Inhibition of Hedgehog Signaling for the Treatment of Lymphoma and CLL: A Phase II Study from the Lysa

BACKGROUND

The Hedgehog (Hh) signaling pathway, which plays an important role during embryogenesis, can be reactivated in a wide range of cancers. Vismodegib, a selective hedgehog pathway inhibitor, demonstrated antitumor activity in medulloblastoma and basal-cell carcinoma (BCC) patients and has been approved by the FDA and EMA for the treatment of BCC. Preclinical data indicate that Hh pathway can also be activated in lymphoid malignancies and that its inhibition has antitumor activity (Dierks et al, Nature Med 2007; Singh et al, Leukemia 2012; Decker et al, Blood 2012).

METHODS

We conducted a phase II trial testing vismodegib in patients with relapsed/refractory lymphoma and CLL. Vismodegib was given orally at the dose of 150mg/day until disease progression or unacceptable toxicities for a maximum of one year. The primary objective was to evaluate the efficacy of vismodegib as measured by the best overall response rate (ORR) during the treatment period.

RESULTS

Between February 2013 and January 2014, 31 patients were recruited including diffuse large B-cell lymphoma (DLBCL, N=12), indolent lymphoma (iNHL, N=6), primary CNS lymphoma (PCNSL, N=10) and chronic lymphocytic leukemia (CLL, N=3). Patient characteristics are summarized in Table 1.

We found that Hh signaling pathway (measured by IHC and/or PCR based on the expression of SHH, PTCH 1 and 2, SMO, GLI 1, 2 and 3, and ABCG2) was frequently activated at baseline in lymphoma patients.

PK analysis demonstrated bioavailability of vismodegib in blood and CSF (median concentration at day 28 = 13398 [6970-20700] and 323 [99-717]ng/L, respectively).

Nevertheless, none of the patients responded to vismodegib therapy, except for one. This patient had an iNHL (grade 3a follicular lymphoma). He experienced a partial remission after 2 cycles that lasted for 4.8 months. Interestingly, this patient had the strongest expression of GLI (1, 2 and 3) by PCR compared to all the other patients tested.

All patients discontinued treatment prematurely (Table 1), mostly due to disease progression (90.3%).

Adverse events (AE) and serious AEs (SAE) related to vismodegib were observed in 51.6 and 12.9% of the patients, respectively. SAEs related to vismodegib were diarrhea, vomiting, lung infection, hypoglycemia, pulmonary embolism, and skin rash (1 patient each).

CONCLUSIONS

Despite frequent Hh pathway activation, treatment with vismodegib did not show significant clinical efficacy in patients with lymphoma or CLL.

This study was supported by Roche.