A Circulating T Cell Clone in Early Mycosis Fungoides Is Not a Negative Prognostic Factor When the Disease Is Treated by a Combination of PUVA + Interferon α.

In patients with early Mycosis Fungoides (MF), a dominant T-cell receptor (TCR) gene rearrangement can be detected in the skin in 50–75% of cases, while in 15–40%, an identical T-cell clone is detectable also in the peripheral blood This may indicate an unfavourable subset of patients.

We observed on omogeneus group of early MF patients all receiving the some protocol. The purpuose of this study were: - T-cell receptor gene rearrangement analisys of peropheral blood samples; - evaluation of the prognostic impact of T-cell monoclonality on CR and relapse rate.

44 patients diagnosed as having MF at early stage (25 M, 19 F; mean age 58.7 yrs, range 34–77; 11 in stage IA, 28 in stage IB, 5 in stage IIB) and showing a dominant T cell clone in the skin lesions at diagnosis, were included in the present study. Peripheral blood samples were collected for DNA extraction at diagnosis. PCR amplification for TCRγ gene was performed as previously reported by Ashton-Key et al. (1997) in all 44 cases both in peripheral blood and skin and reduplicated: amplification products were visualised by 10% polyacrylamide gel electrophoresis. Peripheral blood samples were considered positive for a circulating T cell clone only if the monoclonal signals in peripheral blood and skin were reproducible and overlapping.

All patients received the same treatment, consisting of a combination protocol with low-dose IFNα + PUVA for 14 months, and then followed up. Clinical response to the therapy and further disease recurrences were registered.

After a mean time of 6.02 months (range, 1–21), 7 patients failed to respond to combination therapy, while 37 obtained a clinical complete remission (CCR). Among them, 15 experienced a disease recurrence during the follow-up (mean time, 29.8 months, range, 1–77 months).

PCR analysis of TCRγ gene showed in the peripheral blood the same T-cell clone detected in the skin in 16 cases (36.4%). Failure to obtain a CCR was found in 3 out of 28 cases without a T cell clone in peripheral blood (10.7%) and in 4 out 16 cases with a circulating T cell clone (25%; c2 test: P=0.41, NS). Disease recurrence was observed in 9 out of 25 cases without a T cell clone in peripheral blood (36%) and in 6 out of 12 cases with a circulating T cell clone (50%; c2 test: P=0.65, NS). Disease-free survival curves plotted by Kaplan-Meier method showed that patients with and without a circulating T cell clone did not behave differently and that half of the patients would have experienced a relapse after a similar period of time (34 and 36 months, respectively, for patients with TCRg+ and − peripheral blood; log rank test, P=0.79).

PCR analysis of TCRγ gene rearrangement analysis has allowed us to detect monoclonality in the peripheral blood in 36% of early MF cases with a documented monoclonality in the skin. At this stage of the disease a circulating T cell clone could indicate a subset of patients in which skin-directed therapies are more likely to fail to completely eradicate the malignant cells. Interestingly, our data seems to show that the negative influence of a circulating clone can be bypassed by the combination of a skin-directed therapy like PUVA and the systemic immunoregulatory effects of IFNα.