TUMOR-TARGETED SUPERANTIGENS - Fusion Protein Technologies for Biopharmaceuticals: Applications and Challenges - page 365

10 m g/kg/day, three patients received 16.5 m g/kg/day, and
seven patients got 22 m g/kg/day of naptumomab estafenatox.
No synergistic toxicities were observed. Best overall responses
at 2 or 4 months were two patients with partial remissions (PR),
five with SD, and three with progressive disease (Figure 24.6)
while three patients were not evaluable. Notably, 11/13
patients had stage IV NSCLC. Biopsies were taken from
two patients at day 3 of the second cycle. Both patients showed
confirmation of tumor 5T4 expression and increased T-cell
infiltration in association to the metastases (Figure 24.6). One
of these patients had PR (Figure 24.6). The median survival for
the patients was 9.3 months. Antibody formation against
SEA/E-120 was low in these patients. The hypothesis included
reduced increase of anti-SAg (anti-SEA/E-120) antibodies by
the combination of TTS with docetaxel. We compared anti-
SEA/E-120 levels after the first treatment cycle in the
COMBO study with the MONO study and showed that
docetaxel reduced anti-SAg antibody production when it
was given one day after the last injection in a treatment
cycle with naptumomab estafenatox (Figure 24.6). Since
the avoidance of high titer neutralizing antibodies would be
advantageous for multicycle treatment with naptumomab
estafenatox, combinations with docetaxel or other inhibi-
tors of anti-SAg antibody production would probably
be beneficial. In addition, docetaxel interferes with
immune suppression resulting in enhanced or sustained
CTL activity [62], a feature also considered to be important
for an optimal antitumor effect with naptumomab estafe-
natox treatment.
Promising clinical results were accomplished using nap-
tumomab estafenatox and its predecessor in Phases I and IIa
monotherapy studies with RCC patients. In preclinical
models, IFN- a was shown to enhance and sustain TTS
induced CTL activity when given in combination [21]. In
early 2007, patient recruitment started in a pivotal add-on to
IFN- a combination trial with naptumomab estafenatox in
advanced RCC. This trial is conducted as a multicenter
(involving

parallel-group, Phase II/III trial in patients with confirmed
metastatic or inoperable locally advanced RCC eligible for
standard therapy with IFN- a . Recruitment was completed in
May 2009 with 527 patients randomized for treatment with
IFN- a with or without naptumomab estafenatox. OS (pri-
mary endpoint) results are anticipated in due time.

24.6 COMBINING TTS WITH CYTOSTATIC AND
IMMUNOMODULATING ANTICANCER DRUGS

Many established cancer treatments utilize multiple mecha-
nisms of action to add therapeutic effect by combining two
or more compounds. Therefore, establishment of combina-
tions with other antitumor treatments was integrated within
the development of the TTS fusion proteins. Apart from
gaining therapeutic effect by combining with other antitu-
mor mechanisms, we also searched for combination sched-
ules interfering with anti-SAg antibody production and
hindrance of tumor-induced immune suppression or anergy.
In addition, combination with certain anticancer drugs with
distinct mechanisms of action would potentially result in not
only additive but even synergistic tumor disease inhibition.
We have elaborated a series of combinations between
TTS fusion proteins and other anticancer or immune mod-
ulating drugs: the cytostatic drugs docetaxel [63] and gem-
citabine [64]; the anti-angiogenic drugs sunitinib [65] and
bevacizumab [66]; the cytokines IL-2 [67,68] and IFN- a
[67,68]; and the immune modulatory mAbs anti-CD25 [69],
anti-CTLA-4 [67,70], and anti-Gr-1 [71].
Preclinical studies of C215Fab-SEA in the B16-EpCAM
model showed enhanced antitumor effects when used in
combination with docetaxel (Figure 24.7) [22] and gemci-
tabine (Table 24.3). It can be anticipated that the additive or
in certain settings synergistic antitumor effects recorded
with these combinations were results of the distinct mecha-
nisms of action when combining cytostatics with immuno-
therapy. It should be emphasized though, that inhibition of
immune suppression by docetaxel and gemcitabine has been

50 sites in Bulgaria, Romania, Russia, the
United Kingdom, and Ukraine), randomized, open-label,

J

FIGURE 24.7 Survival of syngeneic mice with B16-EpCAM lung tumors treated with C215Fab-
SEA i.v. (A-C), (A) IFN- a i.p., Source: Reproduced from Reference 21, with permission from
Elsevier. (B) anti-CTLA-4 mAb i.p., Source: Reproduced from Reference 74, with permission from
Wolters Kluwer Health. (C) docetaxel i.p., Source: Reprinted fromReference 22, with permission from
Elsevier, or the combinations and tumor growth in SCID mice with human tumors growing i.p. treated
according to (D-F). (D) SCID mice with human renal cell carcinoma Caki-2 growing i.p. were treated
with one or two cycles of activated human T lymphocytes (i.p.) day 5 or days 5 and 26 and 50 m gof
naptumomab estafenatox (nap) (i.v.) days 5-8 or 5-8 and 26-29 or were treatedwith 200 m g of sunitinib
(sun) (p.o.) days 1-25 and days 30-54, one cycle of activated human T lymphocytes (i.p.) day 26 and
5 m g of nap (i.v.) days 26-29, or the combination. (E) SCID mice with the human colon carcinoma
Colo205 growing i.p. were treatedwith a series of 100 m g bevacizumab (bev) (i.p.) injections, one cycle
of activated human T lymphocytes (i.p.) day 5 and 50 m g of nap (i.v.) days 5-8, or the combination.
(F) SCIDmicewith the humanNSCLCCalu-1 growing i.p. were treatedwith 200 m g of docetaxel (doc)
(i.p.) at day 7, one cycle of activated human T lymphocytes (i.p.) day 2 and 50 m g of nap (i.v.) days 2-6,
or the combination.