Clinical activity and safety of combination therapy with temsirolimus and bevacizumab for advanced melanoma: a phase II trial (CTEP 7190/Mel47)

Abstract

Purpose: A CTEP-sponsored phase II trial was conducted to evaluate safety and clinical activity of combination therapy with CCI-779 (temsirolimus) and bevacizumab in patients with advanced melanoma.

Experimental design: Patients with unresectable stage III to IV melanoma were treated intravenously with temsirolimus 25 mg weekly and bevacizumab 10 mg every 2 weeks. Adverse events were recorded using CTCAE v3.0. Tumor response was assessed by Response Evaluation Criteria in Solid Tumors and overall survival was recorded. Correlative studies measured protein kinases and histology of tumor biopsies and immune function in peripheral blood.

Results: Seventeen patients were treated. Most patients tolerated treatment well, but 2 had grade 4 lymphopenia and 1 developed reversible grade 2 leukoencephalopathy. Best clinical response was partial response (PR) in 3 patients [17.7%, 90% confidence interval (CI) 5, 0-39.6], stable disease at 8 weeks (SD) in 9 patients, progressive disease (PD) in 4 patients, and not evaluable in 1 patient. Maximal response duration for PR was 35 months. Ten evaluable patients had BRAF(WT) tumors, among whom 3 had PRs, 5 had SD, and 2 had PD. Correlative studies of tumor biopsies revealed decreased phospho-S6K (d2 and d23 vs. d1, P < 0.001), and decreased mitotic rate (Ki67(+)) among melanoma cells by d23 (P = 0.007). Effects on immune functions were mixed, with decreased alloreactive T-cell responses and decreased circulating CD4(+)FoxP3(+) cells.

Conclusion: These data provide preliminary evidence for clinical activity of combination therapy with temsirolimus and bevacizumab, which may be greater in patients with BRAF(wt) melanoma. Mixed effects on immunologic function also support combination with immune therapies.

Figure 1. Clinical trial schematic

Drug treatment (top row) and tissue and blood collection (bottom row) are indicated. DLT, dose-limiting toxicity.

Figure 2. Waterfall plots of best overall response (BOR) after treatment

Percent change in tumor diameters by RECIST criteria. (A) All 16 evaluable patients; patients with BRAF^WT tumors are in blue and those with BRAF^V600E tumors are in red. RR, response rate. DCR, disease control rate; (B) BRAF^WT patients only; C) Kaplan-Meier estimates for overall survival of patients by BRAF status (blue dotted line, WT; red solid line, V600E); (D) Percent reduction in tumor diameters (RECIST) over time, compared to pre-treatment measurements, for the 3 patients with PR. Patient 7 came off treatment after cycle 4 due to toxicity, with progression at 35 months. Patient 10 had 30% decrease in tumor diameters at cycle 8 (17.5 weeks), 29% decrease at confirmation 8 weeks later, and subsequent lack of progression for 9 months. Patient 16 came off study due to a new lesion (*) at cycle 12. One cycle = 2 weeks.

Figure 3. Durable partial response, Patient 7

Extensive cutaneous melanoma metastases in the right groin are shown pretreatment (A) and after 17 months (B) for the patient with the best response to therapy. Sites of disease that were biopsied for the study are shown with dotted lines in (A), and the scars are evident in (B). CT scan images are shown for inguinal, iliac, and periaortic adenopathy pretreatment (C) and after 21–30 months (D). Sites of disease are marked with red circles.

Figure 4. Changes in phosphoproteins and Ki67 expression by melanoma cells in metastases with treatment

(A) Normalized protein expression of phosphorylated S6K (P-Ser235/236 and P-Ser240/244) in tumor samples detected by Reverse phase protein array (RPPA), before treatment (D1), after 24h temsirolimus alone (D2), and after combination treatment (D23). Values are shown for all patients with tissue available for analysis. Protein expression was normalized for protein loading and transformed to linear values. (B) Western blot of total S6K protein (Total S6) and phosphorylated S6 [P-Ser235/236] from tumor biopsies obtained pre-treatment (D1), 24h post-temsirolimus alone (D2), and post-combination treatment, day 23 (D23). Samples from 3 patients (Patient 1, 8, and 7) are shown. Patient 7 did not have tumor biopsy on day 23. GAPDH is blotted as a loading control. (C) Ki67+ melanoma cells were enumerated in tumor biopsies by immunohistochemistry, and values per high powered field (HPF) are shown for BRAF^WT and BRAF^V600E melanomas. Wide black lines are two patients with PRs. Dashed lines are in patients with PD.

Figure 5. Immunologic correlates of treatment with temsiroliumus plus bevacizumab

PBMC were obtained Day 1 (0h), prior to the administration of study drug(s) and at each of the following: Day 1 (6, 12, 24h), and for Day 22 (0, 6–12, 24h); D1 + 24h = D2; D22 + 24h = D23. Interferon gamma (IFNγ) secreting cells were enumerated by ELIspot assay after mitogen-induction (PMA/ionomycin, A) or viral recall antigen stimulation (CEF peptide pool, B). Graphs of both individual patients and mean/medians are shown. C) proliferation after alloantigen exposure (mixed lymphocyte reaction) was determined after 5 days (n=11), D) Circulating regulatory T cells were estimated by determining the proportion of CD4+ cells that were CD25^hi FoxP3⁺ and CD127^lo at each time point (n=7). For (C) and (D), data are presented with box plots showing median values (dot), 25^th and 75^th percentiles (box), maximum and minimum values (whiskers); * p < 0.02; ** p<0.001.