Table 1.
Baseline Characteristics
| RET-mutant MTC | RET Fusion-Positive Thyroid Cancer | ||
|---|---|---|---|
| Characteristic | Vandetanib and/or Cabozantinib pre-treated | Vandetanib/Cabozantinib Naïve | |
| (N=55) | (N=88) | (N=19) | |
| Age, Median (range) – yr | 57 (17–84) | 58 (15–82) | 54 (25–88) |
| Sex – no. (%) | |||
| Male | 36 (66) | 58 (66) | 9 (47) |
| Female | 19 (35) | 30 (34) | 10 (53) |
| Race – no. (%) * | |||
| White | 49 (89) | 75 (85) | 14 (74) |
| Asian | 0 | 4 (5) | 2 (11) |
| Black or African American | 1 (2) | 1 (1) | 1 (5) |
| Other | 5 (9) | 8 (9) | 2 (11) |
| ECOG performance status – no. (%) | |||
| 0 | 11 (20) | 43 (49) | 5 (26) |
| 1 | 41 (75) | 42 (48) | 12 (63) |
| 2 | 3 (6) | 3 (3) | 2 (11) |
| Thyroid cancer tumor type | |||
| Medullary | 55 (100) | 88 (100) | |
| Papillary | 13 (68) | ||
| Poorly differentiated | 3 (16) | ||
| Hürthle cell | 1 (5) | ||
| Anaplastic | 2 (11) | ||
| Median prior systemic regimens (range) – no. | 2 (1–8) | 0 (0–2) | 4 (1–7) |
| Prior cabozantinib and/or vandetanib | 55 (100) | 0 | |
| Vandetanib only | 18 (33) | 0 | |
| Cabozantinib only | 13 (24) | 0 | |
| Cabozantinib and vandetanib | 24 (44) | 0 | |
| Prior radioactive iodine (RAI) | 16 (84) | ||
| Prior sorafenib and/or lenvatinib | 13 (68) | ||
| Prior multikinase inhibitor therapy – no. (%) | 55 (100) | 7 (8) | 15 (79) |
| 1 | 26 (47) | 6 (7) | 7 (37) |
| ≥2 | 29 (53) | 1 (1) | 8 (42) |
| Prior non-multikinase inhibitor therapy– no. (%) | 17 (31) | 9 (10) | 14 (74) |
| Brain metastases – no. (%) | 4 (7) | 2 (2) | 6 (32) |
| RET alteration – no. (%) | |||
| RET M918T mutation | 33 (60) | 49 (56) | - |
| RET V804M/L mutation | 5 (9) | 6 (7) | - |
| RET extracellular cysteine mutation** | 7 (13) | 20 (23) | - |
| Other mutations† | 10 (18) | 13 (15) | - |
| CCDC6-RET fusion | - | - | 9 (47) |
| NCOA4-RET fusion | - | - | 6 (32) |
| Other RET fusion‡ | - | - | 4 (21) |
*
Includes 1 RET fusion-positive patient with missing race
**
Extracellular cysteine mutation defined as mutation including at least 1 of the following cysteine residues: 609, 611, 618, 620, 630, and 634.
†
Other includes: D631-L633delinsE, E632-L633del, A883F, D631-L633delinsV, L790F, D898-E901del, D898_E901del + D903_S904delinsEP, K666N, T636-V637insCRT, D378-G385delinsE.
‡
Fusions identified in single tumors included CCDC186-RET, ERC1-RET, KTN1-RET, and RUFY3-RET.
Eastern Cooperative Oncology Group (ECOG) performance status scores range from 0 to 5, with higher scores indicating greater disability. Total % may be different than the sum of the individual components due to rounding.