [Ca2+]i was sustained by ionophores. Inhibitors of PKC could reverse the inhibitory effect of PMA but did not reverse the potentiating effect. The effects of PMA on Cl- secretion were reproduced by 1,2-dioctanoyl-sn-glycerol and were mirrored by effects on K+ channel opening. Thus PMA has dual effects on chloride secretion. Initially, it exerts a stimulatory action and subsequently an inhibitory action. The stimulatory effect only occurs if Ca(2+)-dependent secretion is ongoing. The inhibitory effect of PMA is mediated by PKC and cannot be overcome by increasing [Ca2+]i.

Cl- secretion induced by bile salts. A study of the mechanism of action based on a cultured colonic epithelial cell line

When applied to the basolateral (serosal) side of the T84 colonic epithelial monolayer, taurodeoxycholate caused net Cl- secretion in a dose-dependent manner with a threshold effect observed at 0.2 mM. In contrast, when applied to the apical (luminal) surface, concentrations of taurodeoxycholate below 1 mM had little or no effect. Only when the concentration of taurodeoxycholate present on the apical side was greater than or equal to 1 mM did apical addition results in an electrolyte transport effect. This apical effect on electrolyte transport was associated with an abrupt increase in the permeability of the monolayer. Cyclic AMP and cyclic GMP in the T84 monolayers were not increased by the bile salt, but in the presence of extracellular Ca2+, free cytosolic Ca2+ increased with a graded dose effect and time course that corresponded approximately to the changes in short circuit current (Isc). The results suggest that luminal bile salts at a relatively high concentration (greater than or equal to 1 mM) increase tight junction permeability. Once tight junction permeability increases, luminal bile salts could reach the basolateral membrane of the epithelial cells where they act to increase free cytosolic Ca2+ from extracellular sources. The resulting increases in free cytosolic Ca2+, rather than in cyclic nucleotides, appear to be involved in transcellular Cl- secretion.