Table 4.
Redifferentiation and 131I Efficacy Outcomes Achieved for All Patients (N = 7)
| Patient no. | Thyroid pathology | Metastatic disease sitesa | Lifetime 131I received before study, mCi (no. doses given) | Baseline 124I avidity (avid organ site) | Increased 124I avidity with V+C/lesional dosimetry threshold for 131I met? | 131I given/MTA, mCi (% of MTA given) | Tumor size change with V + C alone relative to baseline, % | Tumor size change 3 months post-tx with 131I relative to baseline, % | Tumor size change 6 months post-tx with 131I relative to baseline, % | Best overall response at 6 months |
|---|---|---|---|---|---|---|---|---|---|---|
| 131I treated | ||||||||||
| 1 | PDTC | L, TB, ML | 29 (1) | + (ML, TB) | Yes/Yes | 284/293 (97) | −21% | −42% | −42% | PR |
| 2 | PTC (TCV) | TB, L, NL | 200 (1) | None | Yes/Yes | 197/588 (34) | −13% | −10% | — | PD |
| 4 | PTC | TB, NL, PT, L | 125 (1) | None | Yes/Yes | 299/571 (52) | −10% | −30% | −50% | PR |
| 5 | PDTC | TB, PT, HL, ML, OL. STb | 0 | + (PT, TB) | Yesb/Yes | 201/668 (30) | — | 6%b | — | PDb |
| No131I given | ||||||||||
| 3 | PTC | L, TB | 242 (1) | + (TB, L) | Yesc/No | — | −8%d | Brain metastasis detected/treated almost 3 years after study treatment | ||
| 6 | PTC (TCV) | TB, NL, ML, L | 175 (1) | None | — | — | 5%e | Did not receive CDX-3379, treated with vem only on study; initiated systemic therapy ∼3 years after vem | ||
| 7 | PDTC | TB, NL, L, B, ST | 102 (1) | + (TB, L) | No/No | — | −31%f | Initiated systemic therapy immediately after coming off study | ||
Italicized metastatic disease site indicates metastatic sites identified by 124I PET/CT only.
Heterogeneous response with increased 124I was noted in the thyroid bed and paratracheal disease, but not in the hilar, mediastinal, and obturator lymph nodes or the soft tissue deposit. Tumor growth after three months of 131I was noted at sites lacking 131I avidity, resulting in a RECIST designation of PD.
New, increased 124I uptake with study therapy that met lesional dosimetry criteria for 131I therapy but was not treated because a structural correlate for the former could not be identified on imaging.
Imaging performed ∼7 months after last dose of study drugs.
Imaging performed ∼7 months after last dose of vemurafenib; did not receive CDX-3379.
Comparison of neck disease was carried out between MRI at baseline and CT performed within ∼1 month of drug therapy. Lung nodules that were measured were compared between CT scans.
I PET-CT, iodine-124 positron emission tomography–computed tomography; B, bone; HL, hilar lymph node; L, lung; ML, mediastinal lymph node; MTA, maximum tolerable activity (calculated by blood dosimetry); NL, neck lymph node; OL, obturator lymph node; PD, progression of disease; PDTC, poorly differentiated thyroid carcinoma; PR, partial response; PT, paratracheal disease; PTC, papillary thyroid carcinoma; post-tx, post-treatment; ST, soft tissue deposit; TB, thyroid bed; TCV, tall cell variant; V+C, vemurafenib plus CDX-3379.